Alien-FreeImage
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src/Source/LibOpenJPEG/tgt.h
src/Source/LibOpenJPEG/THANKS
src/Source/LibOpenJPEG/thix_manager.c
src/Source/LibOpenJPEG/tpix_manager.c
src/Source/LibPNG/ANNOUNCE
src/Source/LibPNG/CHANGES
src/Source/LibPNG/CMakeLists.txt
src/Source/LibPNG/configure
src/Source/LibPNG/example.c
src/Source/LibPNG/INSTALL
src/Source/LibPNG/libpng-manual.txt
src/Source/LibPNG/LibPNG.2005.vcproj
src/Source/LibPNG/LibPNG.2008.vcproj
src/Source/LibPNG/LibPNG.2013.vcxproj
src/Source/LibPNG/LibPNG.2013.vcxproj.filters
src/Source/LibPNG/libpng.3
src/Source/LibPNG/libpngpf.3
src/Source/LibPNG/LICENSE
src/Source/LibPNG/png.5
src/Source/LibPNG/png.c
src/Source/LibPNG/png.h
src/Source/LibPNG/pngconf.h
src/Source/LibPNG/pngdebug.h
src/Source/LibPNG/pngerror.c
src/Source/LibPNG/pngget.c
src/Source/LibPNG/pnginfo.h
src/Source/LibPNG/pnglibconf.h
src/Source/LibPNG/pngmem.c
src/Source/LibPNG/pngpread.c
src/Source/LibPNG/pngpriv.h
src/Source/LibPNG/pngread.c
src/Source/LibPNG/pngrio.c
src/Source/LibPNG/pngrtran.c
src/Source/LibPNG/pngrutil.c
src/Source/LibPNG/pngset.c
src/Source/LibPNG/pngstruct.h
src/Source/LibPNG/pngtest.c
src/Source/LibPNG/pngtrans.c
src/Source/LibPNG/pngwio.c
src/Source/LibPNG/pngwrite.c
src/Source/LibPNG/pngwtran.c
src/Source/LibPNG/pngwutil.c
src/Source/LibPNG/README
src/Source/LibPNG/TODO
src/Source/LibRawLite/Changelog.txt
src/Source/LibRawLite/COPYRIGHT
src/Source/LibRawLite/dcraw/dcraw.1.html
src/Source/LibRawLite/dcraw/dcraw.c
src/Source/LibRawLite/DEVELOPER-NOTES
src/Source/LibRawLite/internal/aahd_demosaic.cpp
src/Source/LibRawLite/internal/dcb_demosaicing.c
src/Source/LibRawLite/internal/dcraw_common.cpp
src/Makefile.srcs view on Meta::CPAN
VER_MAJOR = 3
VER_MINOR = 17.0
SRCS = ./Source/FreeImage/BitmapAccess.cpp ./Source/FreeImage/ColorLookup.cpp ./Source/FreeImage/FreeImage.cpp ./Source/FreeImage/FreeImageC.c ./Source/FreeImage/FreeImageIO.cpp ./Source/FreeImage/GetType.cpp ./Source/FreeImage/MemoryIO.cpp ./Source/...
INCLS = ./Examples/OpenGL/TextureManager/TextureManager.h ./Examples/Plugin/PluginCradle.h ./Examples/Generic/FIIO_Mem.h ./Source/MapIntrospector.h ./Source/FreeImage - Copie.h ./Source/CacheFile.h ./Source/LibTIFF/tiffconf.vc.h ./Source/LibTIFF/tif_...
INCLUDE = -I. -ISource -ISource/Metadata -ISource/FreeImageToolkit -ISource/LibJPEG -ISource/LibPNG -ISource/LibTIFF4 -ISource/ZLib -ISource/LibOpenJPEG -ISource/OpenEXR -ISource/OpenEXR/Half -ISource/OpenEXR/Iex -ISource/OpenEXR/IlmImf -ISource/Open...
src/README.linux view on Meta::CPAN
Release Notes
--------------
This version of the library has been tested under the following OS:
- RedHat Linux 7.3, 8.0 and 9.0
- Fedora Core 2
- SuSE Linux Enterprise 8 and SuSE 9.0.
- Debian 4
You *do not* need to have any other third party library (libjpeg, libpng, libtiff, libmng and zlib)
installed on your /usr/lib directory in order to compile and use the library.
FreeImage uses its own versions of these libraries. This way, you can be sure that FreeImage will
always use the latest version of each third party library.
The FreeImage makefile makes use of the gcc "-fvisibility=hidden" in order to avoid incompatibilities between
internal third party libraries and the OS libraries. You may have to remove this option if you're running an
old version of gcc. See also http://gcc.gnu.org/wiki/Visibility
You should be able to link progams with the -lfreeimage option after the library is compiled and installed.
You can also statically link with libfreeimage.a.
src/README.minGW view on Meta::CPAN
C:\>gcc -oFreeImageTest.exe FreeImageTest.c -lfreeimage
---------------------------------------------------------------------
2. Building the FreeImage library with MinGW
=====================================================================
You *do not* need to have any other third party library (like
libjpeg, libpng, libtiff, libmng and zlib and others) installed on
your system in order to compile and use the library. FreeImage uses
its own versions of these libraries. This way, you can be sure that
FreeImage will always use the latest and properly tested versions
of of these third party libraries.
In order to build the FreeImage library under Windows with MinGW
(GCC), ensure that all the prerequisites mentioned above are met.
The MinGW makefile aims to build a Windows DLL, that differs as
least as possible from the precompiled library that comes with the
FreeImage distribution. Thus, the build process also includes the
src/Source/FreeImage/MNGHelper.cpp view on Meta::CPAN
// THIS DISCLAIMER.
//
// Use at your own risk!
// ==========================================================
#include "FreeImage.h"
#include "Utilities.h"
/**
References
http://www.libpng.org/pub/mng/spec/jng.html
http://www.w3.org/TR/PNG/
http://libpng.org/pub/mng/spec/
*/
// --------------------------------------------------------------------------
#define MNG_INCLUDE_JNG
#ifdef MNG_INCLUDE_JNG
#define MNG_COLORTYPE_JPEGGRAY 8 /* JHDR */
#define MNG_COLORTYPE_JPEGCOLOR 10
#define MNG_COLORTYPE_JPEGGRAYA 12
src/Source/FreeImage/MNGHelper.cpp view on Meta::CPAN
#endif /* MNG_INCLUDE_JNG */
// --------------------------------------------------------------------------
#define JNG_SUPPORTED
/** Size of a JDAT chunk on writing */
const DWORD JPEG_CHUNK_SIZE = 8192;
/** PNG signature */
static const BYTE g_png_signature[8] = { 137, 80, 78, 71, 13, 10, 26, 10 };
/** JNG signature */
static const BYTE g_jng_signature[8] = { 139, 74, 78, 71, 13, 10, 26, 10 };
// --------------------------------------------------------------------------
/** Chunk type converted to enum */
enum eChunckType {
UNKNOWN_CHUNCK,
MHDR,
BACK,
src/Source/FreeImage/MNGHelper.cpp view on Meta::CPAN
// - crc
crc_file = FreeImage_ZLibCRC32(0, chunk_name, 4);
mng_SwapLong(&crc_file);
FreeImage_WriteMemory(&crc_file, 1, 4, hPngMemory);
}
}
/**
Wrap a IDAT chunk as a PNG stream.
The stream has the structure { g_png_signature, IHDR, IDAT, IEND }
The image is assumed to be a greyscale image.
@param jng_width Image width
@param jng_height Image height
@param jng_alpha_sample_depth Bits per pixel
@param mChunk PNG grayscale IDAT format
@param mLength IDAT chunk length
@param hPngMemory Output memory stream
*/
static void
mng_WritePNGStream(DWORD jng_width, DWORD jng_height, BYTE jng_alpha_sample_depth, BYTE *mChunk, DWORD mLength, FIMEMORY *hPngMemory) {
// PNG grayscale IDAT format
BYTE data[14];
// wrap the IDAT chunk as a PNG stream
// write PNG file signature
FreeImage_WriteMemory(g_png_signature, 1, 8, hPngMemory);
// write a IHDR chunk ...
/*
The IHDR chunk must appear FIRST. It contains:
Width: 4 bytes
Height: 4 bytes
Bit depth: 1 byte
Color type: 1 byte
Compression method: 1 byte
Filter method: 1 byte
src/Source/FreeImage/MNGHelper.cpp view on Meta::CPAN
// wrap the { IHDR, ..., IEND } chunks as a PNG stream
if(hPngMemory == NULL) {
hPngMemory = FreeImage_OpenMemory();
}
mOrigPos = io->tell_proc(handle);
// write PNG file signature
FreeImage_SeekMemory(hPngMemory, 0, SEEK_SET);
FreeImage_WriteMemory(g_png_signature, 1, 8, hPngMemory);
mChunk = (BYTE*)realloc(mChunk, m_TotalBytesOfChunks);
if(!mChunk) {
FreeImage_OutputMessageProc(format_id, "Error while parsing %s chunk: out of memory", mChunkName);
throw (const char*)NULL;
}
// on calling CountPNGChunks earlier, we were in Offset pos,
// go back there
io->seek_proc(handle, Offset, SEEK_SET);
src/Source/FreeImage/MNGHelper.cpp view on Meta::CPAN
BOOL bResult = FALSE;
DWORD start_pos = 0;
DWORD next_pos = 0;
long offset = 8;
do {
// find the next IDAT chunk from 'offset' position
bResult = mng_FindChunk(hPngMemory, mng_IDAT, offset, &start_pos, &next_pos);
if(!bResult) break;
BYTE *png_data = NULL;
DWORD size_in_bytes = 0;
// get a pointer to the stream buffer
FreeImage_AcquireMemory(hPngMemory, &png_data, &size_in_bytes);
// write the IDAT chunk
mng_WriteChunk(mng_IDAT, &png_data[start_pos+8], next_pos - start_pos - 12, hJngMemory);
offset = next_pos;
} while(bResult);
}
FreeImage_CloseMemory(hPngMemory);
hPngMemory = NULL;
}
src/Source/FreeImage/PluginICO.cpp view on Meta::CPAN
return dwSize;
}
/**
Vista icon support
@return Returns TRUE if the bitmap data is stored in PNG format
*/
static BOOL
IsPNG(FreeImageIO *io, fi_handle handle) {
BYTE png_signature[8] = { 137, 80, 78, 71, 13, 10, 26, 10 };
BYTE signature[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
long tell = io->tell_proc(handle);
io->read_proc(&signature, 1, 8, handle);
BOOL bIsPNG = (memcmp(png_signature, signature, 8) == 0);
io->seek_proc(handle, tell, SEEK_SET);
return bIsPNG;
}
#ifdef FREEIMAGE_BIGENDIAN
static void
SwapInfoHeader(BITMAPINFOHEADER *header) {
SwapLong(&header->biSize);
SwapLong((DWORD *)&header->biWidth);
src/Source/FreeImage/PluginPNG.cpp view on Meta::CPAN
#include "FreeImage.h"
#include "Utilities.h"
#include "../Metadata/FreeImageTag.h"
// ----------------------------------------------------------
#define PNG_BYTES_TO_CHECK 8
#undef PNG_Z_DEFAULT_COMPRESSION // already used in ../LibPNG/pnglibconf.h
// ----------------------------------------------------------
#include "../ZLib/zlib.h"
#include "../LibPNG/png.h"
// ----------------------------------------------------------
typedef struct {
FreeImageIO *s_io;
fi_handle s_handle;
} fi_ioStructure, *pfi_ioStructure;
// ==========================================================
// libpng interface
// ==========================================================
static void
_ReadProc(png_structp png_ptr, unsigned char *data, png_size_t size) {
pfi_ioStructure pfio = (pfi_ioStructure)png_get_io_ptr(png_ptr);
unsigned n = pfio->s_io->read_proc(data, (unsigned int)size, 1, pfio->s_handle);
if(size && (n == 0)) {
throw "Read error: invalid or corrupted PNG file";
}
}
static void
_WriteProc(png_structp png_ptr, unsigned char *data, png_size_t size) {
pfi_ioStructure pfio = (pfi_ioStructure)png_get_io_ptr(png_ptr);
pfio->s_io->write_proc(data, (unsigned int)size, 1, pfio->s_handle);
}
static void
_FlushProc(png_structp png_ptr) {
(png_structp)png_ptr;
// empty flush implementation
}
static void
error_handler(png_structp png_ptr, const char *error) {
(png_structp)png_ptr;
throw error;
}
// in FreeImage warnings disabled
static void
warning_handler(png_structp png_ptr, const char *warning) {
(png_structp)png_ptr;
(char*)warning;
}
// ==========================================================
// Metadata routines
// ==========================================================
static BOOL
ReadMetadata(png_structp png_ptr, png_infop info_ptr, FIBITMAP *dib) {
// XMP keyword
const char *g_png_xmp_keyword = "XML:com.adobe.xmp";
FITAG *tag = NULL;
png_textp text_ptr = NULL;
png_timep mod_time = NULL;
int num_text = 0;
// iTXt/tEXt/zTXt chuncks
if(png_get_text(png_ptr, info_ptr, &text_ptr, &num_text) > 0) {
for(int i = 0; i < num_text; i++) {
// create a tag
tag = FreeImage_CreateTag();
if(!tag) return FALSE;
DWORD tag_length = (DWORD) MAX(text_ptr[i].text_length, text_ptr[i].itxt_length);
FreeImage_SetTagLength(tag, tag_length);
FreeImage_SetTagCount(tag, tag_length);
FreeImage_SetTagType(tag, FIDT_ASCII);
FreeImage_SetTagValue(tag, text_ptr[i].text);
if(strcmp(text_ptr[i].key, g_png_xmp_keyword) == 0) {
// store the tag as XMP
FreeImage_SetTagKey(tag, g_TagLib_XMPFieldName);
FreeImage_SetMetadata(FIMD_XMP, dib, FreeImage_GetTagKey(tag), tag);
} else {
// store the tag as a comment
FreeImage_SetTagKey(tag, text_ptr[i].key);
FreeImage_SetMetadata(FIMD_COMMENTS, dib, FreeImage_GetTagKey(tag), tag);
}
// destroy the tag
FreeImage_DeleteTag(tag);
}
}
// timestamp chunk
if(png_get_tIME(png_ptr, info_ptr, &mod_time)) {
char timestamp[32];
// create a tag
tag = FreeImage_CreateTag();
if(!tag) return FALSE;
// convert as 'yyyy:MM:dd hh:mm:ss'
sprintf(timestamp, "%4d:%02d:%02d %2d:%02d:%02d", mod_time->year, mod_time->month, mod_time->day, mod_time->hour, mod_time->minute, mod_time->second);
DWORD tag_length = (DWORD)strlen(timestamp) + 1;
FreeImage_SetTagLength(tag, tag_length);
src/Source/FreeImage/PluginPNG.cpp view on Meta::CPAN
FreeImage_SetMetadata(FIMD_EXIF_MAIN, dib, FreeImage_GetTagKey(tag), tag);
// destroy the tag
FreeImage_DeleteTag(tag);
}
return TRUE;
}
static BOOL
WriteMetadata(png_structp png_ptr, png_infop info_ptr, FIBITMAP *dib) {
// XMP keyword
const char *g_png_xmp_keyword = "XML:com.adobe.xmp";
FITAG *tag = NULL;
FIMETADATA *mdhandle = NULL;
BOOL bResult = TRUE;
png_text text_metadata;
png_time mod_time;
// set the 'Comments' metadata as iTXt chuncks
mdhandle = FreeImage_FindFirstMetadata(FIMD_COMMENTS, dib, &tag);
if(mdhandle) {
do {
memset(&text_metadata, 0, sizeof(png_text));
text_metadata.compression = 1; // iTXt, none
text_metadata.key = (char*)FreeImage_GetTagKey(tag); // keyword, 1-79 character description of "text"
text_metadata.text = (char*)FreeImage_GetTagValue(tag); // comment, may be an empty string (ie "")
text_metadata.text_length = FreeImage_GetTagLength(tag);// length of the text string
text_metadata.itxt_length = FreeImage_GetTagLength(tag);// length of the itxt string
text_metadata.lang = 0; // language code, 0-79 characters or a NULL pointer
text_metadata.lang_key = 0; // keyword translated UTF-8 string, 0 or more chars or a NULL pointer
// set the tag
png_set_text(png_ptr, info_ptr, &text_metadata, 1);
} while(FreeImage_FindNextMetadata(mdhandle, &tag));
FreeImage_FindCloseMetadata(mdhandle);
bResult &= TRUE;
}
// set the 'XMP' metadata as iTXt chuncks
tag = NULL;
FreeImage_GetMetadata(FIMD_XMP, dib, g_TagLib_XMPFieldName, &tag);
if(tag && FreeImage_GetTagLength(tag)) {
memset(&text_metadata, 0, sizeof(png_text));
text_metadata.compression = 1; // iTXt, none
text_metadata.key = (char*)g_png_xmp_keyword; // keyword, 1-79 character description of "text"
text_metadata.text = (char*)FreeImage_GetTagValue(tag); // comment, may be an empty string (ie "")
text_metadata.text_length = FreeImage_GetTagLength(tag);// length of the text string
text_metadata.itxt_length = FreeImage_GetTagLength(tag);// length of the itxt string
text_metadata.lang = 0; // language code, 0-79 characters or a NULL pointer
text_metadata.lang_key = 0; // keyword translated UTF-8 string, 0 or more chars or a NULL pointer
// set the tag
png_set_text(png_ptr, info_ptr, &text_metadata, 1);
bResult &= TRUE;
}
// set the Exif-TIFF 'DateTime' metadata as a tIME chunk
tag = NULL;
FreeImage_GetMetadata(FIMD_EXIF_MAIN, dib, "DateTime", &tag);
if(tag && FreeImage_GetTagLength(tag)) {
int year, month, day, hour, minute, second;
const char *value = (char*)FreeImage_GetTagValue(tag);
if(sscanf(value, "%4d:%02d:%02d %2d:%02d:%02d", &year, &month, &day, &hour, &minute, &second) == 6) {
mod_time.year = (png_uint_16)year;
mod_time.month = (png_byte)month;
mod_time.day = (png_byte)day;
mod_time.hour = (png_byte)hour;
mod_time.minute = (png_byte)minute;
mod_time.second = (png_byte)second;
png_set_tIME (png_ptr, info_ptr, &mod_time);
}
}
return bResult;
}
// ==========================================================
// Plugin Interface
// ==========================================================
src/Source/FreeImage/PluginPNG.cpp view on Meta::CPAN
return "PNG";
}
static const char * DLL_CALLCONV
Description() {
return "Portable Network Graphics";
}
static const char * DLL_CALLCONV
Extension() {
return "png";
}
static const char * DLL_CALLCONV
RegExpr() {
return "^.PNG\r";
}
static const char * DLL_CALLCONV
MimeType() {
return "image/png";
}
static BOOL DLL_CALLCONV
Validate(FreeImageIO *io, fi_handle handle) {
BYTE png_signature[8] = { 137, 80, 78, 71, 13, 10, 26, 10 };
BYTE signature[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
io->read_proc(&signature, 1, 8, handle);
return (memcmp(png_signature, signature, 8) == 0);
}
static BOOL DLL_CALLCONV
SupportsExportDepth(int depth) {
return (
(depth == 1) ||
(depth == 4) ||
(depth == 8) ||
(depth == 24) ||
(depth == 32)
src/Source/FreeImage/PluginPNG.cpp view on Meta::CPAN
static BOOL DLL_CALLCONV
SupportsNoPixels() {
return TRUE;
}
// --------------------------------------------------------------------------
/**
Configure the decoder so that decoded pixels are compatible with a FREE_IMAGE_TYPE format.
Set conversion instructions as needed.
@param png_ptr PNG handle
@param info_ptr PNG info handle
@param flags Decoder flags
@param output_image_type Returned FreeImage converted image type
@return Returns TRUE if successful, returns FALSE otherwise
@see png_read_update_info
*/
static BOOL
ConfigureDecoder(png_structp png_ptr, png_infop info_ptr, int flags, FREE_IMAGE_TYPE *output_image_type) {
// get original image info
const int color_type = png_get_color_type(png_ptr, info_ptr);
const int bit_depth = png_get_bit_depth(png_ptr, info_ptr);
const int pixel_depth = bit_depth * png_get_channels(png_ptr, info_ptr);
FREE_IMAGE_TYPE image_type = FIT_BITMAP; // assume standard image type
// check for transparency table or single transparent color
BOOL bIsTransparent = png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS) == PNG_INFO_tRNS ? TRUE : FALSE;
// check allowed combinations of colour type and bit depth
// then get converted FreeImage type
switch(color_type) {
case PNG_COLOR_TYPE_GRAY: // color type '0', bitdepth = 1, 2, 4, 8, 16
switch(bit_depth) {
case 1:
case 2:
case 4:
case 8:
// expand grayscale images to the full 8-bit from 2-bit/pixel
if (pixel_depth == 2) {
png_set_expand_gray_1_2_4_to_8(png_ptr);
}
// if a tRNS chunk is provided, we must also expand the grayscale data to 8-bits,
// this allows us to make use of the transparency table with existing FreeImage methods
if (bIsTransparent && (pixel_depth < 8)) {
png_set_expand_gray_1_2_4_to_8(png_ptr);
}
break;
case 16:
image_type = (pixel_depth == 16) ? FIT_UINT16 : FIT_UNKNOWN;
// 16-bit grayscale images can contain a transparent value (shade)
// if found, expand the transparent value to a full alpha channel
if (bIsTransparent && (image_type != FIT_UNKNOWN)) {
// expand tRNS to a full alpha channel
png_set_tRNS_to_alpha(png_ptr);
// expand new 16-bit gray + 16-bit alpha to full 64-bit RGBA
png_set_gray_to_rgb(png_ptr);
image_type = FIT_RGBA16;
}
break;
default:
image_type = FIT_UNKNOWN;
break;
}
break;
src/Source/FreeImage/PluginPNG.cpp view on Meta::CPAN
default:
image_type = FIT_UNKNOWN;
break;
}
// sometimes, 24- or 48-bit images may contain transparency information
// check for this use case and convert to an alpha-compatible format
if (bIsTransparent && (image_type != FIT_UNKNOWN)) {
// if the image is 24-bit RGB, mark it as 32-bit; if it is 48-bit, mark it as 64-bit
image_type = (pixel_depth == 24) ? FIT_BITMAP : (pixel_depth == 48) ? FIT_RGBA16 : FIT_UNKNOWN;
// expand tRNS chunk to alpha channel
png_set_tRNS_to_alpha(png_ptr);
}
break;
case PNG_COLOR_TYPE_PALETTE: // color type '3', bitdepth = 1, 2, 4, 8
switch(bit_depth) {
case 1:
case 2:
case 4:
case 8:
// expand palette images to the full 8 bits from 2 bits/pixel
if (pixel_depth == 2) {
png_set_packing(png_ptr);
}
// if a tRNS chunk is provided, we must also expand the palletized data to 8-bits,
// this allows us to make use of the transparency table with existing FreeImage methods
if (bIsTransparent && (pixel_depth < 8)) {
png_set_packing(png_ptr);
}
break;
default:
image_type = FIT_UNKNOWN;
break;
}
break;
case PNG_COLOR_TYPE_GRAY_ALPHA: // color type '4', bitdepth = 8, 16
src/Source/FreeImage/PluginPNG.cpp view on Meta::CPAN
case 16:
// 16-bit grayscale + 16-bit alpha => convert to 64-bit RGBA
image_type = (pixel_depth == 32) ? FIT_RGBA16 : FIT_UNKNOWN;
break;
default:
image_type = FIT_UNKNOWN;
break;
}
// expand 8-bit greyscale + 8-bit alpha to 32-bit
// expand 16-bit greyscale + 16-bit alpha to 64-bit
png_set_gray_to_rgb(png_ptr);
break;
case PNG_COLOR_TYPE_RGB_ALPHA: // color type '6', bitdepth = 8, 16
switch(bit_depth) {
case 8:
break;
case 16:
image_type = (pixel_depth == 64) ? FIT_RGBA16 : FIT_UNKNOWN;
break;
default:
src/Source/FreeImage/PluginPNG.cpp view on Meta::CPAN
// check for unknown or invalid formats
if(image_type == FIT_UNKNOWN) {
*output_image_type = image_type;
return FALSE;
}
#ifndef FREEIMAGE_BIGENDIAN
if((image_type == FIT_UINT16) || (image_type == FIT_RGB16) || (image_type == FIT_RGBA16)) {
// turn on 16-bit byte swapping
png_set_swap(png_ptr);
}
#endif
#if FREEIMAGE_COLORORDER == FREEIMAGE_COLORORDER_BGR
if((image_type == FIT_BITMAP) && ((color_type == PNG_COLOR_TYPE_RGB) || (color_type == PNG_COLOR_TYPE_RGB_ALPHA))) {
// flip the RGB pixels to BGR (or RGBA to BGRA)
png_set_bgr(png_ptr);
}
#endif
// gamma correction
// unlike the example in the libpng documentation, we have *no* idea where
// this file may have come from--so if it doesn't have a file gamma, don't
// do any correction ("do no harm")
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_gAMA)) {
double gamma = 0;
double screen_gamma = 2.2;
if (png_get_gAMA(png_ptr, info_ptr, &gamma) && ( flags & PNG_IGNOREGAMMA ) != PNG_IGNOREGAMMA) {
png_set_gamma(png_ptr, screen_gamma, gamma);
}
}
// all transformations have been registered; now update info_ptr data
png_read_update_info(png_ptr, info_ptr);
// return the output image type
*output_image_type = image_type;
return TRUE;
}
static FIBITMAP * DLL_CALLCONV
Load(FreeImageIO *io, fi_handle handle, int page, int flags, void *data) {
png_structp png_ptr = NULL;
png_infop info_ptr = NULL;
png_uint_32 width, height;
int color_type;
int bit_depth;
int pixel_depth = 0; // pixel_depth = bit_depth * channels
FIBITMAP *dib = NULL;
png_bytepp row_pointers = NULL;
fi_ioStructure fio;
fio.s_handle = handle;
fio.s_io = io;
if (handle) {
BOOL header_only = (flags & FIF_LOAD_NOPIXELS) == FIF_LOAD_NOPIXELS;
try {
// check to see if the file is in fact a PNG file
BYTE png_check[PNG_BYTES_TO_CHECK];
io->read_proc(png_check, PNG_BYTES_TO_CHECK, 1, handle);
if (png_sig_cmp(png_check, (png_size_t)0, PNG_BYTES_TO_CHECK) != 0) {
return NULL; // Bad signature
}
// create the chunk manage structure
png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, (png_voidp)NULL, error_handler, warning_handler);
if (!png_ptr) {
return NULL;
}
// create the info structure
info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr) {
png_destroy_read_struct(&png_ptr, (png_infopp)NULL, (png_infopp)NULL);
return NULL;
}
// init the IO
png_set_read_fn(png_ptr, &fio, _ReadProc);
if (setjmp(png_jmpbuf(png_ptr))) {
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
return NULL;
}
// because we have already read the signature...
png_set_sig_bytes(png_ptr, PNG_BYTES_TO_CHECK);
// read the IHDR chunk
png_read_info(png_ptr, info_ptr);
png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, NULL, NULL, NULL);
// configure the decoder
FREE_IMAGE_TYPE image_type = FIT_BITMAP;
if(!ConfigureDecoder(png_ptr, info_ptr, flags, &image_type)) {
throw FI_MSG_ERROR_UNSUPPORTED_FORMAT;
}
// update image info
color_type = png_get_color_type(png_ptr, info_ptr);
bit_depth = png_get_bit_depth(png_ptr, info_ptr);
pixel_depth = bit_depth * png_get_channels(png_ptr, info_ptr);
// create a dib and write the bitmap header
// set up the dib palette, if needed
switch (color_type) {
case PNG_COLOR_TYPE_RGB:
case PNG_COLOR_TYPE_RGB_ALPHA:
dib = FreeImage_AllocateHeaderT(header_only, image_type, width, height, pixel_depth, FI_RGBA_RED_MASK, FI_RGBA_GREEN_MASK, FI_RGBA_BLUE_MASK);
break;
case PNG_COLOR_TYPE_PALETTE:
dib = FreeImage_AllocateHeaderT(header_only, image_type, width, height, pixel_depth, FI_RGBA_RED_MASK, FI_RGBA_GREEN_MASK, FI_RGBA_BLUE_MASK);
if(dib) {
png_colorp png_palette = NULL;
int palette_entries = 0;
png_get_PLTE(png_ptr,info_ptr, &png_palette, &palette_entries);
palette_entries = MIN((unsigned)palette_entries, FreeImage_GetColorsUsed(dib));
// store the palette
RGBQUAD *palette = FreeImage_GetPalette(dib);
for(int i = 0; i < palette_entries; i++) {
palette[i].rgbRed = png_palette[i].red;
palette[i].rgbGreen = png_palette[i].green;
palette[i].rgbBlue = png_palette[i].blue;
}
}
break;
case PNG_COLOR_TYPE_GRAY:
dib = FreeImage_AllocateHeaderT(header_only, image_type, width, height, pixel_depth, FI_RGBA_RED_MASK, FI_RGBA_GREEN_MASK, FI_RGBA_BLUE_MASK);
if(dib && (pixel_depth <= 8)) {
RGBQUAD *palette = FreeImage_GetPalette(dib);
const int palette_entries = 1 << pixel_depth;
src/Source/FreeImage/PluginPNG.cpp view on Meta::CPAN
default:
throw FI_MSG_ERROR_UNSUPPORTED_FORMAT;
}
if(!dib) {
throw FI_MSG_ERROR_DIB_MEMORY;
}
// store the transparency table
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) {
// array of alpha (transparency) entries for palette
png_bytep trans_alpha = NULL;
// number of transparent entries
int num_trans = 0;
// graylevel or color sample values of the single transparent color for non-paletted images
png_color_16p trans_color = NULL;
png_get_tRNS(png_ptr, info_ptr, &trans_alpha, &num_trans, &trans_color);
if((color_type == PNG_COLOR_TYPE_GRAY) && trans_color) {
// single transparent color
if (trans_color->gray < 256) {
BYTE table[256];
memset(table, 0xFF, 256);
table[trans_color->gray] = 0;
FreeImage_SetTransparencyTable(dib, table, 256);
}
// check for a full transparency table, too
src/Source/FreeImage/PluginPNG.cpp view on Meta::CPAN
}
} else if((color_type == PNG_COLOR_TYPE_PALETTE) && trans_alpha) {
// transparency table
FreeImage_SetTransparencyTable(dib, (BYTE *)trans_alpha, num_trans);
}
}
// store the background color (only supported for FIT_BITMAP types)
if ((image_type == FIT_BITMAP) && png_get_valid(png_ptr, info_ptr, PNG_INFO_bKGD)) {
// Get the background color to draw transparent and alpha images over.
// Note that even if the PNG file supplies a background, you are not required to
// use it - you should use the (solid) application background if it has one.
png_color_16p image_background = NULL;
RGBQUAD rgbBkColor;
if (png_get_bKGD(png_ptr, info_ptr, &image_background)) {
rgbBkColor.rgbRed = (BYTE)image_background->red;
rgbBkColor.rgbGreen = (BYTE)image_background->green;
rgbBkColor.rgbBlue = (BYTE)image_background->blue;
rgbBkColor.rgbReserved = 0;
FreeImage_SetBackgroundColor(dib, &rgbBkColor);
}
}
// get physical resolution
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_pHYs)) {
png_uint_32 res_x, res_y;
// we'll overload this var and use 0 to mean no phys data,
// since if it's not in meters we can't use it anyway
int res_unit_type = PNG_RESOLUTION_UNKNOWN;
png_get_pHYs(png_ptr,info_ptr, &res_x, &res_y, &res_unit_type);
if (res_unit_type == PNG_RESOLUTION_METER) {
FreeImage_SetDotsPerMeterX(dib, res_x);
FreeImage_SetDotsPerMeterY(dib, res_y);
}
}
// get possible ICC profile
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_iCCP)) {
png_charp profile_name = NULL;
png_bytep profile_data = NULL;
png_uint_32 profile_length = 0;
int compression_type;
png_get_iCCP(png_ptr, info_ptr, &profile_name, &compression_type, &profile_data, &profile_length);
// copy ICC profile data (must be done after FreeImage_AllocateHeader)
FreeImage_CreateICCProfile(dib, profile_data, profile_length);
}
// --- header only mode => clean-up and return
if (header_only) {
// get possible metadata (it can be located both before and after the image data)
ReadMetadata(png_ptr, info_ptr, dib);
if (png_ptr) {
// clean up after the read, and free any memory allocated - REQUIRED
png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
}
return dib;
}
// set the individual row_pointers to point at the correct offsets
row_pointers = (png_bytepp)malloc(height * sizeof(png_bytep));
if (!row_pointers) {
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
FreeImage_Unload(dib);
return NULL;
}
// read in the bitmap bits via the pointer table
// allow loading of PNG with minor errors (such as images with several IDAT chunks)
for (png_uint_32 k = 0; k < height; k++) {
row_pointers[height - 1 - k] = FreeImage_GetScanLine(dib, k);
}
png_set_benign_errors(png_ptr, 1);
png_read_image(png_ptr, row_pointers);
// check if the bitmap contains transparency, if so enable it in the header
if (FreeImage_GetBPP(dib) == 32) {
if (FreeImage_GetColorType(dib) == FIC_RGBALPHA) {
FreeImage_SetTransparent(dib, TRUE);
} else {
FreeImage_SetTransparent(dib, FALSE);
}
}
// cleanup
if (row_pointers) {
free(row_pointers);
row_pointers = NULL;
}
// read the rest of the file, getting any additional chunks in info_ptr
png_read_end(png_ptr, info_ptr);
// get possible metadata (it can be located both before and after the image data)
ReadMetadata(png_ptr, info_ptr, dib);
if (png_ptr) {
// clean up after the read, and free any memory allocated - REQUIRED
png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
}
return dib;
} catch (const char *text) {
if (png_ptr) {
png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);
}
if (row_pointers) {
free(row_pointers);
}
if (dib) {
FreeImage_Unload(dib);
}
FreeImage_OutputMessageProc(s_format_id, text);
return NULL;
}
}
return NULL;
}
// --------------------------------------------------------------------------
static BOOL DLL_CALLCONV
Save(FreeImageIO *io, FIBITMAP *dib, fi_handle handle, int page, int flags, void *data) {
png_structp png_ptr;
png_infop info_ptr;
png_colorp palette = NULL;
png_uint_32 width, height;
BOOL has_alpha_channel = FALSE;
RGBQUAD *pal; // pointer to dib palette
int bit_depth, pixel_depth; // pixel_depth = bit_depth * channels
int palette_entries;
int interlace_type;
fi_ioStructure fio;
fio.s_handle = handle;
fio.s_io = io;
if ((dib) && (handle)) {
try {
// create the chunk manage structure
png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, (png_voidp)NULL, error_handler, warning_handler);
if (!png_ptr) {
return FALSE;
}
// allocate/initialize the image information data.
info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr) {
png_destroy_write_struct(&png_ptr, (png_infopp)NULL);
return FALSE;
}
// Set error handling. REQUIRED if you aren't supplying your own
// error handling functions in the png_create_write_struct() call.
if (setjmp(png_jmpbuf(png_ptr))) {
// if we get here, we had a problem reading the file
png_destroy_write_struct(&png_ptr, &info_ptr);
return FALSE;
}
// init the IO
png_set_write_fn(png_ptr, &fio, _WriteProc, _FlushProc);
// set physical resolution
png_uint_32 res_x = (png_uint_32)FreeImage_GetDotsPerMeterX(dib);
png_uint_32 res_y = (png_uint_32)FreeImage_GetDotsPerMeterY(dib);
if ((res_x > 0) && (res_y > 0)) {
png_set_pHYs(png_ptr, info_ptr, res_x, res_y, PNG_RESOLUTION_METER);
}
// Set the image information here. Width and height are up to 2^31,
// bit_depth is one of 1, 2, 4, 8, or 16, but valid values also depend on
// the color_type selected. color_type is one of PNG_COLOR_TYPE_GRAY,
// PNG_COLOR_TYPE_GRAY_ALPHA, PNG_COLOR_TYPE_PALETTE, PNG_COLOR_TYPE_RGB,
// or PNG_COLOR_TYPE_RGB_ALPHA. interlace is either PNG_INTERLACE_NONE or
// PNG_INTERLACE_ADAM7, and the compression_type and filter_type MUST
// currently be PNG_COMPRESSION_TYPE_BASE and PNG_FILTER_TYPE_BASE. REQUIRED
src/Source/FreeImage/PluginPNG.cpp view on Meta::CPAN
if( (flags & PNG_INTERLACED) == PNG_INTERLACED) {
interlace_type = PNG_INTERLACE_ADAM7;
bInterlaced = TRUE;
} else {
interlace_type = PNG_INTERLACE_NONE;
}
// set the ZLIB compression level or default to PNG default compression level (ZLIB level = 6)
int zlib_level = flags & 0x0F;
if((zlib_level >= 1) && (zlib_level <= 9)) {
png_set_compression_level(png_ptr, zlib_level);
} else if((flags & PNG_Z_NO_COMPRESSION) == PNG_Z_NO_COMPRESSION) {
png_set_compression_level(png_ptr, Z_NO_COMPRESSION);
}
// filtered strategy works better for high color images
if(pixel_depth >= 16){
png_set_compression_strategy(png_ptr, Z_FILTERED);
png_set_filter(png_ptr, 0, PNG_FILTER_NONE|PNG_FILTER_SUB|PNG_FILTER_PAETH);
} else {
png_set_compression_strategy(png_ptr, Z_DEFAULT_STRATEGY);
}
FREE_IMAGE_TYPE image_type = FreeImage_GetImageType(dib);
if(image_type == FIT_BITMAP) {
// standard image type
bit_depth = (pixel_depth > 8) ? 8 : pixel_depth;
} else {
// 16-bit greyscale or 16-bit RGB(A)
bit_depth = 16;
}
// check for transparent images
BOOL bIsTransparent =
(image_type == FIT_BITMAP) && FreeImage_IsTransparent(dib) && (FreeImage_GetTransparencyCount(dib) > 0) ? TRUE : FALSE;
switch (FreeImage_GetColorType(dib)) {
case FIC_MINISWHITE:
if(!bIsTransparent) {
// Invert monochrome files to have 0 as black and 1 as white (no break here)
png_set_invert_mono(png_ptr);
}
// (fall through)
case FIC_MINISBLACK:
if(!bIsTransparent) {
png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
PNG_COLOR_TYPE_GRAY, interlace_type,
PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
break;
}
// If a monochrome image is transparent, save it with a palette
// (fall through)
case FIC_PALETTE:
{
png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
PNG_COLOR_TYPE_PALETTE, interlace_type,
PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
// set the palette
palette_entries = 1 << bit_depth;
palette = (png_colorp)png_malloc(png_ptr, palette_entries * sizeof (png_color));
pal = FreeImage_GetPalette(dib);
for (int i = 0; i < palette_entries; i++) {
palette[i].red = pal[i].rgbRed;
palette[i].green = pal[i].rgbGreen;
palette[i].blue = pal[i].rgbBlue;
}
png_set_PLTE(png_ptr, info_ptr, palette, palette_entries);
// You must not free palette here, because png_set_PLTE only makes a link to
// the palette that you malloced. Wait until you are about to destroy
// the png structure.
break;
}
case FIC_RGBALPHA :
has_alpha_channel = TRUE;
png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
PNG_COLOR_TYPE_RGBA, interlace_type,
PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
#if FREEIMAGE_COLORORDER == FREEIMAGE_COLORORDER_BGR
// flip BGR pixels to RGB
if(image_type == FIT_BITMAP) {
png_set_bgr(png_ptr);
}
#endif
break;
case FIC_RGB:
png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth,
PNG_COLOR_TYPE_RGB, interlace_type,
PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
#if FREEIMAGE_COLORORDER == FREEIMAGE_COLORORDER_BGR
// flip BGR pixels to RGB
if(image_type == FIT_BITMAP) {
png_set_bgr(png_ptr);
}
#endif
break;
case FIC_CMYK:
break;
}
// write possible ICC profile
FIICCPROFILE *iccProfile = FreeImage_GetICCProfile(dib);
if (iccProfile->size && iccProfile->data) {
png_set_iCCP(png_ptr, info_ptr, "Embedded Profile", 0, (png_const_bytep)iccProfile->data, iccProfile->size);
}
// write metadata
WriteMetadata(png_ptr, info_ptr, dib);
// Optional gamma chunk is strongly suggested if you have any guess
// as to the correct gamma of the image.
// png_set_gAMA(png_ptr, info_ptr, gamma);
// set the transparency table
if (bIsTransparent) {
png_set_tRNS(png_ptr, info_ptr, FreeImage_GetTransparencyTable(dib), FreeImage_GetTransparencyCount(dib), NULL);
}
// set the background color
if(FreeImage_HasBackgroundColor(dib)) {
png_color_16 image_background;
RGBQUAD rgbBkColor;
FreeImage_GetBackgroundColor(dib, &rgbBkColor);
memset(&image_background, 0, sizeof(png_color_16));
image_background.blue = rgbBkColor.rgbBlue;
image_background.green = rgbBkColor.rgbGreen;
image_background.red = rgbBkColor.rgbRed;
image_background.index = rgbBkColor.rgbReserved;
png_set_bKGD(png_ptr, info_ptr, &image_background);
}
// Write the file header information.
png_write_info(png_ptr, info_ptr);
// write out the image data
#ifndef FREEIMAGE_BIGENDIAN
if (bit_depth == 16) {
// turn on 16 bit byte swapping
png_set_swap(png_ptr);
}
#endif
int number_passes = 1;
if (bInterlaced) {
number_passes = png_set_interlace_handling(png_ptr);
}
if ((pixel_depth == 32) && (!has_alpha_channel)) {
BYTE *buffer = (BYTE *)malloc(width * 3);
// transparent conversion to 24-bit
// the number of passes is either 1 for non-interlaced images, or 7 for interlaced images
for (int pass = 0; pass < number_passes; pass++) {
for (png_uint_32 k = 0; k < height; k++) {
FreeImage_ConvertLine32To24(buffer, FreeImage_GetScanLine(dib, height - k - 1), width);
png_write_row(png_ptr, buffer);
}
}
free(buffer);
} else {
// the number of passes is either 1 for non-interlaced images, or 7 for interlaced images
for (int pass = 0; pass < number_passes; pass++) {
for (png_uint_32 k = 0; k < height; k++) {
png_write_row(png_ptr, FreeImage_GetScanLine(dib, height - k - 1));
}
}
}
// It is REQUIRED to call this to finish writing the rest of the file
// Bug with png_flush
png_write_end(png_ptr, info_ptr);
// clean up after the write, and free any memory allocated
if (palette) {
png_free(png_ptr, palette);
}
png_destroy_write_struct(&png_ptr, &info_ptr);
return TRUE;
} catch (const char *text) {
if(png_ptr) {
png_destroy_write_struct(&png_ptr, &info_ptr);
}
FreeImage_OutputMessageProc(s_format_id, text);
}
}
return FALSE;
}
// ==========================================================
// Init
src/Source/LibOpenJPEG/INSTALL view on Meta::CPAN
If it does not work, try adding the following flag to the cmake command :
'-DCMAKE_OSX_ARCHITECTURES:STRING=i386'
WINDOWS
-------
You can use cmake to generate project files for the IDE you are using (VS2010, NMake, etc).
Type 'cmake --help' for available generators on your platform.
Make sure to build the third party libs (png, zlib ...):
'-DBUILD_THIRDPARTY:BOOL=ON'
src/Source/LibPNG/ANNOUNCE view on Meta::CPAN
Libpng 1.6.16 - December 22, 2014
This is a public release of libpng, intended for use in production codes.
Files available for download:
Source files with LF line endings (for Unix/Linux) and with a
"configure" script
libpng-1.6.16.tar.xz (LZMA-compressed, recommended)
libpng-1.6.16.tar.gz
Source files with CRLF line endings (for Windows), without the
"configure" script
lpng1616.7z (LZMA-compressed, recommended)
lpng1616.zip
Other information:
libpng-1.6.16-README.txt
libpng-1.6.16-LICENSE.txt
libpng-1.6.16-*.asc (armored detached GPG signatures)
Changes since the last public release (1.6.15):
Added ".align 2" to arm/filter_neon.S to support old GAS assemblers that
don't do alignment correctly.
Revised Makefile.am and scripts/*.dfn to work with MinGW/MSYS;
renamed scripts/*.dfn to scripts/*.c (Bob Friesenhahn and John Bowler).
Quiet a "comparison always true" warning in pngstest.c (John Bowler).
Restored a test on width that was removed from png.c at libpng-1.6.9
(Bug report by Alex Eubanks).
Fixed an overflow in png_combine_row with very wide interlaced images.
Send comments/corrections/commendations to png-mng-implement at lists.sf.net
(subscription required; visit
https://lists.sourceforge.net/lists/listinfo/png-mng-implement
to subscribe)
or to glennrp at users.sourceforge.net
Glenn R-P
src/Source/LibPNG/CHANGES view on Meta::CPAN
CHANGES - changes for libpng
Version 0.2
added reader into png.h
fixed small problems in stub file
Version 0.3
added pull reader
split up pngwrite.c to several files
added pnglib.txt
added example.c
cleaned up writer, adding a few new transformations
fixed some bugs in writer
interfaced with zlib 0.5
added K&R support
added check for 64 KB blocks for 16-bit machines
Version 0.4
cleaned up code and commented code
simplified time handling into png_time
created png_color_16 and png_color_8 to handle color needs
cleaned up color type defines
fixed various bugs
made various names more consistent
interfaced with zlib 0.71
cleaned up zTXt reader and writer (using zlib's Reset functions)
split transformations into pngrtran.c and pngwtran.c
Version 0.5
interfaced with zlib 0.8
fixed many reading and writing bugs
saved using 3 spaces instead of tabs
Version 0.6
added png_large_malloc() and png_large_free()
added png_size_t
cleaned up some compiler warnings
added png_start_read_image()
Version 0.7
cleaned up lots of bugs
finished dithering and other stuff
added test program
changed name from pnglib to libpng
Version 0.71 [June, 1995]
changed pngtest.png for zlib 0.93
fixed error in libpng.txt and example.c
Version 0.8
cleaned up some bugs
added png_set_filler()
split up pngstub.c into pngmem.c, pngio.c, and pngerror.c
added #define's to remove unwanted code
moved png_info_init() to png.c
added old_size into png_realloc()
added functions to manually set filtering and compression info
changed compression parameters based on image type
optimized filter selection code
added version info
changed external functions passing floats to doubles (k&r problems?)
put all the configurable stuff in pngconf.h
enabled png_set_shift to work with paletted images on read
added png_read_update_info() - updates info structure with transformations
Version 0.81 [August, 1995]
incorporated Tim Wegner's medium model code (thanks, Tim)
Version 0.82 [September, 1995]
[unspecified changes]
Version 0.85 [December, 1995]
added more medium model code (almost everything's a far)
added i/o, error, and memory callback functions
src/Source/LibPNG/CHANGES view on Meta::CPAN
fixed other bugs introduced in 0.85 and 0.86
added some minor documentation
Version 0.88 [January, 1996]
fixed progressive bugs
replaced tabs with spaces
cleaned up documentation
added callbacks for read/write and warning/error functions
Version 0.89 [July, 1996]
Added new initialization API to make libpng work better with shared libs
we now have png_create_read_struct(), png_create_write_struct(),
png_create_info_struct(), png_destroy_read_struct(), and
png_destroy_write_struct() instead of the separate calls to
malloc and png_read_init(), png_info_init(), and png_write_init()
Changed warning/error callback functions to fix bug - this means you
should use the new initialization API if you were using the old
png_set_message_fn() calls, and that the old API no longer exists
so that people are aware that they need to change their code
Changed filter selection API to allow selection of multiple filters
since it didn't work in previous versions of libpng anyways
Optimized filter selection code
Fixed png_set_background() to allow using an arbitrary RGB color for
paletted images
Fixed gamma and background correction for paletted images, so
png_correct_palette is not needed unless you are correcting an
external palette (you will need to #define PNG_CORRECT_PALETTE_SUPPORTED
in pngconf.h) - if nobody uses this, it may disappear in the future.
Fixed bug with Borland 64K memory allocation (Alexander Lehmann)
Fixed bug in interlace handling (Smarasderagd, I think)
Added more error checking for writing and image to reduce invalid files
Separated read and write functions so that they won't both be linked
into a binary when only reading or writing functionality is used
New pngtest image also has interlacing and zTXt
Updated documentation to reflect new API
Version 0.90 [January, 1997]
Made CRC errors/warnings on critical and ancillary chunks configurable
libpng will use the zlib CRC routines by (compile-time) default
Changed DOS small/medium model memory support - needs zlib 1.04 (Tim Wegner)
Added external C++ wrapper statements to png.h (Gilles Dauphin)
Allow PNG file to be read when some or all of file signature has already
been read from the beginning of the stream. ****This affects the size
of info_struct and invalidates all programs that use a shared libpng****
Fixed png_filler() declarations
Fixed? background color conversions
Fixed order of error function pointers to match documentation
Current chunk name is now available in png_struct to reduce the number
of nearly identical error messages (will simplify multi-lingual
support when available)
Try to get ready for unknown-chunk callback functions:
- previously read critical chunks are flagged, so the chunk handling
routines can determine if the chunk is in the right place
- all chunk handling routines have the same prototypes, so we will
be able to handle all chunks via a callback mechanism
Try to fix Linux "setjmp" buffer size problems
Removed png_large_malloc, png_large_free, and png_realloc functions.
Version 0.95 [March, 1997]
Fixed bug in pngwutil.c allocating "up_row" twice and "avg_row" never
Fixed bug in PNG file signature compares when start != 0
Changed parameter type of png_set_filler(...filler...) from png_byte
to png_uint_32
Added test for MACOS to ensure that both math.h and fp.h are not #included
Added macros for libpng to be compiled as a Windows DLL (Andreas Kupries)
Added "packswap" transformation, which changes the endianness of
packed-pixel bytes (Kevin Bracey)
Added "strip_alpha" transformation, which removes the alpha channel of
input images without using it (not necessarily a good idea)
Added "swap_alpha" transformation, which puts the alpha channel in front
of the color bytes instead of after
Removed all implicit variable tests which assume NULL == 0 (I think)
Changed several variables to "png_size_t" to show 16/32-bit limitations
Added new pCAL chunk read/write support
Added experimental filter selection weighting (Greg Roelofs)
Removed old png_set_rgbx() and png_set_xrgb() functions that have been
obsolete for about 2 years now (use png_set_filler() instead)
Added macros to read 16- and 32-bit ints directly from buffer, to be
used only on those systems that support it (namely PowerPC and 680x0)
With some testing, this may become the default for MACOS/PPC systems.
Only calculate CRC on data if we are going to use it
Added macros for zTXt compression type PNG_zTXt_COMPRESSION_???
Added macros for simple libpng debugging output selectable at compile time
Removed PNG_READ_END_MODE in progressive reader (Smarasderagd)
More description of info_struct in libpng.txt and png.h
More instructions in example.c
More chunk types tested in pngtest.c
Renamed pngrcb.c to pngset.c, and all png_read_<chunk> functions to be
png_set_<chunk>. We now have corresponding png_get_<chunk>
functions in pngget.c to get information in info_ptr. This isolates
the application from the internal organization of png_info_struct
(good for shared library implementations).
Version 0.96 [May, 1997]
Fixed serious bug with < 8bpp images introduced in 0.95
Fixed 256-color transparency bug (Greg Roelofs)
Fixed up documentation (Greg Roelofs, Laszlo Nyul)
Fixed "error" in pngconf.h for Linux setjmp() behavior
Fixed DOS medium model support (Tim Wegner)
Fixed png_check_keyword() for case with error in static string text
Added read of CRC after IEND chunk for embedded PNGs (Laszlo Nyul)
Added typecasts to quiet compiler errors
Added more debugging info
Version 0.97 [January, 1998]
Removed PNG_USE_OWN_CRC capability
Relocated png_set_crc_action from pngrutil.c to pngrtran.c
Fixed typecasts of "new_key", etc. (Andreas Dilger)
Added RFC 1152 [sic] date support
Fixed bug in gamma handling of 4-bit grayscale
Added 2-bit grayscale gamma handling (Glenn R-P)
Added more typecasts. 65536L becomes (png_uint_32)65536L, etc. (Glenn R-P)
Minor corrections in libpng.txt
Added simple sRGB support (Glenn R-P)
Easier conditional compiling, e.g.,
define PNG_READ/WRITE_NOT_FULLY_SUPPORTED;
all configurable options can be selected from command-line instead
of having to edit pngconf.h (Glenn R-P)
Fixed memory leak in pngwrite.c (free info_ptr->text) (Glenn R-P)
Added more conditions for png_do_background, to avoid changing
black pixels to background when a background is supplied and
no pixels are transparent
Repaired PNG_NO_STDIO behavior
Tested NODIV support and made it default behavior (Greg Roelofs)
Added "-m" option and PNGTEST_DEBUG_MEMORY to pngtest (John Bowler)
Regularized version numbering scheme and bumped shared-library major
version number to 2 to avoid problems with libpng 0.89 apps
(Greg Roelofs)
Version 0.98 [January, 1998]
Cleaned up some typos in libpng.txt and in code documentation
Fixed memory leaks in pCAL chunk processing (Glenn R-P and John Bowler)
Cosmetic change "display_gamma" to "screen_gamma" in pngrtran.c
Changed recommendation about file_gamma for PC images to .51 from .45,
in example.c and libpng.txt, added comments to distinguish between
screen_gamma, viewing_gamma, and display_gamma.
Changed all references to RFC1152 to read RFC1123 and changed the
PNG_TIME_RFC1152_SUPPORTED macro to PNG_TIME_RFC1123_SUPPORTED
Added png_invert_alpha capability (Glenn R-P -- suggestion by Jon Vincent)
Changed srgb_intent from png_byte to int to avoid compiler bugs
Version 0.99 [January 30, 1998]
Free info_ptr->text instead of end_info_ptr->text in pngread.c (John Bowler)
Fixed a longstanding "packswap" bug in pngtrans.c
Fixed some inconsistencies in pngconf.h that prevented compiling with
PNG_READ_GAMMA_SUPPORTED and PNG_READ_hIST_SUPPORTED undefined
Fixed some typos and made other minor rearrangement of libpng.txt (Andreas)
Changed recommendation about file_gamma for PC images to .50 from .51 in
example.c and libpng.txt, and changed file_gamma for sRGB images to .45
Added a number of functions to access information from the png structure
png_get_image_height(), etc. (Glenn R-P, suggestion by Brad Pettit)
Added TARGET_MACOS similar to zlib-1.0.8
Define PNG_ALWAYS_EXTERN when __MWERKS__ && WIN32 are defined
Added type casting to all png_malloc() function calls
Version 0.99a [January 31, 1998]
Added type casts and parentheses to all returns that return a value.(Tim W.)
Version 0.99b [February 4, 1998]
Added type cast png_uint_32 on malloc function calls where needed.
Changed type of num_hist from png_uint_32 to int (same as num_palette).
Added checks for rowbytes overflow, in case png_size_t is less than 32 bits.
Renamed makefile.elf to makefile.lnx.
Version 0.99c [February 7, 1998]
More type casting. Removed erroneous overflow test in pngmem.c.
Added png_buffered_memcpy() and png_buffered_memset(), apply them to rowbytes.
Added UNIX manual pages libpng.3 (incorporating libpng.txt) and png.5.
Version 0.99d [February 11, 1998]
Renamed "far_to_near()" "png_far_to_near()"
Revised libpng.3
Version 99c "buffered" operations didn't work as intended. Replaced them
with png_memcpy_check() and png_memset_check().
Added many "if (png_ptr == NULL) return" to quell compiler warnings about
unused png_ptr, mostly in pngget.c and pngset.c.
Check for overlength tRNS chunk present when indexed-color PLTE is read.
Cleaned up spelling errors in libpng.3/libpng.txt
Corrected a problem with png_get_tRNS() which returned undefined trans array
Version 0.99e [February 28, 1998]
Corrected png_get_tRNS() again.
Add parentheses for easier reading of pngget.c, fixed "||" should be "&&".
Touched up example.c to make more of it compileable, although the entire
file still can't be compiled (Willem van Schaik)
Fixed a bug in png_do_shift() (Bryan Tsai)
Added a space in png.h prototype for png_write_chunk_start()
Replaced pngtest.png with one created with zlib 1.1.1
Changed pngtest to report PASS even when file size is different (Jean-loup G.)
Corrected some logic errors in png_do_invert_alpha() (Chris Patterson)
Version 0.99f [March 5, 1998]
Corrected a bug in pngpread() introduced in version 99c (Kevin Bracey)
Moved makefiles into a "scripts" directory, and added INSTALL instruction file
Added makefile.os2 and pngos2.def (A. Zabolotny) and makefile.s2x (W. Sebok)
Added pointers to "note on libpng versions" in makefile.lnx and README
Added row callback feature when reading and writing nonprogressive rows
and added a test of this feature in pngtest.c
Added user transform callbacks, with test of the feature in pngtest.c
Version 0.99g [March 6, 1998, morning]
Minor changes to pngtest.c to suppress compiler warnings.
Removed "beta" language from documentation.
Version 0.99h [March 6, 1998, evening]
Minor changes to previous minor changes to pngtest.c
Changed PNG_READ_NOT_FULLY_SUPPORTED to PNG_READ_TRANSFORMS_NOT_SUPPORTED
and added PNG_PROGRESSIVE_READ_NOT_SUPPORTED macro
Added user transform capability
Version 1.00 [March 7, 1998]
Changed several typedefs in pngrutil.c
Added makefile.wat (Pawel Mrochen), updated makefile.tc3 (Willem van Schaik)
Replaced "while(1)" with "for(;;)"
Added PNGARG() to prototypes in pngtest.c and removed some prototypes
Updated some of the makefiles (Tom Lane)
Changed some typedefs (s_start, etc.) in pngrutil.c
Fixed dimensions of "short_months" array in pngwrite.c
Replaced ansi2knr.c with the one from jpeg-v6
Version 1.0.0 [March 8, 1998]
Changed name from 1.00 to 1.0.0 (Adam Costello)
Added smakefile.ppc (with SCOPTIONS.ppc) for Amiga PPC (Andreas Kleinert)
Version 1.0.0a [March 9, 1998]
Fixed three bugs in pngrtran.c to make gamma+background handling consistent
(Greg Roelofs)
Changed format of the PNG_LIBPNG_VER integer to xyyzz instead of xyz
for major, minor, and bugfix releases. This is 10001. (Adam Costello,
Tom Lane)
Make months range from 1-12 in png_convert_to_rfc1123
Version 1.0.0b [March 13, 1998]
Quieted compiler complaints about two empty "for" loops in pngrutil.c
Minor changes to makefile.s2x
Removed #ifdef/#endif around a png_free() in pngread.c
Version 1.0.1 [March 14, 1998]
Changed makefile.s2x to reduce security risk of using a relative pathname
Fixed some typos in the documentation (Greg).
Fixed a problem with value of "channels" returned by png_read_update_info()
Version 1.0.1a [April 21, 1998]
Optimized Paeth calculations by replacing abs() function calls with intrinsics
plus other loop optimizations. Improves avg decoding speed by about 20%.
Commented out i386istic "align" compiler flags in makefile.lnx.
Reduced the default warning level in some makefiles, to make them consistent.
Removed references to IJG and JPEG in the ansi2knr.c copyright statement.
Fixed a bug in png_do_strip_filler with XXRRGGBB => RRGGBB transformation.
Added grayscale and 16-bit capability to png_do_read_filler().
Fixed a bug in pngset.c, introduced in version 0.99c, that sets rowbytes
too large when writing an image with bit_depth < 8 (Bob Dellaca).
Corrected some bugs in the experimental weighted filtering heuristics.
Moved a misplaced pngrutil code block that truncates tRNS if it has more
than num_palette entries -- test was done before num_palette was defined.
Fixed a png_convert_to_rfc1123() bug that converts day 31 to 0 (Steve Eddins).
Changed compiler flags in makefile.wat for better optimization
(Pawel Mrochen).
Version 1.0.1b [May 2, 1998]
Relocated png_do_gray_to_rgb() within png_do_read_transformations() (Greg).
Relocated the png_composite macros from pngrtran.c to png.h (Greg).
Added makefile.sco (contributed by Mike Hopkirk).
Fixed two bugs (missing definitions of "istop") introduced in libpng-1.0.1a.
Fixed a bug in pngrtran.c that would set channels=5 under some circumstances.
More work on the Paeth-filtering, achieving imperceptible speedup
(A Kleinert).
More work on loop optimization which may help when compiled with C++
compilers.
Added warnings when people try to use transforms they've defined out.
Collapsed 4 "i" and "c" loops into single "i" loops in pngrtran and pngwtran.
Revised paragraph about png_set_expand() in libpng.txt and libpng.3 (Greg)
Version 1.0.1c [May 11, 1998]
Fixed a bug in pngrtran.c (introduced in libpng-1.0.1a) where the masks for
filler bytes should have been 0xff instead of 0xf.
Added max_pixel_depth=32 in pngrutil.c when using FILLER with palette images.
Moved PNG_WRITE_WEIGHTED_FILTER_SUPPORTED and PNG_WRITE_FLUSH_SUPPORTED
out of the PNG_WRITE_TRANSFORMS_NOT_SUPPORTED block of pngconf.h
Added "PNG_NO_WRITE_TRANSFORMS" etc., as alternatives for *_NOT_SUPPORTED,
for consistency, in pngconf.h
Added individual "ifndef PNG_NO_[CAPABILITY]" in pngconf.h to make it easier
to remove unwanted capabilities via the compile line
Made some corrections to grammar (which, it's) in documentation (Greg).
Corrected example.c, use of row_pointers in png_write_image().
Version 1.0.1d [May 24, 1998]
Corrected several statements that used side effects illegally in pngrutil.c
and pngtrans.c, that were introduced in version 1.0.1b
Revised png_read_rows() to avoid repeated if-testing for NULL (A Kleinert)
More corrections to example.c, use of row_pointers in png_write_image()
and png_read_rows().
Added pngdll.mak and pngdef.pas to scripts directory, contributed by
Bob Dellaca, to make a png32bd.dll with Borland C++ 4.5
Fixed error in example.c with png_set_text: num_text is 3, not 2 (Guido V.)
Changed several loops from count-down to count-up, for consistency.
Version 1.0.1e [June 6, 1998]
Revised libpng.txt and libpng.3 description of png_set_read|write_fn(), and
added warnings when people try to set png_read_fn and png_write_fn in
the same structure.
Added a test such that png_do_gamma will be done when num_trans==0
for truecolor images that have defined a background. This corrects an
error that was introduced in libpng-0.90 that can cause gamma processing
to be skipped.
Added tests in png.h to include "trans" and "trans_values" in structures
when PNG_READ_BACKGROUND_SUPPORTED or PNG_READ_EXPAND_SUPPORTED is defined.
Add png_free(png_ptr->time_buffer) in png_destroy_read_struct()
Moved png_convert_to_rfc_1123() from pngwrite.c to png.c
Added capability for user-provided malloc_fn() and free_fn() functions,
and revised pngtest.c to demonstrate their use, replacing the
PNGTEST_DEBUG_MEM feature.
Added makefile.w32, for Microsoft C++ 4.0 and later (Tim Wegner).
Version 1.0.2 [June 14, 1998]
Fixed two bugs in makefile.bor .
Version 1.0.2a [December 30, 1998]
Replaced and extended code that was removed from png_set_filler() in 1.0.1a.
Fixed a bug in png_do_filler() that made it fail to write filler bytes in
the left-most pixel of each row (Kevin Bracey).
Changed "static pngcharp tIME_string" to "static char tIME_string[30]"
in pngtest.c (Duncan Simpson).
Fixed a bug in pngtest.c that caused pngtest to try to write a tIME chunk
even when no tIME chunk was present in the source file.
Fixed a problem in pngrutil.c: gray_to_rgb didn't always work with 16-bit.
Fixed a problem in png_read_push_finish_row(), which would not skip some
passes that it should skip, for images that are less than 3 pixels high.
Interchanged the order of calls to png_do_swap() and png_do_shift()
in pngwtran.c (John Cromer).
Added #ifdef PNG_DEBUG/#endif surrounding use of PNG_DEBUG in png.h .
Changed "bad adaptive filter type" from error to warning in pngrutil.c .
Fixed a documentation error about default filtering with 8-bit indexed-color.
Separated the PNG_NO_STDIO macro into PNG_NO_STDIO and PNG_NO_CONSOLE_IO
(L. Peter Deutsch).
Added png_set_rgb_to_gray() and png_get_rgb_to_gray_status() functions.
Added png_get_copyright() and png_get_header_version() functions.
Revised comments on png_set_progressive_read_fn() in libpng.txt and example.c
Added information about debugging in libpng.txt and libpng.3 .
Changed "ln -sf" to "ln -s -f" in makefile.s2x, makefile.lnx, and
makefile.sco.
Removed lines after Dynamic Dependencies" in makefile.aco .
Revised makefile.dec to make a shared library (Jeremie Petit).
Removed trailing blanks from all files.
Version 1.0.2a [January 6, 1999]
Removed misplaced #endif and #ifdef PNG_NO_EXTERN near the end of png.h
Added "if" tests to silence complaints about unused png_ptr in png.h and png.c
Changed "check_if_png" function in example.c to return true (nonzero) if PNG.
Changed libpng.txt to demonstrate png_sig_cmp() instead of png_check_sig()
which is obsolete.
Version 1.0.3 [January 14, 1999]
Added makefile.hux, for Hewlett Packard HPUX 10.20 and 11.00 (Jim Rice)
Added a statement of Y2K compliance in png.h, libpng.3, and Y2KINFO.
Version 1.0.3a [August 12, 1999]
Added check for PNG_READ_INTERLACE_SUPPORTED in pngread.c; issue a warning
if an attempt is made to read an interlaced image when it's not supported.
Added check if png_ptr->trans is defined before freeing it in pngread.c
Modified the Y2K statement to include versions back to version 0.71
Fixed a bug in the check for valid IHDR bit_depth/color_types in pngrutil.c
Modified makefile.wat (added -zp8 flag, ".symbolic", changed some comments)
Replaced leading blanks with tab characters in makefile.hux
Changed "dworkin.wustl.edu" to "ccrc.wustl.edu" in various documents.
Changed (float)red and (float)green to (double)red, (double)green
in png_set_rgb_to_gray() to avoid "promotion" problems in AIX.
Fixed a bug in pngconf.h that omitted <stdio.h> when PNG_DEBUG==0 (K Bracey).
Reformatted libpng.3 and libpngpf.3 with proper fonts (script by J. vanZandt).
Updated documentation to refer to the PNG-1.2 specification.
Removed ansi2knr.c and left pointers to the latest source for ansi2knr.c
in makefile.knr, INSTALL, and README (L. Peter Deutsch)
Fixed bugs in calculation of the length of rowbytes when adding alpha
channels to 16-bit images, in pngrtran.c (Chris Nokleberg)
Added function png_set_user_transform_info() to store user_transform_ptr,
user_depth, and user_channels into the png_struct, and a function
png_get_user_transform_ptr() to retrieve the pointer (Chris Nokleberg)
Added function png_set_empty_plte_permitted() to make libpng useable
in MNG applications.
Corrected the typedef for png_free_ptr in png.h (Jesse Jones).
Correct gamma with srgb is 45455 instead of 45000 in pngrutil.c, to be
consistent with PNG-1.2, and allow variance of 500 before complaining.
Added assembler code contributed by Intel in file pngvcrd.c and modified
makefile.w32 to use it (Nirav Chhatrapati, INTEL Corporation,
Gilles Vollant)
Changed "ln -s -f" to "ln -f -s" in the makefiles to make Solaris happy.
Added some aliases for png_set_expand() in pngrtran.c, namely
png_set_expand_PLTE(), png_set_expand_depth(), and png_set_expand_tRNS()
(Greg Roelofs, in "PNG: The Definitive Guide").
Added makefile.beo for BEOS on X86, contributed by Sander Stok.
Version 1.0.3b [August 26, 1999]
Replaced 2147483647L several places with PNG_MAX_UINT macro, defined in png.h
Changed leading blanks to tabs in all makefiles.
Define PNG_USE_PNGVCRD in makefile.w32, to get MMX assembler code.
Made alternate versions of png_set_expand() in pngrtran.c, namely
png_set_gray_1_2_4_to_8, png_set_palette_to_rgb, and png_set_tRNS_to_alpha
(Greg Roelofs, in "PNG: The Definitive Guide"). Deleted the 1.0.3a aliases.
Relocated start of 'extern "C"' block in png.h so it doesn't include pngconf.h
Revised calculation of num_blocks in pngmem.c to avoid a potentially
negative shift distance, whose results are undefined in the C language.
Added a check in pngset.c to prevent writing multiple tIME chunks.
Added a check in pngwrite.c to detect invalid small window_bits sizes.
Version 1.0.3d [September 4, 1999]
Fixed type casting of igamma in pngrutil.c
Added new png_expand functions to scripts/pngdef.pas and pngos2.def
Added a demo read_user_transform_fn that examines the row filters in pngtest.c
Version 1.0.4 [September 24, 1999]
Define PNG_ALWAYS_EXTERN in pngconf.h if __STDC__ is defined
Delete #define PNG_INTERNAL and include "png.h" from pngasmrd.h
Made several minor corrections to pngtest.c
Renamed the makefiles with longer but more user friendly extensions.
Copied the PNG copyright and license to a separate LICENSE file.
Revised documentation, png.h, and example.c to remove reference to
"viewing_gamma" which no longer appears in the PNG specification.
Revised pngvcrd.c to use MMX code for interlacing only on the final pass.
Updated pngvcrd.c to use the faster C filter algorithms from libpng-1.0.1a
Split makefile.win32vc into two versions, makefile.vcawin32 (uses MMX
assembler code) and makefile.vcwin32 (doesn't).
Added a CPU timing report to pngtest.c (enabled by defining PNGTEST_TIMING)
Added a copy of pngnow.png to the distribution.
Version 1.0.4a [September 25, 1999]
Increase max_pixel_depth in pngrutil.c if a user transform needs it.
Changed several division operations to right-shifts in pngvcrd.c
Version 1.0.4b [September 30, 1999]
Added parentheses in line 3732 of pngvcrd.c
Added a comment in makefile.linux warning about buggy -O3 in pgcc 2.95.1
Version 1.0.4c [October 1, 1999]
Added a "png_check_version" function in png.c and pngtest.c that will generate
a helpful compiler error if an old png.h is found in the search path.
Changed type of png_user_transform_depth|channels from int to png_byte.
Version 1.0.4d [October 6, 1999]
Changed 0.45 to 0.45455 in png_set_sRGB()
Removed unused PLTE entries from pngnow.png
Re-enabled some parts of pngvcrd.c (png_combine_row) that work properly.
Version 1.0.4e [October 10, 1999]
Fixed sign error in pngvcrd.c (Greg Roelofs)
Replaced some instances of memcpy with simple assignments in pngvcrd (GR-P)
Version 1.0.4f [October 15, 1999]
Surrounded example.c code with #if 0 .. #endif to prevent people from
inadvertently trying to compile it.
Changed png_get_header_version() from a function to a macro in png.h
Added type casting mostly in pngrtran.c and pngwtran.c
Removed some pointless "ptr = NULL" in pngmem.c
Added a "contrib" directory containing the source code from Greg's book.
Version 1.0.5 [October 15, 1999]
Minor editing of the INSTALL and README files.
Version 1.0.5a [October 23, 1999]
Added contrib/pngsuite and contrib/pngminus (Willem van Schaik)
Fixed a typo in the png_set_sRGB() function call in example.c (Jan Nijtmans)
Further optimization and bugfix of pngvcrd.c
Revised pngset.c so that it does not allocate or free memory in the user's
text_ptr structure. Instead, it makes its own copy.
Created separate write_end_info_struct in pngtest.c for a more severe test.
Added code in pngwrite.c to free info_ptr->text[i].key to stop a memory leak.
Version 1.0.5b [November 23, 1999]
Moved PNG_FLAG_HAVE_CHUNK_HEADER, PNG_FLAG_BACKGROUND_IS_GRAY and
PNG_FLAG_WROTE_tIME from flags to mode.
Added png_write_info_before_PLTE() function.
Fixed some typecasting in contrib/gregbook/*.c
Updated scripts/makevms.com and added makevms.com to contrib/gregbook
and contrib/pngminus (Martin Zinser)
Version 1.0.5c [November 26, 1999]
Moved png_get_header_version from png.h to png.c, to accommodate ansi2knr.
Removed all global arrays (according to PNG_NO_GLOBAL_ARRAYS macro), to
accommodate making DLL's: Moved usr_png_ver from global variable to function
png_get_header_ver() in png.c. Moved png_sig to png_sig_bytes in png.c and
eliminated use of png_sig in pngwutil.c. Moved the various png_CHNK arrays
into pngtypes.h. Eliminated use of global png_pass arrays. Declared the
png_CHNK and png_pass arrays to be "const". Made the global arrays
available to applications (although none are used in libpng itself) when
PNG_NO_GLOBAL_ARRAYS is not defined or when PNG_GLOBAL_ARRAYS is defined.
Removed some extraneous "-I" from contrib/pngminus/makefile.std
Changed the PNG_sRGB_INTENT macros in png.h to be consistent with PNG-1.2.
Change PNG_SRGB_INTENT to PNG_sRGB_INTENT in libpng.txt and libpng.3
Version 1.0.5d [November 29, 1999]
Add type cast (png_const_charp) two places in png.c
Eliminated pngtypes.h; use macros instead to declare PNG_CHNK arrays.
Renamed "PNG_GLOBAL_ARRAYS" to "PNG_USE_GLOBAL_ARRAYS" and made available
to applications a macro "PNG_USE_LOCAL_ARRAYS".
comment out (with #ifdef) all the new declarations when
PNG_USE_GLOBAL_ARRAYS is defined.
Added PNG_EXPORT_VAR macro to accommodate making DLL's.
Version 1.0.5e [November 30, 1999]
Added iCCP, iTXt, and sPLT support; added "lang" member to the png_text
structure; refactored the inflate/deflate support to make adding new chunks
with trailing compressed parts easier in the future, and added new functions
png_free_iCCP, png_free_pCAL, png_free_sPLT, png_free_text, png_get_iCCP,
png_get_spalettes, png_set_iCCP, png_set_spalettes (Eric S. Raymond).
NOTE: Applications that write text chunks MUST define png_text->lang
before calling png_set_text(). It must be set to NULL if you want to
write tEXt or zTXt chunks. If you want your application to be able to
run with older versions of libpng, use
#ifdef PNG_iTXt_SUPPORTED
png_text[i].lang = NULL;
#endif
Changed png_get_oFFs() and png_set_oFFs() to use signed rather than unsigned
offsets (Eric S. Raymond).
Combined PNG_READ_cHNK_SUPPORTED and PNG_WRITE_cHNK_SUPPORTED macros into
PNG_cHNK_SUPPORTED and combined the three types of PNG_text_SUPPORTED
macros, leaving the separate macros also available.
Removed comments on #endifs at the end of many short, non-nested #if-blocks.
Version 1.0.5f [December 6, 1999]
Changed makefile.solaris to issue a warning about potential problems when
the ucb "ld" is in the path ahead of the ccs "ld".
Removed "- [date]" from the "synopsis" line in libpng.3 and libpngpf.3.
Added sCAL chunk support (Eric S. Raymond).
Version 1.0.5g [December 7, 1999]
Fixed "png_free_spallettes" typo in png.h
Added code to handle new chunks in pngpread.c
Moved PNG_CHNK string macro definitions outside of PNG_NO_EXTERN block
Added "translated_key" to png_text structure and png_write_iTXt().
Added code in pngwrite.c to work around a newly discovered zlib bug.
Version 1.0.5h [December 10, 1999]
NOTE: regarding the note for version 1.0.5e, the following must also
be included in your code:
png_text[i].translated_key = NULL;
Unknown chunk handling is now supported.
Option to eliminate all floating point support was added. Some new
fixed-point functions such as png_set_gAMA_fixed() were added.
Expanded tabs and removed trailing blanks in source files.
Version 1.0.5i [December 13, 1999]
Added some type casts to silence compiler warnings.
Renamed "png_free_spalette" to "png_free_spalettes" for consistency.
Removed leading blanks from a #define in pngvcrd.c
Added some parameters to the new png_set_keep_unknown_chunks() function.
Added a test for up->location != 0 in the first instance of writing
unknown chunks in pngwrite.c
Changed "num" to "i" in png_free_spalettes() and png_free_unknowns() to
prevent recursion.
Added png_free_hIST() function.
Various patches to fix bugs in the sCAL and integer cHRM processing,
and to add some convenience macros for use with sCAL.
Version 1.0.5j [December 21, 1999]
Changed "unit" parameter of png_write_sCAL from png_byte to int, to work
around buggy compilers.
Added new type "png_fixed_point" for integers that hold float*100000 values
Restored backward compatibility of tEXt/zTXt chunk processing:
Restored the first four members of png_text to the same order as v.1.0.5d.
Added members "lang_key" and "itxt_length" to png_text struct. Set
text_length=0 when "text" contains iTXt data. Use the "compression"
member to distinguish among tEXt/zTXt/iTXt types. Added
PNG_ITXT_COMPRESSION_NONE (1) and PNG_ITXT_COMPRESSION_zTXt(2) macros.
The "Note" above, about backward incompatibility of libpng-1.0.5e, no
longer applies.
Fixed png_read|write_iTXt() to read|write parameters in the right order,
and to write the iTXt chunk after IDAT if it appears in the end_ptr.
Added pnggccrd.c, version of pngvcrd.c Intel assembler for gcc (Greg Roelofs)
Reversed the order of trying to write floating-point and fixed-point gAMA.
Version 1.0.5k [December 27, 1999]
Added many parentheses, e.g., "if (a && b & c)" becomes "if (a && (b & c))"
Added png_handle_as_unknown() function (Glenn)
Added png_free_chunk_list() function and chunk_list and num_chunk_list members
of png_ptr.
Eliminated erroneous warnings about multiple sPLT chunks and sPLT-after-PLTE.
Fixed a libpng-1.0.5h bug in pngrutil.c that was issuing erroneous warnings
about ignoring incorrect gAMA with sRGB (gAMA was in fact not ignored)
Added png_free_tRNS(); png_set_tRNS() now malloc's its own trans array (ESR).
Define png_get_int_32 when oFFs chunk is supported as well as when pCAL is.
Changed type of proflen from png_int_32 to png_uint_32 in png_get_iCCP().
Version 1.0.5l [January 1, 2000]
Added functions png_set_read_user_chunk_fn() and png_get_user_chunk_ptr()
for setting a callback function to handle unknown chunks and for
retrieving the associated user pointer (Glenn).
Version 1.0.5m [January 7, 2000]
Added high-level functions png_read_png(), png_write_png(), png_free_pixels().
Version 1.0.5n [January 9, 2000]
Added png_free_PLTE() function, and modified png_set_PLTE() to malloc its
own memory for info_ptr->palette. This makes it safe for the calling
application to free its copy of the palette any time after it calls
png_set_PLTE().
Version 1.0.5o [January 20, 2000]
Cosmetic changes only (removed some trailing blanks and TABs)
Version 1.0.5p [January 31, 2000]
Renamed pngdll.mak to makefile.bd32
Cosmetic changes in pngtest.c
Version 1.0.5q [February 5, 2000]
Relocated the makefile.solaris warning about PATH problems.
Fixed pngvcrd.c bug by pushing/popping registers in mmxsupport (Bruce Oberg)
Revised makefile.gcmmx
Added PNG_SETJMP_SUPPORTED, PNG_SETJMP_NOT_SUPPORTED, and PNG_ABORT() macros
Version 1.0.5r [February 7, 2000]
Removed superfluous prototype for png_get_itxt from png.h
Fixed a bug in pngrtran.c that improperly expanded the background color.
Return *num_text=0 from png_get_text() when appropriate, and fix documentation
of png_get_text() in libpng.txt/libpng.3.
Version 1.0.5s [February 18, 2000]
Added "png_jmp_env()" macro to pngconf.h, to help people migrate to the
new error handler that's planned for the next libpng release, and changed
example.c, pngtest.c, and contrib programs to use this macro.
Revised some of the DLL-export macros in pngconf.h (Greg Roelofs)
Fixed a bug in png_read_png() that caused it to fail to expand some images
that it should have expanded.
Fixed some mistakes in the unused and undocumented INCH_CONVERSIONS functions
in pngget.c
Changed the allocation of palette, history, and trans arrays back to
the version 1.0.5 method (linking instead of copying) which restores
backward compatibility with version 1.0.5. Added some remarks about
that in example.c. Added "free_me" member to info_ptr and png_ptr
and added png_free_data() function.
Updated makefile.linux and makefile.gccmmx to make directories conditionally.
Made cosmetic changes to pngasmrd.h
Added png_set_rows() and png_get_rows(), for use with png_read|write_png().
Modified png_read_png() to allocate info_ptr->row_pointers only if it
hasn't already been allocated.
Version 1.0.5t [March 4, 2000]
Changed png_jmp_env() migration aiding macro to png_jmpbuf().
Fixed "interlace" typo (should be "interlaced") in contrib/gregbook/read2-x.c
Fixed bug with use of PNG_BEFORE_IHDR bit in png_ptr->mode, introduced when
PNG_FLAG_HAVE_CHUNK_HEADER was moved into png_ptr->mode in version 1.0.5b
Files in contrib/gregbook were revised to use png_jmpbuf() and to select
a 24-bit visual if one is available, and to allow abbreviated options.
Files in contrib/pngminus were revised to use the png_jmpbuf() macro.
Removed spaces in makefile.linux and makefile.gcmmx, introduced in 1.0.5s
Version 1.0.5u [March 5, 2000]
Simplified the code that detects old png.h in png.c and pngtest.c
Renamed png_spalette (_p, _pp) to png_sPLT_t (_tp, _tpp)
Increased precision of rgb_to_gray calculations from 8 to 15 bits and
added png_set_rgb_to_gray_fixed() function.
Added makefile.bc32 (32-bit Borland C++, C mode)
Version 1.0.5v [March 11, 2000]
Added some parentheses to the png_jmpbuf macro definition.
Updated references to the zlib home page, which has moved to freesoftware.com.
Corrected bugs in documentation regarding png_read_row() and png_write_row().
Updated documentation of png_rgb_to_gray calculations in libpng.3/libpng.txt.
Renamed makefile.borland,turboc3 back to makefile.bor,tc3 as in version 1.0.3,
revised borland makefiles; added makefile.ibmvac3 and makefile.gcc (Cosmin)
Version 1.0.6 [March 20, 2000]
Minor revisions of makefile.bor, libpng.txt, and gregbook/rpng2-win.c
Added makefile.sggcc (SGI IRIX with gcc)
Version 1.0.6d [April 7, 2000]
Changed sprintf() to strcpy() in png_write_sCAL_s() to work without STDIO
Added data_length parameter to png_decompress_chunk() function
Revised documentation to remove reference to abandoned png_free_chnk functions
Fixed an error in png_rgb_to_gray_fixed()
Revised example.c, usage of png_destroy_write_struct().
Renamed makefile.ibmvac3 to makefile.ibmc, added libpng.icc IBM project file
Added a check for info_ptr->free_me&PNG_FREE_TEXT when freeing text in png.c
Simplify png_sig_bytes() function to remove use of non-ISO-C strdup().
Version 1.0.6e [April 9, 2000]
Added png_data_freer() function.
In the code that checks for over-length tRNS chunks, added check of
info_ptr->num_trans as well as png_ptr->num_trans (Matthias Benckmann)
Minor revisions of libpng.txt/libpng.3.
Check for existing data and free it if the free_me flag is set, in png_set_*()
and png_handle_*().
Only define PNG_WEIGHTED_FILTERS_SUPPORTED when PNG_FLOATING_POINT_SUPPORTED
is defined.
Changed several instances of PNG_NO_CONSOLE_ID to PNG_NO_STDIO in pngrutil.c
and mentioned the purposes of the two macros in libpng.txt/libpng.3.
Version 1.0.6f [April 14, 2000]
Revised png_set_iCCP() and png_set_rows() to avoid prematurely freeing data.
Add checks in png_set_text() for NULL members of the input text structure.
Revised libpng.txt/libpng.3.
Removed superfluous prototype for png_set_iTXt from png.h
Removed "else" from pngread.c, after png_error(), and changed "0" to "length".
Changed several png_errors about malformed ancillary chunks to png_warnings.
Version 1.0.6g [April 24, 2000]
Added png_pass-* arrays to pnggccrd.c when PNG_USE_LOCAL_ARRAYS is defined.
Relocated paragraph about png_set_background() in libpng.3/libpng.txt
and other revisions (Matthias Benckmann)
Relocated info_ptr->free_me, png_ptr->free_me, and other info_ptr and
png_ptr members to restore binary compatibility with libpng-1.0.5
(breaks compatibility with libpng-1.0.6).
Version 1.0.6h [April 24, 2000]
Changed shared library so-number pattern from 2.x.y.z to xy.z (this builds
libpng.so.10 & libpng.so.10.6h instead of libpng.so.2 & libpng.so.2.1.0.6h)
This is a temporary change for test purposes.
Version 1.0.6i [May 2, 2000]
Rearranged some members at the end of png_info and png_struct, to put
unknown_chunks_num and free_me within the original size of the png_structs
and free_me, png_read_user_fn, and png_free_fn within the original png_info,
because some old applications allocate the structs directly instead of
using png_create_*().
Added documentation of user memory functions in libpng.txt/libpng.3
Modified png_read_png so that it will use user_allocated row_pointers
if present, unless free_me directs that it be freed, and added description
of the use of png_set_rows() and png_get_rows() in libpng.txt/libpng.3.
Added PNG_LEGACY_SUPPORTED macro, and #ifdef out all new (since version
1.00) members of png_struct and png_info, to regain binary compatibility
when you define this macro. Capabilities lost in this event
are user transforms (new in version 1.0.0),the user transform pointer
(new in version 1.0.2), rgb_to_gray (new in 1.0.5), iCCP, sCAL, sPLT,
the high-level interface, and unknown chunks support (all new in 1.0.6).
This was necessary because of old applications that allocate the structs
directly as authors were instructed to do in libpng-0.88 and earlier,
instead of using png_create_*().
Added modes PNG_CREATED_READ_STRUCT and PNG_CREATED_WRITE_STRUCT which
can be used to detect codes that directly allocate the structs, and
code to check these modes in png_read_init() and png_write_init() and
generate a libpng error if the modes aren't set and PNG_LEGACY_SUPPORTED
was not defined.
Added makefile.intel and updated makefile.watcom (Pawel Mrochen)
Version 1.0.6j [May 3, 2000]
Overloaded png_read_init() and png_write_init() with macros that convert
calls to png_read_init_2() or png_write_init_2() that check the version
and structure sizes.
Version 1.0.7beta11 [May 7, 2000]
Removed the new PNG_CREATED_READ_STRUCT and PNG_CREATED_WRITE_STRUCT modes
which are no longer used.
Eliminated the three new members of png_text when PNG_LEGACY_SUPPORTED is
defined or when neither PNG_READ_iTXt_SUPPORTED nor PNG_WRITE_iTXT_SUPPORTED
is defined.
Made PNG_NO_READ|WRITE_iTXt the default setting, to avoid memory
overrun when old applications fill the info_ptr->text structure directly.
Added PNGAPI macro, and added it to the definitions of all exported functions.
Relocated version macro definitions ahead of the includes of zlib.h and
pngconf.h in png.h.
Version 1.0.7beta12 [May 12, 2000]
Revised pngset.c to avoid a problem with expanding the png_debug macro.
Deleted some extraneous defines from pngconf.h
Made PNG_NO_CONSOLE_IO the default condition when PNG_BUILD_DLL is defined.
Use MSC _RPTn debugging instead of fprintf if _MSC_VER is defined.
Added png_access_version_number() function.
Check for mask&PNG_FREE_CHNK (for TEXT, SCAL, PCAL) in png_free_data().
Expanded libpng.3/libpng.txt information about png_data_freer().
Version 1.0.7beta14 [May 17, 2000] (beta13 was not published)
Changed pnggccrd.c and pngvcrd.c to handle bad adaptive filter types as
warnings instead of errors, as pngrutil.c does.
Set the PNG_INFO_IDAT valid flag in png_set_rows() so png_write_png()
will actually write IDATs.
Made the default PNG_USE_LOCAL_ARRAYS depend on PNG_DLL instead of WIN32.
Make png_free_data() ignore its final parameter except when freeing data
that can have multiple instances (text, sPLT, unknowns).
Fixed a new bug in png_set_rows().
Removed info_ptr->valid tests from png_free_data(), as in version 1.0.5.
Added png_set_invalid() function.
Fixed incorrect illustrations of png_destroy_write_struct() in example.c.
Version 1.0.7beta15 [May 30, 2000]
Revised the deliberately erroneous Linux setjmp code in pngconf.h to produce
fewer error messages.
Rearranged checks for Z_OK to check the most likely path first in pngpread.c
and pngwutil.c.
Added checks in pngtest.c for png_create_*() returning NULL, and mentioned
in libpng.txt/libpng.3 the need for applications to check this.
Changed names of png_default_*() functions in pngtest to pngtest_*().
Changed return type of png_get_x|y_offset_*() from png_uint_32 to png_int_32.
Fixed some bugs in the unused PNG_INCH_CONVERSIONS functions in pngget.c
Set each pointer to NULL after freeing it in png_free_data().
Worked around a problem in pngconf.h; AIX's strings.h defines an "index"
macro that conflicts with libpng's png_color_16.index. (Dimitri
Papadapoulos)
Added "msvc" directory with MSVC++ project files (Simon-Pierre Cadieux).
Version 1.0.7beta16 [June 4, 2000]
Revised the workaround of AIX string.h "index" bug.
Added a check for overlength PLTE chunk in pngrutil.c.
Added PNG_NO_POINTER_INDEXING macro to use array-indexing instead of pointer
indexing in pngrutil.c and pngwutil.c to accommodate a buggy compiler.
Added a warning in png_decompress_chunk() when it runs out of data, e.g.
when it tries to read an erroneous PhotoShop iCCP chunk.
Added PNG_USE_DLL macro.
Revised the copyright/disclaimer/license notice.
Added contrib/msvctest directory
Version 1.0.7rc1 [June 9, 2000]
Corrected the definition of PNG_TRANSFORM_INVERT_ALPHA (0x0400 not 0x0200)
Added contrib/visupng directory (Willem van Schaik)
Version 1.0.7beta18 [June 23, 2000]
Revised PNGAPI definition, and pngvcrd.c to work with __GCC__
and do not redefine PNGAPI if it is passed in via a compiler directive.
Revised visupng/PngFile.c to remove returns from within the Try block.
Removed leading underscores from "_PNG_H" and "_PNG_SAVE_BSD_SOURCE" macros.
Updated contrib/visupng/cexcept.h to version 1.0.0.
Fixed bugs in pngwrite.c and pngwutil.c that prevented writing iCCP chunks.
Version 1.0.7rc2 [June 28, 2000]
Updated license to include disclaimers required by UCITA.
Fixed "DJBPP" typo in pnggccrd.c introduced in beta18.
Version 1.0.7 [July 1, 2000]
Revised the definition of "trans_values" in libpng.3/libpng.txt
Version 1.0.8beta1 [July 8, 2000]
Added png_free(png_ptr, key) two places in pngpread.c to stop memory leaks.
Changed PNG_NO_STDIO to PNG_NO_CONSOLE_IO, several places in pngrutil.c and
pngwutil.c.
Changed PNG_EXPORT_VAR to use PNG_IMPEXP, in pngconf.h.
Removed unused "#include <assert.h>" from png.c
Added WindowsCE support.
Revised pnggccrd.c to work with gcc-2.95.2 and in the Cygwin environment.
Version 1.0.8beta2 [July 10, 2000]
Added project files to the wince directory and made further revisions
of pngtest.c, pngrio.c, and pngwio.c in support of WindowsCE.
Version 1.0.8beta3 [July 11, 2000]
Only set the PNG_FLAG_FREE_TRNS or PNG_FREE_TRNS flag in png_handle_tRNS()
for indexed-color input files to avoid potential double-freeing trans array
under some unusual conditions; problem was introduced in version 1.0.6f.
Further revisions to pngtest.c and files in the wince subdirectory.
Version 1.0.8beta4 [July 14, 2000]
Added the files pngbar.png and pngbar.jpg to the distribution.
Added makefile.cygwin, and cygwin support in pngconf.h
Added PNG_NO_ZALLOC_ZERO macro (makes png_zalloc skip zeroing memory)
Version 1.0.8rc1 [July 16, 2000]
Revised png_debug() macros and statements to eliminate compiler warnings.
Version 1.0.8 [July 24, 2000]
Added png_flush() in pngwrite.c, after png_write_IEND().
Updated makefile.hpux to build a shared library.
Version 1.0.9beta1 [November 10, 2000]
Fixed typo in scripts/makefile.hpux
Updated makevms.com in scripts and contrib/* and contrib/* (Martin Zinser)
Fixed seqence-point bug in contrib/pngminus/png2pnm (Martin Zinser)
Changed "cdrom.com" in documentation to "libpng.org"
Revised pnggccrd.c to get it all working, and updated makefile.gcmmx (Greg).
Changed type of "params" from voidp to png_voidp in png_read|write_png().
Make sure PNGAPI and PNG_IMPEXP are defined in pngconf.h.
Revised the 3 instances of WRITEFILE in pngtest.c.
Relocated "msvc" and "wince" project subdirectories into "dll" subdirectory.
Updated png.rc in dll/msvc project
Revised makefile.dec to define and use LIBPATH and INCPATH
Increased size of global png_libpng_ver[] array from 12 to 18 chars.
Made global png_libpng_ver[], png_sig[] and png_pass_*[] arrays const.
Removed duplicate png_crc_finish() from png_handle_bKGD() function.
Added a warning when application calls png_read_update_info() multiple times.
Revised makefile.cygwin
Fixed bugs in iCCP support in pngrutil.c and pngwutil.c.
Replaced png_set_empty_plte_permitted() with png_permit_mng_features().
Version 1.0.9beta2 [November 19, 2000]
Renamed the "dll" subdirectory "projects".
Added borland project files to "projects" subdirectory.
Set VS_FF_PRERELEASE and VS_FF_PATCHED flags in msvc/png.rc when appropriate.
Add error message in png_set_compression_buffer_size() when malloc fails.
Version 1.0.9beta3 [November 23, 2000]
Revised PNG_LIBPNG_BUILD_TYPE macro in png.h, used in the msvc project.
Removed the png_flush() in pngwrite.c that crashes some applications
that don't set png_output_flush_fn.
Added makefile.macosx and makefile.aix to scripts directory.
Version 1.0.9beta4 [December 1, 2000]
Change png_chunk_warning to png_warning in png_check_keyword().
Increased the first part of msg buffer from 16 to 18 in png_chunk_error().
Version 1.0.9beta5 [December 15, 2000]
Added support for filter method 64 (for PNG datastreams embedded in MNG).
Version 1.0.9beta6 [December 18, 2000]
Revised png_set_filter() to accept filter method 64 when appropriate.
Added new PNG_HAVE_PNG_SIGNATURE bit to png_ptr->mode and use it to
help prevent applications from using MNG features in PNG datastreams.
Added png_permit_mng_features() function.
Revised libpng.3/libpng.txt. Changed "filter type" to "filter method".
Version 1.0.9rc1 [December 23, 2000]
Revised test for PNG_HAVE_PNG_SIGNATURE in pngrutil.c
Fixed error handling of unknown compression type in png_decompress_chunk().
In pngconf.h, define __cdecl when _MSC_VER is defined.
Version 1.0.9beta7 [December 28, 2000]
Changed PNG_TEXT_COMPRESSION_zTXt to PNG_COMPRESSION_TYPE_BASE several places.
Revised memory management in png_set_hIST and png_handle_hIST in a backward
compatible manner. PLTE and tRNS were revised similarly.
Revised the iCCP chunk reader to ignore trailing garbage.
Version 1.0.9beta8 [January 12, 2001]
Moved pngasmrd.h into pngconf.h.
Improved handling of out-of-spec garbage iCCP chunks generated by PhotoShop.
Version 1.0.9beta9 [January 15, 2001]
Added png_set_invalid, png_permit_mng_features, and png_mmx_supported to
wince and msvc project module definition files.
Minor revision of makefile.cygwin.
Fixed bug with progressive reading of narrow interlaced images in pngpread.c
Version 1.0.9beta10 [January 16, 2001]
Do not typedef png_FILE_p in pngconf.h when PNG_NO_STDIO is defined.
Fixed "png_mmx_supported" typo in project definition files.
Version 1.0.9beta11 [January 19, 2001]
Updated makefile.sgi to make shared library.
Removed png_mmx_support() function and disabled PNG_MNG_FEATURES_SUPPORTED
by default, for the benefit of DLL forward compatibility. These will
be re-enabled in version 1.2.0.
Version 1.0.9rc2 [January 22, 2001]
Revised cygwin support.
Version 1.0.9 [January 31, 2001]
Added check of cygwin's ALL_STATIC in pngconf.h
Added "-nommx" parameter to contrib/gregbook/rpng2-win and rpng2-x demos.
Version 1.0.10beta1 [March 14, 2001]
Revised makefile.dec, makefile.sgi, and makefile.sggcc; added makefile.hpgcc.
Reformatted libpng.3 to eliminate bad line breaks.
Added checks for _mmx_supported in the read_filter_row function of pnggccrd.c
Added prototype for png_mmx_support() near the top of pnggccrd.c
Moved some error checking from png_handle_IHDR to png_set_IHDR.
Added PNG_NO_READ_SUPPORTED and PNG_NO_WRITE_SUPPORTED macros.
Revised png_mmx_support() function in pnggccrd.c
Restored version 1.0.8 PNG_WRITE_EMPTY_PLTE_SUPPORTED behavior in pngwutil.c
Fixed memory leak in contrib/visupng/PngFile.c
Fixed bugs in png_combine_row() in pnggccrd.c and pngvcrd.c (C version)
Added warnings when retrieving or setting gamma=0.
Increased the first part of msg buffer from 16 to 18 in png_chunk_warning().
Version 1.0.10rc1 [March 23, 2001]
Changed all instances of memcpy, strcpy, and strlen to png_memcpy, png_strcpy,
and png_strlen.
Revised png_mmx_supported() function in pnggccrd.c to return proper value.
Fixed bug in progressive reading (pngpread.c) with small images (height < 8).
Version 1.0.10 [March 30, 2001]
Deleted extraneous space (introduced in 1.0.9) from line 42 of makefile.cygwin
Added beos project files (Chris Herborth)
Version 1.0.11beta1 [April 3, 2001]
Added type casts on several png_malloc() calls (Dimitri Papadapoulos).
Removed a no-longer needed AIX work-around from pngconf.h
Changed several "//" single-line comments to C-style in pnggccrd.c
Version 1.0.11beta2 [April 11, 2001]
Removed PNGAPI from several functions whose prototypes did not have PNGAPI.
Updated scripts/pngos2.def
Version 1.0.11beta3 [April 14, 2001]
Added checking the results of many instances of png_malloc() for NULL
Version 1.0.11beta4 [April 20, 2001]
Undid the changes from version 1.0.11beta3. Added a check for NULL return
from user's malloc_fn().
Removed some useless type casts of the NULL pointer.
Added makefile.netbsd
Version 1.0.11 [April 27, 2001]
Revised makefile.netbsd
Version 1.0.12beta1 [May 14, 2001]
Test for Windows platform in pngconf.h when including malloc.h (Emmanuel Blot)
Updated makefile.cygwin and handling of Cygwin's ALL_STATIC in pngconf.h
Added some never-to-be-executed code in pnggccrd.c to quiet compiler warnings.
Eliminated the png_error about apps using png_read|write_init(). Instead,
libpng will reallocate the png_struct and info_struct if they are too small.
This retains future binary compatibility for old applications written for
libpng-0.88 and earlier.
Version 1.2.0beta1 [May 6, 2001]
Bumped DLLNUM to 2.
Re-enabled PNG_MNG_FEATURES_SUPPORTED and enabled PNG_ASSEMBLER_CODE_SUPPORTED
by default.
Added runtime selection of MMX features.
Added png_set_strip_error_numbers function and related macros.
Version 1.2.0beta2 [May 7, 2001]
Finished merging 1.2.0beta1 with version 1.0.11
Added a check for attempts to read or write PLTE in grayscale PNG datastreams.
Version 1.2.0beta3 [May 17, 2001]
Enabled user memory function by default.
Modified png_create_struct so it passes user mem_ptr to user memory allocator.
Increased png_mng_features flag from png_byte to png_uint_32.
Bumped shared-library (so-number) and dll-number to 3.
Version 1.2.0beta4 [June 23, 2001]
Check for missing profile length field in iCCP chunk and free chunk_data
in case of truncated iCCP chunk.
Bumped shared-library number to 3 in makefile.sgi and makefile.sggcc
Bumped dll-number from 2 to 3 in makefile.cygwin
Revised contrib/gregbook/rpng*-x.c to avoid a memory leak and to exit cleanly
if user attempts to run it on an 8-bit display.
Updated contrib/gregbook
Use png_malloc instead of png_zalloc to allocate palette in pngset.c
Updated makefile.ibmc
Added some typecasts to eliminate gcc 3.0 warnings. Changed prototypes
of png_write_oFFS width and height from png_uint_32 to png_int_32.
Updated example.c
Revised prototypes for png_debug_malloc and png_debug_free in pngtest.c
Version 1.2.0beta5 [August 8, 2001]
Revised contrib/gregbook
Revised makefile.gcmmx
Revised pnggccrd.c to conditionally compile some thread-unsafe code only
when PNG_THREAD_UNSAFE_OK is defined.
Added tests to prevent pngwutil.c from writing a bKGD or tRNS chunk with
value exceeding 2^bit_depth-1
Revised makefile.sgi and makefile.sggcc
Replaced calls to fprintf(stderr,...) with png_warning() in pnggccrd.c
Removed restriction that do_invert_mono only operate on 1-bit opaque files
Version 1.2.0 [September 1, 2001]
Changed a png_warning() to png_debug() in pnggccrd.c
Fixed contrib/gregbook/rpng-x.c, rpng2-x.c to avoid crash with XFreeGC().
Version 1.2.1beta1 [October 19, 2001]
Revised makefile.std in contrib/pngminus
Include background_1 in png_struct regardless of gamma support.
Revised makefile.netbsd and makefile.macosx, added makefile.darwin.
Revised example.c to provide more details about using row_callback().
Version 1.2.1beta2 [October 25, 2001]
Added type cast to each NULL appearing in a function call, except for
WINCE functions.
Added makefile.so9.
Version 1.2.1beta3 [October 27, 2001]
Removed type casts from all NULLs.
Simplified png_create_struct_2().
Version 1.2.1beta4 [November 7, 2001]
Revised png_create_info_struct() and png_creat_struct_2().
Added error message if png_write_info() was omitted.
Type cast NULLs appearing in function calls when _NO_PROTO or
PNG_TYPECAST_NULL is defined.
Version 1.2.1rc1 [November 24, 2001]
Type cast NULLs appearing in function calls except when PNG_NO_TYPECAST_NULL
is defined.
Changed typecast of "size" argument to png_size_t in pngmem.c calls to
the user malloc_fn, to agree with the prototype in png.h
Added a pop/push operation to pnggccrd.c, to preserve Eflag (Maxim Sobolev)
Updated makefile.sgi to recognize LIBPATH and INCPATH.
Updated various makefiles so "make clean" does not remove previous major
version of the shared library.
Version 1.2.1rc2 [December 4, 2001]
Always allocate 256-entry internal palette, hist, and trans arrays, to
avoid out-of-bounds memory reference caused by invalid PNG datastreams.
Added a check for prefix_length > data_length in iCCP chunk handler.
Version 1.2.1 [December 7, 2001]
None.
Version 1.2.2beta1 [February 22, 2002]
Fixed a bug with reading the length of iCCP profiles (Larry Reeves).
Revised makefile.linux, makefile.gcmmx, and makefile.sgi to generate
libpng.a, libpng12.so (not libpng.so.3), and libpng12/png.h
Revised makefile.darwin to remove "-undefined suppress" option.
Added checks for gamma and chromaticity values over 21474.83, which exceed
the limit for PNG unsigned 32-bit integers when encoded.
Revised calls to png_create_read_struct() and png_create_write_struct()
for simpler debugging.
Revised png_zalloc() so zlib handles errors (uses PNG_FLAG_MALLOC_NULL_MEM_OK)
Version 1.2.2beta2 [February 23, 2002]
Check chunk_length and idat_size for invalid (over PNG_MAX_UINT) lengths.
Check for invalid image dimensions in png_get_IHDR.
Added missing "fi;" in the install target of the SGI makefiles.
Added install-static to all makefiles that make shared libraries.
Always do gamma compensation when image is partially transparent.
Version 1.2.2beta3 [March 7, 2002]
Compute background.gray and background_1.gray even when color_type is RGB
in case image gets reduced to gray later.
Modified shared-library makefiles to install pkgconfig/libpngNN.pc.
Export (with PNGAPI) png_zalloc, png_zfree, and png_handle_as_unknown
Removed unused png_write_destroy_info prototype from png.h
Eliminated incorrect use of width_mmx from pnggccrd.c in pixel_bytes == 8 case
Added install-shared target to all makefiles that make shared libraries.
Stopped a double free of palette, hist, and trans when not using free_me.
Added makefile.32sunu for Sun Ultra 32 and makefile.64sunu for Sun Ultra 64.
Version 1.2.2beta4 [March 8, 2002]
Compute background.gray and background_1.gray even when color_type is RGB
in case image gets reduced to gray later (Jason Summers).
Relocated a misplaced /bin/rm in the "install-shared" makefile targets
Added PNG_1_0_X macro which can be used to build a 1.0.x-compatible library.
Version 1.2.2beta5 [March 26, 2002]
Added missing PNGAPI to several function definitions.
Check for invalid bit_depth or color_type in png_get_IHDR(), and
check for missing PLTE or IHDR in png_push_read_chunk() (Matthias Clasen).
Revised iTXt support to accept NULL for lang and lang_key.
Compute gamma for color components of background even when color_type is gray.
Changed "()" to "{}" in scripts/libpng.pc.in.
Revised makefiles to put png.h and pngconf.h only in $prefix/include/libpngNN
Revised makefiles to make symlink to libpng.so.NN in addition to libpngNN.so
Version 1.2.2beta6 [March 31, 2002]
Version 1.0.13beta1 [March 31, 2002]
Prevent png_zalloc() from trying to memset memory that it failed to acquire.
Add typecasts of PNG_MAX_UINT in pngset_cHRM_fixed() (Matt Holgate).
Ensure that the right function (user or default) is used to free the
png_struct after an error in png_create_read_struct_2().
Version 1.2.2rc1 [April 7, 2002]
Version 1.0.13rc1 [April 7, 2002]
Save the ebx register in pnggccrd.c (Sami Farin)
Add "mem_ptr = png_ptr->mem_ptr" in png_destroy_write_struct() (Paul Gardner).
Updated makefiles to put headers in include/libpng and remove old include/*.h.
Version 1.2.2 [April 15, 2002]
Version 1.0.13 [April 15, 2002]
Revised description of png_set_filter() in libpng.3/libpng.txt.
Revised makefile.netbsd and added makefile.neNNbsd and makefile.freebsd
Version 1.0.13patch01 [April 17, 2002]
Version 1.2.2patch01 [April 17, 2002]
Changed ${PNGMAJ}.${PNGVER} bug to ${PNGVER} in makefile.sgi and
makefile.sggcc
Fixed VER -> PNGVER typo in makefile.macosx and added install-static to
install
Added install: target to makefile.32sunu and makefile.64sunu
Version 1.0.13patch03 [April 18, 2002]
Version 1.2.2patch03 [April 18, 2002]
Revised 15 makefiles to link libpng.a to libpngNN.a and the include libpng
subdirectory to libpngNN subdirectory without the full pathname.
Moved generation of libpng.pc from "install" to "all" in 15 makefiles.
Version 1.2.3rc1 [April 28, 2002]
Added install-man target to 15 makefiles (Dimitri Papadopolous-Orfanos).
Added $(DESTDIR) feature to 24 makefiles (Tim Mooney)
Fixed bug with $prefix, should be $(prefix) in makefile.hpux.
Updated cygwin-specific portion of pngconf.h and revised makefile.cygwin
Added a link from libpngNN.pc to libpng.pc in 15 makefiles.
Added links from include/libpngNN/*.h to include/*.h in 24 makefiles.
Revised makefile.darwin to make relative links without full pathname.
Added setjmp() at the end of png_create_*_struct_2() in case user forgets
to put one in their application.
Restored png_zalloc() and png_zfree() prototypes to version 1.2.1 and
removed them from module definition files.
Version 1.2.3rc2 [May 1, 2002]
Fixed bug in reporting number of channels in pngget.c and pngset.c,
that was introduced in version 1.2.2beta5.
Exported png_zalloc(), png_zfree(), png_default_read(), png_default_write(),
png_default_flush(), and png_push_fill_buffer() and included them in
module definition files.
Added "libpng.pc" dependency to the "install-shared" target in 15 makefiles.
Version 1.2.3rc3 [May 1, 2002]
Revised prototype for png_default_flush()
Remove old libpng.pc and libpngNN.pc before installing new ones.
Version 1.2.3rc4 [May 2, 2002]
Typos in *.def files (png_default_read|write -> png_default_read|write_data)
In makefiles, changed rm libpng.NN.pc to rm libpngNN.pc
Added libpng-config and libpngNN-config and modified makefiles to install
them.
Changed $(MANPATH) to $(DESTDIR)$(MANPATH) in makefiles
Added "Win32 DLL VB" configuration to projects/msvc/libpng.dsp
Version 1.2.3rc5 [May 11, 2002]
Changed "error" and "message" in prototypes to "error_message" and
"warning_message" to avoid namespace conflict.
Revised 15 makefiles to build libpng-config from libpng-config-*.in
Once more restored png_zalloc and png_zfree to regular nonexported form.
Restored png_default_read|write_data, png_default_flush, png_read_fill_buffer
to nonexported form, but with PNGAPI, and removed them from module def
files.
Version 1.2.3rc6 [May 14, 2002]
Removed "PNGAPI" from png_zalloc() and png_zfree() in png.c
Changed "Gz" to "Gd" in projects/msvc/libpng.dsp and zlib.dsp.
Removed leftover libpng-config "sed" script from four makefiles.
Revised libpng-config creating script in 16 makefiles.
Version 1.2.3 [May 22, 2002]
Revised libpng-config target in makefile.cygwin.
Removed description of png_set_mem_fn() from documentation.
Revised makefile.freebsd.
Minor cosmetic changes to 15 makefiles, e.g., $(DI) = $(DESTDIR)/$(INCDIR).
Revised projects/msvc/README.txt
Changed -lpng to -lpngNN in LDFLAGS in several makefiles.
Version 1.2.4beta1 [May 24, 2002]
Added libpng.pc and libpng-config to "all:" target in 16 makefiles.
Fixed bug in 16 makefiles: $(DESTDIR)/$(LIBPATH) to $(DESTDIR)$(LIBPATH)
Added missing "\" before closing double quote in makefile.gcmmx.
Plugged various memory leaks; added png_malloc_warn() and png_set_text_2()
functions.
Version 1.2.4beta2 [June 25, 2002]
Plugged memory leak of png_ptr->current_text (Matt Holgate).
Check for buffer overflow before reading CRC in pngpread.c (Warwick Allison)
Added -soname to the loader flags in makefile.dec, makefile.sgi, and
makefile.sggcc.
Added "test-installed" target to makefile.linux, makefile.gcmmx,
makefile.sgi, and makefile.sggcc.
Version 1.2.4beta3 [June 28, 2002]
Plugged memory leak of row_buf in pngtest.c when there is a png_error().
Detect buffer overflow in pngpread.c when IDAT is corrupted with extra data.
Added "test-installed" target to makefile.32sunu, makefile.64sunu,
makefile.beos, makefile.darwin, makefile.dec, makefile.macosx,
makefile.solaris, makefile.hpux, makefile.hpgcc, and makefile.so9.
Version 1.2.4rc1 and 1.0.14rc1 [July 2, 2002]
Added "test-installed" target to makefile.cygwin and makefile.sco.
Revised pnggccrd.c to be able to back out version 1.0.x via PNG_1_0_X macro.
Version 1.2.4 and 1.0.14 [July 8, 2002]
Changed png_warning() to png_error() when width is too large to process.
Version 1.2.4patch01 [July 20, 2002]
Revised makefile.cygwin to use DLL number 12 instead of 13.
Version 1.2.5beta1 [August 6, 2002]
Added code to contrib/gregbook/readpng2.c to ignore unused chunks.
Replaced toucan.png in contrib/gregbook (it has been corrupt since 1.0.11)
Removed some stray *.o files from contrib/gregbook.
Changed png_error() to png_warning() about "Too much data" in pngpread.c
and about "Extra compressed data" in pngrutil.c.
Prevent png_ptr->pass from exceeding 7 in png_push_finish_row().
Updated makefile.hpgcc
Updated png.c and pnggccrd.c handling of return from png_mmx_support()
Version 1.2.5beta2 [August 15, 2002]
Only issue png_warning() about "Too much data" in pngpread.c when avail_in
is nonzero.
Updated makefiles to install a separate libpng.so.3 with its own rpath.
Version 1.2.5rc1 and 1.0.15rc1 [August 24, 2002]
Revised makefiles to not remove previous minor versions of shared libraries.
Version 1.2.5rc2 and 1.0.15rc2 [September 16, 2002]
Revised 13 makefiles to remove "-lz" and "-L$(ZLIBLIB)", etc., from shared
library loader directive.
Added missing "$OBJSDLL" line to makefile.gcmmx.
Added missing "; fi" to makefile.32sunu.
Version 1.2.5rc3 and 1.0.15rc3 [September 18, 2002]
Revised libpng-config script.
Version 1.2.5 and 1.0.15 [October 3, 2002]
Revised makefile.macosx, makefile.darwin, makefile.hpgcc, and makefile.hpux,
and makefile.aix.
Relocated two misplaced PNGAPI lines in pngtest.c
Version 1.2.6beta1 [October 22, 2002]
Commented out warning about uninitialized mmx_support in pnggccrd.c.
Changed "IBMCPP__" flag to "__IBMCPP__" in pngconf.h.
Relocated two more misplaced PNGAPI lines in pngtest.c
Fixed memory overrun bug in png_do_read_filler() with 16-bit datastreams,
introduced in version 1.0.2.
Revised makefile.macosx, makefile.dec, makefile.aix, and makefile.32sunu.
Version 1.2.6beta2 [November 1, 2002]
Added libpng-config "--ldopts" output.
Added "AR=ar" and "ARFLAGS=rc" and changed "ar rc" to "$(AR) $(ARFLAGS)"
in makefiles.
Version 1.2.6beta3 [July 18, 2004]
Reverted makefile changes from version 1.2.6beta2 and some of the changes
from version 1.2.6beta1; these will be postponed until version 1.2.7.
Version 1.2.6 is going to be a simple bugfix release.
Changed the one instance of "ln -sf" to "ln -f -s" in each Sun makefile.
Fixed potential overrun in pngerror.c by using strncpy instead of memcpy.
Added "#!/bin/sh" at the top of configure, for recognition of the
'x' flag under Cygwin (Cosmin).
Optimized vacuous tests that silence compiler warnings, in png.c (Cosmin).
Added support for PNG_USER_CONFIG, in pngconf.h (Cosmin).
Fixed the special memory handler for Borland C under DOS, in pngmem.c
(Cosmin).
Removed some spurious assignments in pngrutil.c (Cosmin).
Replaced 65536 with 65536L, and 0xffff with 0xffffL, to silence warnings
on 16-bit platforms (Cosmin).
Enclosed shift op expressions in parentheses, to silence warnings (Cosmin).
Used proper type png_fixed_point, to avoid problems on 16-bit platforms,
in png_handle_sRGB() (Cosmin).
Added compression_type to png_struct, and optimized the window size
inside the deflate stream (Cosmin).
Fixed definition of isnonalpha(), in pngerror.c and pngrutil.c (Cosmin).
Fixed handling of unknown chunks that come after IDAT (Cosmin).
Allowed png_error() and png_warning() to work even if png_ptr == NULL
(Cosmin).
Replaced row_info->rowbytes with row_bytes in png_write_find_filter()
(Cosmin).
Fixed definition of PNG_LIBPNG_VER_DLLNUM (Simon-Pierre).
Used PNG_LIBPNG_VER and PNG_LIBPNG_VER_STRING instead of the hardcoded
values in png.c (Simon-Pierre, Cosmin).
Initialized png_libpng_ver[] with PNG_LIBPNG_VER_STRING (Simon-Pierre).
Replaced PNG_LIBPNG_VER_MAJOR with PNG_LIBPNG_VER_DLLNUM in png.rc
(Simon-Pierre).
Moved the definition of PNG_HEADER_VERSION_STRING near the definitions
of the other PNG_LIBPNG_VER_... symbols in png.h (Cosmin).
Relocated #ifndef PNGAPI guards in pngconf.h (Simon-Pierre, Cosmin).
Updated scripts/makefile.vc(a)win32 (Cosmin).
Updated the MSVC project (Simon-Pierre, Cosmin).
Updated the Borland C++ Builder project (Cosmin).
Avoided access to asm_flags in pngvcrd.c, if PNG_1_0_X is defined (Cosmin).
Commented out warning about uninitialized mmx_support in pngvcrd.c (Cosmin).
Removed scripts/makefile.bd32 and scripts/pngdef.pas (Cosmin).
Added extra guard around inclusion of Turbo C memory headers, in pngconf.h
(Cosmin).
Renamed projects/msvc/ to projects/visualc6/, and projects/borland/ to
projects/cbuilder5/ (Cosmin).
Moved projects/visualc6/png32ms.def to scripts/pngw32.def,
and projects/visualc6/png.rc to scripts/pngw32.rc (Cosmin).
Added projects/visualc6/pngtest.dsp; removed contrib/msvctest/ (Cosmin).
Changed line endings to DOS style in cbuilder5 and visualc6 files, even
in the tar.* distributions (Cosmin).
Updated contrib/visupng/VisualPng.dsp (Cosmin).
Updated contrib/visupng/cexcept.h to version 2.0.0 (Cosmin).
Added a separate distribution with "configure" and supporting files (Junichi).
Version 1.2.6beta4 [July 28, 2004]
Added user ability to change png_size_t via a PNG_SIZE_T macro.
Added png_sizeof() and png_convert_size() functions.
Added PNG_SIZE_MAX (maximum value of a png_size_t variable.
Added check in png_malloc_default() for (size_t)size != (png_uint_32)size
which would indicate an overflow.
Changed sPLT failure action from png_error to png_warning and abandon chunk.
Changed sCAL and iCCP failures from png_error to png_warning and abandon.
Added png_get_uint_31(png_ptr, buf) function.
Added PNG_UINT_32_MAX macro.
Renamed PNG_MAX_UINT to PNG_UINT_31_MAX.
Made png_zalloc() issue a png_warning and return NULL on potential
overflow.
Turn on PNG_NO_ZALLOC_ZERO by default in version 1.2.x
Revised "clobber list" in pnggccrd.c so it will compile under gcc-3.4.
Revised Borland portion of png_malloc() to return NULL or issue
png_error() according to setting of PNG_FLAG_MALLOC_NULL_MEM_OK.
Added PNG_NO_SEQUENTIAL_READ_SUPPORTED macro to conditionally remove
sequential read support.
Added some "#if PNG_WRITE_SUPPORTED" blocks.
Added #ifdef to remove some redundancy in png_malloc_default().
Use png_malloc instead of png_zalloc to allocate the pallete.
Version 1.0.16rc1 and 1.2.6rc1 [August 4, 2004]
Fixed buffer overflow vulnerability in png_handle_tRNS()
Fixed integer arithmetic overflow vulnerability in png_read_png().
Fixed some harmless bugs in png_handle_sBIT, etc, that would cause
duplicate chunk types to go undetected.
Fixed some timestamps in the -config version
Rearranged order of processing of color types in png_handle_tRNS().
Added ROWBYTES macro to calculate rowbytes without integer overflow.
Updated makefile.darwin and removed makefile.macosx from scripts directory.
Imposed default one million column, one-million row limits on the image
dimensions, and added png_set_user_limits() function to override them.
Revised use of PNG_SET_USER_LIMITS_SUPPORTED macro.
Fixed wrong cast of returns from png_get_user_width|height_max().
Changed some "keep the compiler happy" from empty statements to returns,
Revised libpng.txt to remove 1.2.x stuff from the 1.0.x distribution
Version 1.0.16rc2 and 1.2.6rc2 [August 7, 2004]
Revised makefile.darwin and makefile.solaris. Removed makefile.macosx.
Revised pngtest's png_debug_malloc() to use png_malloc() instead of
png_malloc_default() which is not supposed to be exported.
Fixed off-by-one error in one of the conversions to PNG_ROWBYTES() in
pngpread.c. Bug was introduced in 1.2.6rc1.
Fixed bug in RGB to RGBX transformation introduced in 1.2.6rc1.
Fixed old bug in RGB to Gray transformation.
Fixed problem with 64-bit compilers by casting arguments to abs()
to png_int_32.
Changed "ln -sf" to "ln -f -s" in three makefiles (solaris, sco, so9).
Changed "HANDLE_CHUNK_*" to "PNG_HANDLE_CHUNK_*" (Cosmin)
Added "-@/bin/rm -f $(DL)/$(LIBNAME).so.$(PNGMAJ)" to 15 *NIX makefiles.
Added code to update the row_info->colortype in png_do_read_filler() (MSB).
Version 1.0.16rc3 and 1.2.6rc3 [August 9, 2004]
Eliminated use of "abs()" in testing cHRM and gAMA values, to avoid
trouble with some 64-bit compilers. Created PNG_OUT_OF_RANGE() macro.
Revised documentation of png_set_keep_unknown_chunks().
Check handle_as_unknown status in pngpread.c, as in pngread.c previously.
Moved "PNG_HANDLE_CHUNK_*" macros out of PNG_INTERNAL section of png.h
Added "rim" definitions for CONST4 and CONST6 in pnggccrd.c
Version 1.0.16rc4 and 1.2.6rc4 [August 10, 2004]
Fixed mistake in pngtest.c introduced in 1.2.6rc2 (declaration of
"pinfo" was out of place).
Version 1.0.16rc5 and 1.2.6rc5 [August 10, 2004]
Moved "PNG_HANDLE_CHUNK_*" macros out of PNG_ASSEMBLER_CODE_SUPPORTED
section of png.h where they were inadvertently placed in version rc3.
Version 1.2.6 and 1.0.16 [August 15, 2004]
Revised pngtest so memory allocation testing is only done when PNG_DEBUG==1.
Version 1.2.7beta1 [August 26, 2004]
Removed unused pngasmrd.h file.
Removed references to uu.net for archived files. Added references to
PNG Spec (second edition) and the PNG ISO/IEC Standard.
Added "test-dd" target in 15 makefiles, to run pngtest in DESTDIR.
Fixed bug with "optimized window size" in the IDAT datastream, that
causes libpng to write PNG files with incorrect zlib header bytes.
Version 1.2.7beta2 [August 28, 2004]
Fixed bug with sCAL chunk and big-endian machines (David Munro).
Undid new code added in 1.2.6rc2 to update the color_type in
png_set_filler().
Added png_set_add_alpha() that updates color type.
Version 1.0.17rc1 and 1.2.7rc1 [September 4, 2004]
Revised png_set_strip_filler() to not remove alpha if color_type has alpha.
Version 1.2.7 and 1.0.17 [September 12, 2004]
Added makefile.hp64
Changed projects/msvc/png32ms.def to scripts/png32ms.def in makefile.cygwin
Version 1.2.8beta1 [November 1, 2004]
Fixed bug in png_text_compress() that would fail to complete a large block.
Fixed bug, introduced in libpng-1.2.7, that overruns a buffer during
strip alpha operation in png_do_strip_filler().
Added PNG_1_2_X definition in pngconf.h
Use #ifdef to comment out png_info_init in png.c and png_read_init in
pngread.c (as of 1.3.0)
Version 1.2.8beta2 [November 2, 2004]
Reduce color_type to a nonalpha type after strip alpha operation in
png_do_strip_filler().
Version 1.2.8beta3 [November 3, 2004]
Revised definitions of PNG_MAX_UINT_32, PNG_MAX_SIZE, and PNG_MAXSUM
Version 1.2.8beta4 [November 12, 2004]
Fixed (again) definition of PNG_LIBPNG_VER_DLLNUM in png.h (Cosmin).
Added PNG_LIBPNG_BUILD_PRIVATE in png.h (Cosmin).
Set png_ptr->zstream.data_type to Z_BINARY, to avoid unnecessary detection
of data type in deflate (Cosmin).
Deprecated but continue to support SPECIALBUILD and PRIVATEBUILD in favor of
PNG_LIBPNG_BUILD_SPECIAL_STRING and PNG_LIBPNG_BUILD_PRIVATE_STRING.
Version 1.2.8beta5 [November 20, 2004]
Use png_ptr->flags instead of png_ptr->transformations to pass
PNG_STRIP_ALPHA info to png_do_strip_filler(), to preserve ABI
compatibility.
Revised handling of SPECIALBUILD, PRIVATEBUILD,
PNG_LIBPNG_BUILD_SPECIAL_STRING and PNG_LIBPNG_BUILD_PRIVATE_STRING.
Version 1.2.8rc1 [November 24, 2004]
Moved handling of BUILD macros from pngconf.h to png.h
Added definition of PNG_LIBPNG_BASE_TYPE in png.h, inadvertently
omitted from beta5.
Revised scripts/pngw32.rc
Despammed mailing addresses by masking "@" with "at".
Inadvertently installed a supposedly faster test version of pngrutil.c
Version 1.2.8rc2 [November 26, 2004]
Added two missing "\" in png.h
Change tests in pngread.c and pngpread.c to
if (png_ptr->transformations || (png_ptr->flags&PNG_FLAG_STRIP_ALPHA))
png_do_read_transformations(png_ptr);
Version 1.2.8rc3 [November 28, 2004]
Reverted pngrutil.c to version libpng-1.2.8beta5.
Added scripts/makefile.elf with supporting code in pngconf.h for symbol
versioning (John Bowler).
Version 1.2.8rc4 [November 29, 2004]
Added projects/visualc7 (Simon-pierre).
Version 1.2.8rc5 [November 29, 2004]
Fixed new typo in scripts/pngw32.rc
Version 1.2.8 [December 3, 2004]
Removed projects/visualc7, added projects/visualc71.
Version 1.2.9beta1 [February 21, 2006]
Initialized some structure members in pngwutil.c to avoid gcc-4.0.0 complaints
Revised man page and libpng.txt to make it clear that one should not call
png_read_end or png_write_end after png_read_png or png_write_png.
Updated references to png-mng-implement mailing list.
Fixed an incorrect typecast in pngrutil.c
Added PNG_NO_READ_SUPPORTED conditional for making a write-only library.
Added PNG_NO_WRITE_INTERLACING_SUPPORTED conditional.
Optimized alpha-inversion loops in pngwtran.c
Moved test for nonzero gamma outside of png_build_gamma_table() in pngrtran.c
Make sure num_trans is <= 256 before copying data in png_set_tRNS().
Make sure num_palette is <= 256 before copying data in png_set_PLTE().
Interchanged order of write_swap_alpha and write_invert_alpha transforms.
Added parentheses in the definition of PNG_LIBPNG_BUILD_TYPE (Cosmin).
Optimized zlib window flag (CINFO) in contrib/pngsuite/*.png (Cosmin).
Updated scripts/makefile.bc32 for Borland C++ 5.6 (Cosmin).
Exported png_get_uint_32, png_save_uint_32, png_get_uint_16, png_save_uint_16,
png_get_int_32, png_save_int_32, png_get_uint_31 (Cosmin).
Added type cast (png_byte) in png_write_sCAL() (Cosmin).
Fixed scripts/makefile.cygwin (Christian Biesinger, Cosmin).
Default iTXt support was inadvertently enabled.
Version 1.2.9beta2 [February 21, 2006]
Check for png_rgb_to_gray and png_gray_to_rgb read transformations before
checking for png_read_dither in pngrtran.c
Revised checking of chromaticity limits to accommodate extended RGB
colorspace (John Denker).
Changed line endings in some of the project files to CRLF, even in the
"Unix" tar distributions (Cosmin).
Made png_get_int_32 and png_save_int_32 always available (Cosmin).
Updated scripts/pngos2.def, scripts/pngw32.def and projects/wince/png32ce.def
with the newly exported functions.
Eliminated distributions without the "configure" script.
Updated INSTALL instructions.
Version 1.2.9beta3 [February 24, 2006]
Fixed CRCRLF line endings in contrib/visupng/VisualPng.dsp
Made libpng.pc respect EXEC_PREFIX (D. P. Kreil, J. Bowler)
Removed reference to pngasmrd.h from Makefile.am
Renamed CHANGES to ChangeLog.
Renamed LICENSE to COPYING.
Renamed ANNOUNCE to NEWS.
Created AUTHORS file.
Version 1.2.9beta4 [March 3, 2006]
Changed definition of PKGCONFIG from $prefix/lib to $libdir in configure.ac
Reverted to filenames LICENSE and ANNOUNCE; removed AUTHORS and COPYING.
Removed newline from the end of some error and warning messages.
Removed test for sqrt() from configure.ac and configure.
Made swap tables in pngtrans.c PNG_CONST (Carlo Bramix).
Disabled default iTXt support that was inadvertently enabled in
libpng-1.2.9beta1.
Added "OS2" to list of systems that don't need underscores, in pnggccrd.c
Removed libpng version and date from *.c files.
Version 1.2.9beta5 [March 4, 2006]
Removed trailing blanks from source files.
Put version and date of latest change in each source file, and changed
copyright year accordingly.
More cleanup of configure.ac, Makefile.am, and associated scripts.
Restored scripts/makefile.elf which was inadvertently deleted.
Version 1.2.9beta6 [March 6, 2006]
Fixed typo (RELEASE) in configuration files.
Version 1.2.9beta7 [March 7, 2006]
Removed libpng.vers and libpng.sym from libpng12_la_SOURCES in Makefile.am
Fixed inconsistent #ifdef's around png_sig_bytes() and png_set_sCAL_s()
in png.h.
Updated makefile.elf as suggested by debian.
Made cosmetic changes to some makefiles, adding LN_SF and other macros.
Made some makefiles accept "exec_prefix".
Version 1.2.9beta8 [March 9, 2006]
Fixed some "#if defined (..." which should be "#if defined(..."
Bug introduced in libpng-1.2.8.
Fixed inconsistency in definition of png_default_read_data()
Restored blank that was lost from makefile.sggcc "clean" target in beta7.
Revised calculation of "current" and "major" for irix in ltmain.sh
Changed "mkdir" to "MKDIR_P" in some makefiles.
Separated PNG_EXPAND and PNG_EXPAND_tRNS.
Added png_set_expand_gray_1_2_4_to_8() and deprecated
png_set_gray_1_2_4_to_8() which also expands tRNS to alpha.
Version 1.2.9beta9 [March 10, 2006]
Include "config.h" in pngconf.h when available.
Added some checks for NULL png_ptr or NULL info_ptr (timeless)
Version 1.2.9beta10 [March 20, 2006]
Removed extra CR from contrib/visualpng/VisualPng.dsw (Cosmin)
Made pnggccrd.c PIC-compliant (Christian Aichinger).
Added makefile.mingw (Wolfgang Glas).
Revised pngconf.h MMX checking.
Version 1.2.9beta11 [March 22, 2006]
Fixed out-of-order declaration in pngwrite.c that was introduced in beta9
Simplified some makefiles by using LIBSO, LIBSOMAJ, and LIBSOVER macros.
Version 1.2.9rc1 [March 31, 2006]
Defined PNG_USER_PRIVATEBUILD when including "pngusr.h" (Cosmin).
Removed nonsensical assertion check from pngtest.c (Cosmin).
Version 1.2.9 [April 14, 2006]
Revised makefile.beos and added "none" selector in ltmain.sh
Version 1.2.10beta1 [April 15, 2006]
Renamed "config.h" to "png_conf.h" and revised Makefile.am to add
-DPNG_BUILDING_LIBPNG to compile directive, and modified pngconf.h
to include png_conf.h only when PNG_BUILDING_LIBPNG is defined.
Version 1.2.10beta2 [April 15, 2006]
Manually updated Makefile.in and configure. Changed png_conf.h.in
back to config.h.
Version 1.2.10beta3 [April 15, 2006]
Change png_conf.h back to config.h in pngconf.h.
Version 1.2.10beta4 [April 16, 2006]
Change PNG_BUILDING_LIBPNG to PNG_CONFIGURE_LIBPNG in config/Makefile*.
Version 1.2.10beta5 [April 16, 2006]
Added a configure check for compiling assembler code in pnggccrd.c
Version 1.2.10beta6 [April 17, 2006]
Revised the configure check for pnggccrd.c
Moved -DPNG_CONFIGURE_LIBPNG into @LIBPNG_DEFINES@
Added @LIBPNG_DEFINES@ to arguments when building libpng.sym
Version 1.2.10beta7 [April 18, 2006]
Change "exec_prefix=$prefix" to "exec_prefix=$(prefix)" in makefiles.
Version 1.2.10rc1 [April 19, 2006]
Ensure pngconf.h doesn't define both PNG_USE_PNGGCCRD and PNG_USE_PNGVCRD
Fixed "LN_FS" typo in makefile.sco and makefile.solaris.
Version 1.2.10rc2 [April 20, 2006]
Added a backslash between -DPNG_CONFIGURE_LIBPNG and -DPNG_NO_ASSEMBLER_CODE
in configure.ac and configure
Made the configure warning about versioned symbols less arrogant.
Version 1.2.10rc3 [April 21, 2006]
Added a note in libpng.txt that png_set_sig_bytes(8) can be used when
writing an embedded PNG without the 8-byte signature.
Revised makefiles and configure to avoid making links to libpng.so.*
Version 1.2.10 [April 23, 2006]
Reverted configure to "rc2" state.
Version 1.2.11beta1 [May 31, 2006]
scripts/libpng.pc.in contained "configure" style version info and would
not work with makefiles.
The shared-library makefiles were linking to libpng.so.0 instead of
libpng.so.3 compatibility as the library.
Version 1.2.11beta2 [June 2, 2006]
Increased sprintf buffer from 50 to 52 chars in pngrutil.c to avoid
buffer overflow.
Fixed bug in example.c (png_set_palette_rgb -> png_set_palette_to_rgb)
Version 1.2.11beta3 [June 5, 2006]
Prepended "#! /bin/sh" to ltmail.sh and contrib/pngminus/*.sh (Cosmin).
Removed the accidental leftover Makefile.in~ (Cosmin).
Avoided potential buffer overflow and optimized buffer in
png_write_sCAL(), png_write_sCAL_s() (Cosmin).
Removed the include directories and libraries from CFLAGS and LDFLAGS
in scripts/makefile.gcc (Nelson A. de Oliveira, Cosmin).
Version 1.2.11beta4 [June 6, 2006]
Allow zero-length IDAT chunks after the entire zlib datastream, but not
after another intervening chunk type.
Version 1.0.19rc1, 1.2.11rc1 [June 13, 2006]
Deleted extraneous square brackets from [config.h] in configure.ac
Version 1.0.19rc2, 1.2.11rc2 [June 14, 2006]
Added prototypes for PNG_INCH_CONVERSIONS functions to png.h
Revised INSTALL and autogen.sh
Fixed typo in several makefiles (-W1 should be -Wl)
Added typedef for png_int_32 and png_uint_32 on 64-bit systems.
Version 1.0.19rc3, 1.2.11rc3 [June 15, 2006]
Removed the new typedefs for 64-bit systems (delay until version 1.4.0)
Added one zero element to png_gamma_shift[] array in pngrtran.c to avoid
reading out of bounds.
Version 1.0.19rc4, 1.2.11rc4 [June 15, 2006]
Really removed the new typedefs for 64-bit systems.
Version 1.0.19rc5, 1.2.11rc5 [June 22, 2006]
Removed png_sig_bytes entry from scripts/pngw32.def
Version 1.0.19, 1.2.11 [June 26, 2006]
None.
Version 1.0.20, 1.2.12 [June 27, 2006]
Really increased sprintf buffer from 50 to 52 chars in pngrutil.c to avoid
buffer overflow.
Version 1.2.13beta1 [October 2, 2006]
Removed AC_FUNC_MALLOC from configure.ac
Work around Intel-Mac compiler bug by setting PNG_NO_MMX_CODE in pngconf.h
Change "logical" to "bitwise" throughout documentation.
Detect and fix attempt to write wrong iCCP profile length (CVE-2006-7244)
Version 1.0.21, 1.2.13 [November 14, 2006]
Fix potential buffer overflow in sPLT chunk handler.
Fix Makefile.am to not try to link to noexistent files.
Check all exported functions for NULL png_ptr.
Version 1.2.14beta1 [November 17, 2006]
Relocated three misplaced tests for NULL png_ptr.
Built Makefile.in with automake-1.9.6 instead of 1.9.2.
Build configure with autoconf-2.60 instead of 2.59
Version 1.2.14beta2 [November 17, 2006]
Added some typecasts in png_zalloc().
Version 1.2.14rc1 [November 20, 2006]
Changed "strtod" to "png_strtod" in pngrutil.c
Version 1.0.22, 1.2.14 [November 27, 2006]
Added missing "$(srcdir)" in Makefile.am and Makefile.in
Version 1.2.15beta1 [December 3, 2006]
Generated configure with autoconf-2.61 instead of 2.60
Revised configure.ac to update libpng.pc and libpng-config.
Version 1.2.15beta2 [December 3, 2006]
Always export MMX asm functions, just stubs if not building pnggccrd.c
Version 1.2.15beta3 [December 4, 2006]
Add "png_bytep" typecast to profile while calculating length in pngwutil.c
Version 1.2.15beta4 [December 7, 2006]
Added scripts/CMakeLists.txt
Changed PNG_NO_ASSEMBLER_CODE to PNG_NO_MMX_CODE in scripts, like 1.4.0beta
Version 1.2.15beta5 [December 7, 2006]
Changed some instances of PNG_ASSEMBLER_* to PNG_MMX_* in pnggccrd.c
Revised scripts/CMakeLists.txt
Version 1.2.15beta6 [December 13, 2006]
Revised scripts/CMakeLists.txt and configure.ac
Version 1.2.15rc1 [December 18, 2006]
Revised scripts/CMakeLists.txt
Version 1.2.15rc2 [December 21, 2006]
Added conditional #undef jmpbuf in pngtest.c to undo #define in AIX headers.
Added scripts/makefile.nommx
Version 1.2.15rc3 [December 25, 2006]
Fixed shared library numbering error that was introduced in 1.2.15beta6.
Version 1.2.15rc4 [December 27, 2006]
Fixed handling of rgb_to_gray when png_ptr->color.gray isn't set.
Version 1.2.15rc5 [December 31, 2006]
Revised handling of rgb_to_gray.
Version 1.2.15 [January 5, 2007]
Added some (unsigned long) typecasts in pngtest.c to avoid printing errors.
Version 1.2.16beta1 [January 6, 2007]
Fix bugs in makefile.nommx
Version 1.2.16beta2 [January 16, 2007]
Revised scripts/CMakeLists.txt
Version 1.2.16 [January 31, 2007]
No changes.
Version 1.2.17beta1 [March 6, 2007]
Revised scripts/CMakeLists.txt to install both shared and static libraries.
Deleted a redundant line from pngset.c.
Version 1.2.17beta2 [April 26, 2007]
Relocated misplaced test for png_ptr == NULL in pngpread.c
Change "==" to "&" for testing PNG_RGB_TO_GRAY_ERR & PNG_RGB_TO_GRAY_WARN
flags.
Changed remaining instances of PNG_ASSEMBLER_* to PNG_MMX_*
Added pngerror() when write_IHDR fails in deflateInit2().
Added "const" to some array declarations.
Mention examples of libpng usage in the libpng*.txt and libpng.3 documents.
Version 1.2.17rc1 [May 4, 2007]
No changes.
Version 1.2.17rc2 [May 8, 2007]
Moved several PNG_HAVE_* macros out of PNG_INTERNAL because applications
calling set_unknown_chunk_location() need them.
Changed transformation flag from PNG_EXPAND_tRNS to PNG_EXPAND in
png_set_expand_gray_1_2_4_to_8().
Added png_ptr->unknown_chunk to hold working unknown chunk data, so it
can be free'ed in case of error. Revised unknown chunk handling in
pngrutil.c and pngpread.c to use this structure.
Version 1.2.17rc3 [May 8, 2007]
Revised symbol-handling in configure script.
Version 1.2.17rc4 [May 10, 2007]
Revised unknown chunk handling to avoid storing unknown critical chunks.
Version 1.0.25 [May 15, 2007]
Version 1.2.17 [May 15, 2007]
Added "png_ptr->num_trans=0" before error return in png_handle_tRNS,
to eliminate a vulnerability (CVE-2007-2445, CERT VU#684664)
Version 1.0.26 [May 15, 2007]
Version 1.2.18 [May 15, 2007]
Reverted the libpng-1.2.17rc3 change to symbol-handling in configure script
Version 1.2.19beta1 [May 18, 2007]
Changed "const static" to "static PNG_CONST" everywhere, mostly undoing
change of libpng-1.2.17beta2. Changed other "const" to "PNG_CONST"
Changed some handling of unused parameters, to avoid compiler warnings.
"if (unused == NULL) return;" becomes "unused = unused".
Version 1.2.19beta2 [May 18, 2007]
Only use the valid bits of tRNS value in png_do_expand() (Brian Cartier)
Version 1.2.19beta3 [May 19, 2007]
Add some "png_byte" typecasts in png_check_keyword() and write new_key
instead of key in zTXt chunk (Kevin Ryde).
Version 1.2.19beta4 [May 21, 2007]
Add png_snprintf() function and use it in place of sprint() for improved
defense against buffer overflows.
Version 1.2.19beta5 [May 21, 2007]
Fixed png_handle_tRNS() to only use the valid bits of tRNS value.
Changed handling of more unused parameters, to avoid compiler warnings.
Removed some PNG_CONST in pngwutil.c to avoid compiler warnings.
Version 1.2.19beta6 [May 22, 2007]
Added some #ifdef PNG_MMX_CODE_SUPPORTED where needed in pngvcrd.c
Added a special "_MSC_VER" case that defines png_snprintf to _snprintf
Version 1.2.19beta7 [May 22, 2007]
Squelched png_squelch_warnings() in pnggccrd.c and added
an #ifdef PNG_MMX_CODE_SUPPORTED block around the declarations that caused
the warnings that png_squelch_warnings was squelching.
Version 1.2.19beta8 [May 22, 2007]
Removed __MMX__ from test in pngconf.h.
Version 1.2.19beta9 [May 23, 2007]
Made png_squelch_warnings() available via PNG_SQUELCH_WARNINGS macro.
Revised png_squelch_warnings() so it might work.
Updated makefile.sgcc and makefile.solaris; added makefile.solaris-x86.
Version 1.2.19beta10 [May 24, 2007]
Resquelched png_squelch_warnings(), use "__attribute__((used))" instead.
Version 1.4.0beta1 [April 20, 2006]
Enabled iTXt support (changes png_struct, thus requires so-number change).
Cleaned up PNG_ASSEMBLER_CODE_SUPPORTED vs PNG_MMX_CODE_SUPPORTED
Eliminated PNG_1_0_X and PNG_1_2_X macros.
Removed deprecated functions png_read_init, png_write_init, png_info_init,
png_permit_empty_plte, png_set_gray_1_2_4_to_8, png_check_sig, and
removed the deprecated macro PNG_MAX_UINT.
Moved "PNG_INTERNAL" parts of png.h and pngconf.h into pngintrn.h
Removed many WIN32_WCE #ifdefs (Cosmin).
Reduced dependency on C-runtime library when on Windows (Simon-Pierre)
Replaced sprintf() with png_sprintf() (Simon-Pierre)
Version 1.4.0beta2 [April 20, 2006]
Revised makefiles and configure to avoid making links to libpng.so.*
Moved some leftover MMX-related defines from pngconf.h to pngintrn.h
Updated scripts/pngos2.def, pngw32.def, and projects/wince/png32ce.def
Version 1.4.0beta3 [May 10, 2006]
Updated scripts/pngw32.def to comment out MMX functions.
Added PNG_NO_GET_INT_32 and PNG_NO_SAVE_INT_32 macros.
Scripts/libpng.pc.in contained "configure" style version info and would
not work with makefiles.
Revised pngconf.h and added pngconf.h.in, so makefiles and configure can
pass defines to libpng and applications.
Version 1.4.0beta4 [May 11, 2006]
Revised configure.ac, Makefile.am, and many of the makefiles to write
their defines in pngconf.h.
Version 1.4.0beta5 [May 15, 2006]
Added a missing semicolon in Makefile.am and Makefile.in
Deleted extraneous square brackets from configure.ac
Version 1.4.0beta6 [June 2, 2006]
Increased sprintf buffer from 50 to 52 chars in pngrutil.c to avoid
buffer overflow.
Changed sonum from 0 to 1.
Removed unused prototype for png_check_sig() from png.h
Version 1.4.0beta7 [June 16, 2006]
Exported png_write_sig (Cosmin).
Optimized buffer in png_handle_cHRM() (Cosmin).
Set pHYs = 2835 x 2835 pixels per meter, and added
sCAL = 0.352778e-3 x 0.352778e-3 meters, in pngtest.png (Cosmin).
Added png_set_benign_errors(), png_benign_error(), png_chunk_benign_error().
Added typedef for png_int_32 and png_uint_32 on 64-bit systems.
Added "(unsigned long)" typecast on png_uint_32 variables in printf lists.
Version 1.4.0beta8 [June 22, 2006]
Added demonstration of user chunk support in pngtest.c, to support the
public sTER chunk and a private vpAg chunk.
Version 1.4.0beta9 [July 3, 2006]
Removed ordinals from scripts/pngw32.def and removed png_info_int and
png_set_gray_1_2_4_to_8 entries.
Inline call of png_get_uint_32() in png_get_uint_31().
Use png_get_uint_31() to get vpAg width and height in pngtest.c
Removed WINCE and Netware projects.
Removed standalone Y2KINFO file.
Version 1.4.0beta10 [July 12, 2006]
Eliminated automatic copy of pngconf.h to pngconf.h.in from configure and
some makefiles, because it was not working reliably. Instead, distribute
pngconf.h.in along with pngconf.h and cause configure and some of the
makefiles to update pngconf.h from pngconf.h.in.
Added pngconf.h to DEPENDENCIES in Makefile.am
Version 1.4.0beta11 [August 19, 2006]
Removed AC_FUNC_MALLOC from configure.ac.
Added a warning when writing iCCP profile with mismatched profile length.
Patched pnggccrd.c to assemble on x86_64 platforms.
Moved chunk header reading into a separate function png_read_chunk_header()
in pngrutil.c. The chunk header (len+sig) is now serialized in a single
operation (Cosmin).
Implemented support for I/O states. Added png_ptr member io_state, and
functions png_get_io_chunk_name() and png_get_io_state() in pngget.c
(Cosmin).
Added png_get_io_chunk_name and png_get_io_state to scripts/*.def (Cosmin).
Renamed scripts/pngw32.* to scripts/pngwin.* (Cosmin).
Removed the include directories and libraries from CFLAGS and LDFLAGS
in scripts/makefile.gcc (Cosmin).
Used png_save_uint_32() to set vpAg width and height in pngtest.c (Cosmin).
Cast to proper type when getting/setting vpAg units in pngtest.c (Cosmin).
Added pngintrn.h to the Visual C++ projects (Cosmin).
Removed scripts/list (Cosmin).
Updated copyright year in scripts/pngwin.def (Cosmin).
Removed PNG_TYPECAST_NULL and used standard NULL consistently (Cosmin).
Disallowed the user to redefine png_size_t, and enforced a consistent use
of png_size_t across libpng (Cosmin).
Changed the type of png_ptr->rowbytes, PNG_ROWBYTES() and friends
to png_size_t (Cosmin).
Removed png_convert_size() and replaced png_sizeof with sizeof (Cosmin).
Removed some unnecessary type casts (Cosmin).
Changed prototype of png_get_compression_buffer_size() and
png_set_compression_buffer_size() to work with png_size_t instead of
png_uint_32 (Cosmin).
Removed png_memcpy_check() and png_memset_check() (Cosmin).
Fixed a typo (png_byte --> png_bytep) in libpng.3 and libpng.txt (Cosmin).
Clarified that png_zalloc() does not clear the allocated memory,
and png_zalloc() and png_zfree() cannot be PNGAPI (Cosmin).
Renamed png_mem_size_t to png_alloc_size_t, fixed its definition in
pngconf.h, and used it in all memory allocation functions (Cosmin).
Renamed pngintrn.h to pngpriv.h, added a comment at the top of the file
mentioning that the symbols declared in that file are private, and
updated the scripts and the Visual C++ projects accordingly (Cosmin).
Removed circular references between pngconf.h and pngconf.h.in in
scripts/makefile.vc*win32 (Cosmin).
Removing trailing '.' from the warning and error messages (Cosmin).
Added pngdefs.h that is built by makefile or configure, instead of
pngconf.h.in (Glenn).
Detect and fix attempt to write wrong iCCP profile length.
Version 1.4.0beta12 [October 19, 2006]
Changed "logical" to "bitwise" in the documentation.
Work around Intel-Mac compiler bug by setting PNG_NO_MMX_CODE in pngconf.h
Add a typecast to stifle compiler warning in pngrutil.c
Version 1.4.0beta13 [November 10, 2006]
Fix potential buffer overflow in sPLT chunk handler.
Fix Makefile.am to not try to link to noexistent files.
Version 1.4.0beta14 [November 15, 2006]
Check all exported functions for NULL png_ptr.
Version 1.4.0beta15 [November 17, 2006]
Relocated two misplaced tests for NULL png_ptr.
Built Makefile.in with automake-1.9.6 instead of 1.9.2.
Build configure with autoconf-2.60 instead of 2.59
Add "install: all" in Makefile.am so "configure; make install" will work.
Version 1.4.0beta16 [November 17, 2006]
Added a typecast in png_zalloc().
Version 1.4.0beta17 [December 4, 2006]
Changed "new_key[79] = '\0';" to "(*new_key)[79] = '\0';" in pngwutil.c
Add "png_bytep" typecast to profile while calculating length in pngwutil.c
Version 1.4.0beta18 [December 7, 2006]
Added scripts/CMakeLists.txt
Version 1.4.0beta19 [May 16, 2007]
Revised scripts/CMakeLists.txt
Rebuilt configure and Makefile.in with newer tools.
Added conditional #undef jmpbuf in pngtest.c to undo #define in AIX headers.
Added scripts/makefile.nommx
Version 1.4.0beta20 [July 9, 2008]
Moved several PNG_HAVE_* macros from pngpriv.h to png.h because applications
calling set_unknown_chunk_location() need them.
Moved several macro definitions from pngpriv.h to pngconf.h
Merge with changes to the 1.2.X branch, as of 1.2.30beta04.
Deleted all use of the MMX assembler code and Intel-licensed optimizations.
Revised makefile.mingw
Version 1.4.0beta21 [July 21, 2008]
Moved local array "chunkdata" from pngrutil.c to the png_struct, so
it will be freed by png_read_destroy() in case of a read error (Kurt
Christensen).
Version 1.4.0beta22 [July 21, 2008]
Change "purpose" and "buffer" to png_ptr->chunkdata to avoid memory leaking.
Version 1.4.0beta23 [July 22, 2008]
Change "chunkdata = NULL" to "png_ptr->chunkdata = NULL" several places in
png_decompress_chunk().
Version 1.4.0beta24 [July 25, 2008]
Change all remaining "chunkdata" to "png_ptr->chunkdata" in
png_decompress_chunk(), and remove "chunkdata" from parameter list.
Put a call to png_check_chunk_name() in png_read_chunk_header().
Revised png_check_chunk_name() to reject a name with a lowercase 3rd byte.
Removed two calls to png_check_chunk_name() occuring later in the process.
Define PNG_NO_ERROR_NUMBERS by default in pngconf.h
Version 1.4.0beta25 [July 30, 2008]
Added a call to png_check_chunk_name() in pngpread.c
Reverted png_check_chunk_name() to accept a name with a lowercase 3rd byte.
Added png_push_have_buffer() function to pngpread.c
Eliminated PNG_BIG_ENDIAN_SUPPORTED and associated png_get_* macros.
Made inline expansion of png_get_*() optional with PNG_USE_READ_MACROS.
Eliminated all PNG_USELESS_TESTS and PNG_CORRECT_PALETTE_SUPPORTED code.
Synced contrib directory and configure files with libpng-1.2.30beta06.
Eliminated no-longer-used pngdefs.h (but it's still built in the makefiles)
Relocated a misplaced "#endif /* PNG_NO_WRITE_FILTER */" in pngwutil.c
Version 1.4.0beta26 [August 4, 2008]
Removed png_push_have_buffer() function in pngpread.c. It increased the
compiled library size slightly.
Changed "-Wall" to "-W -Wall" in the CFLAGS in all makefiles (Cosmin Truta)
Declared png_ptr "volatile" in pngread.c and pngwrite.c to avoid warnings.
Updated contrib/visupng/cexcept.h to version 2.0.1
Added PNG_LITERAL_CHARACTER macros for #, [, and ].
Version 1.4.0beta27 [August 5, 2008]
Revised usage of PNG_LITERAL_SHARP in pngerror.c.
Moved newline character from individual png_debug messages into the
png_debug macros.
Allow user to #define their own png_debug, png_debug1, and png_debug2.
Version 1.4.0beta28 [August 5, 2008]
Revised usage of PNG_LITERAL_SHARP in pngerror.c.
Added PNG_STRING_NEWLINE macro
Version 1.4.0beta29 [August 9, 2008]
Revised usage of PNG_STRING_NEWLINE to work on non-ISO compilers.
Added PNG_STRING_COPYRIGHT macro.
Added non-ISO versions of png_debug macros.
Version 1.4.0beta30 [August 14, 2008]
Added premultiplied alpha feature (Volker Wiendl).
Version 1.4.0beta31 [August 18, 2008]
Moved png_set_premultiply_alpha from pngtrans.c to pngrtran.c
Removed extra crc check at the end of png_handle_cHRM(). Bug introduced
in libpng-1.4.0beta20.
Version 1.4.0beta32 [August 19, 2008]
Added PNG_WRITE_FLUSH_SUPPORTED block around new png_flush() call.
Revised PNG_NO_STDIO version of png_write_flush()
Version 1.4.0beta33 [August 20, 2008]
Added png_get|set_chunk_cache_max() to limit the total number of sPLT,
text, and unknown chunks that can be stored.
Version 1.4.0beta34 [September 6, 2008]
Shortened tIME_string to 29 bytes in pngtest.c
Fixed off-by-one error introduced in png_push_read_zTXt() function in
libpng-1.2.30beta04/pngpread.c (Harald van Dijk)
Version 1.4.0beta35 [October 6, 2008]
Changed "trans_values" to "trans_color".
Changed so-number from 0 to 14. Some OS do not like 0.
Revised makefile.darwin to fix shared library numbering.
Change png_set_gray_1_2_4_to_8() to png_set_expand_gray_1_2_4_to_8()
in example.c (debian bug report)
Version 1.4.0beta36 [October 25, 2008]
Sync with tEXt vulnerability fix in libpng-1.2.33rc02.
Version 1.4.0beta37 [November 13, 2008]
Added png_check_cHRM in png.c and moved checking from pngget.c, pngrutil.c,
and pngwrite.c
Version 1.4.0beta38 [November 22, 2008]
Added check for zero-area RGB cHRM triangle in png_check_cHRM() and
png_check_cHRM_fixed().
Version 1.4.0beta39 [November 23, 2008]
Revised png_warning() to write its message on standard output by default
when warning_fn is NULL.
Version 1.4.0beta40 [November 24, 2008]
Eliminated png_check_cHRM(). Instead, always use png_check_cHRM_fixed().
In png_check_cHRM_fixed(), ensure white_y is > 0, and removed redundant
check for all-zero coordinates that is detected by the triangle check.
Version 1.4.0beta41 [November 26, 2008]
Fixed string vs pointer-to-string error in png_check_keyword().
Rearranged test expressions in png_check_cHRM_fixed() to avoid internal
overflows.
Added PNG_NO_CHECK_cHRM conditional.
Version 1.4.0beta42, 43 [December 1, 2008]
Merge png_debug with version 1.2.34beta04.
Version 1.4.0beta44 [December 6, 2008]
Removed redundant check for key==NULL before calling png_check_keyword()
to ensure that new_key gets initialized and removed extra warning
(Merge with version 1.2.34beta05 -- Arvan Pritchard).
Version 1.4.0beta45 [December 9, 2008]
In png_write_png(), respect the placement of the filler bytes in an earlier
call to png_set_filler() (Jim Barry).
Version 1.4.0beta46 [December 10, 2008]
Undid previous change and added PNG_TRANSFORM_STRIP_FILLER_BEFORE and
PNG_TRANSFORM_STRIP_FILLER_AFTER conditionals and deprecated
PNG_TRANSFORM_STRIP_FILLER (Jim Barry).
Version 1.4.0beta47 [December 15, 2008]
Support for dithering was disabled by default, because it has never
been well tested and doesn't work very well. The code has not
been removed, however, and can be enabled by building libpng with
PNG_READ_DITHER_SUPPORTED defined.
Version 1.4.0beta48 [February 14, 2009]
Added new exported function png_calloc().
Combined several instances of png_malloc(); png_memset() into png_calloc().
Removed prototype for png_freeptr() that was added in libpng-1.4.0beta24
but was never defined.
Version 1.4.0beta49 [February 28, 2009]
Added png_fileno() macro to pngconf.h, used in pngwio.c
Corrected order of #ifdef's in png_debug definition in png.h
Fixed bug introduced in libpng-1.4.0beta48 with the memset arguments
for pcal_params.
Fixed order of #ifdef directives in the png_debug defines in png.h
(bug introduced in libpng-1.2.34/1.4.0beta29).
Revised comments in png_set_read_fn() and png_set_write_fn().
Version 1.4.0beta50 [March 18, 2009]
Use png_calloc() instead of png_malloc() to allocate big_row_buf when
reading an interlaced file, to avoid a possible UMR.
Undid revision of PNG_NO_STDIO version of png_write_flush(). Users
having trouble with fflush() can build with PNG_NO_WRITE_FLUSH defined
or supply their own flush_fn() replacement.
Revised libpng*.txt and png.h documentation about use of png_write_flush()
and png_set_write_fn().
Removed fflush() from pngtest.c.
Added "#define PNG_NO_WRITE_FLUSH" to contrib/pngminim/encoder/pngusr.h
Version 1.4.0beta51 [March 21, 2009]
Removed new png_fileno() macro from pngconf.h .
Version 1.4.0beta52 [March 27, 2009]
Relocated png_do_chop() ahead of building gamma tables in pngrtran.c
This avoids building 16-bit gamma tables unnecessarily.
Removed fflush() from pngtest.c.
Added "#define PNG_NO_WRITE_FLUSH" to contrib/pngminim/encoder/pngusr.h
Added a section on differences between 1.0.x and 1.2.x to libpng.3/libpng.txt
Version 1.4.0beta53 [April 1, 2009]
Removed some remaining MMX macros from pngpriv.h
Fixed potential memory leak of "new_name" in png_write_iCCP() (Ralph Giles)
Version 1.4.0beta54 [April 13, 2009]
Added "ifndef PNG_SKIP_SETJMP_CHECK" block in pngconf.h to allow
application code writers to bypass the check for multiple inclusion
of setjmp.h when they know that it is safe to ignore the situation.
Eliminated internal use of setjmp() in pngread.c and pngwrite.c
Reordered ancillary chunks in pngtest.png to be the same as what
pngtest now produces, and made some cosmetic changes to pngtest output.
Eliminated deprecated png_read_init_3() and png_write_init_3() functions.
Version 1.4.0beta55 [April 15, 2009]
Simplified error handling in pngread.c and pngwrite.c by putting
the new png_read_cleanup() and png_write_cleanup() functions inline.
Version 1.4.0beta56 [April 25, 2009]
Renamed "user_chunk_data" to "my_user_chunk_data" in pngtest.c to suppress
"shadowed declaration" warning from gcc-4.3.3.
Renamed "gamma" to "png_gamma" in pngset.c to avoid "shadowed declaration"
warning about a global "gamma" variable in math.h on some platforms.
Version 1.4.0beta57 [May 2, 2009]
Removed prototype for png_freeptr() that was added in libpng-1.4.0beta24
but was never defined (again).
Rebuilt configure scripts with autoconf-2.63 instead of 2.62
Removed pngprefs.h and MMX from makefiles
Version 1.4.0beta58 [May 14, 2009]
Changed pngw32.def to pngwin.def in makefile.mingw (typo was introduced
in beta57).
Clarified usage of sig_bit versus sig_bit_p in example.c (Vincent Torri)
Version 1.4.0beta59 [May 15, 2009]
Reformated sources in libpng style (3-space intentation, comment format)
Fixed typo in libpng docs (PNG_FILTER_AVE should be PNG_FILTER_AVG)
Added sections about the git repository and our coding style to the
documentation
Relocated misplaced #endif in pngwrite.c, sCAL chunk handler.
Version 1.4.0beta60 [May 19, 2009]
Conditionally compile png_read_finish_row() which is not used by
progressive readers.
Added contrib/pngminim/preader to demonstrate building minimal progressive
decoder, based on contrib/gregbook with embedded libpng and zlib.
Version 1.4.0beta61 [May 20, 2009]
In contrib/pngminim/*, renamed "makefile.std" to "makefile", since there
is only one makefile in those directories, and revised the README files
accordingly.
More reformatting of comments, mostly to capitalize sentences.
Version 1.4.0beta62 [June 2, 2009]
Added "#define PNG_NO_WRITE_SWAP" to contrib/pngminim/encoder/pngusr.h
and "define PNG_NO_READ_SWAP" to decoder/pngusr.h and preader/pngusr.h
Reformatted several remaining "else statement" into two lines.
Added a section to the libpng documentation about using png_get_io_ptr()
in configure scripts to detect the presence of libpng.
Version 1.4.0beta63 [June 15, 2009]
Revised libpng*.txt and libpng.3 to mention calling png_set_IHDR()
multiple times and to specify the sample order in the tRNS chunk,
because the ISO PNG specification has a typo in the tRNS table.
Changed several PNG_UNKNOWN_CHUNK_SUPPORTED to
PNG_HANDLE_AS_UNKNOWN_SUPPORTED, to make the png_set_keep mechanism
available for ignoring known chunks even when not saving unknown chunks.
Adopted preference for consistent use of "#ifdef" and "#ifndef" versus
"#if defined()" and "if !defined()" where possible.
Version 1.4.0beta64 [June 24, 2009]
Eliminated PNG_LEGACY_SUPPORTED code.
Moved the various unknown chunk macro definitions outside of the
PNG_READ|WRITE_ANCILLARY_CHUNK_SUPPORTED blocks.
Version 1.4.0beta65 [June 26, 2009]
Added a reference to the libpng license in each file.
Version 1.4.0beta66 [June 27, 2009]
Refer to the libpng license instead of the libpng license in each file.
Version 1.4.0beta67 [July 6, 2009]
Relocated INVERT_ALPHA within png_read_png() and png_write_png().
Added high-level API transform PNG_TRANSFORM_GRAY_TO_RGB.
Added an "xcode" project to the projects directory (Alam Arias).
Version 1.4.0beta68 [July 19, 2009]
Avoid some tests in filter selection in pngwutil.c
Version 1.4.0beta69 [July 25, 2009]
Simplified the new filter-selection test. This runs faster in the
common "PNG_ALL_FILTERS" and PNG_FILTER_NONE cases.
Removed extraneous declaration from the new call to png_read_gray_to_rgb()
(bug introduced in libpng-1.4.0beta67).
Fixed up xcode project (Alam Arias)
Added a prototype for png_64bit_product() in png.c
Version 1.4.0beta70 [July 27, 2009]
Avoid a possible NULL dereference in debug build, in png_set_text_2().
(bug introduced in libpng-0.95, discovered by Evan Rouault)
Version 1.4.0beta71 [July 29, 2009]
Rebuilt configure scripts with autoconf-2.64.
Version 1.4.0beta72 [August 1, 2009]
Replaced *.tar.lzma with *.tar.xz in distribution. Get the xz codec
from <http://tukaani.org/xz>.
Version 1.4.0beta73 [August 1, 2009]
Reject attempt to write iCCP chunk with negative embedded profile length
(JD Chen) (CVE-2009-5063).
Version 1.4.0beta74 [August 8, 2009]
Changed png_ptr and info_ptr member "trans" to "trans_alpha".
Version 1.4.0beta75 [August 21, 2009]
Removed an extra png_debug() recently added to png_write_find_filter().
Fixed incorrect #ifdef in pngset.c regarding unknown chunk support.
Version 1.4.0beta76 [August 22, 2009]
Moved an incorrectly located test in png_read_row() in pngread.c
Version 1.4.0beta77 [August 27, 2009]
Removed lpXYZ.tar.bz2 (with CRLF), KNOWNBUG, libpng-x.y.z-KNOWNBUG.txt,
and the "noconfig" files from the distribution.
Moved CMakeLists.txt from scripts into the main libpng directory.
Various bugfixes and improvements to CMakeLists.txt (Philip Lowman)
Version 1.4.0beta78 [August 31, 2009]
Converted all PNG_NO_* tests to PNG_*_SUPPORTED everywhere except pngconf.h
Eliminated PNG_NO_FREE_ME and PNG_FREE_ME_SUPPORTED macros.
Use png_malloc plus a loop instead of png_calloc() to initialize
row_pointers in png_read_png().
Version 1.4.0beta79 [September 1, 2009]
Eliminated PNG_GLOBAL_ARRAYS and PNG_LOCAL_ARRAYS; always use local arrays.
Eliminated PNG_CALLOC_SUPPORTED macro and always provide png_calloc().
Version 1.4.0beta80 [September 17, 2009]
Removed scripts/libpng.icc
Changed typecast of filler from png_byte to png_uint_16 in png_set_filler().
(Dennis Gustafsson)
Fixed typo introduced in beta78 in pngtest.c ("#if def " should be "#ifdef ")
Version 1.4.0beta81 [September 23, 2009]
Eliminated unused PNG_FLAG_FREE_* defines from pngpriv.h
Expanded TAB characters in pngrtran.c
Removed PNG_CONST from all "PNG_CONST PNG_CHNK" declarations to avoid
compiler complaints about doubly declaring things "const".
Changed all "#if [!]defined(X)" to "if[n]def X" where possible.
Eliminated unused png_ptr->row_buf_size
Version 1.4.0beta82 [September 25, 2009]
Moved redundant IHDR checking into new png_check_IHDR() in png.c
and report all errors found in the IHDR data.
Eliminated useless call to png_check_cHRM() from pngset.c
Version 1.4.0beta83 [September 25, 2009]
Revised png_check_IHDR() to eliminate bogus complaint about filter_type.
Version 1.4.0beta84 [September 30, 2009]
Fixed some inconsistent indentation in pngconf.h
Revised png_check_IHDR() to add a test for width variable less than 32-bit.
Version 1.4.0beta85 [October 1, 2009]
Revised png_check_IHDR() again, to check info_ptr members instead of
the contents of the returned parameters.
Version 1.4.0beta86 [October 9, 2009]
Updated the "xcode" project (Alam Arias).
Eliminated a shadowed declaration of "pp" in png_handle_sPLT().
Version 1.4.0rc01 [October 19, 2009]
Trivial cosmetic changes.
Version 1.4.0beta87 [October 30, 2009]
Moved version 1.4.0 back into beta.
Version 1.4.0beta88 [October 30, 2009]
Revised libpng*.txt section about differences between 1.2.x and 1.4.0
because most of the new features have now been ported back to 1.2.41
Version 1.4.0beta89 [November 1, 2009]
More bugfixes and improvements to CMakeLists.txt (Philip Lowman)
Removed a harmless extra png_set_invert_alpha() from pngwrite.c
Apply png_user_chunk_cache_max within png_decompress_chunk().
Merged libpng-1.2.41.txt with libpng-1.4.0.txt where appropriate.
Version 1.4.0beta90 [November 2, 2009]
Removed all remaining WIN32_WCE #ifdefs except those involving the
time.h "tm" structure
Version 1.4.0beta91 [November 3, 2009]
Updated scripts/pngw32.def and projects/wince/png32ce.def
Copied projects/wince/png32ce.def to the scripts directory.
Added scripts/makefile.wce
Patched ltmain.sh for wince support.
Added PNG_CONVERT_tIME_SUPPORTED macro.
Version 1.4.0beta92 [November 4, 2009]
Make inclusion of time.h in pngconf.h depend on PNG_CONVERT_tIME_SUPPORTED
Make #define PNG_CONVERT_tIME_SUPPORTED depend on PNG_WRITE_tIME_SUPPORTED
Revised libpng*.txt to describe differences from 1.2.40 to 1.4.0 (instead
of differences from 1.2.41 to 1.4.0)
Version 1.4.0beta93 [November 7, 2009]
Added PNG_DEPSTRUCT, PNG_DEPRECATED, PNG_USE_RESULT, PNG_NORETURN, and
PNG_ALLOCATED macros to detect deprecated direct access to the
png_struct or info_struct members and other deprecated usage in
applications (John Bowler).
Updated scripts/makefile* to add "-DPNG_CONFIGURE_LIBPNG" to CFLAGS,
to prevent warnings about direct access to png structs by libpng
functions while building libpng. They need to be tested, especially
those using compilers other than gcc.
Updated projects/visualc6 and visualc71 with "/d PNG_CONFIGURE_LIBPNG".
They should work but still need to be updated to remove
references to pnggccrd.c or pngvcrd.c and ASM building.
Added README.txt to the beos, cbuilder5, netware, and xcode projects warning
that they need to be updated, to remove references to pnggccrd.c and
pngvcrd.c and to depend on pngpriv.h
Removed three direct references to read_info_ptr members in pngtest.c
that were detected by the new PNG_DEPSTRUCT macro.
Moved the png_debug macro definitions and the png_read_destroy(),
png_write_destroy() and png_far_to_near() prototypes from png.h
to pngpriv.h (John Bowler)
Moved the synopsis lines for png_read_destroy(), png_write_destroy()
png_debug(), png_debug1(), and png_debug2() from libpng.3 to libpngpf.3.
Version 1.4.0beta94 [November 9, 2009]
Removed the obsolete, unused pnggccrd.c and pngvcrd.c files.
Updated CMakeLists.txt to add "-DPNG_CONFIGURE_LIBPNG" to the definitions.
Removed dependency of pngtest.o on pngpriv.h in the makefiles.
Only #define PNG_DEPSTRUCT, etc. in pngconf.h if not already defined.
Version 1.4.0beta95 [November 10, 2009]
Changed png_check_sig() to !png_sig_cmp() in contrib programs.
Added -DPNG_CONFIGURE_LIBPNG to contrib/pngminm/*/makefile
Changed png_check_sig() to !png_sig_cmp() in contrib programs.
Corrected the png_get_IHDR() call in contrib/gregbook/readpng2.c
Changed pngminim/*/gather.sh to stop trying to remove pnggccrd.c and pngvcrd.c
Added dependency on pngpriv.h in contrib/pngminim/*/makefile
Version 1.4.0beta96 [November 12, 2009]
Renamed scripts/makefile.wce to scripts/makefile.cegcc
Revised Makefile.am to use libpng.sys while building libpng.so
so that only PNG_EXPORT functions are exported.
Removed the deprecated png_check_sig() function/macro.
Removed recently removed function names from scripts/*.def
Revised pngtest.png to put chunks in the same order written by pngtest
(evidently the same change made in libpng-1.0beta54 was lost).
Added PNG_PRIVATE macro definition in pngconf.h for possible future use.
Version 1.4.0beta97 [November 13, 2009]
Restored pngtest.png to the libpng-1.4.0beta7 version.
Removed projects/beos and netware.txt; no one seems to be supporting them.
Revised Makefile.in
Version 1.4.0beta98 [November 13, 2009]
Added the "xcode" project to zip distributions,
Fixed a typo in scripts/pngwin.def introduced in beta97.
Version 1.4.0beta99 [November 14, 2009]
Moved libpng-config.in and libpng.pc-configure.in out of the scripts
directory, to libpng-config.in and libpng-pc.in, respectively, and
modified Makefile.am and configure.ac accordingly. Now "configure"
needs nothing from the "scripts" directory.
Avoid redefining PNG_CONST in pngconf.h
Version 1.4.0beta100 [November 14, 2009]
Removed ASM builds from projects/visualc6 and projects/visualc71
Removed scripts/makefile.nommx and makefile.vcawin32
Revised CMakeLists.txt to account for new location of libpng-config.in
and libpng-pc.in
Updated INSTALL to reflect removal and relocation of files.
Version 1.4.0beta101 [November 14, 2009]
Restored the binary files (*.jpg, *.png, some project files) that were
accidentally deleted from the zip and 7z distributions when the xcode
project was added.
Version 1.4.0beta102 [November 18, 2009]
Added libpng-config.in and libpng-pc.in to the zip and 7z distributions.
Fixed a typo in projects/visualc6/pngtest.dsp, introduced in beta100.
Moved descriptions of makefiles and other scripts out of INSTALL into
scripts/README.txt
Updated the copyright year in scripts/pngwin.rc from 2006 to 2009.
Version 1.4.0beta103 [November 21, 2009]
Removed obsolete comments about ASM from projects/visualc71/README_zlib.txt
Align row_buf on 16-byte boundary in memory.
Restored the PNG_WRITE_FLUSH_AFTER_IEND_SUPPORTED guard around the call
to png_flush() after png_write_IEND(). See 1.4.0beta32, 1.4.0beta50
changes above and 1.2.30, 1.2.30rc01 and rc03 in 1.2.41 CHANGES. Someone
needs this feature.
Make the 'png_jmpbuf' macro expand to a call that records the correct
longjmp function as well as returning a pointer to the setjmp
jmp_buf buffer, and marked direct access to jmpbuf 'deprecated'.
(John Bowler)
Version 1.4.0beta104 [November 22, 2009]
Removed png_longjmp_ptr from scripts/*.def and libpng.3
Rebuilt configure scripts with autoconf-2.65
Version 1.4.0beta105 [November 25, 2009]
Use fast integer PNG_DIVIDE_BY_255() or PNG_DIVIDE_BY_65535()
to accomplish alpha premultiplication when
PNG_READ_COMPOSITE_NODIV_SUPPORTED is defined.
Changed "/255" to "/255.0" in background calculations to make it clear
that the 255 is used as a double.
Version 1.4.0beta106 [November 27, 2009]
Removed premultiplied alpha feature.
Version 1.4.0beta107 [December 4, 2009]
Updated README
Added "#define PNG_NO_PEDANTIC_WARNINGS" in the libpng source files.
Removed "-DPNG_CONFIGURE_LIBPNG" from the makefiles and projects.
Revised scripts/makefile.netbsd, makefile.openbsd, and makefile.sco
to put png.h and pngconf.h in $prefix/include, like the other scripts,
instead of in $prefix/include/libpng. Also revised makefile.sco
to put them in $prefix/include/libpng15 instead of in
$prefix/include/libpng/libpng15.
Version 1.4.0beta108 [December 11, 2009]
Removed leftover "-DPNG_CONFIGURE_LIBPNG" from contrib/pngminim/*/makefile
Relocated png_do_chop() to its original position in pngrtran.c; the
change in version 1.2.41beta08 caused transparency to be handled wrong
in some 16-bit datastreams (Yusaku Sugai).
Version 1.4.0beta109 [December 13, 2009]
Added "bit_depth" parameter to the private png_build_gamma_table() function.
Pass bit_depth=8 to png_build_gamma_table() when bit_depth is 16 but the
PNG_16_TO_8 transform has been set, to avoid unnecessary build of 16-bit
tables.
Version 1.4.0rc02 [December 20, 2009]
Declared png_cleanup_needed "volatile" in pngread.c and pngwrite.c
Version 1.4.0rc03 [December 22, 2009]
Renamed libpng-pc.in back to libpng.pc.in and revised CMakeLists.txt
(revising the change in 1.4.0beta99)
Version 1.4.0rc04 [December 25, 2009]
Swapped PNG_UNKNOWN_CHUNKS_SUPPORTED and PNG_HANDLE_AS_UNKNOWN_SUPPORTED
in pngset.c to be consistent with other changes in version 1.2.38.
Version 1.4.0rc05 [December 25, 2009]
Changed "libpng-pc.in" to "libpng.pc.in" in configure.ac, configure, and
Makefile.in to be consistent with changes in libpng-1.4.0rc03
Version 1.4.0rc06 [December 29, 2009]
Reverted the gamma_table changes from libpng-1.4.0beta109.
Fixed some indentation errors.
Version 1.4.0rc07 [January 1, 2010]
Revised libpng*.txt and libpng.3 about 1.2.x->1.4.x differences.
Use png_calloc() instead of png_malloc(); png_memset() in pngrutil.c
Update copyright year to 2010.
Version 1.4.0rc08 [January 2, 2010]
Avoid deprecated references to png_ptr-io_ptr and png_ptr->error_ptr
in pngtest.c
Version 1.4.0 [January 3, 2010]
No changes.
Version 1.4.1beta01 [January 8, 2010]
Updated CMakeLists.txt for consistent indentation and to avoid an
unclosed if-statement warning (Philip Lowman).
Revised Makefile.am and Makefile.in to remove references to Y2KINFO,
KNOWNBUG, and libpng.la (Robert Schwebel).
Revised the makefiles to install the same files and symbolic
links as configure, except for libpng.la and libpng14.la.
Make png_set|get_compression_buffer_size() available even when
PNG_WRITE_SUPPORTED is not enabled.
Revised Makefile.am and Makefile.in to simplify their maintenance.
Revised scripts/makefile.linux to install a link to libpng14.so.14.1
Version 1.4.1beta02 [January 9, 2010]
Revised the rest of the makefiles to install a link to libpng14.so.14.1
Version 1.4.1beta03 [January 10, 2010]
Removed png_set_premultiply_alpha() from scripts/*.def
Version 1.4.1rc01 [January 16, 2010]
No changes.
Version 1.4.1beta04 [January 23, 2010]
Revised png_decompress_chunk() to improve speed and memory usage when
decoding large chunks.
Added png_set|get_chunk_malloc_max() functions.
Version 1.4.1beta05 [January 26, 2010]
Relocated "int k" declaration in pngtest.c to minimize its scope.
Version 1.4.1beta06 [January 28, 2010]
Revised png_decompress_chunk() to use a two-pass method suggested by
John Bowler.
Version 1.4.1beta07 [February 6, 2010]
Folded some long lines in the source files.
Added defineable PNG_USER_CHUNK_CACHE_MAX, PNG_USER_CHUNK_MALLOC_MAX,
and a PNG_USER_LIMITS_SUPPORTED flag.
Eliminated use of png_ptr->irowbytes and reused the slot in png_ptr as
png_ptr->png_user_chunk_malloc_max.
Revised png_push_save_buffer() to do fewer but larger png_malloc() calls.
Version 1.4.1beta08 [February 6, 2010]
Minor cleanup and updating of dates and copyright year.
Version 1.5.0beta01 [February 7, 2010]
Moved declaration of png_struct into private pngstruct.h and png_info
into pnginfo.h
Version 1.4.1beta09 and 1.5.0beta02 [February 7, 2010]
Reverted to original png_push_save_buffer() code.
Version 1.4.1beta10 and 1.5.0beta03 [February 8, 2010]
Return allocated "old_buffer" in png_push_save_buffer() before
calling png_error(), to avoid a potential memory leak.
Updated configure script to use SO number 15.
Version 1.5.0beta04 [February 9, 2010]
Removed malformed "incomplete struct declaration" of png_info from png.h
Version 1.5.0beta05 [February 12, 2010]
Removed PNG_DEPSTRUCT markup in pngstruct.h and pnginfo.h, and undid the
linewrapping that it entailed.
Revised comments in pngstruct.h and pnginfo.h and added pointers to
the libpng license.
Changed PNG_INTERNAL to PNG_EXPOSE_INTERNAL_STRUCTURES
Removed the cbuilder5 project, which has not been updated to 1.4.0.
Version 1.4.1beta12 and 1.5.0beta06 [February 14, 2010]
Fixed type declaration of png_get_chunk_malloc_max() in pngget.c (Daisuke
Nishikawa)
Version 1.5.0beta07 [omitted]
Version 1.5.0beta08 [February 19, 2010]
Changed #ifdef PNG_NO_STDIO_SUPPORTED to #ifdef PNG_NO_CONSOLE_IO_SUPPORTED
wherever png_snprintf() is used to construct error and warning messages.
Noted in scripts/makefile.mingw that it expects to be run under MSYS.
Removed obsolete unused MMX-querying support from contrib/gregbook
Added exported png_longjmp() function.
Removed the AIX redefinition of jmpbuf in png.h
Added -D_ALLSOURCE in configure.ac, makefile.aix, and CMakeLists.txt
when building on AIX.
Version 1.5.0beta09 [February 19, 2010]
Removed -D_ALLSOURCE from configure.ac, makefile.aix, and CMakeLists.txt.
Changed the name of png_ptr->jmpbuf to png_ptr->png_jmpbuf in pngstruct.h
Version 1.5.0beta10 [February 25, 2010]
Removed unused gzio.c from contrib/pngminim gather and makefile scripts
Removed replacement error handlers from contrib/gregbook. Because of
the new png_longjmp() function they are no longer needed.
Version 1.5.0beta11 [March 6, 2010]
Removed checking for already-included setjmp.h from pngconf.h
Fixed inconsistent indentations and made numerous cosmetic changes.
Revised the "SEE ALSO" style of libpng.3, libpngpf.3, and png.5
Version 1.5.0beta12 [March 9, 2010]
Moved "#include png.h" inside pngpriv.h and removed "#include png.h" from
the source files, along with "#define PNG_EXPOSE_INTERNAL_STRUCTURES"
and "#define PNG_NO_PEDANTIC_WARNINGS" (John Bowler).
Created new pngdebug.h and moved debug definitions there.
Version 1.5.0beta13 [March 10, 2010]
Protect pngstruct.h, pnginfo.h, and pngdebug.h from being included twice.
Revise the "#ifdef" blocks in png_inflate() so it will compile when neither
PNG_USER_CHUNK_MALLOC_MAX nor PNG_SET_CHUNK_MALLOC_LIMIT_SUPPORTED
is defined.
Removed unused png_measure_compressed_chunk() from pngpriv.h and libpngpf.3
Moved the 'config.h' support from pngconf.h to pngpriv.h
Removed PNGAPI from the png_longjmp_ptr typedef.
Eliminated dependence of pngtest.c on the private pngdebug.h file.
Make all png_debug macros into *unterminated* statements or
expressions (i.e. a trailing ';' must always be added) and correct
the format statements in various png_debug messages.
Version 1.5.0beta14 [March 14, 2010]
Removed direct access to png_ptr->io_ptr from the Windows code in pngtest.c
Revised Makefile.am to account for recent additions and replacements.
Corrected CE and OS/2 DEF files (scripts/png*def) for symbols removed and
added ordinal numbers to the Windows DEF file and corrected the duplicated
ordinal numbers on CE symbols that are commented out.
Added back in export symbols that can be present in the Windows build but
are disabled by default.
PNG_EXPORT changed to include an 'ordinal' field for DEF file generation.
PNG_CALLBACK added to make callback definitions uniform. PNGAPI split
into PNGCAPI (base C form), PNGAPI (exports) and PNGCBAPI (callbacks),
and appropriate changes made to all files. Cygwin builds re-hinged to
allow procedure call standard changes and to remove the need for the DEF
file (fixes build on Cygwin).
Enabled 'attribute' warnings that are relevant to library APIs and callbacks.
Changed rules for generation of the various symbol files and added a new
rule for a DEF file (which is also added to the distribution).
Updated the symbol file generation to stop it adding spurious spaces
to EOL (coming from preprocessor macro expansion). Added a facility
to join tokens in the output and rewrite *.dfn to use this.
Eliminated scripts/*.def in favor of libpng.def; updated projects/visualc71
and removed scripts/makefile.cygwin.
Made PNG_BUILD_DLL safe: it can be set whenever a DLL is being built.
Removed the include of sys/types.h - apparently unnecessary now on the
platforms on which it happened (all but Mac OS and RISC OS).
Moved the Mac OS test into pngpriv.h (the only place it is used.)
Version 1.5.0beta15 [March 17, 2010]
Added symbols.chk target to Makefile.am to validate the symbols in png.h
against the new DEF file scripts/symbols.def.
Changed the default DEF file back to pngwin.def.
Removed makefile.mingw.
Eliminated PNG_NO_EXTERN and PNG_ALL_EXTERN
Version 1.5.0beta16 [April 1, 2010]
Make png_text_struct independent of PNG_iTXt_SUPPORTED, so that
fields are initialized in all configurations. The READ/WRITE
macros (PNG_(READ|WRITE)_iTXt_SUPPORTED) still function as
before to disable code to actually read or write iTXt chunks
and iTXt_SUPPORTED can be used to detect presence of either
read or write support (but it is probably better to check for
the one actually required - read or write.)
Combined multiple png_warning() calls for a single error.
Restored the macro definition of png_check_sig().
Version 1.5.0beta17 [April 17, 2010]
Added some "(long)" typecasts to printf calls in png_handle_cHRM().
Documented the fact that png_set_dither() was disabled since libpng-1.4.0.
Reenabled png_set_dither() but renamed it to png_set_quantize() to reflect
more accurately what it actually does. At the same time, renamed
the PNG_DITHER_[RED,GREEN_BLUE]_BITS macros to
PNG_QUANTIZE_[RED,GREEN,BLUE]_BITS.
Added some "(long)" typecasts to printf calls in png_handle_cHRM().
Freeze build-time only configuration in the build.
In all prior versions of libpng most configuration options
controlled by compiler #defines had to be repeated by the
application code that used libpng. This patch changes this
so that compilation options that can only be changed at build
time are frozen in the build. Options that are compiler
dependent (and those that are system dependent) are evaluated
each time - pngconf.h holds these. Options that can be changed
per-file in the application are in png.h. Frozen options are
in the new installed header file pnglibconf.h (John Bowler)
Removed the xcode project because it has not been updated to work
with libpng-1.5.0.
Removed the ability to include optional pngusr.h
Version 1.5.0beta18 [April 17, 2010]
Restored the ability to include optional pngusr.h
Moved replacements for png_error() and png_warning() from the
contrib/pngminim project to pngerror.c, for use when warnings or
errors are disabled via PNG_NO_WARN or PNG_NO_ERROR_TEXT, to avoid
storing unneeded error/warning text.
Updated contrib/pngminim project to work with the new pnglibconf.h
Added some PNG_NO_* defines to contrib/pngminim/*/pngusr.h to save space.
Version 1.5.0beta19 [April 24, 2010]
Added PNG_{READ,WRITE}_INT_FUNCTIONS_SUPPORTED. This allows the functions
to read and write ints to be disabled independently of PNG_USE_READ_MACROS,
which allows libpng to be built with the functions even though the default
is to use the macros - this allows applications to choose at app build
time whether or not to use macros (previously impossible because the
functions weren't in the default build.)
Changed Windows calling convention back to __cdecl for API functions.
For Windows/x86 platforms only:
__stdcall is no longer needed for Visual Basic, so libpng-1.5.0 uses
__cdecl throughout (both API functions and callbacks) on Windows/x86
platforms.
Replaced visualc6 and visualc71 projects with new vstudio project
Relaxed the overly-restrictive permissions of some files.
Version 1.5.0beta20 [April 24, 2010]
Relaxed more overly-restrictive permissions of some files.
Version 1.5.0beta21 [April 27, 2010]
Removed some unwanted binary bytes and changed CRLF to NEWLINE in the new
vstudio project files, and some trivial editing of some files in the
scripts directory.
Set PNG_NO_READ_BGR, PNG_NO_IO_STATE, and PNG_NO_TIME_RFC1123 in
contrib/pngminim/decoder/pngusr.h to make a smaller decoder application.
Version 1.5.0beta22 [April 28, 2010]
Fixed dependencies of GET_INT_32 - it does not require READ_INT_FUNCTIONS
because it has a macro equivalent.
Improved the options.awk script; added an "everything off" option.
Revised contrib/pngminim to use the "everything off" option in pngusr.dfa.
Version 1.5.0beta23 [April 29, 2010]
Corrected PNG_REMOVED macro to take five arguments.
The macro was documented with two arguments (name,ordinal), however
the symbol checking .dfn files assumed five arguments. The five
argument form seems more useful so it is changed to that.
Corrected PNG_UNKNOWN_CHUNKS_SUPPORTED to PNG_HANDLE_AS_UNKNOWN_SUPPORTED
in gregbook/readpng2.c
Corrected protection of png_get_user_transform_ptr. The API declaration in
png.h is removed if both READ and WRITE USER_TRANSFORM are turned off
but was left defined in pngtrans.c
Added logunsupported=1 to cause pnglibconf.h to document disabled options.
This makes the installed pnglibconf.h more readable but causes no
other change. The intention is that users of libpng will find it
easier to understand if an API they need is missing.
Include png_reset_zstream() in png.c only when PNG_READ_SUPPORTED is defined.
Removed dummy_inflate.c from contrib/pngminim/encoder
Removed contrib/pngminim/*/gather.sh; gathering is now done in the makefile.
Version 1.5.0beta24 [May 7, 2010]
Use bitwise "&" instead of arithmetic mod in pngrutil.c calculation of the
offset of the png_ptr->rowbuf pointer into png_ptr->big_row_buf.
Added more blank lines for readability.
Version 1.5.0beta25 [June 18, 2010]
In pngpread.c: png_push_have_row() add check for new_row > height
Removed the now-redundant check for out-of-bounds new_row from example.c
Version 1.5.0beta26 [June 18, 2010]
In pngpread.c: png_push_process_row() add check for too many rows.
Version 1.5.0beta27 [June 18, 2010]
Removed the check added in beta25 as it is now redundant.
Version 1.5.0beta28 [June 20, 2010]
Rewrote png_process_IDAT_data to consistently treat extra data as warnings
and handle end conditions more cleanly.
Removed the new (beta26) check in png_push_process_row().
Version 1.5.0beta29 [June 21, 2010]
Revised scripts/options.awk to work on Sunos (but still doesn't work)
Added comment to options.awk and contrib/pngminim/*/makefile to try nawk.
Version 1.5.0beta30 [June 22, 2010]
Stop memory leak when reading a malformed sCAL chunk.
Version 1.5.0beta31 [June 26, 2010]
Revised pngpread.c patch of beta28 to avoid an endless loop.
Removed some trailing blanks.
Version 1.5.0beta32 [June 26, 2010]
Removed leftover scripts/options.patch and scripts/options.rej
Version 1.5.0beta33 [July 6, 3010]
Made FIXED and FLOATING options consistent in the APIs they enable and
disable. Corrected scripts/options.awk to handle both command line
options and options specified in the .dfa files.
Changed char *msg to PNG_CONST char *msg in pngrutil.c
Make png_set_sRGB_gAMA_and_cHRM set values using either the fixed or
floating point APIs, but not both.
Reversed patch to remove error handler when the jmp_buf is stored in the
main program structure, not the png_struct.
The error handler is needed because the default handler in libpng will
always use the jmp_buf in the library control structure; this is never
set. The gregbook code is a useful example because, even though it
uses setjmp/longjmp, it shows how error handling can be implemented
using control mechanisms not directly supported by libpng. The
technique will work correctly with mechanisms such as Microsoft
Structure Exceptions or C++ exceptions (compiler willing - note that gcc
does not by default support interworking of C and C++ error handling.)
Reverted changes to call png_longjmp in contrib/gregbook where it is not
appropriate. If mainprog->jmpbuf is used by setjmp, then png_longjmp
cannot be used.
Changed "extern PNG_EXPORT" to "PNG_EXPORT" in png.h (Jan Nijtmans)
Changed "extern" to "PNG_EXTERN" in pngpriv.h (except for the 'extern "C" {')
Version 1.5.0beta34 [July 12, 2010]
Put #ifndef PNG_EXTERN, #endif around the define PNG_EXTERN in pngpriv.h
Version 1.5.0beta35 [July 24, 2010]
Removed some newly-added TAB characters.
Added -DNO_PNG_SNPRINTF to CFLAGS in scripts/makefile.dj2
Moved the definition of png_snprintf() outside of the enclosing
#ifdef blocks in pngconf.h
Version 1.5.0beta36 [July 29, 2010]
Patches by John Bowler:
Fixed point APIs are now supported throughout (no missing APIs).
Internal fixed point arithmetic support exists for all internal floating
point operations.
sCAL validates the floating point strings it is passed.
Safe, albeit rudimentary, Watcom support is provided by PNG_API_RULE==2
Two new APIs exist to get the number of passes without turning on the
PNG_INTERLACE transform and to get the number of rows in the current
pass.
A new test program, pngvalid.c, validates the gamma code.
Errors in the 16-bit gamma correction (overflows) have been corrected.
cHRM chunk testing is done consistently (previously the floating point
API bypassed it, because the test really didn't work on FP, now the test
is performed on the actual values to be stored in the PNG file so it
works in the FP case too.)
Most floating point APIs now simply call the fixed point APIs after
converting the values to the fixed point form used in the PNG file.
The standard headers no longer include zlib.h, which is currently only
required for pngstruct.h and can therefore be internal.
Revised png_get_int_32 to undo the PNG two's complement representation of
negative numbers.
Version 1.5.0beta37 [July 30, 2010]
Added a typecast in png_get_int_32() in png.h and pngrutil.h to avoid
a compiler warning.
Replaced oFFs 0,0 with oFFs -10,20 in pngtest.png
Version 1.5.0beta38 [July 31, 2010]
Implemented remaining "_fixed" functions.
Corrected a number of recently introduced warnings mostly resulting from
safe but uncast assignments to shorter integers. Also added a zlib
VStudio release library project because the latest zlib Official Windows
build does not include such a thing.
Revised png_get_int_16() to be similar to png_get_int_32().
Restored projects/visualc71.
Version 1.5.0beta39 [August 2, 2010]
VisualC/GCC warning fixes, VisualC build fixes
The changes include support for function attributes in VC in addition to
those already present in GCC - necessary because without these some
warnings are unavoidable. Fixes include signed/unsigned fixes in
pngvalid and checks with gcc -Wall -Wextra -Wunused.
VC requires function attributes on function definitions as well as
declarations, PNG_FUNCTION has been added to enable this and the
relevant function definitions changed.
Version 1.5.0beta40 [August 6, 2010]
Correct use of _WINDOWS_ in pngconf.h
Removed png_mem_ #defines; they are no longer used.
Added the sRGB chunk to pngtest.png
Version 1.5.0beta41 [August 11, 2010]
Added the cHRM chunk to pngtest.png
Don't try to use version-script with cygwin/mingw.
Revised contrib/gregbook to work under cygwin/mingw.
Version 1.5.0beta42 [August 18, 2010]
Add .dll.a to the list of extensions to be symlinked by Makefile.am (Yaakov)
Made all API functions that have const arguments and constant string
literal pointers declare them (John Bowler).
Version 1.5.0beta43 [August 20, 2010]
Removed spurious tabs, shorten long lines (no source change)
Also added scripts/chkfmt to validate the format of all the files that can
reasonably be validated (it is suggested to run "make distclean" before
checking, because some machine generated files have long lines.)
Reformatted the CHANGES file to be more consistent throughout.
Made changes to address various issues identified by GCC, mostly
signed/unsigned and shortening problems on assignment but also a few
difficult to optimize (for GCC) loops.
Fixed non-GCC fixed point builds. In png.c a declaration was misplaced
in an earlier update. Fixed to declare the auto variables at the head.
Use cexcept.h in pngvalid.c.
Version 1.5.0beta44 [August 24, 2010]
Updated CMakeLists.txt to use CMAKE_INSTALL_LIBDIR variable; useful for
installing libpng in /usr/lib64 (Funda Wang).
Revised CMakeLists.txt to put the man pages in share/man/man* not man/man*
Revised CMakeLists.txt to make symlinks instead of copies when installing.
Changed PNG_LIB_NAME from pngNN to libpngNN in CMakeLists.txt (Philip Lowman)
Implemented memory checks within pngvalid
Reformatted/rearranged pngvalid.c to assist use of progressive reader.
Check interlaced images in pngvalid
Clarified pngusr.h comments in pnglibconf.dfa
Simplified the pngvalid error-handling code now that cexcept.h is in place.
Implemented progressive reader in pngvalid.c for standard tests
Implemented progressive read in pngvalid.c gamma tests
Turn on progressive reader in pngvalid.c by default and tidy code.
Version 1.5.0beta45 [August 26, 2010]
Added an explicit make step to projects/vstudio for pnglibconf.h
Also corrected zlib.vcxproj into which Visual Studio had introduced
what it calls an "authoring error". The change to make pnglibconf.h
simply copies the file; in the future it may actually generate the
file from scripts/pnglibconf.dfa as the other build systems do.
Changed pngvalid to work when floating point APIs are disabled
Renamed the prebuilt scripts/pnglibconf.h to scripts/pnglibconf.h.prebuilt
Supply default values for PNG_USER_PRIVATEBUILD and PNG_USER_DLLFNAME_POSTFIX
in pngpriv.h in case the user neglected to define them in their pngusr.h
Version 1.5.0beta46 [August 28, 2010]
Added new private header files to libpng_sources in CMakeLists.txt
Added PNG_READ_16BIT, PNG_WRITE_16BIT, and PNG_16BIT options.
Added reference to scripts/pnglibconf.h.prebuilt in the visualc71 project.
Version 1.5.0beta47 [September 11, 2010]
Fixed a number of problems with 64-bit compilation reported by Visual
Studio 2010 (John Bowler).
Version 1.5.0beta48 [October 4, 2010]
Updated CMakeLists.txt (Philip Lowman).
Revised autogen.sh to recognize and use $AUTOCONF, $AUTOMAKE, $AUTOHEADER,
$AUTOPOINT, $ACLOCAL and $LIBTOOLIZE
Fixed problem with symbols creation in Makefile.am which was assuming that
all versions of ccp write to standard output by default (Martin Banky). The
bug was introduced in libpng-1.2.9beta5.
Removed unused mkinstalldirs.
Version 1.5.0beta49 [October 8, 2010]
Undid Makefile.am revision of 1.5.0beta48.
Version 1.5.0beta50 [October 14, 2010]
Revised Makefile.in to account for mkinstalldirs being removed.
Added some "(unsigned long)" typecasts in printf statements in pngvalid.c.
Suppressed a compiler warning in png_handle_sPLT().
Check for out-of-range text compression mode in png_set_text().
Version 1.5.0beta51 [October 15, 2010]
Changed embedded dates to "(PENDING RELEASE) in beta releases (and future
rc releases) to minimize the difference between releases.
Version 1.5.0beta52 [October 16, 2010]
Restored some of the embedded dates (in png.h, png.c, documentation, etc.)
Version 1.5.0beta53 [October 18, 2010]
Updated INSTALL to mention using "make maintainer-clean" and to remove
obsolete statement about a custom ltmain.sh
Disabled "color-tests" by default in Makefile.am so it will work with
automake versions earlier than 1.11.1
Use document name "libpng-manual.txt" instead of "libpng-<version>.txt"
to simplify version differences.
Removed obsolete remarks about setjmp handling from INSTALL.
Revised and renamed the typedef in png.h and png.c that was designed
to catch library and header mismatch.
Version 1.5.0beta54 [November 10, 2010]
Require 48 bytes, not 64 bytes, for big_row_buf in overflow checks.
Used a consistent structure for the pngget.c functions.
Version 1.5.0beta55 [November 21, 2010]
Revised png_get_uint_32, png_get_int_32, png_get_uint_16 (Cosmin)
Moved reading of file signature into png_read_sig (Cosmin)
Fixed atomicity of chunk header serialization (Cosmin)
Added test for io_state in pngtest.c (Cosmin)
Added "#!/bin/sh" at the top of contrib/pngminim/*/gather.sh scripts.
Changes to remove gcc warnings (John Bowler)
Certain optional gcc warning flags resulted in warnings in libpng code.
With these changes only -Wconversion and -Wcast-qual cannot be turned on.
Changes are trivial rearrangements of code. -Wconversion is not possible
for pngrutil.c (because of the widespread use of += et al on variables
smaller than (int) or (unsigned int)) and -Wcast-qual is not possible
with pngwio.c and pngwutil.c because the 'write' callback and zlib
compression both fail to declare their input buffers with 'const'.
Version 1.5.0beta56 [December 7, 2010]
Added the private PNG_UNUSED() macro definition in pngpriv.h.
Added some commentary about PNG_EXPORT in png.h and pngconf.h
Revised PNG_EXPORT() macro and added PNG_EXPORTA() macro, with the
objective of simplifying and improving the cosmetic appearance of png.h.
Fixed some incorrect "=" macro names in pnglibconf.dfa
Included documentation of changes in 1.5.0 from 1.4.x in libpng-manual.txt
Version 1.5.0beta57 [December 9, 2010]
Documented the pngvalid gamma error summary with additional comments and
print statements.
Improved missing symbol handling in checksym.awk; symbols missing in both
the old and new files can now be optionally ignored, treated as errors
or warnings.
Removed references to pngvcrd.c and pnggccrd.c from the vstudio project.
Updated "libpng14" to "libpng15" in the visualc71 project.
Enabled the strip16 tests in pngvalid.`
Don't display test results (except PASS/FAIL) when running "make test".
Instead put them in pngtest-log.txt
Added "--with-zprefix=<string>" to configure.ac
Updated the prebuilt configuration files to autoconf version 2.68
Version 1.5.0beta58 [December 19, 2010]
Fixed interlace image handling and add test cases (John Bowler)
Fixed the clean rule in Makefile.am to remove pngtest-log.txt
Made minor changes to work around warnings in gcc 3.4
Version 1.5.0rc01 [December 27, 2010]
No changes.
Version 1.5.0rc02 [December 27, 2010]
Eliminated references to the scripts/*.def files in project/visualc71.
Version 1.5.0rc03 [December 28, 2010]
Eliminated scripts/*.def and revised Makefile.am accordingly
Version 1.5.0rc04 [December 29, 2010]
Fixed bug in background transformation handling in pngrtran.c (it was
looking for the flag in png_ptr->transformations instead of in
png_ptr->flags) (David Raymond).
Version 1.5.0rc05 [December 31, 2010]
Fixed typo in a comment in CMakeLists.txt (libpng14 => libpng15) (Cosmin)
Version 1.5.0rc06 [January 4, 2011]
Changed the new configure option "zprefix=string" to "zlib-prefix=string"
Version 1.5.0rc07 [January 4, 2011]
Updated copyright year.
Version 1.5.0 [January 6, 2011]
No changes.
version 1.5.1beta01 [January 8, 2011]
Added description of png_set_crc_action() to the manual.
Added a note in the manual that the type of the iCCP profile was changed
from png_charpp to png_bytepp in png_get_iCCP(). This change happened
in version 1.5.0beta36 but is not noted in the CHANGES. Similarly,
it was changed from png_charpp to png_const_bytepp in png_set_iCCP().
Ensure that png_rgb_to_gray ignores palette mapped images, if libpng
internally happens to call it with one, and fixed a failure to handle
palette mapped images correctly. This fixes CVE-2690.
Version 1.5.1beta02 [January 14, 2011]
Fixed a bug in handling of interlaced images (bero at arklinux.org).
Updated CMakeLists.txt (Clifford Yapp)
Version 1.5.1beta03 [January 14, 2011]
Fixed typecasting of some png_debug() statements (Cosmin)
Version 1.5.1beta04 [January 16, 2011]
Updated documentation of png_set|get_tRNS() (Thomas Klausner).
Mentioned in the documentation that applications must #include "zlib.h"
if they need access to anything in zlib.h, and that a number of
macros such as png_memset() are no longer accessible by applications.
Corrected pngvalid gamma test "sample" function to access all of the color
samples of each pixel, instead of sampling the red channel three times.
Prefixed variable names index, div, exp, gamma with "png_" to avoid "shadow"
warnings, and (mistakenly) changed png_exp() to exp().
Version 1.5.1beta05 [January 16, 2011]
Changed variable names png_index, png_div, png_exp, and png_gamma to
char_index, divisor, exp_b10, and gamma_val, respectively, and
changed exp() back to png_exp().
Version 1.5.1beta06 [January 20, 2011]
Prevent png_push_crc_skip() from hanging while reading an unknown chunk
or an over-large compressed zTXt chunk with the progressive reader.
Eliminated more GCC "shadow" warnings.
Revised png_fixed() in png.c to avoid compiler warning about reaching the
end without returning anything.
Version 1.5.1beta07 [January 22, 2011]
In the manual, describe the png_get_IHDR() arguments in the correct order.
Added const_png_structp and const_png_infop types, and used them in
prototypes for most png_get_*() functions.
Version 1.5.1beta08 [January 23, 2011]
Added png_get_io_chunk_type() and deprecated png_get_io_chunk_name()
Added synopses for the IO_STATE functions and other missing synopses
to the manual. Removed the synopses from libpngpf.3 because they
were out of date and no longer useful. Better information can be
obtained by reading the prototypes and comments in pngpriv.h
Attempted to fix cpp on Solaris with S. Studio 12 cc, fix build
Added a make macro DFNCPP that is a CPP that will accept the tokens in
a .dfn file and adds configure stuff to test for such a CPP. ./configure
should fail if one is not available.
Corrected const_png_ in png.h to png_const_ to avoid polluting the namespace.
Added png_get_current_row_number and png_get_current_pass_number for the
benefit of the user transform callback.
Added png_process_data_pause and png_process_data_skip for the benefit of
progressive readers that need to stop data processing or want to optimize
skipping of unread data (e.g., if the reader marks a chunk to be skipped.)
Version 1.5.1beta09 [January 24, 2011]
Enhanced pngvalid, corrected an error in gray_to_rgb, corrected doc error.
pngvalid contains tests of transforms, which tests are currently disabled
because they are incompletely tested. gray_to_rgb was failing to expand
the bit depth for smaller bit depth images; this seems to be a long
standing error and resulted, apparently, in invalid output
(CVE-2011-0408, CERT VU#643140). The documentation did not accurately
describe what libpng really does when converting RGB to gray.
Version 1.5.1beta10 [January 27, 2010]
Fixed incorrect examples of callback prototypes in the manual, that were
introduced in libpng-1.0.0.
In addition the order of the png_get_uint macros with respect to the
relevant function definitions has been reversed. This helps the
preprocessing of the symbol files be more robust. Furthermore, the
symbol file preprocessing now uses -DPNG_NO_USE_READ_MACROS even when
the library may actually be built with PNG_USE_READ_MACROS; this stops
the read macros interfering with the symbol file format.
Made the manual, synopses, and function prototypes use the function
argument names file_gamma, int_file_gamma, and srgb_intent consistently.
Version 1.5.1beta11 [January 28, 2011]
Changed PNG_UNUSED from "param=param;" to "{if(param){}}".
Corrected local variable type in new API png_process_data_skip()
The type was self-evidently incorrect but only causes problems on 64-bit
architectures.
Added transform tests to pngvalid and simplified the arguments.
Version 1.5.1rc01 [January 29, 2011]
No changes.
Version 1.5.1rc02 [January 31, 2011]
Added a request in the manual that applications do not use "png_" or
"PNG_" to begin any of their own symbols.
Changed PNG_UNUSED to "(void)param;" and updated the commentary in pngpriv.h
Version 1.5.1 [February 3, 2011]
No changes.
Version 1.5.2beta01 [February 13, 2011]
More -Wshadow fixes for older gcc compilers. Older gcc versions apparently
check formal parameters names in function declarations (as well as
definitions) to see if they match a name in the global namespace.
Revised PNG_EXPORTA macro to not use an empty parameter, to accommodate the
old VisualC++ preprocessor.
Turned on interlace handling in png_read_png().
Fixed gcc pendantic warnings.
Handle longjmp in Cygwin.
Fixed png_get_current_row_number() in the interlaced case.
Cleaned up ALPHA flags and transformations.
Implemented expansion to 16 bits.
Version 1.5.2beta02 [February 19, 2011]
Fixed mistake in the descriptions of user read_transform and write_transform
function prototypes in the manual. The row_info struct is png_row_infop.
Reverted png_get_current_row_number() to previous (1.5.2beta01) behavior.
Corrected png_get_current_row_number documentation
Fixed the read/write row callback documentation.
This documents the current behavior, where the callback is called after
every row with information pertaining to the next row.
Version 1.5.2beta03 [March 3, 2011]
Fixed scripts/makefile.vcwin32
Updated contrib/pngsuite/README to add the word "modify".
Define PNG_ALLOCATED to blank when _MSC_VER<1300.
Version 1.5.2rc01 [March 19, 2011]
Define remaining attributes to blank when MSC_VER<1300.
ifdef out mask arrays in pngread.c when interlacing is not supported.
Version 1.5.2rc02 [March 22, 2011]
Added a hint to try CPP=/bin/cpp if "cpp -E" fails in scripts/pnglibconf.mak
and in contrib/pngminim/*/makefile, eg., on SunOS 5.10, and removed "strip"
from the makefiles.
Fixed a bug (present since libpng-1.0.7) that makes png_handle_sPLT() fail
to compile when PNG_NO_POINTER_INDEXING is defined (Chubanov Kirill)
Version 1.5.2rc03 [March 24, 2011]
Don't include standard header files in png.h while building the symbol table,
to avoid cpp failure on SunOS (introduced PNG_BUILDING_SYMBOL_TABLE macro).
Version 1.5.2 [March 31, 2011]
No changes.
Version 1.5.3beta01 [April 1, 2011]
Re-initialize the zlib compressor before compressing non-IDAT chunks.
Added API functions (png_set_text_compression_level() and four others) to
set parameters for zlib compression of non-IDAT chunks.
Version 1.5.3beta02 [April 3, 2011]
Updated scripts/symbols.def with new API functions.
Only compile the new zlib re-initializing code when text or iCCP is
supported, using PNG_WRITE_COMPRESSED_TEXT_SUPPORTED macro.
Improved the optimization of the zlib CMF byte (see libpng-1.2.6beta03).
Optimize the zlib CMF byte in non-IDAT compressed chunks
Version 1.5.3beta03 [April 16, 2011]
Fixed gcc -ansi -pedantic compile. A strict ANSI system does not have
snprintf, and the "__STRICT_ANSI__" detects that condition more reliably
than __STDC__ (John Bowler).
Removed the PNG_PTR_NORETURN attribute because it too dangerous. It tells
the compiler that a user supplied callback (the error handler) does not
return, yet there is no guarantee in practice that the application code
will correctly implement the error handler because the compiler only
issues a warning if there is a mistake (John Bowler).
Removed the no-longer-used PNG_DEPSTRUCT macro.
Updated the zlib version to 1.2.5 in the VStudio project.
Fixed 64-bit builds where png_uint_32 is smaller than png_size_t in
pngwutil.c (John Bowler).
Fixed bug with stripping the filler or alpha channel when writing, that
was introduced in libpng-1.5.2beta01 (bug report by Andrew Church).
Version 1.5.3beta04 [April 27, 2011]
Updated pngtest.png with the new zlib CMF optimization.
Cleaned up conditional compilation code and of background/gamma handling
Internal changes only except a new option to avoid compiling the
png_build_grayscale_palette API (which is not used at all internally.)
The main change is to move the transform tests (READ_TRANSFORMS,
WRITE_TRANSFORMS) up one level to the caller of the APIs. This avoids
calls to spurious functions if all transforms are disabled and slightly
simplifies those functions. Pngvalid modified to handle this.
A minor change is to stop the strip_16 and expand_16 interfaces from
disabling each other; this allows the future alpha premultiplication
code to use 16-bit intermediate values while still producing 8-bit output.
png_do_background and png_do_gamma have been simplified to take a single
pointer to the png_struct rather than pointers to every item required
from the png_struct. This makes no practical difference to the internal
code.
A serious bug in the pngvalid internal routine 'standard_display_init' has
been fixed - this failed to initialize the red channel and accidentally
initialized the alpha channel twice.
Changed png_struct jmp_buf member name from png_jmpbuf to tmp_jmpbuf to
avoid a possible clash with the png_jmpbuf macro on some platforms.
Version 1.5.3beta05 [May 6, 2011]
Added the "_POSIX_SOURCE" feature test macro to ensure libpng sees the
correct API. _POSIX_SOURCE is defined in pngpriv.h, pngtest.c and
pngvalid.c to ensure that POSIX conformant systems disable non-POSIX APIs.
Removed png_snprintf and added formatted warning messages. This change adds
internal APIs to allow png_warning messages to have parameters without
requiring the host OS to implement snprintf. As a side effect the
dependency of the tIME-supporting RFC1132 code on stdio is removed and
PNG_NO_WARNINGS does actually work now.
Pass "" instead of '\0' to png_default_error() in png_err(). This mistake
was introduced in libpng-1.2.20beta01. This fixes CVE-2011-2691.
Added PNG_WRITE_OPTIMIZE_CMF_SUPPORTED macro to make the zlib "CMF" byte
optimization configureable.
IDAT compression failed if preceded by a compressed text chunk (bug
introduced in libpng-1.5.3beta01-02). This was because the attempt to
reset the zlib stream in png_write_IDAT happened after the first IDAT
chunk had been deflated - much too late. In this change internal
functions were added to claim/release the z_stream and, hopefully, make
the code more robust. Also deflateEnd checking is added - previously
libpng would ignore an error at the end of the stream.
Version 1.5.3beta06 [May 8, 2011]
Removed the -D_ALL_SOURCE from definitions for AIX in CMakeLists.txt
Implemented premultiplied alpha support: png_set_alpha_mode API
Version 1.5.3beta07 [May 11, 2011]
Added expand_16 support to the high level interface.
Added named value and 'flag' gamma support to png_set_gamma. Made a minor
change from the previous (unreleased) ABI/API to hide the exact value used
for Macs - it's not a good idea to embed this in the ABI!
Moved macro definitions for PNG_HAVE_IHDR, PNG_HAVE_PLTE, and PNG_AFTER_IDAT
from pngpriv.h to png.h because they must be visible to applications
that call png_set_unknown_chunks().
Check for up->location !PNG_AFTER_IDAT when writing unknown chunks
before IDAT.
Version 1.5.3beta08 [May 16, 2011]
Improved "pngvalid --speed" to exclude more of pngvalid from the time.
Documented png_set_alpha_mode(), other changes in libpng.3/libpng-manual.txt
The cHRM chunk now sets the defaults for png_set_rgb_to_gray() (when negative
parameters are supplied by the caller), while in the absence of cHRM
sRGB/Rec 709 values are still used. This introduced a divide-by-zero
bug in png_handle_cHRM().
The bKGD chunk no longer overwrites the background value set by
png_set_background(), allowing the latter to be used before the file
header is read. It never performed any useful function to override
the default anyway.
Added memory overwrite and palette image checks to pngvalid.c
Previously palette image code was poorly checked. Since the transformation
code has a special palette path in most cases this was a severe weakness.
Minor cleanup and some extra checking in pngrutil.c and pngrtran.c. When
expanding an indexed image, always expand to RGBA if transparency is
present.
Version 1.5.3beta09 [May 17, 2011]
Reversed earlier 1.5.3 change of transformation order; move png_expand_16
back where it was. The change doesn't work because it requires 16-bit
gamma tables when the code only generates 8-bit ones. This fails
silently; the libpng code just doesn't do any gamma correction. Moving
the tests back leaves the old, inaccurate, 8-bit gamma calculations, but
these are clearly better than none!
Version 1.5.3beta10 [May 20, 2011]
png_set_background() and png_expand_16() did not work together correctly.
This problem is present in 1.5.2; if png_set_background is called with
need_expand false and the matching 16 bit color libpng erroneously just
treats it as an 8-bit color because of where png_do_expand_16 is in the
transform list. This simple fix reduces the supplied colour to 8-bits,
so it gets smashed, but this is better than the current behavior.
Added tests for expand16, more fixes for palette image tests to pngvalid.
Corrects the code for palette image tests and disables attempts to
validate palette colors.
Version 1.5.3rc01 [June 3, 2011]
No changes.
Version 1.5.3rc02 [June 8, 2011]
Fixed uninitialized memory read in png_format_buffer() (Bug report by
Frank Busse, CVE-2011-2501, related to CVE-2004-0421).
Version 1.5.3beta11 [June 11, 2011]
Fixed png_handle_sCAL which is broken in 1.5. This fixes CVE 2011-2692.
Added sCAL to pngtest.png
Revised documentation about png_set_user_limits() to say that it also affects
png writing.
Revised handling of png_set_user_limits() so that it can increase the
limit beyond the PNG_USER_WIDTH|HEIGHT_MAX; previously it could only
reduce it.
Make the 16-to-8 scaling accurate. Dividing by 256 with no rounding is
wrong (high by one) 25% of the time. Dividing by 257 with rounding is
wrong in 128 out of 65536 cases. Getting the right answer all the time
without division is easy.
Added "_SUPPORTED" to the PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION macro.
Added projects/owatcom, an IDE project for OpenWatcom to replace
scripts/makefile.watcom. This project works with OpenWatcom 1.9. The
IDE autogenerates appropriate makefiles (libpng.mk) for batch processing.
The project is configurable, unlike the Visual Studio project, so long
as the developer has an awk.
Changed png_set_gAMA to limit the gamma value range so that the inverse
of the stored value cannot overflow the fixed point representation,
and changed other things OpenWatcom warns about.
Revised pngvalid.c to test PNG_ALPHA_MODE_SUPPORTED correctly. This allows
pngvalid to build when ALPHA_MODE is not supported, which is required if
it is to build on libpng 1.4.
Removed string/memory macros that are no longer used and are not
necessarily fully supportable, particularly png_strncpy and png_snprintf.
Added log option to pngvalid.c and attempted to improve gamma messages.
Version 1.5.3 [omitted]
People found the presence of a beta release following an rc release
to be confusing; therefore we bump the version to libpng-1.5.4beta01
and there will be no libpng-1.5.3 release.
Version 1.5.4beta01 [June 14, 2011]
Made it possible to undefine PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
to get the same (inaccurate) output as libpng-1.5.2 and earlier.
Moved definitions of PNG_HAVE_IHDR, PNG_AFTER_IDAT, and PNG_HAVE_PLTE
outside of an unknown-chunk block in png.h because they are also
needed for other uses.
Version 1.5.4beta02 [June 14, 2011]
Fixed and clarified LEGACY 16-to-8 scaling code.
Added png_set_chop_16() API, to match inaccurate results from previous
libpng versions.
Removed the ACCURATE and LEGACY options (they are no longer useable)
Use the old scaling method for background if png_set_chop_16() was
called.
Made png_set_chop_16() API removeable by disabling PNG_CHOP_16_TO_8_SUPPORTED
Version 1.5.4beta03 [June 15, 2011]
Fixed a problem in png_do_expand_palette() exposed by optimization in
1.5.3beta06
Also removed a spurious and confusing "trans" member ("trans") from png_info.
The palette expand optimization prevented expansion to an intermediate RGBA
form if tRNS was present but alpha was marked to be stripped; this exposed
a check for tRNS in png_do_expand_palette() which is inconsistent with the
code elsewhere in libpng.
Correction to the expand_16 code; removed extra instance of
png_set_scale_16_to_8 from pngpriv.h
Version 1.5.4beta04 [June 16, 2011]
Added a missing "#ifdef PNG_READ_BACKGROUND_SUPPORTED/#endif" in pngrtran.c
Added PNG_TRANSFORM_CHOP_16 to the high-level read transforms.
Made PNG_READ_16_TO_8_ACCURATE_SCALE configurable again. If this is
not enabled, png_set_strip_16() and png_do_scale_16_to_8() aren't built.
Revised contrib/visupng, gregbook, and pngminim to demonstrate chop_16_to_8
Version 1.5.4beta05 [June 16, 2011]
Renamed png_set_strip_16() to png_set_scale_16() and renamed
png_set_chop_16() to png_set_strip(16) in an attempt to minimize the
behavior changes between libpng14 and libpng15.
Version 1.5.4beta06 [June 18, 2011]
Fixed new bug that was causing both strip_16 and scale_16 to be applied.
Version 1.5.4beta07 [June 19, 2011]
Fixed pngvalid, simplified macros, added checking for 0 in sCAL.
The ACCURATE scale macro is no longer defined in 1.5 - call the
png_scale_16_to_8 API. Made sure that PNG_READ_16_TO_8 is still defined
if the png_strip_16_to_8 API is present. png_check_fp_number now
maintains some state so that positive, negative and zero values are
identified. sCAL uses these to be strictly spec conformant.
Version 1.5.4beta08 [June 23, 2011]
Fixed pngvalid if ACCURATE_SCALE is defined.
Updated scripts/pnglibconf.h.prebuilt.
Version 1.5.4rc01 [June 30, 2011]
Define PNG_ALLOCATED to "restrict" only if MSC_VER >= 1400.
Version 1.5.4 [July 7, 2011]
No changes.
Version 1.5.5beta01 [July 13, 2011]
Fixed some typos and made other minor changes in the manual.
Updated contrib/pngminus/makefile.std (Samuli Souminen)
Version 1.5.5beta02 [July 14, 2011]
Revised Makefile.am and Makefile.in to look in the right directory for
pnglibconf.h.prebuilt
Version 1.5.5beta03 [July 27, 2011]
Enabled compilation with g++ compiler. This compiler does not recognize
the file extension, so it always compiles with C++ rules. Made minor
changes to pngrutil.c to cast results where C++ expects it but C does not.
Minor editing of libpng.3 and libpng-manual.txt.
Version 1.5.5beta04 [July 29, 2011]
Revised CMakeLists.txt (Clifford Yapp)
Updated commentary about the png_rgb_to_gray() default coefficients
in the manual and in pngrtran.c
Version 1.5.5beta05 [August 17, 2011]
Prevent unexpected API exports from non-libpng DLLs on Windows. The "_DLL"
is removed from the test of whether a DLL is being built (this erroneously
caused the libpng APIs to be marked as DLL exports in static builds under
Microsoft Visual Studio). Almost all of the libpng building configuration
is moved from pngconf.h to pngpriv.h, but PNG_DLL_EXPORT remains in
pngconf.h, though, so that it is colocated with the import definition (it
is no longer used anywhere in the installed headers). The VStudio project
definitions have been cleaned up: "_USRDLL" has been removed from the
static library builds (this was incorrect), and PNG_USE_DLL has been added
to pngvalid to test the functionality (pngtest does not supply it,
deliberately). The spurious "_EXPORTS" has been removed from the
libpng build (all these errors were a result of copy/paste between project
configurations.)
Added new types and internal functions for CIE RGB end point handling to
pngpriv.h (functions yet to be implemented).
Version 1.5.5beta06 [August 26, 2011]
Ensure the CMAKE_LIBRARY_OUTPUT_DIRECTORY is set in CMakeLists.txt
(Clifford Yap)
Fixes to rgb_to_gray and cHRM XYZ APIs (John Bowler):
The rgb_to_gray code had errors when combined with gamma correction.
Some pixels were treated as true grey when they weren't and such pixels
and true grey ones were not gamma corrected (the original value of the
red component was used instead). APIs to get and set cHRM using color
space end points have been added and the rgb_to_gray code that defaults
based on cHRM, and the divide-by-zero bug in png_handle_cHRM (CERT
VU#477046, CVE-2011-3328, introduced in 1.5.4) have been corrected.
A considerable number of tests has been added to pngvalid for the
rgb_to_gray transform.
Arithmetic errors in rgb_to_gray whereby the calculated gray value was
truncated to the bit depth rather than rounded have been fixed except in
the 8-bit non-gamma-corrected case (where consistency seems more important
than correctness.) The code still has considerable inaccuracies in the
8-bit case because 8-bit linear arithmetic is used.
Version 1.5.5beta07 [September 7, 2011]
Added "$(ARCH)" option to makefile.darwin
Added SunOS support to configure.ac and Makefile.am
Changed png_chunk_benign_error() to png_warning() in png.c, in
png_XYZ_from_xy_checked().
Version 1.5.5beta08 [September 10, 2011]
Fixed 64-bit compilation errors (gcc). The errors fixed relate
to conditions where types that are 32 bits in the GCC 32-bit
world (uLong and png_size_t) become 64 bits in the 64-bit
world. This produces potential truncation errors which the
compiler correctly flags.
Relocated new HAVE_SOLARIS_LD definition in configure.ac
Constant changes for 64-bit compatibility (removal of L suffixes). The
16-bit cases still use "L" as we don't have a 16-bit test system.
Version 1.5.5rc01 [September 15, 2011]
Removed "L" suffixes in pngpriv.h
Version 1.5.5 [September 22, 2011]
No changes.
Version 1.5.6beta01 [September 22, 2011]
Fixed some 64-bit type conversion warnings in pngrtran.c
Moved row_info from png_struct to a local variable.
The various interlace mask arrays have been made into arrays of
bytes and made PNG_CONST and static (previously some arrays were
marked PNG_CONST and some weren't).
Additional checks have been added to the transform code to validate the
pixel depths after the transforms on both read and write.
Removed some redundant code from pngwrite.c, in png_destroy_write_struct().
Changed chunk reading/writing code to use png_uint_32 instead of png_byte[4].
This removes the need to allocate temporary strings for chunk names on
the stack in the read/write code. Unknown chunk handling still uses the
string form because this is exposed in the API.
Version 1.5.6beta02 [September 26, 2011]
Added a note in the manual the png_read_update_info() must be called only
once with a particular info_ptr.
Fixed a typo in the definition of the new PNG_STRING_FROM_CHUNK(s,c) macro.
Version 1.5.6beta03 [September 28, 2011]
Revised test-pngtest.sh to report FAIL when pngtest fails.
Added "--strict" option to pngtest, to report FAIL when the failure is
only because the resulting valid files are different.
Revised CMakeLists.txt to work with mingw and removed some material from
CMakeLists.txt that is no longer useful in libpng-1.5.
Version 1.5.6beta04 [October 5, 2011]
Fixed typo in Makefile.in and Makefile.am ("-M Wl" should be "-M -Wl")."
Version 1.5.6beta05 [October 12, 2011]
Speed up png_combine_row() for interlaced images. This reduces the generality
of the code, allowing it to be optimized for Adam7 interlace. The masks
passed to png_combine_row() are now generated internally, avoiding
some code duplication and localizing the interlace handling somewhat.
Align png_struct::row_buf - previously it was always unaligned, caused by
a bug in the code that attempted to align it; the code needs to subtract
one from the pointer to take account of the filter byte prepended to
each row.
Optimized png_combine_row() when rows are aligned. This gains a small
percentage for 16-bit and 32-bit pixels in the typical case where the
output row buffers are appropriately aligned. The optimization was not
previously possible because the png_struct buffer was always misaligned.
Fixed bug in png_write_chunk_header() debug print, introduced in 1.5.6beta01.
Version 1.5.6beta06 [October 17, 2011]
Removed two redundant tests for unitialized row.
Fixed a relatively harmless memory overwrite in compressed text writing
with a 1 byte zlib buffer.
Add ability to call png_read_update_info multiple times to pngvalid.c.
Fixes for multiple calls to png_read_update_info. These fixes attend to
most of the errors revealed in pngvalid, however doing the gamma work
twice results in inaccuracies that can't be easily fixed. There is now
a warning in the code if this is going to happen.
Turned on multiple png_read_update_info in pngvalid transform tests.
Prevent libpng from overwriting unused bits at the end of the image when
it is not byte aligned, while reading. Prior to libpng-1.5.6 libpng would
overwrite the partial byte at the end of each row if the row width was not
an exact multiple of 8 bits and the image is not interlaced.
Version 1.5.6beta07 [October 21, 2011]
Made png_ptr->prev_row an aligned pointer into png_ptr->big_prev_row
(Mans Rullgard).
Version 1.5.6rc01 [October 26, 2011]
Changed misleading "Missing PLTE before cHRM" warning to "Out of place cHRM"
Version 1.5.6rc02 [October 27, 2011]
Added LSR() macro to defend against buggy compilers that evaluate non-taken
code branches and complain about out-of-range shifts.
Version 1.5.6rc03 [October 28, 2011]
Renamed the LSR() macro to PNG_LSR() and added PNG_LSL() macro.
Fixed compiler warnings with Intel and MSYS compilers. The logical shift
fix for Microsoft Visual C is required by other compilers, so this
enables that fix for all compilers when using compile-time constants.
Under MSYS 'byte' is a name declared in a system header file, so we
changed the name of a local variable to avoid the warnings that result.
Added #define PNG_ALIGN_TYPE PNG_ALIGN_NONE to contrib/pngminim/*/pngusr.h
Version 1.5.6 [November 3, 2011]
No changes.
Version 1.5.7beta01 [November 4, 2011]
Added support for ARM processor, when decoding all PNG up-filtered rows
and any other-filtered rows with 3 or 4 bytes per pixel (Mans Rullgard).
Fixed bug in pngvalid on early allocation failure; fixed type cast in
pngmem.c; pngvalid would attempt to call png_error() if the allocation
of a png_struct or png_info failed. This would probably have led to a
crash. The pngmem.c implementation of png_malloc() included a cast
to png_size_t which would fail on large allocations on 16-bit systems.
Fix for the preprocessor of the Intel C compiler. The preprocessor
splits adjacent @ signs with a space; this changes the concatentation
token from @-@-@ to PNG_JOIN; that should work with all compiler
preprocessors.
Paeth filter speed improvements from work by Siarhei Siamashka. This
changes the 'Paeth' reconstruction function to improve the GCC code
generation on x86. The changes are only part of the suggested ones;
just the changes that definitely improve speed and remain simple.
The changes also slightly increase the clarity of the code.
Version 1.5.7beta02 [November 11, 2011]
Check compression_type parameter in png_get_iCCP and remove spurious
casts. The compression_type parameter is always assigned to, so must
be non-NULL. The cast of the profile length potentially truncated the
value unnecessarily on a 16-bit int system, so the cast of the (byte)
compression type to (int) is specified by ANSI-C anyway.
Fixed FP division by zero in pngvalid.c; the 'test_pixel' code left
the sBIT fields in the test pixel as 0, which resulted in a floating
point division by zero which was irrelevant but causes systems where
FP exceptions cause a crash. Added code to pngvalid to turn on FP
exceptions if the appropriate glibc support is there to ensure this is
tested in the future.
Updated scripts/pnglibconf.mak and scripts/makefile.std to handle the
new PNG_JOIN macro.
Added versioning to pnglibconf.h comments.
Simplified read/write API initial version; basic read/write tested on
a variety of images, limited documentation (in the header file.)
Installed more accurate linear to sRGB conversion tables. The slightly
modified tables reduce the number of 16-bit values that
convert to an off-by-one 8-bit value. The "makesRGB.c" code that was used
to generate the tables is now in a contrib/sRGBtables sub-directory.
Version 1.5.7beta03 [November 17, 2011]
Removed PNG_CONST from the sRGB table declarations in pngpriv.h and png.c
Added run-time detection of NEON support.
Added contrib/libtests; includes simplified API test and timing test and
a color conversion utility for rapid checking of failed 'pngstest' results.
Multiple transform bug fixes plus a work-round for double gamma correction.
libpng does not support more than one transform that requires linear data
at once - if this is tried typically the results is double gamma
correction. Since the simplified APIs can need rgb to gray combined with
a compose operation it is necessary to do one of these outside the main
libpng transform code. This check-in also contains fixes to various bugs
in the simplified APIs themselves and to some bugs in compose and rgb to
gray (on palette) itself.
Fixes for C++ compilation using g++ When libpng source is compiled
using g++. The compiler imposes C++ rules on the C source; thus it
is desireable to make the source work with either C or C++ rules
without throwing away useful error information. This change adds
png_voidcast to allow C semantic (void*) cases or the corresponding
C++ static_cast operation, as appropriate.
Added --noexecstack to assembler file compilation. GCC does not set
this on assembler compilation, even though it does on C compilation.
This creates security issues if assembler code is enabled; the
work-around is to set it by default in the flags for $(CCAS)
Work around compilers that don't support declaration of const data. Some
compilers fault 'extern const' data declarations (because the data is
not initialized); this turns on const-ness only for compilers where
this is known to work.
Version 1.5.7beta04 [November 17, 2011]
Since the gcc driver does not recognize the --noexecstack flag, we must
use the -Wa prefix to have it passed through to the assembler.
Also removed a duplicate setting of this flag.
Added files that were omitted from the libpng-1.5.7beta03 zip distribution.
Version 1.5.7beta05 [November 25, 2011]
Removed "zTXt" from warning in generic chunk decompression function.
Validate time settings passed to pngset() and png_convert_to_rfc1123()
(Frank Busse).
Added MINGW support to CMakeLists.txt
Reject invalid compression flag or method when reading the iTXt chunk.
Backed out 'simplified' API changes. The API seems too complex and there
is a lack of consensus or enthusiasm for the proposals. The API also
reveals significant bugs inside libpng (double gamma correction and the
known bug of being unable to retrieve a corrected palette). It seems
better to wait until the bugs, at least, are corrected.
Moved pngvalid.c into contrib/libtests
Rebuilt Makefile.in, configure, etc., with autoconf-2.68
Version 1.5.7rc01 [December 1, 2011]
Replaced an "#if" with "#ifdef" in pngrtran.c
Revised #if PNG_DO_BC block in png.c (use #ifdef and add #else)
Version 1.5.7rc02 [December 5, 2011]
Revised project files and contrib/pngvalid/pngvalid.c to account for
the relocation of pngvalid into contrib/libtests.
Revised pngconf.h to use " __declspec(restrict)" only when MSC_VER >= 1400,
as in libpng-1.5.4.
Put CRLF line endings in the owatcom project files.
Version 1.5.7rc03 [December 7, 2011]
Updated CMakeLists.txt to account for the relocation of pngvalid.c
Version 1.5.7 [December 15, 2011]
Minor fixes to pngvalid.c for gcc 4.6.2 compatibility to remove warnings
reported by earlier versions.
Fixed minor memset/sizeof errors in pngvalid.c.
Version 1.6.0beta01 [December 15, 2011]
Removed machine-generated configure files from the GIT repository (they will
continue to appear in the tarball distributions and in the libpng15 and
earlier GIT branches).
Restored the new 'simplified' API, which was started in libpng-1.5.7beta02
but later deleted from libpng-1.5.7beta05.
Added example programs for the new 'simplified' API.
Added ANSI-C (C90) headers and require them, and take advantage of the
change. Also fixed some of the projects/* and contrib/* files that needed
updates for libpng16 and the move of pngvalid.c.
With this change the required ANSI-C header files are assumed to exist: the
implementation must provide float.h, limits.h, stdarg.h and stddef.h and
libpng relies on limits.h and stddef.h existing and behaving as defined
(the other two required headers aren't used). Non-ANSI systems that don't
have stddef.h or limits.h will have to provide an appropriate fake
containing the relevant types and #defines.
The use of FAR/far has been eliminated and the definition of png_alloc_size_t
is now controlled by a flag so that 'small size_t' systems can select it
if necessary. Libpng 1.6 may not currently work on such systems -- it
seems likely that it will ask 'malloc' for more than 65535 bytes with any
image that has a sufficiently large row size (rather than simply failing
to read such images).
New tools directory containing tools used to generate libpng code.
Fixed race conditions in parallel make builds. With higher degrees of
parallelism during 'make' the use of the same temporary file names such
as 'dfn*' can result in a race where a temporary file from one arm of the
build is deleted or overwritten in another arm. This changes the
temporary files for suffix rules to always use $* and ensures that the
non-suffix rules use unique file names.
Version 1.6.0beta02 [December 21, 2011]
Correct configure builds where build and source directories are separate.
The include path of 'config.h' was erroneously made relative in pngvalid.c
in libpng 1.5.7.
Version 1.6.0beta03 [December 22, 2011]
Start-up code size improvements, error handler flexibility. These changes
alter how the tricky allocation of the initial png_struct and png_info
structures are handled. png_info is now handled in pretty much the same
way as everything else, except that the allocations handle NULL return
silently. png_struct is changed in a similar way on allocation and on
deallocation a 'safety' error handler is put in place (which should never
be required). The error handler itself is changed to permit mismatches
in the application and libpng error buffer size; however, this means a
silent change to the API to return the jmp_buf if the size doesn't match
the size from the libpng compilation; libpng now allocates the memory and
this may fail. Overall these changes result in slight code size
reductions; however, this is a reduction in code that is always executed
so is particularly valuable. Overall on a 64-bit system the libpng DLL
decreases in code size by 1733 bytes. pngerror.o increases in size by
about 465 bytes because of the new functionality.
Added png_convert_to_rfc1123_buffer() and deprecated png_convert_to_rfc1123()
to avoid including a spurious buffer in the png_struct.
Version 1.6.0beta04 [December 30, 2011]
Regenerated configure scripts with automake-1.11.2
Eliminated png_info_destroy(). It is now used only in png.c and only calls
one other internal function and memset().
Enabled png_get_sCAL_fixed() if floating point APIs are enabled. Previously
it was disabled whenever internal fixed point arithmetic was selected,
which meant it didn't exist even on systems where FP was available but not
preferred.
Added pngvalid.c compile time checks for const APIs.
Implemented 'restrict' for png_info and png_struct. Because of the way
libpng works both png_info and png_struct are always accessed via a
single pointer. This means adding C99 'restrict' to the pointer gives
the compiler some opportunity to optimize the code. This change allows
that.
Moved AC_MSG_CHECKING([if libraries can be versioned]) later to the proper
location in configure.ac (Gilles Espinasse).
Changed png_memcpy to C assignment where appropriate. Changed all those
uses of png_memcpy that were doing a simple assignment to assignments
(all those cases where the thing being copied is a non-array C L-value).
Added some error checking to png_set_*() routines.
Removed the reference to the non-exported function png_memcpy() from
example.c.
Fixed the Visual C 64-bit build - it requires jmp_buf to be aligned, but
it had become misaligned.
Revised contrib/pngminus/pnm2png.c to avoid warnings when png_uint_32
and unsigned long are of different sizes.
Version 1.6.0beta05 [January 15, 2012]
Updated manual with description of the simplified API (copied from png.h)
Fix bug in pngerror.c: some long warnings were being improperly truncated
(CVE-2011-3464, bug introduced in libpng-1.5.3beta05).
Version 1.6.0beta06 [January 24, 2012]
Added palette support to the simplified APIs. This commit
changes some of the macro definitions in png.h, app code
may need corresponding changes.
Increased the formatted warning buffer to 192 bytes.
Added color-map support to simplified API. This is an initial version for
review; the documentation has not yet been updated.
Fixed Min/GW uninstall to remove libpng.dll.a
Version 1.6.0beta07 [January 28, 2012]
Eliminated Intel icc/icl compiler warnings. The Intel (GCC derived)
compiler issues slightly different warnings from those issued by the
current vesions of GCC. This eliminates those warnings by
adding/removing casts and small code rewrites.
Updated configure.ac from autoupdate: added --enable-werror option.
Also some layout regularization and removal of introduced tab characters
(replaced with 3-character indentation). Obsolete macros identified by
autoupdate have been removed; the replacements are all in 2.59 so
the pre-req hasn't been changed. --enable-werror checks for support
for -Werror (or the given argument) in the compiler. This mimics the
gcc configure option by allowing -Werror to be turned on safely; without
the option the tests written in configure itself fail compilation because
they cause compiler warnings.
Rewrote autogen.sh to run autoreconf instead of running tools one-by-one.
Conditionalize the install rules for MINGW and CYGWIN in CMakeLists.txt and
set CMAKE_LIBRARY_OUTPUT_DIRECTORY to "lib" on all platforms (C. Yapp).
Freeze libtool files in the 'scripts' directory. This version of autogen.sh
attempts to dissuade people from running it when it is not, or should not,
be necessary. In fact, autogen.sh does not work when run in a libpng
directory extracted from a tar distribution anymore. You must run it in
a GIT clone instead.
Added two images to contrib/pngsuite (1-bit and 2-bit transparent grayscale),
and renamed three whose names were inconsistent with those in
pngsuite/README.txt.
Version 1.6.0beta08 [February 1, 2012]
Fixed Image::colormap misalignment in pngstest.c
Check libtool/libtoolize version number (2.4.2) in configure.ac
Divide test-pngstest.sh into separate pngstest runs for basic and
transparent images.
Moved automake options to AM_INIT_AUTOMAKE in configure.ac
Added color-tests, silent-rules (Not yet implemented in Makefile.am) and
version checking to configure.ac
Improved pngstest speed by not doing redundant tests and add const to
the background parameter of png_image_finish_read. The --background
option is now done automagically only when required, so that commandline
option no longer exists.
Cleaned up pngpriv.h to consistently declare all functions and data.
Also eliminated PNG_CONST_DATA, which is apparently not needed but we
can't be sure until it is gone.
Added symbol prefixing that allows all the libpng external symbols
to be prefixed (suggested by Reuben Hawkins).
Updated "ftbb*.png" list in the owatcom and vstudio projects.
Fixed 'prefix' builds on clean systems. The generation of pngprefix.h
should not require itself.
Updated INSTALL to explain that autogen.sh must be run in a GIT clone,
not in a libpng directory extracted from a tar distribution.
Version 1.6.0beta09 [February 1, 2012]
Reverted the prebuilt configure files to libpng-1.6.0beta05 condition.
Version 1.6.0beta10 [February 3, 2012]
Added Z_SOLO for zlib-1.2.6+ and correct pngstest tests
Updated list of test images in CMakeLists.txt
Updated the prebuilt configure files to current condition.
Revised INSTALL information about autogen.sh; it works in tar distributions.
Version 1.6.0beta11 [February 16, 2012]
Fix character count in pngstest command in projects/owatcom/pngstest.tgt
Revised test-pngstest.sh to report PASS/FAIL for each image.
Updated documentation about the simplified API.
Corrected estimate of error in libpng png_set_rgb_to_gray API. The API is
extremely inaccurate for sRGB conversions because it uses an 8-bit
intermediate linear value and it does not use the sRGB transform, so it
suffers from the known instability in gamma transforms for values close
to 0 (see Poynton). The net result is that the calculation has a maximum
error of 14.99/255; 0.5/255^(1/2.2). pngstest now uses 15 for the
permitted 8-bit error. This may still not be enough because of arithmetic
error.
Removed some unused arrays (with #ifdef) from png_read_push_finish_row().
Fixed a memory overwrite bug in simplified read of RGB PNG with
non-linear gamma Also bugs in the error checking in pngread.c and changed
quite a lot of the checks in pngstest.c to be correct; either correctly
written or not over-optimistic. The pngstest changes are insufficient to
allow all possible RGB transforms to be passed; pngstest cmppixel needs
to be rewritten to make it clearer which errors it allows and then changed
to permit known inaccuracies.
Removed tests for no-longer-used *_EMPTY_PLTE_SUPPORTED from pngstruct.h
Fixed fixed/float API export conditionals. 1) If FIXED_POINT or
FLOATING_POINT options were switched off, png.h ended up with lone ';'
characters. This is not valid ANSI-C outside a function. The ';'
characters have been moved inside the definition of PNG_FP_EXPORT and
PNG_FIXED_EXPORT. 2) If either option was switched off, the declaration
of the corresponding functions were completely omitted, even though some
of them are still used internally. The result is still valid, but
produces warnings from gcc with some warning options (including -Wall). The
fix is to cause png.h to declare the functions with PNG_INTERNAL_FUNCTION
when png.h is included from pngpriv.h.
Check for invalid palette index while reading paletted PNG. When one is
found, issue a warning and increase png_ptr->num_palette accordingly.
Apps are responsible for checking to see if that happened.
Version 1.6.0beta12 [February 18, 2012]
Do not increase num_palette on invalid_index.
Relocated check for invalid palette index to pngrtran.c, after unpacking
the sub-8-bit pixels.
Fixed CVE-2011-3026 buffer overrun bug. This bug was introduced when
iCCP chunk support was added at libpng-1.0.6. Deal more correctly with the
test on iCCP chunk length. Also removed spurious casts that may hide
problems on 16-bit systems.
Version 1.6.0beta13 [February 24, 2012]
Eliminated redundant png_push_read_tEXt|zTXt|iTXt|unknown code from
pngpread.c and use the sequential png_handle_tEXt, etc., in pngrutil.c;
now that png_ptr->buffer is inaccessible to applications, the special
handling is no longer useful.
Added PNG_SAFE_LIMITS feature to pnglibconf.dfa, pngpriv.h, and new
pngusr.dfa to reset the user limits to safe ones if PNG_SAFE_LIMITS is
defined. To enable, use "CPPFLAGS=-DPNG_SAFE_LIMITS_SUPPORTED=1" on the
configure command or put #define PNG_SAFE_LIMITS_SUPPORTED in
pnglibconf.h.prebuilt and pnglibconf.h.
Version 1.6.0beta14 [February 27, 2012]
Added information about the new limits in the manual.
Updated Makefile.in
Version 1.6.0beta15 [March 2, 2012]
Removed unused "current_text" members of png_struct and the png_free()
of png_ptr->current_text from pngread.c
Rewrote pngstest.c for substantial speed improvement.
Fixed transparent pixel and 16-bit rgb tests in pngstest and removed a
spurious check in pngwrite.c
Added PNG_IMAGE_FLAG_FAST for the benefit of applications that store
intermediate files, or intermediate in-memory data, while processing
image data with the simplified API. The option makes the files larger
but faster to write and read. pngstest now uses this by default; this
can be disabled with the --slow option.
Improved pngstest fine tuning of error numbers, new test file generator.
The generator generates images that test the full range of sample values,
allow the error numbers in pngstest to be tuned and checked. makepng
also allows generation of images with extra chunks, although this is
still work-in-progress.
Added check for invalid palette index while reading.
Fixed some bugs in ICC profile writing. The code should now accept
all potentially valid ICC profiles and reject obviously invalid ones.
It now uses png_error() to do so rather than casually writing a PNG
without the necessary color data.
Removed whitespace from the end of lines in all source files and scripts.
Version 1.6.0beta16 [March 6, 2012]
Relocated palette-index checking function from pngrutil.c to pngtrans.c
Added palette-index checking while writing.
Changed png_inflate() and calling routines to avoid overflow problems.
This is an intermediate check-in that solves the immediate problems and
introduces one performance improvement (avoiding a copy via png_ptr->zbuf.)
Further changes will be made to make ICC profile handling more secure.
Fixed build warnings (MSVC, GCC, GCC v3). Cygwin GCC with default options
declares 'index' as a global, causing a warning if it is used as a local
variable. GCC 64-bit warns about assigning a (size_t) (unsigned 64-bit)
to an (int) (signed 32-bit). MSVC, however, warns about using the
unary '-' operator on an unsigned value (even though it is well defined
by ANSI-C to be ~x+1). The padding calculation was changed to use a
different method. Removed the tests on png_ptr->pass.
Added contrib/libtests/tarith.c to test internal arithmetic functions from
png.c. This is a libpng maintainer program used to validate changes to the
internal arithmetic functions.
Made read 'inflate' handling like write 'deflate' handling. The read
code now claims and releases png_ptr->zstream, like the write code.
The bug whereby the progressive reader failed to release the zstream
is now fixed, all initialization is delayed, and the code checks for
changed parameters on deflate rather than always calling
deflatedEnd/deflateInit.
Validate the zTXt strings in pngvalid.
Added code to validate the windowBits value passed to deflateInit2().
If the call to deflateInit2() is wrong a png_warning will be issued
(in fact this is harmless, but the PNG data produced may be sub-optimal).
Version 1.6.0beta17 [March 10, 2012]
Fixed PNG_LIBPNG_BUILD_BASE_TYPE definition.
Reject all iCCP chunks after the first, even if the first one is invalid.
Deflate/inflate was reworked to move common zlib calls into single
functions [rw]util.c. A new shared keyword check routine was also added
and the 'zbuf' is no longer allocated on progressive read. It is now
possible to call png_inflate() incrementally. A warning is no longer
issued if the language tag or translated keyword in the iTXt chunk
has zero length.
If benign errors are disabled use maximum window on ancilliary inflate.
This works round a bug introduced in 1.5.4 where compressed ancillary
chunks could end up with a too-small windowBits value in the deflate
header.
Version 1.6.0beta18 [March 16, 2012]
Issue a png_benign_error() instead of png_warning() about bad palette index.
In pngtest, treat benign errors as errors if "-strict" is present.
Fixed an off-by-one error in the palette index checking function.
Fixed a compiler warning under Cygwin (Windows-7, 32-bit system)
Revised example.c to put text strings in a temporary character array
instead of directly assigning string constants to png_textp members.
This avoids compiler warnings when -Wwrite-strings is enabled.
Added output flushing to aid debugging under Visual Studio. Unfortunately
this is necessary because the VS2010 output window otherwise simply loses
the error messages on error (they weren't flushed to the window before
the process exited, apparently!)
Added configuration support for benign errors and changed the read
default. Also changed some warnings in the iCCP and sRGB handling
from to benign errors. Configuration now makes read benign
errors warnings and write benign errors to errors by default (thus
changing the behavior on read). The simplified API always forces
read benign errors to warnings (regardless of the system default, unless
this is disabled in which case the simplified API can't be built.)
Version 1.6.0beta19 [March 18, 2012]
Work around for duplicate row start calls; added warning messages.
This turns on PNG_FLAG_DETECT_UNINITIALIZED to detect app code that
fails to call one of the 'start' routines (not enabled in libpng-1.5
because it is technically an API change, since it did normally work
before.) It also makes duplicate calls to png_read_start_row (an
internal function called at the start of the image read) benign, as
they were before changes to use png_inflate_claim. Somehow webkit is
causing this to happen; this is probably a mis-feature in the zlib
changes so this commit is only a work-round.
Removed erroneous setting of DETECT_UNINITIALIZED and added more
checks. The code now does a png_error if an attempt is made to do the
row initialization twice; this is an application error and it has
serious consequences because the transform data in png_struct is
changed by each call.
Added application error reporting and added chunk names to read
benign errors; also added --strict to pngstest - not enabled
yet because a warning is produced.
Avoid the double gamma correction warning in the simplified API.
This allows the --strict option to pass in the pngstest checks
Version 1.6.0beta20 [March 29, 2012]
Changed chunk handler warnings into benign errors, incrementally load iCCP
Added checksum-icc.c to contrib/tools
Prevent PNG_EXPAND+PNG_SHIFT doing the shift twice.
Recognize known sRGB ICC profiles while reading; prefer writing the
iCCP profile over writing the sRGB chunk, controlled by the
PNG_sRGB_PROFILE_CHECKS option.
Revised png_set_text_2() to avoid potential memory corruption (fixes
CVE-2011-3048, also known as CVE-2012-3425).
Version 1.6.0beta21 [April 27, 2012]
Revised scripts/makefile.darwin: use system zlib; remove quotes around
architecture list; add missing ppc architecture; add architecture options
to shared library link; don't try to create a shared lib based on missing
RELEASE variable.
Enable png_set_check_for_invalid_index() for both read and write.
Removed #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED in pngpriv.h around
declaration of png_handle_unknown().
Added -lssp_nonshared in a comment in scripts/makefile.freebsd
and changed deprecated NOOBJ and NOPROFILE to NO_OBJ and NO_PROFILE.
Version 1.6.0beta22 [May 23, 2012]
Removed need for -Wno-cast-align with clang. clang correctly warns on
alignment increasing pointer casts when -Wcast-align is passed. This
fixes the cases that clang warns about either by eliminating the
casts from png_bytep to png_uint_16p (pngread.c), or, for pngrutil.c
where the cast is previously verified or pngstest.c where it is OK, by
introducing new png_aligncast macros to do the cast in a way that clang
accepts.
Version 1.6.0beta23 [June 6, 2012]
Revised CMakeLists.txt to not attempt to make a symlink under mingw.
Made fixes for new optimization warnings from gcc 4.7.0. The compiler
performs an optimization which is safe; however it then warns about it.
Changing the type of 'palette_number' in pngvalid.c removes the warning.
Do not depend upon a GCC feature macro being available for use in generating
the linker mapfile symbol prefix.
Improved performance of new do_check_palette_indexes() function (only
update the value when it actually increases, move test for whether
the check is wanted out of the function.
Version 1.6.0beta24 [June 7, 2012]
Don't check palette indexes if num_palette is 0 (as it can be in MNG files).
Version 1.6.0beta25 [June 16, 2012]
Revised png_set_keep_unknown_chunks() so num_chunks < 0 means ignore all
unknown chunks and all known chunks except for IHDR, PLTE, tRNS, IDAT,
and IEND. Previously it only meant ignore all unknown chunks, the
same as num_chunks == 0. Revised png_image_skip_unused_chunks() to
provide a list of chunks to be processed instead of a list of chunks to
ignore. Revised contrib/gregbook/readpng2.c accordingly.
Version 1.6.0beta26 [July 10, 2012]
Removed scripts/makefile.cegcc from the *.zip and *.7z distributions; it
depends on configure, which is not included in those archives.
Moved scripts/chkfmt to contrib/tools.
Changed "a+w" to "u+w" in Makefile.in to fix CVE-2012-3386.
Version 1.6.0beta27 [August 11, 2012]
Do not compile PNG_DEPRECATED, PNG_ALLOC and PNG_PRIVATE when __GNUC__ < 3.
Do not use __restrict when GNUC is <= 3.1
Removed references to png_zalloc() and png_zfree() from the manual.
Fixed configurations where floating point is completely disabled. Because
of the changes to support symbol prefixing PNG_INTERNAL_FUNCTION declares
floating point APIs during libpng builds even if they are completely
disabled. This requires the png floating point types (png_double*) to be
declared even though the functions are never actually defined. This
change provides a dummy definition so that the declarations work, yet any
implementation will fail to compile because of an incomplete type.
Re-eliminated the use of strcpy() in pngtest.c. An unncessary use of
strcpy() was accidentally re-introduced in libpng16; this change replaces
it with strncpy().
Eliminated use of png_sizeof(); use sizeof() instead.
Use a consistent style for (sizeof type) and (sizeof (array))
Cleanup of png_set_filler(). This function does very different things on
read and write. In libpng 1.6 the two cases can be distinguished and
considerable code cleanup, and extra error checking, is possible. This
makes calls on the write side that have no effect be ignored with a
png_app_error(), which can be disabled in the app using
png_set_benign_errors(), and removes the spurious use of usr_channels
on the read side.
Insist on autotools 1.12.1 for git builds because there are security issues
with 1.12 and insisting on anything less would allow 1.12 to be used.
Removed info_ptr->signature[8] from WRITE-only builds.
Add some conditions for compiling png_fixed(). This is a small function
but it requires "-lm" on some platforms.
Cause pngtest --strict to fail on any warning from libpng (not just errors)
and cause it not to fail at the comparison step if libpng lacks support
for writing chunks that it reads from the input (currently only implemented
for compressed text chunks).
Make all three "make check" test programs work without READ or WRITE support.
Now "make check" will succeed even if libpng is compiled with -DPNG_NO_READ
or -DPNG_NO_WRITE. The tests performed are reduced, but the basic reading
and writing of a PNG file is always tested by one or more of the tests.
Consistently use strlen(), memset(), memcpy(), and memcmp() instead of the
png_strlen(), png_memset(), png_memcpy(), and png_memcmp() macros.
Removed the png_sizeof(), png_strlen(), png_memset(), png_memcpy(), and
png_memcmp() macros.
Work around gcc 3.x and Microsoft Visual Studio 2010 complaints. Both object
to the split initialization of num_chunks.
Version 1.6.0beta28 [August 29, 2012]
Unknown handling fixes and clean up. This adds more correct option
control of the unknown handling, corrects the pre-existing bug where
the per-chunk 'keep' setting is ignored and makes it possible to skip
IDAT chunks in the sequential reader (broken in earlier 1.6 versions).
There is a new test program, test-unknown.c, which is a work in progress
(not currently part of the test suite). Comments in the header files now
explain how the unknown handling works.
Allow fine grain control of unknown chunk APIs. This change allows
png_set_keep_unknown_chunks() to be turned off if not required and causes
both read and write to behave appropriately (on read this is only possible
if the user callback is used to handle unknown chunks). The change
also removes the support for storing unknown chunks in the info_struct
if the only unknown handling enabled is via the callback, allowing libpng
to be configured with callback reading and none of the unnecessary code.
Corrected fix for unknown handling in pngtest. This reinstates the
libpng handling of unknown chunks other than vpAg and sTER (including
unsafe-to-copy chunks which were dropped before) and eliminates the
repositioning of vpAg and sTER in pngtest.png by changing pngtest.png
(so the chunks are where libpng would put them).
Added "tunknown" test and corrected a logic error in png_handle_unknown()
when SAVE support is absent. Moved the shell test scripts for
contrib/libtests from the libpng top directory to contrib/libtests.
png_handle_unknown() must always read or skip the chunk, if
SAVE_UNKNOWN_CHUNKS is turned off *and* the application does not set
a user callback an unknown chunk will not be read, leading to a read
error, which was revealed by the "tunknown" test.
Cleaned up and corrected ICC profile handling.
contrib/libtests/makepng: corrected 'rgb' and 'gray' cases. profile_error
messages could be truncated; made a correct buffer size calculation and
adjusted pngerror.c appropriately. png_icc_check_* checking improved;
changed the functions to receive the correct color type of the PNG on read
or write and check that it matches the color space of the profile (despite
what the comments said before, there is danger in assuming the app will
cope correctly with an RGB profile on a grayscale image and, since it
violates the PNG spec, allowing it is certain to produce inconsistent
app behavior and might even cause app crashes.) Check that profiles
contain the tags needed to process the PNG (tags all required by the ICC
spec). Removed unused PNG_STATIC from pngpriv.h.
Version 1.6.0beta29 [September 4, 2012]
Fixed the simplified API example programs to add the *colormap parameter
to several of he API and improved the error message if the version field
is not set.
Added contrib/examples/* to the *.zip and *.7z distributions.
Updated simplified API synopses and description of the png_image structure
in the manual.
Made makepng and pngtest produce identical PNGs, add "--relaxed" option
to pngtest. The "--relaxed" option turns off the benign errors that are
enabled by default in pre-RC builds. makepng can now write ICC profiles
where the length has not been extended to a multiple of 4, and pngtest
now intercepts all libpng errors, allowing the previously-introduced
"--strict test" on no warnings to actually work.
Improved ICC profile handling including cHRM chunk generation and fixed
Cygwin+MSVC build errors. The ICC profile handling now includes more
checking. Several errors that caused rejection of the profile are now
handled with a warning in such a way that the invalid profiles will be
read by default in release (but not pre-RC) builds but will not be
written by default. The easy part of handling the cHRM chunk is written,
where the ICC profile contains the required data. The more difficult
part plus guessing a gAMA value requires code to pass selected RGB values
through the profile.
Version 1.6.0beta30 [October 24, 2012]
Changed ICC profile matrix/vector types to not depend on array type rules.
By the ANSI-C standard the new types should be identical to the previous
versions, and all known versions of gcc tested with the previous versions
except for GCC-4.2.1 work with this version. The change makes the ANSI-C
rule that const applied to an array of elements applies instead to the
elements in the array moot by explicitly applying const to the base
elements of the png_icc_matrix and png_icc_vector types. The accidental
(harmless) 'const' previously applied to the parameters of two of the
functions have also been removed.
Added a work around for GCC 4.2 optimization bug.
Marked the broken (bad white point) original HP sRGB profiles correctly and
correct comments.
Added -DZ_SOLO to contrib/pngminim/*/makefile to work with zlib-1.2.7
Use /MDd for vstudio debug builds. Also added pngunkown to the vstudio
builds, fixed build errors and corrected a minor exit code error in
pngvalid if the 'touch' file name is invalid.
Add updated WARNING file to projects/vstudio from libpng 1.5/vstudio
Fixed build when using #define PNG_NO_READ_GAMMA in png_do_compose() in
pngrtran.c (Domani Hannes).
Version 1.6.0beta31 [November 1, 2012]
Undid the erroneous change to vstudio/pngvalid build in libpng-1.6.0beta30.
Made pngvalid so that it will build outside the libpng source tree.
Made builds -DPNG_NO_READ_GAMMA compile (the unit tests still fail).
Made PNG_NO_READ_GAMMA switch off interfaces that depend on READ_GAMMA.
Prior to 1.6.0 switching off READ_GAMMA did unpredictable things to the
interfaces that use it (specifically, png_do_background in 1.4 would
simply display composite for grayscale images but do composition
with the incorrect arithmetic for color ones). In 1.6 the semantic
of -DPNG_NO_READ_GAMMA is changed to simply disable any interface that
depends on it; this obliges people who set it to consider whether they
really want it off if they happen to use any of the interfaces in
question (typically most users who disable it won't).
Fixed GUIDs in projects/vstudio. Some were duplicated or missing,
resulting in VS2010 having to update the files.
Removed non-working ICC profile support code that was mostly added to
libpng-1.6.0beta29 and beta30. There was too much code for too little
gain; implementing full ICC color correction may be desireable but is left
up to applications.
Version 1.6.0beta32 [November 25, 2012]
Fixed an intermittent SEGV in pngstest due to an uninitialized array element.
Added the ability for contrib/libtests/makepng.c to make a PNG with just one
color. This is useful for debugging pngstest color inaccuracy reports.
Fixed error checking in the simplified write API (Olaf van der Spek)
Made png_user_version_check() ok to use with libpng version 1.10.x and later.
Version 1.6.0beta33 [December 15, 2012]
Fixed typo in png.c (PNG_SET_CHUNK_MALLOC_MAX should be PNG_CHUNK_MALLOC_MAX)
that causes the MALLOC_MAX limit not to work (John Bowler)
Change png_warning() to png_app_error() in pngwrite.c and comment the
fall-through condition.
Change png_warning() to png_app_warning() in png_write_tRNS().
Rearranged the ARM-NEON optimizations: Isolated the machine specific code
to the hardware subdirectory and added comments to pngrutil.c so that
implementors of other optimizations know what to do.
Fixed cases of unquoted DESTDIR in Makefile.am
Rebuilt Makefile.in, etc., with autoconf-2.69 and automake-1.12.5.
Version 1.6.0beta34 [December 19, 2012]
Cleaned up whitespace in the synopsis portion of the manpage "libpng.3"
Disassembled the version number in scripts/options.awk (necessary for
building on SunOs).
Version 1.6.0beta35 [December 23, 2012]
Made default Zlib compression settings be configurable. This adds #defines to
pnglibconf.h to control the defaults.
Fixed Windows build issues, enabled ARM compilation. Various warnings issued
by earlier versions of GCC fixed for Cygwin and Min/GW (which both use old
GCCs.) ARM support is enabled by default in zlib.props (unsupported by
Microsoft) and ARM compilation is made possible by deleting the check for
x86. The test programs cannot be run because they are not signed.
Version 1.6.0beta36 [January 2, 2013]
Discontinued distributing libpng-1.x.x.tar.bz2.
Discontinued distributing libpng-1.7.0-1.6.0-diff.txt and similar.
Rebuilt configure with autoconf-2.69 (inadvertently not done in beta33)
Fixed 'make distcheck' on SUN OS - libpng.so was not being removed
Version 1.6.0beta37 [January 10, 2013]
Fixed conceivable but difficult to repro overflow. Also added two test
programs to generate and test a PNG which should have the problem.
Version 1.6.0beta39 [January 19, 2013]
Again corrected attempt at overflow detection in png_set_unknown_chunks()
(CVE-2013-7353). Added overflow detection in png_set_sPLT() and
png_set_text_2() (CVE-2013-7354).
Version 1.6.0beta40 [January 20, 2013]
Use consistent handling of overflows in text, sPLT and unknown png_set_* APIs
Version 1.6.0rc01 [January 26, 2013]
No changes.
Version 1.6.0rc02 [February 4, 2013]
Added png_get_palette_max() function.
Version 1.6.0rc03 [February 5, 2013]
Fixed the png_get_palette_max API.
Version 1.6.0rc04 [February 7, 2013]
Turn serial tests back on (recently turned off by autotools upgrade).
Version 1.6.0rc05 [February 8, 2013]
Update manual about png_get_palette_max().
Version 1.6.0rc06 [February 9, 2013]
Fixed missing dependency in --prefix builds The intermediate
internal 'prefix.h' file can only be generated correctly after
pnglibconf.h, however the dependency was not in Makefile.am. The
symptoms are unpredictable depending on the order make chooses to
build pngprefix.h and pnglibconf.h, often the error goes unnoticed
because there is a system pnglibconf.h to use instead.
Version 1.6.0rc07 [February 10, 2013]
Enclosed the new png_get_palette_max in #ifdef PNG_GET_PALETTE_MAX_SUPPORTED
block, and revised pnglibconf.h and pnglibconf.h.prebuilt accordingly.
Version 1.6.0rc08 [February 10, 2013]
Fix typo in png.h #ifdef
Version 1.6.0 [February 14, 2013]
No changes.
Version 1.6.1beta01 [February 16, 2013]
Made symbol prefixing work with the ARM neon optimizations. Also allow
pngpriv.h to be included for preprocessor definitions only, so it can
be used in non-C/C++ files. Back ported from libpng 1.7.
Made sRGB check numbers consistent.
Ported libpng 1.5 options.awk/dfn file handling to 1.6, fixed one bug.
Removed cc -E workround, corrected png_get_palette_max API Tested on
SUN OS cc 5.9, which demonstrates the tokenization problem previously
avoided by using /lib/cpp. Since all .dfn output is now protected in
double quotes unless it is to be macro substituted the fix should
work everywhere.
Enabled parallel tests - back ported from libpng-1.7.
scripts/pnglibconf.dfa formatting improvements back ported from libpng17.
Fixed a race condition in the creation of the build 'scripts' directory
while building with a parallel make.
Use approved/supported Android method to check for NEON, use Linux/POSIX
1003.1 API to check /proc/self/auxv avoiding buffer allocation and other
library calls (ported from libpng15).
Version 1.6.1beta02 [February 19, 2013]
Use parentheses more consistently in "#if defined(MACRO)" tests.
Folded long lines.
Reenabled code to allow zero length PLTE chunks for MNG.
Version 1.6.1beta03 [February 22, 2013]
Fixed ALIGNED_MEMORY support.
Allow run-time ARM NEON checking to be disabled. A new configure option:
--enable-arm-neon=always will stop the run-time checks. New checks
src/Source/LibPNG/CHANGES view on Meta::CPAN
for it on then the build will fail if it can't be done.)
Updated the INSTALL document.
Version 1.6.1beta04 [February 27, 2013]
Revised INSTALL to recommend using CPPFLAGS instead of INCLUDES.
Revised scripts/makefile.freebsd to respect ZLIBLIB and ZLIBINC.
Revised scripts/dfn.awk to work with the buggy MSYS awk that has trouble
with CRLF line endings.
Version 1.6.1beta05 [March 1, 2013]
Avoid a possible memory leak in contrib/gregbook/readpng.c
Version 1.6.1beta06 [March 4, 2013]
Better documentation of unknown handling API interactions.
Corrected Android builds and corrected libpng.vers with symbol
prefixing. This adds an API to set optimization options externally,
providing an alternative and general solution for the non-portable
run-time tests used by the ARM Neon code. It also makes those tests
compile and link on Android.
The order of settings vs options in pnglibconf.h is reversed to allow
settings to depend on options and options can now set (or override) the
defaults for settings.
Version 1.6.1beta07 [March 7, 2013]
Corrected simplified API default gamma for color-mapped output, added
a flag to change default. In 1.6.0 when the simplified API was used
to produce color-mapped output from an input image with no gamma
information the gamma assumed for the input could be different from
that assumed for non-color-mapped output. In particular 16-bit depth
input files were assumed to be sRGB encoded, whereas in the 'direct'
case they were assumed to have linear data. This was an error. The
fix makes the simplified API treat all input files the same way and
adds a new flag to the png_image::flags member to allow the
application/user to specify that 16-bit files contain sRGB data
rather than the default linear.
Fixed bugs in the pngpixel and makepng test programs.
Version 1.6.1beta08 [March 7, 2013]
Fixed CMakelists.txt to allow building a single variant of the library
(Claudio Bley):
Introduced a PNG_LIB_TARGETS variable that lists all activated library
targets. It is an error if this variable ends up empty, ie. you have
to build at least one library variant.
Made the *_COPY targets only depend on library targets actually being build.
Use PNG_LIB_TARGETS to unify a code path.
Changed the CREATE_SYMLINK macro to expect the full path to a file as the
src/Source/LibPNG/CHANGES view on Meta::CPAN
Version 1.6.1 [March 28, 2013]
No changes.
Version 1.6.2beta01 [April 14, 2013]
Updated documentation of 1.5.x to 1.6.x changes in iCCP chunk handling.
Fixed incorrect warning of excess deflate data. End condition - the
warning would be produced if the end of the deflate stream wasn't read
in the last row. The warning is harmless.
Corrected the test on user transform changes on read. It was in the
png_set of the transform function, but that doesn't matter unless the
transform function changes the rowbuf size, and that is only valid if
transform_info is called.
Corrected a misplaced closing bracket in contrib/libtests/pngvalid.c
(Flavio Medeiros).
Corrected length written to uncompressed iTXt chunks (Samuli Suominen).
Bug was introduced in libpng-1.6.0.
Version 1.6.2rc01 [April 18, 2013]
Added contrib/tools/fixitxt.c, to repair the erroneous iTXt chunk length
written by libpng-1.6.0 and 1.6.1.
Disallow storing sRGB information when the sRGB is not supported.
Version 1.6.2rc02 [April 18, 2013]
Merge pngtest.c with libpng-1.7.0
Version 1.6.2rc03 [April 22, 2013]
Trivial spelling cleanup.
Version 1.6.2rc04 and 1.6.2rc05 [omitted]
Version 1.6.2rc06 [April 24, 2013]
Reverted to version 1.6.2rc03. Recent changes to arm/neon support
have been ported to libpng-1.7.0beta09 and will reappear in version
1.6.3beta01.
Version 1.6.2 [April 25, 2013]
No changes.
Version 1.6.3beta01 [April 25, 2013]
Revised stack marking in arm/filter_neon.S and configure.ac.
Ensure that NEON filter stuff is completely disabled when switched 'off'.
Previously the ARM NEON specific files were still built if the option
was switched 'off' as opposed to being explicitly disabled.
Version 1.6.3beta02 [April 26, 2013]
Test for 'arm*' not just 'arm' in the host_cpu configure variable.
Rebuilt the configure scripts.
Version 1.6.3beta03 [April 30, 2013]
Expanded manual paragraph about writing private chunks, particularly
the need to call png_set_keep_unknown_chunks() when writing them.
Avoid dereferencing NULL pointer possibly returned from
png_create_write_struct() (Andrew Church).
Version 1.6.3beta05 [May 9, 2013]
Calculate our own zlib windowBits when decoding rather than trusting the
CMF bytes in the PNG datastream.
Added an option to force maximum window size for inflating, which was
the behavior of libpng15 and earlier.
Added png-fix-itxt and png-fix-too-far-back to the built programs and
removed warnings from the source code and timepng that are revealed as
a result.
Detect wrong libpng versions linked to png-fix-too-far-back, which currently
only works with libpng versions that can be made to reliably fail when
the deflate data contains an out-of-window reference. This means only
1.6 and later.
Fixed gnu issues: g++ needs a static_cast, gcc 4.4.7 has a broken warning
message which it is easier to work round than ignore.
Updated contrib/pngminus/pnm2png.c (Paul Stewart):
Check for EOF
Ignore "#" delimited comments in input file to pnm2png.c.
Fixed whitespace handling
Added a call to png_set_packing()
Initialize dimension values so if sscanf fails at least we have known
invalid values.
Attempt to detect configuration issues with png-fix-too-far-back, which
requires both the correct libpng and the correct zlib to function
correctly.
Check ZLIB_VERNUM for mismatches, enclose #error in quotes
Added information in the documentation about problems with and fixes for
the bad CRC and bad iTXt chunk situations.
Version 1.6.3beta06 [May 12, 2013]
Allow contrib/pngminus/pnm2png.c to compile without WRITE_INVERT and
WRITE_PACK supported (writes error message that it can't read P1 or
P4 PBM files).
Improved png-fix-too-far-back usage message, added --suffix option.
Revised contrib/pngminim/*/makefile to generate pnglibconf.h with the
right zlib header files.
Separated CPPFLAGS and CFLAGS in contrib/pngminim/*/makefile
Version 1.6.3beta07 [June 8, 2013]
Removed a redundant test in png_set_IHDR().
Added set(CMAKE_CONFIGURATION_TYPES ...) to CMakeLists.txt (Andrew Hundt)
Deleted set(CMAKE_BUILD_TYPE) block from CMakeLists.txt
Enclose the prototypes for the simplified write API in
#ifdef PNG_STDIO_SUPPORTED/#endif
Make ARM NEON support work at compile time (not just configure time).
This moves the test on __ARM_NEON__ into pngconf.h to avoid issues when
using a compiler that compiles for multiple architectures at one time.
Removed PNG_FILTER_OPTIMIZATIONS and PNG_ARM_NEON_SUPPORTED from
pnglibconf.h, allowing more of the decisions to be made internally
(pngpriv.h) during the compile. Without this, symbol prefixing is broken
under certain circumstances on ARM platforms. Now only the API parts of
the optimizations ('check' vs 'api') are exposed in the public header files
except that the new setting PNG_ARM_NEON_OPT documents how libpng makes the
decision about whether or not to use the optimizations.
Protect symbol prefixing against CC/CPPFLAGS/CFLAGS useage.
Previous iOS/Xcode fixes for the ARM NEON optimizations moved the test
on __ARM_NEON__ from configure time to compile time. This breaks symbol
prefixing because the definition of the special png_init_filter_functions
call was hidden at configure time if the relevant compiler arguments are
passed in CFLAGS as opposed to CC. This change attempts to avoid all
the confusion that would result by declaring the init function even when
it is not used, so that it will always get prefixed.
Version 1.6.3beta08 [June 18, 2013]
Revised libpng.3 so that "doclifter" can process it.
Version 1.6.3beta09 [June 27, 2013]
Revised example.c to illustrate use of PNG_DEFAULT_sRGB and PNG_GAMMA_MAC_18
as parameters for png_set_gamma(). These have been available since
libpng-1.5.4.
Renamed contrib/tools/png-fix-too-far-back.c to pngfix.c and revised it
to check all compressed chunks known to libpng.
Version 1.6.3beta10 [July 5, 2013]
Updated documentation to show default behavior of benign errors correctly.
Only compile ARM code when PNG_READ_SUPPORTED is defined.
Fixed undefined behavior in contrib/tools/pngfix.c and added new strip
option. pngfix relied on undefined behavior and even a simple change from
gcc to g++ caused it to fail. The new strip option 'unsafe' has been
implemented and is the default if --max is given. Option names have
been clarified, with --strip=transform now stripping the bKGD chunk,
which was stripped previously with --strip=unused.
Added all documented chunk types to pngpriv.h
Unified pngfix.c source with libpng17.
Version 1.6.3rc01 [July 11, 2013]
No changes.
Version 1.6.3 [July 18, 2013]
Revised manual about changes in iTXt chunk handling made in libpng-1.6.0.
Added "/* SAFE */" comments in pngrutil.c and pngrtran.c where warnings
may be erroneously issued by code-checking applications.
Version 1.6.4beta01 [August 21, 2013]
Added information about png_set_options() to the manual.
Delay calling png_init_filter_functions() until a row with nonzero filter
is found.
Version 1.6.4beta02 [August 30, 2013]
Fixed inconsistent conditional compilation of png_chunk_unknown_handling()
prototype, definition, and usage. Made it depend on
PNG_HANDLE_AS_UNKNOWN_SUPPORTED everywhere.
Version 1.6.4rc01 [September 5, 2013]
No changes.
Version 1.6.4 [September 12, 2013]
No changes.
Version 1.6.5 [September 14, 2013]
Removed two stray lines of code from arm/arm_init.c.
Version 1.6.6 [September 16, 2013]
Removed two stray lines of code from arm/arm_init.c, again.
Version 1.6.7beta01 [September 30, 2013]
Revised unknown chunk code to correct several bugs in the NO_SAVE_/NO_WRITE
combination
Allow HANDLE_AS_UNKNOWN to work when other options are configured off. Also
fixed the pngminim makefiles to work when $(MAKEFLAGS) contains stuff
which terminates the make options (as by default in recent versions of
Gentoo).
Avoid up-cast warnings in pngvalid.c. On ARM the alignment requirements of
png_modifier are greater than that of png_store and as a consequence
compilation of pngvalid.c results in a warning about increased alignment
requirements because of the bare cast to (png_modifier*). The code is safe,
because the pointer is known to point to a stack allocated png_modifier,
but this change avoids the warning.
Fixed default behavior of ARM_NEON_API. If the ARM NEON API option was
compiled without the CHECK option it defaulted to on, not off.
Check user callback behavior in pngunknown.c. Previous versions compiled
if SAVE_UNKNOWN was not available but did nothing since the callback
was never implemented.
Merged pngunknown.c with 1.7 version and back ported 1.7 improvements/fixes
Version 1.6.7beta02 [October 12, 2013]
Made changes for compatibility with automake 1.14:
1) Added the 'compile' program to the list of programs that must be cleaned
in autogen.sh
2) Added 'subdir-objects' which causes .c files in sub-directories to be
compiled such that the corresponding .o files are also in the
sub-directory. This is because automake 1.14 warns that the
current behavior of compiling to the top level directory may be removed
in the future.
3) Updated dependencies on pnglibconf.h to match the new .o locations and
added all the files in contrib/libtests and contrib/tools that depend
on pnglibconf.h
4) Added 'BUILD_SOURCES = pnglibconf.h'; this is the automake recommended
way of handling the dependencies of sources that are machine generated;
unfortunately it only works if the user does 'make all' or 'make check',
so the dependencies (3) are still required.
Cleaned up (char*) casts of zlib messages. The latest version of the Intel C
compiler complains about casting a string literal as (char*), so copied the
treatment of z_const from the library code into pngfix.c
Simplified error message code in pngunknown. The simplification has the
useful side effect of avoiding a bogus warning generated by the latest
version of the Intel C compiler (it objects to
condition ? string-literal : string-literal).
Make autogen.sh work with automake 1.13 as well as 1.14. Do this by always
removing the 1.14 'compile' script but never checking for it.
Version 1.6.7beta03 [October 19, 2013]
Added ARMv8 support (James Yu <james.yu at linaro.org>). Added file
arm/filter_neon_intrinsics.c; enable with -mfpu=neon.
Revised pngvalid to generate size images with as many filters as it can
manage, limited by the number of rows.
Cleaned up ARM NEON compilation handling. The tests are now in pngpriv.h
and detect the broken GCC compilers.
Version 1.6.7beta04 [October 26, 2013]
Allow clang derived from older GCC versions to use ARM intrinsics. This
causes all clang builds that use -mfpu=neon to use the intrinsics code,
not the assembler code. This has only been tested on iOS 7. It may be
necessary to exclude some earlier clang versions but this seems unlikely.
Changed NEON implementation selection mechanism. This allows assembler
or intrinsics to be turned on at compile time during the build by defining
PNG_ARM_NEON_IMPLEMENTATION to the correct value (2 or 1). This macro
is undefined by default and the build type is selected in pngpriv.h.
Version 1.6.7rc01 [November 2, 2013]
No changes.
Version 1.6.7rc02 [November 7, 2013]
Fixed #include in filter_neon_intrinsics.c and ctype macros. The ctype char
checking macros take an unsigned char argument, not a signed char.
Version 1.6.7 [November 14, 2013]
No changes.
Version 1.6.8beta01 [November 24, 2013]
Moved prototype for png_handle_unknown() in pngpriv.h outside of
the #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED/#endif block.
Added "-Wall" to CFLAGS in contrib/pngminim/*/makefile
Conditionally compile some unused functions reported by -Wall in
pngminim.
Fixed 'minimal' builds. Various obviously useful minimal configurations
don't build because of missing contrib/libtests test programs and
overly complex dependencies in scripts/pnglibconf.dfa. This change
adds contrib/conftest/*.dfa files that can be used in automatic build
scripts to ensure that these configurations continue to build.
Enabled WRITE_INVERT and WRITE_PACK in contrib/pngminim/encoder.
Fixed pngvalid 'fail' function declaration on the Intel C Compiler.
This reverts to the previous 'static' implementation and works round
the 'unused static function' warning by using PNG_UNUSED().
Version 1.6.8beta02 [November 30, 2013]
Removed or marked PNG_UNUSED some harmless "dead assignments" reported
by clang scan-build.
Changed tabs to 3 spaces in png_debug macros and changed '"%s"m'
to '"%s" m' to improve portability among compilers.
Changed png_free_default() to free() in pngtest.c
Version 1.6.8rc01 [December 12, 2013]
Tidied up pngfix inits and fixed pngtest no-write builds.
Version 1.6.8rc02 [December 14, 2013]
Handle zero-length PLTE chunk or NULL palette with png_error()
instead of png_chunk_report(), which by default issues a warning
rather than an error, leading to later reading from a NULL pointer
(png_ptr->palette) in png_do_expand_palette(). This is CVE-2013-6954
and VU#650142. Libpng-1.6.1 through 1.6.7 are vulnerable.
Libpng-1.6.0 and earlier do not have this bug.
Version 1.6.8 [December 19, 2013]
No changes.
Version 1.6.9beta01 [December 26, 2013]
Bookkeeping: Moved functions around (no changes). Moved transform
function definitions before the place where they are called so that
they can be made static. Move the intrapixel functions and the
grayscale palette builder out of the png?tran.c files. The latter
isn't a transform function and is no longer used internally, and the
former MNG specific functions are better placed in pngread/pngwrite.c
Made transform implementation functions static. This makes the internal
functions called by png_do_{read|write}_transformations static. On an
x86-64 DLL build (Gentoo Linux) this reduces the size of the text
segment of the DLL by 1208 bytes, about 0.6%. It also simplifies
maintenance by removing the declarations from pngpriv.h and allowing
easier changes to the internal interfaces.
Rebuilt configure scripts with automake-1.14.1 and autoconf-2.69
in the tar distributions.
Version 1.6.9beta02 [January 1, 2014]
Added checks for libpng 1.5 to pngvalid.c. This supports the use of
this version of pngvalid in libpng 1.5
Merged with pngvalid.c from libpng-1.7 changes to create a single
pngvalid.c
Removed #error macro from contrib/tools/pngfix.c (Thomas Klausner).
Merged pngrio.c, pngtrans.c, pngwio.c, and pngerror.c with libpng-1.7.0
Merged libpng-1.7.0 changes to make no-interlace configurations work
with test programs.
Revised pngvalid.c to support libpng 1.5, which does not support the
PNG_MAXIMUM_INFLATE_WINDOW option, so #define it out when appropriate in
pngvalid.c
Allow unversioned links created on install to be disabled in configure.
In configure builds 'make install' changes/adds links like png.h
and libpng.a to point to the newly installed, versioned, files (e.g.
libpng17/png.h and libpng17.a). Three new configure options and some
rearrangement of Makefile.am allow creation of these links to be disabled.
Version 1.6.9beta03 [January 10, 2014]
Removed potentially misleading warning from png_check_IHDR().
Version 1.6.9beta04 [January 20, 2014]
Updated scripts/makefile.* to use CPPFLAGS (Cosmin).
Added clang attribute support (Cosmin).
Version 1.6.9rc01 [January 28, 2014]
No changes.
Version 1.6.9rc02 [January 30, 2014]
Quiet an uninitialized memory warning from VC2013 in png_get_png().
Version 1.6.9 [February 6, 2014]
Version 1.6.10beta01 [February 9, 2014]
Backported changes from libpng-1.7.0beta30 and beta31:
Fixed a large number of instances where PNGCBAPI was omitted from
function definitions.
Added pngimage test program for png_read_png() and png_write_png()
with two new test scripts.
Removed dependence on !PNG_READ_EXPAND_SUPPORTED for calling
png_set_packing() in png_read_png().
Fixed combination of ~alpha with shift. On read invert alpha, processing
occurred after shift processing, which causes the final values to be
outside the range that should be produced by the shift. Reversing the
order on read makes the two transforms work together correctly and mirrors
the order used on write.
Do not read invalid sBIT chunks. Previously libpng only checked sBIT
values on write, so a malicious PNG writer could therefore cause
the read code to return an invalid sBIT chunk, which might lead to
application errors or crashes. Such chunks are now skipped (with
chunk_benign_error).
Make png_read_png() and png_write_png() prototypes in png.h depend
upon PNG_READ_SUPPORTED and PNG_WRITE_SUPPORTED.
Support builds with unsupported PNG_TRANSFORM_* values. All of the
PNG_TRANSFORM_* values are always defined in png.h and, because they
are used for both read and write in some cases, it is not reliable
to #if out ones that are totally unsupported. This change adds error
detection in png_read_image() and png_write_image() to do a
png_app_error() if the app requests something that cannot be done
and it adds corresponding code to pngimage.c to handle such options
by not attempting to test them.
Version 1.6.10beta02 [February 23, 2014]
Moved redefines of png_error(), png_warning(), png_chunk_error(),
and png_chunk_warning() from pngpriv.h to png.h to make them visible
to libpng-calling applications.
Moved OS dependent code from arm/arm_init.c, to allow the included
implementation of the ARM NEON discovery function to be set at
build-time and provide sample implementations from the current code in the
contrib/arm-neon subdirectory. The __linux__ code has also been changed to
compile and link on Android by using /proc/cpuinfo, and the old linux code
is in contrib/arm-neon/linux-auxv.c. The new code avoids POSIX and Linux
dependencies apart from opening /proc/cpuinfo and is C90 compliant.
Check for info_ptr == NULL early in png_read_end() so we don't need to
run all the png_handle_*() and depend on them to return if info_ptr == NULL.
This improves the performance of png_read_end(png_ptr, NULL) and makes
it more robust against future programming errors.
Check for __has_extension before using it in pngconf.h, to
support older Clang versions (Jeremy Sequoia).
Treat CRC error handling with png_set_crc_action(), instead of with
png_set_benign_errors(), which has been the case since libpng-1.6.0beta18.
Use a user warning handler in contrib/gregbook/readpng2.c instead of default,
so warnings will be put on stderr even if libpng has CONSOLE_IO disabled.
Added png_ptr->process_mode = PNG_READ_IDAT_MODE in png_push_read_chunk
after recognizing the IDAT chunk, which avoids an infinite loop while
reading a datastream whose first IDAT chunk is of zero-length.
This fixes CERT VU#684412 and CVE-2014-0333.
Don't recognize known sRGB profiles as sRGB if they have been hacked,
but don't reject them and don't issue a copyright violation warning.
Version 1.6.10beta03 [February 25, 2014]
Moved some documentation from png.h to libpng.3 and libpng-manual.txt
Minor editing of contrib/arm-neon/README and contrib/examples/*.c
Version 1.6.10rc01 [February 27, 2014]
Fixed typos in the manual and in scripts/pnglibconf.dfa (CFLAGS -> CPPFLAGS
and PNG_USR_CONFIG -> PNG_USER_CONFIG).
Version 1.6.10rc02 [February 28, 2014]
Removed unreachable return statement after png_chunk_error()
in pngrutil.c
Version 1.6.10rc03 [March 4, 2014]
Un-deprecated png_data_freer().
Version 1.6.10 [March 6, 2014]
No changes.
Version 1.6.11beta01 [March 17, 2014]
Use "if (value != 0)" instead of "if (value)" consistently.
Changed ZlibSrcDir from 1.2.5 to 1.2.8 in projects/vstudio.
Moved configuration information from the manual to the INSTALL file.
Version 1.6.11beta02 [April 6, 2014]
Removed #if/#else/#endif from inside two pow() calls in pngvalid.c because
they were handled improperly by Portland Group's PGI-14.1 - PGI-14.3
when using its "__builtin_pow()" function.
Silence 'unused parameter' build warnings (Cosmin Truta).
$(CP) is now used alongside $(RM_F). Also, use 'copy' instead of 'cp'
where applicable, and applied other minor makefile changes (Cosmin).
Don't warn about invalid dimensions exceeding user limits (Cosmin).
Allow an easy replacement of the default pre-built configuration
header with a custom header, via the make PNGLIBCONF_H_PREBUILT
macro (Cosmin).
Version 1.6.11beta03 [April 6, 2014]
Fixed a typo in pngrutil.c, introduced in libpng-1.5.6, that interferes
with "blocky" expansion of sub-8-bit interlaced PNG files (Eric Huss).
Optionally use __builtin_bswap16() in png_do_swap().
Version 1.6.11beta04 [April 19, 2014]
Made progressive reading of interlaced images consistent with the
behavior of the sequential reader and consistent with the manual, by
moving some code out of the PNG_READ_INTERLACING_SUPPORTED blocks. The
row_callback now receives the proper pass number and unexpanded rows, when
png_combine_row() isn't built or used, and png_set_interlace_handling()
is not called.
Allow PNG_sRGB_PROFILE_CHECKING = (-1) to mean no sRGB profile checking.
Version 1.6.11beta05 [April 26, 2014]
Do not reject ICC V2 profiles that lack padding (Kai-Uwe Behrmann).
Relocated closing bracket of the sRGB profile test loop to avoid getting
"Not recognizing known sRGB profile that has been edited" warning for
ICC V2 profiles that lack the MD5 signature in the profile header.
Version 1.6.11beta06 [May 19, 2014]
Added PNG_SKIP_sRGB_CHECK_PROFILE choice for png_set_option().
Version 1.6.11rc01 [May 27, 2014]
No changes.
Version 1.6.11rc02 [June 3, 2014]
Test ZLIB_VERNUM instead of PNG_ZLIB_VERNUM in contrib/tools/pngfix.c
Version 1.6.11 [June 5, 2014]
No changes.
Version 1.6.12rc01 [June 6, 2014]
Relocated new code from 1.6.11beta06 in png.c to a point after the
declarations (Max Stepin).
Version 1.6.12rc02 [June 7, 2014]
Changed file permissions of contrib/tools/intgamma.sh,
test-driver, and compile from 0644 to 0755 (Cosmin).
Version 1.6.12rc03 [June 8, 2014]
Ensure "__has_attribute()" macro exists before trying to use it with
old clang compilers (MacPorts Ticket #43939).
Version 1.6.12 [June 12, 2014]
No changes.
Version 1.6.13beta01 [July 4, 2014]
Quieted -Wsign-compare and -Wclobber compiler warnings in
contrib/pngminus/*.c
Added "(void) png_ptr;" where needed in contrib/gregbook to quiet
compiler complaints about unused pointers.
Split a long output string in contrib/gregbook/rpng2-x.c.
Added "PNG_SET_OPTION" requirement for sRGB chunk support to pnglibconf.dfa,
Needed for write-only support (John Bowler).
Changed "if defined(__ARM_NEON__)" to
"if (defined(__ARM_NEON__) || defined(__ARM_NEON))" (James Wu).
Fixed clang no-warning builds: png_digit was defined but never used.
Version 1.6.13beta02 [July 21, 2014]
Fixed an incorrect separator ("/" should be "\") in scripts/makefile.vcwin32
(bug report from Wolfgang S. Kechel). Bug was introduced in libpng-1.6.11.
Also fixed makefile.bc32, makefile.bor, makefile.msc, makefile.intel, and
makefile.tc3 similarly.
Version 1.6.13beta03 [August 3, 2014]
Removed scripts/makefile.elf. It has not worked since libpng-1.5.0beta14
due to elimination of the PNG_FUNCTION_EXPORT and PNG_DATA_EXPORT
definitions from pngconf.h.
Ensure that CMakeLists.txt makes the target "lib" directory before making
symbolic link into it (SourceForge bug report #226 by Rolf Timmermans).
Version 1.6.13beta04 [August 8, 2014]
Added opinion that the ECCN (Export Control Classification Number) for
libpng is EAR99 to the README file.
Eliminated use of "$<" in makefile explicit rules, when copying
$PNGLIBCONF_H_PREBUILT. This does not work on some versions of make;
bug introduced in libpng version 1.6.11.
Version 1.6.13rc01 [August 14, 2014]
Made "ccopts" agree with "CFLAGS" in scripts/makefile.hp* and makefile.*sunu
Version 1.6.13 [August 21, 2014]
No changes.
Version 1.6.14beta01 [September 14, 2014]
Guard usage of png_ptr->options with #ifdef PNG_SET_OPTION_SUPPORTED.
Do not build contrib/tools/pngfix.c when PNG_SETJMP_NOT_SUPPORTED,
to allow "make" to complete without setjmp support (bug report by
Claudio Fontana)
Add "#include <setjmp.h>" to contrib/tools/pngfix.c (John Bowler)
Version 1.6.14beta02 [September 18, 2014]
Use nanosleep() instead of usleep() in contrib/gregbook/rpng2-x.c
because usleep() is deprecated.
Define usleep() in contrib/gregbook/rpng2-x.c if not already defined
in unistd.h and nanosleep() is not available; fixes error introduced
in libpng-1.6.13.
Disable floating point exception handling in pngvalid.c when
PNG_FLOATING_ARITHMETIC is not supported (bug report by "zootus
at users.sourceforge.net").
Version 1.6.14beta03 [September 19, 2014]
Define FE_DIVBYZERO, FE_INVALID, and FE_OVERFLOW in pngvalid.c if not
already defined. Revert floating point exception handling in pngvalid.c
to version 1.6.14beta01 behavior.
Version 1.6.14beta04 [September 27, 2014]
Fixed incorrect handling of the iTXt compression flag in pngrutil.c
(bug report by Shunsaku Hirata). Bug was introduced in libpng-1.6.0.
Version 1.6.14beta05 [October 1, 2014]
Added "option READ_iCCP enables READ_COMPRESSED_TEXT" to pnglibconf.dfa
Version 1.6.14beta06 [October 5, 2014]
Removed unused "text_len" parameter from private function png_write_zTXt().
Conditionally compile some code in png_deflate_claim(), when
PNG_WARNINGS_SUPPORTED and PNG_ERROR_TEXT_SUPPORTED are disabled.
Replaced repeated code in pngpread.c with PNG_PUSH_SAVE_BUFFER_IF_FULL.
Added "chunk iTXt enables TEXT" and "chunk zTXt enables TEXT"
to pnglibconf.dfa.
Removed "option READ_COMPRESSED_TEXT enables READ_TEXT" from pnglibconf.dfa,
to make it possible to configure a libpng that supports iCCP but not TEXT.
Version 1.6.14beta07 [October 7, 2014]
Removed "option WRITE_COMPRESSED_TEXT enables WRITE_TEXT" from pnglibconf.dfa
Only mark text chunks as written after successfully writing them.
Version 1.6.14rc01 [October 15, 2014]
Fixed some typos in comments.
Version 1.6.14rc02 [October 17, 2014]
Changed png_convert_to_rfc_1123() to png_convert_to_rfc_1123_buffer()
in the manual, to reflect the change made in libpng-1.6.0.
Updated README file to explain that direct access to the png_struct
and info_struct members has not been permitted since libpng-1.5.0.
Version 1.6.14 [October 23, 2014]
No changes.
Version 1.6.15beta01 [October 29, 2014]
Changed "if (!x)" to "if (x == 0)" and "if (x)" to "if (x != 0)"
Simplified png_free_data().
Added missing "ptr = NULL" after some instances of png_free().
Version 1.6.15beta02 [November 1, 2014]
Changed remaining "if (!x)" to "if (x == 0)" and "if (x)" to "if (x != 0)"
Version 1.6.15beta03 [November 3, 2014]
Added PNG_USE_ARM_NEON configuration flag (Marcin Juszkiewicz).
Version 1.6.15beta04 [November 4, 2014]
Removed new PNG_USE_ARM_NEON configuration flag and made a one-line
revision to configure.ac to support ARM on aarch64 instead (John Bowler).
Version 1.6.15beta05 [November 5, 2014]
Use png_get_libpng_ver(NULL) instead of PNG_LIBPNG_VER_STRING in
example.c, pngtest.c, and applications in the contrib directory.
Avoid out-of-bounds memory access in png_user_version_check().
Simplified and future-proofed png_user_version_check().
Fixed GCC unsigned int->float warnings. Various versions of GCC
seem to generate warnings when an unsigned value is implicitly
converted to double. This is probably a GCC bug but this change
avoids the issue by explicitly converting to (int) where safe.
Free all allocated memory in pngimage. The file buffer cache was left
allocated at the end of the program, harmless but it causes memory
leak reports from clang.
Fixed array size calculations to avoid warnings. At various points
in the code the number of elements in an array is calculated using
sizeof. This generates a compile time constant of type (size_t) which
is then typically assigned to an (unsigned int) or (int). Some versions
of GCC on 64-bit systems warn about the apparent narrowing, even though
the same compiler does apparently generate the correct, in-range,
numeric constant. This adds appropriate, safe, casts to make the
warnings go away.
Version 1.6.15beta06 [November 6, 2014]
Reverted use png_get_libpng_ver(NULL) instead of PNG_LIBPNG_VER_STRING
in the manual, example.c, pngtest.c, and applications in the contrib
directory. It was incorrect advice.
Version 1.6.15beta07 [November 7, 2014]
Removed #ifdef PNG_16BIT_SUPPORTED/#endif around png_product2(); it is
needed by png_reciprocal2().
Added #ifdef PNG_16BIT_SUPPORTED/#endif around png_log16bit() and
png_do_swap().
Changed all "#endif /* PNG_FEATURE_SUPPORTED */" to "#endif /* FEATURE */"
Version 1.6.15beta08 [November 8, 2014]
More housecleaning in *.h
Version 1.6.15rc01 [November 13, 2014]
Version 1.6.15rc02 [November 14, 2014]
The macros passed in the command line to Borland make were ignored if
similarly-named macros were already defined in makefiles. This behavior
src/Source/LibPNG/CHANGES view on Meta::CPAN
Added ".align 2" to arm/filter_neon.S to support old GAS assemblers that
don't do alignment correctly.
Revised Makefile.am and scripts/symbols.dfn to work with MinGW/MSYS
(Bob Friesenhahn).
Version 1.6.16beta02 [December 15, 2014]
Revised Makefile.am and scripts/*.dfn again to work with MinGW/MSYS;
renamed scripts/*.dfn to scripts/*.c (John Bowler).
Version 1.6.16beta03 [December 21, 2014]
Quiet a "comparison always true" warning in pngstest.c (John Bowler).
Version 1.6.16rc01 [December 21, 2014]
Restored a test on width that was removed from png.c at libpng-1.6.9
(Bug report by Alex Eubanks).
Version 1.6.16rc02 [December 21, 2014]
Undid the update to pngrutil.c in 1.6.16rc01.
Version 1.6.16rc03 [December 21, 2014]
Fixed an overflow in png_combine_row with very wide interlaced images.
Version 1.6.16 [December 22, 2014]
No changes.
Send comments/corrections/commendations to png-mng-implement at lists.sf.net
(subscription required; visit
https://lists.sourceforge.net/lists/listinfo/png-mng-implement
to subscribe)
or to glennrp at users.sourceforge.net
Glenn R-P
src/Source/LibPNG/CMakeLists.txt view on Meta::CPAN
# CMakeLists.txt
# Copyright (C) 2007-2014 Glenn Randers-Pehrson
# This code is released under the libpng license.
# For conditions of distribution and use, see the disclaimer
# and license in png.h
cmake_minimum_required(VERSION 2.4.4)
set(CMAKE_ALLOW_LOOSE_LOOP_CONSTRUCTS true)
set(CMAKE_CONFIGURATION_TYPES "Release;Debug;MinSizeRel;RelWithDebInfo")
project(libpng C)
enable_testing()
set(PNGLIB_MAJOR 1)
set(PNGLIB_MINOR 6)
set(PNGLIB_RELEASE 16)
set(PNGLIB_NAME libpng${PNGLIB_MAJOR}${PNGLIB_MINOR})
set(PNGLIB_VERSION ${PNGLIB_MAJOR}.${PNGLIB_MINOR}.${PNGLIB_RELEASE})
# needed packages
find_package(ZLIB REQUIRED)
include_directories(${ZLIB_INCLUDE_DIR})
if(NOT WIN32)
find_library(M_LIBRARY
NAMES m
PATHS /usr/lib /usr/local/lib
src/Source/LibPNG/CMakeLists.txt view on Meta::CPAN
option(PNG_SHARED "Build shared lib" ${PNG_SHARED})
else()
option(PNG_SHARED "Build shared lib" ON)
endif()
if(DEFINED PNG_STATIC)
option(PNG_STATIC "Build static lib" ${PNG_STATIC})
else()
option(PNG_STATIC "Build static lib" ON)
endif()
option(PNG_TESTS "Build libpng tests" YES)
# Many more configuration options could be added here
option(PNG_DEBUG "Build with debug output" NO)
option(PNGARG "Disable ANSI-C prototypes" NO)
# SET LIBNAME
set(PNG_LIB_NAME png${PNGLIB_MAJOR}${PNGLIB_MINOR})
# to distinguish between debug and release lib
set(CMAKE_DEBUG_POSTFIX "d")
# Use the prebuilt pnglibconf.h file from the scripts folder
# TODO: fix this by building with awk; without this no cmake build can be
# configured directly (to do so indirectly use your local awk to build a
# pnglibconf.h in the build directory.)
configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/pnglibconf.h.prebuilt
${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h)
include_directories(${CMAKE_CURRENT_BINARY_DIR})
# OUR SOURCES
set(libpng_public_hdrs
png.h
pngconf.h
${CMAKE_CURRENT_BINARY_DIR}/pnglibconf.h
)
set(libpng_sources
${libpng_public_hdrs}
pngdebug.h
pnginfo.h
pngpriv.h
pngstruct.h
png.c
pngerror.c
pngget.c
pngmem.c
pngpread.c
pngread.c
pngrio.c
pngrtran.c
pngrutil.c
pngset.c
pngtrans.c
pngwio.c
pngwrite.c
pngwtran.c
pngwutil.c
)
set(pngtest_sources
pngtest.c
)
set(pngvalid_sources
contrib/libtests/pngvalid.c
)
set(pngstest_sources
contrib/libtests/pngstest.c
)
# SOME NEEDED DEFINITIONS
if(MSVC)
add_definitions(-D_CRT_SECURE_NO_DEPRECATE)
endif(MSVC)
if(PNG_DEBUG)
add_definitions(-DPNG_DEBUG)
endif()
# NOW BUILD OUR TARGET
include_directories(${CMAKE_CURRENT_SOURCE_DIR} ${ZLIB_INCLUDE_DIR})
unset(PNG_LIB_TARGETS)
if(PNG_SHARED)
add_library(${PNG_LIB_NAME} SHARED ${libpng_sources})
set(PNG_LIB_TARGETS ${PNG_LIB_NAME})
if(MSVC)
# msvc does not append 'lib' - do it here to have consistent name
set_target_properties(${PNG_LIB_NAME} PROPERTIES PREFIX "lib")
set_target_properties(${PNG_LIB_NAME} PROPERTIES IMPORT_PREFIX "lib")
endif()
target_link_libraries(${PNG_LIB_NAME} ${ZLIB_LIBRARY} ${M_LIBRARY})
endif()
if(PNG_STATIC)
# does not work without changing name
set(PNG_LIB_NAME_STATIC ${PNG_LIB_NAME}_static)
add_library(${PNG_LIB_NAME_STATIC} STATIC ${libpng_sources})
list(APPEND PNG_LIB_TARGETS ${PNG_LIB_NAME_STATIC})
if(MSVC)
# msvc does not append 'lib' - do it here to have consistent name
set_target_properties(${PNG_LIB_NAME_STATIC} PROPERTIES PREFIX "lib")
endif()
target_link_libraries(${PNG_LIB_NAME_STATIC} ${ZLIB_LIBRARY} ${M_LIBRARY})
endif()
if(NOT PNG_LIB_TARGETS)
message(SEND_ERROR
"No library variant selected to build. "
"Please enable at least one of the following options: PNG_STATIC, PNG_SHARED")
endif()
if(PNG_SHARED AND WIN32)
set_target_properties(${PNG_LIB_NAME} PROPERTIES DEFINE_SYMBOL PNG_BUILD_DLL)
endif()
if(PNG_TESTS AND PNG_SHARED)
# does not work with msvc due to png_lib_ver issue
add_executable(pngtest ${pngtest_sources})
target_link_libraries(pngtest ${PNG_LIB_NAME})
add_test(pngtest ./pngtest ${CMAKE_CURRENT_SOURCE_DIR}/pngtest.png)
#
add_executable(pngvalid ${pngvalid_sources})
target_link_libraries(pngvalid ${PNG_LIB_NAME})
add_test(pngvalid ./pngvalid)
add_executable(pngstest ${pngstest_sources})
target_link_libraries(pngstest ${PNG_LIB_NAME})
add_test(pngstest ./pngstest
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g01.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g02.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g04.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g08.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn0g16.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn2c08.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn2c16.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn3p01.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn3p02.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn3p04.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn3p08.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn4a08.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn4a16.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn6a08.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/basn6a16.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn0g01.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn0g02.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn0g04.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn2c16.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbbn3p08.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbgn2c16.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbgn3p08.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbrn2c08.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbwn0g16.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbwn3p08.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftbyn3p08.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftp0n0g08.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftp0n2c08.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftp0n3p08.png
${CMAKE_CURRENT_SOURCE_DIR}/contrib/pngsuite/ftp1n3p08.png
)
endif()
# Ensure the CMAKE_LIBRARY_OUTPUT_DIRECTORY is set
IF(NOT CMAKE_LIBRARY_OUTPUT_DIRECTORY)
SET(CMAKE_LIBRARY_OUTPUT_DIRECTORY "lib")
ENDIF(NOT CMAKE_LIBRARY_OUTPUT_DIRECTORY)
# Set a variable with CMake code which:
# Creates a symlink from src to dest (if possible) or alternatively
src/Source/LibPNG/CMakeLists.txt view on Meta::CPAN
)
ADD_CUSTOM_TARGET(${DEST_FILE}_COPY ALL DEPENDS ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${DEST_FILE})
else(WIN32 AND NOT CYGWIN AND NOT MSYS)
get_filename_component(LINK_TARGET "${SRC_FILE}" NAME)
execute_process(COMMAND ${CMAKE_COMMAND} -E make_directory ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_LIBRARY_OUTPUT_DIRECTORY})
execute_process(COMMAND ${CMAKE_COMMAND} -E create_symlink "${LINK_TARGET}" ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${DEST_FILE} WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
execute_process(COMMAND ${CMAKE_COMMAND} -E create_symlink "${LINK_TARGET}" ${DEST_FILE} WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR})
endif(WIN32 AND NOT CYGWIN AND NOT MSYS)
endmacro()
# libpng is a library so default to 'lib'
if(NOT DEFINED CMAKE_INSTALL_LIBDIR)
set(CMAKE_INSTALL_LIBDIR lib)
endif(NOT DEFINED CMAKE_INSTALL_LIBDIR)
# CREATE PKGCONFIG FILES
# we use the same files like ./configure, so we have to set its vars
# Only do this on Windows for Cygwin - the files don't make much sense outside
# a UNIX look alike
if(NOT WIN32 OR CYGWIN OR MINGW)
set(prefix ${CMAKE_INSTALL_PREFIX})
set(exec_prefix ${CMAKE_INSTALL_PREFIX})
set(libdir ${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR})
set(includedir ${CMAKE_INSTALL_PREFIX}/include)
set(LIBS "-lz -lm")
configure_file(${CMAKE_CURRENT_SOURCE_DIR}/libpng.pc.in
${CMAKE_CURRENT_BINARY_DIR}/${PNGLIB_NAME}.pc @ONLY)
CREATE_SYMLINK(${PNGLIB_NAME}.pc libpng.pc)
configure_file(${CMAKE_CURRENT_SOURCE_DIR}/libpng-config.in
${CMAKE_CURRENT_BINARY_DIR}/${PNGLIB_NAME}-config @ONLY)
CREATE_SYMLINK(${PNGLIB_NAME}-config libpng-config)
endif(NOT WIN32 OR CYGWIN OR MINGW)
# SET UP LINKS
if(PNG_SHARED)
set_target_properties(${PNG_LIB_NAME} PROPERTIES
# VERSION 16.${PNGLIB_RELEASE}.1.6.16
VERSION 16.${PNGLIB_RELEASE}.0
SOVERSION 16
CLEAN_DIRECT_OUTPUT 1)
endif()
src/Source/LibPNG/CMakeLists.txt view on Meta::CPAN
set_target_properties(${PNG_LIB_NAME_STATIC} PROPERTIES
OUTPUT_NAME ${PNG_LIB_NAME}
CLEAN_DIRECT_OUTPUT 1)
endif()
endif()
# If CMake > 2.4.x, we set a variable used below to export
# targets to an export file.
# TODO: Use VERSION_GREATER after our cmake_minimum_required >= 2.6.2
if(CMAKE_MAJOR_VERSION GREATER 1 AND CMAKE_MINOR_VERSION GREATER 4)
set(PNG_EXPORT_RULE EXPORT libpng)
elseif(CMAKE_MAJOR_VERSION GREATER 2) # future proof
set(PNG_EXPORT_RULE EXPORT libpng)
endif()
# INSTALL
if(NOT SKIP_INSTALL_LIBRARIES AND NOT SKIP_INSTALL_ALL )
install(TARGETS ${PNG_LIB_TARGETS}
${PNG_EXPORT_RULE}
RUNTIME DESTINATION bin
LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})
if(PNG_SHARED)
# Create a symlink for libpng.dll.a => libpng16.dll.a on Cygwin
if(CYGWIN OR MINGW)
get_target_property(BUILD_TARGET_LOCATION ${PNG_LIB_NAME} LOCATION_${CMAKE_BUILD_TYPE})
CREATE_SYMLINK(${BUILD_TARGET_LOCATION} libpng${CMAKE_IMPORT_LIBRARY_SUFFIX})
install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng${CMAKE_IMPORT_LIBRARY_SUFFIX}
DESTINATION ${CMAKE_INSTALL_LIBDIR})
endif(CYGWIN OR MINGW)
if(NOT WIN32)
get_target_property(BUILD_TARGET_LOCATION ${PNG_LIB_NAME} LOCATION_${CMAKE_BUILD_TYPE})
CREATE_SYMLINK(${BUILD_TARGET_LOCATION} libpng${CMAKE_SHARED_LIBRARY_SUFFIX})
install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng${CMAKE_SHARED_LIBRARY_SUFFIX}
DESTINATION ${CMAKE_INSTALL_LIBDIR})
endif(NOT WIN32)
endif(PNG_SHARED)
if(PNG_STATIC)
if(NOT WIN32 OR CYGWIN OR MINGW)
get_target_property(BUILD_TARGET_LOCATION ${PNG_LIB_NAME_STATIC} LOCATION_${CMAKE_BUILD_TYPE})
CREATE_SYMLINK(${BUILD_TARGET_LOCATION} libpng${CMAKE_STATIC_LIBRARY_SUFFIX})
install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng${CMAKE_STATIC_LIBRARY_SUFFIX}
DESTINATION ${CMAKE_INSTALL_LIBDIR})
endif(NOT WIN32 OR CYGWIN OR MINGW)
endif()
endif()
if(NOT SKIP_INSTALL_HEADERS AND NOT SKIP_INSTALL_ALL )
install(FILES ${libpng_public_hdrs} DESTINATION include)
install(FILES ${libpng_public_hdrs} DESTINATION include/${PNGLIB_NAME})
endif()
if(NOT SKIP_INSTALL_EXECUTABLES AND NOT SKIP_INSTALL_ALL )
if(NOT WIN32 OR CYGWIN OR MINGW)
install(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/libpng-config DESTINATION bin)
install(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/${PNGLIB_NAME}-config
DESTINATION bin)
endif(NOT WIN32 OR CYGWIN OR MINGW)
endif()
if(NOT SKIP_INSTALL_FILES AND NOT SKIP_INSTALL_ALL )
# Install man pages
if(NOT PNG_MAN_DIR)
set(PNG_MAN_DIR "share/man")
endif()
install(FILES libpng.3 libpngpf.3 DESTINATION ${PNG_MAN_DIR}/man3)
install(FILES png.5 DESTINATION ${PNG_MAN_DIR}/man5)
# Install pkg-config files
if(NOT WIN32 OR CYGWIN OR MINGW)
install(FILES ${CMAKE_CURRENT_BINARY_DIR}/libpng.pc
DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
install(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/libpng-config
DESTINATION bin)
install(FILES ${CMAKE_CURRENT_BINARY_DIR}/${PNGLIB_NAME}.pc
DESTINATION ${CMAKE_INSTALL_LIBDIR}/pkgconfig)
install(PROGRAMS ${CMAKE_CURRENT_BINARY_DIR}/${PNGLIB_NAME}-config
DESTINATION bin)
endif(NOT WIN32 OR CYGWIN OR MINGW)
endif()
# On versions of CMake that support it, create an export file CMake
# users can include() to import our targets
if(PNG_EXPORT_RULE AND NOT SKIP_INSTALL_EXPORT AND NOT SKIP_INSTALL_ALL )
install(EXPORT libpng DESTINATION lib/libpng FILE lib${PNG_LIB_NAME}.cmake)
endif()
# what's with libpng-manual.txt and all the extra files?
# UNINSTALL
# do we need this?
# DIST
# do we need this?
# to create msvc import lib for mingw compiled shared lib
# pexports libpng.dll > libpng.def
# lib /def:libpng.def /machine:x86
src/Source/LibPNG/INSTALL view on Meta::CPAN
Installing libpng
Contents
I. Simple installation
II. Rebuilding the configure scripts
III. Using scripts/makefile*
IV. Using cmake
V. Directory structure
VI. Building with project files
VII. Building with makefiles
VIII. Configuring libpng for 16-bit platforms
IX. Configuring for DOS
X. Configuring for Medium Model
XI. Prepending a prefix to exported symbols
XII. Configuring for compiler xxx:
XIII. Removing unwanted object code
XIV. Changes to the build and configuration of libpng in libpng-1.5.x
XV. Configuring libpng for multiprocessing
XVI. Other sources of information about libpng
I. Simple installation
On Unix/Linux and similar systems, you can simply type
./configure [--prefix=/path]
make check
make install
and ignore the rest of this document. "/path" is the path to the directory
where you want to install the libpng "lib", "include", and "bin"
subdirectories.
If you downloaded a GIT clone, you will need to run ./autogen.sh before
running ./configure, to create "configure" and "Makefile.in" which are
not included in the GIT repository.
Note that "configure" is only included in the "*.tar" distributions and not
in the "*.zip" or "*.7z" distributions. If you downloaded one of those
distributions, see "Building with project files" or "Building with makefiles",
below.
src/Source/LibPNG/INSTALL view on Meta::CPAN
./configure [--prefix=/path] [other options]
make
make install
make check
III. Using scripts/makefile*
Instead, you can use one of the custom-built makefiles in the
"scripts" directory
cp scripts/pnglibconf.h.prebuilt pnglibconf.h
cp scripts/makefile.system makefile
make test
make install
The files that are presently available in the scripts directory
are listed and described in scripts/README.txt.
Or you can use one of the "projects" in the "projects" directory.
Before installing libpng, you must first install zlib, if it
is not already on your system. zlib can usually be found
wherever you got libpng; otherwise go to http://zlib.net. You can place
zlib in in the same directory as libpng or in another directory.
If your system already has a preinstalled zlib you will still need
to have access to the zlib.h and zconf.h include files that
correspond to the version of zlib that's installed.
If you wish to test with a particular zlib that is not first in the
standard library search path, put ZLIBLIB, ZLIBINC, CPPFLAGS, LDFLAGS,
and LD_LIBRARY_PATH in your environment before running "make test"
or "make distcheck":
src/Source/LibPNG/INSTALL view on Meta::CPAN
IV. Using cmake
If you want to use "cmake" (see www.cmake.org), type
cmake . -DCMAKE_INSTALL_PREFIX=/path
make
make install
As when using the simple configure method described above, "/path" points to
the installation directory where you want to put the libpng "lib", "include",
and "bin" subdirectories.
V. Directory structure
You can rename the directories that you downloaded (they
might be called "libpng-x.y.z" or "libpngNN" and "zlib-1.2.8"
or "zlib128") so that you have directories called "zlib" and "libpng".
Your directory structure should look like this:
.. (the parent directory)
libpng (this directory)
INSTALL (this file)
README
*.h, *.c => libpng source files
CMakeLists.txt => "cmake" script
configuration files:
configure.ac, configure, Makefile.am, Makefile.in,
autogen.sh, config.guess, ltmain.sh, missing, libpng.pc.in,
libpng-config.in, aclocal.m4, config.h.in, config.sub,
depcomp, install-sh, mkinstalldirs, test-pngtest.sh
contrib
arm-neon, conftest, examples, gregbook, libtests, pngminim,
pngminus, pngsuite, tools, visupng
projects
cbuilder5, owatcom, visualc71, vstudio, xcode
scripts
makefile.*
*.def (module definition files)
etc.
pngtest.png
etc.
zlib
README, *.h, *.c contrib, etc.
If the line endings in the files look funny, you may wish to get the other
distribution of libpng. It is available in both tar.gz (UNIX style line
endings) and zip (DOS style line endings) formats.
VI. Building with project files
If you are building libpng with MSVC, you can enter the
libpng projects\visualc71 or vstudio directory and follow the instructions
in README.txt.
Otherwise enter the zlib directory and follow the instructions in zlib/README,
then come back here and run "configure" or choose the appropriate
makefile.sys in the scripts directory.
VII. Building with makefiles
Copy the file (or files) that you need from the
scripts directory into this directory, for example
MSDOS example: copy scripts\makefile.msc makefile
copy scripts\pnglibconf.h.prebuilt pnglibconf.h
UNIX example: cp scripts/makefile.std makefile
cp scripts/pnglibconf.h.prebuilt pnglibconf.h
Read the makefile to see if you need to change any source or
target directories to match your preferences.
Then read pnglibconf.dfa to see if you want to make any configuration
changes.
Then just run "make" which will create the libpng library in
this directory and "make test" which will run a quick test that reads
the "pngtest.png" file and writes a "pngout.png" file that should be
identical to it. Look for "9782 zero samples" in the output of the
test. For more confidence, you can run another test by typing
"pngtest pngnow.png" and looking for "289 zero samples" in the output.
Also, you can run "pngtest -m contrib/pngsuite/*.png" and compare
your output with the result shown in contrib/pngsuite/README.
Most of the makefiles will allow you to run "make install" to
put the library in its final resting place (if you want to
do that, run "make install" in the zlib directory first if necessary).
Some also allow you to run "make test-installed" after you have
run "make install".
VIII. Configuring libpng for 16-bit platforms
You will want to look into zconf.h to tell zlib (and thus libpng) that
it cannot allocate more then 64K at a time. Even if you can, the memory
won't be accessible. So limit zlib and libpng to 64K by defining MAXSEG_64K.
IX. Configuring for DOS
For DOS users who only have access to the lower 640K, you will
have to limit zlib's memory usage via a png_set_compression_mem_level()
call. See zlib.h or zconf.h in the zlib library for more information.
X. Configuring for Medium Model
Libpng's support for medium model has been tested on most of the popular
compilers. Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets
defined, and FAR gets defined to far in pngconf.h, and you should be
all set. Everything in the library (except for zlib's structure) is
expecting far data. You must use the typedefs with the p or pp on
the end for pointers (or at least look at them and be careful). Make
note that the rows of data are defined as png_bytepp, which is
an "unsigned char far * far *".
XI. Prepending a prefix to exported symbols
Starting with libpng-1.6.0, you can configure libpng (when using the
"configure" script) to prefix all exported symbols by means of the
configuration option "--with-libpng-prefix=FOO_", where FOO_ can be any
string beginning with a letter and containing only uppercase
and lowercase letters, digits, and the underscore (i.e., a C language
identifier). This creates a set of macros in pnglibconf.h, so this is
transparent to applications; their function calls get transformed by
the macros to use the modified names.
XII. Configuring for compiler xxx:
All includes for libpng are in pngconf.h. If you need to add, change
or delete an include, this is the place to do it.
The includes that are not needed outside libpng are placed in pngpriv.h,
which is only used by the routines inside libpng itself.
The files in libpng proper only include pngpriv.h and png.h, which
in turn includes pngconf.h and, as of libpng-1.5.0, pnglibconf.h.
As of libpng-1.5.0, pngpriv.h also includes three other private header
files, pngstruct.h, pnginfo.h, and pngdebug.h, which contain material
that previously appeared in the public headers.
XIII. Removing unwanted object code
There are a bunch of #define's in pngconf.h that control what parts of
libpng are compiled. All the defines end in _SUPPORTED. If you are
never going to use a capability, you can change the #define to #undef
before recompiling libpng and save yourself code and data space, or
you can turn off individual capabilities with defines that begin with
PNG_NO_.
In libpng-1.5.0 and later, the #define's are in pnglibconf.h instead.
You can also turn all of the transforms and ancillary chunk capabilities
off en masse with compiler directives that define
PNG_NO_READ[or WRITE]_TRANSFORMS, or PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS,
or all four, along with directives to turn on any of the capabilities that
you do want. The PNG_NO_READ[or WRITE]_TRANSFORMS directives disable the
extra transformations but still leave the library fully capable of reading
and writing PNG files with all known public chunks. Use of the
PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS directive produces a library
that is incapable of reading or writing ancillary chunks. If you are
not using the progressive reading capability, you can turn that off
with PNG_NO_PROGRESSIVE_READ (don't confuse this with the INTERLACING
capability, which you'll still have).
All the reading and writing specific code are in separate files, so the
linker should only grab the files it needs. However, if you want to
make sure, or if you are building a stand alone library, all the
reading files start with "pngr" and all the writing files start with "pngw".
The files that don't match either (like png.c, pngtrans.c, etc.)
are used for both reading and writing, and always need to be included.
The progressive reader is in pngpread.c
If you are creating or distributing a dynamically linked library (a .so
or DLL file), you should not remove or disable any parts of the library,
as this will cause applications linked with different versions of the
library to fail if they call functions not available in your library.
The size of the library itself should not be an issue, because only
those sections that are actually used will be loaded into memory.
XIV. Changes to the build and configuration of libpng in libpng-1.5.x
Details of internal changes to the library code can be found in the CHANGES
file and in the GIT repository logs. These will be of no concern to the vast
majority of library users or builders; however, the few who configure libpng
to a non-default feature set may need to change how this is done.
There should be no need for library builders to alter build scripts if
these use the distributed build support - configure or the makefiles -
however, users of the makefiles may care to update their build scripts
to build pnglibconf.h where the corresponding makefile does not do so.
Building libpng with a non-default configuration has changed completely.
The old method using pngusr.h should still work correctly even though the
way pngusr.h is used in the build has been changed; however, library
builders will probably want to examine the changes to take advantage of
new capabilities and to simplify their build system.
A. Specific changes to library configuration capabilities
The exact mechanism used to control attributes of API functions has
changed. A single set of operating system independent macro definitions
is used and operating system specific directives are defined in
pnglibconf.h
As part of this the mechanism used to choose procedure call standards on
those systems that allow a choice has been changed. At present this only
affects certain Microsoft (DOS, Windows) and IBM (OS/2) operating systems
running on Intel processors. As before, PNGAPI is defined where required
to control the exported API functions; however, two new macros, PNGCBAPI
and PNGCAPI, are used instead for callback functions (PNGCBAPI) and
(PNGCAPI) for functions that must match a C library prototype (currently
only png_longjmp_ptr, which must match the C longjmp function.) The new
approach is documented in pngconf.h
Despite these changes, libpng 1.5.0 only supports the native C function
calling standard on those platforms tested so far (__cdecl on Microsoft
Windows). This is because the support requirements for alternative
calling conventions seem to no longer exist. Developers who find it
necessary to set PNG_API_RULE to 1 should advise the mailing list
(png-mng-implement) of this and library builders who use Openwatcom and
therefore set PNG_API_RULE to 2 should also contact the mailing list.
B. Changes to the configuration mechanism
Prior to libpng-1.5.0 library builders who needed to configure libpng
had either to modify the exported pngconf.h header file to add system
specific configuration or had to write feature selection macros into
pngusr.h and cause this to be included into pngconf.h by defining
PNG_USER_CONFIG. The latter mechanism had the disadvantage that an
application built without PNG_USER_CONFIG defined would see the
unmodified, default, libpng API and thus would probably fail to link.
These mechanisms still work in the configure build and in any makefile
build that builds pnglibconf.h, although the feature selection macros
have changed somewhat as described above. In 1.5.0, however, pngusr.h is
processed only once, at the time the exported header file pnglibconf.h is
built. pngconf.h no longer includes pngusr.h; therefore, pngusr.h is ignored
after the build of pnglibconf.h and it is never included in an application
build.
The formerly used alternative of adding a list of feature macros to the
CPPFLAGS setting in the build also still works; however, the macros will be
copied to pnglibconf.h and this may produce macro redefinition warnings
when the individual C files are compiled.
All configuration now only works if pnglibconf.h is built from
scripts/pnglibconf.dfa. This requires the program awk. Brian Kernighan
(the original author of awk) maintains C source code of that awk and this
and all known later implementations (often called by subtly different
names - nawk and gawk for example) are adequate to build pnglibconf.h.
The Sun Microsystems (now Oracle) program 'awk' is an earlier version
and does not work; this may also apply to other systems that have a
functioning awk called 'nawk'.
Configuration options are now documented in scripts/pnglibconf.dfa. This
file also includes dependency information that ensures a configuration is
consistent; that is, if a feature is switched off, dependent features are
also switched off. As a recommended alternative to using feature macros in
pngusr.h a system builder may also define equivalent options in pngusr.dfa
(or, indeed, any file) and add that to the configuration by setting
DFA_XTRA to the file name. The makefiles in contrib/pngminim illustrate
how to do this, and also illustrate a case where pngusr.h is still required.
After you have built libpng, the definitions that were recorded in
pnglibconf.h are available to your application (pnglibconf.h is included
in png.h and gets installed alongside png.h and pngconf.h in your
$PREFIX/include directory). Do not edit pnglibconf.h after you have built
libpng, because than the settings would not accurately reflect the settings
that were used to build libpng.
XV. Configuring libpng for multiprocessing
Libpng uses setjmp()/longjmp() for error handling. Unfortunately setjmp()
is known to be not thread-safe on some platforms and we don't know of
any platform where it is guaranteed to be thread-safe. Therefore, if
your application is going to be using multiple threads, you should
configure libpng with PNG_NO_SETJMP in your pngusr.dfa file, with
-DPNG_NO_SETJMP on your compile line, or with
#undef PNG_SETJMP_SUPPORTED
in your pnglibconf.h or pngusr.h.
XVI. Other sources of information about libpng:
Further information can be found in the README and libpng-manual.txt
files, in the individual makefiles, in png.h, and the manual pages
libpng.3 and png.5.
src/Source/LibPNG/LICENSE view on Meta::CPAN
This copy of the libpng notices is provided for your convenience. In case of
any discrepancy between this copy and the notices in the file png.h that is
included in the libpng distribution, the latter shall prevail.
COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
If you modify libpng you may insert additional notices immediately following
this sentence.
This code is released under the libpng license.
libpng versions 1.2.6, August 15, 2004, through 1.6.16, December 22, 2014, are
Copyright (c) 2004, 2006-2014 Glenn Randers-Pehrson, and are
distributed according to the same disclaimer and license as libpng-1.2.5
with the following individual added to the list of Contributing Authors
Cosmin Truta
libpng versions 1.0.7, July 1, 2000, through 1.2.5 - October 3, 2002, are
Copyright (c) 2000-2002 Glenn Randers-Pehrson, and are
distributed according to the same disclaimer and license as libpng-1.0.6
with the following individuals added to the list of Contributing Authors
Simon-Pierre Cadieux
Eric S. Raymond
Gilles Vollant
and with the following additions to the disclaimer:
There is no warranty against interference with your enjoyment of the
library or against infringement. There is no warranty that our
efforts or the library will fulfill any of your particular purposes
or needs. This library is provided with all faults, and the entire
risk of satisfactory quality, performance, accuracy, and effort is with
the user.
libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
Copyright (c) 1998, 1999 Glenn Randers-Pehrson, and are
distributed according to the same disclaimer and license as libpng-0.96,
with the following individuals added to the list of Contributing Authors:
Tom Lane
Glenn Randers-Pehrson
Willem van Schaik
libpng versions 0.89, June 1996, through 0.96, May 1997, are
Copyright (c) 1996, 1997 Andreas Dilger
Distributed according to the same disclaimer and license as libpng-0.88,
with the following individuals added to the list of Contributing Authors:
John Bowler
Kevin Bracey
Sam Bushell
Magnus Holmgren
Greg Roelofs
Tom Tanner
libpng versions 0.5, May 1995, through 0.88, January 1996, are
Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
For the purposes of this copyright and license, "Contributing Authors"
is defined as the following set of individuals:
Andreas Dilger
Dave Martindale
Guy Eric Schalnat
Paul Schmidt
Tim Wegner
src/Source/LibPNG/LICENSE view on Meta::CPAN
3. This Copyright notice may not be removed or altered from any
source or altered source distribution.
The Contributing Authors and Group 42, Inc. specifically permit, without
fee, and encourage the use of this source code as a component to
supporting the PNG file format in commercial products. If you use this
source code in a product, acknowledgment is not required but would be
appreciated.
A "png_get_copyright" function is available, for convenient use in "about"
boxes and the like:
printf("%s",png_get_copyright(NULL));
Also, the PNG logo (in PNG format, of course) is supplied in the
files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
Libpng is OSI Certified Open Source Software. OSI Certified Open Source is a
certification mark of the Open Source Initiative.
Glenn Randers-Pehrson
glennrp at users.sourceforge.net
December 22, 2014
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README for libpng version 1.6.16 - December 22, 2014 (shared library 16.0)
See the note about version numbers near the top of png.h
See INSTALL for instructions on how to install libpng.
Libpng comes in several distribution formats. Get libpng-*.tar.gz or
libpng-*.tar.xz or if you want UNIX-style line endings in the text files,
or lpng*.7z or lpng*.zip if you want DOS-style line endings.
Version 0.89 was the first official release of libpng. Don't let the
fact that it's the first release fool you. The libpng library has been in
extensive use and testing since mid-1995. By late 1997 it had
finally gotten to the stage where there hadn't been significant
changes to the API in some time, and people have a bad feeling about
libraries with versions < 1.0. Version 1.0.0 was released in
March 1998.
****
Note that some of the changes to the png_info structure render this
version of the library binary incompatible with libpng-0.89 or
earlier versions if you are using a shared library. The type of the
"filler" parameter for png_set_filler() has changed from png_byte to
png_uint_32, which will affect shared-library applications that use
this function.
To avoid problems with changes to the internals of png info_struct,
new APIs have been made available in 0.95 to avoid direct application
access to info_ptr. These functions are the png_set_<chunk> and
png_get_<chunk> functions. These functions should be used when
accessing/storing the info_struct data, rather than manipulating it
directly, to avoid such problems in the future.
It is important to note that the APIs did not make current programs
that access the info struct directly incompatible with the new
library, through libpng-1.2.x. In libpng-1.4.x, which was meant to
be a transitional release, members of the png_struct and the
info_struct can still be accessed, but the compiler will issue a
warning about deprecated usage. Since libpng-1.5.0, direct access
to these structs is not allowed, and the definitions of the structs
reside in private pngstruct.h and pnginfo.h header files that are not
accessible to applications. It is strongly suggested that new
programs use the new APIs (as shown in example.c and pngtest.c), and
older programs be converted to the new format, to facilitate upgrades
in the future.
****
Additions since 0.90 include the ability to compile libpng as a
Windows DLL, and new APIs for accessing data in the info struct.
Experimental functions include the ability to set weighting and cost
factors for row filter selection, direct reads of integers from buffers
on big-endian processors that support misaligned data access, faster
methods of doing alpha composition, and more accurate 16->8 bit color
conversion.
The additions since 0.89 include the ability to read from a PNG stream
which has had some (or all) of the signature bytes read by the calling
application. This also allows the reading of embedded PNG streams that
do not have the PNG file signature. As well, it is now possible to set
the library action on the detection of chunk CRC errors. It is possible
to set different actions based on whether the CRC error occurred in a
critical or an ancillary chunk.
The changes made to the library, and bugs fixed are based on discussions
on the PNG-implement mailing list and not on material submitted
privately to Guy, Andreas, or Glenn. They will forward any good
suggestions to the list.
For a detailed description on using libpng, read libpng-manual.txt. For
examples of libpng in a program, see example.c and pngtest.c. For usage
information and restrictions (what little they are) on libpng, see
png.h. For a description on using zlib (the compression library used by
libpng) and zlib's restrictions, see zlib.h
I have included a general makefile, as well as several machine and
compiler specific ones, but you may have to modify one for your own needs.
You should use zlib 1.0.4 or later to run this, but it MAY work with
versions as old as zlib 0.95. Even so, there are bugs in older zlib
versions which can cause the output of invalid compression streams for
some images. You will definitely need zlib 1.0.4 or later if you are
taking advantage of the MS-DOS "far" structure allocation for the small
and medium memory models. You should also note that zlib is a
compression library that is useful for more things than just PNG files.
You can use zlib as a drop-in replacement for fread() and fwrite() if
you are so inclined.
zlib should be available at the same place that libpng is, or at zlib.net.
You may also want a copy of the PNG specification. It is available
as an RFC, a W3C Recommendation, and an ISO/IEC Standard. You can find
these at http://www.libpng.org/pub/png/documents/
This code is currently being archived at libpng.sf.net in the
[DOWNLOAD] area, and at ftp://ftp.simplesystems.org. If you can't find it
in any of those places, e-mail me, and I'll help you find it.
I am not a lawyer, but I believe that the Export Control Classification
Number (ECCN) for libpng is EAR99, which means not subject to export
controls or International Traffic in Arms Regulations (ITAR) because it
is open source, publicly available software, that does not contain any
encryption software. See the EAR, paragraphs 734.3(b)(3) and 734.7(b).
If you have any code changes, requests, problems, etc., please e-mail
them to me. Also, I'd appreciate any make files or project files,
and any modifications you needed to make to get libpng to compile,
along with a #define variable to tell what compiler/system you are on.
If you needed to add transformations to libpng, or wish libpng would
provide the image in a different way, drop me a note (and code, if
possible), so I can consider supporting the transformation.
Finally, if you get any warning messages when compiling libpng
(note: not zlib), and they are easy to fix, I'd appreciate the
fix. Please mention "libpng" somewhere in the subject line. Thanks.
This release was created and will be supported by myself (of course
based in a large way on Guy's and Andreas' earlier work), and the PNG
development group.
Send comments/corrections/commendations to png-mng-implement at
lists.sourceforge.net (subscription required; visit
https://lists.sourceforge.net/lists/listinfo/png-mng-implement
to subscribe) or to glennrp at users.sourceforge.net
You can't reach Guy, the original libpng author, at the addresses
given in previous versions of this document. He and Andreas will
read mail addressed to the png-implement list, however.
Please do not send general questions about PNG. Send them to
png-mng-misc at lists.sf.net (subscription required; visit
https://lists.sourceforge.net/lists/listinfo/png-mng-misc to
subscribe). If you have a question about something
in the PNG specification that is related to using libpng, send it
to me. Send me any questions that start with "I was using libpng,
and ...". If in doubt, send questions to me. I'll bounce them
to others, if necessary.
Please do not send suggestions on how to change PNG. We have
been discussing PNG for nineteen years now, and it is official and
finished. If you have suggestions for libpng, however, I'll
gladly listen. Even if your suggestion is not used immediately,
it may be used later.
Files in this distribution:
ANNOUNCE => Announcement of this version, with recent changes
CHANGES => Description of changes between libpng versions
KNOWNBUG => List of known bugs and deficiencies
LICENSE => License to use and redistribute libpng
README => This file
TODO => Things not implemented in the current library
Y2KINFO => Statement of Y2K compliance
example.c => Example code for using libpng functions
libpng.3 => manual page for libpng (includes libpng-manual.txt)
libpng-manual.txt => Description of libpng and its functions
libpngpf.3 => manual page for libpng's private functions
png.5 => manual page for the PNG format
png.c => Basic interface functions common to library
png.h => Library function and interface declarations (public)
pngpriv.h => Library function and interface declarations (private)
pngconf.h => System specific library configuration (public)
pngstruct.h => png_struct declaration (private)
pnginfo.h => png_info struct declaration (private)
pngdebug.h => debugging macros (private)
pngerror.c => Error/warning message I/O functions
pngget.c => Functions for retrieving info from struct
pngmem.c => Memory handling functions
pngbar.png => PNG logo, 88x31
pngnow.png => PNG logo, 98x31
pngpread.c => Progressive reading functions
pngread.c => Read data/helper high-level functions
pngrio.c => Lowest-level data read I/O functions
pngrtran.c => Read data transformation functions
pngrutil.c => Read data utility functions
pngset.c => Functions for storing data into the info_struct
pngtest.c => Library test program
pngtest.png => Library test sample image
pngtrans.c => Common data transformation functions
pngwio.c => Lowest-level write I/O functions
pngwrite.c => High-level write functions
pngwtran.c => Write data transformations
pngwutil.c => Write utility functions
arm => Contains optimized code for the ARM platform
contrib => Contributions
examples => Example programs
gregbook => source code for PNG reading and writing, from
Greg Roelofs' "PNG: The Definitive Guide",
O'Reilly, 1999
libtests => Test programs
pngminim => Minimal decoder, encoder, and progressive decoder
programs demonstrating use of pngusr.dfa
pngminus => Simple pnm2png and png2pnm programs
pngsuite => Test images
tools => Various tools
visupng => Contains a MSVC workspace for VisualPng
projects => Contains project files and workspaces for
building a DLL
owatcom => Contains a WATCOM project for building libpng
visualc71 => Contains a Microsoft Visual C++ (MSVC)
workspace for building libpng and zlib
vstudio => Contains a Microsoft Visual C++ (MSVC)
workspace for building libpng and zlib
scripts => Directory containing scripts for building libpng:
(see scripts/README.txt for the list of scripts)
Good luck, and happy coding.
-Glenn Randers-Pehrson (current maintainer, since 1998)
Internet: glennrp at users.sourceforge.net
-Andreas Eric Dilger (former maintainer, 1996-1997)
Internet: adilger at enel.ucalgary.ca
Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/
src/Source/LibPNG/TODO view on Meta::CPAN
/*
TODO - list of things to do for libpng:
Final bug fixes.
Better C++ wrapper/full C++ implementation?
Fix problem with C++ and EXTERN "C".
cHRM transformation.
Remove setjmp/longjmp usage in favor of returning error codes.
Palette creation.
Add "grayscale->palette" transformation and "palette->grayscale" detection.
Improved dithering.
Multi-lingual error and warning message support.
Complete sRGB transformation (presently it simply uses gamma=0.45455).
Make profile checking optional via a png_set_something() call.
Man pages for function calls.
Better documentation.
Better filter selection
(counting huffman bits/precompression? filter inertia? filter costs?).
Histogram creation.
Text conversion between different code pages (Latin-1 -> Mac and DOS).
Avoid building gamma tables whenever possible.
Use greater precision when changing to linear gamma for compositing against
background and doing rgb-to-gray transformation.
Investigate pre-incremented loop counters and other loop constructions.
Add interpolated method of handling interlacing.
Switch to the simpler zlib (zlib/libpng) license if legally possible.
Extend pngvalid.c to validate more of the libpng transformations.
*/
src/Source/LibPNG/configure view on Meta::CPAN
echo "
There is no \"configure\" script in this distribution (*.zip or *.7z) of
libpng-1.6.16.
Instead, please copy the appropriate makefile for your system from the
\"scripts\" directory. Read the INSTALL file for more details.
Update, July 2004: you can get a \"configure\" based distribution
from the libpng distribution sites. Download the file
libpng-1.6.16.tar.gz, libpng-1.6.16.tar.xz, or libpng-1.6.16.tar.bz2
If the line endings in the files look funny, which is likely to be the
case if you were trying to run \"configure\" on a Linux machine, you may
wish to get the other distribution of libpng. It is available in both
tar.gz/tar.xz (UNIX style line endings, with \"configure\") and .7z/.zip
(DOS style line endings, without \"configure\") formats.
"
src/Source/LibPNG/example.c view on Meta::CPAN
#if 0 /* in case someone actually tries to compile this */
/* example.c - an example of using libpng
* Last changed in libpng 1.6.15 [November 20, 2014]
* Maintained 1998-2014 Glenn Randers-Pehrson
* Maintained 1996, 1997 Andreas Dilger)
* Written 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
* To the extent possible under law, the authors have waived
* all copyright and related or neighboring rights to this file.
* This work is published from: United States.
*/
/* This is an example of how to use libpng to read and write PNG files.
* The file libpng-manual.txt is much more verbose then this. If you have not
* read it, do so first. This was designed to be a starting point of an
* implementation. This is not officially part of libpng, is hereby placed
* in the public domain, and therefore does not require a copyright notice.
*
* This file does not currently compile, because it is missing certain
* parts, like allocating memory to hold an image. You will have to
* supply these parts to get it to compile. For an example of a minimal
* working PNG reader/writer, see pngtest.c, included in this distribution;
* see also the programs in the contrib directory.
*/
/* The simple, but restricted, approach to reading a PNG file or data stream
* just requires two function calls, as in the following complete program.
* Writing a file just needs one function call, so long as the data has an
* appropriate layout.
*
* The following code reads PNG image data from a file and writes it, in a
* potentially new format, to a new file. While this code will compile there is
* minimal (insufficient) error checking; for a more realistic version look at
* contrib/examples/pngtopng.c
*/
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <png.h>
#include <zlib.h>
int main(int argc, const char **argv)
{
if (argc == 3)
{
png_image image; /* The control structure used by libpng */
/* Initialize the 'png_image' structure. */
memset(&image, 0, (sizeof image));
image.version = PNG_IMAGE_VERSION;
/* The first argument is the file to read: */
if (png_image_begin_read_from_file(&image, argv[1]) != 0)
{
png_bytep buffer;
/* Set the format in which to read the PNG file; this code chooses a
* simple sRGB format with a non-associated alpha channel, adequate to
* store most images.
*/
image.format = PNG_FORMAT_RGBA;
/* Now allocate enough memory to hold the image in this format; the
* PNG_IMAGE_SIZE macro uses the information about the image (width,
* height and format) stored in 'image'.
src/Source/LibPNG/example.c view on Meta::CPAN
buffer = malloc(PNG_IMAGE_SIZE(image));
/* If enough memory was available read the image in the desired format
* then write the result out to the new file. 'background' is not
* necessary when reading the image because the alpha channel is
* preserved; if it were to be removed, for example if we requested
* PNG_FORMAT_RGB, then either a solid background color would have to
* be supplied or the output buffer would have to be initialized to the
* actual background of the image.
*
* The fourth argument to png_image_finish_read is the 'row_stride' -
* this is the number of components allocated for the image in each
* row. It has to be at least as big as the value returned by
* PNG_IMAGE_ROW_STRIDE, but if you just allocate space for the
* default, minimum, size using PNG_IMAGE_SIZE as above you can pass
* zero.
*
* The final argument is a pointer to a buffer for the colormap;
* colormaps have exactly the same format as a row of image pixels (so
* you choose what format to make the colormap by setting
* image.format). A colormap is only returned if
* PNG_FORMAT_FLAG_COLORMAP is also set in image.format, so in this
* case NULL is passed as the final argument. If you do want to force
* all images into an index/color-mapped format then you can use:
*
* PNG_IMAGE_COLORMAP_SIZE(image)
*
* to find the maximum size of the colormap in bytes.
*/
if (buffer != NULL &&
png_image_finish_read(&image, NULL/*background*/, buffer,
0/*row_stride*/, NULL/*colormap*/) != 0)
{
/* Now write the image out to the second argument. In the write
* call 'convert_to_8bit' allows 16-bit data to be squashed down to
* 8 bits; this isn't necessary here because the original read was
* to the 8-bit format.
*/
if (png_image_write_to_file(&image, argv[2], 0/*convert_to_8bit*/,
buffer, 0/*row_stride*/, NULL/*colormap*/) != 0)
{
/* The image has been written successfully. */
exit(0);
}
}
else
{
/* Calling png_free_image is optional unless the simplified API was
* not run to completion. In this case if there wasn't enough
* memory for 'buffer' we didn't complete the read, so we must free
* the image:
*/
if (buffer == NULL)
png_free_image(&image);
else
free(buffer);
}
/* Something went wrong reading or writing the image. libpng stores a
* textual message in the 'png_image' structure:
*/
fprintf(stderr, "pngtopng: error: %s\n", image.message);
exit (1);
}
fprintf(stderr, "pngtopng: usage: pngtopng input-file output-file\n");
exit(1);
}
/* That's it ;-) Of course you probably want to do more with PNG files than
* just converting them all to 32-bit RGBA PNG files; you can do that between
* the call to png_image_finish_read and png_image_write_to_file. You can also
* ask for the image data to be presented in a number of different formats. You
* do this by simply changing the 'format' parameter set before allocating the
* buffer.
*
* The format parameter consists of five flags that define various aspects of
* the image, you can simply add these together to get the format or you can use
* one of the predefined macros from png.h (as above):
*
* PNG_FORMAT_FLAG_COLOR: if set the image will have three color components per
* pixel (red, green and blue), if not set the image will just have one
* luminance (grayscale) component.
*
* PNG_FORMAT_FLAG_ALPHA: if set each pixel in the image will have an additional
* alpha value; a linear value that describes the degree the image pixel
* covers (overwrites) the contents of the existing pixel on the display.
*
* PNG_FORMAT_FLAG_LINEAR: if set the components of each pixel will be returned
src/Source/LibPNG/example.c view on Meta::CPAN
* PNG_FORMAT_FLAG_BGR: if set the components of a color pixel will be returned
* in the order blue, then green, then red. If not set the pixel components
* are in the order red, then green, then blue.
*
* PNG_FORMAT_FLAG_AFIRST: if set the alpha channel (if present) precedes the
* color or grayscale components. If not set the alpha channel follows the
* components.
*
* You do not have to read directly from a file. You can read from memory or,
* on systems that support it, from a <stdio.h> FILE*. This is controlled by
* the particular png_image_read_from_ function you call at the start. Likewise
* on write you can write to a FILE* if your system supports it. Check the
* macro PNG_STDIO_SUPPORTED to see if stdio support has been included in your
* libpng build.
*
* If you read 16-bit (PNG_FORMAT_FLAG_LINEAR) data you may need to write it in
* the 8-bit format for display. You do this by setting the convert_to_8bit
* flag to 'true'.
*
* Don't repeatedly convert between the 8-bit and 16-bit forms. There is
* significant data loss when 16-bit data is converted to the 8-bit encoding and
* the current libpng implementation of conversion to 16-bit is also
* significantly lossy. The latter will be fixed in the future, but the former
* is unavoidable - the 8-bit format just doesn't have enough resolution.
*/
/* If your program needs more information from the PNG data it reads, or if you
* need to do more complex transformations, or minimize transformations, on the
* data you read, then you must use one of the several lower level libpng
* interfaces.
*
* All these interfaces require that you do your own error handling - your
* program must be able to arrange for control to return to your own code any
* time libpng encounters a problem. There are several ways to do this, but the
* standard way is to use the ANSI-C (C90) <setjmp.h> interface to establish a
* return point within your own code. You must do this if you do not use the
* simplified interface (above).
*
* The first step is to include the header files you need, including the libpng
* header file. Include any standard headers and feature test macros your
* program requires before including png.h:
*/
#include <png.h>
/* The png_jmpbuf() macro, used in error handling, became available in
* libpng version 1.0.6. If you want to be able to run your code with older
* versions of libpng, you must define the macro yourself (but only if it
* is not already defined by libpng!).
*/
#ifndef png_jmpbuf
# define png_jmpbuf(png_ptr) ((png_ptr)->png_jmpbuf)
#endif
/* Check to see if a file is a PNG file using png_sig_cmp(). png_sig_cmp()
* returns zero if the image is a PNG and nonzero if it isn't a PNG.
*
* The function check_if_png() shown here, but not used, returns nonzero (true)
* if the file can be opened and is a PNG, 0 (false) otherwise.
*
* If this call is successful, and you are going to keep the file open,
* you should call png_set_sig_bytes(png_ptr, PNG_BYTES_TO_CHECK); once
* you have created the png_ptr, so that libpng knows your application
* has read that many bytes from the start of the file. Make sure you
* don't call png_set_sig_bytes() with more than 8 bytes read or give it
* an incorrect number of bytes read, or you will either have read too
* many bytes (your fault), or you are telling libpng to read the wrong
* number of magic bytes (also your fault).
*
* Many applications already read the first 2 or 4 bytes from the start
* of the image to determine the file type, so it would be easiest just
* to pass the bytes to png_sig_cmp() or even skip that if you know
* you have a PNG file, and call png_set_sig_bytes().
*/
#define PNG_BYTES_TO_CHECK 4
int check_if_png(char *file_name, FILE **fp)
{
char buf[PNG_BYTES_TO_CHECK];
/* Open the prospective PNG file. */
if ((*fp = fopen(file_name, "rb")) == NULL)
return 0;
/* Read in some of the signature bytes */
if (fread(buf, 1, PNG_BYTES_TO_CHECK, *fp) != PNG_BYTES_TO_CHECK)
return 0;
/* Compare the first PNG_BYTES_TO_CHECK bytes of the signature.
Return nonzero (true) if they match */
return(!png_sig_cmp(buf, (png_size_t)0, PNG_BYTES_TO_CHECK));
}
/* Read a PNG file. You may want to return an error code if the read
* fails (depending upon the failure). There are two "prototypes" given
* here - one where we are given the filename, and we need to open the
* file, and the other where we are given an open file (possibly with
* some or all of the magic bytes read - see comments above).
*/
#ifdef open_file /* prototype 1 */
void read_png(char *file_name) /* We need to open the file */
{
png_structp png_ptr;
png_infop info_ptr;
unsigned int sig_read = 0;
png_uint_32 width, height;
int bit_depth, color_type, interlace_type;
FILE *fp;
if ((fp = fopen(file_name, "rb")) == NULL)
return (ERROR);
#else no_open_file /* prototype 2 */
void read_png(FILE *fp, unsigned int sig_read) /* File is already open */
{
png_structp png_ptr;
png_infop info_ptr;
png_uint_32 width, height;
int bit_depth, color_type, interlace_type;
#endif no_open_file /* Only use one prototype! */
/* Create and initialize the png_struct with the desired error handler
* functions. If you want to use the default stderr and longjump method,
* you can supply NULL for the last three parameters. We also supply the
* the compiler header file version, so that we know if the application
* was compiled with a compatible version of the library. REQUIRED
*/
png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
png_voidp user_error_ptr, user_error_fn, user_warning_fn);
if (png_ptr == NULL)
{
fclose(fp);
return (ERROR);
}
/* Allocate/initialize the memory for image information. REQUIRED. */
info_ptr = png_create_info_struct(png_ptr);
if (info_ptr == NULL)
{
fclose(fp);
png_destroy_read_struct(&png_ptr, NULL, NULL);
return (ERROR);
}
/* Set error handling if you are using the setjmp/longjmp method (this is
* the normal method of doing things with libpng). REQUIRED unless you
* set up your own error handlers in the png_create_read_struct() earlier.
*/
if (setjmp(png_jmpbuf(png_ptr)))
{
/* Free all of the memory associated with the png_ptr and info_ptr */
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
fclose(fp);
/* If we get here, we had a problem reading the file */
return (ERROR);
}
/* One of the following I/O initialization methods is REQUIRED */
#ifdef streams /* PNG file I/O method 1 */
/* Set up the input control if you are using standard C streams */
png_init_io(png_ptr, fp);
#else no_streams /* PNG file I/O method 2 */
/* If you are using replacement read functions, instead of calling
* png_init_io() here you would call:
*/
png_set_read_fn(png_ptr, (void *)user_io_ptr, user_read_fn);
/* where user_io_ptr is a structure you want available to the callbacks */
#endif no_streams /* Use only one I/O method! */
/* If we have already read some of the signature */
png_set_sig_bytes(png_ptr, sig_read);
#ifdef hilevel
/*
* If you have enough memory to read in the entire image at once,
* and you need to specify only transforms that can be controlled
* with one of the PNG_TRANSFORM_* bits (this presently excludes
* quantizing, filling, setting background, and doing gamma
* adjustment), then you can read the entire image (including
* pixels) into the info structure with this call:
*/
png_read_png(png_ptr, info_ptr, png_transforms, NULL);
#else
/* OK, you're doing it the hard way, with the lower-level functions */
/* The call to png_read_info() gives us all of the information from the
* PNG file before the first IDAT (image data chunk). REQUIRED
*/
png_read_info(png_ptr, info_ptr);
png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
&interlace_type, NULL, NULL);
/* Set up the data transformations you want. Note that these are all
* optional. Only call them if you want/need them. Many of the
* transformations only work on specific types of images, and many
* are mutually exclusive.
*/
/* Tell libpng to strip 16 bit/color files down to 8 bits/color.
* Use accurate scaling if it's available, otherwise just chop off the
* low byte.
*/
#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
png_set_scale_16(png_ptr);
#else
png_set_strip_16(png_ptr);
#endif
/* Strip alpha bytes from the input data without combining with the
* background (not recommended).
*/
png_set_strip_alpha(png_ptr);
/* Extract multiple pixels with bit depths of 1, 2, and 4 from a single
* byte into separate bytes (useful for paletted and grayscale images).
*/
png_set_packing(png_ptr);
/* Change the order of packed pixels to least significant bit first
* (not useful if you are using png_set_packing). */
png_set_packswap(png_ptr);
/* Expand paletted colors into true RGB triplets */
if (color_type == PNG_COLOR_TYPE_PALETTE)
png_set_palette_to_rgb(png_ptr);
/* Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel */
if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
png_set_expand_gray_1_2_4_to_8(png_ptr);
/* Expand paletted or RGB images with transparency to full alpha channels
* so the data will be available as RGBA quartets.
*/
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS) != 0)
png_set_tRNS_to_alpha(png_ptr);
/* Set the background color to draw transparent and alpha images over.
* It is possible to set the red, green, and blue components directly
* for paletted images instead of supplying a palette index. Note that
* even if the PNG file supplies a background, you are not required to
* use it - you should use the (solid) application background if it has one.
*/
png_color_16 my_background, *image_background;
if (png_get_bKGD(png_ptr, info_ptr, &image_background) != 0)
png_set_background(png_ptr, image_background,
PNG_BACKGROUND_GAMMA_FILE, 1, 1.0);
else
png_set_background(png_ptr, &my_background,
PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
/* Some suggestions as to how to get a screen gamma value
*
* Note that screen gamma is the display_exponent, which includes
* the CRT_exponent and any correction for viewing conditions
*/
if (/* We have a user-defined screen gamma value */)
{
screen_gamma = user-defined screen_gamma;
src/Source/LibPNG/example.c view on Meta::CPAN
screen_gamma = atof(gamma_str);
}
/* If we don't have another value */
else
{
screen_gamma = PNG_DEFAULT_sRGB; /* A good guess for a PC monitor
in a dimly lit room */
screen_gamma = PNG_GAMMA_MAC_18 or 1.0; /* Good guesses for Mac systems */
}
/* Tell libpng to handle the gamma conversion for you. The final call
* is a good guess for PC generated images, but it should be configurable
* by the user at run time by the user. It is strongly suggested that
* your application support gamma correction.
*/
int intent;
if (png_get_sRGB(png_ptr, info_ptr, &intent) != 0)
png_set_gamma(png_ptr, screen_gamma, PNG_DEFAULT_sRGB);
else
{
double image_gamma;
if (png_get_gAMA(png_ptr, info_ptr, &image_gamma) != 0)
png_set_gamma(png_ptr, screen_gamma, image_gamma);
else
png_set_gamma(png_ptr, screen_gamma, 0.45455);
}
#ifdef PNG_READ_QUANTIZE_SUPPORTED
/* Quantize RGB files down to 8 bit palette or reduce palettes
* to the number of colors available on your screen.
*/
if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
{
int num_palette;
png_colorp palette;
/* This reduces the image to the application supplied palette */
if (/* We have our own palette */)
{
/* An array of colors to which the image should be quantized */
png_color std_color_cube[MAX_SCREEN_COLORS];
png_set_quantize(png_ptr, std_color_cube, MAX_SCREEN_COLORS,
MAX_SCREEN_COLORS, NULL, 0);
}
/* This reduces the image to the palette supplied in the file */
else if (png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette) != 0)
{
png_uint_16p histogram = NULL;
png_get_hIST(png_ptr, info_ptr, &histogram);
png_set_quantize(png_ptr, palette, num_palette,
max_screen_colors, histogram, 0);
}
}
#endif /* READ_QUANTIZE */
/* Invert monochrome files to have 0 as white and 1 as black */
png_set_invert_mono(png_ptr);
/* If you want to shift the pixel values from the range [0,255] or
* [0,65535] to the original [0,7] or [0,31], or whatever range the
* colors were originally in:
*/
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT) != 0)
{
png_color_8p sig_bit_p;
png_get_sBIT(png_ptr, info_ptr, &sig_bit_p);
png_set_shift(png_ptr, sig_bit_p);
}
/* Flip the RGB pixels to BGR (or RGBA to BGRA) */
if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
png_set_bgr(png_ptr);
/* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */
png_set_swap_alpha(png_ptr);
/* Swap bytes of 16 bit files to least significant byte first */
png_set_swap(png_ptr);
/* Add filler (or alpha) byte (before/after each RGB triplet) */
png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER);
#ifdef PNG_READ_INTERLACING_SUPPORTED
/* Turn on interlace handling. REQUIRED if you are not using
* png_read_image(). To see how to handle interlacing passes,
* see the png_read_row() method below:
*/
number_passes = png_set_interlace_handling(png_ptr);
#else
number_passes = 1;
#endif /* READ_INTERLACING */
/* Optional call to gamma correct and add the background to the palette
* and update info structure. REQUIRED if you are expecting libpng to
* update the palette for you (ie you selected such a transform above).
*/
png_read_update_info(png_ptr, info_ptr);
/* Allocate the memory to hold the image using the fields of info_ptr. */
/* The easiest way to read the image: */
png_bytep row_pointers[height];
/* Clear the pointer array */
for (row = 0; row < height; row++)
row_pointers[row] = NULL;
for (row = 0; row < height; row++)
row_pointers[row] = png_malloc(png_ptr, png_get_rowbytes(png_ptr,
info_ptr));
/* Now it's time to read the image. One of these methods is REQUIRED */
#ifdef entire /* Read the entire image in one go */
png_read_image(png_ptr, row_pointers);
#else no_entire /* Read the image one or more scanlines at a time */
/* The other way to read images - deal with interlacing: */
for (pass = 0; pass < number_passes; pass++)
{
#ifdef single /* Read the image a single row at a time */
for (y = 0; y < height; y++)
{
png_read_rows(png_ptr, &row_pointers[y], NULL, 1);
}
#else no_single /* Read the image several rows at a time */
for (y = 0; y < height; y += number_of_rows)
{
#ifdef sparkle /* Read the image using the "sparkle" effect. */
png_read_rows(png_ptr, &row_pointers[y], NULL,
number_of_rows);
#else no_sparkle /* Read the image using the "rectangle" effect */
png_read_rows(png_ptr, NULL, &row_pointers[y],
number_of_rows);
#endif no_sparkle /* Use only one of these two methods */
}
/* If you want to display the image after every pass, do so here */
#endif no_single /* Use only one of these two methods */
}
#endif no_entire /* Use only one of these two methods */
/* Read rest of file, and get additional chunks in info_ptr - REQUIRED */
png_read_end(png_ptr, info_ptr);
#endif hilevel
/* At this point you have read the entire image */
/* Clean up after the read, and free any memory allocated - REQUIRED */
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
/* Close the file */
fclose(fp);
/* That's it */
return (OK);
}
/* Progressively read a file */
int
initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr)
{
/* Create and initialize the png_struct with the desired error handler
* functions. If you want to use the default stderr and longjump method,
* you can supply NULL for the last three parameters. We also check that
* the library version is compatible in case we are using dynamically
* linked libraries.
*/
*png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
png_voidp user_error_ptr, user_error_fn, user_warning_fn);
if (*png_ptr == NULL)
{
*info_ptr = NULL;
return (ERROR);
}
*info_ptr = png_create_info_struct(png_ptr);
if (*info_ptr == NULL)
{
png_destroy_read_struct(png_ptr, info_ptr, NULL);
return (ERROR);
}
if (setjmp(png_jmpbuf((*png_ptr))))
{
png_destroy_read_struct(png_ptr, info_ptr, NULL);
return (ERROR);
}
/* This one's new. You will need to provide all three
* function callbacks, even if you aren't using them all.
* If you aren't using all functions, you can specify NULL
* parameters. Even when all three functions are NULL,
* you need to call png_set_progressive_read_fn().
* These functions shouldn't be dependent on global or
* static variables if you are decoding several images
* simultaneously. You should store stream specific data
* in a separate struct, given as the second parameter,
* and retrieve the pointer from inside the callbacks using
* the function png_get_progressive_ptr(png_ptr).
*/
png_set_progressive_read_fn(*png_ptr, (void *)stream_data,
info_callback, row_callback, end_callback);
return (OK);
}
int
process_data(png_structp *png_ptr, png_infop *info_ptr,
png_bytep buffer, png_uint_32 length)
{
if (setjmp(png_jmpbuf((*png_ptr))))
{
/* Free the png_ptr and info_ptr memory on error */
png_destroy_read_struct(png_ptr, info_ptr, NULL);
return (ERROR);
}
/* This one's new also. Simply give it chunks of data as
* they arrive from the data stream (in order, of course).
* On segmented machines, don't give it any more than 64K.
* The library seems to run fine with sizes of 4K, although
* you can give it much less if necessary (I assume you can
* give it chunks of 1 byte, but I haven't tried with less
* than 256 bytes yet). When this function returns, you may
* want to display any rows that were generated in the row
* callback, if you aren't already displaying them there.
*/
png_process_data(*png_ptr, *info_ptr, buffer, length);
return (OK);
}
info_callback(png_structp png_ptr, png_infop info)
{
/* Do any setup here, including setting any of the transformations
* mentioned in the Reading PNG files section. For now, you _must_
* call either png_start_read_image() or png_read_update_info()
* after all the transformations are set (even if you don't set
* any). You may start getting rows before png_process_data()
* returns, so this is your last chance to prepare for that.
*/
}
row_callback(png_structp png_ptr, png_bytep new_row,
png_uint_32 row_num, int pass)
{
/*
* This function is called for every row in the image. If the
* image is interlaced, and you turned on the interlace handler,
* this function will be called for every row in every pass.
*
* In this function you will receive a pointer to new row data from
* libpng called new_row that is to replace a corresponding row (of
* the same data format) in a buffer allocated by your application.
*
* The new row data pointer "new_row" may be NULL, indicating there is
* no new data to be replaced (in cases of interlace loading).
*
* If new_row is not NULL then you need to call
* png_progressive_combine_row() to replace the corresponding row as
* shown below:
*/
/* Get pointer to corresponding row in our
* PNG read buffer.
*/
png_bytep old_row = ((png_bytep *)our_data)[row_num];
#ifdef PNG_READ_INTERLACING_SUPPORTED
/* If both rows are allocated then copy the new row
* data to the corresponding row data.
*/
if ((old_row != NULL) && (new_row != NULL))
png_progressive_combine_row(png_ptr, old_row, new_row);
/*
* The rows and passes are called in order, so you don't really
* need the row_num and pass, but I'm supplying them because it
* may make your life easier.
*
* For the non-NULL rows of interlaced images, you must call
* png_progressive_combine_row() passing in the new row and the
* old row, as demonstrated above. You can call this function for
* NULL rows (it will just return) and for non-interlaced images
* (it just does the memcpy for you) if it will make the code
* easier. Thus, you can just do this for all cases:
*/
png_progressive_combine_row(png_ptr, old_row, new_row);
/* where old_row is what was displayed for previous rows. Note
* that the first pass (pass == 0 really) will completely cover
* the old row, so the rows do not have to be initialized. After
* the first pass (and only for interlaced images), you will have
* to pass the current row as new_row, and the function will combine
* the old row and the new row.
*/
#endif /* READ_INTERLACING */
}
end_callback(png_structp png_ptr, png_infop info)
{
/* This function is called when the whole image has been read,
* including any chunks after the image (up to and including
* the IEND). You will usually have the same info chunk as you
* had in the header, although some data may have been added
* to the comments and time fields.
*
* Most people won't do much here, perhaps setting a flag that
* marks the image as finished.
*/
}
/* Write a png file */
void write_png(char *file_name /* , ... other image information ... */)
{
FILE *fp;
png_structp png_ptr;
png_infop info_ptr;
png_colorp palette;
/* Open the file */
fp = fopen(file_name, "wb");
if (fp == NULL)
return (ERROR);
/* Create and initialize the png_struct with the desired error handler
* functions. If you want to use the default stderr and longjump method,
* you can supply NULL for the last three parameters. We also check that
* the library version is compatible with the one used at compile time,
* in case we are using dynamically linked libraries. REQUIRED.
*/
png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
png_voidp user_error_ptr, user_error_fn, user_warning_fn);
if (png_ptr == NULL)
{
fclose(fp);
return (ERROR);
}
/* Allocate/initialize the image information data. REQUIRED */
info_ptr = png_create_info_struct(png_ptr);
if (info_ptr == NULL)
{
fclose(fp);
png_destroy_write_struct(&png_ptr, NULL);
return (ERROR);
}
/* Set error handling. REQUIRED if you aren't supplying your own
* error handling functions in the png_create_write_struct() call.
*/
if (setjmp(png_jmpbuf(png_ptr)))
{
/* If we get here, we had a problem writing the file */
fclose(fp);
png_destroy_write_struct(&png_ptr, &info_ptr);
return (ERROR);
}
/* One of the following I/O initialization functions is REQUIRED */
#ifdef streams /* I/O initialization method 1 */
/* Set up the output control if you are using standard C streams */
png_init_io(png_ptr, fp);
#else no_streams /* I/O initialization method 2 */
/* If you are using replacement write functions, instead of calling
* png_init_io() here you would call
*/
png_set_write_fn(png_ptr, (void *)user_io_ptr, user_write_fn,
user_IO_flush_function);
/* where user_io_ptr is a structure you want available to the callbacks */
#endif no_streams /* Only use one initialization method */
#ifdef hilevel
/* This is the easy way. Use it if you already have all the
* image info living in the structure. You could "|" many
* PNG_TRANSFORM flags into the png_transforms integer here.
*/
png_write_png(png_ptr, info_ptr, png_transforms, NULL);
#else
/* This is the hard way */
/* Set the image information here. Width and height are up to 2^31,
* bit_depth is one of 1, 2, 4, 8, or 16, but valid values also depend on
* the color_type selected. color_type is one of PNG_COLOR_TYPE_GRAY,
* PNG_COLOR_TYPE_GRAY_ALPHA, PNG_COLOR_TYPE_PALETTE, PNG_COLOR_TYPE_RGB,
* or PNG_COLOR_TYPE_RGB_ALPHA. interlace is either PNG_INTERLACE_NONE or
* PNG_INTERLACE_ADAM7, and the compression_type and filter_type MUST
* currently be PNG_COMPRESSION_TYPE_BASE and PNG_FILTER_TYPE_BASE. REQUIRED
*/
png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, PNG_COLOR_TYPE_???,
PNG_INTERLACE_????, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
/* Set the palette if there is one. REQUIRED for indexed-color images */
palette = (png_colorp)png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH
* (sizeof (png_color)));
/* ... Set palette colors ... */
png_set_PLTE(png_ptr, info_ptr, palette, PNG_MAX_PALETTE_LENGTH);
/* You must not free palette here, because png_set_PLTE only makes a link to
* the palette that you malloced. Wait until you are about to destroy
* the png structure.
*/
/* Optional significant bit (sBIT) chunk */
png_color_8 sig_bit;
/* If we are dealing with a grayscale image then */
sig_bit.gray = true_bit_depth;
/* Otherwise, if we are dealing with a color image then */
sig_bit.red = true_red_bit_depth;
sig_bit.green = true_green_bit_depth;
sig_bit.blue = true_blue_bit_depth;
/* If the image has an alpha channel then */
sig_bit.alpha = true_alpha_bit_depth;
png_set_sBIT(png_ptr, info_ptr, &sig_bit);
/* Optional gamma chunk is strongly suggested if you have any guess
* as to the correct gamma of the image.
*/
png_set_gAMA(png_ptr, info_ptr, gamma);
/* Optionally write comments into the image */
{
png_text text_ptr[3];
char key0[]="Title";
char text0[]="Mona Lisa";
text_ptr[0].key = key0;
text_ptr[0].text = text0;
text_ptr[0].compression = PNG_TEXT_COMPRESSION_NONE;
text_ptr[0].itxt_length = 0;
text_ptr[0].lang = NULL;
text_ptr[0].lang_key = NULL;
src/Source/LibPNG/example.c view on Meta::CPAN
char key2[]="Description";
char text2[]="<long text>";
text_ptr[2].key = key2;
text_ptr[2].text = text2;
text_ptr[2].compression = PNG_TEXT_COMPRESSION_zTXt;
text_ptr[2].itxt_length = 0;
text_ptr[2].lang = NULL;
text_ptr[2].lang_key = NULL;
png_set_text(write_ptr, write_info_ptr, text_ptr, 3);
}
/* Other optional chunks like cHRM, bKGD, tRNS, tIME, oFFs, pHYs */
/* Note that if sRGB is present the gAMA and cHRM chunks must be ignored
* on read and, if your application chooses to write them, they must
* be written in accordance with the sRGB profile
*/
/* Write the file header information. REQUIRED */
png_write_info(png_ptr, info_ptr);
/* If you want, you can write the info in two steps, in case you need to
* write your private chunk ahead of PLTE:
*
* png_write_info_before_PLTE(write_ptr, write_info_ptr);
* write_my_chunk();
* png_write_info(png_ptr, info_ptr);
*
* However, given the level of known- and unknown-chunk support in 1.2.0
* and up, this should no longer be necessary.
*/
/* Once we write out the header, the compression type on the text
* chunk gets changed to PNG_TEXT_COMPRESSION_NONE_WR or
* PNG_TEXT_COMPRESSION_zTXt_WR, so it doesn't get written out again
* at the end.
*/
/* Set up the transformations you want. Note that these are
* all optional. Only call them if you want them.
*/
/* Invert monochrome pixels */
png_set_invert_mono(png_ptr);
/* Shift the pixels up to a legal bit depth and fill in
* as appropriate to correctly scale the image.
*/
png_set_shift(png_ptr, &sig_bit);
/* Pack pixels into bytes */
png_set_packing(png_ptr);
/* Swap location of alpha bytes from ARGB to RGBA */
png_set_swap_alpha(png_ptr);
/* Get rid of filler (OR ALPHA) bytes, pack XRGB/RGBX/ARGB/RGBA into
* RGB (4 channels -> 3 channels). The second parameter is not used.
*/
png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
/* Flip BGR pixels to RGB */
png_set_bgr(png_ptr);
/* Swap bytes of 16-bit files to most significant byte first */
png_set_swap(png_ptr);
/* Swap bits of 1, 2, 4 bit packed pixel formats */
png_set_packswap(png_ptr);
/* Turn on interlace handling if you are not using png_write_image() */
if (interlacing != 0)
number_passes = png_set_interlace_handling(png_ptr);
else
number_passes = 1;
/* The easiest way to write the image (you may have a different memory
* layout, however, so choose what fits your needs best). You need to
* use the first method if you aren't handling interlacing yourself.
*/
png_uint_32 k, height, width;
/* In this example, "image" is a one-dimensional array of bytes */
png_byte image[height*width*bytes_per_pixel];
png_bytep row_pointers[height];
if (height > PNG_UINT_32_MAX/(sizeof (png_bytep)))
png_error (png_ptr, "Image is too tall to process in memory");
/* Set up pointers into your "image" byte array */
for (k = 0; k < height; k++)
row_pointers[k] = image + k*width*bytes_per_pixel;
/* One of the following output methods is REQUIRED */
#ifdef entire /* Write out the entire image data in one call */
png_write_image(png_ptr, row_pointers);
/* The other way to write the image - deal with interlacing */
#else no_entire /* Write out the image data by one or more scanlines */
/* The number of passes is either 1 for non-interlaced images,
* or 7 for interlaced images.
*/
for (pass = 0; pass < number_passes; pass++)
{
/* Write a few rows at a time. */
png_write_rows(png_ptr, &row_pointers[first_row], number_of_rows);
/* If you are only writing one row at a time, this works */
for (y = 0; y < height; y++)
png_write_rows(png_ptr, &row_pointers[y], 1);
}
#endif no_entire /* Use only one output method */
/* You can write optional chunks like tEXt, zTXt, and tIME at the end
* as well. Shouldn't be necessary in 1.2.0 and up as all the public
* chunks are supported and you can use png_set_unknown_chunks() to
* register unknown chunks into the info structure to be written out.
*/
/* It is REQUIRED to call this to finish writing the rest of the file */
png_write_end(png_ptr, info_ptr);
#endif hilevel
/* If you png_malloced a palette, free it here (don't free info_ptr->palette,
* as recommended in versions 1.0.5m and earlier of this example; if
* libpng mallocs info_ptr->palette, libpng will free it). If you
* allocated it with malloc() instead of png_malloc(), use free() instead
* of png_free().
*/
png_free(png_ptr, palette);
palette = NULL;
/* Similarly, if you png_malloced any data that you passed in with
* png_set_something(), such as a hist or trans array, free it here,
* when you can be sure that libpng is through with it.
*/
png_free(png_ptr, trans);
trans = NULL;
/* Whenever you use png_free() it is a good idea to set the pointer to
* NULL in case your application inadvertently tries to png_free() it
* again. When png_free() sees a NULL it returns without action, thus
* avoiding the double-free security problem.
*/
/* Clean up after the write, and free any memory allocated */
png_destroy_write_struct(&png_ptr, &info_ptr);
/* Close the file */
fclose(fp);
/* That's it */
return (OK);
}
#endif /* if 0 */
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
libpng-manual.txt - A description on how to use and modify libpng
libpng version 1.6.16 - December 22, 2014
Updated and distributed by Glenn Randers-Pehrson
<glennrp at users.sourceforge.net>
Copyright (c) 1998-2014 Glenn Randers-Pehrson
This document is released under the libpng license.
For conditions of distribution and use, see the disclaimer
and license in png.h
Based on:
libpng versions 0.97, January 1998, through 1.6.16 - December 22, 2014
Updated and distributed by Glenn Randers-Pehrson
Copyright (c) 1998-2014 Glenn Randers-Pehrson
libpng 1.0 beta 6 - version 0.96 - May 28, 1997
Updated and distributed by Andreas Dilger
Copyright (c) 1996, 1997 Andreas Dilger
libpng 1.0 beta 2 - version 0.88 - January 26, 1996
For conditions of distribution and use, see copyright
notice in png.h. Copyright (c) 1995, 1996 Guy Eric
Schalnat, Group 42, Inc.
Updated/rewritten per request in the libpng FAQ
Copyright (c) 1995, 1996 Frank J. T. Wojcik
December 18, 1995 & January 20, 1996
TABLE OF CONTENTS
I. Introduction
II. Structures
III. Reading
IV. Writing
V. Simplified API
VI. Modifying/Customizing libpng
VII. MNG support
VIII. Changes to Libpng from version 0.88
IX. Changes to Libpng from version 1.0.x to 1.2.x
X. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x
XI. Changes to Libpng from version 1.4.x to 1.5.x
XII. Changes to Libpng from version 1.5.x to 1.6.x
XIII. Detecting libpng
XIV. Source code repository
XV. Coding style
XVI. Y2K Compliance in libpng
I. Introduction
This file describes how to use and modify the PNG reference library
(known as libpng) for your own use. In addition to this
file, example.c is a good starting point for using the library, as
it is heavily commented and should include everything most people
will need. We assume that libpng is already installed; see the
INSTALL file for instructions on how to configure and install libpng.
For examples of libpng usage, see the files "example.c", "pngtest.c",
and the files in the "contrib" directory, all of which are included in
the libpng distribution.
Libpng was written as a companion to the PNG specification, as a way
of reducing the amount of time and effort it takes to support the PNG
file format in application programs.
The PNG specification (second edition), November 2003, is available as
a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2004 (E)) at
<http://www.w3.org/TR/2003/REC-PNG-20031110/
The W3C and ISO documents have identical technical content.
The PNG-1.2 specification is available at
<http://www.libpng.org/pub/png/documents/>. It is technically equivalent
to the PNG specification (second edition) but has some additional material.
The PNG-1.0 specification is available
as RFC 2083 <http://www.libpng.org/pub/png/documents/> and as a
W3C Recommendation <http://www.w3.org/TR/REC.png.html>.
Some additional chunks are described in the special-purpose public chunks
documents at <http://www.libpng.org/pub/png/documents/>.
Other information
about PNG, and the latest version of libpng, can be found at the PNG home
page, <http://www.libpng.org/pub/png/>.
Most users will not have to modify the library significantly; advanced
users may want to modify it more. All attempts were made to make it as
complete as possible, while keeping the code easy to understand.
Currently, this library only supports C. Support for other languages
is being considered.
Libpng has been designed to handle multiple sessions at one time,
to be easily modifiable, to be portable to the vast majority of
machines (ANSI, K&R, 16-, 32-, and 64-bit) available, and to be easy
to use. The ultimate goal of libpng is to promote the acceptance of
the PNG file format in whatever way possible. While there is still
work to be done (see the TODO file), libpng should cover the
majority of the needs of its users.
Libpng uses zlib for its compression and decompression of PNG files.
Further information about zlib, and the latest version of zlib, can
be found at the zlib home page, <http://www.info-zip.org/pub/infozip/zlib/>.
The zlib compression utility is a general purpose utility that is
useful for more than PNG files, and can be used without libpng.
See the documentation delivered with zlib for more details.
You can usually find the source files for the zlib utility wherever you
find the libpng source files.
Libpng is thread safe, provided the threads are using different
instances of the structures. Each thread should have its own
png_struct and png_info instances, and thus its own image.
Libpng does not protect itself against two threads using the
same instance of a structure.
II. Structures
There are two main structures that are important to libpng, png_struct
and png_info. Both are internal structures that are no longer exposed
in the libpng interface (as of libpng 1.5.0).
The png_info structure is designed to provide information about the
PNG file. At one time, the fields of png_info were intended to be
directly accessible to the user. However, this tended to cause problems
with applications using dynamically loaded libraries, and as a result
a set of interface functions for png_info (the png_get_*() and png_set_*()
functions) was developed, and direct access to the png_info fields was
deprecated..
The png_struct structure is the object used by the library to decode a
single image. As of 1.5.0 this structure is also not exposed.
Almost all libpng APIs require a pointer to a png_struct as the first argument.
Many (in particular the png_set and png_get APIs) also require a pointer
to png_info as the second argument. Some application visible macros
defined in png.h designed for basic data access (reading and writing
integers in the PNG format) don't take a png_info pointer, but it's almost
always safe to assume that a (png_struct*) has to be passed to call an API
function.
You can have more than one png_info structure associated with an image,
as illustrated in pngtest.c, one for information valid prior to the
IDAT chunks and another (called "end_info" below) for things after them.
The png.h header file is an invaluable reference for programming with libpng.
And while I'm on the topic, make sure you include the libpng header file:
#include <png.h>
and also (as of libpng-1.5.0) the zlib header file, if you need it:
#include <zlib.h>
Types
The png.h header file defines a number of integral types used by the
APIs. Most of these are fairly obvious; for example types corresponding
to integers of particular sizes and types for passing color values.
One exception is how non-integral numbers are handled. For application
convenience most APIs that take such numbers have C (double) arguments;
however, internally PNG, and libpng, use 32 bit signed integers and encode
the value by multiplying by 100,000. As of libpng 1.5.0 a convenience
macro PNG_FP_1 is defined in png.h along with a type (png_fixed_point)
which is simply (png_int_32).
All APIs that take (double) arguments also have a matching API that
takes the corresponding fixed point integer arguments. The fixed point
API has the same name as the floating point one with "_fixed" appended.
The actual range of values permitted in the APIs is frequently less than
the full range of (png_fixed_point) (-21474 to +21474). When APIs require
a non-negative argument the type is recorded as png_uint_32 above. Consult
the header file and the text below for more information.
Special care must be take with sCAL chunk handling because the chunk itself
uses non-integral values encoded as strings containing decimal floating point
numbers. See the comments in the header file.
Configuration
The main header file function declarations are frequently protected by C
preprocessing directives of the form:
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
declare-function
#endif
...
#ifdef PNG_feature_SUPPORTED
use-function
#endif
The library can be built without support for these APIs, although a
standard build will have all implemented APIs. Application programs
should check the feature macros before using an API for maximum
portability. From libpng 1.5.0 the feature macros set during the build
of libpng are recorded in the header file "pnglibconf.h" and this file
is always included by png.h.
If you don't need to change the library configuration from the default, skip to
the next section ("Reading").
Notice that some of the makefiles in the 'scripts' directory and (in 1.5.0) all
of the build project files in the 'projects' directory simply copy
scripts/pnglibconf.h.prebuilt to pnglibconf.h. This means that these build
systems do not permit easy auto-configuration of the library - they only
support the default configuration.
The easiest way to make minor changes to the libpng configuration when
auto-configuration is supported is to add definitions to the command line
using (typically) CPPFLAGS. For example:
CPPFLAGS=-DPNG_NO_FLOATING_ARITHMETIC
will change the internal libpng math implementation for gamma correction and
other arithmetic calculations to fixed point, avoiding the need for fast
floating point support. The result can be seen in the generated pnglibconf.h -
make sure it contains the changed feature macro setting.
If you need to make more extensive configuration changes - more than one or two
feature macro settings - you can either add -DPNG_USER_CONFIG to the build
command line and put a list of feature macro settings in pngusr.h or you can set
DFA_XTRA (a makefile variable) to a file containing the same information in the
form of 'option' settings.
A. Changing pnglibconf.h
A variety of methods exist to build libpng. Not all of these support
reconfiguration of pnglibconf.h. To reconfigure pnglibconf.h it must either be
rebuilt from scripts/pnglibconf.dfa using awk or it must be edited by hand.
Hand editing is achieved by copying scripts/pnglibconf.h.prebuilt to
pnglibconf.h and changing the lines defining the supported features, paying
very close attention to the 'option' information in scripts/pnglibconf.dfa
that describes those features and their requirements. This is easy to get
wrong.
B. Configuration using DFA_XTRA
Rebuilding from pnglibconf.dfa is easy if a functioning 'awk', or a later
variant such as 'nawk' or 'gawk', is available. The configure build will
automatically find an appropriate awk and build pnglibconf.h.
The scripts/pnglibconf.mak file contains a set of make rules for doing the
same thing if configure is not used, and many of the makefiles in the scripts
directory use this approach.
When rebuilding simply write a new file containing changed options and set
DFA_XTRA to the name of this file. This causes the build to append the new file
to the end of scripts/pnglibconf.dfa. The pngusr.dfa file should contain lines
of the following forms:
everything = off
This turns all optional features off. Include it at the start of pngusr.dfa to
make it easier to build a minimal configuration. You will need to turn at least
some features on afterward to enable either reading or writing code, or both.
option feature on
option feature off
Enable or disable a single feature. This will automatically enable other
features required by a feature that is turned on or disable other features that
require a feature which is turned off. Conflicting settings will cause an error
message to be emitted by awk.
setting feature default value
Changes the default value of setting 'feature' to 'value'. There are a small
number of settings listed at the top of pnglibconf.h, they are documented in the
source code. Most of these values have performance implications for the library
but most of them have no visible effect on the API. Some can also be overridden
from the API.
This method of building a customized pnglibconf.h is illustrated in
contrib/pngminim/*. See the "$(PNGCONF):" target in the makefile and
pngusr.dfa in these directories.
C. Configuration using PNG_USER_CONFIG
If -DPNG_USER_CONFIG is added to the CPPFLAGS when pnglibconf.h is built,
the file pngusr.h will automatically be included before the options in
scripts/pnglibconf.dfa are processed. Your pngusr.h file should contain only
macro definitions turning features on or off or setting settings.
Apart from the global setting "everything = off" all the options listed above
can be set using macros in pngusr.h:
#define PNG_feature_SUPPORTED
is equivalent to:
option feature on
#define PNG_NO_feature
is equivalent to:
option feature off
#define PNG_feature value
is equivalent to:
setting feature default value
Notice that in both cases, pngusr.dfa and pngusr.h, the contents of the
pngusr file you supply override the contents of scripts/pnglibconf.dfa
If confusing or incomprehensible behavior results it is possible to
examine the intermediate file pnglibconf.dfn to find the full set of
dependency information for each setting and option. Simply locate the
feature in the file and read the C comments that precede it.
This method is also illustrated in the contrib/pngminim/* makefiles and
pngusr.h.
III. Reading
We'll now walk you through the possible functions to call when reading
in a PNG file sequentially, briefly explaining the syntax and purpose
of each one. See example.c and png.h for more detail. While
progressive reading is covered in the next section, you will still
need some of the functions discussed in this section to read a PNG
file.
Setup
You will want to do the I/O initialization(*) before you get into libpng,
so if it doesn't work, you don't have much to undo. Of course, you
will also want to insure that you are, in fact, dealing with a PNG
file. Libpng provides a simple check to see if a file is a PNG file.
To use it, pass in the first 1 to 8 bytes of the file to the function
png_sig_cmp(), and it will return 0 (false) if the bytes match the
corresponding bytes of the PNG signature, or nonzero (true) otherwise.
Of course, the more bytes you pass in, the greater the accuracy of the
prediction.
If you are intending to keep the file pointer open for use in libpng,
you must ensure you don't read more than 8 bytes from the beginning
of the file, and you also have to make a call to png_set_sig_bytes_read()
with the number of bytes you read from the beginning. Libpng will
then only check the bytes (if any) that your program didn't read.
(*): If you are not using the standard I/O functions, you will need
to replace them with custom functions. See the discussion under
Customizing libpng.
FILE *fp = fopen(file_name, "rb");
if (!fp)
{
return (ERROR);
}
fread(header, 1, number, fp);
is_png = !png_sig_cmp(header, 0, number);
if (!is_png)
{
return (NOT_PNG);
}
Next, png_struct and png_info need to be allocated and initialized. In
order to ensure that the size of these structures is correct even with a
dynamically linked libpng, there are functions to initialize and
allocate the structures. We also pass the library version, optional
pointers to error handling functions, and a pointer to a data struct for
use by the error functions, if necessary (the pointer and functions can
be NULL if the default error handlers are to be used). See the section
on Changes to Libpng below regarding the old initialization functions.
The structure allocation functions quietly return NULL if they fail to
create the structure, so your application should check for that.
png_structp png_ptr = png_create_read_struct
(PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
user_error_fn, user_warning_fn);
if (!png_ptr)
return (ERROR);
png_infop info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
{
png_destroy_read_struct(&png_ptr,
(png_infopp)NULL, (png_infopp)NULL);
return (ERROR);
}
If you want to use your own memory allocation routines,
use a libpng that was built with PNG_USER_MEM_SUPPORTED defined, and use
png_create_read_struct_2() instead of png_create_read_struct():
png_structp png_ptr = png_create_read_struct_2
(PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
user_error_fn, user_warning_fn, (png_voidp)
user_mem_ptr, user_malloc_fn, user_free_fn);
The error handling routines passed to png_create_read_struct()
and the memory alloc/free routines passed to png_create_struct_2()
are only necessary if you are not using the libpng supplied error
handling and memory alloc/free functions.
When libpng encounters an error, it expects to longjmp back
to your routine. Therefore, you will need to call setjmp and pass
your png_jmpbuf(png_ptr). If you read the file from different
routines, you will need to update the longjmp buffer every time you enter
a new routine that will call a png_*() function.
See your documentation of setjmp/longjmp for your compiler for more
information on setjmp/longjmp. See the discussion on libpng error
handling in the Customizing Libpng section below for more information
on the libpng error handling. If an error occurs, and libpng longjmp's
back to your setjmp, you will want to call png_destroy_read_struct() to
free any memory.
if (setjmp(png_jmpbuf(png_ptr)))
{
png_destroy_read_struct(&png_ptr, &info_ptr,
&end_info);
fclose(fp);
return (ERROR);
}
Pass (png_infopp)NULL instead of &end_info if you didn't create
an end_info structure.
If you would rather avoid the complexity of setjmp/longjmp issues,
you can compile libpng with PNG_NO_SETJMP, in which case
errors will result in a call to PNG_ABORT() which defaults to abort().
You can #define PNG_ABORT() to a function that does something
more useful than abort(), as long as your function does not
return.
Now you need to set up the input code. The default for libpng is to
use the C function fread(). If you use this, you will need to pass a
valid FILE * in the function png_init_io(). Be sure that the file is
opened in binary mode. If you wish to handle reading data in another
way, you need not call the png_init_io() function, but you must then
implement the libpng I/O methods discussed in the Customizing Libpng
section below.
png_init_io(png_ptr, fp);
If you had previously opened the file and read any of the signature from
the beginning in order to see if this was a PNG file, you need to let
libpng know that there are some bytes missing from the start of the file.
png_set_sig_bytes(png_ptr, number);
You can change the zlib compression buffer size to be used while
reading compressed data with
png_set_compression_buffer_size(png_ptr, buffer_size);
where the default size is 8192 bytes. Note that the buffer size
is changed immediately and the buffer is reallocated immediately,
instead of setting a flag to be acted upon later.
If you want CRC errors to be handled in a different manner than
the default, use
png_set_crc_action(png_ptr, crit_action, ancil_action);
The values for png_set_crc_action() say how libpng is to handle CRC errors in
ancillary and critical chunks, and whether to use the data contained
therein. Note that it is impossible to "discard" data in a critical
chunk.
Choices for (int) crit_action are
PNG_CRC_DEFAULT 0 error/quit
PNG_CRC_ERROR_QUIT 1 error/quit
PNG_CRC_WARN_USE 3 warn/use data
PNG_CRC_QUIET_USE 4 quiet/use data
PNG_CRC_NO_CHANGE 5 use the current value
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
PNG_CRC_WARN_DISCARD 2 warn/discard data
PNG_CRC_WARN_USE 3 warn/use data
PNG_CRC_QUIET_USE 4 quiet/use data
PNG_CRC_NO_CHANGE 5 use the current value
Setting up callback code
You can set up a callback function to handle any unknown chunks in the
input stream. You must supply the function
read_chunk_callback(png_structp png_ptr,
png_unknown_chunkp chunk);
{
/* The unknown chunk structure contains your
chunk data, along with similar data for any other
unknown chunks: */
png_byte name[5];
png_byte *data;
png_size_t size;
/* Note that libpng has already taken care of
the CRC handling */
/* put your code here. Search for your chunk in the
unknown chunk structure, process it, and return one
of the following: */
return (-n); /* chunk had an error */
return (0); /* did not recognize */
return (n); /* success */
}
(You can give your function another name that you like instead of
"read_chunk_callback")
To inform libpng about your function, use
png_set_read_user_chunk_fn(png_ptr, user_chunk_ptr,
read_chunk_callback);
This names not only the callback function, but also a user pointer that
you can retrieve with
png_get_user_chunk_ptr(png_ptr);
If you call the png_set_read_user_chunk_fn() function, then all unknown
chunks which the callback does not handle will be saved when read. You can
cause them to be discarded by returning '1' ("handled") instead of '0'. This
behavior will change in libpng 1.7 and the default handling set by the
png_set_keep_unknown_chunks() function, described below, will be used when the
callback returns 0. If you want the existing behavior you should set the global
default to PNG_HANDLE_CHUNK_IF_SAFE now; this is compatible with all current
versions of libpng and with 1.7. Libpng 1.6 issues a warning if you keep the
default, or PNG_HANDLE_CHUNK_NEVER, and the callback returns 0.
At this point, you can set up a callback function that will be
called after each row has been read, which you can use to control
a progress meter or the like. It's demonstrated in pngtest.c.
You must supply a function
void read_row_callback(png_structp png_ptr,
png_uint_32 row, int pass);
{
/* put your code here */
}
(You can give it another name that you like instead of "read_row_callback")
To inform libpng about your function, use
png_set_read_status_fn(png_ptr, read_row_callback);
When this function is called the row has already been completely processed and
the 'row' and 'pass' refer to the next row to be handled. For the
non-interlaced case the row that was just handled is simply one less than the
passed in row number, and pass will always be 0. For the interlaced case the
same applies unless the row value is 0, in which case the row just handled was
the last one from one of the preceding passes. Because interlacing may skip a
pass you cannot be sure that the preceding pass is just 'pass-1', if you really
need to know what the last pass is record (row,pass) from the callback and use
the last recorded value each time.
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
Unknown-chunk handling
Now you get to set the way the library processes unknown chunks in the
input PNG stream. Both known and unknown chunks will be read. Normal
behavior is that known chunks will be parsed into information in
various info_ptr members while unknown chunks will be discarded. This
behavior can be wasteful if your application will never use some known
chunk types. To change this, you can call:
png_set_keep_unknown_chunks(png_ptr, keep,
chunk_list, num_chunks);
keep - 0: default unknown chunk handling
1: ignore; do not keep
2: keep only if safe-to-copy
3: keep even if unsafe-to-copy
You can use these definitions:
PNG_HANDLE_CHUNK_AS_DEFAULT 0
PNG_HANDLE_CHUNK_NEVER 1
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
num_chunks - number of chunks affected; if 0, all
unknown chunks are affected. If positive,
only the chunks in the list are affected,
and if negative all unknown chunks and
all known chunks except for the IHDR,
PLTE, tRNS, IDAT, and IEND chunks are
affected.
Unknown chunks declared in this way will be saved as raw data onto a
list of png_unknown_chunk structures. If a chunk that is normally
known to libpng is named in the list, it will be handled as unknown,
according to the "keep" directive. If a chunk is named in successive
instances of png_set_keep_unknown_chunks(), the final instance will
take precedence. The IHDR and IEND chunks should not be named in
chunk_list; if they are, libpng will process them normally anyway.
If you know that your application will never make use of some particular
chunks, use PNG_HANDLE_CHUNK_NEVER (or 1) as demonstrated below.
Here is an example of the usage of png_set_keep_unknown_chunks(),
where the private "vpAg" chunk will later be processed by a user chunk
callback function:
png_byte vpAg[5]={118, 112, 65, 103, (png_byte) '\0'};
#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
png_byte unused_chunks[]=
{
104, 73, 83, 84, (png_byte) '\0', /* hIST */
105, 84, 88, 116, (png_byte) '\0', /* iTXt */
112, 67, 65, 76, (png_byte) '\0', /* pCAL */
115, 67, 65, 76, (png_byte) '\0', /* sCAL */
115, 80, 76, 84, (png_byte) '\0', /* sPLT */
116, 73, 77, 69, (png_byte) '\0', /* tIME */
};
#endif
...
#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
/* ignore all unknown chunks
* (use global setting "2" for libpng16 and earlier):
*/
png_set_keep_unknown_chunks(read_ptr, 2, NULL, 0);
/* except for vpAg: */
png_set_keep_unknown_chunks(read_ptr, 2, vpAg, 1);
/* also ignore unused known chunks: */
png_set_keep_unknown_chunks(read_ptr, 1, unused_chunks,
(int)(sizeof unused_chunks)/5);
#endif
User limits
The PNG specification allows the width and height of an image to be as
large as 2^31-1 (0x7fffffff), or about 2.147 billion rows and columns.
Larger images will be rejected immediately with a png_error() call. If
you wish to reduce these limits, you can use
png_set_user_limits(png_ptr, width_max, height_max);
to set your own limits (libpng may reject some very wide images
anyway because of potential buffer overflow conditions).
You should put this statement after you create the PNG structure and
before calling png_read_info(), png_read_png(), or png_process_data().
When writing a PNG datastream, put this statement before calling
png_write_info() or png_write_png().
If you need to retrieve the limits that are being applied, use
width_max = png_get_user_width_max(png_ptr);
height_max = png_get_user_height_max(png_ptr);
The PNG specification sets no limit on the number of ancillary chunks
allowed in a PNG datastream. You can impose a limit on the total number
of sPLT, tEXt, iTXt, zTXt, and unknown chunks that will be stored, with
png_set_chunk_cache_max(png_ptr, user_chunk_cache_max);
where 0x7fffffffL means unlimited. You can retrieve this limit with
chunk_cache_max = png_get_chunk_cache_max(png_ptr);
You can also set a limit on the amount of memory that a compressed chunk
other than IDAT can occupy, with
png_set_chunk_malloc_max(png_ptr, user_chunk_malloc_max);
and you can retrieve the limit with
chunk_malloc_max = png_get_chunk_malloc_max(png_ptr);
Any chunks that would cause either of these limits to be exceeded will
be ignored.
Information about your system
If you intend to display the PNG or to incorporate it in other image data you
need to tell libpng information about your display or drawing surface so that
libpng can convert the values in the image to match the display.
From libpng-1.5.4 this information can be set before reading the PNG file
header. In earlier versions png_set_gamma() existed but behaved incorrectly if
called before the PNG file header had been read and png_set_alpha_mode() did not
exist.
If you need to support versions prior to libpng-1.5.4 test the version number
as illustrated below using "PNG_LIBPNG_VER >= 10504" and follow the procedures
described in the appropriate manual page.
You give libpng the encoding expected by your system expressed as a 'gamma'
value. You can also specify a default encoding for the PNG file in
case the required information is missing from the file. By default libpng
assumes that the PNG data matches your system, to keep this default call:
png_set_gamma(png_ptr, screen_gamma, output_gamma);
or you can use the fixed point equivalent:
png_set_gamma_fixed(png_ptr, PNG_FP_1*screen_gamma,
PNG_FP_1*output_gamma);
If you don't know the gamma for your system it is probably 2.2 - a good
approximation to the IEC standard for display systems (sRGB). If images are
too contrasty or washed out you got the value wrong - check your system
documentation!
Many systems permit the system gamma to be changed via a lookup table in the
display driver, a few systems, including older Macs, change the response by
default. As of 1.5.4 three special values are available to handle common
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
to preserve overall accuracy.
The output_gamma value expresses how to decode the output values, not how
they are encoded. The values used correspond to the normal numbers used to
describe the overall gamma of a computer display system; for example 2.2 for
an sRGB conformant system. The values are scaled by 100000 in the _fixed
version of the API (so 220000 for sRGB.)
The inverse of the value is always used to provide a default for the PNG file
encoding if it has no gAMA chunk and if png_set_gamma() has not been called
to override the PNG gamma information.
When the ALPHA_OPTIMIZED mode is selected the output gamma is used to encode
opaque pixels however pixels with lower alpha values are not encoded,
regardless of the output gamma setting.
When the standard Porter Duff handling is requested with mode 1 the output
encoding is set to be linear and the output_gamma value is only relevant
as a default for input data that has no gamma information. The linear output
encoding will be overridden if png_set_gamma() is called - the results may be
highly unexpected!
The following numbers are derived from the sRGB standard and the research
behind it. sRGB is defined to be approximated by a PNG gAMA chunk value of
0.45455 (1/2.2) for PNG. The value implicitly includes any viewing
correction required to take account of any differences in the color
environment of the original scene and the intended display environment; the
value expresses how to *decode* the image for display, not how the original
data was *encoded*.
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
The Mac value is deduced from the sRGB based on an assumption that the actual
extra viewing correction used in early Mac display systems was implemented as
a power 1.45 lookup table.
Any system where a programmable lookup table is used or where the behavior of
the final display device characteristics can be changed requires system
specific code to obtain the current characteristic. However this can be
difficult and most PNG gamma correction only requires an approximate value.
By default, if png_set_alpha_mode() is not called, libpng assumes that all
values are unencoded, linear, values and that the output device also has a
linear characteristic. This is only very rarely correct - it is invariably
better to call png_set_alpha_mode() with PNG_DEFAULT_sRGB than rely on the
default if you don't know what the right answer is!
The special value PNG_GAMMA_MAC_18 indicates an older Mac system (pre Mac OS
10.6) which used a correction table to implement a somewhat lower gamma on an
otherwise sRGB system.
Both these values are reserved (not simple gamma values) in order to allow
more precise correction internally in the future.
NOTE: the values can be passed to either the fixed or floating
point APIs, but the floating point API will also accept floating point
values.
The second thing you may need to tell libpng about is how your system handles
alpha channel information. Some, but not all, PNG files contain an alpha
channel. To display these files correctly you need to compose the data onto a
suitable background, as described in the PNG specification.
Libpng only supports composing onto a single color (using png_set_background;
see below). Otherwise you must do the composition yourself and, in this case,
you may need to call png_set_alpha_mode:
#if PNG_LIBPNG_VER >= 10504
png_set_alpha_mode(png_ptr, mode, screen_gamma);
#else
png_set_gamma(png_ptr, screen_gamma, 1.0/screen_gamma);
#endif
The screen_gamma value is the same as the argument to png_set_gamma; however,
how it affects the output depends on the mode. png_set_alpha_mode() sets the
file gamma default to 1/screen_gamma, so normally you don't need to call
png_set_gamma. If you need different defaults call png_set_gamma() before
png_set_alpha_mode() - if you call it after it will override the settings made
by png_set_alpha_mode().
The mode is as follows:
PNG_ALPHA_PNG: The data is encoded according to the PNG
specification. Red, green and blue, or gray, components are
gamma encoded color values and are not premultiplied by the
alpha value. The alpha value is a linear measure of the
contribution of the pixel to the corresponding final output pixel.
You should normally use this format if you intend to perform
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
storing color channel values that have been scaled by the alpha. The
advantage is that the color channels can be resampled (the image can be
scaled) in this form. The disadvantage is that normal practice is to store
linear, not (gamma) encoded, values and this requires 16-bit channels for
still images rather than the 8-bit channels that are just about sufficient if
gamma encoding is used. In addition all non-transparent pixel values,
including completely opaque ones, must be gamma encoded to produce the final
image. These are the 'STANDARD', 'ASSOCIATED' or 'PREMULTIPLIED' modes
described below (the latter being the two common names for associated alpha
color channels). Note that PNG files always contain non-associated color
channels; png_set_alpha_mode() with one of the modes causes the decoder to
convert the pixels to an associated form before returning them to your
application.
Since it is not necessary to perform arithmetic on opaque color values so
long as they are not to be resampled and are in the final color space it is
possible to optimize the handling of alpha by storing the opaque pixels in
the PNG format (adjusted for the output color space) while storing partially
opaque pixels in the standard, linear, format. The accuracy required for
standard alpha composition is relatively low, because the pixels are
isolated, therefore typically the accuracy loss in storing 8-bit linear
values is acceptable. (This is not true if the alpha channel is used to
simulate transparency over large areas - use 16 bits or the PNG mode in
this case!) This is the 'OPTIMIZED' mode. For this mode a pixel is
treated as opaque only if the alpha value is equal to the maximum value.
PNG_ALPHA_STANDARD: The data libpng produces is encoded in the
standard way assumed by most correctly written graphics software.
The gamma encoding will be removed by libpng and the
linear component values will be pre-multiplied by the
alpha channel.
With this format the final image must be re-encoded to
match the display gamma before the image is displayed.
If your system doesn't do that, yet still seems to
perform arithmetic on the pixels without decoding them,
it is broken - check out the modes below.
With PNG_ALPHA_STANDARD libpng always produces linear
component values, whatever screen_gamma you supply. The
screen_gamma value is, however, used as a default for
the file gamma if the PNG file has no gamma information.
If you call png_set_gamma() after png_set_alpha_mode() you
will override the linear encoding. Instead the
pre-multiplied pixel values will be gamma encoded but
the alpha channel will still be linear. This may
actually match the requirements of some broken software,
but it is unlikely.
While linear 8-bit data is often used it has
insufficient precision for any image with a reasonable
dynamic range. To avoid problems, and if your software
supports it, use png_set_expand_16() to force all
components to 16 bits.
PNG_ALPHA_OPTIMIZED: This mode is the same as PNG_ALPHA_STANDARD
except that completely opaque pixels are gamma encoded according to
the screen_gamma value. Pixels with alpha less than 1.0
will still have linear components.
Use this format if you have control over your
compositing software and so don't do other arithmetic
(such as scaling) on the data you get from libpng. Your
compositing software can simply copy opaque pixels to
the output but still has linear values for the
non-opaque pixels.
In normal compositing, where the alpha channel encodes
partial pixel coverage (as opposed to broad area
translucency), the inaccuracies of the 8-bit
representation of non-opaque pixels are irrelevant.
You can also try this format if your software is broken;
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
broken because, in practice, no implementation that uses this choice
correctly undoes the encoding before handling alpha composition. Use this
choice only if other serious errors in the software or hardware you use
mandate it. In most cases of broken software or hardware the bug in the
final display manifests as a subtle halo around composited parts of the
image. You may not even perceive this as a halo; the composited part of
the image may simply appear separate from the background, as though it had
been cut out of paper and pasted on afterward.
If you don't have to deal with bugs in software or hardware, or if you can fix
them, there are three recommended ways of using png_set_alpha_mode():
png_set_alpha_mode(png_ptr, PNG_ALPHA_PNG,
screen_gamma);
You can do color correction on the result (libpng does not currently
support color correction internally). When you handle the alpha channel
you need to undo the gamma encoding and multiply out the alpha.
png_set_alpha_mode(png_ptr, PNG_ALPHA_STANDARD,
screen_gamma);
png_set_expand_16(png_ptr);
If you are using the high level interface, don't call png_set_expand_16();
instead pass PNG_TRANSFORM_EXPAND_16 to the interface.
With this mode you can't do color correction, but you can do arithmetic,
including composition and scaling, on the data without further processing.
png_set_alpha_mode(png_ptr, PNG_ALPHA_OPTIMIZED,
screen_gamma);
You can avoid the expansion to 16-bit components with this mode, but you
lose the ability to scale the image or perform other linear arithmetic.
All you can do is compose the result onto a matching output. Since this
mode is libpng-specific you also need to write your own composition
software.
The following are examples of calls to png_set_alpha_mode to achieve the
required overall gamma correction and, where necessary, alpha
premultiplication.
png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
This is the default libpng handling of the alpha channel - it is not
pre-multiplied into the color components. In addition the call states
that the output is for a sRGB system and causes all PNG files without gAMA
chunks to be assumed to be encoded using sRGB.
png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
In this case the output is assumed to be something like an sRGB conformant
display preceeded by a power-law lookup table of power 1.45. This is how
early Mac systems behaved.
png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_GAMMA_LINEAR);
This is the classic Jim Blinn approach and will work in academic
environments where everything is done by the book. It has the shortcoming
of assuming that input PNG data with no gamma information is linear - this
is unlikely to be correct unless the PNG files where generated locally.
Most of the time the output precision will be so low as to show
significant banding in dark areas of the image.
png_set_expand_16(pp);
png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_DEFAULT_sRGB);
This is a somewhat more realistic Jim Blinn inspired approach. PNG files
are assumed to have the sRGB encoding if not marked with a gamma value and
the output is always 16 bits per component. This permits accurate scaling
and processing of the data. If you know that your input PNG files were
generated locally you might need to replace PNG_DEFAULT_sRGB with the
correct value for your system.
png_set_alpha_mode(pp, PNG_ALPHA_OPTIMIZED, PNG_DEFAULT_sRGB);
If you just need to composite the PNG image onto an existing background
and if you control the code that does this you can use the optimization
setting. In this case you just copy completely opaque pixels to the
output. For pixels that are not completely transparent (you just skip
those) you do the composition math using png_composite or png_composite_16
below then encode the resultant 8-bit or 16-bit values to match the output
encoding.
Other cases
If neither the PNG nor the standard linear encoding work for you because
of the software or hardware you use then you have a big problem. The PNG
case will probably result in halos around the image. The linear encoding
will probably result in a washed out, too bright, image (it's actually too
contrasty.) Try the ALPHA_OPTIMIZED mode above - this will probably
substantially reduce the halos. Alternatively try:
png_set_alpha_mode(pp, PNG_ALPHA_BROKEN, PNG_DEFAULT_sRGB);
This option will also reduce the halos, but there will be slight dark
halos round the opaque parts of the image where the background is light.
In the OPTIMIZED mode the halos will be light halos where the background
is dark. Take your pick - the halos are unavoidable unless you can get
your hardware/software fixed! (The OPTIMIZED approach is slightly
faster.)
When the default gamma of PNG files doesn't match the output gamma.
If you have PNG files with no gamma information png_set_alpha_mode allows
you to provide a default gamma, but it also sets the ouput gamma to the
matching value. If you know your PNG files have a gamma that doesn't
match the output you can take advantage of the fact that
png_set_alpha_mode always sets the output gamma but only sets the PNG
default if it is not already set:
png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
The first call sets both the default and the output gamma values, the
second call overrides the output gamma without changing the default. This
is easier than achieving the same effect with png_set_gamma. You must use
PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will
fire if more than one call to png_set_alpha_mode and png_set_background is
made in the same read operation, however multiple calls with PNG_ALPHA_PNG
are ignored.
If you don't need, or can't handle, the alpha channel you can call
png_set_background() to remove it by compositing against a fixed color. Don't
call png_set_strip_alpha() to do this - it will leave spurious pixel values in
transparent parts of this image.
png_set_background(png_ptr, &background_color,
PNG_BACKGROUND_GAMMA_SCREEN, 0, 1);
The background_color is an RGB or grayscale value according to the data format
libpng will produce for you. Because you don't yet know the format of the PNG
file, if you call png_set_background at this point you must arrange for the
format produced by libpng to always have 8-bit or 16-bit components and then
store the color as an 8-bit or 16-bit color as appropriate. The color contains
separate gray and RGB component values, so you can let libpng produce gray or
RGB output according to the input format, but low bit depth grayscale images
must always be converted to at least 8-bit format. (Even though low bit depth
grayscale images can't have an alpha channel they can have a transparent
color!)
You set the transforms you need later, either as flags to the high level
interface or libpng API calls for the low level interface. For reference the
settings and API calls required are:
8-bit values:
PNG_TRANSFORM_SCALE_16 | PNG_EXPAND
png_set_expand(png_ptr); png_set_scale_16(png_ptr);
If you must get exactly the same inaccurate results
produced by default in versions prior to libpng-1.5.4,
use PNG_TRANSFORM_STRIP_16 and png_set_strip_16(png_ptr)
instead.
16-bit values:
PNG_TRANSFORM_EXPAND_16
png_set_expand_16(png_ptr);
In either case palette image data will be expanded to RGB. If you just want
color data you can add PNG_TRANSFORM_GRAY_TO_RGB or png_set_gray_to_rgb(png_ptr)
to the list.
Calling png_set_background before the PNG file header is read will not work
prior to libpng-1.5.4. Because the failure may result in unexpected warnings or
errors it is therefore much safer to call png_set_background after the head has
been read. Unfortunately this means that prior to libpng-1.5.4 it cannot be
used with the high level interface.
The high-level read interface
At this point there are two ways to proceed; through the high-level
read interface, or through a sequence of low-level read operations.
You can use the high-level interface if (a) you are willing to read
the entire image into memory, and (b) the input transformations
you want to do are limited to the following set:
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
to transparency
PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
PNG_TRANSFORM_GRAY_TO_RGB Expand grayscale samples
to RGB (or GA to RGBA)
PNG_TRANSFORM_EXPAND_16 Expand samples to 16 bits
(This excludes setting a background color, doing gamma transformation,
quantizing, and setting filler.) If this is the case, simply do this:
png_read_png(png_ptr, info_ptr, png_transforms, NULL)
where png_transforms is an integer containing the bitwise OR of some
set of transformation flags. This call is equivalent to png_read_info(),
followed the set of transformations indicated by the transform mask,
then png_read_image(), and finally png_read_end().
(The final parameter of this call is not yet used. Someday it might point
to transformation parameters required by some future input transform.)
You must use png_transforms and not call any png_set_transform() functions
when you use png_read_png().
After you have called png_read_png(), you can retrieve the image data
with
row_pointers = png_get_rows(png_ptr, info_ptr);
where row_pointers is an array of pointers to the pixel data for each row:
png_bytep row_pointers[height];
If you know your image size and pixel size ahead of time, you can allocate
row_pointers prior to calling png_read_png() with
if (height > PNG_UINT_32_MAX/(sizeof (png_byte)))
png_error (png_ptr,
"Image is too tall to process in memory");
if (width > PNG_UINT_32_MAX/pixel_size)
png_error (png_ptr,
"Image is too wide to process in memory");
row_pointers = png_malloc(png_ptr,
height*(sizeof (png_bytep)));
for (int i=0; i<height, i++)
row_pointers[i]=NULL; /* security precaution */
for (int i=0; i<height, i++)
row_pointers[i]=png_malloc(png_ptr,
width*pixel_size);
png_set_rows(png_ptr, info_ptr, &row_pointers);
Alternatively you could allocate your image in one big block and define
row_pointers[i] to point into the proper places in your block.
If you use png_set_rows(), the application is responsible for freeing
row_pointers (and row_pointers[i], if they were separately allocated).
If you don't allocate row_pointers ahead of time, png_read_png() will
do it, and it'll be free'ed by libpng when you call png_destroy_*().
The low-level read interface
If you are going the low-level route, you are now ready to read all
the file information up to the actual image data. You do this with a
call to png_read_info().
png_read_info(png_ptr, info_ptr);
This will process all chunks up to but not including the image data.
This also copies some of the data from the PNG file into the decode structure
for use in later transformations. Important information copied in is:
1) The PNG file gamma from the gAMA chunk. This overwrites the default value
provided by an earlier call to png_set_gamma or png_set_alpha_mode.
2) Prior to libpng-1.5.4 the background color from a bKGd chunk. This
damages the information provided by an earlier call to png_set_background
resulting in unexpected behavior. Libpng-1.5.4 no longer does this.
3) The number of significant bits in each component value. Libpng uses this to
optimize gamma handling by reducing the internal lookup table sizes.
4) The transparent color information from a tRNS chunk. This can be modified by
a later call to png_set_tRNS.
Querying the info structure
Functions are used to get the information from the info_ptr once it
has been read. Note that these fields may not be completely filled
in until png_read_end() has read the chunk data following the image.
png_get_IHDR(png_ptr, info_ptr, &width, &height,
&bit_depth, &color_type, &interlace_type,
&compression_type, &filter_method);
width - holds the width of the image
in pixels (up to 2^31).
height - holds the height of the image
in pixels (up to 2^31).
bit_depth - holds the bit depth of one of the
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
filter_method - (must be PNG_FILTER_TYPE_BASE
for PNG 1.0, and can also be
PNG_INTRAPIXEL_DIFFERENCING if
the PNG datastream is embedded in
a MNG-1.0 datastream)
Any or all of interlace_type, compression_type, or
filter_method can be NULL if you are
not interested in their values.
Note that png_get_IHDR() returns 32-bit data into
the application's width and height variables.
This is an unsafe situation if these are 16-bit
variables. In such situations, the
png_get_image_width() and png_get_image_height()
functions described below are safer.
width = png_get_image_width(png_ptr,
info_ptr);
height = png_get_image_height(png_ptr,
info_ptr);
bit_depth = png_get_bit_depth(png_ptr,
info_ptr);
color_type = png_get_color_type(png_ptr,
info_ptr);
interlace_type = png_get_interlace_type(png_ptr,
info_ptr);
compression_type = png_get_compression_type(png_ptr,
info_ptr);
filter_method = png_get_filter_type(png_ptr,
info_ptr);
channels = png_get_channels(png_ptr, info_ptr);
channels - number of channels of info for the
color type (valid values are 1 (GRAY,
PALETTE), 2 (GRAY_ALPHA), 3 (RGB),
4 (RGB_ALPHA or RGB + filler byte))
rowbytes = png_get_rowbytes(png_ptr, info_ptr);
rowbytes - number of bytes needed to hold a row
signature = png_get_signature(png_ptr, info_ptr);
signature - holds the signature read from the
file (if any). The data is kept in
the same offset it would be if the
whole signature were read (i.e. if an
application had already read in 4
bytes of signature before starting
libpng, the remaining 4 bytes would
be in signature[4] through signature[7]
(see png_set_sig_bytes())).
These are also important, but their validity depends on whether the chunk
has been read. The png_get_valid(png_ptr, info_ptr, PNG_INFO_<chunk>) and
png_get_<chunk>(png_ptr, info_ptr, ...) functions return non-zero if the
data has been read, or zero if it is missing. The parameters to the
png_get_<chunk> are set directly if they are simple data types, or a
pointer into the info_ptr is returned for any complex types.
The colorspace data from gAMA, cHRM, sRGB, iCCP, and sBIT chunks
is simply returned to give the application information about how the
image was encoded. Libpng itself only does transformations using the file
gamma when combining semitransparent pixels with the background color, and,
since libpng-1.6.0, when converting between 8-bit sRGB and 16-bit linear pixels
within the simplified API. Libpng also uses the file gamma when converting
RGB to gray, beginning with libpng-1.0.5, if the application calls
png_set_rgb_to_gray()).
png_get_PLTE(png_ptr, info_ptr, &palette,
&num_palette);
palette - the palette for the file
(array of png_color)
num_palette - number of entries in the palette
png_get_gAMA(png_ptr, info_ptr, &file_gamma);
png_get_gAMA_fixed(png_ptr, info_ptr, &int_file_gamma);
file_gamma - the gamma at which the file is
written (PNG_INFO_gAMA)
int_file_gamma - 100,000 times the gamma at which the
file is written
png_get_cHRM(png_ptr, info_ptr, &white_x, &white_y, &red_x,
&red_y, &green_x, &green_y, &blue_x, &blue_y)
png_get_cHRM_XYZ(png_ptr, info_ptr, &red_X, &red_Y, &red_Z,
&green_X, &green_Y, &green_Z, &blue_X, &blue_Y,
&blue_Z)
png_get_cHRM_fixed(png_ptr, info_ptr, &int_white_x,
&int_white_y, &int_red_x, &int_red_y,
&int_green_x, &int_green_y, &int_blue_x,
&int_blue_y)
png_get_cHRM_XYZ_fixed(png_ptr, info_ptr, &int_red_X, &int_red_Y,
&int_red_Z, &int_green_X, &int_green_Y,
&int_green_Z, &int_blue_X, &int_blue_Y,
&int_blue_Z)
{white,red,green,blue}_{x,y}
A color space encoding specified using the
chromaticities of the end points and the
white point. (PNG_INFO_cHRM)
{red,green,blue}_{X,Y,Z}
A color space encoding specified using the
encoding end points - the CIE tristimulus
specification of the intended color of the red,
green and blue channels in the PNG RGB data.
The white point is simply the sum of the three
end points. (PNG_INFO_cHRM)
png_get_sRGB(png_ptr, info_ptr, &srgb_intent);
srgb_intent - the rendering intent (PNG_INFO_sRGB)
The presence of the sRGB chunk
means that the pixel data is in the
sRGB color space. This chunk also
implies specific values of gAMA and
cHRM.
png_get_iCCP(png_ptr, info_ptr, &name,
&compression_type, &profile, &proflen);
name - The profile name.
compression_type - The compression type; always
PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
You may give NULL to this argument to
ignore it.
profile - International Color Consortium color
profile data. May contain NULs.
proflen - length of profile data in bytes.
png_get_sBIT(png_ptr, info_ptr, &sig_bit);
sig_bit - the number of significant bits for
(PNG_INFO_sBIT) each of the gray,
red, green, and blue channels,
whichever are appropriate for the
given color type (png_color_16)
png_get_tRNS(png_ptr, info_ptr, &trans_alpha,
&num_trans, &trans_color);
trans_alpha - array of alpha (transparency)
entries for palette (PNG_INFO_tRNS)
num_trans - number of transparent entries
(PNG_INFO_tRNS)
trans_color - graylevel or color sample values of
the single transparent color for
non-paletted images (PNG_INFO_tRNS)
png_get_hIST(png_ptr, info_ptr, &hist);
(PNG_INFO_hIST)
hist - histogram of palette (array of
png_uint_16)
png_get_tIME(png_ptr, info_ptr, &mod_time);
mod_time - time image was last modified
(PNG_VALID_tIME)
png_get_bKGD(png_ptr, info_ptr, &background);
background - background color (of type
png_color_16p) (PNG_VALID_bKGD)
valid 16-bit red, green and blue
values, regardless of color_type
num_comments = png_get_text(png_ptr, info_ptr,
&text_ptr, &num_text);
num_comments - number of comments
text_ptr - array of png_text holding image
comments
text_ptr[i].compression - type of compression used
on "text" PNG_TEXT_COMPRESSION_NONE
PNG_TEXT_COMPRESSION_zTXt
PNG_ITXT_COMPRESSION_NONE
PNG_ITXT_COMPRESSION_zTXt
text_ptr[i].key - keyword for comment. Must contain
1-79 characters.
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
text_ptr[i].lang - language of comment (empty
string for unknown).
text_ptr[i].lang_key - keyword in UTF-8
(empty string for unknown).
Note that the itxt_length, lang, and lang_key
members of the text_ptr structure only exist when the
library is built with iTXt chunk support. Prior to
libpng-1.4.0 the library was built by default without
iTXt support. Also note that when iTXt is supported,
they contain NULL pointers when the "compression"
field contains PNG_TEXT_COMPRESSION_NONE or
PNG_TEXT_COMPRESSION_zTXt.
num_text - number of comments (same as
num_comments; you can put NULL here
to avoid the duplication)
Note while png_set_text() will accept text, language,
and translated keywords that can be NULL pointers, the
structure returned by png_get_text will always contain
regular zero-terminated C strings. They might be
empty strings but they will never be NULL pointers.
num_spalettes = png_get_sPLT(png_ptr, info_ptr,
&palette_ptr);
num_spalettes - number of sPLT chunks read.
palette_ptr - array of palette structures holding
contents of one or more sPLT chunks
read.
png_get_oFFs(png_ptr, info_ptr, &offset_x, &offset_y,
&unit_type);
offset_x - positive offset from the left edge
of the screen (can be negative)
offset_y - positive offset from the top edge
of the screen (can be negative)
unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
png_get_pHYs(png_ptr, info_ptr, &res_x, &res_y,
&unit_type);
res_x - pixels/unit physical resolution in
x direction
res_y - pixels/unit physical resolution in
x direction
unit_type - PNG_RESOLUTION_UNKNOWN,
PNG_RESOLUTION_METER
png_get_sCAL(png_ptr, info_ptr, &unit, &width,
&height)
unit - physical scale units (an integer)
width - width of a pixel in physical scale units
height - height of a pixel in physical scale units
(width and height are doubles)
png_get_sCAL_s(png_ptr, info_ptr, &unit, &width,
&height)
unit - physical scale units (an integer)
width - width of a pixel in physical scale units
(expressed as a string)
height - height of a pixel in physical scale units
(width and height are strings like "2.54")
num_unknown_chunks = png_get_unknown_chunks(png_ptr,
info_ptr, &unknowns)
unknowns - array of png_unknown_chunk
structures holding unknown chunks
unknowns[i].name - name of unknown chunk
unknowns[i].data - data of unknown chunk
unknowns[i].size - size of unknown chunk's data
unknowns[i].location - position of chunk in file
The value of "i" corresponds to the order in which the
chunks were read from the PNG file or inserted with the
png_set_unknown_chunks() function.
The value of "location" is a bitwise "or" of
PNG_HAVE_IHDR (0x01)
PNG_HAVE_PLTE (0x02)
PNG_AFTER_IDAT (0x08)
The data from the pHYs chunk can be retrieved in several convenient
forms:
res_x = png_get_x_pixels_per_meter(png_ptr,
info_ptr)
res_y = png_get_y_pixels_per_meter(png_ptr,
info_ptr)
res_x_and_y = png_get_pixels_per_meter(png_ptr,
info_ptr)
res_x = png_get_x_pixels_per_inch(png_ptr,
info_ptr)
res_y = png_get_y_pixels_per_inch(png_ptr,
info_ptr)
res_x_and_y = png_get_pixels_per_inch(png_ptr,
info_ptr)
aspect_ratio = png_get_pixel_aspect_ratio(png_ptr,
info_ptr)
Each of these returns 0 [signifying "unknown"] if
the data is not present or if res_x is 0;
res_x_and_y is 0 if res_x != res_y
Note that because of the way the resolutions are
stored internally, the inch conversions won't
come out to exactly even number. For example,
72 dpi is stored as 0.28346 pixels/meter, and
when this is retrieved it is 71.9988 dpi, so
be sure to round the returned value appropriately
if you want to display a reasonable-looking result.
The data from the oFFs chunk can be retrieved in several convenient
forms:
x_offset = png_get_x_offset_microns(png_ptr, info_ptr);
y_offset = png_get_y_offset_microns(png_ptr, info_ptr);
x_offset = png_get_x_offset_inches(png_ptr, info_ptr);
y_offset = png_get_y_offset_inches(png_ptr, info_ptr);
Each of these returns 0 [signifying "unknown" if both
x and y are 0] if the data is not present or if the
chunk is present but the unit is the pixel. The
remark about inexact inch conversions applies here
as well, because a value in inches can't always be
converted to microns and back without some loss
of precision.
For more information, see the
PNG specification for chunk contents. Be careful with trusting
rowbytes, as some of the transformations could increase the space
needed to hold a row (expand, filler, gray_to_rgb, etc.).
See png_read_update_info(), below.
A quick word about text_ptr and num_text. PNG stores comments in
keyword/text pairs, one pair per chunk, with no limit on the number
of text chunks, and a 2^31 byte limit on their size. While there are
suggested keywords, there is no requirement to restrict the use to these
strings. It is strongly suggested that keywords and text be sensible
to humans (that's the point), so don't use abbreviations. Non-printing
symbols are not allowed. See the PNG specification for more details.
There is also no requirement to have text after the keyword.
Keywords should be limited to 79 Latin-1 characters without leading or
trailing spaces, but non-consecutive spaces are allowed within the
keyword. It is possible to have the same keyword any number of times.
The text_ptr is an array of png_text structures, each holding a
pointer to a language string, a pointer to a keyword and a pointer to
a text string. The text string, language code, and translated
keyword may be empty or NULL pointers. The keyword/text
pairs are put into the array in the order that they are received.
However, some or all of the text chunks may be after the image, so, to
make sure you have read all the text chunks, don't mess with these
until after you read the stuff after the image. This will be
mentioned again below in the discussion that goes with png_read_end().
Input transformations
After you've read the header information, you can set up the library
to handle any special transformations of the image data. The various
ways to transform the data will be described in the order that they
should occur. This is important, as some of these change the color
type and/or bit depth of the data, and some others only work on
certain color types and bit depths.
Transformations you request are ignored if they don't have any meaning for a
particular input data format. However some transformations can have an effect
as a result of a previous transformation. If you specify a contradictory set of
transformations, for example both adding and removing the alpha channel, you
cannot predict the final result.
The color used for the transparency values should be supplied in the same
format/depth as the current image data. It is stored in the same format/depth
as the image data in a tRNS chunk, so this is what libpng expects for this data.
The color used for the background value depends on the need_expand argument as
described below.
Data will be decoded into the supplied row buffers packed into bytes
unless the library has been told to transform it into another format.
For example, 4 bit/pixel paletted or grayscale data will be returned
2 pixels/byte with the leftmost pixel in the high-order bits of the
byte, unless png_set_packing() is called. 8-bit RGB data will be stored
in RGB RGB RGB format unless png_set_filler() or png_set_add_alpha()
is called to insert filler bytes, either before or after each RGB triplet.
16-bit RGB data will be returned RRGGBB RRGGBB, with the most significant
byte of the color value first, unless png_set_scale_16() is called to
transform it to regular RGB RGB triplets, or png_set_filler() or
png_set_add alpha() is called to insert filler bytes, either before or
after each RRGGBB triplet. Similarly, 8-bit or 16-bit grayscale data can
be modified with png_set_filler(), png_set_add_alpha(), png_set_strip_16(),
or png_set_scale_16().
The following code transforms grayscale images of less than 8 to 8 bits,
changes paletted images to RGB, and adds a full alpha channel if there is
transparency information in a tRNS chunk. This is most useful on
grayscale images with bit depths of 2 or 4 or if there is a multiple-image
viewing application that wishes to treat all images in the same way.
if (color_type == PNG_COLOR_TYPE_PALETTE)
png_set_palette_to_rgb(png_ptr);
if (png_get_valid(png_ptr, info_ptr,
PNG_INFO_tRNS)) png_set_tRNS_to_alpha(png_ptr);
if (color_type == PNG_COLOR_TYPE_GRAY &&
bit_depth < 8) png_set_expand_gray_1_2_4_to_8(png_ptr);
The first two functions are actually aliases for png_set_expand(), added
in libpng version 1.0.4, with the function names expanded to improve code
readability. In some future version they may actually do different
things.
As of libpng version 1.2.9, png_set_expand_gray_1_2_4_to_8() was
added. It expands the sample depth without changing tRNS to alpha.
As of libpng version 1.5.2, png_set_expand_16() was added. It behaves as
png_set_expand(); however, the resultant channels have 16 bits rather than 8.
Use this when the output color or gray channels are made linear to avoid fairly
severe accuracy loss.
if (bit_depth < 16)
png_set_expand_16(png_ptr);
PNG can have files with 16 bits per channel. If you only can handle
8 bits per channel, this will strip the pixels down to 8-bit.
if (bit_depth == 16)
#if PNG_LIBPNG_VER >= 10504
png_set_scale_16(png_ptr);
#else
png_set_strip_16(png_ptr);
#endif
(The more accurate "png_set_scale_16()" API became available in libpng version
1.5.4).
If you need to process the alpha channel on the image separately from the image
data (for example if you convert it to a bitmap mask) it is possible to have
libpng strip the channel leaving just RGB or gray data:
if (color_type & PNG_COLOR_MASK_ALPHA)
png_set_strip_alpha(png_ptr);
If you strip the alpha channel you need to find some other way of dealing with
the information. If, instead, you want to convert the image to an opaque
version with no alpha channel use png_set_background; see below.
As of libpng version 1.5.2, almost all useful expansions are supported, the
major ommissions are conversion of grayscale to indexed images (which can be
done trivially in the application) and conversion of indexed to grayscale (which
can be done by a trivial manipulation of the palette.)
In the following table, the 01 means grayscale with depth<8, 31 means
indexed with depth<8, other numerals represent the color type, "T" means
the tRNS chunk is present, A means an alpha channel is present, and O
means tRNS or alpha is present but all pixels in the image are opaque.
FROM 01 31 0 0T 0O 2 2T 2O 3 3T 3O 4A 4O 6A 6O
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
3O [Qt] p [Qt][Q] [Q] Qt Qt Qt t t + [Qt][Qt] Qt Qt
4A lA G A T T GA GT GT GA GT GT + BA G GBA
4O lA GBA A T T GA GT GT GA GT GT BA + GBA G
6A CA PA CA C C A T tT PA P P C CBA + BA
6O CA PBA CA C C A tT T PA P P CBA C BA +
Within the matrix,
"+" identifies entries where 'from' and 'to' are the same.
"-" means the transformation is not supported.
"." means nothing is necessary (a tRNS chunk can just be ignored).
"t" means the transformation is obtained by png_set_tRNS.
"A" means the transformation is obtained by png_set_add_alpha().
"X" means the transformation is obtained by png_set_expand().
"1" means the transformation is obtained by
png_set_expand_gray_1_2_4_to_8() (and by png_set_expand()
if there is no transparency in the original or the final
format).
"C" means the transformation is obtained by png_set_gray_to_rgb().
"G" means the transformation is obtained by png_set_rgb_to_gray().
"P" means the transformation is obtained by
png_set_expand_palette_to_rgb().
"p" means the transformation is obtained by png_set_packing().
"Q" means the transformation is obtained by png_set_quantize().
"T" means the transformation is obtained by
png_set_tRNS_to_alpha().
"B" means the transformation is obtained by
png_set_background(), or png_strip_alpha().
When an entry has multiple transforms listed all are required to cause the
right overall transformation. When two transforms are separated by a comma
either will do the job. When transforms are enclosed in [] the transform should
do the job but this is currently unimplemented - a different format will result
if the suggested transformations are used.
In PNG files, the alpha channel in an image
is the level of opacity. If you need the alpha channel in an image to
be the level of transparency instead of opacity, you can invert the
alpha channel (or the tRNS chunk data) after it's read, so that 0 is
fully opaque and 255 (in 8-bit or paletted images) or 65535 (in 16-bit
images) is fully transparent, with
png_set_invert_alpha(png_ptr);
PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
they can, resulting in, for example, 8 pixels per byte for 1 bit
files. This code expands to 1 pixel per byte without changing the
values of the pixels:
if (bit_depth < 8)
png_set_packing(png_ptr);
PNG files have possible bit depths of 1, 2, 4, 8, and 16. All pixels
stored in a PNG image have been "scaled" or "shifted" up to the next
higher possible bit depth (e.g. from 5 bits/sample in the range [0,31]
to 8 bits/sample in the range [0, 255]). However, it is also possible
to convert the PNG pixel data back to the original bit depth of the
image. This call reduces the pixels back down to the original bit depth:
png_color_8p sig_bit;
if (png_get_sBIT(png_ptr, info_ptr, &sig_bit))
png_set_shift(png_ptr, sig_bit);
PNG files store 3-color pixels in red, green, blue order. This code
changes the storage of the pixels to blue, green, red:
if (color_type == PNG_COLOR_TYPE_RGB ||
color_type == PNG_COLOR_TYPE_RGB_ALPHA)
png_set_bgr(png_ptr);
PNG files store RGB pixels packed into 3 or 6 bytes. This code expands them
into 4 or 8 bytes for windowing systems that need them in this format:
if (color_type == PNG_COLOR_TYPE_RGB)
png_set_filler(png_ptr, filler, PNG_FILLER_BEFORE);
where "filler" is the 8 or 16-bit number to fill with, and the location is
either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether
you want the filler before the RGB or after. This transformation
does not affect images that already have full alpha channels. To add an
opaque alpha channel, use filler=0xff or 0xffff and PNG_FILLER_AFTER which
will generate RGBA pixels.
Note that png_set_filler() does not change the color type. If you want
to do that, you can add a true alpha channel with
if (color_type == PNG_COLOR_TYPE_RGB ||
color_type == PNG_COLOR_TYPE_GRAY)
png_set_add_alpha(png_ptr, filler, PNG_FILLER_AFTER);
where "filler" contains the alpha value to assign to each pixel.
This function was added in libpng-1.2.7.
If you are reading an image with an alpha channel, and you need the
data as ARGB instead of the normal PNG format RGBA:
if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
png_set_swap_alpha(png_ptr);
For some uses, you may want a grayscale image to be represented as
RGB. This code will do that conversion:
if (color_type == PNG_COLOR_TYPE_GRAY ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
png_set_gray_to_rgb(png_ptr);
Conversely, you can convert an RGB or RGBA image to grayscale or grayscale
with alpha.
if (color_type == PNG_COLOR_TYPE_RGB ||
color_type == PNG_COLOR_TYPE_RGB_ALPHA)
png_set_rgb_to_gray(png_ptr, error_action,
double red_weight, double green_weight);
error_action = 1: silently do the conversion
error_action = 2: issue a warning if the original
image has any pixel where
red != green or red != blue
error_action = 3: issue an error and abort the
conversion if the original
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
red_weight: weight of red component
green_weight: weight of green component
If either weight is negative, default
weights are used.
In the corresponding fixed point API the red_weight and green_weight values are
simply scaled by 100,000:
png_set_rgb_to_gray(png_ptr, error_action,
png_fixed_point red_weight,
png_fixed_point green_weight);
If you have set error_action = 1 or 2, you can
later check whether the image really was gray, after processing
the image rows, with the png_get_rgb_to_gray_status(png_ptr) function.
It will return a png_byte that is zero if the image was gray or
1 if there were any non-gray pixels. Background and sBIT data
will be silently converted to grayscale, using the green channel
data for sBIT, regardless of the error_action setting.
The default values come from the PNG file cHRM chunk if present; otherwise, the
defaults correspond to the ITU-R recommendation 709, and also the sRGB color
space, as recommended in the Charles Poynton's Colour FAQ,
<http://www.poynton.com/>, in section 9:
<http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html#RTFToC9>
Y = 0.2126 * R + 0.7152 * G + 0.0722 * B
Previous versions of this document, 1998 through 2002, recommended a slightly
different formula:
Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
Libpng uses an integer approximation:
Y = (6968 * R + 23434 * G + 2366 * B)/32768
The calculation is done in a linear colorspace, if the image gamma
can be determined.
The png_set_background() function has been described already; it tells libpng to
composite images with alpha or simple transparency against the supplied
background color. For compatibility with versions of libpng earlier than
libpng-1.5.4 it is recommended that you call the function after reading the file
header, even if you don't want to use the color in a bKGD chunk, if one exists.
If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid),
you may use this color, or supply another color more suitable for
the current display (e.g., the background color from a web page). You
need to tell libpng how the color is represented, both the format of the
component values in the color (the number of bits) and the gamma encoding of the
color. The function takes two arguments, background_gamma_mode and need_expand
to convey this information; however, only two combinations are likely to be
useful:
png_color_16 my_background;
png_color_16p image_background;
if (png_get_bKGD(png_ptr, info_ptr, &image_background))
png_set_background(png_ptr, image_background,
PNG_BACKGROUND_GAMMA_FILE, 1/*needs to be expanded*/, 1);
else
png_set_background(png_ptr, &my_background,
PNG_BACKGROUND_GAMMA_SCREEN, 0/*do not expand*/, 1);
The second call was described above - my_background is in the format of the
final, display, output produced by libpng. Because you now know the format of
the PNG it is possible to avoid the need to choose either 8-bit or 16-bit
output and to retain palette images (the palette colors will be modified
appropriately and the tRNS chunk removed.) However, if you are doing this,
take great care not to ask for transformations without checking first that
they apply!
In the first call the background color has the original bit depth and color type
of the PNG file. So, for palette images the color is supplied as a palette
index and for low bit greyscale images the color is a reduced bit value in
image_background->gray.
If you didn't call png_set_gamma() before reading the file header, for example
if you need your code to remain compatible with older versions of libpng prior
to libpng-1.5.4, this is the place to call it.
Do not call it if you called png_set_alpha_mode(); doing so will damage the
settings put in place by png_set_alpha_mode(). (If png_set_alpha_mode() is
supported then you can certainly do png_set_gamma() before reading the PNG
header.)
This API unconditionally sets the screen and file gamma values, so it will
override the value in the PNG file unless it is called before the PNG file
reading starts. For this reason you must always call it with the PNG file
value when you call it in this position:
if (png_get_gAMA(png_ptr, info_ptr, &file_gamma))
png_set_gamma(png_ptr, screen_gamma, file_gamma);
else
png_set_gamma(png_ptr, screen_gamma, 0.45455);
If you need to reduce an RGB file to a paletted file, or if a paletted
file has more entries then will fit on your screen, png_set_quantize()
will do that. Note that this is a simple match quantization that merely
finds the closest color available. This should work fairly well with
optimized palettes, but fairly badly with linear color cubes. If you
pass a palette that is larger than maximum_colors, the file will
reduce the number of colors in the palette so it will fit into
maximum_colors. If there is a histogram, libpng will use it to make
more intelligent choices when reducing the palette. If there is no
histogram, it may not do as good a job.
if (color_type & PNG_COLOR_MASK_COLOR)
{
if (png_get_valid(png_ptr, info_ptr,
PNG_INFO_PLTE))
{
png_uint_16p histogram = NULL;
png_get_hIST(png_ptr, info_ptr,
&histogram);
png_set_quantize(png_ptr, palette, num_palette,
max_screen_colors, histogram, 1);
}
else
{
png_color std_color_cube[MAX_SCREEN_COLORS] =
{ ... colors ... };
png_set_quantize(png_ptr, std_color_cube,
MAX_SCREEN_COLORS, MAX_SCREEN_COLORS,
NULL,0);
}
}
PNG files describe monochrome as black being zero and white being one.
The following code will reverse this (make black be one and white be
zero):
if (bit_depth == 1 && color_type == PNG_COLOR_TYPE_GRAY)
png_set_invert_mono(png_ptr);
This function can also be used to invert grayscale and gray-alpha images:
if (color_type == PNG_COLOR_TYPE_GRAY ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
png_set_invert_mono(png_ptr);
PNG files store 16-bit pixels in network byte order (big-endian,
ie. most significant bits first). This code changes the storage to the
other way (little-endian, i.e. least significant bits first, the
way PCs store them):
if (bit_depth == 16)
png_set_swap(png_ptr);
If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
need to change the order the pixels are packed into bytes, you can use:
if (bit_depth < 8)
png_set_packswap(png_ptr);
Finally, you can write your own transformation function if none of
the existing ones meets your needs. This is done by setting a callback
with
png_set_read_user_transform_fn(png_ptr,
read_transform_fn);
You must supply the function
void read_transform_fn(png_structp png_ptr, png_row_infop
row_info, png_bytep data)
See pngtest.c for a working example. Your function will be called
after all of the other transformations have been processed. Take care with
interlaced images if you do the interlace yourself - the width of the row is the
width in 'row_info', not the overall image width.
If supported, libpng provides two information routines that you can use to find
where you are in processing the image:
png_get_current_pass_number(png_structp png_ptr);
png_get_current_row_number(png_structp png_ptr);
Don't try using these outside a transform callback - firstly they are only
supported if user transforms are supported, secondly they may well return
unexpected results unless the row is actually being processed at the moment they
are called.
With interlaced
images the value returned is the row in the input sub-image image. Use
PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass).
The discussion of interlace handling above contains more information on how to
use these values.
You can also set up a pointer to a user structure for use by your
callback function, and you can inform libpng that your transform
function will change the number of channels or bit depth with the
function
png_set_user_transform_info(png_ptr, user_ptr,
user_depth, user_channels);
The user's application, not libpng, is responsible for allocating and
freeing any memory required for the user structure.
You can retrieve the pointer via the function
png_get_user_transform_ptr(). For example:
voidp read_user_transform_ptr =
png_get_user_transform_ptr(png_ptr);
The last thing to handle is interlacing; this is covered in detail below,
but you must call the function here if you want libpng to handle expansion
of the interlaced image.
number_of_passes = png_set_interlace_handling(png_ptr);
After setting the transformations, libpng can update your png_info
structure to reflect any transformations you've requested with this
call.
png_read_update_info(png_ptr, info_ptr);
This is most useful to update the info structure's rowbytes
field so you can use it to allocate your image memory. This function
will also update your palette with the correct screen_gamma and
background if these have been given with the calls above. You may
only call png_read_update_info() once with a particular info_ptr.
After you call png_read_update_info(), you can allocate any
memory you need to hold the image. The row data is simply
raw byte data for all forms of images. As the actual allocation
varies among applications, no example will be given. If you
are allocating one large chunk, you will need to build an
array of pointers to each row, as it will be needed for some
of the functions below.
Remember: Before you call png_read_update_info(), the png_get_*()
functions return the values corresponding to the original PNG image.
After you call png_read_update_info the values refer to the image
that libpng will output. Consequently you must call all the png_set_
functions before you call png_read_update_info(). This is particularly
important for png_set_interlace_handling() - if you are going to call
png_read_update_info() you must call png_set_interlace_handling() before
it unless you want to receive interlaced output.
Reading image data
After you've allocated memory, you can read the image data.
The simplest way to do this is in one function call. If you are
allocating enough memory to hold the whole image, you can just
call png_read_image() and libpng will read in all the image data
and put it in the memory area supplied. You will need to pass in
an array of pointers to each row.
This function automatically handles interlacing, so you don't
need to call png_set_interlace_handling() (unless you call
png_read_update_info()) or call this function multiple times, or any
of that other stuff necessary with png_read_rows().
png_read_image(png_ptr, row_pointers);
where row_pointers is:
png_bytep row_pointers[height];
You can point to void or char or whatever you use for pixels.
If you don't want to read in the whole image at once, you can
use png_read_rows() instead. If there is no interlacing (check
interlace_type == PNG_INTERLACE_NONE), this is simple:
png_read_rows(png_ptr, row_pointers, NULL,
number_of_rows);
where row_pointers is the same as in the png_read_image() call.
If you are doing this just one row at a time, you can do this with
a single row_pointer instead of an array of row_pointers:
png_bytep row_pointer = row;
png_read_row(png_ptr, row_pointer, NULL);
If the file is interlaced (interlace_type != 0 in the IHDR chunk), things
get somewhat harder. The only current (PNG Specification version 1.2)
interlacing type for PNG is (interlace_type == PNG_INTERLACE_ADAM7);
a somewhat complicated 2D interlace scheme, known as Adam7, that
breaks down an image into seven smaller images of varying size, based
on an 8x8 grid. This number is defined (from libpng 1.5) as
PNG_INTERLACE_ADAM7_PASSES in png.h
libpng can fill out those images or it can give them to you "as is".
It is almost always better to have libpng handle the interlacing for you.
If you want the images filled out, there are two ways to do that. The one
mentioned in the PNG specification is to expand each pixel to cover
those pixels that have not been read yet (the "rectangle" method).
This results in a blocky image for the first pass, which gradually
smooths out as more pixels are read. The other method is the "sparkle"
method, where pixels are drawn only in their final locations, with the
rest of the image remaining whatever colors they were initialized to
before the start of the read. The first method usually looks better,
but tends to be slower, as there are more pixels to put in the rows.
If, as is likely, you want libpng to expand the images, call this before
calling png_start_read_image() or png_read_update_info():
if (interlace_type == PNG_INTERLACE_ADAM7)
number_of_passes
= png_set_interlace_handling(png_ptr);
This will return the number of passes needed. Currently, this is seven,
but may change if another interlace type is added. This function can be
called even if the file is not interlaced, where it will return one pass.
You then need to read the whole image 'number_of_passes' times. Each time
will distribute the pixels from the current pass to the correct place in
the output image, so you need to supply the same rows to png_read_rows in
each pass.
If you are not going to display the image after each pass, but are
going to wait until the entire image is read in, use the sparkle
effect. This effect is faster and the end result of either method
is exactly the same. If you are planning on displaying the image
after each pass, the "rectangle" effect is generally considered the
better looking one.
If you only want the "sparkle" effect, just call png_read_rows() as
normal, with the third parameter NULL. Make sure you make pass over
the image number_of_passes times, and you don't change the data in the
rows between calls. You can change the locations of the data, just
not the data. Each pass only writes the pixels appropriate for that
pass, and assumes the data from previous passes is still valid.
png_read_rows(png_ptr, row_pointers, NULL,
number_of_rows);
If you only want the first effect (the rectangles), do the same as
before except pass the row buffer in the third parameter, and leave
the second parameter NULL.
png_read_rows(png_ptr, NULL, row_pointers,
number_of_rows);
If you don't want libpng to handle the interlacing details, just call
png_read_rows() PNG_INTERLACE_ADAM7_PASSES times to read in all the images.
Each of the images is a valid image by itself; however, you will almost
certainly need to distribute the pixels from each sub-image to the
correct place. This is where everything gets very tricky.
If you want to retrieve the separate images you must pass the correct
number of rows to each successive call of png_read_rows(). The calculation
gets pretty complicated for small images, where some sub-images may
not even exist because either their width or height ends up zero.
libpng provides two macros to help you in 1.5 and later versions:
png_uint_32 width = PNG_PASS_COLS(image_width, pass_number);
png_uint_32 height = PNG_PASS_ROWS(image_height, pass_number);
Respectively these tell you the width and height of the sub-image
corresponding to the numbered pass. 'pass' is in in the range 0 to 6 -
this can be confusing because the specification refers to the same passes
as 1 to 7! Be careful, you must check both the width and height before
calling png_read_rows() and not call it for that pass if either is zero.
You can, of course, read each sub-image row by row. If you want to
produce optimal code to make a pixel-by-pixel transformation of an
interlaced image this is the best approach; read each row of each pass,
transform it, and write it out to a new interlaced image.
If you want to de-interlace the image yourself libpng provides further
macros to help that tell you where to place the pixels in the output image.
Because the interlacing scheme is rectangular - sub-image pixels are always
arranged on a rectangular grid - all you need to know for each pass is the
starting column and row in the output image of the first pixel plus the
spacing between each pixel. As of libpng 1.5 there are four macros to
retrieve this information:
png_uint_32 x = PNG_PASS_START_COL(pass);
png_uint_32 y = PNG_PASS_START_ROW(pass);
png_uint_32 xStep = 1U << PNG_PASS_COL_SHIFT(pass);
png_uint_32 yStep = 1U << PNG_PASS_ROW_SHIFT(pass);
These allow you to write the obvious loop:
png_uint_32 input_y = 0;
png_uint_32 output_y = PNG_PASS_START_ROW(pass);
while (output_y < output_image_height)
{
png_uint_32 input_x = 0;
png_uint_32 output_x = PNG_PASS_START_COL(pass);
while (output_x < output_image_width)
{
image[output_y][output_x] =
subimage[pass][input_y][input_x++];
output_x += xStep;
}
++input_y;
output_y += yStep;
}
Notice that the steps between successive output rows and columns are
returned as shifts. This is possible because the pixels in the subimages
are always a power of 2 apart - 1, 2, 4 or 8 pixels - in the original
image. In practice you may need to directly calculate the output coordinate
given an input coordinate. libpng provides two further macros for this
purpose:
png_uint_32 output_x = PNG_COL_FROM_PASS_COL(input_x, pass);
png_uint_32 output_y = PNG_ROW_FROM_PASS_ROW(input_y, pass);
Finally a pair of macros are provided to tell you if a particular image
row or column appears in a given pass:
int col_in_pass = PNG_COL_IN_INTERLACE_PASS(output_x, pass);
int row_in_pass = PNG_ROW_IN_INTERLACE_PASS(output_y, pass);
Bear in mind that you will probably also need to check the width and height
of the pass in addition to the above to be sure the pass even exists!
With any luck you are convinced by now that you don't want to do your own
interlace handling. In reality normally the only good reason for doing this
is if you are processing PNG files on a pixel-by-pixel basis and don't want
to load the whole file into memory when it is interlaced.
libpng includes a test program, pngvalid, that illustrates reading and
writing of interlaced images. If you can't get interlacing to work in your
code and don't want to leave it to libpng (the recommended approach), see
how pngvalid.c does it.
Finishing a sequential read
After you are finished reading the image through the
low-level interface, you can finish reading the file.
If you want to use a different crc action for handling CRC errors in
chunks after the image data, you can call png_set_crc_action()
again at this point.
If you are interested in comments or time, which may be stored either
before or after the image data, you should pass the separate png_info
struct if you want to keep the comments from before and after the image
separate.
png_infop end_info = png_create_info_struct(png_ptr);
if (!end_info)
{
png_destroy_read_struct(&png_ptr, &info_ptr,
(png_infopp)NULL);
return (ERROR);
}
png_read_end(png_ptr, end_info);
If you are not interested, you should still call png_read_end()
but you can pass NULL, avoiding the need to create an end_info structure.
If you do this, libpng will not process any chunks after IDAT other than
skipping over them and perhaps (depending on whether you have called
png_set_crc_action) checking their CRCs while looking for the IEND chunk.
png_read_end(png_ptr, (png_infop)NULL);
If you don't call png_read_end(), then your file pointer will be
left pointing to the first chunk after the last IDAT, which is probably
not what you want if you expect to read something beyond the end of
the PNG datastream.
When you are done, you can free all memory allocated by libpng like this:
png_destroy_read_struct(&png_ptr, &info_ptr,
&end_info);
or, if you didn't create an end_info structure,
png_destroy_read_struct(&png_ptr, &info_ptr,
(png_infopp)NULL);
It is also possible to individually free the info_ptr members that
point to libpng-allocated storage with the following function:
png_free_data(png_ptr, info_ptr, mask, seq)
mask - identifies data to be freed, a mask
containing the bitwise OR of one or
more of
PNG_FREE_PLTE, PNG_FREE_TRNS,
PNG_FREE_HIST, PNG_FREE_ICCP,
PNG_FREE_PCAL, PNG_FREE_ROWS,
PNG_FREE_SCAL, PNG_FREE_SPLT,
PNG_FREE_TEXT, PNG_FREE_UNKN,
or simply PNG_FREE_ALL
seq - sequence number of item to be freed
(-1 for all items)
This function may be safely called when the relevant storage has
already been freed, or has not yet been allocated, or was allocated
by the user and not by libpng, and will in those cases do nothing.
The "seq" parameter is ignored if only one item of the selected data
type, such as PLTE, is allowed. If "seq" is not -1, and multiple items
are allowed for the data type identified in the mask, such as text or
sPLT, only the n'th item in the structure is freed, where n is "seq".
The default behavior is only to free data that was allocated internally
by libpng. This can be changed, so that libpng will not free the data,
or so that it will free data that was allocated by the user with png_malloc()
or png_calloc() and passed in via a png_set_*() function, with
png_data_freer(png_ptr, info_ptr, freer, mask)
freer - one of
PNG_DESTROY_WILL_FREE_DATA
PNG_SET_WILL_FREE_DATA
PNG_USER_WILL_FREE_DATA
mask - which data elements are affected
same choices as in png_free_data()
This function only affects data that has already been allocated.
You can call this function after reading the PNG data but before calling
any png_set_*() functions, to control whether the user or the png_set_*()
function is responsible for freeing any existing data that might be present,
and again after the png_set_*() functions to control whether the user
or png_destroy_*() is supposed to free the data. When the user assumes
responsibility for libpng-allocated data, the application must use
png_free() to free it, and when the user transfers responsibility to libpng
for data that the user has allocated, the user must have used png_malloc()
or png_calloc() to allocate it.
If you allocated your row_pointers in a single block, as suggested above in
the description of the high level read interface, you must not transfer
responsibility for freeing it to the png_set_rows or png_read_destroy function,
because they would also try to free the individual row_pointers[i].
If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
separately, do not transfer responsibility for freeing text_ptr to libpng,
because when libpng fills a png_text structure it combines these members with
the key member, and png_free_data() will free only text_ptr.key. Similarly,
if you transfer responsibility for free'ing text_ptr from libpng to your
application, your application must not separately free those members.
The png_free_data() function will turn off the "valid" flag for anything
it frees. If you need to turn the flag off for a chunk that was freed by
your application instead of by libpng, you can use
png_set_invalid(png_ptr, info_ptr, mask);
mask - identifies the chunks to be made invalid,
containing the bitwise OR of one or
more of
PNG_INFO_gAMA, PNG_INFO_sBIT,
PNG_INFO_cHRM, PNG_INFO_PLTE,
PNG_INFO_tRNS, PNG_INFO_bKGD,
PNG_INFO_hIST, PNG_INFO_pHYs,
PNG_INFO_oFFs, PNG_INFO_tIME,
PNG_INFO_pCAL, PNG_INFO_sRGB,
PNG_INFO_iCCP, PNG_INFO_sPLT,
PNG_INFO_sCAL, PNG_INFO_IDAT
For a more compact example of reading a PNG image, see the file example.c.
Reading PNG files progressively
The progressive reader is slightly different from the non-progressive
reader. Instead of calling png_read_info(), png_read_rows(), and
png_read_end(), you make one call to png_process_data(), which calls
callbacks when it has the info, a row, or the end of the image. You
set up these callbacks with png_set_progressive_read_fn(). You don't
have to worry about the input/output functions of libpng, as you are
giving the library the data directly in png_process_data(). I will
assume that you have read the section on reading PNG files above,
so I will only highlight the differences (although I will show
all of the code).
png_structp png_ptr;
png_infop info_ptr;
/* An example code fragment of how you would
initialize the progressive reader in your
application. */
int
initialize_png_reader()
{
png_ptr = png_create_read_struct
(PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
user_error_fn, user_warning_fn);
if (!png_ptr)
return (ERROR);
info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
{
png_destroy_read_struct(&png_ptr,
(png_infopp)NULL, (png_infopp)NULL);
return (ERROR);
}
if (setjmp(png_jmpbuf(png_ptr)))
{
png_destroy_read_struct(&png_ptr, &info_ptr,
(png_infopp)NULL);
return (ERROR);
}
/* This one's new. You can provide functions
to be called when the header info is valid,
when each row is completed, and when the image
is finished. If you aren't using all functions,
you can specify NULL parameters. Even when all
three functions are NULL, you need to call
png_set_progressive_read_fn(). You can use
any struct as the user_ptr (cast to a void pointer
for the function call), and retrieve the pointer
from inside the callbacks using the function
png_get_progressive_ptr(png_ptr);
which will return a void pointer, which you have
to cast appropriately.
*/
png_set_progressive_read_fn(png_ptr, (void *)user_ptr,
info_callback, row_callback, end_callback);
return 0;
}
/* A code fragment that you call as you receive blocks
of data */
int
process_data(png_bytep buffer, png_uint_32 length)
{
if (setjmp(png_jmpbuf(png_ptr)))
{
png_destroy_read_struct(&png_ptr, &info_ptr,
(png_infopp)NULL);
return (ERROR);
}
/* This one's new also. Simply give it a chunk
of data from the file stream (in order, of
course). On machines with segmented memory
models machines, don't give it any more than
64K. The library seems to run fine with sizes
of 4K. Although you can give it much less if
necessary (I assume you can give it chunks of
1 byte, I haven't tried less then 256 bytes
yet). When this function returns, you may
want to display any rows that were generated
in the row callback if you don't already do
so there.
*/
png_process_data(png_ptr, info_ptr, buffer, length);
/* At this point you can call png_process_data_skip if
you want to handle data the library will skip yourself;
it simply returns the number of bytes to skip (and stops
libpng skipping that number of bytes on the next
png_process_data call).
return 0;
}
/* This function is called (as set by
png_set_progressive_read_fn() above) when enough data
has been supplied so all of the header has been
read.
*/
void
info_callback(png_structp png_ptr, png_infop info)
{
/* Do any setup here, including setting any of
the transformations mentioned in the Reading
PNG files section. For now, you _must_ call
either png_start_read_image() or
png_read_update_info() after all the
transformations are set (even if you don't set
any). You may start getting rows before
png_process_data() returns, so this is your
last chance to prepare for that.
This is where you turn on interlace handling,
assuming you don't want to do it yourself.
If you need to you can stop the processing of
your original input data at this point by calling
png_process_data_pause. This returns the number
of unprocessed bytes from the last png_process_data
call - it is up to you to ensure that the next call
sees these bytes again. If you don't want to bother
with this you can get libpng to cache the unread
bytes by setting the 'save' parameter (see png.h) but
then libpng will have to copy the data internally.
*/
}
/* This function is called when each row of image
data is complete */
void
row_callback(png_structp png_ptr, png_bytep new_row,
png_uint_32 row_num, int pass)
{
/* If the image is interlaced, and you turned
on the interlace handler, this function will
be called for every row in every pass. Some
of these rows will not be changed from the
previous pass. When the row is not changed,
the new_row variable will be NULL. The rows
and passes are called in order, so you don't
really need the row_num and pass, but I'm
supplying them because it may make your life
easier.
If you did not turn on interlace handling then
the callback is called for each row of each
sub-image when the image is interlaced. In this
case 'row_num' is the row in the sub-image, not
the row in the output image as it is in all other
cases.
For the non-NULL rows of interlaced images when
you have switched on libpng interlace handling,
you must call png_progressive_combine_row()
passing in the row and the old row. You can
call this function for NULL rows (it will just
return) and for non-interlaced images (it just
does the memcpy for you) if it will make the
code easier. Thus, you can just do this for
all cases if you switch on interlace handling;
*/
png_progressive_combine_row(png_ptr, old_row,
new_row);
/* where old_row is what was displayed
previously for the row. Note that the first
pass (pass == 0, really) will completely cover
the old row, so the rows do not have to be
initialized. After the first pass (and only
for interlaced images), you will have to pass
the current row, and the function will combine
the old row and the new row.
You can also call png_process_data_pause in this
callback - see above.
*/
}
void
end_callback(png_structp png_ptr, png_infop info)
{
/* This function is called after the whole image
has been read, including any chunks after the
image (up to and including the IEND). You
will usually have the same info chunk as you
had in the header, although some data may have
been added to the comments and time fields.
Most people won't do much here, perhaps setting
a flag that marks the image as finished.
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
IV. Writing
Much of this is very similar to reading. However, everything of
importance is repeated here, so you won't have to constantly look
back up in the reading section to understand writing.
Setup
You will want to do the I/O initialization before you get into libpng,
so if it doesn't work, you don't have anything to undo. If you are not
using the standard I/O functions, you will need to replace them with
custom writing functions. See the discussion under Customizing libpng.
FILE *fp = fopen(file_name, "wb");
if (!fp)
return (ERROR);
Next, png_struct and png_info need to be allocated and initialized.
As these can be both relatively large, you may not want to store these
on the stack, unless you have stack space to spare. Of course, you
will want to check if they return NULL. If you are also reading,
you won't want to name your read structure and your write structure
both "png_ptr"; you can call them anything you like, such as
"read_ptr" and "write_ptr". Look at pngtest.c, for example.
png_structp png_ptr = png_create_write_struct
(PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
user_error_fn, user_warning_fn);
if (!png_ptr)
return (ERROR);
png_infop info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
{
png_destroy_write_struct(&png_ptr,
(png_infopp)NULL);
return (ERROR);
}
If you want to use your own memory allocation routines,
define PNG_USER_MEM_SUPPORTED and use
png_create_write_struct_2() instead of png_create_write_struct():
png_structp png_ptr = png_create_write_struct_2
(PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
user_error_fn, user_warning_fn, (png_voidp)
user_mem_ptr, user_malloc_fn, user_free_fn);
After you have these structures, you will need to set up the
error handling. When libpng encounters an error, it expects to
longjmp() back to your routine. Therefore, you will need to call
setjmp() and pass the png_jmpbuf(png_ptr). If you
write the file from different routines, you will need to update
the png_jmpbuf(png_ptr) every time you enter a new routine that will
call a png_*() function. See your documentation of setjmp/longjmp
for your compiler for more information on setjmp/longjmp. See
the discussion on libpng error handling in the Customizing Libpng
section below for more information on the libpng error handling.
if (setjmp(png_jmpbuf(png_ptr)))
{
png_destroy_write_struct(&png_ptr, &info_ptr);
fclose(fp);
return (ERROR);
}
...
return;
If you would rather avoid the complexity of setjmp/longjmp issues,
you can compile libpng with PNG_NO_SETJMP, in which case
errors will result in a call to PNG_ABORT() which defaults to abort().
You can #define PNG_ABORT() to a function that does something
more useful than abort(), as long as your function does not
return.
Checking for invalid palette index on write was added at libpng
1.5.10. If a pixel contains an invalid (out-of-range) index libpng issues
a benign error. This is enabled by default because this condition is an
error according to the PNG specification, Clause 11.3.2, but the error can
be ignored in each png_ptr with
png_set_check_for_invalid_index(png_ptr, 0);
If the error is ignored, or if png_benign_error() treats it as a warning,
any invalid pixels are written as-is by the encoder, resulting in an
invalid PNG datastream as output. In this case the application is
responsible for ensuring that the pixel indexes are in range when it writes
a PLTE chunk with fewer entries than the bit depth would allow.
Now you need to set up the output code. The default for libpng is to
use the C function fwrite(). If you use this, you will need to pass a
valid FILE * in the function png_init_io(). Be sure that the file is
opened in binary mode. Again, if you wish to handle writing data in
another way, see the discussion on libpng I/O handling in the Customizing
Libpng section below.
png_init_io(png_ptr, fp);
If you are embedding your PNG into a datastream such as MNG, and don't
want libpng to write the 8-byte signature, or if you have already
written the signature in your application, use
png_set_sig_bytes(png_ptr, 8);
to inform libpng that it should not write a signature.
Write callbacks
At this point, you can set up a callback function that will be
called after each row has been written, which you can use to control
a progress meter or the like. It's demonstrated in pngtest.c.
You must supply a function
void write_row_callback(png_structp png_ptr, png_uint_32 row,
int pass);
{
/* put your code here */
}
(You can give it another name that you like instead of "write_row_callback")
To inform libpng about your function, use
png_set_write_status_fn(png_ptr, write_row_callback);
When this function is called the row has already been completely processed and
it has also been written out. The 'row' and 'pass' refer to the next row to be
handled. For the
non-interlaced case the row that was just handled is simply one less than the
passed in row number, and pass will always be 0. For the interlaced case the
same applies unless the row value is 0, in which case the row just handled was
the last one from one of the preceding passes. Because interlacing may skip a
pass you cannot be sure that the preceding pass is just 'pass-1', if you really
need to know what the last pass is record (row,pass) from the callback and use
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
As with the user transform you can find the output row using the
PNG_ROW_FROM_PASS_ROW macro.
You now have the option of modifying how the compression library will
run. The following functions are mainly for testing, but may be useful
in some cases, like if you need to write PNG files extremely fast and
are willing to give up some compression, or if you want to get the
maximum possible compression at the expense of slower writing. If you
have no special needs in this area, let the library do what it wants by
not calling this function at all, as it has been tuned to deliver a good
speed/compression ratio. The second parameter to png_set_filter() is
the filter method, for which the only valid values are 0 (as of the
July 1999 PNG specification, version 1.2) or 64 (if you are writing
a PNG datastream that is to be embedded in a MNG datastream). The third
parameter is a flag that indicates which filter type(s) are to be tested
for each scanline. See the PNG specification for details on the specific
filter types.
/* turn on or off filtering, and/or choose
specific filters. You can use either a single
PNG_FILTER_VALUE_NAME or the bitwise OR of one
or more PNG_FILTER_NAME masks.
*/
png_set_filter(png_ptr, 0,
PNG_FILTER_NONE | PNG_FILTER_VALUE_NONE |
PNG_FILTER_SUB | PNG_FILTER_VALUE_SUB |
PNG_FILTER_UP | PNG_FILTER_VALUE_UP |
PNG_FILTER_AVG | PNG_FILTER_VALUE_AVG |
PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH|
PNG_ALL_FILTERS);
If an application wants to start and stop using particular filters during
compression, it should start out with all of the filters (to ensure that
the previous row of pixels will be stored in case it's needed later),
and then add and remove them after the start of compression.
If you are writing a PNG datastream that is to be embedded in a MNG
datastream, the second parameter can be either 0 or 64.
The png_set_compression_*() functions interface to the zlib compression
library, and should mostly be ignored unless you really know what you are
doing. The only generally useful call is png_set_compression_level()
which changes how much time zlib spends on trying to compress the image
data. See the Compression Library (zlib.h and algorithm.txt, distributed
with zlib) for details on the compression levels.
#include zlib.h
/* Set the zlib compression level */
png_set_compression_level(png_ptr,
Z_BEST_COMPRESSION);
/* Set other zlib parameters for compressing IDAT */
png_set_compression_mem_level(png_ptr, 8);
png_set_compression_strategy(png_ptr,
Z_DEFAULT_STRATEGY);
png_set_compression_window_bits(png_ptr, 15);
png_set_compression_method(png_ptr, 8);
png_set_compression_buffer_size(png_ptr, 8192)
/* Set zlib parameters for text compression
* If you don't call these, the parameters
* fall back on those defined for IDAT chunks
*/
png_set_text_compression_mem_level(png_ptr, 8);
png_set_text_compression_strategy(png_ptr,
Z_DEFAULT_STRATEGY);
png_set_text_compression_window_bits(png_ptr, 15);
png_set_text_compression_method(png_ptr, 8);
Setting the contents of info for output
You now need to fill in the png_info structure with all the data you
wish to write before the actual image. Note that the only thing you
are allowed to write after the image is the text chunks and the time
chunk (as of PNG Specification 1.2, anyway). See png_write_end() and
the latest PNG specification for more information on that. If you
wish to write them before the image, fill them in now, and flag that
data as being valid. If you want to wait until after the data, don't
fill them until png_write_end(). For all the fields in png_info and
their data types, see png.h. For explanations of what the fields
contain, see the PNG specification.
Some of the more important parts of the png_info are:
png_set_IHDR(png_ptr, info_ptr, width, height,
bit_depth, color_type, interlace_type,
compression_type, filter_method)
width - holds the width of the image
in pixels (up to 2^31).
height - holds the height of the image
in pixels (up to 2^31).
bit_depth - holds the bit depth of one of the
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
compression_type - (must be
PNG_COMPRESSION_TYPE_DEFAULT)
filter_method - (must be PNG_FILTER_TYPE_DEFAULT
or, if you are writing a PNG to
be embedded in a MNG datastream,
can also be
PNG_INTRAPIXEL_DIFFERENCING)
If you call png_set_IHDR(), the call must appear before any of the
other png_set_*() functions, because they might require access to some of
the IHDR settings. The remaining png_set_*() functions can be called
in any order.
If you wish, you can reset the compression_type, interlace_type, or
filter_method later by calling png_set_IHDR() again; if you do this, the
width, height, bit_depth, and color_type must be the same in each call.
png_set_PLTE(png_ptr, info_ptr, palette,
num_palette);
palette - the palette for the file
(array of png_color)
num_palette - number of entries in the palette
png_set_gAMA(png_ptr, info_ptr, file_gamma);
png_set_gAMA_fixed(png_ptr, info_ptr, int_file_gamma);
file_gamma - the gamma at which the image was
created (PNG_INFO_gAMA)
int_file_gamma - 100,000 times the gamma at which
the image was created
png_set_cHRM(png_ptr, info_ptr, white_x, white_y, red_x, red_y,
green_x, green_y, blue_x, blue_y)
png_set_cHRM_XYZ(png_ptr, info_ptr, red_X, red_Y, red_Z, green_X,
green_Y, green_Z, blue_X, blue_Y, blue_Z)
png_set_cHRM_fixed(png_ptr, info_ptr, int_white_x, int_white_y,
int_red_x, int_red_y, int_green_x, int_green_y,
int_blue_x, int_blue_y)
png_set_cHRM_XYZ_fixed(png_ptr, info_ptr, int_red_X, int_red_Y,
int_red_Z, int_green_X, int_green_Y, int_green_Z,
int_blue_X, int_blue_Y, int_blue_Z)
{white,red,green,blue}_{x,y}
A color space encoding specified using the chromaticities
of the end points and the white point.
{red,green,blue}_{X,Y,Z}
A color space encoding specified using the encoding end
points - the CIE tristimulus specification of the intended
color of the red, green and blue channels in the PNG RGB
data. The white point is simply the sum of the three end
points.
png_set_sRGB(png_ptr, info_ptr, srgb_intent);
srgb_intent - the rendering intent
(PNG_INFO_sRGB) The presence of
the sRGB chunk means that the pixel
data is in the sRGB color space.
This chunk also implies specific
values of gAMA and cHRM. Rendering
intent is the CSS-1 property that
has been defined by the International
Color Consortium
(http://www.color.org).
It can be one of
PNG_sRGB_INTENT_SATURATION,
PNG_sRGB_INTENT_PERCEPTUAL,
PNG_sRGB_INTENT_ABSOLUTE, or
PNG_sRGB_INTENT_RELATIVE.
png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr,
srgb_intent);
srgb_intent - the rendering intent
(PNG_INFO_sRGB) The presence of the
sRGB chunk means that the pixel
data is in the sRGB color space.
This function also causes gAMA and
cHRM chunks with the specific values
that are consistent with sRGB to be
written.
png_set_iCCP(png_ptr, info_ptr, name, compression_type,
profile, proflen);
name - The profile name.
compression_type - The compression type; always
PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
You may give NULL to this argument to
ignore it.
profile - International Color Consortium color
profile data. May contain NULs.
proflen - length of profile data in bytes.
png_set_sBIT(png_ptr, info_ptr, sig_bit);
sig_bit - the number of significant bits for
(PNG_INFO_sBIT) each of the gray, red,
green, and blue channels, whichever are
appropriate for the given color type
(png_color_16)
png_set_tRNS(png_ptr, info_ptr, trans_alpha,
num_trans, trans_color);
trans_alpha - array of alpha (transparency)
entries for palette (PNG_INFO_tRNS)
num_trans - number of transparent entries
(PNG_INFO_tRNS)
trans_color - graylevel or color sample values
(in order red, green, blue) of the
single transparent color for
non-paletted images (PNG_INFO_tRNS)
png_set_hIST(png_ptr, info_ptr, hist);
hist - histogram of palette (array of
png_uint_16) (PNG_INFO_hIST)
png_set_tIME(png_ptr, info_ptr, mod_time);
mod_time - time image was last modified
(PNG_VALID_tIME)
png_set_bKGD(png_ptr, info_ptr, background);
background - background color (of type
png_color_16p) (PNG_VALID_bKGD)
png_set_text(png_ptr, info_ptr, text_ptr, num_text);
text_ptr - array of png_text holding image
comments
text_ptr[i].compression - type of compression used
on "text" PNG_TEXT_COMPRESSION_NONE
PNG_TEXT_COMPRESSION_zTXt
PNG_ITXT_COMPRESSION_NONE
PNG_ITXT_COMPRESSION_zTXt
text_ptr[i].key - keyword for comment. Must contain
1-79 characters.
text_ptr[i].text - text comments for current
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
text_ptr[i].itxt_length - length of itxt string,
after decompression, 0 for tEXt/zTXt
text_ptr[i].lang - language of comment (NULL or
empty for unknown).
text_ptr[i].translated_keyword - keyword in UTF-8 (NULL
or empty for unknown).
Note that the itxt_length, lang, and lang_key
members of the text_ptr structure only exist when the
library is built with iTXt chunk support. Prior to
libpng-1.4.0 the library was built by default without
iTXt support. Also note that when iTXt is supported,
they contain NULL pointers when the "compression"
field contains PNG_TEXT_COMPRESSION_NONE or
PNG_TEXT_COMPRESSION_zTXt.
num_text - number of comments
png_set_sPLT(png_ptr, info_ptr, &palette_ptr,
num_spalettes);
palette_ptr - array of png_sPLT_struct structures
to be added to the list of palettes
in the info structure.
num_spalettes - number of palette structures to be
added.
png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y,
unit_type);
offset_x - positive offset from the left
edge of the screen
offset_y - positive offset from the top
edge of the screen
unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
png_set_pHYs(png_ptr, info_ptr, res_x, res_y,
unit_type);
res_x - pixels/unit physical resolution
in x direction
res_y - pixels/unit physical resolution
in y direction
unit_type - PNG_RESOLUTION_UNKNOWN,
PNG_RESOLUTION_METER
png_set_sCAL(png_ptr, info_ptr, unit, width, height)
unit - physical scale units (an integer)
width - width of a pixel in physical scale units
height - height of a pixel in physical scale units
(width and height are doubles)
png_set_sCAL_s(png_ptr, info_ptr, unit, width, height)
unit - physical scale units (an integer)
width - width of a pixel in physical scale units
expressed as a string
height - height of a pixel in physical scale units
(width and height are strings like "2.54")
png_set_unknown_chunks(png_ptr, info_ptr, &unknowns,
num_unknowns)
unknowns - array of png_unknown_chunk
structures holding unknown chunks
unknowns[i].name - name of unknown chunk
unknowns[i].data - data of unknown chunk
unknowns[i].size - size of unknown chunk's data
unknowns[i].location - position to write chunk in file
0: do not write chunk
PNG_HAVE_IHDR: before PLTE
PNG_HAVE_PLTE: before IDAT
PNG_AFTER_IDAT: after IDAT
The "location" member is set automatically according to
what part of the output file has already been written.
You can change its value after calling png_set_unknown_chunks()
as demonstrated in pngtest.c. Within each of the "locations",
the chunks are sequenced according to their position in the
structure (that is, the value of "i", which is the order in which
the chunk was either read from the input file or defined with
png_set_unknown_chunks).
A quick word about text and num_text. text is an array of png_text
structures. num_text is the number of valid structures in the array.
Each png_text structure holds a language code, a keyword, a text value,
and a compression type.
The compression types have the same valid numbers as the compression
types of the image data. Currently, the only valid number is zero.
However, you can store text either compressed or uncompressed, unlike
images, which always have to be compressed. So if you don't want the
text compressed, set the compression type to PNG_TEXT_COMPRESSION_NONE.
Because tEXt and zTXt chunks don't have a language field, if you
specify PNG_TEXT_COMPRESSION_NONE or PNG_TEXT_COMPRESSION_zTXt
any language code or translated keyword will not be written out.
Until text gets around a few hundred bytes, it is not worth compressing it.
After the text has been written out to the file, the compression type
is set to PNG_TEXT_COMPRESSION_NONE_WR or PNG_TEXT_COMPRESSION_zTXt_WR,
so that it isn't written out again at the end (in case you are calling
png_write_end() with the same struct).
The keywords that are given in the PNG Specification are:
Title Short (one line) title or
caption for image
Author Name of image's creator
Description Description of image (possibly long)
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
words, not abbreviations. Keywords and text are in the ISO 8859-1
(Latin-1) character set (a superset of regular ASCII) and can not
contain NUL characters, and should not contain control or other
unprintable characters. To make the comments widely readable, stick
with basic ASCII, and avoid machine specific character set extensions
like the IBM-PC character set. The keyword must be present, but
you can leave off the text string on non-compressed pairs.
Compressed pairs must have a text string, as only the text string
is compressed anyway, so the compression would be meaningless.
PNG supports modification time via the png_time structure. Two
conversion routines are provided, png_convert_from_time_t() for
time_t and png_convert_from_struct_tm() for struct tm. The
time_t routine uses gmtime(). You don't have to use either of
these, but if you wish to fill in the png_time structure directly,
you should provide the time in universal time (GMT) if possible
instead of your local time. Note that the year number is the full
year (e.g. 1998, rather than 98 - PNG is year 2000 compliant!), and
that months start with 1.
If you want to store the time of the original image creation, you should
use a plain tEXt chunk with the "Creation Time" keyword. This is
necessary because the "creation time" of a PNG image is somewhat vague,
depending on whether you mean the PNG file, the time the image was
created in a non-PNG format, a still photo from which the image was
scanned, or possibly the subject matter itself. In order to facilitate
machine-readable dates, it is recommended that the "Creation Time"
tEXt chunk use RFC 1123 format dates (e.g. "22 May 1997 18:07:10 GMT"),
although this isn't a requirement. Unlike the tIME chunk, the
"Creation Time" tEXt chunk is not expected to be automatically changed
by the software. To facilitate the use of RFC 1123 dates, a function
png_convert_to_rfc1123_buffer(buffer, png_timep) is provided to
convert from PNG time to an RFC 1123 format string. The caller must provide
a writeable buffer of at least 29 bytes.
Writing unknown chunks
You can use the png_set_unknown_chunks function to queue up private chunks
for writing. You give it a chunk name, location, raw data, and a size. You
also must use png_set_keep_unknown_chunks() to ensure that libpng will
handle them. That's all there is to it. The chunks will be written by the
next following png_write_info_before_PLTE, png_write_info, or png_write_end
function, depending upon the specified location. Any chunks previously
read into the info structure's unknown-chunk list will also be written out
in a sequence that satisfies the PNG specification's ordering rules.
Here is an example of writing two private chunks, prVt and miNE:
#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
/* Set unknown chunk data */
png_unknown_chunk unk_chunk[2];
strcpy((char *) unk_chunk[0].name, "prVt";
unk_chunk[0].data = (unsigned char *) "PRIVATE DATA";
unk_chunk[0].size = strlen(unk_chunk[0].data)+1;
unk_chunk[0].location = PNG_HAVE_IHDR;
strcpy((char *) unk_chunk[1].name, "miNE";
unk_chunk[1].data = (unsigned char *) "MY CHUNK DATA";
unk_chunk[1].size = strlen(unk_chunk[0].data)+1;
unk_chunk[1].location = PNG_AFTER_IDAT;
png_set_unknown_chunks(write_ptr, write_info_ptr,
unk_chunk, 2);
/* Needed because miNE is not safe-to-copy */
png_set_keep_unknown_chunks(png, PNG_HANDLE_CHUNK_ALWAYS,
(png_bytep) "miNE", 1);
# if PNG_LIBPNG_VER < 10600
/* Deal with unknown chunk location bug in 1.5.x and earlier */
png_set_unknown_chunk_location(png, info, 0, PNG_HAVE_IHDR);
png_set_unknown_chunk_location(png, info, 1, PNG_AFTER_IDAT);
# endif
# if PNG_LIBPNG_VER < 10500
/* PNG_AFTER_IDAT writes two copies of the chunk prior to libpng-1.5.0,
* one before IDAT and another after IDAT, so don't use it; only use
* PNG_HAVE_IHDR location. This call resets the location previously
* set by assignment and png_set_unknown_chunk_location() for chunk 1.
*/
png_set_unknown_chunk_location(png, info, 1, PNG_HAVE_IHDR);
# endif
#endif
The high-level write interface
At this point there are two ways to proceed; through the high-level
write interface, or through a sequence of low-level write operations.
You can use the high-level interface if your image data is present
in the info structure. All defined output
transformations are permitted, enabled by the following masks.
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
to transparency
PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
PNG_TRANSFORM_STRIP_FILLER Strip out filler
bytes (deprecated).
PNG_TRANSFORM_STRIP_FILLER_BEFORE Strip out leading
filler bytes
PNG_TRANSFORM_STRIP_FILLER_AFTER Strip out trailing
filler bytes
If you have valid image data in the info structure (you can use
png_set_rows() to put image data in the info structure), simply do this:
png_write_png(png_ptr, info_ptr, png_transforms, NULL)
where png_transforms is an integer containing the bitwise OR of some set of
transformation flags. This call is equivalent to png_write_info(),
followed the set of transformations indicated by the transform mask,
then png_write_image(), and finally png_write_end().
(The final parameter of this call is not yet used. Someday it might point
to transformation parameters required by some future output transform.)
You must use png_transforms and not call any png_set_transform() functions
when you use png_write_png().
The low-level write interface
If you are going the low-level route instead, you are now ready to
write all the file information up to the actual image data. You do
this with a call to png_write_info().
png_write_info(png_ptr, info_ptr);
Note that there is one transformation you may need to do before
png_write_info(). In PNG files, the alpha channel in an image is the
level of opacity. If your data is supplied as a level of transparency,
you can invert the alpha channel before you write it, so that 0 is
fully transparent and 255 (in 8-bit or paletted images) or 65535
(in 16-bit images) is fully opaque, with
png_set_invert_alpha(png_ptr);
This must appear before png_write_info() instead of later with the
other transformations because in the case of paletted images the tRNS
chunk data has to be inverted before the tRNS chunk is written. If
your image is not a paletted image, the tRNS data (which in such cases
represents a single color to be rendered as transparent) won't need to
be changed, and you can safely do this transformation after your
png_write_info() call.
If you need to write a private chunk that you want to appear before
the PLTE chunk when PLTE is present, you can write the PNG info in
two steps, and insert code to write your own chunk between them:
png_write_info_before_PLTE(png_ptr, info_ptr);
png_set_unknown_chunks(png_ptr, info_ptr, ...);
png_write_info(png_ptr, info_ptr);
After you've written the file information, you can set up the library
to handle any special transformations of the image data. The various
ways to transform the data will be described in the order that they
should occur. This is important, as some of these change the color
type and/or bit depth of the data, and some others only work on
certain color types and bit depths. Even though each transformation
checks to see if it has data that it can do something with, you should
make sure to only enable a transformation if it will be valid for the
data. For example, don't swap red and blue on grayscale data.
PNG files store RGB pixels packed into 3 or 6 bytes. This code tells
the library to strip input data that has 4 or 8 bytes per pixel down
to 3 or 6 bytes (or strip 2 or 4-byte grayscale+filler data to 1 or 2
bytes per pixel).
png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
where the 0 is unused, and the location is either PNG_FILLER_BEFORE or
PNG_FILLER_AFTER, depending upon whether the filler byte in the pixel
is stored XRGB or RGBX.
PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
they can, resulting in, for example, 8 pixels per byte for 1 bit files.
If the data is supplied at 1 pixel per byte, use this code, which will
correctly pack the pixels into a single byte:
png_set_packing(png_ptr);
PNG files reduce possible bit depths to 1, 2, 4, 8, and 16. If your
data is of another bit depth, you can write an sBIT chunk into the
file so that decoders can recover the original data if desired.
/* Set the true bit depth of the image data */
if (color_type & PNG_COLOR_MASK_COLOR)
{
sig_bit.red = true_bit_depth;
sig_bit.green = true_bit_depth;
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
else
{
sig_bit.gray = true_bit_depth;
}
if (color_type & PNG_COLOR_MASK_ALPHA)
{
sig_bit.alpha = true_bit_depth;
}
png_set_sBIT(png_ptr, info_ptr, &sig_bit);
If the data is stored in the row buffer in a bit depth other than
one supported by PNG (e.g. 3 bit data in the range 0-7 for a 4-bit PNG),
this will scale the values to appear to be the correct bit depth as
is required by PNG.
png_set_shift(png_ptr, &sig_bit);
PNG files store 16-bit pixels in network byte order (big-endian,
ie. most significant bits first). This code would be used if they are
supplied the other way (little-endian, i.e. least significant bits
first, the way PCs store them):
if (bit_depth > 8)
png_set_swap(png_ptr);
If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
need to change the order the pixels are packed into bytes, you can use:
if (bit_depth < 8)
png_set_packswap(png_ptr);
PNG files store 3 color pixels in red, green, blue order. This code
would be used if they are supplied as blue, green, red:
png_set_bgr(png_ptr);
PNG files describe monochrome as black being zero and white being
one. This code would be used if the pixels are supplied with this reversed
(black being one and white being zero):
png_set_invert_mono(png_ptr);
Finally, you can write your own transformation function if none of
the existing ones meets your needs. This is done by setting a callback
with
png_set_write_user_transform_fn(png_ptr,
write_transform_fn);
You must supply the function
void write_transform_fn(png_structp png_ptr, png_row_infop
row_info, png_bytep data)
See pngtest.c for a working example. Your function will be called
before any of the other transformations are processed. If supported
libpng also supplies an information routine that may be called from
your callback:
png_get_current_row_number(png_ptr);
png_get_current_pass_number(png_ptr);
This returns the current row passed to the transform. With interlaced
images the value returned is the row in the input sub-image image. Use
PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass).
The discussion of interlace handling above contains more information on how to
use these values.
You can also set up a pointer to a user structure for use by your
callback function.
png_set_user_transform_info(png_ptr, user_ptr, 0, 0);
The user_channels and user_depth parameters of this function are ignored
when writing; you can set them to zero as shown.
You can retrieve the pointer via the function png_get_user_transform_ptr().
For example:
voidp write_user_transform_ptr =
png_get_user_transform_ptr(png_ptr);
It is possible to have libpng flush any pending output, either manually,
or automatically after a certain number of lines have been written. To
flush the output stream a single time call:
png_write_flush(png_ptr);
and to have libpng flush the output stream periodically after a certain
number of scanlines have been written, call:
png_set_flush(png_ptr, nrows);
Note that the distance between rows is from the last time png_write_flush()
was called, or the first row of the image if it has never been called.
So if you write 50 lines, and then png_set_flush 25, it will flush the
output on the next scanline, and every 25 lines thereafter, unless
png_write_flush() is called before 25 more lines have been written.
If nrows is too small (less than about 10 lines for a 640 pixel wide
RGB image) the image compression may decrease noticeably (although this
may be acceptable for real-time applications). Infrequent flushing will
only degrade the compression performance by a few percent over images
that do not use flushing.
Writing the image data
That's it for the transformations. Now you can write the image data.
The simplest way to do this is in one function call. If you have the
whole image in memory, you can just call png_write_image() and libpng
will write the image. You will need to pass in an array of pointers to
each row. This function automatically handles interlacing, so you don't
need to call png_set_interlace_handling() or call this function multiple
times, or any of that other stuff necessary with png_write_rows().
png_write_image(png_ptr, row_pointers);
where row_pointers is:
png_byte *row_pointers[height];
You can point to void or char or whatever you use for pixels.
If you don't want to write the whole image at once, you can
use png_write_rows() instead. If the file is not interlaced,
this is simple:
png_write_rows(png_ptr, row_pointers,
number_of_rows);
row_pointers is the same as in the png_write_image() call.
If you are just writing one row at a time, you can do this with
a single row_pointer instead of an array of row_pointers:
png_bytep row_pointer = row;
png_write_row(png_ptr, row_pointer);
When the file is interlaced, things can get a good deal more complicated.
The only currently (as of the PNG Specification version 1.2, dated July
1999) defined interlacing scheme for PNG files is the "Adam7" interlace
scheme, that breaks down an image into seven smaller images of varying
size. libpng will build these images for you, or you can do them
yourself. If you want to build them yourself, see the PNG specification
for details of which pixels to write when.
If you don't want libpng to handle the interlacing details, just
use png_set_interlace_handling() and call png_write_rows() the
correct number of times to write all the sub-images
(png_set_interlace_handling() returns the number of sub-images.)
If you want libpng to build the sub-images, call this before you start
writing any rows:
number_of_passes = png_set_interlace_handling(png_ptr);
This will return the number of passes needed. Currently, this is seven,
but may change if another interlace type is added.
Then write the complete image number_of_passes times.
png_write_rows(png_ptr, row_pointers, number_of_rows);
Think carefully before you write an interlaced image. Typically code that
reads such images reads all the image data into memory, uncompressed, before
doing any processing. Only code that can display an image on the fly can
take advantage of the interlacing and even then the image has to be exactly
the correct size for the output device, because scaling an image requires
adjacent pixels and these are not available until all the passes have been
read.
If you do write an interlaced image you will hardly ever need to handle
the interlacing yourself. Call png_set_interlace_handling() and use the
approach described above.
The only time it is conceivable that you will really need to write an
interlaced image pass-by-pass is when you have read one pass by pass and
made some pixel-by-pixel transformation to it, as described in the read
code above. In this case use the PNG_PASS_ROWS and PNG_PASS_COLS macros
to determine the size of each sub-image in turn and simply write the rows
you obtained from the read code.
Finishing a sequential write
After you are finished writing the image, you should finish writing
the file. If you are interested in writing comments or time, you should
pass an appropriately filled png_info pointer. If you are not interested,
you can pass NULL.
png_write_end(png_ptr, info_ptr);
When you are done, you can free all memory used by libpng like this:
png_destroy_write_struct(&png_ptr, &info_ptr);
It is also possible to individually free the info_ptr members that
point to libpng-allocated storage with the following function:
png_free_data(png_ptr, info_ptr, mask, seq)
mask - identifies data to be freed, a mask
containing the bitwise OR of one or
more of
PNG_FREE_PLTE, PNG_FREE_TRNS,
PNG_FREE_HIST, PNG_FREE_ICCP,
PNG_FREE_PCAL, PNG_FREE_ROWS,
PNG_FREE_SCAL, PNG_FREE_SPLT,
PNG_FREE_TEXT, PNG_FREE_UNKN,
or simply PNG_FREE_ALL
seq - sequence number of item to be freed
(-1 for all items)
This function may be safely called when the relevant storage has
already been freed, or has not yet been allocated, or was allocated
by the user and not by libpng, and will in those cases do nothing.
The "seq" parameter is ignored if only one item of the selected data
type, such as PLTE, is allowed. If "seq" is not -1, and multiple items
are allowed for the data type identified in the mask, such as text or
sPLT, only the n'th item in the structure is freed, where n is "seq".
If you allocated data such as a palette that you passed in to libpng
with png_set_*, you must not free it until just before the call to
png_destroy_write_struct().
The default behavior is only to free data that was allocated internally
by libpng. This can be changed, so that libpng will not free the data,
or so that it will free data that was allocated by the user with png_malloc()
or png_calloc() and passed in via a png_set_*() function, with
png_data_freer(png_ptr, info_ptr, freer, mask)
freer - one of
PNG_DESTROY_WILL_FREE_DATA
PNG_SET_WILL_FREE_DATA
PNG_USER_WILL_FREE_DATA
mask - which data elements are affected
same choices as in png_free_data()
For example, to transfer responsibility for some data from a read structure
to a write structure, you could use
png_data_freer(read_ptr, read_info_ptr,
PNG_USER_WILL_FREE_DATA,
PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
png_data_freer(write_ptr, write_info_ptr,
PNG_DESTROY_WILL_FREE_DATA,
PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
thereby briefly reassigning responsibility for freeing to the user but
immediately afterwards reassigning it once more to the write_destroy
function. Having done this, it would then be safe to destroy the read
structure and continue to use the PLTE, tRNS, and hIST data in the write
structure.
This function only affects data that has already been allocated.
You can call this function before calling after the png_set_*() functions
to control whether the user or png_destroy_*() is supposed to free the data.
When the user assumes responsibility for libpng-allocated data, the
application must use
png_free() to free it, and when the user transfers responsibility to libpng
for data that the user has allocated, the user must have used png_malloc()
or png_calloc() to allocate it.
If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
separately, do not transfer responsibility for freeing text_ptr to libpng,
because when libpng fills a png_text structure it combines these members with
the key member, and png_free_data() will free only text_ptr.key. Similarly,
if you transfer responsibility for free'ing text_ptr from libpng to your
application, your application must not separately free those members.
For a more compact example of writing a PNG image, see the file example.c.
V. Simplified API
The simplified API, which became available in libpng-1.6.0, hides the details
of both libpng and the PNG file format itself.
It allows PNG files to be read into a very limited number of
in-memory bitmap formats or to be written from the same formats. If these
formats do not accommodate your needs then you can, and should, use the more
sophisticated APIs above - these support a wide variety of in-memory formats
and a wide variety of sophisticated transformations to those formats as well
as a wide variety of APIs to manipulate ancilliary information.
To read a PNG file using the simplified API:
1) Declare a 'png_image' structure (see below) on the
stack and memset() it to all zero.
2) Call the appropriate png_image_begin_read... function.
3) Set the png_image 'format' member to the required
format and allocate a buffer for the image.
4) Call png_image_finish_read to read the image into
your buffer.
There are no restrictions on the format of the PNG input itself; all valid
color types, bit depths, and interlace methods are acceptable, and the
input image is transformed as necessary to the requested in-memory format
during the png_image_finish_read() step.
To write a PNG file using the simplified API:
1) Declare a 'png_image' structure on the stack and memset()
it to all zero.
2) Initialize the members of the structure that describe the
image, setting the 'format' member to the format of the
image in memory.
3) Call the appropriate png_image_write... function with a
pointer to the image to write the PNG data.
png_image is a structure that describes the in-memory format of an image
when it is being read or define the in-memory format of an image that you
need to write. The "png_image" structure contains the following members:
png_uint_32 version Set to PNG_IMAGE_VERSION
png_uint_32 width Image width in pixels (columns)
png_uint_32 height Image height in pixels (rows)
png_uint_32 format Image format as defined below
png_uint_32 flags A bit mask containing informational flags
png_controlp opaque Initialize to NULL, free with png_image_free
png_uint_32 colormap_entries; Number of entries in the color-map
png_uint_32 warning_or_error;
char message[64];
In the event of an error or warning the following field warning_or_error
field will be set to a non-zero value and the 'message' field will contain
a '\0' terminated string with the libpng error or warning message. If both
warnings and an error were encountered, only the error is recorded. If there
are multiple warnings, only the first one is recorded.
The upper 30 bits of this value are reserved; the low two bits contain
a two bit code such that a value more than 1 indicates a failure in the API
just called:
0 - no warning or error
1 - warning
2 - error
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
channels are linear. Color channels use the RGB encoding (RGB end-points) of
the sRGB specification. This encoding is identified by the
PNG_FORMAT_FLAG_LINEAR flag below.
When an alpha channel is present it is expected to denote pixel coverage
of the color or luminance channels and is returned as an associated alpha
channel: the color/gray channels are scaled (pre-multiplied) by the alpha
value.
When a color-mapped image is used as a result of calling
png_image_read_colormap or png_image_write_colormap the channels are encoded
in the color-map and the descriptions above apply to the color-map entries.
The image data is encoded as small integers, value 0..255, that index the
entries in the color-map. One integer (one byte) is stored for each pixel.
PNG_FORMAT_*
The #defines to be used in png_image::format. Each #define identifies a
particular layout of channel data and, if present, alpha values. There are
separate defines for each of the two channel encodings.
A format is built up using single bit flag values. Not all combinations are
valid: use the bit flag values below for testing a format returned by the
read APIs, but set formats from the derived values.
When reading or writing color-mapped images the format should be set to the
format of the entries in the color-map then png_image_{read,write}_colormap
called to read or write the color-map and set the format correctly for the
image data. Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly!
NOTE: libpng can be built with particular features disabled, if you see
compiler errors because the definition of one of the following flags has been
compiled out it is because libpng does not have the required support. It is
possible, however, for the libpng configuration to enable the format on just
read or just write; in that case you may see an error at run time. You can
guard against this by checking for the definition of:
PNG_SIMPLIFIED_{READ,WRITE}_{BGR,AFIRST}_SUPPORTED
PNG_FORMAT_FLAG_ALPHA 0x01 format with an alpha channel
PNG_FORMAT_FLAG_COLOR 0x02 color format: otherwise grayscale
PNG_FORMAT_FLAG_LINEAR 0x04 png_uint_16 channels else png_byte
PNG_FORMAT_FLAG_COLORMAP 0x08 libpng use only
PNG_FORMAT_FLAG_BGR 0x10 BGR colors, else order is RGB
PNG_FORMAT_FLAG_AFIRST 0x20 alpha channel comes first
Supported formats are as follows. Future versions of libpng may support more
formats; for compatibility with older versions simply check if the format
macro is defined using #ifdef. These defines describe the in-memory layout
of the components of the pixels of the image.
First the single byte formats:
PNG_FORMAT_GRAY 0
PNG_FORMAT_GA PNG_FORMAT_FLAG_ALPHA
PNG_FORMAT_AG (PNG_FORMAT_GA|PNG_FORMAT_FLAG_AFIRST)
PNG_FORMAT_RGB PNG_FORMAT_FLAG_COLOR
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
PNG_FORMAT_LINEAR_Y PNG_FORMAT_FLAG_LINEAR
PNG_FORMAT_LINEAR_Y_ALPHA
(PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_ALPHA)
PNG_FORMAT_LINEAR_RGB
(PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR)
PNG_FORMAT_LINEAR_RGB_ALPHA
(PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR|
PNG_FORMAT_FLAG_ALPHA)
Color-mapped formats are obtained by calling png_image_{read,write}_colormap,
as appropriate after setting png_image::format to the format of the color-map
to be read or written. Applications may check the value of
PNG_FORMAT_FLAG_COLORMAP to see if they have called the colormap API. The
format of the color-map may be extracted using the following macro.
PNG_FORMAT_OF_COLORMAP(fmt) ((fmt) & ~PNG_FORMAT_FLAG_COLORMAP)
PNG_IMAGE macros
These are convenience macros to derive information from a png_image
structure. The PNG_IMAGE_SAMPLE_ macros return values appropriate to the
actual image sample values - either the entries in the color-map or the
pixels in the image. The PNG_IMAGE_PIXEL_ macros return corresponding values
for the pixels and will always return 1 after a call to
png_image_{read,write}_colormap. The remaining macros return information
about the rows in the image and the complete image.
NOTE: All the macros that take a png_image::format parameter are compile time
constants if the format parameter is, itself, a constant. Therefore these
macros can be used in array declarations and case labels where required.
Similarly the macros are also pre-processor constants (sizeof is not used) so
they can be used in #if tests.
First the information about the samples.
PNG_IMAGE_SAMPLE_CHANNELS(fmt)
Returns the total number of channels in a given format: 1..4
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
Returns the size in bytes of a single component of a pixel or color-map
entry (as appropriate) in the image.
PNG_IMAGE_SAMPLE_SIZE(fmt)
This is the size of the sample data for one sample. If the image is
color-mapped it is the size of one color-map entry (and image pixels are
one byte in size), otherwise it is the size of one image pixel.
PNG_IMAGE_COLORMAP_SIZE(fmt)
The size of the color-map required by the format; this is the size of the
color-map buffer passed to the png_image_{read,write}_colormap APIs, it is
a fixed number determined by the format so can easily be allocated on the
stack if necessary.
#define PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)\
(PNG_IMAGE_SAMPLE_CHANNELS(fmt) * 256)
/* The maximum size of the color-map required by the format expressed in a
* count of components. This can be used to compile-time allocate a
* color-map:
*
* png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
*
* png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
*
* Alternatively, use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
* information from one of the png_image_begin_read_ APIs and dynamically
* allocate the required memory.
*/
Corresponding information about the pixels
PNG_IMAGE_PIXEL_(test,fmt)
PNG_IMAGE_PIXEL_CHANNELS(fmt)
The number of separate channels (components) in a pixel; 1 for a
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
is the minimum 'row stride', the minimum count of components between each
row. For a color-mapped image this is the minimum number of bytes in a
row.
If you need the stride measured in bytes, row_stride_bytes is
PNG_IMAGE_ROW_STRIDE(image) * PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)
plus any padding bytes that your application might need, for example
to start the next row on a 4-byte boundary.
PNG_IMAGE_BUFFER_SIZE(image, row_stride)
Returns the size, in bytes, of an image buffer given a png_image and a row
stride - the number of components to leave space for in each row. This
macro takes care of multiplying row_stride by PNG_IMAGE_PIXEL_COMONENT_SIZE
when the image has 2-byte components.
PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB == 0x01
This indicates the the RGB values of the in-memory bitmap do not
correspond to the red, green and blue end-points defined by sRGB.
PNG_IMAGE_FLAG_COLORMAP == 0x02
The PNG is color-mapped. If this flag is set png_image_read_colormap
can be used without further loss of image information. If it is not set
png_image_read_colormap will cause significant loss if the image has any
READ APIs
The png_image passed to the read APIs must have been initialized by setting
the png_controlp field 'opaque' to NULL (or, better, memset the whole thing.)
int png_image_begin_read_from_file( png_imagep image,
const char *file_name)
The named file is opened for read and the image header
is filled in from the PNG header in the file.
int png_image_begin_read_from_stdio (png_imagep image,
FILE* file)
The PNG header is read from the stdio FILE object.
int png_image_begin_read_from_memory(png_imagep image,
png_const_voidp memory, png_size_t size)
The PNG header is read from the given memory buffer.
int png_image_finish_read(png_imagep image,
png_colorp background, void *buffer,
png_int_32 row_stride, void *colormap));
Finish reading the image into the supplied buffer and
clean up the png_image structure.
row_stride is the step, in png_byte or png_uint_16 units
as appropriate, between adjacent rows. A positive stride
indicates that the top-most row is first in the buffer -
the normal top-down arrangement. A negative stride
indicates that the bottom-most row is first in the buffer.
background need only be supplied if an alpha channel must
be removed from a png_byte format and the removal is to be
done by compositing on a solid color; otherwise it may be
NULL and any composition will be done directly onto the
buffer. The value is an sRGB color to use for the
background, for grayscale output the green channel is used.
For linear output removing the alpha channel is always done
by compositing on black.
void png_image_free(png_imagep image)
Free any data allocated by libpng in image->opaque,
setting the pointer to NULL. May be called at any time
after the structure is initialized.
When the simplified API needs to convert between sRGB and linear colorspaces,
the actual sRGB transfer curve defined in the sRGB specification (see the
article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
approximation used elsewhere in libpng.
WRITE APIS
For write you must initialize a png_image structure to describe the image to
be written:
version: must be set to PNG_IMAGE_VERSION
opaque: must be initialized to NULL
width: image width in pixels
height: image height in rows
format: the format of the data you wish to write
flags: set to 0 unless one of the defined flags applies; set
PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB for color format images
where the RGB values do not correspond to the colors in sRGB.
colormap_entries: set to the number of entries in the color-map (0 to 256)
int png_image_write_to_file, (png_imagep image,
const char *file, int convert_to_8bit, const void *buffer,
png_int_32 row_stride, const void *colormap));
Write the image to the named file.
int png_image_write_to_stdio(png_imagep image, FILE *file,
int convert_to_8_bit, const void *buffer,
png_int_32 row_stride, const void *colormap)
Write the image to the given (FILE*).
With all write APIs if image is in one of the linear formats with
(png_uint_16) data then setting convert_to_8_bit will cause the output to be
a (png_byte) PNG gamma encoded according to the sRGB specification, otherwise
a 16-bit linear encoded PNG file is written.
With all APIs row_stride is handled as in the read APIs - it is the spacing
from one row to the next in component sized units (float) and if negative
indicates a bottom-up row layout in the buffer.
Note that the write API does not support interlacing, sub-8-bit pixels,
and indexed (paletted) images.
VI. Modifying/Customizing libpng
There are two issues here. The first is changing how libpng does
standard things like memory allocation, input/output, and error handling.
The second deals with more complicated things like adding new chunks,
adding new transformations, and generally changing how libpng works.
Both of those are compile-time issues; that is, they are generally
determined at the time the code is written, and there is rarely a need
to provide the user with a means of changing them.
Memory allocation, input/output, and error handling
All of the memory allocation, input/output, and error handling in libpng
goes through callbacks that are user-settable. The default routines are
in pngmem.c, pngrio.c, pngwio.c, and pngerror.c, respectively. To change
these functions, call the appropriate png_set_*_fn() function.
Memory allocation is done through the functions png_malloc(), png_calloc(),
and png_free(). The png_malloc() and png_free() functions currently just
call the standard C functions and png_calloc() calls png_malloc() and then
clears the newly allocated memory to zero; note that png_calloc(png_ptr, size)
is not the same as the calloc(number, size) function provided by stdlib.h.
There is limited support for certain systems with segmented memory
architectures and the types of pointers declared by png.h match this; you
will have to use appropriate pointers in your application. If you prefer
to use a different method of allocating and freeing data, you can use
png_create_read_struct_2() or png_create_write_struct_2() to register your
own functions as described above. These functions also provide a void
pointer that can be retrieved via
mem_ptr=png_get_mem_ptr(png_ptr);
Your replacement memory functions must have prototypes as follows:
png_voidp malloc_fn(png_structp png_ptr,
png_alloc_size_t size);
void free_fn(png_structp png_ptr, png_voidp ptr);
Your malloc_fn() must return NULL in case of failure. The png_malloc()
function will normally call png_error() if it receives a NULL from the
system memory allocator or from your replacement malloc_fn().
Your free_fn() will never be called with a NULL ptr, since libpng's
png_free() checks for NULL before calling free_fn().
Input/Output in libpng is done through png_read() and png_write(),
which currently just call fread() and fwrite(). The FILE * is stored in
png_struct and is initialized via png_init_io(). If you wish to change
the method of I/O, the library supplies callbacks that you can set
through the function png_set_read_fn() and png_set_write_fn() at run
time, instead of calling the png_init_io() function. These functions
also provide a void pointer that can be retrieved via the function
png_get_io_ptr(). For example:
png_set_read_fn(png_structp read_ptr,
voidp read_io_ptr, png_rw_ptr read_data_fn)
png_set_write_fn(png_structp write_ptr,
voidp write_io_ptr, png_rw_ptr write_data_fn,
png_flush_ptr output_flush_fn);
voidp read_io_ptr = png_get_io_ptr(read_ptr);
voidp write_io_ptr = png_get_io_ptr(write_ptr);
The replacement I/O functions must have prototypes as follows:
void user_read_data(png_structp png_ptr,
png_bytep data, png_size_t length);
void user_write_data(png_structp png_ptr,
png_bytep data, png_size_t length);
void user_flush_data(png_structp png_ptr);
The user_read_data() function is responsible for detecting and
handling end-of-data errors.
Supplying NULL for the read, write, or flush functions sets them back
to using the default C stream functions, which expect the io_ptr to
point to a standard *FILE structure. It is probably a mistake
to use NULL for one of write_data_fn and output_flush_fn but not both
of them, unless you have built libpng with PNG_NO_WRITE_FLUSH defined.
It is an error to read from a write stream, and vice versa.
Error handling in libpng is done through png_error() and png_warning().
Errors handled through png_error() are fatal, meaning that png_error()
should never return to its caller. Currently, this is handled via
setjmp() and longjmp() (unless you have compiled libpng with
PNG_NO_SETJMP, in which case it is handled via PNG_ABORT()),
but you could change this to do things like exit() if you should wish,
as long as your function does not return.
On non-fatal errors, png_warning() is called
to print a warning message, and then control returns to the calling code.
By default png_error() and png_warning() print a message on stderr via
fprintf() unless the library is compiled with PNG_NO_CONSOLE_IO defined
(because you don't want the messages) or PNG_NO_STDIO defined (because
fprintf() isn't available). If you wish to change the behavior of the error
functions, you will need to set up your own message callbacks. These
functions are normally supplied at the time that the png_struct is created.
It is also possible to redirect errors and warnings to your own replacement
functions after png_create_*_struct() has been called by calling:
png_set_error_fn(png_structp png_ptr,
png_voidp error_ptr, png_error_ptr error_fn,
png_error_ptr warning_fn);
png_voidp error_ptr = png_get_error_ptr(png_ptr);
If NULL is supplied for either error_fn or warning_fn, then the libpng
default function will be used, calling fprintf() and/or longjmp() if a
problem is encountered. The replacement error functions should have
parameters as follows:
void user_error_fn(png_structp png_ptr,
png_const_charp error_msg);
void user_warning_fn(png_structp png_ptr,
png_const_charp warning_msg);
The motivation behind using setjmp() and longjmp() is the C++ throw and
catch exception handling methods. This makes the code much easier to write,
as there is no need to check every return code of every function call.
However, there are some uncertainties about the status of local variables
after a longjmp, so the user may want to be careful about doing anything
after setjmp returns non-zero besides returning itself. Consult your
compiler documentation for more details. For an alternative approach, you
may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net),
which is illustrated in pngvalid.c and in contrib/visupng.
Beginning in libpng-1.4.0, the png_set_benign_errors() API became available.
You can use this to handle certain errors (normally handled as errors)
as warnings.
png_set_benign_errors (png_ptr, int allowed);
allowed: 0: treat png_benign_error() as an error.
1: treat png_benign_error() as a warning.
As of libpng-1.6.0, the default condition is to treat benign errors as
warnings while reading and as errors while writing.
Custom chunks
If you need to read or write custom chunks, you may need to get deeper
into the libpng code. The library now has mechanisms for storing
and writing chunks of unknown type; you can even declare callbacks
for custom chunks. However, this may not be good enough if the
library code itself needs to know about interactions between your
chunk and existing `intrinsic' chunks.
If you need to write a new intrinsic chunk, first read the PNG
specification. Acquire a first level of understanding of how it works.
Pay particular attention to the sections that describe chunk names,
and look at how other chunks were designed, so you can do things
similarly. Second, check out the sections of libpng that read and
write chunks. Try to find a chunk that is similar to yours and use
it as a template. More details can be found in the comments inside
the code. It is best to handle private or unknown chunks in a generic method,
via callback functions, instead of by modifying libpng functions. This
is illustrated in pngtest.c, which uses a callback function to handle a
private "vpAg" chunk and the new "sTER" chunk, which are both unknown to
libpng.
If you wish to write your own transformation for the data, look through
the part of the code that does the transformations, and check out some of
the simpler ones to get an idea of how they work. Try to find a similar
transformation to the one you want to add and copy off of it. More details
can be found in the comments inside the code itself.
Configuring for gui/windowing platforms:
You will need to write new error and warning functions that use the GUI
interface, as described previously, and set them to be the error and
warning functions at the time that png_create_*_struct() is called,
in order to have them available during the structure initialization.
They can be changed later via png_set_error_fn(). On some compilers,
you may also have to change the memory allocators (png_malloc, etc.).
Configuring zlib:
There are special functions to configure the compression. Perhaps the
most useful one changes the compression level, which currently uses
input compression values in the range 0 - 9. The library normally
uses the default compression level (Z_DEFAULT_COMPRESSION = 6). Tests
have shown that for a large majority of images, compression values in
the range 3-6 compress nearly as well as higher levels, and do so much
faster. For online applications it may be desirable to have maximum speed
(Z_BEST_SPEED = 1). With versions of zlib after v0.99, you can also
specify no compression (Z_NO_COMPRESSION = 0), but this would create
files larger than just storing the raw bitmap. You can specify the
compression level by calling:
#include zlib.h
png_set_compression_level(png_ptr, level);
Another useful one is to reduce the memory level used by the library.
The memory level defaults to 8, but it can be lowered if you are
short on memory (running DOS, for example, where you only have 640K).
Note that the memory level does have an effect on compression; among
other things, lower levels will result in sections of incompressible
data being emitted in smaller stored blocks, with a correspondingly
larger relative overhead of up to 15% in the worst case.
#include zlib.h
png_set_compression_mem_level(png_ptr, level);
The other functions are for configuring zlib. They are not recommended
for normal use and may result in writing an invalid PNG file. See
zlib.h for more information on what these mean.
#include zlib.h
png_set_compression_strategy(png_ptr,
strategy);
png_set_compression_window_bits(png_ptr,
window_bits);
png_set_compression_method(png_ptr, method);
This controls the size of the IDAT chunks (default 8192):
png_set_compression_buffer_size(png_ptr, size);
As of libpng version 1.5.4, additional APIs became
available to set these separately for non-IDAT
compressed chunks such as zTXt, iTXt, and iCCP:
#include zlib.h
#if PNG_LIBPNG_VER >= 10504
png_set_text_compression_level(png_ptr, level);
png_set_text_compression_mem_level(png_ptr, level);
png_set_text_compression_strategy(png_ptr,
strategy);
png_set_text_compression_window_bits(png_ptr,
window_bits);
png_set_text_compression_method(png_ptr, method);
#endif
Controlling row filtering
If you want to control whether libpng uses filtering or not, which
filters are used, and how it goes about picking row filters, you
can call one of these functions. The selection and configuration
of row filters can have a significant impact on the size and
encoding speed and a somewhat lesser impact on the decoding speed
of an image. Filtering is enabled by default for RGB and grayscale
images (with and without alpha), but not for paletted images nor
for any images with bit depths less than 8 bits/pixel.
The 'method' parameter sets the main filtering method, which is
currently only '0' in the PNG 1.2 specification. The 'filters'
parameter sets which filter(s), if any, should be used for each
scanline. Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS
to turn filtering on and off, respectively.
Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise
ORed together with '|' to specify one or more filters to use.
These filters are described in more detail in the PNG specification.
If you intend to change the filter type during the course of writing
the image, you should start with flags set for all of the filters
you intend to use so that libpng can initialize its internal
structures appropriately for all of the filter types. (Note that this
means the first row must always be adaptively filtered, because libpng
currently does not allocate the filter buffers until png_write_row()
is called for the first time.)
filters = PNG_FILTER_NONE | PNG_FILTER_SUB
PNG_FILTER_UP | PNG_FILTER_AVG |
PNG_FILTER_PAETH | PNG_ALL_FILTERS;
png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
filters);
The second parameter can also be
PNG_INTRAPIXEL_DIFFERENCING if you are
writing a PNG to be embedded in a MNG
datastream. This parameter must be the
same as the value of filter_method used
in png_set_IHDR().
It is also possible to influence how libpng chooses from among the
available filters. This is done in one or both of two ways - by
telling it how important it is to keep the same filter for successive
rows, and by telling it the relative computational costs of the filters.
double weights[3] = {1.5, 1.3, 1.1},
costs[PNG_FILTER_VALUE_LAST] =
{1.0, 1.3, 1.3, 1.5, 1.7};
png_set_filter_heuristics(png_ptr,
PNG_FILTER_HEURISTIC_WEIGHTED, 3,
weights, costs);
The weights are multiplying factors that indicate to libpng that the
row filter should be the same for successive rows unless another row filter
is that many times better than the previous filter. In the above example,
if the previous 3 filters were SUB, SUB, NONE, the SUB filter could have a
"sum of absolute differences" 1.5 x 1.3 times higher than other filters
and still be chosen, while the NONE filter could have a sum 1.1 times
higher than other filters and still be chosen. Unspecified weights are
taken to be 1.0, and the specified weights should probably be declining
like those above in order to emphasize recent filters over older filters.
The filter costs specify for each filter type a relative decoding cost
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
Requesting debug printout
The macro definition PNG_DEBUG can be used to request debugging
printout. Set it to an integer value in the range 0 to 3. Higher
numbers result in increasing amounts of debugging information. The
information is printed to the "stderr" file, unless another file
name is specified in the PNG_DEBUG_FILE macro definition.
When PNG_DEBUG > 0, the following functions (macros) become available:
png_debug(level, message)
png_debug1(level, message, p1)
png_debug2(level, message, p1, p2)
in which "level" is compared to PNG_DEBUG to decide whether to print
the message, "message" is the formatted string to be printed,
and p1 and p2 are parameters that are to be embedded in the string
according to printf-style formatting directives. For example,
png_debug1(2, "foo=%d", foo);
is expanded to
if (PNG_DEBUG > 2)
fprintf(PNG_DEBUG_FILE, "foo=%d\n", foo);
When PNG_DEBUG is defined but is zero, the macros aren't defined, but you
can still use PNG_DEBUG to control your own debugging:
#ifdef PNG_DEBUG
fprintf(stderr, ...
#endif
When PNG_DEBUG = 1, the macros are defined, but only png_debug statements
having level = 0 will be printed. There aren't any such statements in
this version of libpng, but if you insert some they will be printed.
VII. MNG support
The MNG specification (available at http://www.libpng.org/pub/mng) allows
certain extensions to PNG for PNG images that are embedded in MNG datastreams.
Libpng can support some of these extensions. To enable them, use the
png_permit_mng_features() function:
feature_set = png_permit_mng_features(png_ptr, mask)
mask is a png_uint_32 containing the bitwise OR of the
features you want to enable. These include
PNG_FLAG_MNG_EMPTY_PLTE
PNG_FLAG_MNG_FILTER_64
PNG_ALL_MNG_FEATURES
feature_set is a png_uint_32 that is the bitwise AND of
your mask with the set of MNG features that is
supported by the version of libpng that you are using.
It is an error to use this function when reading or writing a standalone
PNG file with the PNG 8-byte signature. The PNG datastream must be wrapped
in a MNG datastream. As a minimum, it must have the MNG 8-byte signature
and the MHDR and MEND chunks. Libpng does not provide support for these
or any other MNG chunks; your application must provide its own support for
them. You may wish to consider using libmng (available at
http://www.libmng.com) instead.
VIII. Changes to Libpng from version 0.88
It should be noted that versions of libpng later than 0.96 are not
distributed by the original libpng author, Guy Schalnat, nor by
Andreas Dilger, who had taken over from Guy during 1996 and 1997, and
distributed versions 0.89 through 0.96, but rather by another member
of the original PNG Group, Glenn Randers-Pehrson. Guy and Andreas are
still alive and well, but they have moved on to other things.
The old libpng functions png_read_init(), png_write_init(),
png_info_init(), png_read_destroy(), and png_write_destroy() have been
moved to PNG_INTERNAL in version 0.95 to discourage their use. These
functions will be removed from libpng version 1.4.0.
The preferred method of creating and initializing the libpng structures is
via the png_create_read_struct(), png_create_write_struct(), and
png_create_info_struct() because they isolate the size of the structures
from the application, allow version error checking, and also allow the
use of custom error handling routines during the initialization, which
the old functions do not. The functions png_read_destroy() and
png_write_destroy() do not actually free the memory that libpng
allocated for these structs, but just reset the data structures, so they
can be used instead of png_destroy_read_struct() and
png_destroy_write_struct() if you feel there is too much system overhead
allocating and freeing the png_struct for each image read.
Setting the error callbacks via png_set_message_fn() before
png_read_init() as was suggested in libpng-0.88 is no longer supported
because this caused applications that do not use custom error functions
to fail if the png_ptr was not initialized to zero. It is still possible
to set the error callbacks AFTER png_read_init(), or to change them with
png_set_error_fn(), which is essentially the same function, but with a new
name to force compilation errors with applications that try to use the old
method.
Support for the sCAL, iCCP, iTXt, and sPLT chunks was added at libpng-1.0.6;
however, iTXt support was not enabled by default.
Starting with version 1.0.7, you can find out which version of the library
you are using at run-time:
png_uint_32 libpng_vn = png_access_version_number();
The number libpng_vn is constructed from the major version, minor
version with leading zero, and release number with leading zero,
(e.g., libpng_vn for version 1.0.7 is 10007).
Note that this function does not take a png_ptr, so you can call it
before you've created one.
You can also check which version of png.h you used when compiling your
application:
png_uint_32 application_vn = PNG_LIBPNG_VER;
IX. Changes to Libpng from version 1.0.x to 1.2.x
Support for user memory management was enabled by default. To
accomplish this, the functions png_create_read_struct_2(),
png_create_write_struct_2(), png_set_mem_fn(), png_get_mem_ptr(),
png_malloc_default(), and png_free_default() were added.
Support for the iTXt chunk has been enabled by default as of
version 1.2.41.
Support for certain MNG features was enabled.
Support for numbered error messages was added. However, we never got
around to actually numbering the error messages. The function
png_set_strip_error_numbers() was added (Note: the prototype for this
function was inadvertently removed from png.h in PNG_NO_ASSEMBLER_CODE
builds of libpng-1.2.15. It was restored in libpng-1.2.36).
The png_malloc_warn() function was added at libpng-1.2.3. This issues
a png_warning and returns NULL instead of aborting when it fails to
acquire the requested memory allocation.
Support for setting user limits on image width and height was enabled
by default. The functions png_set_user_limits(), png_get_user_width_max(),
and png_get_user_height_max() were added at libpng-1.2.6.
The png_set_add_alpha() function was added at libpng-1.2.7.
The function png_set_expand_gray_1_2_4_to_8() was added at libpng-1.2.9.
Unlike png_set_gray_1_2_4_to_8(), the new function does not expand the
tRNS chunk to alpha. The png_set_gray_1_2_4_to_8() function is
deprecated.
A number of macro definitions in support of runtime selection of
assembler code features (especially Intel MMX code support) were
added at libpng-1.2.0:
PNG_ASM_FLAG_MMX_SUPPORT_COMPILED
PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU
PNG_ASM_FLAG_MMX_READ_COMBINE_ROW
PNG_ASM_FLAG_MMX_READ_INTERLACE
PNG_ASM_FLAG_MMX_READ_FILTER_SUB
PNG_ASM_FLAG_MMX_READ_FILTER_UP
PNG_ASM_FLAG_MMX_READ_FILTER_AVG
PNG_ASM_FLAG_MMX_READ_FILTER_PAETH
PNG_ASM_FLAGS_INITIALIZED
PNG_MMX_READ_FLAGS
PNG_MMX_FLAGS
PNG_MMX_WRITE_FLAGS
PNG_MMX_FLAGS
We added the following functions in support of runtime
selection of assembler code features:
png_get_mmx_flagmask()
png_set_mmx_thresholds()
png_get_asm_flags()
png_get_mmx_bitdepth_threshold()
png_get_mmx_rowbytes_threshold()
png_set_asm_flags()
We replaced all of these functions with simple stubs in libpng-1.2.20,
when the Intel assembler code was removed due to a licensing issue.
These macros are deprecated:
PNG_READ_TRANSFORMS_NOT_SUPPORTED
PNG_PROGRESSIVE_READ_NOT_SUPPORTED
PNG_NO_SEQUENTIAL_READ_SUPPORTED
PNG_WRITE_TRANSFORMS_NOT_SUPPORTED
PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED
PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
They have been replaced, respectively, by:
PNG_NO_READ_TRANSFORMS
PNG_NO_PROGRESSIVE_READ
PNG_NO_SEQUENTIAL_READ
PNG_NO_WRITE_TRANSFORMS
PNG_NO_READ_ANCILLARY_CHUNKS
PNG_NO_WRITE_ANCILLARY_CHUNKS
PNG_MAX_UINT was replaced with PNG_UINT_31_MAX. It has been
deprecated since libpng-1.0.16 and libpng-1.2.6.
The function
png_check_sig(sig, num)
was replaced with
!png_sig_cmp(sig, 0, num)
It has been deprecated since libpng-0.90.
The function
png_set_gray_1_2_4_to_8()
which also expands tRNS to alpha was replaced with
png_set_expand_gray_1_2_4_to_8()
which does not. It has been deprecated since libpng-1.0.18 and 1.2.9.
X. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x
Private libpng prototypes and macro definitions were moved from
png.h and pngconf.h into a new pngpriv.h header file.
Functions png_set_benign_errors(), png_benign_error(), and
png_chunk_benign_error() were added.
Support for setting the maximum amount of memory that the application
will allocate for reading chunks was added, as a security measure.
The functions png_set_chunk_cache_max() and png_get_chunk_cache_max()
were added to the library.
We implemented support for I/O states by adding png_ptr member io_state
and functions png_get_io_chunk_name() and png_get_io_state() in pngget.c
We added PNG_TRANSFORM_GRAY_TO_RGB to the available high-level
input transforms.
Checking for and reporting of errors in the IHDR chunk is more thorough.
Support for global arrays was removed, to improve thread safety.
Some obsolete/deprecated macros and functions have been removed.
Typecasted NULL definitions such as
#define png_voidp_NULL (png_voidp)NULL
were eliminated. If you used these in your application, just use
NULL instead.
The png_struct and info_struct members "trans" and "trans_values" were
changed to "trans_alpha" and "trans_color", respectively.
The obsolete, unused pnggccrd.c and pngvcrd.c files and related makefiles
were removed.
The PNG_1_0_X and PNG_1_2_X macros were eliminated.
The PNG_LEGACY_SUPPORTED macro was eliminated.
Many WIN32_WCE #ifdefs were removed.
The functions png_read_init(info_ptr), png_write_init(info_ptr),
png_info_init(info_ptr), png_read_destroy(), and png_write_destroy()
have been removed. They have been deprecated since libpng-0.95.
The png_permit_empty_plte() was removed. It has been deprecated
since libpng-1.0.9. Use png_permit_mng_features() instead.
We removed the obsolete stub functions png_get_mmx_flagmask(),
png_set_mmx_thresholds(), png_get_asm_flags(),
png_get_mmx_bitdepth_threshold(), png_get_mmx_rowbytes_threshold(),
png_set_asm_flags(), and png_mmx_supported()
We removed the obsolete png_check_sig(), png_memcpy_check(), and
png_memset_check() functions. Instead use !png_sig_cmp(), memcpy(),
and memset(), respectively.
The function png_set_gray_1_2_4_to_8() was removed. It has been
deprecated since libpng-1.0.18 and 1.2.9, when it was replaced with
png_set_expand_gray_1_2_4_to_8() because the former function also
expanded any tRNS chunk to an alpha channel.
Macros for png_get_uint_16, png_get_uint_32, and png_get_int_32
were added and are used by default instead of the corresponding
functions. Unfortunately,
from libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
function) incorrectly returned a value of type png_uint_32.
We changed the prototype for png_malloc() from
png_malloc(png_structp png_ptr, png_uint_32 size)
to
png_malloc(png_structp png_ptr, png_alloc_size_t size)
This also applies to the prototype for the user replacement malloc_fn().
The png_calloc() function was added and is used in place of
of "png_malloc(); memset();" except in the case in png_read_png()
where the array consists of pointers; in this case a "for" loop is used
after the png_malloc() to set the pointers to NULL, to give robust.
behavior in case the application runs out of memory part-way through
the process.
We changed the prototypes of png_get_compression_buffer_size() and
png_set_compression_buffer_size() to work with png_size_t instead of
png_uint_32.
Support for numbered error messages was removed by default, since we
never got around to actually numbering the error messages. The function
png_set_strip_error_numbers() was removed from the library by default.
The png_zalloc() and png_zfree() functions are no longer exported.
The png_zalloc() function no longer zeroes out the memory that it
allocates. Applications that called png_zalloc(png_ptr, number, size)
can call png_calloc(png_ptr, number*size) instead, and can call
png_free() instead of png_zfree().
Support for dithering was disabled by default in libpng-1.4.0, because
it has not been well tested and doesn't actually "dither".
The code was not
removed, however, and could be enabled by building libpng with
PNG_READ_DITHER_SUPPORTED defined. In libpng-1.4.2, this support
was re-enabled, but the function was renamed png_set_quantize() to
reflect more accurately what it actually does. At the same time,
the PNG_DITHER_[RED,GREEN_BLUE]_BITS macros were also renamed to
PNG_QUANTIZE_[RED,GREEN,BLUE]_BITS, and PNG_READ_DITHER_SUPPORTED
was renamed to PNG_READ_QUANTIZE_SUPPORTED.
We removed the trailing '.' from the warning and error messages.
XI. Changes to Libpng from version 1.4.x to 1.5.x
From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
function) incorrectly returned a value of type png_uint_32.
The incorrect macro was removed from libpng-1.4.5.
Checking for invalid palette index on write was added at libpng
1.5.10. If a pixel contains an invalid (out-of-range) index libpng issues
a benign error. This is enabled by default because this condition is an
error according to the PNG specification, Clause 11.3.2, but the error can
be ignored in each png_ptr with
png_set_check_for_invalid_index(png_ptr, allowed);
allowed - one of
0: disable benign error (accept the
invalid data without warning).
1: enable benign error (treat the
invalid data as an error or a
warning).
If the error is ignored, or if png_benign_error() treats it as a warning,
any invalid pixels are decoded as opaque black by the decoder and written
as-is by the encoder.
Retrieving the maximum palette index found was added at libpng-1.5.15.
This statement must appear after png_read_png() or png_read_image() while
reading, and after png_write_png() or png_write_image() while writing.
int max_palette = png_get_palette_max(png_ptr, info_ptr);
This will return the maximum palette index found in the image, or "-1" if
the palette was not checked, or "0" if no palette was found. Note that this
does not account for any palette index used by ancillary chunks such as the
bKGD chunk; you must check those separately to determine the maximum
palette index actually used.
There are no substantial API changes between the non-deprecated parts of
the 1.4.5 API and the 1.5.0 API; however, the ability to directly access
members of the main libpng control structures, png_struct and png_info,
deprecated in earlier versions of libpng, has been completely removed from
libpng 1.5.
We no longer include zlib.h in png.h. The include statement has been moved
to pngstruct.h, where it is not accessible by applications. Applications that
need access to information in zlib.h will need to add the '#include "zlib.h"'
directive. It does not matter whether this is placed prior to or after
the '"#include png.h"' directive.
The png_sprintf(), png_strcpy(), and png_strncpy() macros are no longer used
and were removed.
We moved the png_strlen(), png_memcpy(), png_memset(), and png_memcmp()
macros into a private header file (pngpriv.h) that is not accessible to
applications.
In png_get_iCCP, the type of "profile" was changed from png_charpp
to png_bytepp, and in png_set_iCCP, from png_charp to png_const_bytep.
There are changes of form in png.h, including new and changed macros to
declare parts of the API. Some API functions with arguments that are
pointers to data not modified within the function have been corrected to
declare these arguments with PNG_CONST.
Much of the internal use of C macros to control the library build has also
changed and some of this is visible in the exported header files, in
particular the use of macros to control data and API elements visible
during application compilation may require significant revision to
application code. (It is extremely rare for an application to do this.)
Any program that compiled against libpng 1.4 and did not use deprecated
features or access internal library structures should compile and work
against libpng 1.5, except for the change in the prototype for
png_get_iCCP() and png_set_iCCP() API functions mentioned above.
libpng 1.5.0 adds PNG_ PASS macros to help in the reading and writing of
interlaced images. The macros return the number of rows and columns in
each pass and information that can be used to de-interlace and (if
absolutely necessary) interlace an image.
libpng 1.5.0 adds an API png_longjmp(png_ptr, value). This API calls
the application-provided png_longjmp_ptr on the internal, but application
initialized, longjmp buffer. It is provided as a convenience to avoid
the need to use the png_jmpbuf macro, which had the unnecessary side
effect of resetting the internal png_longjmp_ptr value.
libpng 1.5.0 includes a complete fixed point API. By default this is
present along with the corresponding floating point API. In general the
fixed point API is faster and smaller than the floating point one because
the PNG file format used fixed point, not floating point. This applies
even if the library uses floating point in internal calculations. A new
macro, PNG_FLOATING_ARITHMETIC_SUPPORTED, reveals whether the library
uses floating point arithmetic (the default) or fixed point arithmetic
internally for performance critical calculations such as gamma correction.
In some cases, the gamma calculations may produce slightly different
results. This has changed the results in png_rgb_to_gray and in alpha
composition (png_set_background for example). This applies even if the
original image was already linear (gamma == 1.0) and, therefore, it is
not necessary to linearize the image. This is because libpng has *not*
been changed to optimize that case correctly, yet.
Fixed point support for the sCAL chunk comes with an important caveat;
the sCAL specification uses a decimal encoding of floating point values
and the accuracy of PNG fixed point values is insufficient for
representation of these values. Consequently a "string" API
(png_get_sCAL_s and png_set_sCAL_s) is the only reliable way of reading
arbitrary sCAL chunks in the absence of either the floating point API or
internal floating point calculations. Starting with libpng-1.5.0, both
of these functions are present when PNG_sCAL_SUPPORTED is defined. Prior
to libpng-1.5.0, their presence also depended upon PNG_FIXED_POINT_SUPPORTED
being defined and PNG_FLOATING_POINT_SUPPORTED not being defined.
Applications no longer need to include the optional distribution header
file pngusr.h or define the corresponding macros during application
build in order to see the correct variant of the libpng API. From 1.5.0
application code can check for the corresponding _SUPPORTED macro:
#ifdef PNG_INCH_CONVERSIONS_SUPPORTED
/* code that uses the inch conversion APIs. */
#endif
This macro will only be defined if the inch conversion functions have been
compiled into libpng. The full set of macros, and whether or not support
has been compiled in, are available in the header file pnglibconf.h.
This header file is specific to the libpng build. Notice that prior to
1.5.0 the _SUPPORTED macros would always have the default definition unless
reset by pngusr.h or by explicit settings on the compiler command line.
These settings may produce compiler warnings or errors in 1.5.0 because
of macro redefinition.
Applications can now choose whether to use these macros or to call the
corresponding function by defining PNG_USE_READ_MACROS or
PNG_NO_USE_READ_MACROS before including png.h. Notice that this is
only supported from 1.5.0; defining PNG_NO_USE_READ_MACROS prior to 1.5.0
will lead to a link failure.
Prior to libpng-1.5.4, the zlib compressor used the same set of parameters
when compressing the IDAT data and textual data such as zTXt and iCCP.
In libpng-1.5.4 we reinitialized the zlib stream for each type of data.
We added five png_set_text_*() functions for setting the parameters to
use with textual data.
Prior to libpng-1.5.4, the PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
option was off by default, and slightly inaccurate scaling occurred.
This option can no longer be turned off, and the choice of accurate
or inaccurate 16-to-8 scaling is by using the new png_set_scale_16_to_8()
API for accurate scaling or the old png_set_strip_16_to_8() API for simple
chopping. In libpng-1.5.4, the PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
macro became PNG_READ_SCALE_16_TO_8_SUPPORTED, and the PNG_READ_16_TO_8
macro became PNG_READ_STRIP_16_TO_8_SUPPORTED, to enable the two
png_set_*_16_to_8() functions separately.
Prior to libpng-1.5.4, the png_set_user_limits() function could only be
used to reduce the width and height limits from the value of
PNG_USER_WIDTH_MAX and PNG_USER_HEIGHT_MAX, although this document said
that it could be used to override them. Now this function will reduce or
increase the limits.
Starting in libpng-1.5.10, the user limits can be set en masse with the
configuration option PNG_SAFE_LIMITS_SUPPORTED. If this option is enabled,
a set of "safe" limits is applied in pngpriv.h. These can be overridden by
application calls to png_set_user_limits(), png_set_user_chunk_cache_max(),
and/or png_set_user_malloc_max() that increase or decrease the limits. Also,
in libpng-1.5.10 the default width and height limits were increased
from 1,000,000 to 0x7ffffff (i.e., made unlimited). Therefore, the
limits are now
default safe
png_user_width_max 0x7fffffff 1,000,000
png_user_height_max 0x7fffffff 1,000,000
png_user_chunk_cache_max 0 (unlimited) 128
png_user_chunk_malloc_max 0 (unlimited) 8,000,000
The png_set_option() function (and the "options" member of the png struct) was
added to libpng-1.5.15.
The library now supports a complete fixed point implementation and can
thus be used on systems that have no floating point support or very
limited or slow support. Previously gamma correction, an essential part
of complete PNG support, required reasonably fast floating point.
As part of this the choice of internal implementation has been made
independent of the choice of fixed versus floating point APIs and all the
missing fixed point APIs have been implemented.
The exact mechanism used to control attributes of API functions has
changed, as described in the INSTALL file.
A new test program, pngvalid, is provided in addition to pngtest.
pngvalid validates the arithmetic accuracy of the gamma correction
calculations and includes a number of validations of the file format.
A subset of the full range of tests is run when "make check" is done
(in the 'configure' build.) pngvalid also allows total allocated memory
usage to be evaluated and performs additional memory overwrite validation.
Many changes to individual feature macros have been made. The following
are the changes most likely to be noticed by library builders who
configure libpng:
1) All feature macros now have consistent naming:
#define PNG_NO_feature turns the feature off
#define PNG_feature_SUPPORTED turns the feature on
pnglibconf.h contains one line for each feature macro which is either:
#define PNG_feature_SUPPORTED
if the feature is supported or:
/*#undef PNG_feature_SUPPORTED*/
if it is not. Library code consistently checks for the 'SUPPORTED' macro.
It does not, and libpng applications should not, check for the 'NO' macro
which will not normally be defined even if the feature is not supported.
The 'NO' macros are only used internally for setting or not setting the
corresponding 'SUPPORTED' macros.
Compatibility with the old names is provided as follows:
PNG_INCH_CONVERSIONS turns on PNG_INCH_CONVERSIONS_SUPPORTED
And the following definitions disable the corresponding feature:
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
PNG_FLOATING_ARITHMETIC_SUPPORTED chooses between the internal floating
point implementation or the fixed point one. Typically the fixed point
implementation is larger and slower than the floating point implementation
on a system that supports floating point; however, it may be faster on a
system which lacks floating point hardware and therefore uses a software
emulation.
4) Added PNG_{READ,WRITE}_INT_FUNCTIONS_SUPPORTED. This allows the
functions to read and write ints to be disabled independently of
PNG_USE_READ_MACROS, which allows libpng to be built with the functions
even though the default is to use the macros - this allows applications
to choose at app buildtime whether or not to use macros (previously
impossible because the functions weren't in the default build.)
XII. Changes to Libpng from version 1.5.x to 1.6.x
A "simplified API" has been added (see documentation in png.h and a simple
example in contrib/examples/pngtopng.c). The new publicly visible API
includes the following:
macros:
PNG_FORMAT_*
PNG_IMAGE_*
structures:
png_control
png_image
read functions
png_image_begin_read_from_file()
png_image_begin_read_from_stdio()
png_image_begin_read_from_memory()
png_image_finish_read()
png_image_free()
write functions
png_image_write_to_file()
png_image_write_to_stdio()
Starting with libpng-1.6.0, you can configure libpng to prefix all exported
symbols, using the PNG_PREFIX macro.
We no longer include string.h in png.h. The include statement has been moved
to pngpriv.h, where it is not accessible by applications. Applications that
need access to information in string.h must add an '#include <string.h>'
directive. It does not matter whether this is placed prior to or after
the '#include "png.h"' directive.
The following API are now DEPRECATED:
png_info_init_3()
png_convert_to_rfc1123() which has been replaced
with png_convert_to_rfc1123_buffer()
png_malloc_default()
png_free_default()
png_reset_zstream()
The following have been removed:
png_get_io_chunk_name(), which has been replaced
with png_get_io_chunk_type(). The new
function returns a 32-bit integer instead of
a string.
The png_sizeof(), png_strlen(), png_memcpy(), png_memcmp(), and
png_memset() macros are no longer used in the libpng sources and
have been removed. These had already been made invisible to applications
(i.e., defined in the private pngpriv.h header file) since libpng-1.5.0.
The signatures of many exported functions were changed, such that
png_structp became png_structrp or png_const_structrp
png_infop became png_inforp or png_const_inforp
where "rp" indicates a "restricted pointer".
Error detection in some chunks has improved; in particular the iCCP chunk
reader now does pretty complete validation of the basic format. Some bad
profiles that were previously accepted are now accepted with a warning or
rejected, depending upon the png_set_benign_errors() setting, in particular
the very old broken Microsoft/HP 3144-byte sRGB profile. Starting with
libpng-1.6.11, recognizing and checking sRGB profiles can be avoided by
means of
#if defined(PNG_SKIP_sRGB_CHECK_PROFILE) && \
defined(PNG_SET_OPTION_SUPPORTED)
png_set_option(png_ptr, PNG_SKIP_sRGB_CHECK_PROFILE,
PNG_OPTION_ON);
#endif
It's not a good idea to do this if you are using the new "simplified API",
which needs to be able to recognize sRGB profiles conveyed via the iCCP
chunk.
The PNG spec requirement that only grayscale profiles may appear in images
with color type 0 or 4 and that even if the image only contains gray pixels,
only RGB profiles may appear in images with color type 2, 3, or 6, is now
enforced. The sRGB chunk is allowed to appear in images with any color type
and is interpreted by libpng to convey a one-tracer-curve gray profile or a
three-tracer-curve RGB profile as appropriate.
Prior to libpng-1.6.0 a warning would be issued if the iTXt chunk contained
an empty language field or an empty translated keyword. Both of these
are allowed by the PNG specification, so these warnings are no longer issued.
The library now issues an error if the application attempts to set a
transform after it calls png_read_update_info() or if it attempts to call
both png_read_update_info() and png_start_read_image() or to call either
of them more than once.
The default condition for benign_errors is now to treat benign errors as
warnings while reading and as errors while writing.
The library now issues a warning if both background processing and RGB to
gray are used when gamma correction happens. As with previous versions of
the library the results are numerically very incorrect in this case.
There are some minor arithmetic changes in some transforms such as
png_set_background(), that might be detected by certain regression tests.
Unknown chunk handling has been improved internally, without any API change.
This adds more correct option control of the unknown handling, corrects
a pre-existing bug where the per-chunk 'keep' setting is ignored, and makes
it possible to skip IDAT chunks in the sequential reader.
The machine-generated configure files are no longer included in branches
libpng16 and later of the GIT repository. They continue to be included
in the tarball releases, however.
Libpng-1.6.0 through 1.6.2 used the CMF bytes at the beginning of the IDAT
stream to set the size of the sliding window for reading instead of using the
default 32-kbyte sliding window size. It was discovered that there are
hundreds of PNG files in the wild that have incorrect CMF bytes that caused
zlib to issue the "invalid distance too far back" error and reject the file.
Libpng-1.6.3 and later calculate their own safe CMF from the image dimensions,
provide a way to revert to the libpng-1.5.x behavior (ignoring the CMF bytes
and using a 32-kbyte sliding window), by using
png_set_option(png_ptr, PNG_MAXIMUM_INFLATE_WINDOW,
PNG_OPTION_ON);
and provide a tool (contrib/tools/pngfix) for rewriting a PNG file while
optimizing the CMF bytes in its IDAT chunk correctly.
Libpng-1.6.0 and libpng-1.6.1 wrote uncompressed iTXt chunks with the wrong
length, which resulted in PNG files that cannot be read beyond the bad iTXt
chunk. This error was fixed in libpng-1.6.3, and a tool (called
contrib/tools/png-fix-itxt) has been added to the libpng distribution.
XIII. Detecting libpng
The png_get_io_ptr() function has been present since libpng-0.88, has never
changed, and is unaffected by conditional compilation macros. It is the
best choice for use in configure scripts for detecting the presence of any
libpng version since 0.88. In an autoconf "configure.in" you could use
AC_CHECK_LIB(png, png_get_io_ptr, ...
XV. Source code repository
Since about February 2009, version 1.2.34, libpng has been under "git" source
control. The git repository was built from old libpng-x.y.z.tar.gz files
going back to version 0.70. You can access the git repository (read only)
at
git://git.code.sf.net/p/libpng/code
or you can browse it with a web browser by selecting the "code" button at
https://sourceforge.net/projects/libpng
Patches can be sent to glennrp at users.sourceforge.net or to
png-mng-implement at lists.sourceforge.net or you can upload them to
the libpng bug tracker at
http://libpng.sourceforge.net
We also accept patches built from the tar or zip distributions, and
simple verbal discriptions of bug fixes, reported either to the
SourceForge bug tracker, to the png-mng-implement at lists.sf.net
mailing list, or directly to glennrp.
XV. Coding style
Our coding style is similar to the "Allman" style
(See http://en.wikipedia.org/wiki/Indent_style#Allman_style), with curly
braces on separate lines:
if (condition)
{
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
used them in the past in some now-abandoned MMX assembler
code.
Functions and their curly braces are not indented, and
exported functions are marked with PNGAPI:
/* This is a public function that is visible to
* application programmers. It does thus-and-so.
*/
void PNGAPI
png_exported_function(png_ptr, png_info, foo)
{
body;
}
The return type and decorations are placed on a separate line
ahead of the function name, as illustrated above.
The prototypes for all exported functions appear in png.h,
above the comment that says
/* Maintainer: Put new public prototypes here ... */
We mark all non-exported functions with "/* PRIVATE */"":
void /* PRIVATE */
png_non_exported_function(png_ptr, png_info, foo)
{
body;
}
The prototypes for non-exported functions (except for those in
pngtest) appear in pngpriv.h above the comment that says
/* Maintainer: Put new private prototypes here ^ */
To avoid polluting the global namespace, the names of all exported
functions and variables begin with "png_", and all publicly visible C
preprocessor macros begin with "PNG". We request that applications that
use libpng *not* begin any of their own symbols with either of these strings.
We put a space after the "sizeof" operator and we omit the
optional parentheses around its argument when the argument
is an expression, not a type name, and we always enclose the
sizeof operator, with its argument, in parentheses:
(sizeof (png_uint_32))
(sizeof array)
Prior to libpng-1.6.0 we used a "png_sizeof()" macro, formatted as
though it were a function.
Control keywords if, for, while, and switch are always followed by a space
to distinguish them from function calls, which have no trailing space.
We put a space after each comma and after each semicolon
in "for" statements, and we put spaces before and after each
C binary operator and after "for" or "while", and before
"?". We don't put a space between a typecast and the expression
being cast, nor do we put one between a function name and the
src/Source/LibPNG/libpng-manual.txt view on Meta::CPAN
We prefer to use underscores in variable names rather than camelCase, except
for a few type names that we inherit from zlib.h.
We prefer "if (something != 0)" and "if (something == 0)"
over "if (something)" and if "(!something)", respectively.
We do not use the TAB character for indentation in the C sources.
Lines do not exceed 80 characters.
Other rules can be inferred by inspecting the libpng source.
XVI. Y2K Compliance in libpng
December 22, 2014
Since the PNG Development group is an ad-hoc body, we can't make
an official declaration.
This is your unofficial assurance that libpng from version 0.71 and
upward through 1.6.16 are Y2K compliant. It is my belief that earlier
versions were also Y2K compliant.
Libpng only has two year fields. One is a 2-byte unsigned integer
that will hold years up to 65535. The other, which is deprecated,
holds the date in text format, and will hold years up to 9999.
The integer is
"png_uint_16 year" in png_time_struct.
The string is
"char time_buffer[29]" in png_struct. This is no longer used
in libpng-1.6.x and will be removed from libpng-1.7.0.
There are seven time-related functions:
png_convert_to_rfc_1123_buffer() in png.c
(formerly png_convert_to_rfc_1152() in error, and
also formerly png_convert_to_rfc_1123())
png_convert_from_struct_tm() in pngwrite.c, called
in pngwrite.c
png_convert_from_time_t() in pngwrite.c
png_get_tIME() in pngget.c
png_handle_tIME() in pngrutil.c, called in pngread.c
png_set_tIME() in pngset.c
png_write_tIME() in pngwutil.c, called in pngwrite.c
All appear to handle dates properly in a Y2K environment. The
png_convert_from_time_t() function calls gmtime() to convert from system
clock time, which returns (year - 1900), which we properly convert to
the full 4-digit year. There is a possibility that applications using
libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
function, or that they are incorrectly passing only a 2-digit year
instead of "year - 1900" into the png_convert_from_struct_tm() function,
but this is not under our control. The libpng documentation has always
stated that it works with 4-digit years, and the APIs have been
documented as such.
The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned
integer to hold the year, and can hold years as large as 65535.
zlib, upon which libpng depends, is also Y2K compliant. It contains
no date-related code.
Glenn Randers-Pehrson
libpng maintainer
PNG Development Group
src/Source/LibPNG/libpng.3 view on Meta::CPAN
.TH LIBPNG 3 "December 22, 2014"
.SH NAME
libpng \- Portable Network Graphics (PNG) Reference Library 1.6.16
.SH SYNOPSIS
\fB
#include <png.h>\fP
\fBpng_uint_32 png_access_version_number \fI(void\fP\fB);\fP
\fBvoid png_benign_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
\fBvoid png_build_grayscale_palette (int \fP\fIbit_depth\fP\fB, png_colorp \fIpalette\fP\fB);\fP
\fBpng_voidp png_calloc (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
\fBvoid png_chunk_benign_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
\fBvoid png_chunk_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
\fBvoid png_chunk_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP
\fBvoid png_convert_from_struct_tm (png_timep \fP\fIptime\fP\fB, struct tm FAR * \fIttime\fP\fB);\fP
\fBvoid png_convert_from_time_t (png_timep \fP\fIptime\fP\fB, time_t \fIttime\fP\fB);\fP
\fBpng_charp png_convert_to_rfc1123 (png_structp \fP\fIpng_ptr\fP\fB, png_timep \fIptime\fP\fB);\fP
\fBpng_infop png_create_info_struct (png_structp \fIpng_ptr\fP\fB);\fP
\fBpng_structp png_create_read_struct (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarn_fn\fP\fB);\fP
\fBpng_structp png_create_read_struct_2 (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\f...
\fBpng_structp png_create_write_struct (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarn_fn\fP\fB);\fP
\fBpng_structp png_create_write_struct_2 (png_const_charp \fP\fIuser_png_ver\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fP\fIwarn_fn\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\...
\fBvoid png_data_freer (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIfreer\fP\fB, png_uint_32 \fImask)\fP\fB);\fP
\fBvoid png_destroy_info_struct (png_structp \fP\fIpng_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP
\fBvoid png_destroy_read_struct (png_structpp \fP\fIpng_ptr_ptr\fP\fB, png_infopp \fP\fIinfo_ptr_ptr\fP\fB, png_infopp \fIend_info_ptr_ptr\fP\fB);\fP
\fBvoid png_destroy_write_struct (png_structpp \fP\fIpng_ptr_ptr\fP\fB, png_infopp \fIinfo_ptr_ptr\fP\fB);\fP
\fBvoid png_err (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_error (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fIerror\fP\fB);\fP
\fBvoid png_free (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP
\fBvoid png_free_chunk_list (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_free_default (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fIptr\fP\fB);\fP
\fBvoid png_free_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fInum\fP\fB);\fP
\fBpng_byte png_get_bit_depth (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_bKGD (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fI*background\fP\fB);\fP
\fBpng_byte png_get_channels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_cHRM (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fP\fI*white_x\fP\fB, double \fP\fI*white_y\fP\fB, double \fP\fI*red_x\fP\fB, double \fP\fI*red_y\fP\fB, double \fP\fI*green_x\fP\fB, dou...
\fBpng_uint_32 png_get_cHRM_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*white_x\fP\fB, png_uint_32 \fP\fI*white_y\fP\fB, png_uint_32 \fP\fI*red_x\fP\fB, png_uint_32 \fP\fI*red_y\fP\fB, png_ui...
\fBpng_uint_32 png_get_cHRM_XYZ (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fP\fI*red_X\fP\fB, double \fP\fI*red_Y\fP\fB, double \fP\fI*red_Z\fP\fB, double \fP\fI*green_X\fP\fB, double \fP\fI*green_Y\fP\fB, double ...
\fBpng_uint_32 png_get_cHRM_XYZ_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_fixed_point \fP\fI*int_red_X\fP\fB, png_fixed_point \fP\fI*int_red_Y\fP\fB, png_fixed_point \fP\fI*int_red_Z\fP\fB, png_fixed_point \fP\...
\fBpng_uint_32 png_get_chunk_cache_max (png_const_structp \fIpng_ptr\fP\fB);\fP
\fBpng_alloc_size_t png_get_chunk_malloc_max (png_const_structp \fIpng_ptr\fP\fB);\fP
\fBpng_byte png_get_color_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_compression_buffer_size (png_const_structp \fIpng_ptr\fP\fB);\fP
\fBpng_byte png_get_compression_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_byte png_get_copyright (png_const_structp \fIpng_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_current_row_number \fI(png_const_structp\fP\fB);\fP
\fBpng_byte png_get_current_pass_number \fI(png_const_structp\fP\fB);\fP
\fBpng_voidp png_get_error_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
\fBpng_byte png_get_filter_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_gAMA (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, double \fI*file_gamma\fP\fB);\fP
\fBpng_uint_32 png_get_gAMA_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fI*int_file_gamma\fP\fB);\fP
\fBpng_byte png_get_header_ver (png_const_structp \fIpng_ptr\fP\fB);\fP
\fBpng_byte png_get_header_version (png_const_structp \fIpng_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_hIST (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fI*hist\fP\fB);\fP
\fBpng_uint_32 png_get_iCCP (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_charpp \fP\fIname\fP\fB, int \fP\fI*compression_type\fP\fB, png_bytepp \fP\fIprofile\fP\fB, png_uint_32 \fI*proflen\fP\fB);\fP
\fBpng_uint_32 png_get_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*width\fP\fB, png_uint_32 \fP\fI*height\fP\fB, int \fP\fI*bit_depth\fP\fB, int \fP\fI*color_type\fP\fB, int \fP\fI*interlace_type\fP\fB, i...
\fBpng_uint_32 png_get_image_height (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_image_width (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_int_32 png_get_int_32 (png_bytep \fIbuf\fP\fB);\fP
\fBpng_byte png_get_interlace_type (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_io_chunk_type (png_const_structp \fIpng_ptr\fP\fB);\fP
\fBpng_voidp png_get_io_ptr (png_structp \fIpng_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_io_state (png_structp \fIpng_ptr\fP\fB);\fP
\fBpng_byte png_get_libpng_ver (png_const_structp \fIpng_ptr\fP\fB);\fP
\fBpng_voidp png_get_mem_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_oFFs (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*offset_x\fP\fB, png_uint_32 \fP\fI*offset_y\fP\fB, int \fI*unit_type\fP\fB);\fP
\fBpng_uint_32 png_get_pCAL (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fI*purpose\fP\fB, png_int_32 \fP\fI*X0\fP\fB, png_int_32 \fP\fI*X1\fP\fB, int \fP\fI*type\fP\fB, int \fP\fI*nparams\fP\fB, png_cha...
\fBpng_uint_32 png_get_pHYs (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*res_x\fP\fB, png_uint_32 \fP\fI*res_y\fP\fB, int \fI*unit_type\fP\fB);\fP
\fBfloat png_get_pixel_aspect_ratio (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_pHYs_dpi (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*res_x\fP\fB, png_uint_32 \fP\fI*res_y\fP\fB, int \fI*unit_type\fP\fB);\fP
\fBpng_fixed_point png_get_pixel_aspect_ratio_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_voidp png_get_progressive_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_PLTE (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fI*palette\fP\fB, int \fI*num_palette\fP\fB);\fP
\fBpng_byte png_get_rgb_to_gray_status (png_const_structp \fIpng_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_rowbytes (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_bytepp png_get_rows (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_sBIT (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fI*sig_bit\fP\fB);\fP
\fBvoid png_get_sCAL (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, double* \fP\fIwidth\fP\fB, double* \fIheight\fP\fB);\fP
\fBvoid png_get_sCAL_fixed (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, png_fixed_pointp \fP\fIwidth\fP\fB, png_fixed_pointp \fIheight\fP\fB);\fP
\fBvoid png_get_sCAL_s (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, png_charpp \fP\fIwidth\fP\fB, png_charpp \fIheight\fP\fB);\fP
\fBpng_bytep png_get_signature (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_sPLT (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_spalette_p \fI*splt_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_sRGB (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, int \fI*file_srgb_intent\fP\fB);\fP
\fBpng_uint_32 png_get_text (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fI*text_ptr\fP\fB, int \fI*num_text\fP\fB);\fP
\fBpng_uint_32 png_get_tIME (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fI*mod_time\fP\fB);\fP
\fBpng_uint_32 png_get_tRNS (png_const_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fI*trans_alpha\fP\fB, int \fP\fI*num_trans\fP\fB, png_color_16p \fI*trans_color\fP\fB);\fP
\fB/* This function is really an inline macro. \fI*/
\fBpng_uint_16 png_get_uint_16 (png_bytep \fIbuf\fP\fB);\fP
\fBpng_uint_32 png_get_uint_31 (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIbuf\fP\fB);\fP
\fB/* This function is really an inline macro. \fI*/
\fBpng_uint_32 png_get_uint_32 (png_bytep \fIbuf\fP\fB);\fP
\fBpng_uint_32 png_get_unknown_chunks (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkpp \fIunknowns\fP\fB);\fP
\fBpng_voidp png_get_user_chunk_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_user_height_max (png_const_structp \fIpng_ptr\fP\fB);\fP
\fBpng_voidp png_get_user_transform_ptr (png_const_structp \fIpng_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_user_width_max (png_const_structp \fIpng_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_valid (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIflag\fP\fB);\fP
\fBfloat png_get_x_offset_inches (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_fixed_point png_get_x_offset_inches_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_int_32 png_get_x_offset_microns (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_int_32 png_get_x_offset_pixels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_x_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_x_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBfloat png_get_y_offset_inches (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_fixed_point png_get_y_offset_inches_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_int_32 png_get_y_offset_microns (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_int_32 png_get_y_offset_pixels (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_y_pixels_per_inch (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBpng_uint_32 png_get_y_pixels_per_meter (png_const_structp \fP\fIpng_ptr\fP\fB, png_const_infop \fIinfo_ptr\fP\fB);\fP
\fBint png_handle_as_unknown (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIchunk_name\fP\fB);\fP
\fBint png_image_begin_read_from_file (png_imagep \fP\fIimage\fP\fB, const char \fI*file_name\fP\fB);\fP
\fBint png_image_begin_read_from_stdio (png_imagep \fP\fIimage\fP\fB, FILE* \fIfile\fP\fB);\fP
\fBint, png_image_begin_read_from_memory (png_imagep \fP\fIimage\fP\fB, png_const_voidp \fP\fImemory\fP\fB, png_size_t \fIsize\fP\fB);\fP
\fBint png_image_finish_read (png_imagep \fP\fIimage\fP\fB, png_colorp \fP\fIbackground\fP\fB, void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap\fP\fB);\fP
\fBvoid png_image_free (png_imagep \fIimage\fP\fB);\fP
\fBint png_image_write_to_file (png_imagep \fP\fIimage\fP\fB, const char \fP\fI*file\fP\fB, int \fP\fIconvert_to_8bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap\fP\fB);\fP
\fBint png_image_write_to_stdio (png_imagep \fP\fIimage\fP\fB, FILE \fP\fI*file\fP\fB, int \fP\fIconvert_to_8_bit\fP\fB, const void \fP\fI*buffer\fP\fB, png_int_32 \fP\fIrow_stride\fP\fB, void \fI*colormap)\fP\fB);\fP
\fBvoid png_info_init_3 (png_infopp \fP\fIinfo_ptr\fP\fB, png_size_t \fIpng_info_struct_size\fP\fB);\fP
\fBvoid png_init_io (png_structp \fP\fIpng_ptr\fP\fB, FILE \fI*fp\fP\fB);\fP
\fBvoid png_longjmp (png_structp \fP\fIpng_ptr\fP\fB, int \fIval\fP\fB);\fP
\fBpng_voidp png_malloc (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
\fBpng_voidp png_malloc_default (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
\fBpng_voidp png_malloc_warn (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIsize\fP\fB);\fP
\fBpng_uint_32 png_permit_mng_features (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fImng_features_permitted\fP\fB);\fP
\fBvoid png_process_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fIbuffer\fP\fB, png_size_t \fIbuffer_size\fP\fB);\fP
\fBpng_size_t png_process_data_pause \fP\fI(png_structp\fP\fB, int \fIsave\fP\fB);\fP
\fBpng_uint_32 png_process_data_skip \fI(png_structp\fP\fB);\fP
\fBvoid png_progressive_combine_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIold_row\fP\fB, png_bytep \fInew_row\fP\fB);\fP
\fBvoid png_read_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fBvoid png_read_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP
\fBvoid png_read_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fBvoid png_read_png (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fItransforms\fP\fB, png_voidp \fIparams\fP\fB);\fP
\fBvoid png_read_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIrow\fP\fB, png_bytep \fIdisplay_row\fP\fB);\fP
\fBvoid png_read_rows (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fP\fIrow\fP\fB, png_bytepp \fP\fIdisplay_row\fP\fB, png_uint_32 \fInum_rows\fP\fB);\fP
\fBvoid png_read_update_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fBint png_reset_zstream (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_save_int_32 (png_bytep \fP\fIbuf\fP\fB, png_int_32 \fIi\fP\fB);\fP
\fBvoid png_save_uint_16 (png_bytep \fP\fIbuf\fP\fB, unsigned int \fIi\fP\fB);\fP
\fBvoid png_save_uint_32 (png_bytep \fP\fIbuf\fP\fB, png_uint_32 \fIi\fP\fB);\fP
\fBvoid png_set_add_alpha (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP
\fBvoid png_set_alpha_mode (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImode\fP\fB, double \fIoutput_gamma\fP\fB);\fP
\fBvoid png_set_alpha_mode_fixed (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImode\fP\fB, png_fixed_point \fIoutput_gamma\fP\fB);\fP
\fBvoid png_set_background (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, double \fIbackground_gamma\fP\fB);\fP
\fBvoid png_set_background_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, png_uint_32 \fIbackground_gamma\fP\fB);\fP
\fBvoid png_set_benign_errors (png_structp \fP\fIpng_ptr\fP\fB, int \fIallowed\fP\fB);\fP
\fBvoid png_set_bgr (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_bKGD (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_16p \fIbackground\fP\fB);\fP
\fBvoid png_set_check_for_invalid_index(png_structrp \fP\fIpng_ptr\fP\fB, int \fIallowed\fP\fB);\fP
\fBvoid png_set_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fIwhite_x\fP\fB, double \fP\fIwhite_y\fP\fB, double \fP\fIred_x\fP\fB, double \fP\fIred_y\fP\fB, double \fP\fIgreen_x\fP\fB, double \fP\fIgreen_y\fP\fB,...
\fBvoid png_set_cHRM_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwhite_x\fP\fB, png_uint_32 \fP\fIwhite_y\fP\fB, png_uint_32 \fP\fIred_x\fP\fB, png_uint_32 \fP\fIred_y\fP\fB, png_uint_32 \fP\fIgreen_x\fP\...
\fBvoid png_set_cHRM_XYZ (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fP\fIred_X\fP\fB, double \fP\fIred_Y\fP\fB, double \fP\fIred_Z\fP\fB, double \fP\fIgreen_X\fP\fB, double \fP\fIgreen_Y\fP\fB, double \fP\fIgreen_Z\fP\f...
\fBvoid png_set_cHRM_XYZ_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_fixed_point \fP\fIint_red_X\fP\fB, png_fixed_point \fP\fIint_red_Y\fP\fB, png_fixed_point \fP\fIint_red_Z\fP\fB, png_fixed_point \fP\fIint_green_X\fP...
\fBvoid png_set_chunk_cache_max (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIuser_chunk_cache_max\fP\fB);\fP
\fBvoid png_set_compression_level (png_structp \fP\fIpng_ptr\fP\fB, int \fIlevel\fP\fB);\fP
\fBvoid png_set_compression_mem_level (png_structp \fP\fIpng_ptr\fP\fB, int \fImem_level\fP\fB);\fP
\fBvoid png_set_compression_method (png_structp \fP\fIpng_ptr\fP\fB, int \fImethod\fP\fB);\fP
\fBvoid png_set_compression_strategy (png_structp \fP\fIpng_ptr\fP\fB, int \fIstrategy\fP\fB);\fP
\fBvoid png_set_compression_window_bits (png_structp \fP\fIpng_ptr\fP\fB, int \fIwindow_bits\fP\fB);\fP
\fBvoid png_set_crc_action (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIcrit_action\fP\fB, int \fIancil_action\fP\fB);\fP
\fBvoid png_set_error_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIerror_ptr\fP\fB, png_error_ptr \fP\fIerror_fn\fP\fB, png_error_ptr \fIwarning_fn\fP\fB);\fP
\fBvoid png_set_expand (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_expand_16 (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_expand_gray_1_2_4_to_8 (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_filler (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIfiller\fP\fB, int \fIflags\fP\fB);\fP
\fBvoid png_set_filter (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fImethod\fP\fB, int \fIfilters\fP\fB);\fP
\fBvoid png_set_filter_heuristics (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIheuristic_method\fP\fB, int \fP\fInum_weights\fP\fB, png_doublep \fP\fIfilter_weights\fP\fB, png_doublep \fIfilter_costs\fP\fB);\fP
\fBvoid png_set_filter_heuristics_fixed (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIheuristic_method\fP\fB, int \fP\fInum_weights\fP\fB, png_fixed_point_p \fP\fIfilter_weights\fP\fB, png_fixed_point_p \fIfilter_costs\fP\fB);\fP
\fBvoid png_set_flush (png_structp \fP\fIpng_ptr\fP\fB, int \fInrows\fP\fB);\fP
\fBvoid png_set_gamma (png_structp \fP\fIpng_ptr\fP\fB, double \fP\fIscreen_gamma\fP\fB, double \fIdefault_file_gamma\fP\fB);\fP
\fBvoid png_set_gamma_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIscreen_gamma\fP\fB, png_uint_32 \fIdefault_file_gamma\fP\fB);\fP
\fBvoid png_set_gAMA (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fIfile_gamma\fP\fB);\fP
\fBvoid png_set_gAMA_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIfile_gamma\fP\fB);\fP
\fBvoid png_set_gray_1_2_4_to_8 (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_gray_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_hIST (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_16p \fIhist\fP\fB);\fP
\fBvoid png_set_iCCP (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_const_charp \fP\fIname\fP\fB, int \fP\fIcompression_type\fP\fB, png_const_bytep \fP\fIprofile\fP\fB, png_uint_32 \fIproflen\fP\fB);\fP
\fBint png_set_interlace_handling (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_invalid (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fImask\fP\fB);\fP
\fBvoid png_set_invert_alpha (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_invert_mono (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_IHDR (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIwidth\fP\fB, png_uint_32 \fP\fIheight\fP\fB, int \fP\fIbit_depth\fP\fB, int \fP\fIcolor_type\fP\fB, int \fP\fIinterlace_type\fP\fB, int \fP\fIcom...
\fBvoid png_set_keep_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIkeep\fP\fB, png_bytep \fP\fIchunk_list\fP\fB, int \fInum_chunks\fP\fB);\fP
\fBjmp_buf* png_set_longjmp_fn (png_structp \fP\fIpng_ptr\fP\fB, png_longjmp_ptr \fP\fIlongjmp_fn\fP\fB, size_t \fIjmp_buf_size\fP\fB);\fP
\fBvoid png_set_chunk_malloc_max (png_structp \fP\fIpng_ptr\fP\fB, png_alloc_size_t \fIuser_chunk_cache_max\fP\fB);\fP
\fBvoid png_set_compression_buffer_size (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIsize\fP\fB);\fP
\fBvoid png_set_mem_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fImem_ptr\fP\fB, png_malloc_ptr \fP\fImalloc_fn\fP\fB, png_free_ptr \fIfree_fn\fP\fB);\fP
\fBvoid png_set_oFFs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIoffset_x\fP\fB, png_uint_32 \fP\fIoffset_y\fP\fB, int \fIunit_type\fP\fB);\fP
\fBvoid png_set_packing (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_packswap (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_palette_to_rgb (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_pCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fIpurpose\fP\fB, png_int_32 \fP\fIX0\fP\fB, png_int_32 \fP\fIX1\fP\fB, int \fP\fItype\fP\fB, int \fP\fInparams\fP\fB, png_charp \fP\fIunits\fP\fB, pn...
\fBvoid png_set_pHYs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fIres_x\fP\fB, png_uint_32 \fP\fIres_y\fP\fB, int \fIunit_type\fP\fB);\fP
\fBvoid png_set_progressive_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIprogressive_ptr\fP\fB, png_progressive_info_ptr \fP\fIinfo_fn\fP\fB, png_progressive_row_ptr \fP\fIrow_fn\fP\fB, png_progressive_end_ptr \fIend_fn\fP\fB);\fP
\fBvoid png_set_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fInum_palette\fP\fB);\fP
\fBvoid png_set_quantize (png_structp \fP\fIpng_ptr\fP\fB, png_colorp \fP\fIpalette\fP\fB, int \fP\fInum_palette\fP\fB, int \fP\fImaximum_colors\fP\fB, png_uint_16p \fP\fIhistogram\fP\fB, int \fIfull_quantize\fP\fB);\fP
\fBvoid png_set_read_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fIread_data_fn\fP\fB);\fP
\fBvoid png_set_read_status_fn (png_structp \fP\fIpng_ptr\fP\fB, png_read_status_ptr \fIread_row_fn\fP\fB);\fP
\fBvoid png_set_read_user_chunk_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIuser_chunk_ptr\fP\fB, png_user_chunk_ptr \fIread_user_chunk_fn\fP\fB);\fP
\fBvoid png_set_read_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIread_user_transform_fn\fP\fB);\fP
\fBvoid png_set_rgb_to_gray (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIerror_action\fP\fB, double \fP\fIred\fP\fB, double \fIgreen\fP\fB);\fP
\fBvoid png_set_rgb_to_gray_fixed (png_structp \fP\fIpng_ptr\fP\fB, int error_action png_uint_32 \fP\fIred\fP\fB, png_uint_32 \fIgreen\fP\fB);\fP
\fBvoid png_set_rows (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytepp \fIrow_pointers\fP\fB);\fP
\fBvoid png_set_sBIT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_color_8p \fIsig_bit\fP\fB);\fP
\fBvoid png_set_sCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, double \fP\fIwidth\fP\fB, double \fIheight\fP\fB);\fP
\fBvoid png_set_sCAL_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, png_fixed_point \fP\fIwidth\fP\fB, png_fixed_point \fIheight\fP\fB);\fP
\fBvoid png_set_sCAL_s (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, png_charp \fP\fIwidth\fP\fB, png_charp \fIheight\fP\fB);\fP
\fBvoid png_set_scale_16 (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_shift (png_structp \fP\fIpng_ptr\fP\fB, png_color_8p \fItrue_bits\fP\fB);\fP
\fBvoid png_set_sig_bytes (png_structp \fP\fIpng_ptr\fP\fB, int \fInum_bytes\fP\fB);\fP
\fBvoid png_set_sPLT (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_spalette_p \fP\fIsplt_ptr\fP\fB, int \fInum_spalettes\fP\fB);\fP
\fBvoid png_set_sRGB (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIsrgb_intent\fP\fB);\fP
\fBvoid png_set_sRGB_gAMA_and_cHRM (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fIsrgb_intent\fP\fB);\fP
\fBvoid png_set_strip_16 (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_strip_alpha (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_strip_error_numbers (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fIstrip_mode\fP\fB);\fP
\fBvoid png_set_swap (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_swap_alpha (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_set_text (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_textp \fP\fItext_ptr\fP\fB, int \fInum_text\fP\fB);\fP
\fBvoid png_set_text_compression_level (png_structp \fP\fIpng_ptr\fP\fB, int \fIlevel\fP\fB);\fP
\fBvoid png_set_text_compression_mem_level (png_structp \fP\fIpng_ptr\fP\fB, int \fImem_level\fP\fB);\fP
\fBvoid png_set_text_compression_strategy (png_structp \fP\fIpng_ptr\fP\fB, int \fIstrategy\fP\fB);\fP
\fBvoid png_set_text_compression_window_bits (png_structp \fP\fIpng_ptr\fP\fB, int \fIwindow_bits\fP\fB);\fP
\fBvoid \fP\fIpng_set_text_compression_method\fP\fB, (png_structp \fP\fIpng_ptr\fP\fB, int \fImethod)\fP\fB);\fP
\fBvoid png_set_tIME (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_timep \fImod_time\fP\fB);\fP
\fBvoid png_set_tRNS (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fItrans_alpha\fP\fB, int \fP\fInum_trans\fP\fB, png_color_16p \fItrans_color\fP\fB);\fP
\fBvoid png_set_tRNS_to_alpha (png_structp \fIpng_ptr\fP\fB);\fP
\fBpng_uint_32 png_set_unknown_chunks (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_unknown_chunkp \fP\fIunknowns\fP\fB, int \fP\fInum\fP\fB, int \fIlocation\fP\fB);\fP
\fBvoid png_set_unknown_chunk_location (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIchunk\fP\fB, int \fIlocation\fP\fB);\fP
\fBvoid png_set_user_limits (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIuser_width_max\fP\fB, png_uint_32 \fIuser_height_max\fP\fB);\fP
\fBvoid png_set_user_transform_info (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIuser_transform_ptr\fP\fB, int \fP\fIuser_transform_depth\fP\fB, int \fIuser_transform_channels\fP\fB);\fP
\fBvoid png_set_write_fn (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIio_ptr\fP\fB, png_rw_ptr \fP\fIwrite_data_fn\fP\fB, png_flush_ptr \fIoutput_flush_fn\fP\fB);\fP
\fBvoid png_set_write_status_fn (png_structp \fP\fIpng_ptr\fP\fB, png_write_status_ptr \fIwrite_row_fn\fP\fB);\fP
\fBvoid png_set_write_user_transform_fn (png_structp \fP\fIpng_ptr\fP\fB, png_user_transform_ptr \fIwrite_user_transform_fn\fP\fB);\fP
\fBint png_sig_cmp (png_bytep \fP\fIsig\fP\fB, png_size_t \fP\fIstart\fP\fB, png_size_t \fInum_to_check\fP\fB);\fP
\fBvoid png_start_read_image (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_warning (png_structp \fP\fIpng_ptr\fP\fB, png_const_charp \fImessage\fP\fB);\fP
\fBvoid png_write_chunk (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
\fBvoid png_write_chunk_data (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIdata\fP\fB, png_size_t \fIlength\fP\fB);\fP
\fBvoid png_write_chunk_end (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_write_chunk_start (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIchunk_name\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
\fBvoid png_write_end (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fBvoid png_write_flush (png_structp \fIpng_ptr\fP\fB);\fP
\fBvoid png_write_image (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fIimage\fP\fB);\fP
\fBvoid png_write_info (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fBvoid png_write_info_before_PLTE (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
\fBvoid png_write_png (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fItransforms\fP\fB, png_voidp \fIparams\fP\fB);\fP
\fBvoid png_write_row (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fIrow\fP\fB);\fP
\fBvoid png_write_rows (png_structp \fP\fIpng_ptr\fP\fB, png_bytepp \fP\fIrow\fP\fB, png_uint_32 \fInum_rows\fP\fB);\fP
\fBvoid png_write_sig (png_structp \fIpng_ptr\fP\fB);\fP
.SH DESCRIPTION
The
.I libpng
library supports encoding, decoding, and various manipulations of
the Portable Network Graphics (PNG) format image files. It uses the
.IR zlib(3)
compression library.
Following is a copy of the libpng-manual.txt file that accompanies libpng.
.SH LIBPNG.TXT
libpng-manual.txt - A description on how to use and modify libpng
libpng version 1.6.16 - December 22, 2014
Updated and distributed by Glenn Randers-Pehrson
<glennrp at users.sourceforge.net>
Copyright (c) 1998-2014 Glenn Randers-Pehrson
This document is released under the libpng license.
For conditions of distribution and use, see the disclaimer
and license in png.h
Based on:
libpng versions 0.97, January 1998, through 1.6.16 - December 22, 2014
Updated and distributed by Glenn Randers-Pehrson
Copyright (c) 1998-2014 Glenn Randers-Pehrson
libpng 1.0 beta 6 - version 0.96 - May 28, 1997
Updated and distributed by Andreas Dilger
Copyright (c) 1996, 1997 Andreas Dilger
libpng 1.0 beta 2 - version 0.88 - January 26, 1996
For conditions of distribution and use, see copyright
notice in png.h. Copyright (c) 1995, 1996 Guy Eric
Schalnat, Group 42, Inc.
Updated/rewritten per request in the libpng FAQ
Copyright (c) 1995, 1996 Frank J. T. Wojcik
December 18, 1995 & January 20, 1996
TABLE OF CONTENTS
I. Introduction
II. Structures
III. Reading
IV. Writing
V. Simplified API
VI. Modifying/Customizing libpng
VII. MNG support
VIII. Changes to Libpng from version 0.88
IX. Changes to Libpng from version 1.0.x to 1.2.x
X. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x
XI. Changes to Libpng from version 1.4.x to 1.5.x
XII. Changes to Libpng from version 1.5.x to 1.6.x
XIII. Detecting libpng
XIV. Source code repository
XV. Coding style
XVI. Y2K Compliance in libpng
.SH I. Introduction
This file describes how to use and modify the PNG reference library
(known as libpng) for your own use. In addition to this
file, example.c is a good starting point for using the library, as
it is heavily commented and should include everything most people
will need. We assume that libpng is already installed; see the
INSTALL file for instructions on how to configure and install libpng.
For examples of libpng usage, see the files "example.c", "pngtest.c",
and the files in the "contrib" directory, all of which are included in
the libpng distribution.
Libpng was written as a companion to the PNG specification, as a way
of reducing the amount of time and effort it takes to support the PNG
file format in application programs.
The PNG specification (second edition), November 2003, is available as
a W3C Recommendation and as an ISO Standard (ISO/IEC 15948:2004 (E)) at
<http://www.w3.org/TR/2003/REC-PNG-20031110/
The W3C and ISO documents have identical technical content.
The PNG-1.2 specification is available at
<http://www.libpng.org/pub/png/documents/>. It is technically equivalent
to the PNG specification (second edition) but has some additional material.
The PNG-1.0 specification is available
as RFC 2083 <http://www.libpng.org/pub/png/documents/> and as a
W3C Recommendation <http://www.w3.org/TR/REC.png.html>.
Some additional chunks are described in the special-purpose public chunks
documents at <http://www.libpng.org/pub/png/documents/>.
Other information
about PNG, and the latest version of libpng, can be found at the PNG home
page, <http://www.libpng.org/pub/png/>.
Most users will not have to modify the library significantly; advanced
users may want to modify it more. All attempts were made to make it as
complete as possible, while keeping the code easy to understand.
Currently, this library only supports C. Support for other languages
is being considered.
Libpng has been designed to handle multiple sessions at one time,
to be easily modifiable, to be portable to the vast majority of
machines (ANSI, K&R, 16-, 32-, and 64-bit) available, and to be easy
to use. The ultimate goal of libpng is to promote the acceptance of
the PNG file format in whatever way possible. While there is still
work to be done (see the TODO file), libpng should cover the
majority of the needs of its users.
Libpng uses zlib for its compression and decompression of PNG files.
Further information about zlib, and the latest version of zlib, can
be found at the zlib home page, <http://www.info-zip.org/pub/infozip/zlib/>.
The zlib compression utility is a general purpose utility that is
useful for more than PNG files, and can be used without libpng.
See the documentation delivered with zlib for more details.
You can usually find the source files for the zlib utility wherever you
find the libpng source files.
Libpng is thread safe, provided the threads are using different
instances of the structures. Each thread should have its own
png_struct and png_info instances, and thus its own image.
Libpng does not protect itself against two threads using the
same instance of a structure.
.SH II. Structures
There are two main structures that are important to libpng, png_struct
and png_info. Both are internal structures that are no longer exposed
in the libpng interface (as of libpng 1.5.0).
The png_info structure is designed to provide information about the
PNG file. At one time, the fields of png_info were intended to be
directly accessible to the user. However, this tended to cause problems
with applications using dynamically loaded libraries, and as a result
a set of interface functions for png_info (the png_get_*() and png_set_*()
functions) was developed, and direct access to the png_info fields was
deprecated..
The png_struct structure is the object used by the library to decode a
single image. As of 1.5.0 this structure is also not exposed.
Almost all libpng APIs require a pointer to a png_struct as the first argument.
Many (in particular the png_set and png_get APIs) also require a pointer
to png_info as the second argument. Some application visible macros
defined in png.h designed for basic data access (reading and writing
integers in the PNG format) don't take a png_info pointer, but it's almost
always safe to assume that a (png_struct*) has to be passed to call an API
function.
You can have more than one png_info structure associated with an image,
as illustrated in pngtest.c, one for information valid prior to the
IDAT chunks and another (called "end_info" below) for things after them.
The png.h header file is an invaluable reference for programming with libpng.
And while I'm on the topic, make sure you include the libpng header file:
#include <png.h>
and also (as of libpng-1.5.0) the zlib header file, if you need it:
#include <zlib.h>
.SS Types
The png.h header file defines a number of integral types used by the
APIs. Most of these are fairly obvious; for example types corresponding
to integers of particular sizes and types for passing color values.
One exception is how non-integral numbers are handled. For application
convenience most APIs that take such numbers have C (double) arguments;
however, internally PNG, and libpng, use 32 bit signed integers and encode
the value by multiplying by 100,000. As of libpng 1.5.0 a convenience
macro PNG_FP_1 is defined in png.h along with a type (png_fixed_point)
which is simply (png_int_32).
All APIs that take (double) arguments also have a matching API that
takes the corresponding fixed point integer arguments. The fixed point
API has the same name as the floating point one with "_fixed" appended.
The actual range of values permitted in the APIs is frequently less than
the full range of (png_fixed_point) (\-21474 to +21474). When APIs require
a non-negative argument the type is recorded as png_uint_32 above. Consult
the header file and the text below for more information.
Special care must be take with sCAL chunk handling because the chunk itself
uses non-integral values encoded as strings containing decimal floating point
numbers. See the comments in the header file.
.SS Configuration
The main header file function declarations are frequently protected by C
preprocessing directives of the form:
src/Source/LibPNG/libpng.3 view on Meta::CPAN
declare-function
#endif
...
#ifdef PNG_feature_SUPPORTED
use-function
#endif
The library can be built without support for these APIs, although a
standard build will have all implemented APIs. Application programs
should check the feature macros before using an API for maximum
portability. From libpng 1.5.0 the feature macros set during the build
of libpng are recorded in the header file "pnglibconf.h" and this file
is always included by png.h.
If you don't need to change the library configuration from the default, skip to
the next section ("Reading").
Notice that some of the makefiles in the 'scripts' directory and (in 1.5.0) all
of the build project files in the 'projects' directory simply copy
scripts/pnglibconf.h.prebuilt to pnglibconf.h. This means that these build
systems do not permit easy auto-configuration of the library - they only
support the default configuration.
The easiest way to make minor changes to the libpng configuration when
auto-configuration is supported is to add definitions to the command line
using (typically) CPPFLAGS. For example:
CPPFLAGS=\-DPNG_NO_FLOATING_ARITHMETIC
will change the internal libpng math implementation for gamma correction and
other arithmetic calculations to fixed point, avoiding the need for fast
floating point support. The result can be seen in the generated pnglibconf.h -
make sure it contains the changed feature macro setting.
If you need to make more extensive configuration changes - more than one or two
feature macro settings - you can either add \-DPNG_USER_CONFIG to the build
command line and put a list of feature macro settings in pngusr.h or you can set
DFA_XTRA (a makefile variable) to a file containing the same information in the
form of 'option' settings.
A. Changing pnglibconf.h
A variety of methods exist to build libpng. Not all of these support
reconfiguration of pnglibconf.h. To reconfigure pnglibconf.h it must either be
rebuilt from scripts/pnglibconf.dfa using awk or it must be edited by hand.
Hand editing is achieved by copying scripts/pnglibconf.h.prebuilt to
pnglibconf.h and changing the lines defining the supported features, paying
very close attention to the 'option' information in scripts/pnglibconf.dfa
that describes those features and their requirements. This is easy to get
wrong.
B. Configuration using DFA_XTRA
Rebuilding from pnglibconf.dfa is easy if a functioning 'awk', or a later
variant such as 'nawk' or 'gawk', is available. The configure build will
automatically find an appropriate awk and build pnglibconf.h.
The scripts/pnglibconf.mak file contains a set of make rules for doing the
same thing if configure is not used, and many of the makefiles in the scripts
directory use this approach.
When rebuilding simply write a new file containing changed options and set
DFA_XTRA to the name of this file. This causes the build to append the new file
to the end of scripts/pnglibconf.dfa. The pngusr.dfa file should contain lines
of the following forms:
everything = off
This turns all optional features off. Include it at the start of pngusr.dfa to
make it easier to build a minimal configuration. You will need to turn at least
some features on afterward to enable either reading or writing code, or both.
option feature on
option feature off
Enable or disable a single feature. This will automatically enable other
features required by a feature that is turned on or disable other features that
require a feature which is turned off. Conflicting settings will cause an error
message to be emitted by awk.
setting feature default value
Changes the default value of setting 'feature' to 'value'. There are a small
number of settings listed at the top of pnglibconf.h, they are documented in the
source code. Most of these values have performance implications for the library
but most of them have no visible effect on the API. Some can also be overridden
from the API.
This method of building a customized pnglibconf.h is illustrated in
contrib/pngminim/*. See the "$(PNGCONF):" target in the makefile and
pngusr.dfa in these directories.
C. Configuration using PNG_USER_CONFIG
If \-DPNG_USER_CONFIG is added to the CPPFLAGS when pnglibconf.h is built,
the file pngusr.h will automatically be included before the options in
scripts/pnglibconf.dfa are processed. Your pngusr.h file should contain only
macro definitions turning features on or off or setting settings.
Apart from the global setting "everything = off" all the options listed above
can be set using macros in pngusr.h:
#define PNG_feature_SUPPORTED
is equivalent to:
option feature on
#define PNG_NO_feature
is equivalent to:
option feature off
#define PNG_feature value
is equivalent to:
setting feature default value
Notice that in both cases, pngusr.dfa and pngusr.h, the contents of the
pngusr file you supply override the contents of scripts/pnglibconf.dfa
If confusing or incomprehensible behavior results it is possible to
examine the intermediate file pnglibconf.dfn to find the full set of
dependency information for each setting and option. Simply locate the
feature in the file and read the C comments that precede it.
This method is also illustrated in the contrib/pngminim/* makefiles and
pngusr.h.
.SH III. Reading
We'll now walk you through the possible functions to call when reading
in a PNG file sequentially, briefly explaining the syntax and purpose
of each one. See example.c and png.h for more detail. While
progressive reading is covered in the next section, you will still
need some of the functions discussed in this section to read a PNG
file.
.SS Setup
You will want to do the I/O initialization(*) before you get into libpng,
so if it doesn't work, you don't have much to undo. Of course, you
will also want to insure that you are, in fact, dealing with a PNG
file. Libpng provides a simple check to see if a file is a PNG file.
To use it, pass in the first 1 to 8 bytes of the file to the function
png_sig_cmp(), and it will return 0 (false) if the bytes match the
corresponding bytes of the PNG signature, or nonzero (true) otherwise.
Of course, the more bytes you pass in, the greater the accuracy of the
prediction.
If you are intending to keep the file pointer open for use in libpng,
you must ensure you don't read more than 8 bytes from the beginning
of the file, and you also have to make a call to png_set_sig_bytes_read()
with the number of bytes you read from the beginning. Libpng will
then only check the bytes (if any) that your program didn't read.
(*): If you are not using the standard I/O functions, you will need
to replace them with custom functions. See the discussion under
Customizing libpng.
FILE *fp = fopen(file_name, "rb");
if (!fp)
{
return (ERROR);
}
fread(header, 1, number, fp);
is_png = !png_sig_cmp(header, 0, number);
if (!is_png)
{
return (NOT_PNG);
}
Next, png_struct and png_info need to be allocated and initialized. In
order to ensure that the size of these structures is correct even with a
dynamically linked libpng, there are functions to initialize and
allocate the structures. We also pass the library version, optional
pointers to error handling functions, and a pointer to a data struct for
use by the error functions, if necessary (the pointer and functions can
be NULL if the default error handlers are to be used). See the section
on Changes to Libpng below regarding the old initialization functions.
The structure allocation functions quietly return NULL if they fail to
create the structure, so your application should check for that.
png_structp png_ptr = png_create_read_struct
(PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
user_error_fn, user_warning_fn);
if (!png_ptr)
return (ERROR);
png_infop info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
{
png_destroy_read_struct(&png_ptr,
(png_infopp)NULL, (png_infopp)NULL);
return (ERROR);
}
If you want to use your own memory allocation routines,
use a libpng that was built with PNG_USER_MEM_SUPPORTED defined, and use
png_create_read_struct_2() instead of png_create_read_struct():
png_structp png_ptr = png_create_read_struct_2
(PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
user_error_fn, user_warning_fn, (png_voidp)
user_mem_ptr, user_malloc_fn, user_free_fn);
The error handling routines passed to png_create_read_struct()
and the memory alloc/free routines passed to png_create_struct_2()
are only necessary if you are not using the libpng supplied error
handling and memory alloc/free functions.
When libpng encounters an error, it expects to longjmp back
to your routine. Therefore, you will need to call setjmp and pass
your png_jmpbuf(png_ptr). If you read the file from different
routines, you will need to update the longjmp buffer every time you enter
a new routine that will call a png_*() function.
See your documentation of setjmp/longjmp for your compiler for more
information on setjmp/longjmp. See the discussion on libpng error
handling in the Customizing Libpng section below for more information
on the libpng error handling. If an error occurs, and libpng longjmp's
back to your setjmp, you will want to call png_destroy_read_struct() to
free any memory.
if (setjmp(png_jmpbuf(png_ptr)))
{
png_destroy_read_struct(&png_ptr, &info_ptr,
&end_info);
fclose(fp);
return (ERROR);
}
Pass (png_infopp)NULL instead of &end_info if you didn't create
an end_info structure.
If you would rather avoid the complexity of setjmp/longjmp issues,
you can compile libpng with PNG_NO_SETJMP, in which case
errors will result in a call to PNG_ABORT() which defaults to abort().
You can #define PNG_ABORT() to a function that does something
more useful than abort(), as long as your function does not
return.
Now you need to set up the input code. The default for libpng is to
use the C function fread(). If you use this, you will need to pass a
valid FILE * in the function png_init_io(). Be sure that the file is
opened in binary mode. If you wish to handle reading data in another
way, you need not call the png_init_io() function, but you must then
implement the libpng I/O methods discussed in the Customizing Libpng
section below.
png_init_io(png_ptr, fp);
If you had previously opened the file and read any of the signature from
the beginning in order to see if this was a PNG file, you need to let
libpng know that there are some bytes missing from the start of the file.
png_set_sig_bytes(png_ptr, number);
You can change the zlib compression buffer size to be used while
reading compressed data with
png_set_compression_buffer_size(png_ptr, buffer_size);
where the default size is 8192 bytes. Note that the buffer size
is changed immediately and the buffer is reallocated immediately,
instead of setting a flag to be acted upon later.
If you want CRC errors to be handled in a different manner than
the default, use
png_set_crc_action(png_ptr, crit_action, ancil_action);
The values for png_set_crc_action() say how libpng is to handle CRC errors in
ancillary and critical chunks, and whether to use the data contained
therein. Note that it is impossible to "discard" data in a critical
chunk.
Choices for (int) crit_action are
PNG_CRC_DEFAULT 0 error/quit
PNG_CRC_ERROR_QUIT 1 error/quit
PNG_CRC_WARN_USE 3 warn/use data
PNG_CRC_QUIET_USE 4 quiet/use data
PNG_CRC_NO_CHANGE 5 use the current value
src/Source/LibPNG/libpng.3 view on Meta::CPAN
PNG_CRC_WARN_DISCARD 2 warn/discard data
PNG_CRC_WARN_USE 3 warn/use data
PNG_CRC_QUIET_USE 4 quiet/use data
PNG_CRC_NO_CHANGE 5 use the current value
.SS Setting up callback code
You can set up a callback function to handle any unknown chunks in the
input stream. You must supply the function
read_chunk_callback(png_structp png_ptr,
png_unknown_chunkp chunk);
{
/* The unknown chunk structure contains your
chunk data, along with similar data for any other
unknown chunks: */
png_byte name[5];
png_byte *data;
png_size_t size;
/* Note that libpng has already taken care of
the CRC handling */
/* put your code here. Search for your chunk in the
unknown chunk structure, process it, and return one
of the following: */
return (\-n); /* chunk had an error */
return (0); /* did not recognize */
return (n); /* success */
}
(You can give your function another name that you like instead of
"read_chunk_callback")
To inform libpng about your function, use
png_set_read_user_chunk_fn(png_ptr, user_chunk_ptr,
read_chunk_callback);
This names not only the callback function, but also a user pointer that
you can retrieve with
png_get_user_chunk_ptr(png_ptr);
If you call the png_set_read_user_chunk_fn() function, then all unknown
chunks which the callback does not handle will be saved when read. You can
cause them to be discarded by returning '1' ("handled") instead of '0'. This
behavior will change in libpng 1.7 and the default handling set by the
png_set_keep_unknown_chunks() function, described below, will be used when the
callback returns 0. If you want the existing behavior you should set the global
default to PNG_HANDLE_CHUNK_IF_SAFE now; this is compatible with all current
versions of libpng and with 1.7. Libpng 1.6 issues a warning if you keep the
default, or PNG_HANDLE_CHUNK_NEVER, and the callback returns 0.
At this point, you can set up a callback function that will be
called after each row has been read, which you can use to control
a progress meter or the like. It's demonstrated in pngtest.c.
You must supply a function
void read_row_callback(png_structp png_ptr,
png_uint_32 row, int pass);
{
/* put your code here */
}
(You can give it another name that you like instead of "read_row_callback")
To inform libpng about your function, use
png_set_read_status_fn(png_ptr, read_row_callback);
When this function is called the row has already been completely processed and
the 'row' and 'pass' refer to the next row to be handled. For the
non-interlaced case the row that was just handled is simply one less than the
passed in row number, and pass will always be 0. For the interlaced case the
same applies unless the row value is 0, in which case the row just handled was
the last one from one of the preceding passes. Because interlacing may skip a
pass you cannot be sure that the preceding pass is just 'pass\-1', if you really
need to know what the last pass is record (row,pass) from the callback and use
the last recorded value each time.
src/Source/LibPNG/libpng.3 view on Meta::CPAN
.SS Unknown-chunk handling
Now you get to set the way the library processes unknown chunks in the
input PNG stream. Both known and unknown chunks will be read. Normal
behavior is that known chunks will be parsed into information in
various info_ptr members while unknown chunks will be discarded. This
behavior can be wasteful if your application will never use some known
chunk types. To change this, you can call:
png_set_keep_unknown_chunks(png_ptr, keep,
chunk_list, num_chunks);
keep - 0: default unknown chunk handling
1: ignore; do not keep
2: keep only if safe-to-copy
3: keep even if unsafe-to-copy
You can use these definitions:
PNG_HANDLE_CHUNK_AS_DEFAULT 0
PNG_HANDLE_CHUNK_NEVER 1
src/Source/LibPNG/libpng.3 view on Meta::CPAN
num_chunks - number of chunks affected; if 0, all
unknown chunks are affected. If positive,
only the chunks in the list are affected,
and if negative all unknown chunks and
all known chunks except for the IHDR,
PLTE, tRNS, IDAT, and IEND chunks are
affected.
Unknown chunks declared in this way will be saved as raw data onto a
list of png_unknown_chunk structures. If a chunk that is normally
known to libpng is named in the list, it will be handled as unknown,
according to the "keep" directive. If a chunk is named in successive
instances of png_set_keep_unknown_chunks(), the final instance will
take precedence. The IHDR and IEND chunks should not be named in
chunk_list; if they are, libpng will process them normally anyway.
If you know that your application will never make use of some particular
chunks, use PNG_HANDLE_CHUNK_NEVER (or 1) as demonstrated below.
Here is an example of the usage of png_set_keep_unknown_chunks(),
where the private "vpAg" chunk will later be processed by a user chunk
callback function:
png_byte vpAg[5]={118, 112, 65, 103, (png_byte) '\0'};
#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
png_byte unused_chunks[]=
{
104, 73, 83, 84, (png_byte) '\0', /* hIST */
105, 84, 88, 116, (png_byte) '\0', /* iTXt */
112, 67, 65, 76, (png_byte) '\0', /* pCAL */
115, 67, 65, 76, (png_byte) '\0', /* sCAL */
115, 80, 76, 84, (png_byte) '\0', /* sPLT */
116, 73, 77, 69, (png_byte) '\0', /* tIME */
};
#endif
...
#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
/* ignore all unknown chunks
* (use global setting "2" for libpng16 and earlier):
*/
png_set_keep_unknown_chunks(read_ptr, 2, NULL, 0);
/* except for vpAg: */
png_set_keep_unknown_chunks(read_ptr, 2, vpAg, 1);
/* also ignore unused known chunks: */
png_set_keep_unknown_chunks(read_ptr, 1, unused_chunks,
(int)(sizeof unused_chunks)/5);
#endif
.SS User limits
The PNG specification allows the width and height of an image to be as
large as 2^(31\-1 (0x7fffffff), or about 2.147 billion rows and columns.
Larger images will be rejected immediately with a png_error() call. If
you wish to reduce these limits, you can use
png_set_user_limits(png_ptr, width_max, height_max);
to set your own limits (libpng may reject some very wide images
anyway because of potential buffer overflow conditions).
You should put this statement after you create the PNG structure and
before calling png_read_info(), png_read_png(), or png_process_data().
When writing a PNG datastream, put this statement before calling
png_write_info() or png_write_png().
If you need to retrieve the limits that are being applied, use
width_max = png_get_user_width_max(png_ptr);
height_max = png_get_user_height_max(png_ptr);
The PNG specification sets no limit on the number of ancillary chunks
allowed in a PNG datastream. You can impose a limit on the total number
of sPLT, tEXt, iTXt, zTXt, and unknown chunks that will be stored, with
png_set_chunk_cache_max(png_ptr, user_chunk_cache_max);
where 0x7fffffffL means unlimited. You can retrieve this limit with
chunk_cache_max = png_get_chunk_cache_max(png_ptr);
You can also set a limit on the amount of memory that a compressed chunk
other than IDAT can occupy, with
png_set_chunk_malloc_max(png_ptr, user_chunk_malloc_max);
and you can retrieve the limit with
chunk_malloc_max = png_get_chunk_malloc_max(png_ptr);
Any chunks that would cause either of these limits to be exceeded will
be ignored.
.SS Information about your system
If you intend to display the PNG or to incorporate it in other image data you
need to tell libpng information about your display or drawing surface so that
libpng can convert the values in the image to match the display.
From libpng-1.5.4 this information can be set before reading the PNG file
header. In earlier versions png_set_gamma() existed but behaved incorrectly if
called before the PNG file header had been read and png_set_alpha_mode() did not
exist.
If you need to support versions prior to libpng-1.5.4 test the version number
as illustrated below using "PNG_LIBPNG_VER >= 10504" and follow the procedures
described in the appropriate manual page.
You give libpng the encoding expected by your system expressed as a 'gamma'
value. You can also specify a default encoding for the PNG file in
case the required information is missing from the file. By default libpng
assumes that the PNG data matches your system, to keep this default call:
png_set_gamma(png_ptr, screen_gamma, output_gamma);
or you can use the fixed point equivalent:
png_set_gamma_fixed(png_ptr, PNG_FP_1*screen_gamma,
PNG_FP_1*output_gamma);
If you don't know the gamma for your system it is probably 2.2 - a good
approximation to the IEC standard for display systems (sRGB). If images are
too contrasty or washed out you got the value wrong - check your system
documentation!
Many systems permit the system gamma to be changed via a lookup table in the
display driver, a few systems, including older Macs, change the response by
default. As of 1.5.4 three special values are available to handle common
src/Source/LibPNG/libpng.3 view on Meta::CPAN
to preserve overall accuracy.
The output_gamma value expresses how to decode the output values, not how
they are encoded. The values used correspond to the normal numbers used to
describe the overall gamma of a computer display system; for example 2.2 for
an sRGB conformant system. The values are scaled by 100000 in the _fixed
version of the API (so 220000 for sRGB.)
The inverse of the value is always used to provide a default for the PNG file
encoding if it has no gAMA chunk and if png_set_gamma() has not been called
to override the PNG gamma information.
When the ALPHA_OPTIMIZED mode is selected the output gamma is used to encode
opaque pixels however pixels with lower alpha values are not encoded,
regardless of the output gamma setting.
When the standard Porter Duff handling is requested with mode 1 the output
encoding is set to be linear and the output_gamma value is only relevant
as a default for input data that has no gamma information. The linear output
encoding will be overridden if png_set_gamma() is called - the results may be
highly unexpected!
The following numbers are derived from the sRGB standard and the research
behind it. sRGB is defined to be approximated by a PNG gAMA chunk value of
0.45455 (1/2.2) for PNG. The value implicitly includes any viewing
correction required to take account of any differences in the color
environment of the original scene and the intended display environment; the
value expresses how to *decode* the image for display, not how the original
data was *encoded*.
src/Source/LibPNG/libpng.3 view on Meta::CPAN
The Mac value is deduced from the sRGB based on an assumption that the actual
extra viewing correction used in early Mac display systems was implemented as
a power 1.45 lookup table.
Any system where a programmable lookup table is used or where the behavior of
the final display device characteristics can be changed requires system
specific code to obtain the current characteristic. However this can be
difficult and most PNG gamma correction only requires an approximate value.
By default, if png_set_alpha_mode() is not called, libpng assumes that all
values are unencoded, linear, values and that the output device also has a
linear characteristic. This is only very rarely correct - it is invariably
better to call png_set_alpha_mode() with PNG_DEFAULT_sRGB than rely on the
default if you don't know what the right answer is!
The special value PNG_GAMMA_MAC_18 indicates an older Mac system (pre Mac OS
10.6) which used a correction table to implement a somewhat lower gamma on an
otherwise sRGB system.
Both these values are reserved (not simple gamma values) in order to allow
more precise correction internally in the future.
NOTE: the values can be passed to either the fixed or floating
point APIs, but the floating point API will also accept floating point
values.
The second thing you may need to tell libpng about is how your system handles
alpha channel information. Some, but not all, PNG files contain an alpha
channel. To display these files correctly you need to compose the data onto a
suitable background, as described in the PNG specification.
Libpng only supports composing onto a single color (using png_set_background;
see below). Otherwise you must do the composition yourself and, in this case,
you may need to call png_set_alpha_mode:
#if PNG_LIBPNG_VER >= 10504
png_set_alpha_mode(png_ptr, mode, screen_gamma);
#else
png_set_gamma(png_ptr, screen_gamma, 1.0/screen_gamma);
#endif
The screen_gamma value is the same as the argument to png_set_gamma; however,
how it affects the output depends on the mode. png_set_alpha_mode() sets the
file gamma default to 1/screen_gamma, so normally you don't need to call
png_set_gamma. If you need different defaults call png_set_gamma() before
png_set_alpha_mode() - if you call it after it will override the settings made
by png_set_alpha_mode().
The mode is as follows:
PNG_ALPHA_PNG: The data is encoded according to the PNG
specification. Red, green and blue, or gray, components are
gamma encoded color values and are not premultiplied by the
alpha value. The alpha value is a linear measure of the
contribution of the pixel to the corresponding final output pixel.
You should normally use this format if you intend to perform
src/Source/LibPNG/libpng.3 view on Meta::CPAN
storing color channel values that have been scaled by the alpha. The
advantage is that the color channels can be resampled (the image can be
scaled) in this form. The disadvantage is that normal practice is to store
linear, not (gamma) encoded, values and this requires 16-bit channels for
still images rather than the 8-bit channels that are just about sufficient if
gamma encoding is used. In addition all non-transparent pixel values,
including completely opaque ones, must be gamma encoded to produce the final
image. These are the 'STANDARD', 'ASSOCIATED' or 'PREMULTIPLIED' modes
described below (the latter being the two common names for associated alpha
color channels). Note that PNG files always contain non-associated color
channels; png_set_alpha_mode() with one of the modes causes the decoder to
convert the pixels to an associated form before returning them to your
application.
Since it is not necessary to perform arithmetic on opaque color values so
long as they are not to be resampled and are in the final color space it is
possible to optimize the handling of alpha by storing the opaque pixels in
the PNG format (adjusted for the output color space) while storing partially
opaque pixels in the standard, linear, format. The accuracy required for
standard alpha composition is relatively low, because the pixels are
isolated, therefore typically the accuracy loss in storing 8-bit linear
values is acceptable. (This is not true if the alpha channel is used to
simulate transparency over large areas - use 16 bits or the PNG mode in
this case!) This is the 'OPTIMIZED' mode. For this mode a pixel is
treated as opaque only if the alpha value is equal to the maximum value.
PNG_ALPHA_STANDARD: The data libpng produces is encoded in the
standard way assumed by most correctly written graphics software.
The gamma encoding will be removed by libpng and the
linear component values will be pre-multiplied by the
alpha channel.
With this format the final image must be re-encoded to
match the display gamma before the image is displayed.
If your system doesn't do that, yet still seems to
perform arithmetic on the pixels without decoding them,
it is broken - check out the modes below.
With PNG_ALPHA_STANDARD libpng always produces linear
component values, whatever screen_gamma you supply. The
screen_gamma value is, however, used as a default for
the file gamma if the PNG file has no gamma information.
If you call png_set_gamma() after png_set_alpha_mode() you
will override the linear encoding. Instead the
pre-multiplied pixel values will be gamma encoded but
the alpha channel will still be linear. This may
actually match the requirements of some broken software,
but it is unlikely.
While linear 8-bit data is often used it has
insufficient precision for any image with a reasonable
dynamic range. To avoid problems, and if your software
supports it, use png_set_expand_16() to force all
components to 16 bits.
PNG_ALPHA_OPTIMIZED: This mode is the same as PNG_ALPHA_STANDARD
except that completely opaque pixels are gamma encoded according to
the screen_gamma value. Pixels with alpha less than 1.0
will still have linear components.
Use this format if you have control over your
compositing software and so don't do other arithmetic
(such as scaling) on the data you get from libpng. Your
compositing software can simply copy opaque pixels to
the output but still has linear values for the
non-opaque pixels.
In normal compositing, where the alpha channel encodes
partial pixel coverage (as opposed to broad area
translucency), the inaccuracies of the 8-bit
representation of non-opaque pixels are irrelevant.
You can also try this format if your software is broken;
src/Source/LibPNG/libpng.3 view on Meta::CPAN
broken because, in practice, no implementation that uses this choice
correctly undoes the encoding before handling alpha composition. Use this
choice only if other serious errors in the software or hardware you use
mandate it. In most cases of broken software or hardware the bug in the
final display manifests as a subtle halo around composited parts of the
image. You may not even perceive this as a halo; the composited part of
the image may simply appear separate from the background, as though it had
been cut out of paper and pasted on afterward.
If you don't have to deal with bugs in software or hardware, or if you can fix
them, there are three recommended ways of using png_set_alpha_mode():
png_set_alpha_mode(png_ptr, PNG_ALPHA_PNG,
screen_gamma);
You can do color correction on the result (libpng does not currently
support color correction internally). When you handle the alpha channel
you need to undo the gamma encoding and multiply out the alpha.
png_set_alpha_mode(png_ptr, PNG_ALPHA_STANDARD,
screen_gamma);
png_set_expand_16(png_ptr);
If you are using the high level interface, don't call png_set_expand_16();
instead pass PNG_TRANSFORM_EXPAND_16 to the interface.
With this mode you can't do color correction, but you can do arithmetic,
including composition and scaling, on the data without further processing.
png_set_alpha_mode(png_ptr, PNG_ALPHA_OPTIMIZED,
screen_gamma);
You can avoid the expansion to 16-bit components with this mode, but you
lose the ability to scale the image or perform other linear arithmetic.
All you can do is compose the result onto a matching output. Since this
mode is libpng-specific you also need to write your own composition
software.
The following are examples of calls to png_set_alpha_mode to achieve the
required overall gamma correction and, where necessary, alpha
premultiplication.
png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
This is the default libpng handling of the alpha channel - it is not
pre-multiplied into the color components. In addition the call states
that the output is for a sRGB system and causes all PNG files without gAMA
chunks to be assumed to be encoded using sRGB.
png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
In this case the output is assumed to be something like an sRGB conformant
display preceeded by a power-law lookup table of power 1.45. This is how
early Mac systems behaved.
png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_GAMMA_LINEAR);
This is the classic Jim Blinn approach and will work in academic
environments where everything is done by the book. It has the shortcoming
of assuming that input PNG data with no gamma information is linear - this
is unlikely to be correct unless the PNG files where generated locally.
Most of the time the output precision will be so low as to show
significant banding in dark areas of the image.
png_set_expand_16(pp);
png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_DEFAULT_sRGB);
This is a somewhat more realistic Jim Blinn inspired approach. PNG files
are assumed to have the sRGB encoding if not marked with a gamma value and
the output is always 16 bits per component. This permits accurate scaling
and processing of the data. If you know that your input PNG files were
generated locally you might need to replace PNG_DEFAULT_sRGB with the
correct value for your system.
png_set_alpha_mode(pp, PNG_ALPHA_OPTIMIZED, PNG_DEFAULT_sRGB);
If you just need to composite the PNG image onto an existing background
and if you control the code that does this you can use the optimization
setting. In this case you just copy completely opaque pixels to the
output. For pixels that are not completely transparent (you just skip
those) you do the composition math using png_composite or png_composite_16
below then encode the resultant 8-bit or 16-bit values to match the output
encoding.
Other cases
If neither the PNG nor the standard linear encoding work for you because
of the software or hardware you use then you have a big problem. The PNG
case will probably result in halos around the image. The linear encoding
will probably result in a washed out, too bright, image (it's actually too
contrasty.) Try the ALPHA_OPTIMIZED mode above - this will probably
substantially reduce the halos. Alternatively try:
png_set_alpha_mode(pp, PNG_ALPHA_BROKEN, PNG_DEFAULT_sRGB);
This option will also reduce the halos, but there will be slight dark
halos round the opaque parts of the image where the background is light.
In the OPTIMIZED mode the halos will be light halos where the background
is dark. Take your pick - the halos are unavoidable unless you can get
your hardware/software fixed! (The OPTIMIZED approach is slightly
faster.)
When the default gamma of PNG files doesn't match the output gamma.
If you have PNG files with no gamma information png_set_alpha_mode allows
you to provide a default gamma, but it also sets the ouput gamma to the
matching value. If you know your PNG files have a gamma that doesn't
match the output you can take advantage of the fact that
png_set_alpha_mode always sets the output gamma but only sets the PNG
default if it is not already set:
png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
The first call sets both the default and the output gamma values, the
second call overrides the output gamma without changing the default. This
is easier than achieving the same effect with png_set_gamma. You must use
PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will
fire if more than one call to png_set_alpha_mode and png_set_background is
made in the same read operation, however multiple calls with PNG_ALPHA_PNG
are ignored.
If you don't need, or can't handle, the alpha channel you can call
png_set_background() to remove it by compositing against a fixed color. Don't
call png_set_strip_alpha() to do this - it will leave spurious pixel values in
transparent parts of this image.
png_set_background(png_ptr, &background_color,
PNG_BACKGROUND_GAMMA_SCREEN, 0, 1);
The background_color is an RGB or grayscale value according to the data format
libpng will produce for you. Because you don't yet know the format of the PNG
file, if you call png_set_background at this point you must arrange for the
format produced by libpng to always have 8-bit or 16-bit components and then
store the color as an 8-bit or 16-bit color as appropriate. The color contains
separate gray and RGB component values, so you can let libpng produce gray or
RGB output according to the input format, but low bit depth grayscale images
must always be converted to at least 8-bit format. (Even though low bit depth
grayscale images can't have an alpha channel they can have a transparent
color!)
You set the transforms you need later, either as flags to the high level
interface or libpng API calls for the low level interface. For reference the
settings and API calls required are:
8-bit values:
PNG_TRANSFORM_SCALE_16 | PNG_EXPAND
png_set_expand(png_ptr); png_set_scale_16(png_ptr);
If you must get exactly the same inaccurate results
produced by default in versions prior to libpng-1.5.4,
use PNG_TRANSFORM_STRIP_16 and png_set_strip_16(png_ptr)
instead.
16-bit values:
PNG_TRANSFORM_EXPAND_16
png_set_expand_16(png_ptr);
In either case palette image data will be expanded to RGB. If you just want
color data you can add PNG_TRANSFORM_GRAY_TO_RGB or png_set_gray_to_rgb(png_ptr)
to the list.
Calling png_set_background before the PNG file header is read will not work
prior to libpng-1.5.4. Because the failure may result in unexpected warnings or
errors it is therefore much safer to call png_set_background after the head has
been read. Unfortunately this means that prior to libpng-1.5.4 it cannot be
used with the high level interface.
.SS The high-level read interface
At this point there are two ways to proceed; through the high-level
read interface, or through a sequence of low-level read operations.
You can use the high-level interface if (a) you are willing to read
the entire image into memory, and (b) the input transformations
you want to do are limited to the following set:
src/Source/LibPNG/libpng.3 view on Meta::CPAN
PNG_TRANSFORM_INVERT_ALPHA Change alpha from opacity
to transparency
PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
PNG_TRANSFORM_GRAY_TO_RGB Expand grayscale samples
to RGB (or GA to RGBA)
PNG_TRANSFORM_EXPAND_16 Expand samples to 16 bits
(This excludes setting a background color, doing gamma transformation,
quantizing, and setting filler.) If this is the case, simply do this:
png_read_png(png_ptr, info_ptr, png_transforms, NULL)
where png_transforms is an integer containing the bitwise OR of some
set of transformation flags. This call is equivalent to png_read_info(),
followed the set of transformations indicated by the transform mask,
then png_read_image(), and finally png_read_end().
(The final parameter of this call is not yet used. Someday it might point
to transformation parameters required by some future input transform.)
You must use png_transforms and not call any png_set_transform() functions
when you use png_read_png().
After you have called png_read_png(), you can retrieve the image data
with
row_pointers = png_get_rows(png_ptr, info_ptr);
where row_pointers is an array of pointers to the pixel data for each row:
png_bytep row_pointers[height];
If you know your image size and pixel size ahead of time, you can allocate
row_pointers prior to calling png_read_png() with
if (height > PNG_UINT_32_MAX/(sizeof (png_byte)))
png_error (png_ptr,
"Image is too tall to process in memory");
if (width > PNG_UINT_32_MAX/pixel_size)
png_error (png_ptr,
"Image is too wide to process in memory");
row_pointers = png_malloc(png_ptr,
height*(sizeof (png_bytep)));
for (int i=0; i<height, i++)
row_pointers[i]=NULL; /* security precaution */
for (int i=0; i<height, i++)
row_pointers[i]=png_malloc(png_ptr,
width*pixel_size);
png_set_rows(png_ptr, info_ptr, &row_pointers);
Alternatively you could allocate your image in one big block and define
row_pointers[i] to point into the proper places in your block.
If you use png_set_rows(), the application is responsible for freeing
row_pointers (and row_pointers[i], if they were separately allocated).
If you don't allocate row_pointers ahead of time, png_read_png() will
do it, and it'll be free'ed by libpng when you call png_destroy_*().
.SS The low-level read interface
If you are going the low-level route, you are now ready to read all
the file information up to the actual image data. You do this with a
call to png_read_info().
png_read_info(png_ptr, info_ptr);
This will process all chunks up to but not including the image data.
This also copies some of the data from the PNG file into the decode structure
for use in later transformations. Important information copied in is:
1) The PNG file gamma from the gAMA chunk. This overwrites the default value
provided by an earlier call to png_set_gamma or png_set_alpha_mode.
2) Prior to libpng-1.5.4 the background color from a bKGd chunk. This
damages the information provided by an earlier call to png_set_background
resulting in unexpected behavior. Libpng-1.5.4 no longer does this.
3) The number of significant bits in each component value. Libpng uses this to
optimize gamma handling by reducing the internal lookup table sizes.
4) The transparent color information from a tRNS chunk. This can be modified by
a later call to png_set_tRNS.
.SS Querying the info structure
Functions are used to get the information from the info_ptr once it
has been read. Note that these fields may not be completely filled
in until png_read_end() has read the chunk data following the image.
png_get_IHDR(png_ptr, info_ptr, &width, &height,
&bit_depth, &color_type, &interlace_type,
&compression_type, &filter_method);
width - holds the width of the image
in pixels (up to 2^31).
height - holds the height of the image
in pixels (up to 2^31).
bit_depth - holds the bit depth of one of the
src/Source/LibPNG/libpng.3 view on Meta::CPAN
filter_method - (must be PNG_FILTER_TYPE_BASE
for PNG 1.0, and can also be
PNG_INTRAPIXEL_DIFFERENCING if
the PNG datastream is embedded in
a MNG-1.0 datastream)
Any or all of interlace_type, compression_type, or
filter_method can be NULL if you are
not interested in their values.
Note that png_get_IHDR() returns 32-bit data into
the application's width and height variables.
This is an unsafe situation if these are 16-bit
variables. In such situations, the
png_get_image_width() and png_get_image_height()
functions described below are safer.
width = png_get_image_width(png_ptr,
info_ptr);
height = png_get_image_height(png_ptr,
info_ptr);
bit_depth = png_get_bit_depth(png_ptr,
info_ptr);
color_type = png_get_color_type(png_ptr,
info_ptr);
interlace_type = png_get_interlace_type(png_ptr,
info_ptr);
compression_type = png_get_compression_type(png_ptr,
info_ptr);
filter_method = png_get_filter_type(png_ptr,
info_ptr);
channels = png_get_channels(png_ptr, info_ptr);
channels - number of channels of info for the
color type (valid values are 1 (GRAY,
PALETTE), 2 (GRAY_ALPHA), 3 (RGB),
4 (RGB_ALPHA or RGB + filler byte))
rowbytes = png_get_rowbytes(png_ptr, info_ptr);
rowbytes - number of bytes needed to hold a row
signature = png_get_signature(png_ptr, info_ptr);
signature - holds the signature read from the
file (if any). The data is kept in
the same offset it would be if the
whole signature were read (i.e. if an
application had already read in 4
bytes of signature before starting
libpng, the remaining 4 bytes would
be in signature[4] through signature[7]
(see png_set_sig_bytes())).
These are also important, but their validity depends on whether the chunk
has been read. The png_get_valid(png_ptr, info_ptr, PNG_INFO_<chunk>) and
png_get_<chunk>(png_ptr, info_ptr, ...) functions return non-zero if the
data has been read, or zero if it is missing. The parameters to the
png_get_<chunk> are set directly if they are simple data types, or a
pointer into the info_ptr is returned for any complex types.
The colorspace data from gAMA, cHRM, sRGB, iCCP, and sBIT chunks
is simply returned to give the application information about how the
image was encoded. Libpng itself only does transformations using the file
gamma when combining semitransparent pixels with the background color, and,
since libpng-1.6.0, when converting between 8-bit sRGB and 16-bit linear pixels
within the simplified API. Libpng also uses the file gamma when converting
RGB to gray, beginning with libpng-1.0.5, if the application calls
png_set_rgb_to_gray()).
png_get_PLTE(png_ptr, info_ptr, &palette,
&num_palette);
palette - the palette for the file
(array of png_color)
num_palette - number of entries in the palette
png_get_gAMA(png_ptr, info_ptr, &file_gamma);
png_get_gAMA_fixed(png_ptr, info_ptr, &int_file_gamma);
file_gamma - the gamma at which the file is
written (PNG_INFO_gAMA)
int_file_gamma - 100,000 times the gamma at which the
file is written
png_get_cHRM(png_ptr, info_ptr, &white_x, &white_y, &red_x,
&red_y, &green_x, &green_y, &blue_x, &blue_y)
png_get_cHRM_XYZ(png_ptr, info_ptr, &red_X, &red_Y, &red_Z,
&green_X, &green_Y, &green_Z, &blue_X, &blue_Y,
&blue_Z)
png_get_cHRM_fixed(png_ptr, info_ptr, &int_white_x,
&int_white_y, &int_red_x, &int_red_y,
&int_green_x, &int_green_y, &int_blue_x,
&int_blue_y)
png_get_cHRM_XYZ_fixed(png_ptr, info_ptr, &int_red_X, &int_red_Y,
&int_red_Z, &int_green_X, &int_green_Y,
&int_green_Z, &int_blue_X, &int_blue_Y,
&int_blue_Z)
{white,red,green,blue}_{x,y}
A color space encoding specified using the
chromaticities of the end points and the
white point. (PNG_INFO_cHRM)
{red,green,blue}_{X,Y,Z}
A color space encoding specified using the
encoding end points - the CIE tristimulus
specification of the intended color of the red,
green and blue channels in the PNG RGB data.
The white point is simply the sum of the three
end points. (PNG_INFO_cHRM)
png_get_sRGB(png_ptr, info_ptr, &srgb_intent);
srgb_intent - the rendering intent (PNG_INFO_sRGB)
The presence of the sRGB chunk
means that the pixel data is in the
sRGB color space. This chunk also
implies specific values of gAMA and
cHRM.
png_get_iCCP(png_ptr, info_ptr, &name,
&compression_type, &profile, &proflen);
name - The profile name.
compression_type - The compression type; always
PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
You may give NULL to this argument to
ignore it.
profile - International Color Consortium color
profile data. May contain NULs.
proflen - length of profile data in bytes.
png_get_sBIT(png_ptr, info_ptr, &sig_bit);
sig_bit - the number of significant bits for
(PNG_INFO_sBIT) each of the gray,
red, green, and blue channels,
whichever are appropriate for the
given color type (png_color_16)
png_get_tRNS(png_ptr, info_ptr, &trans_alpha,
&num_trans, &trans_color);
trans_alpha - array of alpha (transparency)
entries for palette (PNG_INFO_tRNS)
num_trans - number of transparent entries
(PNG_INFO_tRNS)
trans_color - graylevel or color sample values of
the single transparent color for
non-paletted images (PNG_INFO_tRNS)
png_get_hIST(png_ptr, info_ptr, &hist);
(PNG_INFO_hIST)
hist - histogram of palette (array of
png_uint_16)
png_get_tIME(png_ptr, info_ptr, &mod_time);
mod_time - time image was last modified
(PNG_VALID_tIME)
png_get_bKGD(png_ptr, info_ptr, &background);
background - background color (of type
png_color_16p) (PNG_VALID_bKGD)
valid 16-bit red, green and blue
values, regardless of color_type
num_comments = png_get_text(png_ptr, info_ptr,
&text_ptr, &num_text);
num_comments - number of comments
text_ptr - array of png_text holding image
comments
text_ptr[i].compression - type of compression used
on "text" PNG_TEXT_COMPRESSION_NONE
PNG_TEXT_COMPRESSION_zTXt
PNG_ITXT_COMPRESSION_NONE
PNG_ITXT_COMPRESSION_zTXt
text_ptr[i].key - keyword for comment. Must contain
1-79 characters.
src/Source/LibPNG/libpng.3 view on Meta::CPAN
text_ptr[i].lang - language of comment (empty
string for unknown).
text_ptr[i].lang_key - keyword in UTF-8
(empty string for unknown).
Note that the itxt_length, lang, and lang_key
members of the text_ptr structure only exist when the
library is built with iTXt chunk support. Prior to
libpng-1.4.0 the library was built by default without
iTXt support. Also note that when iTXt is supported,
they contain NULL pointers when the "compression"
field contains PNG_TEXT_COMPRESSION_NONE or
PNG_TEXT_COMPRESSION_zTXt.
num_text - number of comments (same as
num_comments; you can put NULL here
to avoid the duplication)
Note while png_set_text() will accept text, language,
and translated keywords that can be NULL pointers, the
structure returned by png_get_text will always contain
regular zero-terminated C strings. They might be
empty strings but they will never be NULL pointers.
num_spalettes = png_get_sPLT(png_ptr, info_ptr,
&palette_ptr);
num_spalettes - number of sPLT chunks read.
palette_ptr - array of palette structures holding
contents of one or more sPLT chunks
read.
png_get_oFFs(png_ptr, info_ptr, &offset_x, &offset_y,
&unit_type);
offset_x - positive offset from the left edge
of the screen (can be negative)
offset_y - positive offset from the top edge
of the screen (can be negative)
unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
png_get_pHYs(png_ptr, info_ptr, &res_x, &res_y,
&unit_type);
res_x - pixels/unit physical resolution in
x direction
res_y - pixels/unit physical resolution in
x direction
unit_type - PNG_RESOLUTION_UNKNOWN,
PNG_RESOLUTION_METER
png_get_sCAL(png_ptr, info_ptr, &unit, &width,
&height)
unit - physical scale units (an integer)
width - width of a pixel in physical scale units
height - height of a pixel in physical scale units
(width and height are doubles)
png_get_sCAL_s(png_ptr, info_ptr, &unit, &width,
&height)
unit - physical scale units (an integer)
width - width of a pixel in physical scale units
(expressed as a string)
height - height of a pixel in physical scale units
(width and height are strings like "2.54")
num_unknown_chunks = png_get_unknown_chunks(png_ptr,
info_ptr, &unknowns)
unknowns - array of png_unknown_chunk
structures holding unknown chunks
unknowns[i].name - name of unknown chunk
unknowns[i].data - data of unknown chunk
unknowns[i].size - size of unknown chunk's data
unknowns[i].location - position of chunk in file
The value of "i" corresponds to the order in which the
chunks were read from the PNG file or inserted with the
png_set_unknown_chunks() function.
The value of "location" is a bitwise "or" of
PNG_HAVE_IHDR (0x01)
PNG_HAVE_PLTE (0x02)
PNG_AFTER_IDAT (0x08)
The data from the pHYs chunk can be retrieved in several convenient
forms:
res_x = png_get_x_pixels_per_meter(png_ptr,
info_ptr)
res_y = png_get_y_pixels_per_meter(png_ptr,
info_ptr)
res_x_and_y = png_get_pixels_per_meter(png_ptr,
info_ptr)
res_x = png_get_x_pixels_per_inch(png_ptr,
info_ptr)
res_y = png_get_y_pixels_per_inch(png_ptr,
info_ptr)
res_x_and_y = png_get_pixels_per_inch(png_ptr,
info_ptr)
aspect_ratio = png_get_pixel_aspect_ratio(png_ptr,
info_ptr)
Each of these returns 0 [signifying "unknown"] if
the data is not present or if res_x is 0;
res_x_and_y is 0 if res_x != res_y
Note that because of the way the resolutions are
stored internally, the inch conversions won't
come out to exactly even number. For example,
72 dpi is stored as 0.28346 pixels/meter, and
when this is retrieved it is 71.9988 dpi, so
be sure to round the returned value appropriately
if you want to display a reasonable-looking result.
The data from the oFFs chunk can be retrieved in several convenient
forms:
x_offset = png_get_x_offset_microns(png_ptr, info_ptr);
y_offset = png_get_y_offset_microns(png_ptr, info_ptr);
x_offset = png_get_x_offset_inches(png_ptr, info_ptr);
y_offset = png_get_y_offset_inches(png_ptr, info_ptr);
Each of these returns 0 [signifying "unknown" if both
x and y are 0] if the data is not present or if the
chunk is present but the unit is the pixel. The
remark about inexact inch conversions applies here
as well, because a value in inches can't always be
converted to microns and back without some loss
of precision.
For more information, see the
PNG specification for chunk contents. Be careful with trusting
rowbytes, as some of the transformations could increase the space
needed to hold a row (expand, filler, gray_to_rgb, etc.).
See png_read_update_info(), below.
A quick word about text_ptr and num_text. PNG stores comments in
keyword/text pairs, one pair per chunk, with no limit on the number
of text chunks, and a 2^31 byte limit on their size. While there are
suggested keywords, there is no requirement to restrict the use to these
strings. It is strongly suggested that keywords and text be sensible
to humans (that's the point), so don't use abbreviations. Non-printing
symbols are not allowed. See the PNG specification for more details.
There is also no requirement to have text after the keyword.
Keywords should be limited to 79 Latin-1 characters without leading or
trailing spaces, but non-consecutive spaces are allowed within the
keyword. It is possible to have the same keyword any number of times.
The text_ptr is an array of png_text structures, each holding a
pointer to a language string, a pointer to a keyword and a pointer to
a text string. The text string, language code, and translated
keyword may be empty or NULL pointers. The keyword/text
pairs are put into the array in the order that they are received.
However, some or all of the text chunks may be after the image, so, to
make sure you have read all the text chunks, don't mess with these
until after you read the stuff after the image. This will be
mentioned again below in the discussion that goes with png_read_end().
.SS Input transformations
After you've read the header information, you can set up the library
to handle any special transformations of the image data. The various
ways to transform the data will be described in the order that they
should occur. This is important, as some of these change the color
type and/or bit depth of the data, and some others only work on
certain color types and bit depths.
Transformations you request are ignored if they don't have any meaning for a
particular input data format. However some transformations can have an effect
as a result of a previous transformation. If you specify a contradictory set of
transformations, for example both adding and removing the alpha channel, you
cannot predict the final result.
The color used for the transparency values should be supplied in the same
format/depth as the current image data. It is stored in the same format/depth
as the image data in a tRNS chunk, so this is what libpng expects for this data.
The color used for the background value depends on the need_expand argument as
described below.
Data will be decoded into the supplied row buffers packed into bytes
unless the library has been told to transform it into another format.
For example, 4 bit/pixel paletted or grayscale data will be returned
2 pixels/byte with the leftmost pixel in the high-order bits of the
byte, unless png_set_packing() is called. 8-bit RGB data will be stored
in RGB RGB RGB format unless png_set_filler() or png_set_add_alpha()
is called to insert filler bytes, either before or after each RGB triplet.
16-bit RGB data will be returned RRGGBB RRGGBB, with the most significant
byte of the color value first, unless png_set_scale_16() is called to
transform it to regular RGB RGB triplets, or png_set_filler() or
png_set_add alpha() is called to insert filler bytes, either before or
after each RRGGBB triplet. Similarly, 8-bit or 16-bit grayscale data can
be modified with png_set_filler(), png_set_add_alpha(), png_set_strip_16(),
or png_set_scale_16().
The following code transforms grayscale images of less than 8 to 8 bits,
changes paletted images to RGB, and adds a full alpha channel if there is
transparency information in a tRNS chunk. This is most useful on
grayscale images with bit depths of 2 or 4 or if there is a multiple-image
viewing application that wishes to treat all images in the same way.
if (color_type == PNG_COLOR_TYPE_PALETTE)
png_set_palette_to_rgb(png_ptr);
if (png_get_valid(png_ptr, info_ptr,
PNG_INFO_tRNS)) png_set_tRNS_to_alpha(png_ptr);
if (color_type == PNG_COLOR_TYPE_GRAY &&
bit_depth < 8) png_set_expand_gray_1_2_4_to_8(png_ptr);
The first two functions are actually aliases for png_set_expand(), added
in libpng version 1.0.4, with the function names expanded to improve code
readability. In some future version they may actually do different
things.
As of libpng version 1.2.9, png_set_expand_gray_1_2_4_to_8() was
added. It expands the sample depth without changing tRNS to alpha.
As of libpng version 1.5.2, png_set_expand_16() was added. It behaves as
png_set_expand(); however, the resultant channels have 16 bits rather than 8.
Use this when the output color or gray channels are made linear to avoid fairly
severe accuracy loss.
if (bit_depth < 16)
png_set_expand_16(png_ptr);
PNG can have files with 16 bits per channel. If you only can handle
8 bits per channel, this will strip the pixels down to 8-bit.
if (bit_depth == 16)
#if PNG_LIBPNG_VER >= 10504
png_set_scale_16(png_ptr);
#else
png_set_strip_16(png_ptr);
#endif
(The more accurate "png_set_scale_16()" API became available in libpng version
1.5.4).
If you need to process the alpha channel on the image separately from the image
data (for example if you convert it to a bitmap mask) it is possible to have
libpng strip the channel leaving just RGB or gray data:
if (color_type & PNG_COLOR_MASK_ALPHA)
png_set_strip_alpha(png_ptr);
If you strip the alpha channel you need to find some other way of dealing with
the information. If, instead, you want to convert the image to an opaque
version with no alpha channel use png_set_background; see below.
As of libpng version 1.5.2, almost all useful expansions are supported, the
major ommissions are conversion of grayscale to indexed images (which can be
done trivially in the application) and conversion of indexed to grayscale (which
can be done by a trivial manipulation of the palette.)
In the following table, the 01 means grayscale with depth<8, 31 means
indexed with depth<8, other numerals represent the color type, "T" means
the tRNS chunk is present, A means an alpha channel is present, and O
means tRNS or alpha is present but all pixels in the image are opaque.
FROM 01 31 0 0T 0O 2 2T 2O 3 3T 3O 4A 4O 6A 6O
src/Source/LibPNG/libpng.3 view on Meta::CPAN
3O [Qt] p [Qt][Q] [Q] Qt Qt Qt t t + [Qt][Qt] Qt Qt
4A lA G A T T GA GT GT GA GT GT + BA G GBA
4O lA GBA A T T GA GT GT GA GT GT BA + GBA G
6A CA PA CA C C A T tT PA P P C CBA + BA
6O CA PBA CA C C A tT T PA P P CBA C BA +
Within the matrix,
"+" identifies entries where 'from' and 'to' are the same.
"-" means the transformation is not supported.
"." means nothing is necessary (a tRNS chunk can just be ignored).
"t" means the transformation is obtained by png_set_tRNS.
"A" means the transformation is obtained by png_set_add_alpha().
"X" means the transformation is obtained by png_set_expand().
"1" means the transformation is obtained by
png_set_expand_gray_1_2_4_to_8() (and by png_set_expand()
if there is no transparency in the original or the final
format).
"C" means the transformation is obtained by png_set_gray_to_rgb().
"G" means the transformation is obtained by png_set_rgb_to_gray().
"P" means the transformation is obtained by
png_set_expand_palette_to_rgb().
"p" means the transformation is obtained by png_set_packing().
"Q" means the transformation is obtained by png_set_quantize().
"T" means the transformation is obtained by
png_set_tRNS_to_alpha().
"B" means the transformation is obtained by
png_set_background(), or png_strip_alpha().
When an entry has multiple transforms listed all are required to cause the
right overall transformation. When two transforms are separated by a comma
either will do the job. When transforms are enclosed in [] the transform should
do the job but this is currently unimplemented - a different format will result
if the suggested transformations are used.
In PNG files, the alpha channel in an image
is the level of opacity. If you need the alpha channel in an image to
be the level of transparency instead of opacity, you can invert the
alpha channel (or the tRNS chunk data) after it's read, so that 0 is
fully opaque and 255 (in 8-bit or paletted images) or 65535 (in 16-bit
images) is fully transparent, with
png_set_invert_alpha(png_ptr);
PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
they can, resulting in, for example, 8 pixels per byte for 1 bit
files. This code expands to 1 pixel per byte without changing the
values of the pixels:
if (bit_depth < 8)
png_set_packing(png_ptr);
PNG files have possible bit depths of 1, 2, 4, 8, and 16. All pixels
stored in a PNG image have been "scaled" or "shifted" up to the next
higher possible bit depth (e.g. from 5 bits/sample in the range [0,31]
to 8 bits/sample in the range [0, 255]). However, it is also possible
to convert the PNG pixel data back to the original bit depth of the
image. This call reduces the pixels back down to the original bit depth:
png_color_8p sig_bit;
if (png_get_sBIT(png_ptr, info_ptr, &sig_bit))
png_set_shift(png_ptr, sig_bit);
PNG files store 3-color pixels in red, green, blue order. This code
changes the storage of the pixels to blue, green, red:
if (color_type == PNG_COLOR_TYPE_RGB ||
color_type == PNG_COLOR_TYPE_RGB_ALPHA)
png_set_bgr(png_ptr);
PNG files store RGB pixels packed into 3 or 6 bytes. This code expands them
into 4 or 8 bytes for windowing systems that need them in this format:
if (color_type == PNG_COLOR_TYPE_RGB)
png_set_filler(png_ptr, filler, PNG_FILLER_BEFORE);
where "filler" is the 8 or 16-bit number to fill with, and the location is
either PNG_FILLER_BEFORE or PNG_FILLER_AFTER, depending upon whether
you want the filler before the RGB or after. This transformation
does not affect images that already have full alpha channels. To add an
opaque alpha channel, use filler=0xff or 0xffff and PNG_FILLER_AFTER which
will generate RGBA pixels.
Note that png_set_filler() does not change the color type. If you want
to do that, you can add a true alpha channel with
if (color_type == PNG_COLOR_TYPE_RGB ||
color_type == PNG_COLOR_TYPE_GRAY)
png_set_add_alpha(png_ptr, filler, PNG_FILLER_AFTER);
where "filler" contains the alpha value to assign to each pixel.
This function was added in libpng-1.2.7.
If you are reading an image with an alpha channel, and you need the
data as ARGB instead of the normal PNG format RGBA:
if (color_type == PNG_COLOR_TYPE_RGB_ALPHA)
png_set_swap_alpha(png_ptr);
For some uses, you may want a grayscale image to be represented as
RGB. This code will do that conversion:
if (color_type == PNG_COLOR_TYPE_GRAY ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
png_set_gray_to_rgb(png_ptr);
Conversely, you can convert an RGB or RGBA image to grayscale or grayscale
with alpha.
if (color_type == PNG_COLOR_TYPE_RGB ||
color_type == PNG_COLOR_TYPE_RGB_ALPHA)
png_set_rgb_to_gray(png_ptr, error_action,
double red_weight, double green_weight);
error_action = 1: silently do the conversion
error_action = 2: issue a warning if the original
image has any pixel where
red != green or red != blue
error_action = 3: issue an error and abort the
conversion if the original
src/Source/LibPNG/libpng.3 view on Meta::CPAN
red_weight: weight of red component
green_weight: weight of green component
If either weight is negative, default
weights are used.
In the corresponding fixed point API the red_weight and green_weight values are
simply scaled by 100,000:
png_set_rgb_to_gray(png_ptr, error_action,
png_fixed_point red_weight,
png_fixed_point green_weight);
If you have set error_action = 1 or 2, you can
later check whether the image really was gray, after processing
the image rows, with the png_get_rgb_to_gray_status(png_ptr) function.
It will return a png_byte that is zero if the image was gray or
1 if there were any non-gray pixels. Background and sBIT data
will be silently converted to grayscale, using the green channel
data for sBIT, regardless of the error_action setting.
The default values come from the PNG file cHRM chunk if present; otherwise, the
defaults correspond to the ITU-R recommendation 709, and also the sRGB color
space, as recommended in the Charles Poynton's Colour FAQ,
<http://www.poynton.com/>, in section 9:
<http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html#RTFToC9>
Y = 0.2126 * R + 0.7152 * G + 0.0722 * B
Previous versions of this document, 1998 through 2002, recommended a slightly
different formula:
Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
Libpng uses an integer approximation:
Y = (6968 * R + 23434 * G + 2366 * B)/32768
The calculation is done in a linear colorspace, if the image gamma
can be determined.
The png_set_background() function has been described already; it tells libpng to
composite images with alpha or simple transparency against the supplied
background color. For compatibility with versions of libpng earlier than
libpng-1.5.4 it is recommended that you call the function after reading the file
header, even if you don't want to use the color in a bKGD chunk, if one exists.
If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid),
you may use this color, or supply another color more suitable for
the current display (e.g., the background color from a web page). You
need to tell libpng how the color is represented, both the format of the
component values in the color (the number of bits) and the gamma encoding of the
color. The function takes two arguments, background_gamma_mode and need_expand
to convey this information; however, only two combinations are likely to be
useful:
png_color_16 my_background;
png_color_16p image_background;
if (png_get_bKGD(png_ptr, info_ptr, &image_background))
png_set_background(png_ptr, image_background,
PNG_BACKGROUND_GAMMA_FILE, 1/*needs to be expanded*/, 1);
else
png_set_background(png_ptr, &my_background,
PNG_BACKGROUND_GAMMA_SCREEN, 0/*do not expand*/, 1);
The second call was described above - my_background is in the format of the
final, display, output produced by libpng. Because you now know the format of
the PNG it is possible to avoid the need to choose either 8-bit or 16-bit
output and to retain palette images (the palette colors will be modified
appropriately and the tRNS chunk removed.) However, if you are doing this,
take great care not to ask for transformations without checking first that
they apply!
In the first call the background color has the original bit depth and color type
of the PNG file. So, for palette images the color is supplied as a palette
index and for low bit greyscale images the color is a reduced bit value in
image_background->gray.
If you didn't call png_set_gamma() before reading the file header, for example
if you need your code to remain compatible with older versions of libpng prior
to libpng-1.5.4, this is the place to call it.
Do not call it if you called png_set_alpha_mode(); doing so will damage the
settings put in place by png_set_alpha_mode(). (If png_set_alpha_mode() is
supported then you can certainly do png_set_gamma() before reading the PNG
header.)
This API unconditionally sets the screen and file gamma values, so it will
override the value in the PNG file unless it is called before the PNG file
reading starts. For this reason you must always call it with the PNG file
value when you call it in this position:
if (png_get_gAMA(png_ptr, info_ptr, &file_gamma))
png_set_gamma(png_ptr, screen_gamma, file_gamma);
else
png_set_gamma(png_ptr, screen_gamma, 0.45455);
If you need to reduce an RGB file to a paletted file, or if a paletted
file has more entries then will fit on your screen, png_set_quantize()
will do that. Note that this is a simple match quantization that merely
finds the closest color available. This should work fairly well with
optimized palettes, but fairly badly with linear color cubes. If you
pass a palette that is larger than maximum_colors, the file will
reduce the number of colors in the palette so it will fit into
maximum_colors. If there is a histogram, libpng will use it to make
more intelligent choices when reducing the palette. If there is no
histogram, it may not do as good a job.
if (color_type & PNG_COLOR_MASK_COLOR)
{
if (png_get_valid(png_ptr, info_ptr,
PNG_INFO_PLTE))
{
png_uint_16p histogram = NULL;
png_get_hIST(png_ptr, info_ptr,
&histogram);
png_set_quantize(png_ptr, palette, num_palette,
max_screen_colors, histogram, 1);
}
else
{
png_color std_color_cube[MAX_SCREEN_COLORS] =
{ ... colors ... };
png_set_quantize(png_ptr, std_color_cube,
MAX_SCREEN_COLORS, MAX_SCREEN_COLORS,
NULL,0);
}
}
PNG files describe monochrome as black being zero and white being one.
The following code will reverse this (make black be one and white be
zero):
if (bit_depth == 1 && color_type == PNG_COLOR_TYPE_GRAY)
png_set_invert_mono(png_ptr);
This function can also be used to invert grayscale and gray-alpha images:
if (color_type == PNG_COLOR_TYPE_GRAY ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
png_set_invert_mono(png_ptr);
PNG files store 16-bit pixels in network byte order (big-endian,
ie. most significant bits first). This code changes the storage to the
other way (little-endian, i.e. least significant bits first, the
way PCs store them):
if (bit_depth == 16)
png_set_swap(png_ptr);
If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
need to change the order the pixels are packed into bytes, you can use:
if (bit_depth < 8)
png_set_packswap(png_ptr);
Finally, you can write your own transformation function if none of
the existing ones meets your needs. This is done by setting a callback
with
png_set_read_user_transform_fn(png_ptr,
read_transform_fn);
You must supply the function
void read_transform_fn(png_structp png_ptr, png_row_infop
row_info, png_bytep data)
See pngtest.c for a working example. Your function will be called
after all of the other transformations have been processed. Take care with
interlaced images if you do the interlace yourself - the width of the row is the
width in 'row_info', not the overall image width.
If supported, libpng provides two information routines that you can use to find
where you are in processing the image:
png_get_current_pass_number(png_structp png_ptr);
png_get_current_row_number(png_structp png_ptr);
Don't try using these outside a transform callback - firstly they are only
supported if user transforms are supported, secondly they may well return
unexpected results unless the row is actually being processed at the moment they
are called.
With interlaced
images the value returned is the row in the input sub-image image. Use
PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass).
The discussion of interlace handling above contains more information on how to
use these values.
You can also set up a pointer to a user structure for use by your
callback function, and you can inform libpng that your transform
function will change the number of channels or bit depth with the
function
png_set_user_transform_info(png_ptr, user_ptr,
user_depth, user_channels);
The user's application, not libpng, is responsible for allocating and
freeing any memory required for the user structure.
You can retrieve the pointer via the function
png_get_user_transform_ptr(). For example:
voidp read_user_transform_ptr =
png_get_user_transform_ptr(png_ptr);
The last thing to handle is interlacing; this is covered in detail below,
but you must call the function here if you want libpng to handle expansion
of the interlaced image.
number_of_passes = png_set_interlace_handling(png_ptr);
After setting the transformations, libpng can update your png_info
structure to reflect any transformations you've requested with this
call.
png_read_update_info(png_ptr, info_ptr);
This is most useful to update the info structure's rowbytes
field so you can use it to allocate your image memory. This function
will also update your palette with the correct screen_gamma and
background if these have been given with the calls above. You may
only call png_read_update_info() once with a particular info_ptr.
After you call png_read_update_info(), you can allocate any
memory you need to hold the image. The row data is simply
raw byte data for all forms of images. As the actual allocation
varies among applications, no example will be given. If you
are allocating one large chunk, you will need to build an
array of pointers to each row, as it will be needed for some
of the functions below.
Remember: Before you call png_read_update_info(), the png_get_*()
functions return the values corresponding to the original PNG image.
After you call png_read_update_info the values refer to the image
that libpng will output. Consequently you must call all the png_set_
functions before you call png_read_update_info(). This is particularly
important for png_set_interlace_handling() - if you are going to call
png_read_update_info() you must call png_set_interlace_handling() before
it unless you want to receive interlaced output.
.SS Reading image data
After you've allocated memory, you can read the image data.
The simplest way to do this is in one function call. If you are
allocating enough memory to hold the whole image, you can just
call png_read_image() and libpng will read in all the image data
and put it in the memory area supplied. You will need to pass in
an array of pointers to each row.
This function automatically handles interlacing, so you don't
need to call png_set_interlace_handling() (unless you call
png_read_update_info()) or call this function multiple times, or any
of that other stuff necessary with png_read_rows().
png_read_image(png_ptr, row_pointers);
where row_pointers is:
png_bytep row_pointers[height];
You can point to void or char or whatever you use for pixels.
If you don't want to read in the whole image at once, you can
use png_read_rows() instead. If there is no interlacing (check
interlace_type == PNG_INTERLACE_NONE), this is simple:
png_read_rows(png_ptr, row_pointers, NULL,
number_of_rows);
where row_pointers is the same as in the png_read_image() call.
If you are doing this just one row at a time, you can do this with
a single row_pointer instead of an array of row_pointers:
png_bytep row_pointer = row;
png_read_row(png_ptr, row_pointer, NULL);
If the file is interlaced (interlace_type != 0 in the IHDR chunk), things
get somewhat harder. The only current (PNG Specification version 1.2)
interlacing type for PNG is (interlace_type == PNG_INTERLACE_ADAM7);
a somewhat complicated 2D interlace scheme, known as Adam7, that
breaks down an image into seven smaller images of varying size, based
on an 8x8 grid. This number is defined (from libpng 1.5) as
PNG_INTERLACE_ADAM7_PASSES in png.h
libpng can fill out those images or it can give them to you "as is".
It is almost always better to have libpng handle the interlacing for you.
If you want the images filled out, there are two ways to do that. The one
mentioned in the PNG specification is to expand each pixel to cover
those pixels that have not been read yet (the "rectangle" method).
This results in a blocky image for the first pass, which gradually
smooths out as more pixels are read. The other method is the "sparkle"
method, where pixels are drawn only in their final locations, with the
rest of the image remaining whatever colors they were initialized to
before the start of the read. The first method usually looks better,
but tends to be slower, as there are more pixels to put in the rows.
If, as is likely, you want libpng to expand the images, call this before
calling png_start_read_image() or png_read_update_info():
if (interlace_type == PNG_INTERLACE_ADAM7)
number_of_passes
= png_set_interlace_handling(png_ptr);
This will return the number of passes needed. Currently, this is seven,
but may change if another interlace type is added. This function can be
called even if the file is not interlaced, where it will return one pass.
You then need to read the whole image 'number_of_passes' times. Each time
will distribute the pixels from the current pass to the correct place in
the output image, so you need to supply the same rows to png_read_rows in
each pass.
If you are not going to display the image after each pass, but are
going to wait until the entire image is read in, use the sparkle
effect. This effect is faster and the end result of either method
is exactly the same. If you are planning on displaying the image
after each pass, the "rectangle" effect is generally considered the
better looking one.
If you only want the "sparkle" effect, just call png_read_rows() as
normal, with the third parameter NULL. Make sure you make pass over
the image number_of_passes times, and you don't change the data in the
rows between calls. You can change the locations of the data, just
not the data. Each pass only writes the pixels appropriate for that
pass, and assumes the data from previous passes is still valid.
png_read_rows(png_ptr, row_pointers, NULL,
number_of_rows);
If you only want the first effect (the rectangles), do the same as
before except pass the row buffer in the third parameter, and leave
the second parameter NULL.
png_read_rows(png_ptr, NULL, row_pointers,
number_of_rows);
If you don't want libpng to handle the interlacing details, just call
png_read_rows() PNG_INTERLACE_ADAM7_PASSES times to read in all the images.
Each of the images is a valid image by itself; however, you will almost
certainly need to distribute the pixels from each sub-image to the
correct place. This is where everything gets very tricky.
If you want to retrieve the separate images you must pass the correct
number of rows to each successive call of png_read_rows(). The calculation
gets pretty complicated for small images, where some sub-images may
not even exist because either their width or height ends up zero.
libpng provides two macros to help you in 1.5 and later versions:
png_uint_32 width = PNG_PASS_COLS(image_width, pass_number);
png_uint_32 height = PNG_PASS_ROWS(image_height, pass_number);
Respectively these tell you the width and height of the sub-image
corresponding to the numbered pass. 'pass' is in in the range 0 to 6 -
this can be confusing because the specification refers to the same passes
as 1 to 7! Be careful, you must check both the width and height before
calling png_read_rows() and not call it for that pass if either is zero.
You can, of course, read each sub-image row by row. If you want to
produce optimal code to make a pixel-by-pixel transformation of an
interlaced image this is the best approach; read each row of each pass,
transform it, and write it out to a new interlaced image.
If you want to de-interlace the image yourself libpng provides further
macros to help that tell you where to place the pixels in the output image.
Because the interlacing scheme is rectangular - sub-image pixels are always
arranged on a rectangular grid - all you need to know for each pass is the
starting column and row in the output image of the first pixel plus the
spacing between each pixel. As of libpng 1.5 there are four macros to
retrieve this information:
png_uint_32 x = PNG_PASS_START_COL(pass);
png_uint_32 y = PNG_PASS_START_ROW(pass);
png_uint_32 xStep = 1U << PNG_PASS_COL_SHIFT(pass);
png_uint_32 yStep = 1U << PNG_PASS_ROW_SHIFT(pass);
These allow you to write the obvious loop:
png_uint_32 input_y = 0;
png_uint_32 output_y = PNG_PASS_START_ROW(pass);
while (output_y < output_image_height)
{
png_uint_32 input_x = 0;
png_uint_32 output_x = PNG_PASS_START_COL(pass);
while (output_x < output_image_width)
{
image[output_y][output_x] =
subimage[pass][input_y][input_x++];
output_x += xStep;
}
++input_y;
output_y += yStep;
}
Notice that the steps between successive output rows and columns are
returned as shifts. This is possible because the pixels in the subimages
are always a power of 2 apart - 1, 2, 4 or 8 pixels - in the original
image. In practice you may need to directly calculate the output coordinate
given an input coordinate. libpng provides two further macros for this
purpose:
png_uint_32 output_x = PNG_COL_FROM_PASS_COL(input_x, pass);
png_uint_32 output_y = PNG_ROW_FROM_PASS_ROW(input_y, pass);
Finally a pair of macros are provided to tell you if a particular image
row or column appears in a given pass:
int col_in_pass = PNG_COL_IN_INTERLACE_PASS(output_x, pass);
int row_in_pass = PNG_ROW_IN_INTERLACE_PASS(output_y, pass);
Bear in mind that you will probably also need to check the width and height
of the pass in addition to the above to be sure the pass even exists!
With any luck you are convinced by now that you don't want to do your own
interlace handling. In reality normally the only good reason for doing this
is if you are processing PNG files on a pixel-by-pixel basis and don't want
to load the whole file into memory when it is interlaced.
libpng includes a test program, pngvalid, that illustrates reading and
writing of interlaced images. If you can't get interlacing to work in your
code and don't want to leave it to libpng (the recommended approach), see
how pngvalid.c does it.
.SS Finishing a sequential read
After you are finished reading the image through the
low-level interface, you can finish reading the file.
If you want to use a different crc action for handling CRC errors in
chunks after the image data, you can call png_set_crc_action()
again at this point.
If you are interested in comments or time, which may be stored either
before or after the image data, you should pass the separate png_info
struct if you want to keep the comments from before and after the image
separate.
png_infop end_info = png_create_info_struct(png_ptr);
if (!end_info)
{
png_destroy_read_struct(&png_ptr, &info_ptr,
(png_infopp)NULL);
return (ERROR);
}
png_read_end(png_ptr, end_info);
If you are not interested, you should still call png_read_end()
but you can pass NULL, avoiding the need to create an end_info structure.
If you do this, libpng will not process any chunks after IDAT other than
skipping over them and perhaps (depending on whether you have called
png_set_crc_action) checking their CRCs while looking for the IEND chunk.
png_read_end(png_ptr, (png_infop)NULL);
If you don't call png_read_end(), then your file pointer will be
left pointing to the first chunk after the last IDAT, which is probably
not what you want if you expect to read something beyond the end of
the PNG datastream.
When you are done, you can free all memory allocated by libpng like this:
png_destroy_read_struct(&png_ptr, &info_ptr,
&end_info);
or, if you didn't create an end_info structure,
png_destroy_read_struct(&png_ptr, &info_ptr,
(png_infopp)NULL);
It is also possible to individually free the info_ptr members that
point to libpng-allocated storage with the following function:
png_free_data(png_ptr, info_ptr, mask, seq)
mask - identifies data to be freed, a mask
containing the bitwise OR of one or
more of
PNG_FREE_PLTE, PNG_FREE_TRNS,
PNG_FREE_HIST, PNG_FREE_ICCP,
PNG_FREE_PCAL, PNG_FREE_ROWS,
PNG_FREE_SCAL, PNG_FREE_SPLT,
PNG_FREE_TEXT, PNG_FREE_UNKN,
or simply PNG_FREE_ALL
seq - sequence number of item to be freed
(\-1 for all items)
This function may be safely called when the relevant storage has
already been freed, or has not yet been allocated, or was allocated
by the user and not by libpng, and will in those cases do nothing.
The "seq" parameter is ignored if only one item of the selected data
type, such as PLTE, is allowed. If "seq" is not \-1, and multiple items
are allowed for the data type identified in the mask, such as text or
sPLT, only the n'th item in the structure is freed, where n is "seq".
The default behavior is only to free data that was allocated internally
by libpng. This can be changed, so that libpng will not free the data,
or so that it will free data that was allocated by the user with png_malloc()
or png_calloc() and passed in via a png_set_*() function, with
png_data_freer(png_ptr, info_ptr, freer, mask)
freer - one of
PNG_DESTROY_WILL_FREE_DATA
PNG_SET_WILL_FREE_DATA
PNG_USER_WILL_FREE_DATA
mask - which data elements are affected
same choices as in png_free_data()
This function only affects data that has already been allocated.
You can call this function after reading the PNG data but before calling
any png_set_*() functions, to control whether the user or the png_set_*()
function is responsible for freeing any existing data that might be present,
and again after the png_set_*() functions to control whether the user
or png_destroy_*() is supposed to free the data. When the user assumes
responsibility for libpng-allocated data, the application must use
png_free() to free it, and when the user transfers responsibility to libpng
for data that the user has allocated, the user must have used png_malloc()
or png_calloc() to allocate it.
If you allocated your row_pointers in a single block, as suggested above in
the description of the high level read interface, you must not transfer
responsibility for freeing it to the png_set_rows or png_read_destroy function,
because they would also try to free the individual row_pointers[i].
If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
separately, do not transfer responsibility for freeing text_ptr to libpng,
because when libpng fills a png_text structure it combines these members with
the key member, and png_free_data() will free only text_ptr.key. Similarly,
if you transfer responsibility for free'ing text_ptr from libpng to your
application, your application must not separately free those members.
The png_free_data() function will turn off the "valid" flag for anything
it frees. If you need to turn the flag off for a chunk that was freed by
your application instead of by libpng, you can use
png_set_invalid(png_ptr, info_ptr, mask);
mask - identifies the chunks to be made invalid,
containing the bitwise OR of one or
more of
PNG_INFO_gAMA, PNG_INFO_sBIT,
PNG_INFO_cHRM, PNG_INFO_PLTE,
PNG_INFO_tRNS, PNG_INFO_bKGD,
PNG_INFO_hIST, PNG_INFO_pHYs,
PNG_INFO_oFFs, PNG_INFO_tIME,
PNG_INFO_pCAL, PNG_INFO_sRGB,
PNG_INFO_iCCP, PNG_INFO_sPLT,
PNG_INFO_sCAL, PNG_INFO_IDAT
For a more compact example of reading a PNG image, see the file example.c.
.SS Reading PNG files progressively
The progressive reader is slightly different from the non-progressive
reader. Instead of calling png_read_info(), png_read_rows(), and
png_read_end(), you make one call to png_process_data(), which calls
callbacks when it has the info, a row, or the end of the image. You
set up these callbacks with png_set_progressive_read_fn(). You don't
have to worry about the input/output functions of libpng, as you are
giving the library the data directly in png_process_data(). I will
assume that you have read the section on reading PNG files above,
so I will only highlight the differences (although I will show
all of the code).
png_structp png_ptr;
png_infop info_ptr;
/* An example code fragment of how you would
initialize the progressive reader in your
application. */
int
initialize_png_reader()
{
png_ptr = png_create_read_struct
(PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
user_error_fn, user_warning_fn);
if (!png_ptr)
return (ERROR);
info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
{
png_destroy_read_struct(&png_ptr,
(png_infopp)NULL, (png_infopp)NULL);
return (ERROR);
}
if (setjmp(png_jmpbuf(png_ptr)))
{
png_destroy_read_struct(&png_ptr, &info_ptr,
(png_infopp)NULL);
return (ERROR);
}
/* This one's new. You can provide functions
to be called when the header info is valid,
when each row is completed, and when the image
is finished. If you aren't using all functions,
you can specify NULL parameters. Even when all
three functions are NULL, you need to call
png_set_progressive_read_fn(). You can use
any struct as the user_ptr (cast to a void pointer
for the function call), and retrieve the pointer
from inside the callbacks using the function
png_get_progressive_ptr(png_ptr);
which will return a void pointer, which you have
to cast appropriately.
*/
png_set_progressive_read_fn(png_ptr, (void *)user_ptr,
info_callback, row_callback, end_callback);
return 0;
}
/* A code fragment that you call as you receive blocks
of data */
int
process_data(png_bytep buffer, png_uint_32 length)
{
if (setjmp(png_jmpbuf(png_ptr)))
{
png_destroy_read_struct(&png_ptr, &info_ptr,
(png_infopp)NULL);
return (ERROR);
}
/* This one's new also. Simply give it a chunk
of data from the file stream (in order, of
course). On machines with segmented memory
models machines, don't give it any more than
64K. The library seems to run fine with sizes
of 4K. Although you can give it much less if
necessary (I assume you can give it chunks of
1 byte, I haven't tried less then 256 bytes
yet). When this function returns, you may
want to display any rows that were generated
in the row callback if you don't already do
so there.
*/
png_process_data(png_ptr, info_ptr, buffer, length);
/* At this point you can call png_process_data_skip if
you want to handle data the library will skip yourself;
it simply returns the number of bytes to skip (and stops
libpng skipping that number of bytes on the next
png_process_data call).
return 0;
}
/* This function is called (as set by
png_set_progressive_read_fn() above) when enough data
has been supplied so all of the header has been
read.
*/
void
info_callback(png_structp png_ptr, png_infop info)
{
/* Do any setup here, including setting any of
the transformations mentioned in the Reading
PNG files section. For now, you _must_ call
either png_start_read_image() or
png_read_update_info() after all the
transformations are set (even if you don't set
any). You may start getting rows before
png_process_data() returns, so this is your
last chance to prepare for that.
This is where you turn on interlace handling,
assuming you don't want to do it yourself.
If you need to you can stop the processing of
your original input data at this point by calling
png_process_data_pause. This returns the number
of unprocessed bytes from the last png_process_data
call - it is up to you to ensure that the next call
sees these bytes again. If you don't want to bother
with this you can get libpng to cache the unread
bytes by setting the 'save' parameter (see png.h) but
then libpng will have to copy the data internally.
*/
}
/* This function is called when each row of image
data is complete */
void
row_callback(png_structp png_ptr, png_bytep new_row,
png_uint_32 row_num, int pass)
{
/* If the image is interlaced, and you turned
on the interlace handler, this function will
be called for every row in every pass. Some
of these rows will not be changed from the
previous pass. When the row is not changed,
the new_row variable will be NULL. The rows
and passes are called in order, so you don't
really need the row_num and pass, but I'm
supplying them because it may make your life
easier.
If you did not turn on interlace handling then
the callback is called for each row of each
sub-image when the image is interlaced. In this
case 'row_num' is the row in the sub-image, not
the row in the output image as it is in all other
cases.
For the non-NULL rows of interlaced images when
you have switched on libpng interlace handling,
you must call png_progressive_combine_row()
passing in the row and the old row. You can
call this function for NULL rows (it will just
return) and for non-interlaced images (it just
does the memcpy for you) if it will make the
code easier. Thus, you can just do this for
all cases if you switch on interlace handling;
*/
png_progressive_combine_row(png_ptr, old_row,
new_row);
/* where old_row is what was displayed
previously for the row. Note that the first
pass (pass == 0, really) will completely cover
the old row, so the rows do not have to be
initialized. After the first pass (and only
for interlaced images), you will have to pass
the current row, and the function will combine
the old row and the new row.
You can also call png_process_data_pause in this
callback - see above.
*/
}
void
end_callback(png_structp png_ptr, png_infop info)
{
/* This function is called after the whole image
has been read, including any chunks after the
image (up to and including the IEND). You
will usually have the same info chunk as you
had in the header, although some data may have
been added to the comments and time fields.
Most people won't do much here, perhaps setting
a flag that marks the image as finished.
src/Source/LibPNG/libpng.3 view on Meta::CPAN
.SH IV. Writing
Much of this is very similar to reading. However, everything of
importance is repeated here, so you won't have to constantly look
back up in the reading section to understand writing.
.SS Setup
You will want to do the I/O initialization before you get into libpng,
so if it doesn't work, you don't have anything to undo. If you are not
using the standard I/O functions, you will need to replace them with
custom writing functions. See the discussion under Customizing libpng.
FILE *fp = fopen(file_name, "wb");
if (!fp)
return (ERROR);
Next, png_struct and png_info need to be allocated and initialized.
As these can be both relatively large, you may not want to store these
on the stack, unless you have stack space to spare. Of course, you
will want to check if they return NULL. If you are also reading,
you won't want to name your read structure and your write structure
both "png_ptr"; you can call them anything you like, such as
"read_ptr" and "write_ptr". Look at pngtest.c, for example.
png_structp png_ptr = png_create_write_struct
(PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
user_error_fn, user_warning_fn);
if (!png_ptr)
return (ERROR);
png_infop info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
{
png_destroy_write_struct(&png_ptr,
(png_infopp)NULL);
return (ERROR);
}
If you want to use your own memory allocation routines,
define PNG_USER_MEM_SUPPORTED and use
png_create_write_struct_2() instead of png_create_write_struct():
png_structp png_ptr = png_create_write_struct_2
(PNG_LIBPNG_VER_STRING, (png_voidp)user_error_ptr,
user_error_fn, user_warning_fn, (png_voidp)
user_mem_ptr, user_malloc_fn, user_free_fn);
After you have these structures, you will need to set up the
error handling. When libpng encounters an error, it expects to
longjmp() back to your routine. Therefore, you will need to call
setjmp() and pass the png_jmpbuf(png_ptr). If you
write the file from different routines, you will need to update
the png_jmpbuf(png_ptr) every time you enter a new routine that will
call a png_*() function. See your documentation of setjmp/longjmp
for your compiler for more information on setjmp/longjmp. See
the discussion on libpng error handling in the Customizing Libpng
section below for more information on the libpng error handling.
if (setjmp(png_jmpbuf(png_ptr)))
{
png_destroy_write_struct(&png_ptr, &info_ptr);
fclose(fp);
return (ERROR);
}
...
return;
If you would rather avoid the complexity of setjmp/longjmp issues,
you can compile libpng with PNG_NO_SETJMP, in which case
errors will result in a call to PNG_ABORT() which defaults to abort().
You can #define PNG_ABORT() to a function that does something
more useful than abort(), as long as your function does not
return.
Checking for invalid palette index on write was added at libpng
1.5.10. If a pixel contains an invalid (out-of-range) index libpng issues
a benign error. This is enabled by default because this condition is an
error according to the PNG specification, Clause 11.3.2, but the error can
be ignored in each png_ptr with
png_set_check_for_invalid_index(png_ptr, 0);
If the error is ignored, or if png_benign_error() treats it as a warning,
any invalid pixels are written as-is by the encoder, resulting in an
invalid PNG datastream as output. In this case the application is
responsible for ensuring that the pixel indexes are in range when it writes
a PLTE chunk with fewer entries than the bit depth would allow.
Now you need to set up the output code. The default for libpng is to
use the C function fwrite(). If you use this, you will need to pass a
valid FILE * in the function png_init_io(). Be sure that the file is
opened in binary mode. Again, if you wish to handle writing data in
another way, see the discussion on libpng I/O handling in the Customizing
Libpng section below.
png_init_io(png_ptr, fp);
If you are embedding your PNG into a datastream such as MNG, and don't
want libpng to write the 8-byte signature, or if you have already
written the signature in your application, use
png_set_sig_bytes(png_ptr, 8);
to inform libpng that it should not write a signature.
.SS Write callbacks
At this point, you can set up a callback function that will be
called after each row has been written, which you can use to control
a progress meter or the like. It's demonstrated in pngtest.c.
You must supply a function
void write_row_callback(png_structp png_ptr, png_uint_32 row,
int pass);
{
/* put your code here */
}
(You can give it another name that you like instead of "write_row_callback")
To inform libpng about your function, use
png_set_write_status_fn(png_ptr, write_row_callback);
When this function is called the row has already been completely processed and
it has also been written out. The 'row' and 'pass' refer to the next row to be
handled. For the
non-interlaced case the row that was just handled is simply one less than the
passed in row number, and pass will always be 0. For the interlaced case the
same applies unless the row value is 0, in which case the row just handled was
the last one from one of the preceding passes. Because interlacing may skip a
pass you cannot be sure that the preceding pass is just 'pass\-1', if you really
need to know what the last pass is record (row,pass) from the callback and use
src/Source/LibPNG/libpng.3 view on Meta::CPAN
As with the user transform you can find the output row using the
PNG_ROW_FROM_PASS_ROW macro.
You now have the option of modifying how the compression library will
run. The following functions are mainly for testing, but may be useful
in some cases, like if you need to write PNG files extremely fast and
are willing to give up some compression, or if you want to get the
maximum possible compression at the expense of slower writing. If you
have no special needs in this area, let the library do what it wants by
not calling this function at all, as it has been tuned to deliver a good
speed/compression ratio. The second parameter to png_set_filter() is
the filter method, for which the only valid values are 0 (as of the
July 1999 PNG specification, version 1.2) or 64 (if you are writing
a PNG datastream that is to be embedded in a MNG datastream). The third
parameter is a flag that indicates which filter type(s) are to be tested
for each scanline. See the PNG specification for details on the specific
filter types.
/* turn on or off filtering, and/or choose
specific filters. You can use either a single
PNG_FILTER_VALUE_NAME or the bitwise OR of one
or more PNG_FILTER_NAME masks.
*/
png_set_filter(png_ptr, 0,
PNG_FILTER_NONE | PNG_FILTER_VALUE_NONE |
PNG_FILTER_SUB | PNG_FILTER_VALUE_SUB |
PNG_FILTER_UP | PNG_FILTER_VALUE_UP |
PNG_FILTER_AVG | PNG_FILTER_VALUE_AVG |
PNG_FILTER_PAETH | PNG_FILTER_VALUE_PAETH|
PNG_ALL_FILTERS);
If an application wants to start and stop using particular filters during
compression, it should start out with all of the filters (to ensure that
the previous row of pixels will be stored in case it's needed later),
and then add and remove them after the start of compression.
If you are writing a PNG datastream that is to be embedded in a MNG
datastream, the second parameter can be either 0 or 64.
The png_set_compression_*() functions interface to the zlib compression
library, and should mostly be ignored unless you really know what you are
doing. The only generally useful call is png_set_compression_level()
which changes how much time zlib spends on trying to compress the image
data. See the Compression Library (zlib.h and algorithm.txt, distributed
with zlib) for details on the compression levels.
#include zlib.h
/* Set the zlib compression level */
png_set_compression_level(png_ptr,
Z_BEST_COMPRESSION);
/* Set other zlib parameters for compressing IDAT */
png_set_compression_mem_level(png_ptr, 8);
png_set_compression_strategy(png_ptr,
Z_DEFAULT_STRATEGY);
png_set_compression_window_bits(png_ptr, 15);
png_set_compression_method(png_ptr, 8);
png_set_compression_buffer_size(png_ptr, 8192)
/* Set zlib parameters for text compression
* If you don't call these, the parameters
* fall back on those defined for IDAT chunks
*/
png_set_text_compression_mem_level(png_ptr, 8);
png_set_text_compression_strategy(png_ptr,
Z_DEFAULT_STRATEGY);
png_set_text_compression_window_bits(png_ptr, 15);
png_set_text_compression_method(png_ptr, 8);
.SS Setting the contents of info for output
You now need to fill in the png_info structure with all the data you
wish to write before the actual image. Note that the only thing you
are allowed to write after the image is the text chunks and the time
chunk (as of PNG Specification 1.2, anyway). See png_write_end() and
the latest PNG specification for more information on that. If you
wish to write them before the image, fill them in now, and flag that
data as being valid. If you want to wait until after the data, don't
fill them until png_write_end(). For all the fields in png_info and
their data types, see png.h. For explanations of what the fields
contain, see the PNG specification.
Some of the more important parts of the png_info are:
png_set_IHDR(png_ptr, info_ptr, width, height,
bit_depth, color_type, interlace_type,
compression_type, filter_method)
width - holds the width of the image
in pixels (up to 2^31).
height - holds the height of the image
in pixels (up to 2^31).
bit_depth - holds the bit depth of one of the
src/Source/LibPNG/libpng.3 view on Meta::CPAN
compression_type - (must be
PNG_COMPRESSION_TYPE_DEFAULT)
filter_method - (must be PNG_FILTER_TYPE_DEFAULT
or, if you are writing a PNG to
be embedded in a MNG datastream,
can also be
PNG_INTRAPIXEL_DIFFERENCING)
If you call png_set_IHDR(), the call must appear before any of the
other png_set_*() functions, because they might require access to some of
the IHDR settings. The remaining png_set_*() functions can be called
in any order.
If you wish, you can reset the compression_type, interlace_type, or
filter_method later by calling png_set_IHDR() again; if you do this, the
width, height, bit_depth, and color_type must be the same in each call.
png_set_PLTE(png_ptr, info_ptr, palette,
num_palette);
palette - the palette for the file
(array of png_color)
num_palette - number of entries in the palette
png_set_gAMA(png_ptr, info_ptr, file_gamma);
png_set_gAMA_fixed(png_ptr, info_ptr, int_file_gamma);
file_gamma - the gamma at which the image was
created (PNG_INFO_gAMA)
int_file_gamma - 100,000 times the gamma at which
the image was created
png_set_cHRM(png_ptr, info_ptr, white_x, white_y, red_x, red_y,
green_x, green_y, blue_x, blue_y)
png_set_cHRM_XYZ(png_ptr, info_ptr, red_X, red_Y, red_Z, green_X,
green_Y, green_Z, blue_X, blue_Y, blue_Z)
png_set_cHRM_fixed(png_ptr, info_ptr, int_white_x, int_white_y,
int_red_x, int_red_y, int_green_x, int_green_y,
int_blue_x, int_blue_y)
png_set_cHRM_XYZ_fixed(png_ptr, info_ptr, int_red_X, int_red_Y,
int_red_Z, int_green_X, int_green_Y, int_green_Z,
int_blue_X, int_blue_Y, int_blue_Z)
{white,red,green,blue}_{x,y}
A color space encoding specified using the chromaticities
of the end points and the white point.
{red,green,blue}_{X,Y,Z}
A color space encoding specified using the encoding end
points - the CIE tristimulus specification of the intended
color of the red, green and blue channels in the PNG RGB
data. The white point is simply the sum of the three end
points.
png_set_sRGB(png_ptr, info_ptr, srgb_intent);
srgb_intent - the rendering intent
(PNG_INFO_sRGB) The presence of
the sRGB chunk means that the pixel
data is in the sRGB color space.
This chunk also implies specific
values of gAMA and cHRM. Rendering
intent is the CSS-1 property that
has been defined by the International
Color Consortium
(http://www.color.org).
It can be one of
PNG_sRGB_INTENT_SATURATION,
PNG_sRGB_INTENT_PERCEPTUAL,
PNG_sRGB_INTENT_ABSOLUTE, or
PNG_sRGB_INTENT_RELATIVE.
png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr,
srgb_intent);
srgb_intent - the rendering intent
(PNG_INFO_sRGB) The presence of the
sRGB chunk means that the pixel
data is in the sRGB color space.
This function also causes gAMA and
cHRM chunks with the specific values
that are consistent with sRGB to be
written.
png_set_iCCP(png_ptr, info_ptr, name, compression_type,
profile, proflen);
name - The profile name.
compression_type - The compression type; always
PNG_COMPRESSION_TYPE_BASE for PNG 1.0.
You may give NULL to this argument to
ignore it.
profile - International Color Consortium color
profile data. May contain NULs.
proflen - length of profile data in bytes.
png_set_sBIT(png_ptr, info_ptr, sig_bit);
sig_bit - the number of significant bits for
(PNG_INFO_sBIT) each of the gray, red,
green, and blue channels, whichever are
appropriate for the given color type
(png_color_16)
png_set_tRNS(png_ptr, info_ptr, trans_alpha,
num_trans, trans_color);
trans_alpha - array of alpha (transparency)
entries for palette (PNG_INFO_tRNS)
num_trans - number of transparent entries
(PNG_INFO_tRNS)
trans_color - graylevel or color sample values
(in order red, green, blue) of the
single transparent color for
non-paletted images (PNG_INFO_tRNS)
png_set_hIST(png_ptr, info_ptr, hist);
hist - histogram of palette (array of
png_uint_16) (PNG_INFO_hIST)
png_set_tIME(png_ptr, info_ptr, mod_time);
mod_time - time image was last modified
(PNG_VALID_tIME)
png_set_bKGD(png_ptr, info_ptr, background);
background - background color (of type
png_color_16p) (PNG_VALID_bKGD)
png_set_text(png_ptr, info_ptr, text_ptr, num_text);
text_ptr - array of png_text holding image
comments
text_ptr[i].compression - type of compression used
on "text" PNG_TEXT_COMPRESSION_NONE
PNG_TEXT_COMPRESSION_zTXt
PNG_ITXT_COMPRESSION_NONE
PNG_ITXT_COMPRESSION_zTXt
text_ptr[i].key - keyword for comment. Must contain
1-79 characters.
text_ptr[i].text - text comments for current
src/Source/LibPNG/libpng.3 view on Meta::CPAN
text_ptr[i].itxt_length - length of itxt string,
after decompression, 0 for tEXt/zTXt
text_ptr[i].lang - language of comment (NULL or
empty for unknown).
text_ptr[i].translated_keyword - keyword in UTF-8 (NULL
or empty for unknown).
Note that the itxt_length, lang, and lang_key
members of the text_ptr structure only exist when the
library is built with iTXt chunk support. Prior to
libpng-1.4.0 the library was built by default without
iTXt support. Also note that when iTXt is supported,
they contain NULL pointers when the "compression"
field contains PNG_TEXT_COMPRESSION_NONE or
PNG_TEXT_COMPRESSION_zTXt.
num_text - number of comments
png_set_sPLT(png_ptr, info_ptr, &palette_ptr,
num_spalettes);
palette_ptr - array of png_sPLT_struct structures
to be added to the list of palettes
in the info structure.
num_spalettes - number of palette structures to be
added.
png_set_oFFs(png_ptr, info_ptr, offset_x, offset_y,
unit_type);
offset_x - positive offset from the left
edge of the screen
offset_y - positive offset from the top
edge of the screen
unit_type - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
png_set_pHYs(png_ptr, info_ptr, res_x, res_y,
unit_type);
res_x - pixels/unit physical resolution
in x direction
res_y - pixels/unit physical resolution
in y direction
unit_type - PNG_RESOLUTION_UNKNOWN,
PNG_RESOLUTION_METER
png_set_sCAL(png_ptr, info_ptr, unit, width, height)
unit - physical scale units (an integer)
width - width of a pixel in physical scale units
height - height of a pixel in physical scale units
(width and height are doubles)
png_set_sCAL_s(png_ptr, info_ptr, unit, width, height)
unit - physical scale units (an integer)
width - width of a pixel in physical scale units
expressed as a string
height - height of a pixel in physical scale units
(width and height are strings like "2.54")
png_set_unknown_chunks(png_ptr, info_ptr, &unknowns,
num_unknowns)
unknowns - array of png_unknown_chunk
structures holding unknown chunks
unknowns[i].name - name of unknown chunk
unknowns[i].data - data of unknown chunk
unknowns[i].size - size of unknown chunk's data
unknowns[i].location - position to write chunk in file
0: do not write chunk
PNG_HAVE_IHDR: before PLTE
PNG_HAVE_PLTE: before IDAT
PNG_AFTER_IDAT: after IDAT
The "location" member is set automatically according to
what part of the output file has already been written.
You can change its value after calling png_set_unknown_chunks()
as demonstrated in pngtest.c. Within each of the "locations",
the chunks are sequenced according to their position in the
structure (that is, the value of "i", which is the order in which
the chunk was either read from the input file or defined with
png_set_unknown_chunks).
A quick word about text and num_text. text is an array of png_text
structures. num_text is the number of valid structures in the array.
Each png_text structure holds a language code, a keyword, a text value,
and a compression type.
The compression types have the same valid numbers as the compression
types of the image data. Currently, the only valid number is zero.
However, you can store text either compressed or uncompressed, unlike
images, which always have to be compressed. So if you don't want the
text compressed, set the compression type to PNG_TEXT_COMPRESSION_NONE.
Because tEXt and zTXt chunks don't have a language field, if you
specify PNG_TEXT_COMPRESSION_NONE or PNG_TEXT_COMPRESSION_zTXt
any language code or translated keyword will not be written out.
Until text gets around a few hundred bytes, it is not worth compressing it.
After the text has been written out to the file, the compression type
is set to PNG_TEXT_COMPRESSION_NONE_WR or PNG_TEXT_COMPRESSION_zTXt_WR,
so that it isn't written out again at the end (in case you are calling
png_write_end() with the same struct).
The keywords that are given in the PNG Specification are:
Title Short (one line) title or
caption for image
Author Name of image's creator
Description Description of image (possibly long)
src/Source/LibPNG/libpng.3 view on Meta::CPAN
words, not abbreviations. Keywords and text are in the ISO 8859-1
(Latin-1) character set (a superset of regular ASCII) and can not
contain NUL characters, and should not contain control or other
unprintable characters. To make the comments widely readable, stick
with basic ASCII, and avoid machine specific character set extensions
like the IBM-PC character set. The keyword must be present, but
you can leave off the text string on non-compressed pairs.
Compressed pairs must have a text string, as only the text string
is compressed anyway, so the compression would be meaningless.
PNG supports modification time via the png_time structure. Two
conversion routines are provided, png_convert_from_time_t() for
time_t and png_convert_from_struct_tm() for struct tm. The
time_t routine uses gmtime(). You don't have to use either of
these, but if you wish to fill in the png_time structure directly,
you should provide the time in universal time (GMT) if possible
instead of your local time. Note that the year number is the full
year (e.g. 1998, rather than 98 - PNG is year 2000 compliant!), and
that months start with 1.
If you want to store the time of the original image creation, you should
use a plain tEXt chunk with the "Creation Time" keyword. This is
necessary because the "creation time" of a PNG image is somewhat vague,
depending on whether you mean the PNG file, the time the image was
created in a non-PNG format, a still photo from which the image was
scanned, or possibly the subject matter itself. In order to facilitate
machine-readable dates, it is recommended that the "Creation Time"
tEXt chunk use RFC 1123 format dates (e.g. "22 May 1997 18:07:10 GMT"),
although this isn't a requirement. Unlike the tIME chunk, the
"Creation Time" tEXt chunk is not expected to be automatically changed
by the software. To facilitate the use of RFC 1123 dates, a function
png_convert_to_rfc1123_buffer(buffer, png_timep) is provided to
convert from PNG time to an RFC 1123 format string. The caller must provide
a writeable buffer of at least 29 bytes.
.SS Writing unknown chunks
You can use the png_set_unknown_chunks function to queue up private chunks
for writing. You give it a chunk name, location, raw data, and a size. You
also must use png_set_keep_unknown_chunks() to ensure that libpng will
handle them. That's all there is to it. The chunks will be written by the
next following png_write_info_before_PLTE, png_write_info, or png_write_end
function, depending upon the specified location. Any chunks previously
read into the info structure's unknown-chunk list will also be written out
in a sequence that satisfies the PNG specification's ordering rules.
Here is an example of writing two private chunks, prVt and miNE:
#ifdef PNG_WRITE_UNKNOWN_CHUNKS_SUPPORTED
/* Set unknown chunk data */
png_unknown_chunk unk_chunk[2];
strcpy((char *) unk_chunk[0].name, "prVt";
unk_chunk[0].data = (unsigned char *) "PRIVATE DATA";
unk_chunk[0].size = strlen(unk_chunk[0].data)+1;
unk_chunk[0].location = PNG_HAVE_IHDR;
strcpy((char *) unk_chunk[1].name, "miNE";
unk_chunk[1].data = (unsigned char *) "MY CHUNK DATA";
unk_chunk[1].size = strlen(unk_chunk[0].data)+1;
unk_chunk[1].location = PNG_AFTER_IDAT;
png_set_unknown_chunks(write_ptr, write_info_ptr,
unk_chunk, 2);
/* Needed because miNE is not safe-to-copy */
png_set_keep_unknown_chunks(png, PNG_HANDLE_CHUNK_ALWAYS,
(png_bytep) "miNE", 1);
# if PNG_LIBPNG_VER < 10600
/* Deal with unknown chunk location bug in 1.5.x and earlier */
png_set_unknown_chunk_location(png, info, 0, PNG_HAVE_IHDR);
png_set_unknown_chunk_location(png, info, 1, PNG_AFTER_IDAT);
# endif
# if PNG_LIBPNG_VER < 10500
/* PNG_AFTER_IDAT writes two copies of the chunk prior to libpng-1.5.0,
* one before IDAT and another after IDAT, so don't use it; only use
* PNG_HAVE_IHDR location. This call resets the location previously
* set by assignment and png_set_unknown_chunk_location() for chunk 1.
*/
png_set_unknown_chunk_location(png, info, 1, PNG_HAVE_IHDR);
# endif
#endif
.SS The high-level write interface
At this point there are two ways to proceed; through the high-level
write interface, or through a sequence of low-level write operations.
You can use the high-level interface if your image data is present
in the info structure. All defined output
transformations are permitted, enabled by the following masks.
src/Source/LibPNG/libpng.3 view on Meta::CPAN
to transparency
PNG_TRANSFORM_SWAP_ENDIAN Byte-swap 16-bit samples
PNG_TRANSFORM_STRIP_FILLER Strip out filler
bytes (deprecated).
PNG_TRANSFORM_STRIP_FILLER_BEFORE Strip out leading
filler bytes
PNG_TRANSFORM_STRIP_FILLER_AFTER Strip out trailing
filler bytes
If you have valid image data in the info structure (you can use
png_set_rows() to put image data in the info structure), simply do this:
png_write_png(png_ptr, info_ptr, png_transforms, NULL)
where png_transforms is an integer containing the bitwise OR of some set of
transformation flags. This call is equivalent to png_write_info(),
followed the set of transformations indicated by the transform mask,
then png_write_image(), and finally png_write_end().
(The final parameter of this call is not yet used. Someday it might point
to transformation parameters required by some future output transform.)
You must use png_transforms and not call any png_set_transform() functions
when you use png_write_png().
.SS The low-level write interface
If you are going the low-level route instead, you are now ready to
write all the file information up to the actual image data. You do
this with a call to png_write_info().
png_write_info(png_ptr, info_ptr);
Note that there is one transformation you may need to do before
png_write_info(). In PNG files, the alpha channel in an image is the
level of opacity. If your data is supplied as a level of transparency,
you can invert the alpha channel before you write it, so that 0 is
fully transparent and 255 (in 8-bit or paletted images) or 65535
(in 16-bit images) is fully opaque, with
png_set_invert_alpha(png_ptr);
This must appear before png_write_info() instead of later with the
other transformations because in the case of paletted images the tRNS
chunk data has to be inverted before the tRNS chunk is written. If
your image is not a paletted image, the tRNS data (which in such cases
represents a single color to be rendered as transparent) won't need to
be changed, and you can safely do this transformation after your
png_write_info() call.
If you need to write a private chunk that you want to appear before
the PLTE chunk when PLTE is present, you can write the PNG info in
two steps, and insert code to write your own chunk between them:
png_write_info_before_PLTE(png_ptr, info_ptr);
png_set_unknown_chunks(png_ptr, info_ptr, ...);
png_write_info(png_ptr, info_ptr);
After you've written the file information, you can set up the library
to handle any special transformations of the image data. The various
ways to transform the data will be described in the order that they
should occur. This is important, as some of these change the color
type and/or bit depth of the data, and some others only work on
certain color types and bit depths. Even though each transformation
checks to see if it has data that it can do something with, you should
make sure to only enable a transformation if it will be valid for the
data. For example, don't swap red and blue on grayscale data.
PNG files store RGB pixels packed into 3 or 6 bytes. This code tells
the library to strip input data that has 4 or 8 bytes per pixel down
to 3 or 6 bytes (or strip 2 or 4-byte grayscale+filler data to 1 or 2
bytes per pixel).
png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
where the 0 is unused, and the location is either PNG_FILLER_BEFORE or
PNG_FILLER_AFTER, depending upon whether the filler byte in the pixel
is stored XRGB or RGBX.
PNG files pack pixels of bit depths 1, 2, and 4 into bytes as small as
they can, resulting in, for example, 8 pixels per byte for 1 bit files.
If the data is supplied at 1 pixel per byte, use this code, which will
correctly pack the pixels into a single byte:
png_set_packing(png_ptr);
PNG files reduce possible bit depths to 1, 2, 4, 8, and 16. If your
data is of another bit depth, you can write an sBIT chunk into the
file so that decoders can recover the original data if desired.
/* Set the true bit depth of the image data */
if (color_type & PNG_COLOR_MASK_COLOR)
{
sig_bit.red = true_bit_depth;
sig_bit.green = true_bit_depth;
src/Source/LibPNG/libpng.3 view on Meta::CPAN
else
{
sig_bit.gray = true_bit_depth;
}
if (color_type & PNG_COLOR_MASK_ALPHA)
{
sig_bit.alpha = true_bit_depth;
}
png_set_sBIT(png_ptr, info_ptr, &sig_bit);
If the data is stored in the row buffer in a bit depth other than
one supported by PNG (e.g. 3 bit data in the range 0-7 for a 4-bit PNG),
this will scale the values to appear to be the correct bit depth as
is required by PNG.
png_set_shift(png_ptr, &sig_bit);
PNG files store 16-bit pixels in network byte order (big-endian,
ie. most significant bits first). This code would be used if they are
supplied the other way (little-endian, i.e. least significant bits
first, the way PCs store them):
if (bit_depth > 8)
png_set_swap(png_ptr);
If you are using packed-pixel images (1, 2, or 4 bits/pixel), and you
need to change the order the pixels are packed into bytes, you can use:
if (bit_depth < 8)
png_set_packswap(png_ptr);
PNG files store 3 color pixels in red, green, blue order. This code
would be used if they are supplied as blue, green, red:
png_set_bgr(png_ptr);
PNG files describe monochrome as black being zero and white being
one. This code would be used if the pixels are supplied with this reversed
(black being one and white being zero):
png_set_invert_mono(png_ptr);
Finally, you can write your own transformation function if none of
the existing ones meets your needs. This is done by setting a callback
with
png_set_write_user_transform_fn(png_ptr,
write_transform_fn);
You must supply the function
void write_transform_fn(png_structp png_ptr, png_row_infop
row_info, png_bytep data)
See pngtest.c for a working example. Your function will be called
before any of the other transformations are processed. If supported
libpng also supplies an information routine that may be called from
your callback:
png_get_current_row_number(png_ptr);
png_get_current_pass_number(png_ptr);
This returns the current row passed to the transform. With interlaced
images the value returned is the row in the input sub-image image. Use
PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
find the output pixel (x,y) given an interlaced sub-image pixel (row,col,pass).
The discussion of interlace handling above contains more information on how to
use these values.
You can also set up a pointer to a user structure for use by your
callback function.
png_set_user_transform_info(png_ptr, user_ptr, 0, 0);
The user_channels and user_depth parameters of this function are ignored
when writing; you can set them to zero as shown.
You can retrieve the pointer via the function png_get_user_transform_ptr().
For example:
voidp write_user_transform_ptr =
png_get_user_transform_ptr(png_ptr);
It is possible to have libpng flush any pending output, either manually,
or automatically after a certain number of lines have been written. To
flush the output stream a single time call:
png_write_flush(png_ptr);
and to have libpng flush the output stream periodically after a certain
number of scanlines have been written, call:
png_set_flush(png_ptr, nrows);
Note that the distance between rows is from the last time png_write_flush()
was called, or the first row of the image if it has never been called.
So if you write 50 lines, and then png_set_flush 25, it will flush the
output on the next scanline, and every 25 lines thereafter, unless
png_write_flush() is called before 25 more lines have been written.
If nrows is too small (less than about 10 lines for a 640 pixel wide
RGB image) the image compression may decrease noticeably (although this
may be acceptable for real-time applications). Infrequent flushing will
only degrade the compression performance by a few percent over images
that do not use flushing.
.SS Writing the image data
That's it for the transformations. Now you can write the image data.
The simplest way to do this is in one function call. If you have the
whole image in memory, you can just call png_write_image() and libpng
will write the image. You will need to pass in an array of pointers to
each row. This function automatically handles interlacing, so you don't
need to call png_set_interlace_handling() or call this function multiple
times, or any of that other stuff necessary with png_write_rows().
png_write_image(png_ptr, row_pointers);
where row_pointers is:
png_byte *row_pointers[height];
You can point to void or char or whatever you use for pixels.
If you don't want to write the whole image at once, you can
use png_write_rows() instead. If the file is not interlaced,
this is simple:
png_write_rows(png_ptr, row_pointers,
number_of_rows);
row_pointers is the same as in the png_write_image() call.
If you are just writing one row at a time, you can do this with
a single row_pointer instead of an array of row_pointers:
png_bytep row_pointer = row;
png_write_row(png_ptr, row_pointer);
When the file is interlaced, things can get a good deal more complicated.
The only currently (as of the PNG Specification version 1.2, dated July
1999) defined interlacing scheme for PNG files is the "Adam7" interlace
scheme, that breaks down an image into seven smaller images of varying
size. libpng will build these images for you, or you can do them
yourself. If you want to build them yourself, see the PNG specification
for details of which pixels to write when.
If you don't want libpng to handle the interlacing details, just
use png_set_interlace_handling() and call png_write_rows() the
correct number of times to write all the sub-images
(png_set_interlace_handling() returns the number of sub-images.)
If you want libpng to build the sub-images, call this before you start
writing any rows:
number_of_passes = png_set_interlace_handling(png_ptr);
This will return the number of passes needed. Currently, this is seven,
but may change if another interlace type is added.
Then write the complete image number_of_passes times.
png_write_rows(png_ptr, row_pointers, number_of_rows);
Think carefully before you write an interlaced image. Typically code that
reads such images reads all the image data into memory, uncompressed, before
doing any processing. Only code that can display an image on the fly can
take advantage of the interlacing and even then the image has to be exactly
the correct size for the output device, because scaling an image requires
adjacent pixels and these are not available until all the passes have been
read.
If you do write an interlaced image you will hardly ever need to handle
the interlacing yourself. Call png_set_interlace_handling() and use the
approach described above.
The only time it is conceivable that you will really need to write an
interlaced image pass-by-pass is when you have read one pass by pass and
made some pixel-by-pixel transformation to it, as described in the read
code above. In this case use the PNG_PASS_ROWS and PNG_PASS_COLS macros
to determine the size of each sub-image in turn and simply write the rows
you obtained from the read code.
.SS Finishing a sequential write
After you are finished writing the image, you should finish writing
the file. If you are interested in writing comments or time, you should
pass an appropriately filled png_info pointer. If you are not interested,
you can pass NULL.
png_write_end(png_ptr, info_ptr);
When you are done, you can free all memory used by libpng like this:
png_destroy_write_struct(&png_ptr, &info_ptr);
It is also possible to individually free the info_ptr members that
point to libpng-allocated storage with the following function:
png_free_data(png_ptr, info_ptr, mask, seq)
mask - identifies data to be freed, a mask
containing the bitwise OR of one or
more of
PNG_FREE_PLTE, PNG_FREE_TRNS,
PNG_FREE_HIST, PNG_FREE_ICCP,
PNG_FREE_PCAL, PNG_FREE_ROWS,
PNG_FREE_SCAL, PNG_FREE_SPLT,
PNG_FREE_TEXT, PNG_FREE_UNKN,
or simply PNG_FREE_ALL
seq - sequence number of item to be freed
(\-1 for all items)
This function may be safely called when the relevant storage has
already been freed, or has not yet been allocated, or was allocated
by the user and not by libpng, and will in those cases do nothing.
The "seq" parameter is ignored if only one item of the selected data
type, such as PLTE, is allowed. If "seq" is not \-1, and multiple items
are allowed for the data type identified in the mask, such as text or
sPLT, only the n'th item in the structure is freed, where n is "seq".
If you allocated data such as a palette that you passed in to libpng
with png_set_*, you must not free it until just before the call to
png_destroy_write_struct().
The default behavior is only to free data that was allocated internally
by libpng. This can be changed, so that libpng will not free the data,
or so that it will free data that was allocated by the user with png_malloc()
or png_calloc() and passed in via a png_set_*() function, with
png_data_freer(png_ptr, info_ptr, freer, mask)
freer - one of
PNG_DESTROY_WILL_FREE_DATA
PNG_SET_WILL_FREE_DATA
PNG_USER_WILL_FREE_DATA
mask - which data elements are affected
same choices as in png_free_data()
For example, to transfer responsibility for some data from a read structure
to a write structure, you could use
png_data_freer(read_ptr, read_info_ptr,
PNG_USER_WILL_FREE_DATA,
PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
png_data_freer(write_ptr, write_info_ptr,
PNG_DESTROY_WILL_FREE_DATA,
PNG_FREE_PLTE|PNG_FREE_tRNS|PNG_FREE_hIST)
thereby briefly reassigning responsibility for freeing to the user but
immediately afterwards reassigning it once more to the write_destroy
function. Having done this, it would then be safe to destroy the read
structure and continue to use the PLTE, tRNS, and hIST data in the write
structure.
This function only affects data that has already been allocated.
You can call this function before calling after the png_set_*() functions
to control whether the user or png_destroy_*() is supposed to free the data.
When the user assumes responsibility for libpng-allocated data, the
application must use
png_free() to free it, and when the user transfers responsibility to libpng
for data that the user has allocated, the user must have used png_malloc()
or png_calloc() to allocate it.
If you allocated text_ptr.text, text_ptr.lang, and text_ptr.translated_keyword
separately, do not transfer responsibility for freeing text_ptr to libpng,
because when libpng fills a png_text structure it combines these members with
the key member, and png_free_data() will free only text_ptr.key. Similarly,
if you transfer responsibility for free'ing text_ptr from libpng to your
application, your application must not separately free those members.
For a more compact example of writing a PNG image, see the file example.c.
.SH V. Simplified API
The simplified API, which became available in libpng-1.6.0, hides the details
of both libpng and the PNG file format itself.
It allows PNG files to be read into a very limited number of
in-memory bitmap formats or to be written from the same formats. If these
formats do not accommodate your needs then you can, and should, use the more
sophisticated APIs above - these support a wide variety of in-memory formats
and a wide variety of sophisticated transformations to those formats as well
as a wide variety of APIs to manipulate ancilliary information.
To read a PNG file using the simplified API:
1) Declare a 'png_image' structure (see below) on the
stack and memset() it to all zero.
2) Call the appropriate png_image_begin_read... function.
3) Set the png_image 'format' member to the required
format and allocate a buffer for the image.
4) Call png_image_finish_read to read the image into
your buffer.
There are no restrictions on the format of the PNG input itself; all valid
color types, bit depths, and interlace methods are acceptable, and the
input image is transformed as necessary to the requested in-memory format
during the png_image_finish_read() step.
To write a PNG file using the simplified API:
1) Declare a 'png_image' structure on the stack and memset()
it to all zero.
2) Initialize the members of the structure that describe the
image, setting the 'format' member to the format of the
image in memory.
3) Call the appropriate png_image_write... function with a
pointer to the image to write the PNG data.
png_image is a structure that describes the in-memory format of an image
when it is being read or define the in-memory format of an image that you
need to write. The "png_image" structure contains the following members:
png_uint_32 version Set to PNG_IMAGE_VERSION
png_uint_32 width Image width in pixels (columns)
png_uint_32 height Image height in pixels (rows)
png_uint_32 format Image format as defined below
png_uint_32 flags A bit mask containing informational flags
png_controlp opaque Initialize to NULL, free with png_image_free
png_uint_32 colormap_entries; Number of entries in the color-map
png_uint_32 warning_or_error;
char message[64];
In the event of an error or warning the following field warning_or_error
field will be set to a non-zero value and the 'message' field will contain
a '\0' terminated string with the libpng error or warning message. If both
warnings and an error were encountered, only the error is recorded. If there
are multiple warnings, only the first one is recorded.
The upper 30 bits of this value are reserved; the low two bits contain
a two bit code such that a value more than 1 indicates a failure in the API
just called:
0 - no warning or error
1 - warning
2 - error
src/Source/LibPNG/libpng.3 view on Meta::CPAN
channels are linear. Color channels use the RGB encoding (RGB end-points) of
the sRGB specification. This encoding is identified by the
PNG_FORMAT_FLAG_LINEAR flag below.
When an alpha channel is present it is expected to denote pixel coverage
of the color or luminance channels and is returned as an associated alpha
channel: the color/gray channels are scaled (pre-multiplied) by the alpha
value.
When a color-mapped image is used as a result of calling
png_image_read_colormap or png_image_write_colormap the channels are encoded
in the color-map and the descriptions above apply to the color-map entries.
The image data is encoded as small integers, value 0..255, that index the
entries in the color-map. One integer (one byte) is stored for each pixel.
PNG_FORMAT_*
The #defines to be used in png_image::format. Each #define identifies a
particular layout of channel data and, if present, alpha values. There are
separate defines for each of the two channel encodings.
A format is built up using single bit flag values. Not all combinations are
valid: use the bit flag values below for testing a format returned by the
read APIs, but set formats from the derived values.
When reading or writing color-mapped images the format should be set to the
format of the entries in the color-map then png_image_{read,write}_colormap
called to read or write the color-map and set the format correctly for the
image data. Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly!
NOTE: libpng can be built with particular features disabled, if you see
compiler errors because the definition of one of the following flags has been
compiled out it is because libpng does not have the required support. It is
possible, however, for the libpng configuration to enable the format on just
read or just write; in that case you may see an error at run time. You can
guard against this by checking for the definition of:
PNG_SIMPLIFIED_{READ,WRITE}_{BGR,AFIRST}_SUPPORTED
PNG_FORMAT_FLAG_ALPHA 0x01 format with an alpha channel
PNG_FORMAT_FLAG_COLOR 0x02 color format: otherwise grayscale
PNG_FORMAT_FLAG_LINEAR 0x04 png_uint_16 channels else png_byte
PNG_FORMAT_FLAG_COLORMAP 0x08 libpng use only
PNG_FORMAT_FLAG_BGR 0x10 BGR colors, else order is RGB
PNG_FORMAT_FLAG_AFIRST 0x20 alpha channel comes first
Supported formats are as follows. Future versions of libpng may support more
formats; for compatibility with older versions simply check if the format
macro is defined using #ifdef. These defines describe the in-memory layout
of the components of the pixels of the image.
First the single byte formats:
PNG_FORMAT_GRAY 0
PNG_FORMAT_GA PNG_FORMAT_FLAG_ALPHA
PNG_FORMAT_AG (PNG_FORMAT_GA|PNG_FORMAT_FLAG_AFIRST)
PNG_FORMAT_RGB PNG_FORMAT_FLAG_COLOR
src/Source/LibPNG/libpng.3 view on Meta::CPAN
PNG_FORMAT_LINEAR_Y PNG_FORMAT_FLAG_LINEAR
PNG_FORMAT_LINEAR_Y_ALPHA
(PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_ALPHA)
PNG_FORMAT_LINEAR_RGB
(PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR)
PNG_FORMAT_LINEAR_RGB_ALPHA
(PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR|
PNG_FORMAT_FLAG_ALPHA)
Color-mapped formats are obtained by calling png_image_{read,write}_colormap,
as appropriate after setting png_image::format to the format of the color-map
to be read or written. Applications may check the value of
PNG_FORMAT_FLAG_COLORMAP to see if they have called the colormap API. The
format of the color-map may be extracted using the following macro.
PNG_FORMAT_OF_COLORMAP(fmt) ((fmt) & ~PNG_FORMAT_FLAG_COLORMAP)
PNG_IMAGE macros
These are convenience macros to derive information from a png_image
structure. The PNG_IMAGE_SAMPLE_ macros return values appropriate to the
actual image sample values - either the entries in the color-map or the
pixels in the image. The PNG_IMAGE_PIXEL_ macros return corresponding values
for the pixels and will always return 1 after a call to
png_image_{read,write}_colormap. The remaining macros return information
about the rows in the image and the complete image.
NOTE: All the macros that take a png_image::format parameter are compile time
constants if the format parameter is, itself, a constant. Therefore these
macros can be used in array declarations and case labels where required.
Similarly the macros are also pre-processor constants (sizeof is not used) so
they can be used in #if tests.
First the information about the samples.
PNG_IMAGE_SAMPLE_CHANNELS(fmt)
Returns the total number of channels in a given format: 1..4
src/Source/LibPNG/libpng.3 view on Meta::CPAN
Returns the size in bytes of a single component of a pixel or color-map
entry (as appropriate) in the image.
PNG_IMAGE_SAMPLE_SIZE(fmt)
This is the size of the sample data for one sample. If the image is
color-mapped it is the size of one color-map entry (and image pixels are
one byte in size), otherwise it is the size of one image pixel.
PNG_IMAGE_COLORMAP_SIZE(fmt)
The size of the color-map required by the format; this is the size of the
color-map buffer passed to the png_image_{read,write}_colormap APIs, it is
a fixed number determined by the format so can easily be allocated on the
stack if necessary.
#define PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)\
(PNG_IMAGE_SAMPLE_CHANNELS(fmt) * 256)
/* The maximum size of the color-map required by the format expressed in a
* count of components. This can be used to compile-time allocate a
* color-map:
*
* png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
*
* png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
*
* Alternatively, use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
* information from one of the png_image_begin_read_ APIs and dynamically
* allocate the required memory.
*/
Corresponding information about the pixels
PNG_IMAGE_PIXEL_(test,fmt)
PNG_IMAGE_PIXEL_CHANNELS(fmt)
The number of separate channels (components) in a pixel; 1 for a
src/Source/LibPNG/libpng.3 view on Meta::CPAN
is the minimum 'row stride', the minimum count of components between each
row. For a color-mapped image this is the minimum number of bytes in a
row.
If you need the stride measured in bytes, row_stride_bytes is
PNG_IMAGE_ROW_STRIDE(image) * PNG_IMAGE_PIXEL_COMPONENT_SIZE(fmt)
plus any padding bytes that your application might need, for example
to start the next row on a 4-byte boundary.
PNG_IMAGE_BUFFER_SIZE(image, row_stride)
Returns the size, in bytes, of an image buffer given a png_image and a row
stride - the number of components to leave space for in each row. This
macro takes care of multiplying row_stride by PNG_IMAGE_PIXEL_COMONENT_SIZE
when the image has 2-byte components.
PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB == 0x01
This indicates the the RGB values of the in-memory bitmap do not
correspond to the red, green and blue end-points defined by sRGB.
PNG_IMAGE_FLAG_COLORMAP == 0x02
The PNG is color-mapped. If this flag is set png_image_read_colormap
can be used without further loss of image information. If it is not set
png_image_read_colormap will cause significant loss if the image has any
READ APIs
The png_image passed to the read APIs must have been initialized by setting
the png_controlp field 'opaque' to NULL (or, better, memset the whole thing.)
int png_image_begin_read_from_file( png_imagep image,
const char *file_name)
The named file is opened for read and the image header
is filled in from the PNG header in the file.
int png_image_begin_read_from_stdio (png_imagep image,
FILE* file)
The PNG header is read from the stdio FILE object.
int png_image_begin_read_from_memory(png_imagep image,
png_const_voidp memory, png_size_t size)
The PNG header is read from the given memory buffer.
int png_image_finish_read(png_imagep image,
png_colorp background, void *buffer,
png_int_32 row_stride, void *colormap));
Finish reading the image into the supplied buffer and
clean up the png_image structure.
row_stride is the step, in png_byte or png_uint_16 units
as appropriate, between adjacent rows. A positive stride
indicates that the top-most row is first in the buffer -
the normal top-down arrangement. A negative stride
indicates that the bottom-most row is first in the buffer.
background need only be supplied if an alpha channel must
be removed from a png_byte format and the removal is to be
done by compositing on a solid color; otherwise it may be
NULL and any composition will be done directly onto the
buffer. The value is an sRGB color to use for the
background, for grayscale output the green channel is used.
For linear output removing the alpha channel is always done
by compositing on black.
void png_image_free(png_imagep image)
Free any data allocated by libpng in image->opaque,
setting the pointer to NULL. May be called at any time
after the structure is initialized.
When the simplified API needs to convert between sRGB and linear colorspaces,
the actual sRGB transfer curve defined in the sRGB specification (see the
article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
approximation used elsewhere in libpng.
WRITE APIS
For write you must initialize a png_image structure to describe the image to
be written:
version: must be set to PNG_IMAGE_VERSION
opaque: must be initialized to NULL
width: image width in pixels
height: image height in rows
format: the format of the data you wish to write
flags: set to 0 unless one of the defined flags applies; set
PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB for color format images
where the RGB values do not correspond to the colors in sRGB.
colormap_entries: set to the number of entries in the color-map (0 to 256)
int png_image_write_to_file, (png_imagep image,
const char *file, int convert_to_8bit, const void *buffer,
png_int_32 row_stride, const void *colormap));
Write the image to the named file.
int png_image_write_to_stdio(png_imagep image, FILE *file,
int convert_to_8_bit, const void *buffer,
png_int_32 row_stride, const void *colormap)
Write the image to the given (FILE*).
With all write APIs if image is in one of the linear formats with
(png_uint_16) data then setting convert_to_8_bit will cause the output to be
a (png_byte) PNG gamma encoded according to the sRGB specification, otherwise
a 16-bit linear encoded PNG file is written.
With all APIs row_stride is handled as in the read APIs - it is the spacing
from one row to the next in component sized units (float) and if negative
indicates a bottom-up row layout in the buffer.
Note that the write API does not support interlacing, sub-8-bit pixels,
and indexed (paletted) images.
.SH VI. Modifying/Customizing libpng
There are two issues here. The first is changing how libpng does
standard things like memory allocation, input/output, and error handling.
The second deals with more complicated things like adding new chunks,
adding new transformations, and generally changing how libpng works.
Both of those are compile-time issues; that is, they are generally
determined at the time the code is written, and there is rarely a need
to provide the user with a means of changing them.
Memory allocation, input/output, and error handling
All of the memory allocation, input/output, and error handling in libpng
goes through callbacks that are user-settable. The default routines are
in pngmem.c, pngrio.c, pngwio.c, and pngerror.c, respectively. To change
these functions, call the appropriate png_set_*_fn() function.
Memory allocation is done through the functions png_malloc(), png_calloc(),
and png_free(). The png_malloc() and png_free() functions currently just
call the standard C functions and png_calloc() calls png_malloc() and then
clears the newly allocated memory to zero; note that png_calloc(png_ptr, size)
is not the same as the calloc(number, size) function provided by stdlib.h.
There is limited support for certain systems with segmented memory
architectures and the types of pointers declared by png.h match this; you
will have to use appropriate pointers in your application. If you prefer
to use a different method of allocating and freeing data, you can use
png_create_read_struct_2() or png_create_write_struct_2() to register your
own functions as described above. These functions also provide a void
pointer that can be retrieved via
mem_ptr=png_get_mem_ptr(png_ptr);
Your replacement memory functions must have prototypes as follows:
png_voidp malloc_fn(png_structp png_ptr,
png_alloc_size_t size);
void free_fn(png_structp png_ptr, png_voidp ptr);
Your malloc_fn() must return NULL in case of failure. The png_malloc()
function will normally call png_error() if it receives a NULL from the
system memory allocator or from your replacement malloc_fn().
Your free_fn() will never be called with a NULL ptr, since libpng's
png_free() checks for NULL before calling free_fn().
Input/Output in libpng is done through png_read() and png_write(),
which currently just call fread() and fwrite(). The FILE * is stored in
png_struct and is initialized via png_init_io(). If you wish to change
the method of I/O, the library supplies callbacks that you can set
through the function png_set_read_fn() and png_set_write_fn() at run
time, instead of calling the png_init_io() function. These functions
also provide a void pointer that can be retrieved via the function
png_get_io_ptr(). For example:
png_set_read_fn(png_structp read_ptr,
voidp read_io_ptr, png_rw_ptr read_data_fn)
png_set_write_fn(png_structp write_ptr,
voidp write_io_ptr, png_rw_ptr write_data_fn,
png_flush_ptr output_flush_fn);
voidp read_io_ptr = png_get_io_ptr(read_ptr);
voidp write_io_ptr = png_get_io_ptr(write_ptr);
The replacement I/O functions must have prototypes as follows:
void user_read_data(png_structp png_ptr,
png_bytep data, png_size_t length);
void user_write_data(png_structp png_ptr,
png_bytep data, png_size_t length);
void user_flush_data(png_structp png_ptr);
The user_read_data() function is responsible for detecting and
handling end-of-data errors.
Supplying NULL for the read, write, or flush functions sets them back
to using the default C stream functions, which expect the io_ptr to
point to a standard *FILE structure. It is probably a mistake
to use NULL for one of write_data_fn and output_flush_fn but not both
of them, unless you have built libpng with PNG_NO_WRITE_FLUSH defined.
It is an error to read from a write stream, and vice versa.
Error handling in libpng is done through png_error() and png_warning().
Errors handled through png_error() are fatal, meaning that png_error()
should never return to its caller. Currently, this is handled via
setjmp() and longjmp() (unless you have compiled libpng with
PNG_NO_SETJMP, in which case it is handled via PNG_ABORT()),
but you could change this to do things like exit() if you should wish,
as long as your function does not return.
On non-fatal errors, png_warning() is called
to print a warning message, and then control returns to the calling code.
By default png_error() and png_warning() print a message on stderr via
fprintf() unless the library is compiled with PNG_NO_CONSOLE_IO defined
(because you don't want the messages) or PNG_NO_STDIO defined (because
fprintf() isn't available). If you wish to change the behavior of the error
functions, you will need to set up your own message callbacks. These
functions are normally supplied at the time that the png_struct is created.
It is also possible to redirect errors and warnings to your own replacement
functions after png_create_*_struct() has been called by calling:
png_set_error_fn(png_structp png_ptr,
png_voidp error_ptr, png_error_ptr error_fn,
png_error_ptr warning_fn);
png_voidp error_ptr = png_get_error_ptr(png_ptr);
If NULL is supplied for either error_fn or warning_fn, then the libpng
default function will be used, calling fprintf() and/or longjmp() if a
problem is encountered. The replacement error functions should have
parameters as follows:
void user_error_fn(png_structp png_ptr,
png_const_charp error_msg);
void user_warning_fn(png_structp png_ptr,
png_const_charp warning_msg);
The motivation behind using setjmp() and longjmp() is the C++ throw and
catch exception handling methods. This makes the code much easier to write,
as there is no need to check every return code of every function call.
However, there are some uncertainties about the status of local variables
after a longjmp, so the user may want to be careful about doing anything
after setjmp returns non-zero besides returning itself. Consult your
compiler documentation for more details. For an alternative approach, you
may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net),
which is illustrated in pngvalid.c and in contrib/visupng.
Beginning in libpng-1.4.0, the png_set_benign_errors() API became available.
You can use this to handle certain errors (normally handled as errors)
as warnings.
png_set_benign_errors (png_ptr, int allowed);
allowed: 0: treat png_benign_error() as an error.
1: treat png_benign_error() as a warning.
As of libpng-1.6.0, the default condition is to treat benign errors as
warnings while reading and as errors while writing.
.SS Custom chunks
If you need to read or write custom chunks, you may need to get deeper
into the libpng code. The library now has mechanisms for storing
and writing chunks of unknown type; you can even declare callbacks
for custom chunks. However, this may not be good enough if the
library code itself needs to know about interactions between your
chunk and existing `intrinsic' chunks.
If you need to write a new intrinsic chunk, first read the PNG
specification. Acquire a first level of understanding of how it works.
Pay particular attention to the sections that describe chunk names,
and look at how other chunks were designed, so you can do things
similarly. Second, check out the sections of libpng that read and
write chunks. Try to find a chunk that is similar to yours and use
it as a template. More details can be found in the comments inside
the code. It is best to handle private or unknown chunks in a generic method,
via callback functions, instead of by modifying libpng functions. This
is illustrated in pngtest.c, which uses a callback function to handle a
private "vpAg" chunk and the new "sTER" chunk, which are both unknown to
libpng.
If you wish to write your own transformation for the data, look through
the part of the code that does the transformations, and check out some of
the simpler ones to get an idea of how they work. Try to find a similar
transformation to the one you want to add and copy off of it. More details
can be found in the comments inside the code itself.
.SS Configuring for gui/windowing platforms:
You will need to write new error and warning functions that use the GUI
interface, as described previously, and set them to be the error and
warning functions at the time that png_create_*_struct() is called,
in order to have them available during the structure initialization.
They can be changed later via png_set_error_fn(). On some compilers,
you may also have to change the memory allocators (png_malloc, etc.).
.SS Configuring zlib:
There are special functions to configure the compression. Perhaps the
most useful one changes the compression level, which currently uses
input compression values in the range 0 - 9. The library normally
uses the default compression level (Z_DEFAULT_COMPRESSION = 6). Tests
have shown that for a large majority of images, compression values in
the range 3-6 compress nearly as well as higher levels, and do so much
faster. For online applications it may be desirable to have maximum speed
(Z_BEST_SPEED = 1). With versions of zlib after v0.99, you can also
specify no compression (Z_NO_COMPRESSION = 0), but this would create
files larger than just storing the raw bitmap. You can specify the
compression level by calling:
#include zlib.h
png_set_compression_level(png_ptr, level);
Another useful one is to reduce the memory level used by the library.
The memory level defaults to 8, but it can be lowered if you are
short on memory (running DOS, for example, where you only have 640K).
Note that the memory level does have an effect on compression; among
other things, lower levels will result in sections of incompressible
data being emitted in smaller stored blocks, with a correspondingly
larger relative overhead of up to 15% in the worst case.
#include zlib.h
png_set_compression_mem_level(png_ptr, level);
The other functions are for configuring zlib. They are not recommended
for normal use and may result in writing an invalid PNG file. See
zlib.h for more information on what these mean.
#include zlib.h
png_set_compression_strategy(png_ptr,
strategy);
png_set_compression_window_bits(png_ptr,
window_bits);
png_set_compression_method(png_ptr, method);
This controls the size of the IDAT chunks (default 8192):
png_set_compression_buffer_size(png_ptr, size);
As of libpng version 1.5.4, additional APIs became
available to set these separately for non-IDAT
compressed chunks such as zTXt, iTXt, and iCCP:
#include zlib.h
#if PNG_LIBPNG_VER >= 10504
png_set_text_compression_level(png_ptr, level);
png_set_text_compression_mem_level(png_ptr, level);
png_set_text_compression_strategy(png_ptr,
strategy);
png_set_text_compression_window_bits(png_ptr,
window_bits);
png_set_text_compression_method(png_ptr, method);
#endif
.SS Controlling row filtering
If you want to control whether libpng uses filtering or not, which
filters are used, and how it goes about picking row filters, you
can call one of these functions. The selection and configuration
of row filters can have a significant impact on the size and
encoding speed and a somewhat lesser impact on the decoding speed
of an image. Filtering is enabled by default for RGB and grayscale
images (with and without alpha), but not for paletted images nor
for any images with bit depths less than 8 bits/pixel.
The 'method' parameter sets the main filtering method, which is
currently only '0' in the PNG 1.2 specification. The 'filters'
parameter sets which filter(s), if any, should be used for each
scanline. Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS
to turn filtering on and off, respectively.
Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise
ORed together with '|' to specify one or more filters to use.
These filters are described in more detail in the PNG specification.
If you intend to change the filter type during the course of writing
the image, you should start with flags set for all of the filters
you intend to use so that libpng can initialize its internal
structures appropriately for all of the filter types. (Note that this
means the first row must always be adaptively filtered, because libpng
currently does not allocate the filter buffers until png_write_row()
is called for the first time.)
filters = PNG_FILTER_NONE | PNG_FILTER_SUB
PNG_FILTER_UP | PNG_FILTER_AVG |
PNG_FILTER_PAETH | PNG_ALL_FILTERS;
png_set_filter(png_ptr, PNG_FILTER_TYPE_BASE,
filters);
The second parameter can also be
PNG_INTRAPIXEL_DIFFERENCING if you are
writing a PNG to be embedded in a MNG
datastream. This parameter must be the
same as the value of filter_method used
in png_set_IHDR().
It is also possible to influence how libpng chooses from among the
available filters. This is done in one or both of two ways - by
telling it how important it is to keep the same filter for successive
rows, and by telling it the relative computational costs of the filters.
double weights[3] = {1.5, 1.3, 1.1},
costs[PNG_FILTER_VALUE_LAST] =
{1.0, 1.3, 1.3, 1.5, 1.7};
png_set_filter_heuristics(png_ptr,
PNG_FILTER_HEURISTIC_WEIGHTED, 3,
weights, costs);
The weights are multiplying factors that indicate to libpng that the
row filter should be the same for successive rows unless another row filter
is that many times better than the previous filter. In the above example,
if the previous 3 filters were SUB, SUB, NONE, the SUB filter could have a
"sum of absolute differences" 1.5 x 1.3 times higher than other filters
and still be chosen, while the NONE filter could have a sum 1.1 times
higher than other filters and still be chosen. Unspecified weights are
taken to be 1.0, and the specified weights should probably be declining
like those above in order to emphasize recent filters over older filters.
The filter costs specify for each filter type a relative decoding cost
src/Source/LibPNG/libpng.3 view on Meta::CPAN
.SS Requesting debug printout
The macro definition PNG_DEBUG can be used to request debugging
printout. Set it to an integer value in the range 0 to 3. Higher
numbers result in increasing amounts of debugging information. The
information is printed to the "stderr" file, unless another file
name is specified in the PNG_DEBUG_FILE macro definition.
When PNG_DEBUG > 0, the following functions (macros) become available:
png_debug(level, message)
png_debug1(level, message, p1)
png_debug2(level, message, p1, p2)
in which "level" is compared to PNG_DEBUG to decide whether to print
the message, "message" is the formatted string to be printed,
and p1 and p2 are parameters that are to be embedded in the string
according to printf-style formatting directives. For example,
png_debug1(2, "foo=%d", foo);
is expanded to
if (PNG_DEBUG > 2)
fprintf(PNG_DEBUG_FILE, "foo=%d\en", foo);
When PNG_DEBUG is defined but is zero, the macros aren't defined, but you
can still use PNG_DEBUG to control your own debugging:
#ifdef PNG_DEBUG
fprintf(stderr, ...
#endif
When PNG_DEBUG = 1, the macros are defined, but only png_debug statements
having level = 0 will be printed. There aren't any such statements in
this version of libpng, but if you insert some they will be printed.
.SH VII. MNG support
The MNG specification (available at http://www.libpng.org/pub/mng) allows
certain extensions to PNG for PNG images that are embedded in MNG datastreams.
Libpng can support some of these extensions. To enable them, use the
png_permit_mng_features() function:
feature_set = png_permit_mng_features(png_ptr, mask)
mask is a png_uint_32 containing the bitwise OR of the
features you want to enable. These include
PNG_FLAG_MNG_EMPTY_PLTE
PNG_FLAG_MNG_FILTER_64
PNG_ALL_MNG_FEATURES
feature_set is a png_uint_32 that is the bitwise AND of
your mask with the set of MNG features that is
supported by the version of libpng that you are using.
It is an error to use this function when reading or writing a standalone
PNG file with the PNG 8-byte signature. The PNG datastream must be wrapped
in a MNG datastream. As a minimum, it must have the MNG 8-byte signature
and the MHDR and MEND chunks. Libpng does not provide support for these
or any other MNG chunks; your application must provide its own support for
them. You may wish to consider using libmng (available at
http://www.libmng.com) instead.
.SH VIII. Changes to Libpng from version 0.88
It should be noted that versions of libpng later than 0.96 are not
distributed by the original libpng author, Guy Schalnat, nor by
Andreas Dilger, who had taken over from Guy during 1996 and 1997, and
distributed versions 0.89 through 0.96, but rather by another member
of the original PNG Group, Glenn Randers-Pehrson. Guy and Andreas are
still alive and well, but they have moved on to other things.
The old libpng functions png_read_init(), png_write_init(),
png_info_init(), png_read_destroy(), and png_write_destroy() have been
moved to PNG_INTERNAL in version 0.95 to discourage their use. These
functions will be removed from libpng version 1.4.0.
The preferred method of creating and initializing the libpng structures is
via the png_create_read_struct(), png_create_write_struct(), and
png_create_info_struct() because they isolate the size of the structures
from the application, allow version error checking, and also allow the
use of custom error handling routines during the initialization, which
the old functions do not. The functions png_read_destroy() and
png_write_destroy() do not actually free the memory that libpng
allocated for these structs, but just reset the data structures, so they
can be used instead of png_destroy_read_struct() and
png_destroy_write_struct() if you feel there is too much system overhead
allocating and freeing the png_struct for each image read.
Setting the error callbacks via png_set_message_fn() before
png_read_init() as was suggested in libpng-0.88 is no longer supported
because this caused applications that do not use custom error functions
to fail if the png_ptr was not initialized to zero. It is still possible
to set the error callbacks AFTER png_read_init(), or to change them with
png_set_error_fn(), which is essentially the same function, but with a new
name to force compilation errors with applications that try to use the old
method.
Support for the sCAL, iCCP, iTXt, and sPLT chunks was added at libpng-1.0.6;
however, iTXt support was not enabled by default.
Starting with version 1.0.7, you can find out which version of the library
you are using at run-time:
png_uint_32 libpng_vn = png_access_version_number();
The number libpng_vn is constructed from the major version, minor
version with leading zero, and release number with leading zero,
(e.g., libpng_vn for version 1.0.7 is 10007).
Note that this function does not take a png_ptr, so you can call it
before you've created one.
You can also check which version of png.h you used when compiling your
application:
png_uint_32 application_vn = PNG_LIBPNG_VER;
.SH IX. Changes to Libpng from version 1.0.x to 1.2.x
Support for user memory management was enabled by default. To
accomplish this, the functions png_create_read_struct_2(),
png_create_write_struct_2(), png_set_mem_fn(), png_get_mem_ptr(),
png_malloc_default(), and png_free_default() were added.
Support for the iTXt chunk has been enabled by default as of
version 1.2.41.
Support for certain MNG features was enabled.
Support for numbered error messages was added. However, we never got
around to actually numbering the error messages. The function
png_set_strip_error_numbers() was added (Note: the prototype for this
function was inadvertently removed from png.h in PNG_NO_ASSEMBLER_CODE
builds of libpng-1.2.15. It was restored in libpng-1.2.36).
The png_malloc_warn() function was added at libpng-1.2.3. This issues
a png_warning and returns NULL instead of aborting when it fails to
acquire the requested memory allocation.
Support for setting user limits on image width and height was enabled
by default. The functions png_set_user_limits(), png_get_user_width_max(),
and png_get_user_height_max() were added at libpng-1.2.6.
The png_set_add_alpha() function was added at libpng-1.2.7.
The function png_set_expand_gray_1_2_4_to_8() was added at libpng-1.2.9.
Unlike png_set_gray_1_2_4_to_8(), the new function does not expand the
tRNS chunk to alpha. The png_set_gray_1_2_4_to_8() function is
deprecated.
A number of macro definitions in support of runtime selection of
assembler code features (especially Intel MMX code support) were
added at libpng-1.2.0:
PNG_ASM_FLAG_MMX_SUPPORT_COMPILED
PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU
PNG_ASM_FLAG_MMX_READ_COMBINE_ROW
PNG_ASM_FLAG_MMX_READ_INTERLACE
PNG_ASM_FLAG_MMX_READ_FILTER_SUB
PNG_ASM_FLAG_MMX_READ_FILTER_UP
PNG_ASM_FLAG_MMX_READ_FILTER_AVG
PNG_ASM_FLAG_MMX_READ_FILTER_PAETH
PNG_ASM_FLAGS_INITIALIZED
PNG_MMX_READ_FLAGS
PNG_MMX_FLAGS
PNG_MMX_WRITE_FLAGS
PNG_MMX_FLAGS
We added the following functions in support of runtime
selection of assembler code features:
png_get_mmx_flagmask()
png_set_mmx_thresholds()
png_get_asm_flags()
png_get_mmx_bitdepth_threshold()
png_get_mmx_rowbytes_threshold()
png_set_asm_flags()
We replaced all of these functions with simple stubs in libpng-1.2.20,
when the Intel assembler code was removed due to a licensing issue.
These macros are deprecated:
PNG_READ_TRANSFORMS_NOT_SUPPORTED
PNG_PROGRESSIVE_READ_NOT_SUPPORTED
PNG_NO_SEQUENTIAL_READ_SUPPORTED
PNG_WRITE_TRANSFORMS_NOT_SUPPORTED
PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED
PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED
src/Source/LibPNG/libpng.3 view on Meta::CPAN
They have been replaced, respectively, by:
PNG_NO_READ_TRANSFORMS
PNG_NO_PROGRESSIVE_READ
PNG_NO_SEQUENTIAL_READ
PNG_NO_WRITE_TRANSFORMS
PNG_NO_READ_ANCILLARY_CHUNKS
PNG_NO_WRITE_ANCILLARY_CHUNKS
PNG_MAX_UINT was replaced with PNG_UINT_31_MAX. It has been
deprecated since libpng-1.0.16 and libpng-1.2.6.
The function
png_check_sig(sig, num)
was replaced with
!png_sig_cmp(sig, 0, num)
It has been deprecated since libpng-0.90.
The function
png_set_gray_1_2_4_to_8()
which also expands tRNS to alpha was replaced with
png_set_expand_gray_1_2_4_to_8()
which does not. It has been deprecated since libpng-1.0.18 and 1.2.9.
.SH X. Changes to Libpng from version 1.0.x/1.2.x to 1.4.x
Private libpng prototypes and macro definitions were moved from
png.h and pngconf.h into a new pngpriv.h header file.
Functions png_set_benign_errors(), png_benign_error(), and
png_chunk_benign_error() were added.
Support for setting the maximum amount of memory that the application
will allocate for reading chunks was added, as a security measure.
The functions png_set_chunk_cache_max() and png_get_chunk_cache_max()
were added to the library.
We implemented support for I/O states by adding png_ptr member io_state
and functions png_get_io_chunk_name() and png_get_io_state() in pngget.c
We added PNG_TRANSFORM_GRAY_TO_RGB to the available high-level
input transforms.
Checking for and reporting of errors in the IHDR chunk is more thorough.
Support for global arrays was removed, to improve thread safety.
Some obsolete/deprecated macros and functions have been removed.
Typecasted NULL definitions such as
#define png_voidp_NULL (png_voidp)NULL
were eliminated. If you used these in your application, just use
NULL instead.
The png_struct and info_struct members "trans" and "trans_values" were
changed to "trans_alpha" and "trans_color", respectively.
The obsolete, unused pnggccrd.c and pngvcrd.c files and related makefiles
were removed.
The PNG_1_0_X and PNG_1_2_X macros were eliminated.
The PNG_LEGACY_SUPPORTED macro was eliminated.
Many WIN32_WCE #ifdefs were removed.
The functions png_read_init(info_ptr), png_write_init(info_ptr),
png_info_init(info_ptr), png_read_destroy(), and png_write_destroy()
have been removed. They have been deprecated since libpng-0.95.
The png_permit_empty_plte() was removed. It has been deprecated
since libpng-1.0.9. Use png_permit_mng_features() instead.
We removed the obsolete stub functions png_get_mmx_flagmask(),
png_set_mmx_thresholds(), png_get_asm_flags(),
png_get_mmx_bitdepth_threshold(), png_get_mmx_rowbytes_threshold(),
png_set_asm_flags(), and png_mmx_supported()
We removed the obsolete png_check_sig(), png_memcpy_check(), and
png_memset_check() functions. Instead use !png_sig_cmp(), memcpy(),
and memset(), respectively.
The function png_set_gray_1_2_4_to_8() was removed. It has been
deprecated since libpng-1.0.18 and 1.2.9, when it was replaced with
png_set_expand_gray_1_2_4_to_8() because the former function also
expanded any tRNS chunk to an alpha channel.
Macros for png_get_uint_16, png_get_uint_32, and png_get_int_32
were added and are used by default instead of the corresponding
functions. Unfortunately,
from libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
function) incorrectly returned a value of type png_uint_32.
We changed the prototype for png_malloc() from
png_malloc(png_structp png_ptr, png_uint_32 size)
to
png_malloc(png_structp png_ptr, png_alloc_size_t size)
This also applies to the prototype for the user replacement malloc_fn().
The png_calloc() function was added and is used in place of
of "png_malloc(); memset();" except in the case in png_read_png()
where the array consists of pointers; in this case a "for" loop is used
after the png_malloc() to set the pointers to NULL, to give robust.
behavior in case the application runs out of memory part-way through
the process.
We changed the prototypes of png_get_compression_buffer_size() and
png_set_compression_buffer_size() to work with png_size_t instead of
png_uint_32.
Support for numbered error messages was removed by default, since we
never got around to actually numbering the error messages. The function
png_set_strip_error_numbers() was removed from the library by default.
The png_zalloc() and png_zfree() functions are no longer exported.
The png_zalloc() function no longer zeroes out the memory that it
allocates. Applications that called png_zalloc(png_ptr, number, size)
can call png_calloc(png_ptr, number*size) instead, and can call
png_free() instead of png_zfree().
Support for dithering was disabled by default in libpng-1.4.0, because
it has not been well tested and doesn't actually "dither".
The code was not
removed, however, and could be enabled by building libpng with
PNG_READ_DITHER_SUPPORTED defined. In libpng-1.4.2, this support
was re-enabled, but the function was renamed png_set_quantize() to
reflect more accurately what it actually does. At the same time,
the PNG_DITHER_[RED,GREEN_BLUE]_BITS macros were also renamed to
PNG_QUANTIZE_[RED,GREEN,BLUE]_BITS, and PNG_READ_DITHER_SUPPORTED
was renamed to PNG_READ_QUANTIZE_SUPPORTED.
We removed the trailing '.' from the warning and error messages.
.SH XI. Changes to Libpng from version 1.4.x to 1.5.x
From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
function) incorrectly returned a value of type png_uint_32.
The incorrect macro was removed from libpng-1.4.5.
Checking for invalid palette index on write was added at libpng
1.5.10. If a pixel contains an invalid (out-of-range) index libpng issues
a benign error. This is enabled by default because this condition is an
error according to the PNG specification, Clause 11.3.2, but the error can
be ignored in each png_ptr with
png_set_check_for_invalid_index(png_ptr, allowed);
allowed - one of
0: disable benign error (accept the
invalid data without warning).
1: enable benign error (treat the
invalid data as an error or a
warning).
If the error is ignored, or if png_benign_error() treats it as a warning,
any invalid pixels are decoded as opaque black by the decoder and written
as-is by the encoder.
Retrieving the maximum palette index found was added at libpng-1.5.15.
This statement must appear after png_read_png() or png_read_image() while
reading, and after png_write_png() or png_write_image() while writing.
int max_palette = png_get_palette_max(png_ptr, info_ptr);
This will return the maximum palette index found in the image, or "\-1" if
the palette was not checked, or "0" if no palette was found. Note that this
does not account for any palette index used by ancillary chunks such as the
bKGD chunk; you must check those separately to determine the maximum
palette index actually used.
There are no substantial API changes between the non-deprecated parts of
the 1.4.5 API and the 1.5.0 API; however, the ability to directly access
members of the main libpng control structures, png_struct and png_info,
deprecated in earlier versions of libpng, has been completely removed from
libpng 1.5.
We no longer include zlib.h in png.h. The include statement has been moved
to pngstruct.h, where it is not accessible by applications. Applications that
need access to information in zlib.h will need to add the '#include "zlib.h"'
directive. It does not matter whether this is placed prior to or after
the '"#include png.h"' directive.
The png_sprintf(), png_strcpy(), and png_strncpy() macros are no longer used
and were removed.
We moved the png_strlen(), png_memcpy(), png_memset(), and png_memcmp()
macros into a private header file (pngpriv.h) that is not accessible to
applications.
In png_get_iCCP, the type of "profile" was changed from png_charpp
to png_bytepp, and in png_set_iCCP, from png_charp to png_const_bytep.
There are changes of form in png.h, including new and changed macros to
declare parts of the API. Some API functions with arguments that are
pointers to data not modified within the function have been corrected to
declare these arguments with PNG_CONST.
Much of the internal use of C macros to control the library build has also
changed and some of this is visible in the exported header files, in
particular the use of macros to control data and API elements visible
during application compilation may require significant revision to
application code. (It is extremely rare for an application to do this.)
Any program that compiled against libpng 1.4 and did not use deprecated
features or access internal library structures should compile and work
against libpng 1.5, except for the change in the prototype for
png_get_iCCP() and png_set_iCCP() API functions mentioned above.
libpng 1.5.0 adds PNG_ PASS macros to help in the reading and writing of
interlaced images. The macros return the number of rows and columns in
each pass and information that can be used to de-interlace and (if
absolutely necessary) interlace an image.
libpng 1.5.0 adds an API png_longjmp(png_ptr, value). This API calls
the application-provided png_longjmp_ptr on the internal, but application
initialized, longjmp buffer. It is provided as a convenience to avoid
the need to use the png_jmpbuf macro, which had the unnecessary side
effect of resetting the internal png_longjmp_ptr value.
libpng 1.5.0 includes a complete fixed point API. By default this is
present along with the corresponding floating point API. In general the
fixed point API is faster and smaller than the floating point one because
the PNG file format used fixed point, not floating point. This applies
even if the library uses floating point in internal calculations. A new
macro, PNG_FLOATING_ARITHMETIC_SUPPORTED, reveals whether the library
uses floating point arithmetic (the default) or fixed point arithmetic
internally for performance critical calculations such as gamma correction.
In some cases, the gamma calculations may produce slightly different
results. This has changed the results in png_rgb_to_gray and in alpha
composition (png_set_background for example). This applies even if the
original image was already linear (gamma == 1.0) and, therefore, it is
not necessary to linearize the image. This is because libpng has *not*
been changed to optimize that case correctly, yet.
Fixed point support for the sCAL chunk comes with an important caveat;
the sCAL specification uses a decimal encoding of floating point values
and the accuracy of PNG fixed point values is insufficient for
representation of these values. Consequently a "string" API
(png_get_sCAL_s and png_set_sCAL_s) is the only reliable way of reading
arbitrary sCAL chunks in the absence of either the floating point API or
internal floating point calculations. Starting with libpng-1.5.0, both
of these functions are present when PNG_sCAL_SUPPORTED is defined. Prior
to libpng-1.5.0, their presence also depended upon PNG_FIXED_POINT_SUPPORTED
being defined and PNG_FLOATING_POINT_SUPPORTED not being defined.
Applications no longer need to include the optional distribution header
file pngusr.h or define the corresponding macros during application
build in order to see the correct variant of the libpng API. From 1.5.0
application code can check for the corresponding _SUPPORTED macro:
#ifdef PNG_INCH_CONVERSIONS_SUPPORTED
/* code that uses the inch conversion APIs. */
#endif
This macro will only be defined if the inch conversion functions have been
compiled into libpng. The full set of macros, and whether or not support
has been compiled in, are available in the header file pnglibconf.h.
This header file is specific to the libpng build. Notice that prior to
1.5.0 the _SUPPORTED macros would always have the default definition unless
reset by pngusr.h or by explicit settings on the compiler command line.
These settings may produce compiler warnings or errors in 1.5.0 because
of macro redefinition.
Applications can now choose whether to use these macros or to call the
corresponding function by defining PNG_USE_READ_MACROS or
PNG_NO_USE_READ_MACROS before including png.h. Notice that this is
only supported from 1.5.0; defining PNG_NO_USE_READ_MACROS prior to 1.5.0
will lead to a link failure.
Prior to libpng-1.5.4, the zlib compressor used the same set of parameters
when compressing the IDAT data and textual data such as zTXt and iCCP.
In libpng-1.5.4 we reinitialized the zlib stream for each type of data.
We added five png_set_text_*() functions for setting the parameters to
use with textual data.
Prior to libpng-1.5.4, the PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
option was off by default, and slightly inaccurate scaling occurred.
This option can no longer be turned off, and the choice of accurate
or inaccurate 16-to-8 scaling is by using the new png_set_scale_16_to_8()
API for accurate scaling or the old png_set_strip_16_to_8() API for simple
chopping. In libpng-1.5.4, the PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
macro became PNG_READ_SCALE_16_TO_8_SUPPORTED, and the PNG_READ_16_TO_8
macro became PNG_READ_STRIP_16_TO_8_SUPPORTED, to enable the two
png_set_*_16_to_8() functions separately.
Prior to libpng-1.5.4, the png_set_user_limits() function could only be
used to reduce the width and height limits from the value of
PNG_USER_WIDTH_MAX and PNG_USER_HEIGHT_MAX, although this document said
that it could be used to override them. Now this function will reduce or
increase the limits.
Starting in libpng-1.5.10, the user limits can be set en masse with the
configuration option PNG_SAFE_LIMITS_SUPPORTED. If this option is enabled,
a set of "safe" limits is applied in pngpriv.h. These can be overridden by
application calls to png_set_user_limits(), png_set_user_chunk_cache_max(),
and/or png_set_user_malloc_max() that increase or decrease the limits. Also,
in libpng-1.5.10 the default width and height limits were increased
from 1,000,000 to 0x7ffffff (i.e., made unlimited). Therefore, the
limits are now
default safe
png_user_width_max 0x7fffffff 1,000,000
png_user_height_max 0x7fffffff 1,000,000
png_user_chunk_cache_max 0 (unlimited) 128
png_user_chunk_malloc_max 0 (unlimited) 8,000,000
The png_set_option() function (and the "options" member of the png struct) was
added to libpng-1.5.15.
The library now supports a complete fixed point implementation and can
thus be used on systems that have no floating point support or very
limited or slow support. Previously gamma correction, an essential part
of complete PNG support, required reasonably fast floating point.
As part of this the choice of internal implementation has been made
independent of the choice of fixed versus floating point APIs and all the
missing fixed point APIs have been implemented.
The exact mechanism used to control attributes of API functions has
changed, as described in the INSTALL file.
A new test program, pngvalid, is provided in addition to pngtest.
pngvalid validates the arithmetic accuracy of the gamma correction
calculations and includes a number of validations of the file format.
A subset of the full range of tests is run when "make check" is done
(in the 'configure' build.) pngvalid also allows total allocated memory
usage to be evaluated and performs additional memory overwrite validation.
Many changes to individual feature macros have been made. The following
are the changes most likely to be noticed by library builders who
configure libpng:
1) All feature macros now have consistent naming:
#define PNG_NO_feature turns the feature off
#define PNG_feature_SUPPORTED turns the feature on
pnglibconf.h contains one line for each feature macro which is either:
#define PNG_feature_SUPPORTED
if the feature is supported or:
/*#undef PNG_feature_SUPPORTED*/
if it is not. Library code consistently checks for the 'SUPPORTED' macro.
It does not, and libpng applications should not, check for the 'NO' macro
which will not normally be defined even if the feature is not supported.
The 'NO' macros are only used internally for setting or not setting the
corresponding 'SUPPORTED' macros.
Compatibility with the old names is provided as follows:
PNG_INCH_CONVERSIONS turns on PNG_INCH_CONVERSIONS_SUPPORTED
And the following definitions disable the corresponding feature:
src/Source/LibPNG/libpng.3 view on Meta::CPAN
PNG_FLOATING_ARITHMETIC_SUPPORTED chooses between the internal floating
point implementation or the fixed point one. Typically the fixed point
implementation is larger and slower than the floating point implementation
on a system that supports floating point; however, it may be faster on a
system which lacks floating point hardware and therefore uses a software
emulation.
4) Added PNG_{READ,WRITE}_INT_FUNCTIONS_SUPPORTED. This allows the
functions to read and write ints to be disabled independently of
PNG_USE_READ_MACROS, which allows libpng to be built with the functions
even though the default is to use the macros - this allows applications
to choose at app buildtime whether or not to use macros (previously
impossible because the functions weren't in the default build.)
.SH XII. Changes to Libpng from version 1.5.x to 1.6.x
A "simplified API" has been added (see documentation in png.h and a simple
example in contrib/examples/pngtopng.c). The new publicly visible API
includes the following:
macros:
PNG_FORMAT_*
PNG_IMAGE_*
structures:
png_control
png_image
read functions
png_image_begin_read_from_file()
png_image_begin_read_from_stdio()
png_image_begin_read_from_memory()
png_image_finish_read()
png_image_free()
write functions
png_image_write_to_file()
png_image_write_to_stdio()
Starting with libpng-1.6.0, you can configure libpng to prefix all exported
symbols, using the PNG_PREFIX macro.
We no longer include string.h in png.h. The include statement has been moved
to pngpriv.h, where it is not accessible by applications. Applications that
need access to information in string.h must add an '#include <string.h>'
directive. It does not matter whether this is placed prior to or after
the '#include "png.h"' directive.
The following API are now DEPRECATED:
png_info_init_3()
png_convert_to_rfc1123() which has been replaced
with png_convert_to_rfc1123_buffer()
png_malloc_default()
png_free_default()
png_reset_zstream()
The following have been removed:
png_get_io_chunk_name(), which has been replaced
with png_get_io_chunk_type(). The new
function returns a 32-bit integer instead of
a string.
The png_sizeof(), png_strlen(), png_memcpy(), png_memcmp(), and
png_memset() macros are no longer used in the libpng sources and
have been removed. These had already been made invisible to applications
(i.e., defined in the private pngpriv.h header file) since libpng-1.5.0.
The signatures of many exported functions were changed, such that
png_structp became png_structrp or png_const_structrp
png_infop became png_inforp or png_const_inforp
where "rp" indicates a "restricted pointer".
Error detection in some chunks has improved; in particular the iCCP chunk
reader now does pretty complete validation of the basic format. Some bad
profiles that were previously accepted are now accepted with a warning or
rejected, depending upon the png_set_benign_errors() setting, in particular
the very old broken Microsoft/HP 3144-byte sRGB profile. Starting with
libpng-1.6.11, recognizing and checking sRGB profiles can be avoided by
means of
#if defined(PNG_SKIP_sRGB_CHECK_PROFILE) && \
defined(PNG_SET_OPTION_SUPPORTED)
png_set_option(png_ptr, PNG_SKIP_sRGB_CHECK_PROFILE,
PNG_OPTION_ON);
#endif
It's not a good idea to do this if you are using the new "simplified API",
which needs to be able to recognize sRGB profiles conveyed via the iCCP
chunk.
The PNG spec requirement that only grayscale profiles may appear in images
with color type 0 or 4 and that even if the image only contains gray pixels,
only RGB profiles may appear in images with color type 2, 3, or 6, is now
enforced. The sRGB chunk is allowed to appear in images with any color type
and is interpreted by libpng to convey a one-tracer-curve gray profile or a
three-tracer-curve RGB profile as appropriate.
Prior to libpng-1.6.0 a warning would be issued if the iTXt chunk contained
an empty language field or an empty translated keyword. Both of these
are allowed by the PNG specification, so these warnings are no longer issued.
The library now issues an error if the application attempts to set a
transform after it calls png_read_update_info() or if it attempts to call
both png_read_update_info() and png_start_read_image() or to call either
of them more than once.
The default condition for benign_errors is now to treat benign errors as
warnings while reading and as errors while writing.
The library now issues a warning if both background processing and RGB to
gray are used when gamma correction happens. As with previous versions of
the library the results are numerically very incorrect in this case.
There are some minor arithmetic changes in some transforms such as
png_set_background(), that might be detected by certain regression tests.
Unknown chunk handling has been improved internally, without any API change.
This adds more correct option control of the unknown handling, corrects
a pre-existing bug where the per-chunk 'keep' setting is ignored, and makes
it possible to skip IDAT chunks in the sequential reader.
The machine-generated configure files are no longer included in branches
libpng16 and later of the GIT repository. They continue to be included
in the tarball releases, however.
Libpng-1.6.0 through 1.6.2 used the CMF bytes at the beginning of the IDAT
stream to set the size of the sliding window for reading instead of using the
default 32-kbyte sliding window size. It was discovered that there are
hundreds of PNG files in the wild that have incorrect CMF bytes that caused
zlib to issue the "invalid distance too far back" error and reject the file.
Libpng-1.6.3 and later calculate their own safe CMF from the image dimensions,
provide a way to revert to the libpng-1.5.x behavior (ignoring the CMF bytes
and using a 32-kbyte sliding window), by using
png_set_option(png_ptr, PNG_MAXIMUM_INFLATE_WINDOW,
PNG_OPTION_ON);
and provide a tool (contrib/tools/pngfix) for rewriting a PNG file while
optimizing the CMF bytes in its IDAT chunk correctly.
Libpng-1.6.0 and libpng-1.6.1 wrote uncompressed iTXt chunks with the wrong
length, which resulted in PNG files that cannot be read beyond the bad iTXt
chunk. This error was fixed in libpng-1.6.3, and a tool (called
contrib/tools/png-fix-itxt) has been added to the libpng distribution.
.SH XIII. Detecting libpng
The png_get_io_ptr() function has been present since libpng-0.88, has never
changed, and is unaffected by conditional compilation macros. It is the
best choice for use in configure scripts for detecting the presence of any
libpng version since 0.88. In an autoconf "configure.in" you could use
AC_CHECK_LIB(png, png_get_io_ptr, ...
.SH XV. Source code repository
Since about February 2009, version 1.2.34, libpng has been under "git" source
control. The git repository was built from old libpng-x.y.z.tar.gz files
going back to version 0.70. You can access the git repository (read only)
at
git://git.code.sf.net/p/libpng/code
or you can browse it with a web browser by selecting the "code" button at
https://sourceforge.net/projects/libpng
Patches can be sent to glennrp at users.sourceforge.net or to
png-mng-implement at lists.sourceforge.net or you can upload them to
the libpng bug tracker at
http://libpng.sourceforge.net
We also accept patches built from the tar or zip distributions, and
simple verbal discriptions of bug fixes, reported either to the
SourceForge bug tracker, to the png-mng-implement at lists.sf.net
mailing list, or directly to glennrp.
.SH XV. Coding style
Our coding style is similar to the "Allman" style
(See http://en.wikipedia.org/wiki/Indent_style#Allman_style), with curly
braces on separate lines:
if (condition)
{
src/Source/LibPNG/libpng.3 view on Meta::CPAN
used them in the past in some now-abandoned MMX assembler
code.
Functions and their curly braces are not indented, and
exported functions are marked with PNGAPI:
/* This is a public function that is visible to
* application programmers. It does thus-and-so.
*/
void PNGAPI
png_exported_function(png_ptr, png_info, foo)
{
body;
}
The return type and decorations are placed on a separate line
ahead of the function name, as illustrated above.
The prototypes for all exported functions appear in png.h,
above the comment that says
/* Maintainer: Put new public prototypes here ... */
We mark all non-exported functions with "/* PRIVATE */"":
void /* PRIVATE */
png_non_exported_function(png_ptr, png_info, foo)
{
body;
}
The prototypes for non-exported functions (except for those in
pngtest) appear in pngpriv.h above the comment that says
/* Maintainer: Put new private prototypes here ^ */
To avoid polluting the global namespace, the names of all exported
functions and variables begin with "png_", and all publicly visible C
preprocessor macros begin with "PNG". We request that applications that
use libpng *not* begin any of their own symbols with either of these strings.
We put a space after the "sizeof" operator and we omit the
optional parentheses around its argument when the argument
is an expression, not a type name, and we always enclose the
sizeof operator, with its argument, in parentheses:
(sizeof (png_uint_32))
(sizeof array)
Prior to libpng-1.6.0 we used a "png_sizeof()" macro, formatted as
though it were a function.
Control keywords if, for, while, and switch are always followed by a space
to distinguish them from function calls, which have no trailing space.
We put a space after each comma and after each semicolon
in "for" statements, and we put spaces before and after each
C binary operator and after "for" or "while", and before
"?". We don't put a space between a typecast and the expression
being cast, nor do we put one between a function name and the
src/Source/LibPNG/libpng.3 view on Meta::CPAN
We prefer to use underscores in variable names rather than camelCase, except
for a few type names that we inherit from zlib.h.
We prefer "if (something != 0)" and "if (something == 0)"
over "if (something)" and if "(!something)", respectively.
We do not use the TAB character for indentation in the C sources.
Lines do not exceed 80 characters.
Other rules can be inferred by inspecting the libpng source.
.SH XVI. Y2K Compliance in libpng
December 22, 2014
Since the PNG Development group is an ad-hoc body, we can't make
an official declaration.
This is your unofficial assurance that libpng from version 0.71 and
upward through 1.6.16 are Y2K compliant. It is my belief that earlier
versions were also Y2K compliant.
Libpng only has two year fields. One is a 2-byte unsigned integer
that will hold years up to 65535. The other, which is deprecated,
holds the date in text format, and will hold years up to 9999.
The integer is
"png_uint_16 year" in png_time_struct.
The string is
"char time_buffer[29]" in png_struct. This is no longer used
in libpng-1.6.x and will be removed from libpng-1.7.0.
There are seven time-related functions:
png_convert_to_rfc_1123_buffer() in png.c
(formerly png_convert_to_rfc_1152() in error, and
also formerly png_convert_to_rfc_1123())
png_convert_from_struct_tm() in pngwrite.c, called
in pngwrite.c
png_convert_from_time_t() in pngwrite.c
png_get_tIME() in pngget.c
png_handle_tIME() in pngrutil.c, called in pngread.c
png_set_tIME() in pngset.c
png_write_tIME() in pngwutil.c, called in pngwrite.c
All appear to handle dates properly in a Y2K environment. The
png_convert_from_time_t() function calls gmtime() to convert from system
clock time, which returns (year - 1900), which we properly convert to
the full 4-digit year. There is a possibility that applications using
libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
function, or that they are incorrectly passing only a 2-digit year
instead of "year - 1900" into the png_convert_from_struct_tm() function,
but this is not under our control. The libpng documentation has always
stated that it works with 4-digit years, and the APIs have been
documented as such.
The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned
integer to hold the year, and can hold years as large as 65535.
zlib, upon which libpng depends, is also Y2K compliant. It contains
no date-related code.
Glenn Randers-Pehrson
libpng maintainer
PNG Development Group
.SH NOTE
Note about libpng version numbers:
Due to various miscommunications, unforeseen code incompatibilities
and occasional factors outside the authors' control, version numbering
on the library has not always been consistent and straightforward.
The following table summarizes matters since version 0.89c, which was
the first widely used release:
source png.h png.h shared-lib
version string int version
------- ------ ----- ----------
0.89c ("beta 3") 0.89 89 1.0.89
0.90 ("beta 4") 0.90 90 0.90
0.95 ("beta 5") 0.95 95 0.95
0.96 ("beta 6") 0.96 96 0.96
0.97b ("beta 7") 1.00.97 97 1.0.1
0.97c 0.97 97 2.0.97
0.98 0.98 98 2.0.98
0.99 0.99 98 2.0.99
0.99a-m 0.99 99 2.0.99
1.00 1.00 100 2.1.0
1.0.0 1.0.0 100 2.1.0
1.0.0 (from here on, the 100 2.1.0
1.0.1 png.h string is 10001 2.1.0
1.0.1a-e identical to the 10002 from here on, the
1.0.2 source version) 10002 shared library is 2.V
1.0.2a-b 10003 where V is the source
1.0.1 10001 code version except as
1.0.1a-e 10002 2.1.0.1a-e noted.
1.0.2 10002 2.1.0.2
1.0.2a-b 10003 2.1.0.2a-b
1.0.3 10003 2.1.0.3
1.0.3a-d 10004 2.1.0.3a-d
1.0.4 10004 2.1.0.4
src/Source/LibPNG/libpng.3 view on Meta::CPAN
1.6.15beta01-08 16 10615 16.so.16.15[.0]
1.6.15rc01-03 16 10615 16.so.16.15[.0]
1.6.15 16 10615 16.so.16.15[.0]
1.6.16beta01-03 16 10616 16.so.16.16[.0]
1.6.16rc01-02 16 10616 16.so.16.16[.0]
1.6.16 16 10616 16.so.16.16[.0]
Henceforth the source version will match the shared-library minor
and patch numbers; the shared-library major version number will be
used for changes in backward compatibility, as it is intended. The
PNG_PNGLIB_VER macro, which is not used within libpng but is available
for applications, is an unsigned integer of the form xyyzz corresponding
to the source version x.y.z (leading zeros in y and z). Beta versions
were given the previous public release number plus a letter, until
version 1.0.6j; from then on they were given the upcoming public
release number plus "betaNN" or "rcN".
.SH "SEE ALSO"
.BR "png"(5), " libpngpf"(3), " zlib"(3), " deflate"(5), " " and " zlib"(5)
.LP
.IR libpng :
.IP
http://libpng.sourceforge.net (follow the [DOWNLOAD] link)
http://www.libpng.org/pub/png
.LP
.IR zlib :
.IP
(generally) at the same location as
.I libpng
or at
.br
ftp://ftp.info-zip.org/pub/infozip/zlib
.LP
.IR PNG specification: RFC 2083
.IP
(generally) at the same location as
.I libpng
or at
.br
ftp://ds.internic.net/rfc/rfc2083.txt
.br
or (as a W3C Recommendation) at
.br
http://www.w3.org/TR/REC-png.html
.LP
In the case of any inconsistency between the PNG specification
and this library, the specification takes precedence.
.SH AUTHORS
This man page: Glenn Randers-Pehrson
<glennrp at users.sourceforge.net>
The contributing authors would like to thank all those who helped
with testing, bug fixes, and patience. This wouldn't have been
possible without all of you.
Thanks to Frank J. T. Wojcik for helping with the documentation.
Libpng version 1.6.16 - December 22, 2014:
Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
Supported by the PNG development group
.br
png-mng-implement at lists.sf.net
(subscription required; visit
png-mng-implement at lists.sourceforge.net (subscription required; visit
https://lists.sourceforge.net/lists/listinfo/png-mng-implement
to subscribe).
.SH COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
(This copy of the libpng notices is provided for your convenience. In case of
any discrepancy between this copy and the notices in the file png.h that is
included in the libpng distribution, the latter shall prevail.)
If you modify libpng you may insert additional notices immediately following
this sentence.
This code is released under the libpng license.
libpng versions 1.2.6, August 15, 2004, through 1.6.16, December 22, 2014, are
Copyright (c) 2004,2006-2014 Glenn Randers-Pehrson, and are
distributed according to the same disclaimer and license as libpng-1.2.5
with the following individual added to the list of Contributing Authors
Cosmin Truta
libpng versions 1.0.7, July 1, 2000, through 1.2.5 - October 3, 2002, are
Copyright (c) 2000-2002 Glenn Randers-Pehrson, and are
distributed according to the same disclaimer and license as libpng-1.0.6
with the following individuals added to the list of Contributing Authors
Simon-Pierre Cadieux
Eric S. Raymond
Gilles Vollant
and with the following additions to the disclaimer:
There is no warranty against interference with your
enjoyment of the library or against infringement.
There is no warranty that our efforts or the library
will fulfill any of your particular purposes or needs.
This library is provided with all faults, and the entire
risk of satisfactory quality, performance, accuracy, and
effort is with the user.
libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
Copyright (c) 1998, 1999 Glenn Randers-Pehrson
Distributed according to the same disclaimer and license as libpng-0.96,
with the following individuals added to the list of Contributing Authors:
Tom Lane
Glenn Randers-Pehrson
Willem van Schaik
libpng versions 0.89, June 1996, through 0.96, May 1997, are
Copyright (c) 1996, 1997 Andreas Dilger
Distributed according to the same disclaimer and license as libpng-0.88,
with the following individuals added to the list of Contributing Authors:
John Bowler
Kevin Bracey
Sam Bushell
Magnus Holmgren
Greg Roelofs
Tom Tanner
libpng versions 0.5, May 1995, through 0.88, January 1996, are
Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
For the purposes of this copyright and license, "Contributing Authors"
is defined as the following set of individuals:
Andreas Dilger
Dave Martindale
Guy Eric Schalnat
Paul Schmidt
Tim Wegner
src/Source/LibPNG/libpng.3 view on Meta::CPAN
3. This Copyright notice may not be removed or altered from
any source or altered source distribution.
The Contributing Authors and Group 42, Inc. specifically permit, without
fee, and encourage the use of this source code as a component to
supporting the PNG file format in commercial products. If you use this
source code in a product, acknowledgment is not required but would be
appreciated.
A "png_get_copyright" function is available, for convenient use in "about"
boxes and the like:
printf("%s",png_get_copyright(NULL));
Also, the PNG logo (in PNG format, of course) is supplied in the
files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
Libpng is OSI Certified Open Source Software. OSI Certified Open Source is a
certification mark of the Open Source Initiative.
Glenn Randers-Pehrson
glennrp at users.sourceforge.net
December 22, 2014
.\" end of man page
src/Source/LibPNG/libpngpf.3 view on Meta::CPAN
.TH LIBPNGPF 3 "December 22, 2014"
.SH NAME
libpng \- Portable Network Graphics (PNG) Reference Library 1.6.16
(private functions)
.SH SYNOPSIS
\fB#include \fI"pngpriv.h"
\fBAs of libpng version \fP\fI1.5.1\fP\fB, this section is no longer \fP\fImaintained\fP\fB, now that the private function prototypes are hidden in pngpriv.h and not accessible to applications. Look in pngpriv.h for the prototypes and a short descrip...
.SH DESCRIPTION
The functions previously listed here are used privately by libpng and are not
available for use by applications. They are not "exported" to applications
using shared libraries.
.SH SEE ALSO
.BR "png"(5), " libpng"(3), " zlib"(3), " deflate"(5), " " and " zlib"(5)
.SH AUTHOR
Glenn Randers-Pehrson
src/Source/LibPNG/png.5 view on Meta::CPAN
.TH PNG 5 "December 22, 2014"
.SH NAME
png \- Portable Network Graphics (PNG) format
.SH DESCRIPTION
PNG (Portable Network Graphics) is an extensible file format for the
lossless, portable, well-compressed storage of raster images. PNG provides
a patent-free replacement for GIF and can also replace many
common uses of TIFF. Indexed-color, grayscale, and truecolor images are
supported, plus an optional alpha channel. Sample depths range from
1 to 16 bits.
.br
PNG is designed to work well in online viewing applications, such as the
World Wide Web, so it is fully streamable with a progressive display
option. PNG is robust, providing both full file integrity checking and
fast, simple detection of common transmission errors. Also, PNG can store
gamma and chromaticity data for improved color matching on heterogeneous
platforms.
.SH "SEE ALSO"
.BR "libpng"(3), " libpngpf"(3), " zlib"(3), " deflate"(5), " " and " zlib"(5)
.LP
PNG specification (second edition), November 2003:
.IP
.br
<http://www.w3.org/TR/2003/REC-PNG-20031110/
PNG 1.2 specification, July 1999:
.IP
.br
http://www.libpng.org/pub/png
.LP
PNG 1.0 specification, October 1996:
.IP
.br
RFC 2083
.IP
.br
ftp://ds.internic.net/rfc/rfc2083.txt
.br
or (as a W3C Recommendation) at
.br
http://www.w3.org/TR/REC-png.html
.SH AUTHORS
This man page: Glenn Randers-Pehrson
.LP
Portable Network Graphics (PNG) Specification (Second Edition)
Information technology - Computer graphics and image processing -
Portable Network Graphics (PNG): Functional specification.
ISO/IEC 15948:2003 (E) (November 10, 2003): David Duce and others.
.LP
Portable Network Graphics (PNG) Specification Version 1.2 (July 8, 1999):
Glenn Randers-Pehrson and others (png-list).
.LP
Portable Network Graphics (PNG) Specification Version 1.0 (October 1, 1996):
Thomas Boutell and others (png-list).
.LP
.SH COPYRIGHT NOTICE
.LP
This man page is Copyright (c) 1998-2006 Glenn Randers-Pehrson. See png.h
for conditions of use and distribution.
.LP
The PNG Specification (Second Edition) is
Copyright (c) 2003 W3C. (MIT, ERCIM, Keio), All Rights Reserved.
.LP
The PNG-1.2 specification is copyright (c) 1999 Glenn Randers-Pehrson.
See the specification for conditions of use and distribution.
.LP
The PNG-1.0 specification is copyright (c) 1996 Massachusetts Institute of
Technology. See the specification for conditions of use and distribution.
src/Source/LibPNG/png.c view on Meta::CPAN
/* png.c - location for general purpose libpng functions
*
* Last changed in libpng 1.6.16 [December 22, 2014]
* Copyright (c) 1998-2014 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*/
#include "pngpriv.h"
/* Generate a compiler error if there is an old png.h in the search path. */
typedef png_libpng_version_1_6_16 Your_png_h_is_not_version_1_6_16;
/* Tells libpng that we have already handled the first "num_bytes" bytes
* of the PNG file signature. If the PNG data is embedded into another
* stream we can set num_bytes = 8 so that libpng will not attempt to read
* or write any of the magic bytes before it starts on the IHDR.
*/
#ifdef PNG_READ_SUPPORTED
void PNGAPI
png_set_sig_bytes(png_structrp png_ptr, int num_bytes)
{
png_debug(1, "in png_set_sig_bytes");
if (png_ptr == NULL)
return;
if (num_bytes > 8)
png_error(png_ptr, "Too many bytes for PNG signature");
png_ptr->sig_bytes = (png_byte)(num_bytes < 0 ? 0 : num_bytes);
}
/* Checks whether the supplied bytes match the PNG signature. We allow
* checking less than the full 8-byte signature so that those apps that
* already read the first few bytes of a file to determine the file type
* can simply check the remaining bytes for extra assurance. Returns
* an integer less than, equal to, or greater than zero if sig is found,
* respectively, to be less than, to match, or be greater than the correct
* PNG signature (this is the same behavior as strcmp, memcmp, etc).
*/
int PNGAPI
png_sig_cmp(png_const_bytep sig, png_size_t start, png_size_t num_to_check)
{
png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10};
if (num_to_check > 8)
num_to_check = 8;
else if (num_to_check < 1)
return (-1);
if (start > 7)
return (-1);
if (start + num_to_check > 8)
num_to_check = 8 - start;
return ((int)(memcmp(&sig[start], &png_signature[start], num_to_check)));
}
#endif /* READ */
#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
/* Function to allocate memory for zlib */
PNG_FUNCTION(voidpf /* PRIVATE */,
png_zalloc,(voidpf png_ptr, uInt items, uInt size),PNG_ALLOCATED)
{
png_alloc_size_t num_bytes = size;
if (png_ptr == NULL)
return NULL;
if (items >= (~(png_alloc_size_t)0)/size)
{
png_warning (png_voidcast(png_structrp, png_ptr),
"Potential overflow in png_zalloc()");
return NULL;
}
num_bytes *= items;
return png_malloc_warn(png_voidcast(png_structrp, png_ptr), num_bytes);
}
/* Function to free memory for zlib */
void /* PRIVATE */
png_zfree(voidpf png_ptr, voidpf ptr)
{
png_free(png_voidcast(png_const_structrp,png_ptr), ptr);
}
/* Reset the CRC variable to 32 bits of 1's. Care must be taken
* in case CRC is > 32 bits to leave the top bits 0.
*/
void /* PRIVATE */
png_reset_crc(png_structrp png_ptr)
{
/* The cast is safe because the crc is a 32 bit value. */
png_ptr->crc = (png_uint_32)crc32(0, Z_NULL, 0);
}
/* Calculate the CRC over a section of data. We can only pass as
* much data to this routine as the largest single buffer size. We
* also check that this data will actually be used before going to the
* trouble of calculating it.
*/
void /* PRIVATE */
png_calculate_crc(png_structrp png_ptr, png_const_bytep ptr, png_size_t length)
{
int need_crc = 1;
if (PNG_CHUNK_ANCILLARY(png_ptr->chunk_name) != 0)
{
if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) ==
(PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN))
need_crc = 0;
}
else /* critical */
{
if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0)
need_crc = 0;
}
/* 'uLong' is defined in zlib.h as unsigned long; this means that on some
* systems it is a 64 bit value. crc32, however, returns 32 bits so the
* following cast is safe. 'uInt' may be no more than 16 bits, so it is
* necessary to perform a loop here.
*/
if (need_crc != 0 && length > 0)
{
uLong crc = png_ptr->crc; /* Should never issue a warning */
do
{
uInt safe_length = (uInt)length;
if (safe_length == 0)
safe_length = (uInt)-1; /* evil, but safe */
crc = crc32(crc, ptr, safe_length);
/* The following should never issue compiler warnings; if they do the
* target system has characteristics that will probably violate other
* assumptions within the libpng code.
*/
ptr += safe_length;
length -= safe_length;
}
while (length > 0);
/* And the following is always safe because the crc is only 32 bits. */
png_ptr->crc = (png_uint_32)crc;
}
}
/* Check a user supplied version number, called from both read and write
* functions that create a png_struct.
*/
int
png_user_version_check(png_structrp png_ptr, png_const_charp user_png_ver)
{
/* Libpng versions 1.0.0 and later are binary compatible if the version
* string matches through the second '.'; we must recompile any
* applications that use any older library version.
*/
if (user_png_ver != NULL)
{
int i = -1;
int found_dots = 0;
do
{
i++;
if (user_png_ver[i] != PNG_LIBPNG_VER_STRING[i])
png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
if (user_png_ver[i] == '.')
found_dots++;
} while (found_dots < 2 && user_png_ver[i] != 0 &&
PNG_LIBPNG_VER_STRING[i] != 0);
}
else
png_ptr->flags |= PNG_FLAG_LIBRARY_MISMATCH;
if ((png_ptr->flags & PNG_FLAG_LIBRARY_MISMATCH) != 0)
{
#ifdef PNG_WARNINGS_SUPPORTED
size_t pos = 0;
char m[128];
pos = png_safecat(m, (sizeof m), pos,
"Application built with libpng-");
pos = png_safecat(m, (sizeof m), pos, user_png_ver);
pos = png_safecat(m, (sizeof m), pos, " but running with ");
pos = png_safecat(m, (sizeof m), pos, PNG_LIBPNG_VER_STRING);
PNG_UNUSED(pos)
png_warning(png_ptr, m);
#endif
#ifdef PNG_ERROR_NUMBERS_SUPPORTED
png_ptr->flags = 0;
#endif
return 0;
}
/* Success return. */
return 1;
}
/* Generic function to create a png_struct for either read or write - this
* contains the common initialization.
*/
PNG_FUNCTION(png_structp /* PRIVATE */,
png_create_png_struct,(png_const_charp user_png_ver, png_voidp error_ptr,
png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
png_malloc_ptr malloc_fn, png_free_ptr free_fn),PNG_ALLOCATED)
{
png_struct create_struct;
# ifdef PNG_SETJMP_SUPPORTED
jmp_buf create_jmp_buf;
# endif
/* This temporary stack-allocated structure is used to provide a place to
* build enough context to allow the user provided memory allocator (if any)
* to be called.
*/
memset(&create_struct, 0, (sizeof create_struct));
/* Added at libpng-1.2.6 */
# ifdef PNG_USER_LIMITS_SUPPORTED
create_struct.user_width_max = PNG_USER_WIDTH_MAX;
create_struct.user_height_max = PNG_USER_HEIGHT_MAX;
# ifdef PNG_USER_CHUNK_CACHE_MAX
/* Added at libpng-1.2.43 and 1.4.0 */
create_struct.user_chunk_cache_max = PNG_USER_CHUNK_CACHE_MAX;
# endif
# ifdef PNG_USER_CHUNK_MALLOC_MAX
/* Added at libpng-1.2.43 and 1.4.1, required only for read but exists
* in png_struct regardless.
*/
create_struct.user_chunk_malloc_max = PNG_USER_CHUNK_MALLOC_MAX;
# endif
# endif
/* The following two API calls simply set fields in png_struct, so it is safe
* to do them now even though error handling is not yet set up.
*/
# ifdef PNG_USER_MEM_SUPPORTED
png_set_mem_fn(&create_struct, mem_ptr, malloc_fn, free_fn);
# else
PNG_UNUSED(mem_ptr)
PNG_UNUSED(malloc_fn)
PNG_UNUSED(free_fn)
# endif
/* (*error_fn) can return control to the caller after the error_ptr is set,
* this will result in a memory leak unless the error_fn does something
* extremely sophisticated. The design lacks merit but is implicit in the
* API.
*/
png_set_error_fn(&create_struct, error_ptr, error_fn, warn_fn);
# ifdef PNG_SETJMP_SUPPORTED
if (!setjmp(create_jmp_buf))
{
/* Temporarily fake out the longjmp information until we have
* successfully completed this function. This only works if we have
* setjmp() support compiled in, but it is safe - this stuff should
* never happen.
*/
create_struct.jmp_buf_ptr = &create_jmp_buf;
create_struct.jmp_buf_size = 0; /*stack allocation*/
create_struct.longjmp_fn = longjmp;
# else
{
# endif
/* Call the general version checker (shared with read and write code):
*/
if (png_user_version_check(&create_struct, user_png_ver) != 0)
{
png_structrp png_ptr = png_voidcast(png_structrp,
png_malloc_warn(&create_struct, (sizeof *png_ptr)));
if (png_ptr != NULL)
{
/* png_ptr->zstream holds a back-pointer to the png_struct, so
* this can only be done now:
*/
create_struct.zstream.zalloc = png_zalloc;
create_struct.zstream.zfree = png_zfree;
create_struct.zstream.opaque = png_ptr;
# ifdef PNG_SETJMP_SUPPORTED
/* Eliminate the local error handling: */
create_struct.jmp_buf_ptr = NULL;
create_struct.jmp_buf_size = 0;
create_struct.longjmp_fn = 0;
# endif
*png_ptr = create_struct;
/* This is the successful return point */
return png_ptr;
}
}
}
/* A longjmp because of a bug in the application storage allocator or a
* simple failure to allocate the png_struct.
*/
return NULL;
}
/* Allocate the memory for an info_struct for the application. */
PNG_FUNCTION(png_infop,PNGAPI
png_create_info_struct,(png_const_structrp png_ptr),PNG_ALLOCATED)
{
png_inforp info_ptr;
png_debug(1, "in png_create_info_struct");
if (png_ptr == NULL)
return NULL;
/* Use the internal API that does not (or at least should not) error out, so
* that this call always returns ok. The application typically sets up the
* error handling *after* creating the info_struct because this is the way it
* has always been done in 'example.c'.
*/
info_ptr = png_voidcast(png_inforp, png_malloc_base(png_ptr,
(sizeof *info_ptr)));
if (info_ptr != NULL)
memset(info_ptr, 0, (sizeof *info_ptr));
return info_ptr;
}
/* This function frees the memory associated with a single info struct.
* Normally, one would use either png_destroy_read_struct() or
* png_destroy_write_struct() to free an info struct, but this may be
* useful for some applications. From libpng 1.6.0 this function is also used
* internally to implement the png_info release part of the 'struct' destroy
* APIs. This ensures that all possible approaches free the same data (all of
* it).
*/
void PNGAPI
png_destroy_info_struct(png_const_structrp png_ptr, png_infopp info_ptr_ptr)
{
png_inforp info_ptr = NULL;
png_debug(1, "in png_destroy_info_struct");
if (png_ptr == NULL)
return;
if (info_ptr_ptr != NULL)
info_ptr = *info_ptr_ptr;
if (info_ptr != NULL)
{
/* Do this first in case of an error below; if the app implements its own
* memory management this can lead to png_free calling png_error, which
* will abort this routine and return control to the app error handler.
* An infinite loop may result if it then tries to free the same info
* ptr.
*/
*info_ptr_ptr = NULL;
png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
memset(info_ptr, 0, (sizeof *info_ptr));
png_free(png_ptr, info_ptr);
}
}
/* Initialize the info structure. This is now an internal function (0.89)
* and applications using it are urged to use png_create_info_struct()
* instead. Use deprecated in 1.6.0, internal use removed (used internally it
* is just a memset).
*
* NOTE: it is almost inconceivable that this API is used because it bypasses
* the user-memory mechanism and the user error handling/warning mechanisms in
* those cases where it does anything other than a memset.
*/
PNG_FUNCTION(void,PNGAPI
png_info_init_3,(png_infopp ptr_ptr, png_size_t png_info_struct_size),
PNG_DEPRECATED)
{
png_inforp info_ptr = *ptr_ptr;
png_debug(1, "in png_info_init_3");
if (info_ptr == NULL)
return;
if ((sizeof (png_info)) > png_info_struct_size)
{
*ptr_ptr = NULL;
/* The following line is why this API should not be used: */
free(info_ptr);
info_ptr = png_voidcast(png_inforp, png_malloc_base(NULL,
(sizeof *info_ptr)));
*ptr_ptr = info_ptr;
}
/* Set everything to 0 */
memset(info_ptr, 0, (sizeof *info_ptr));
}
/* The following API is not called internally */
void PNGAPI
png_data_freer(png_const_structrp png_ptr, png_inforp info_ptr,
int freer, png_uint_32 mask)
{
png_debug(1, "in png_data_freer");
if (png_ptr == NULL || info_ptr == NULL)
return;
if (freer == PNG_DESTROY_WILL_FREE_DATA)
info_ptr->free_me |= mask;
else if (freer == PNG_USER_WILL_FREE_DATA)
info_ptr->free_me &= ~mask;
else
png_error(png_ptr, "Unknown freer parameter in png_data_freer");
}
void PNGAPI
png_free_data(png_const_structrp png_ptr, png_inforp info_ptr, png_uint_32 mask,
int num)
{
png_debug(1, "in png_free_data");
if (png_ptr == NULL || info_ptr == NULL)
return;
#ifdef PNG_TEXT_SUPPORTED
/* Free text item num or (if num == -1) all text items */
if (info_ptr->text != 0 &&
((mask & PNG_FREE_TEXT) & info_ptr->free_me) != 0)
{
if (num != -1)
{
png_free(png_ptr, info_ptr->text[num].key);
info_ptr->text[num].key = NULL;
}
else
{
int i;
for (i = 0; i < info_ptr->num_text; i++)
png_free(png_ptr, info_ptr->text[i].key);
png_free(png_ptr, info_ptr->text);
info_ptr->text = NULL;
info_ptr->num_text = 0;
}
}
#endif
#ifdef PNG_tRNS_SUPPORTED
/* Free any tRNS entry */
if (((mask & PNG_FREE_TRNS) & info_ptr->free_me) != 0)
{
png_free(png_ptr, info_ptr->trans_alpha);
info_ptr->trans_alpha = NULL;
info_ptr->valid &= ~PNG_INFO_tRNS;
}
#endif
#ifdef PNG_sCAL_SUPPORTED
/* Free any sCAL entry */
if (((mask & PNG_FREE_SCAL) & info_ptr->free_me) != 0)
{
png_free(png_ptr, info_ptr->scal_s_width);
png_free(png_ptr, info_ptr->scal_s_height);
info_ptr->scal_s_width = NULL;
info_ptr->scal_s_height = NULL;
info_ptr->valid &= ~PNG_INFO_sCAL;
}
#endif
#ifdef PNG_pCAL_SUPPORTED
/* Free any pCAL entry */
if (((mask & PNG_FREE_PCAL) & info_ptr->free_me) != 0)
{
png_free(png_ptr, info_ptr->pcal_purpose);
png_free(png_ptr, info_ptr->pcal_units);
info_ptr->pcal_purpose = NULL;
info_ptr->pcal_units = NULL;
if (info_ptr->pcal_params != NULL)
{
int i;
for (i = 0; i < info_ptr->pcal_nparams; i++)
png_free(png_ptr, info_ptr->pcal_params[i]);
png_free(png_ptr, info_ptr->pcal_params);
info_ptr->pcal_params = NULL;
}
info_ptr->valid &= ~PNG_INFO_pCAL;
}
#endif
#ifdef PNG_iCCP_SUPPORTED
/* Free any profile entry */
if (((mask & PNG_FREE_ICCP) & info_ptr->free_me) != 0)
{
png_free(png_ptr, info_ptr->iccp_name);
png_free(png_ptr, info_ptr->iccp_profile);
info_ptr->iccp_name = NULL;
info_ptr->iccp_profile = NULL;
info_ptr->valid &= ~PNG_INFO_iCCP;
}
#endif
#ifdef PNG_sPLT_SUPPORTED
/* Free a given sPLT entry, or (if num == -1) all sPLT entries */
if (info_ptr->splt_palettes != 0 &&
((mask & PNG_FREE_SPLT) & info_ptr->free_me) != 0)
{
if (num != -1)
{
png_free(png_ptr, info_ptr->splt_palettes[num].name);
png_free(png_ptr, info_ptr->splt_palettes[num].entries);
info_ptr->splt_palettes[num].name = NULL;
info_ptr->splt_palettes[num].entries = NULL;
}
else
{
if (info_ptr->splt_palettes_num != 0)
{
int i;
for (i = 0; i < info_ptr->splt_palettes_num; i++)
{
png_free(png_ptr, info_ptr->splt_palettes[i].name);
png_free(png_ptr, info_ptr->splt_palettes[i].entries);
}
png_free(png_ptr, info_ptr->splt_palettes);
info_ptr->splt_palettes = NULL;
info_ptr->splt_palettes_num = 0;
}
info_ptr->valid &= ~PNG_INFO_sPLT;
}
}
#endif
#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
if (info_ptr->unknown_chunks != 0 &&
((mask & PNG_FREE_UNKN) & info_ptr->free_me) != 0)
{
if (num != -1)
{
png_free(png_ptr, info_ptr->unknown_chunks[num].data);
info_ptr->unknown_chunks[num].data = NULL;
}
else
{
int i;
if (info_ptr->unknown_chunks_num != 0)
{
for (i = 0; i < info_ptr->unknown_chunks_num; i++)
png_free(png_ptr, info_ptr->unknown_chunks[i].data);
png_free(png_ptr, info_ptr->unknown_chunks);
info_ptr->unknown_chunks = NULL;
info_ptr->unknown_chunks_num = 0;
}
}
}
#endif
#ifdef PNG_hIST_SUPPORTED
/* Free any hIST entry */
if (((mask & PNG_FREE_HIST) & info_ptr->free_me) != 0)
{
png_free(png_ptr, info_ptr->hist);
info_ptr->hist = NULL;
info_ptr->valid &= ~PNG_INFO_hIST;
}
#endif
/* Free any PLTE entry that was internally allocated */
if (((mask & PNG_FREE_PLTE) & info_ptr->free_me) != 0)
{
png_free(png_ptr, info_ptr->palette);
info_ptr->palette = NULL;
info_ptr->valid &= ~PNG_INFO_PLTE;
info_ptr->num_palette = 0;
}
#ifdef PNG_INFO_IMAGE_SUPPORTED
/* Free any image bits attached to the info structure */
if (((mask & PNG_FREE_ROWS) & info_ptr->free_me) != 0)
{
if (info_ptr->row_pointers != 0)
{
png_uint_32 row;
for (row = 0; row < info_ptr->height; row++)
png_free(png_ptr, info_ptr->row_pointers[row]);
png_free(png_ptr, info_ptr->row_pointers);
info_ptr->row_pointers = NULL;
}
info_ptr->valid &= ~PNG_INFO_IDAT;
}
#endif
if (num != -1)
mask &= ~PNG_FREE_MUL;
info_ptr->free_me &= ~mask;
}
#endif /* READ || WRITE */
/* This function returns a pointer to the io_ptr associated with the user
* functions. The application should free any memory associated with this
* pointer before png_write_destroy() or png_read_destroy() are called.
*/
png_voidp PNGAPI
png_get_io_ptr(png_const_structrp png_ptr)
{
if (png_ptr == NULL)
return (NULL);
return (png_ptr->io_ptr);
}
#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
# ifdef PNG_STDIO_SUPPORTED
/* Initialize the default input/output functions for the PNG file. If you
* use your own read or write routines, you can call either png_set_read_fn()
* or png_set_write_fn() instead of png_init_io(). If you have defined
* PNG_NO_STDIO or otherwise disabled PNG_STDIO_SUPPORTED, you must use a
* function of your own because "FILE *" isn't necessarily available.
*/
void PNGAPI
png_init_io(png_structrp png_ptr, png_FILE_p fp)
{
png_debug(1, "in png_init_io");
if (png_ptr == NULL)
return;
png_ptr->io_ptr = (png_voidp)fp;
}
# endif
#ifdef PNG_SAVE_INT_32_SUPPORTED
/* The png_save_int_32 function assumes integers are stored in two's
* complement format. If this isn't the case, then this routine needs to
* be modified to write data in two's complement format. Note that,
* the following works correctly even if png_int_32 has more than 32 bits
* (compare the more complex code required on read for sign extension.)
*/
void PNGAPI
png_save_int_32(png_bytep buf, png_int_32 i)
{
buf[0] = (png_byte)((i >> 24) & 0xff);
buf[1] = (png_byte)((i >> 16) & 0xff);
buf[2] = (png_byte)((i >> 8) & 0xff);
buf[3] = (png_byte)(i & 0xff);
}
#endif
# ifdef PNG_TIME_RFC1123_SUPPORTED
/* Convert the supplied time into an RFC 1123 string suitable for use in
* a "Creation Time" or other text-based time string.
*/
int PNGAPI
png_convert_to_rfc1123_buffer(char out[29], png_const_timep ptime)
{
static PNG_CONST char short_months[12][4] =
{"Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
if (out == NULL)
return 0;
if (ptime->year > 9999 /* RFC1123 limitation */ ||
ptime->month == 0 || ptime->month > 12 ||
ptime->day == 0 || ptime->day > 31 ||
ptime->hour > 23 || ptime->minute > 59 ||
ptime->second > 60)
return 0;
{
size_t pos = 0;
char number_buf[5]; /* enough for a four-digit year */
# define APPEND_STRING(string) pos = png_safecat(out, 29, pos, (string))
# define APPEND_NUMBER(format, value)\
APPEND_STRING(PNG_FORMAT_NUMBER(number_buf, format, (value)))
# define APPEND(ch) if (pos < 28) out[pos++] = (ch)
APPEND_NUMBER(PNG_NUMBER_FORMAT_u, (unsigned)ptime->day);
APPEND(' ');
APPEND_STRING(short_months[(ptime->month - 1)]);
APPEND(' ');
APPEND_NUMBER(PNG_NUMBER_FORMAT_u, ptime->year);
APPEND(' ');
src/Source/LibPNG/png.c view on Meta::CPAN
# undef APPEND
# undef APPEND_NUMBER
# undef APPEND_STRING
}
return 1;
}
# if PNG_LIBPNG_VER < 10700
/* To do: remove the following from libpng-1.7 */
/* Original API that uses a private buffer in png_struct.
* Deprecated because it causes png_struct to carry a spurious temporary
* buffer (png_struct::time_buffer), better to have the caller pass this in.
*/
png_const_charp PNGAPI
png_convert_to_rfc1123(png_structrp png_ptr, png_const_timep ptime)
{
if (png_ptr != NULL)
{
/* The only failure above if png_ptr != NULL is from an invalid ptime */
if (png_convert_to_rfc1123_buffer(png_ptr->time_buffer, ptime) == 0)
png_warning(png_ptr, "Ignoring invalid time value");
else
return png_ptr->time_buffer;
}
return NULL;
}
# endif
# endif /* TIME_RFC1123 */
#endif /* READ || WRITE */
png_const_charp PNGAPI
png_get_copyright(png_const_structrp png_ptr)
{
PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
#ifdef PNG_STRING_COPYRIGHT
return PNG_STRING_COPYRIGHT
#else
# ifdef __STDC__
return PNG_STRING_NEWLINE \
"libpng version 1.6.16 - December 22, 2014" PNG_STRING_NEWLINE \
"Copyright (c) 1998-2014 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
"Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
"Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
PNG_STRING_NEWLINE;
# else
return "libpng version 1.6.16 - December 22, 2014\
Copyright (c) 1998-2014 Glenn Randers-Pehrson\
Copyright (c) 1996-1997 Andreas Dilger\
Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
# endif
#endif
}
/* The following return the library version as a short string in the
* format 1.0.0 through 99.99.99zz. To get the version of *.h files
* used with your application, print out PNG_LIBPNG_VER_STRING, which
* is defined in png.h.
* Note: now there is no difference between png_get_libpng_ver() and
* png_get_header_ver(). Due to the version_nn_nn_nn typedef guard,
* it is guaranteed that png.c uses the correct version of png.h.
*/
png_const_charp PNGAPI
png_get_libpng_ver(png_const_structrp png_ptr)
{
/* Version of *.c files used when building libpng */
return png_get_header_ver(png_ptr);
}
png_const_charp PNGAPI
png_get_header_ver(png_const_structrp png_ptr)
{
/* Version of *.h files used when building libpng */
PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
return PNG_LIBPNG_VER_STRING;
}
png_const_charp PNGAPI
png_get_header_version(png_const_structrp png_ptr)
{
/* Returns longer string containing both version and date */
PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */
#ifdef __STDC__
return PNG_HEADER_VERSION_STRING
# ifndef PNG_READ_SUPPORTED
" (NO READ SUPPORT)"
# endif
PNG_STRING_NEWLINE;
#else
return PNG_HEADER_VERSION_STRING;
#endif
}
#ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
/* NOTE: this routine is not used internally! */
/* Build a grayscale palette. Palette is assumed to be 1 << bit_depth
* large of png_color. This lets grayscale images be treated as
* paletted. Most useful for gamma correction and simplification
* of code. This API is not used internally.
*/
void PNGAPI
png_build_grayscale_palette(int bit_depth, png_colorp palette)
{
int num_palette;
int color_inc;
int i;
int v;
png_debug(1, "in png_do_build_grayscale_palette");
if (palette == NULL)
return;
switch (bit_depth)
{
case 1:
num_palette = 2;
color_inc = 0xff;
break;
src/Source/LibPNG/png.c view on Meta::CPAN
break;
default:
num_palette = 0;
color_inc = 0;
break;
}
for (i = 0, v = 0; i < num_palette; i++, v += color_inc)
{
palette[i].red = (png_byte)v;
palette[i].green = (png_byte)v;
palette[i].blue = (png_byte)v;
}
}
#endif
#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
int PNGAPI
png_handle_as_unknown(png_const_structrp png_ptr, png_const_bytep chunk_name)
{
/* Check chunk_name and return "keep" value if it's on the list, else 0 */
png_const_bytep p, p_end;
if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list == 0)
return PNG_HANDLE_CHUNK_AS_DEFAULT;
p_end = png_ptr->chunk_list;
p = p_end + png_ptr->num_chunk_list*5; /* beyond end */
/* The code is the fifth byte after each four byte string. Historically this
* code was always searched from the end of the list, this is no longer
* necessary because the 'set' routine handles duplicate entries correcty.
*/
do /* num_chunk_list > 0, so at least one */
{
p -= 5;
if (memcmp(chunk_name, p, 4) == 0)
return p[4];
}
while (p > p_end);
/* This means that known chunks should be processed and unknown chunks should
* be handled according to the value of png_ptr->unknown_default; this can be
* confusing because, as a result, there are two levels of defaulting for
* unknown chunks.
*/
return PNG_HANDLE_CHUNK_AS_DEFAULT;
}
#if defined(PNG_READ_UNKNOWN_CHUNKS_SUPPORTED) ||\
defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
int /* PRIVATE */
png_chunk_unknown_handling(png_const_structrp png_ptr, png_uint_32 chunk_name)
{
png_byte chunk_string[5];
PNG_CSTRING_FROM_CHUNK(chunk_string, chunk_name);
return png_handle_as_unknown(png_ptr, chunk_string);
}
#endif /* READ_UNKNOWN_CHUNKS || HANDLE_AS_UNKNOWN */
#endif /* SET_UNKNOWN_CHUNKS */
#ifdef PNG_READ_SUPPORTED
/* This function, added to libpng-1.0.6g, is untested. */
int PNGAPI
png_reset_zstream(png_structrp png_ptr)
{
if (png_ptr == NULL)
return Z_STREAM_ERROR;
/* WARNING: this resets the window bits to the maximum! */
return (inflateReset(&png_ptr->zstream));
}
#endif /* READ */
/* This function was added to libpng-1.0.7 */
png_uint_32 PNGAPI
png_access_version_number(void)
{
/* Version of *.c files used when building libpng */
return((png_uint_32)PNG_LIBPNG_VER);
}
#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
/* Ensure that png_ptr->zstream.msg holds some appropriate error message string.
* If it doesn't 'ret' is used to set it to something appropriate, even in cases
* like Z_OK or Z_STREAM_END where the error code is apparently a success code.
*/
void /* PRIVATE */
png_zstream_error(png_structrp png_ptr, int ret)
{
/* Translate 'ret' into an appropriate error string, priority is given to the
* one in zstream if set. This always returns a string, even in cases like
* Z_OK or Z_STREAM_END where the error code is a success code.
*/
if (png_ptr->zstream.msg == NULL) switch (ret)
{
default:
case Z_OK:
png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return code");
break;
case Z_STREAM_END:
/* Normal exit */
png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected end of LZ stream");
break;
case Z_NEED_DICT:
/* This means the deflate stream did not have a dictionary; this
* indicates a bogus PNG.
*/
png_ptr->zstream.msg = PNGZ_MSG_CAST("missing LZ dictionary");
break;
case Z_ERRNO:
/* gz APIs only: should not happen */
png_ptr->zstream.msg = PNGZ_MSG_CAST("zlib IO error");
break;
case Z_STREAM_ERROR:
/* internal libpng error */
png_ptr->zstream.msg = PNGZ_MSG_CAST("bad parameters to zlib");
break;
case Z_DATA_ERROR:
png_ptr->zstream.msg = PNGZ_MSG_CAST("damaged LZ stream");
break;
case Z_MEM_ERROR:
png_ptr->zstream.msg = PNGZ_MSG_CAST("insufficient memory");
break;
case Z_BUF_ERROR:
/* End of input or output; not a problem if the caller is doing
* incremental read or write.
*/
png_ptr->zstream.msg = PNGZ_MSG_CAST("truncated");
break;
case Z_VERSION_ERROR:
png_ptr->zstream.msg = PNGZ_MSG_CAST("unsupported zlib version");
break;
case PNG_UNEXPECTED_ZLIB_RETURN:
/* Compile errors here mean that zlib now uses the value co-opted in
* pngpriv.h for PNG_UNEXPECTED_ZLIB_RETURN; update the switch above
* and change pngpriv.h. Note that this message is "... return",
* whereas the default/Z_OK one is "... return code".
*/
png_ptr->zstream.msg = PNGZ_MSG_CAST("unexpected zlib return");
break;
}
}
/* png_convert_size: a PNGAPI but no longer in png.h, so deleted
* at libpng 1.5.5!
*/
/* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */
#ifdef PNG_GAMMA_SUPPORTED /* always set if COLORSPACE */
static int
png_colorspace_check_gamma(png_const_structrp png_ptr,
png_colorspacerp colorspace, png_fixed_point gAMA, int from)
/* This is called to check a new gamma value against an existing one. The
* routine returns false if the new gamma value should not be written.
*
* 'from' says where the new gamma value comes from:
*
* 0: the new gamma value is the libpng estimate for an ICC profile
* 1: the new gamma value comes from a gAMA chunk
* 2: the new gamma value comes from an sRGB chunk
*/
{
png_fixed_point gtest;
if ((colorspace->flags & PNG_COLORSPACE_HAVE_GAMMA) != 0 &&
(png_muldiv(>est, colorspace->gamma, PNG_FP_1, gAMA) == 0 ||
png_gamma_significant(gtest) != 0))
{
/* Either this is an sRGB image, in which case the calculated gamma
* approximation should match, or this is an image with a profile and the
* value libpng calculates for the gamma of the profile does not match the
* value recorded in the file. The former, sRGB, case is an error, the
* latter is just a warning.
*/
if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0 || from == 2)
{
png_chunk_report(png_ptr, "gamma value does not match sRGB",
PNG_CHUNK_ERROR);
/* Do not overwrite an sRGB value */
return from == 2;
}
else /* sRGB tag not involved */
{
png_chunk_report(png_ptr, "gamma value does not match libpng estimate",
PNG_CHUNK_WARNING);
return from == 1;
}
}
return 1;
}
void /* PRIVATE */
png_colorspace_set_gamma(png_const_structrp png_ptr,
png_colorspacerp colorspace, png_fixed_point gAMA)
{
/* Changed in libpng-1.5.4 to limit the values to ensure overflow can't
* occur. Since the fixed point representation is asymetrical it is
* possible for 1/gamma to overflow the limit of 21474 and this means the
* gamma value must be at least 5/100000 and hence at most 20000.0. For
* safety the limits here are a little narrower. The values are 0.00016 to
* 6250.0, which are truly ridiculous gamma values (and will produce
* displays that are all black or all white.)
*
* In 1.6.0 this test replaces the ones in pngrutil.c, in the gAMA chunk
* handling code, which only required the value to be >0.
*/
png_const_charp errmsg;
if (gAMA < 16 || gAMA > 625000000)
errmsg = "gamma value out of range";
# ifdef PNG_READ_gAMA_SUPPORTED
/* Allow the application to set the gamma value more than once */
else if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
(colorspace->flags & PNG_COLORSPACE_FROM_gAMA) != 0)
errmsg = "duplicate";
# endif
/* Do nothing if the colorspace is already invalid */
else if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
return;
else
{
if (png_colorspace_check_gamma(png_ptr, colorspace, gAMA,
1/*from gAMA*/) != 0)
{
/* Store this gamma value. */
colorspace->gamma = gAMA;
colorspace->flags |=
(PNG_COLORSPACE_HAVE_GAMMA | PNG_COLORSPACE_FROM_gAMA);
}
/* At present if the check_gamma test fails the gamma of the colorspace is
* not updated however the colorspace is not invalidated. This
* corresponds to the case where the existing gamma comes from an sRGB
* chunk or profile. An error message has already been output.
*/
return;
}
/* Error exit - errmsg has been set. */
colorspace->flags |= PNG_COLORSPACE_INVALID;
png_chunk_report(png_ptr, errmsg, PNG_CHUNK_WRITE_ERROR);
}
void /* PRIVATE */
png_colorspace_sync_info(png_const_structrp png_ptr, png_inforp info_ptr)
{
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_INVALID) != 0)
{
/* Everything is invalid */
info_ptr->valid &= ~(PNG_INFO_gAMA|PNG_INFO_cHRM|PNG_INFO_sRGB|
PNG_INFO_iCCP);
# ifdef PNG_COLORSPACE_SUPPORTED
/* Clean up the iCCP profile now if it won't be used. */
png_free_data(png_ptr, info_ptr, PNG_FREE_ICCP, -1/*not used*/);
# else
PNG_UNUSED(png_ptr)
# endif
}
else
{
# ifdef PNG_COLORSPACE_SUPPORTED
/* Leave the INFO_iCCP flag set if the pngset.c code has already set
* it; this allows a PNG to contain a profile which matches sRGB and
* yet still have that profile retrievable by the application.
*/
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_MATCHES_sRGB) != 0)
info_ptr->valid |= PNG_INFO_sRGB;
else
info_ptr->valid &= ~PNG_INFO_sRGB;
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
src/Source/LibPNG/png.c view on Meta::CPAN
if ((info_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_GAMMA) != 0)
info_ptr->valid |= PNG_INFO_gAMA;
else
info_ptr->valid &= ~PNG_INFO_gAMA;
}
}
#ifdef PNG_READ_SUPPORTED
void /* PRIVATE */
png_colorspace_sync(png_const_structrp png_ptr, png_inforp info_ptr)
{
if (info_ptr == NULL) /* reduce code size; check here not in the caller */
return;
info_ptr->colorspace = png_ptr->colorspace;
png_colorspace_sync_info(png_ptr, info_ptr);
}
#endif
#endif
#ifdef PNG_COLORSPACE_SUPPORTED
/* Added at libpng-1.5.5 to support read and write of true CIEXYZ values for
* cHRM, as opposed to using chromaticities. These internal APIs return
* non-zero on a parameter error. The X, Y and Z values are required to be
* positive and less than 1.0.
*/
static int
png_xy_from_XYZ(png_xy *xy, const png_XYZ *XYZ)
{
png_int_32 d, dwhite, whiteX, whiteY;
d = XYZ->red_X + XYZ->red_Y + XYZ->red_Z;
if (png_muldiv(&xy->redx, XYZ->red_X, PNG_FP_1, d) == 0)
return 1;
if (png_muldiv(&xy->redy, XYZ->red_Y, PNG_FP_1, d) == 0)
return 1;
dwhite = d;
whiteX = XYZ->red_X;
whiteY = XYZ->red_Y;
d = XYZ->green_X + XYZ->green_Y + XYZ->green_Z;
if (png_muldiv(&xy->greenx, XYZ->green_X, PNG_FP_1, d) == 0)
return 1;
if (png_muldiv(&xy->greeny, XYZ->green_Y, PNG_FP_1, d) == 0)
return 1;
dwhite += d;
whiteX += XYZ->green_X;
whiteY += XYZ->green_Y;
d = XYZ->blue_X + XYZ->blue_Y + XYZ->blue_Z;
if (png_muldiv(&xy->bluex, XYZ->blue_X, PNG_FP_1, d) == 0)
return 1;
if (png_muldiv(&xy->bluey, XYZ->blue_Y, PNG_FP_1, d) == 0)
return 1;
dwhite += d;
whiteX += XYZ->blue_X;
whiteY += XYZ->blue_Y;
/* The reference white is simply the sum of the end-point (X,Y,Z) vectors,
* thus:
*/
if (png_muldiv(&xy->whitex, whiteX, PNG_FP_1, dwhite) == 0)
return 1;
if (png_muldiv(&xy->whitey, whiteY, PNG_FP_1, dwhite) == 0)
return 1;
return 0;
}
static int
png_XYZ_from_xy(png_XYZ *XYZ, const png_xy *xy)
{
png_fixed_point red_inverse, green_inverse, blue_scale;
png_fixed_point left, right, denominator;
/* Check xy and, implicitly, z. Note that wide gamut color spaces typically
* have end points with 0 tristimulus values (these are impossible end
* points, but they are used to cover the possible colors.)
*/
if (xy->redx < 0 || xy->redx > PNG_FP_1) return 1;
if (xy->redy < 0 || xy->redy > PNG_FP_1-xy->redx) return 1;
if (xy->greenx < 0 || xy->greenx > PNG_FP_1) return 1;
if (xy->greeny < 0 || xy->greeny > PNG_FP_1-xy->greenx) return 1;
if (xy->bluex < 0 || xy->bluex > PNG_FP_1) return 1;
src/Source/LibPNG/png.c view on Meta::CPAN
* and it is certain that it becomes unstable where the end points are close
* together.
*
* So this code uses the perhaps slightly less optimal but more
* understandable and totally obvious approach of calculating color-scale.
*
* This algorithm depends on the precision in white-scale and that is
* (1/white-y), so we can immediately see that as white-y approaches 0 the
* accuracy inherent in the cHRM chunk drops off substantially.
*
* libpng arithmetic: a simple inversion of the above equations
* ------------------------------------------------------------
*
* white_scale = 1/white-y
* white-X = white-x * white-scale
* white-Y = 1.0
* white-Z = (1 - white-x - white-y) * white_scale
*
* white-C = red-C + green-C + blue-C
* = red-c*red-scale + green-c*green-scale + blue-c*blue-scale
*
src/Source/LibPNG/png.c view on Meta::CPAN
* = (1 - white-x - white-y)/white-y
*
* In the last equation color-z is (1 - color-x - color-y) so we can add all
* three equations together to get an alternative third:
*
* red-scale + green-scale + blue-scale = 1/white-y = white-scale
*
* So now we have a Cramer's rule solution where the determinants are just
* 3x3 - far more tractible. Unfortunately 3x3 determinants still involve
* multiplication of three coefficients so we can't guarantee to avoid
* overflow in the libpng fixed point representation. Using Cramer's rule in
* floating point is probably a good choice here, but it's not an option for
* fixed point. Instead proceed to simplify the first two equations by
* eliminating what is likely to be the largest value, blue-scale:
*
* blue-scale = white-scale - red-scale - green-scale
*
* Hence:
*
* (red-x - blue-x)*red-scale + (green-x - blue-x)*green-scale =
* (white-x - blue-x)*white-scale
src/Source/LibPNG/png.c view on Meta::CPAN
* Kodak ProPhoto
* 0.288071128229293 0.711843217810102 0.000085653960605
* Adobe RGB
* 0.297344975250536 0.627363566255466 0.075291458493998
* Adobe Wide Gamut RGB
* 0.258728243040113 0.724682314948566 0.016589442011321
*/
/* By the argument, above overflow should be impossible here. The return
* value of 2 indicates an internal error to the caller.
*/
if (png_muldiv(&left, xy->greenx-xy->bluex, xy->redy - xy->bluey, 7) == 0)
return 2;
if (png_muldiv(&right, xy->greeny-xy->bluey, xy->redx - xy->bluex, 7) == 0)
return 2;
denominator = left - right;
/* Now find the red numerator. */
if (png_muldiv(&left, xy->greenx-xy->bluex, xy->whitey-xy->bluey, 7) == 0)
return 2;
if (png_muldiv(&right, xy->greeny-xy->bluey, xy->whitex-xy->bluex, 7) == 0)
return 2;
/* Overflow is possible here and it indicates an extreme set of PNG cHRM
* chunk values. This calculation actually returns the reciprocal of the
* scale value because this allows us to delay the multiplication of white-y
* into the denominator, which tends to produce a small number.
*/
if (png_muldiv(&red_inverse, xy->whitey, denominator, left-right) == 0 ||
red_inverse <= xy->whitey /* r+g+b scales = white scale */)
return 1;
/* Similarly for green_inverse: */
if (png_muldiv(&left, xy->redy-xy->bluey, xy->whitex-xy->bluex, 7) == 0)
return 2;
if (png_muldiv(&right, xy->redx-xy->bluex, xy->whitey-xy->bluey, 7) == 0)
return 2;
if (png_muldiv(&green_inverse, xy->whitey, denominator, left-right) == 0 ||
green_inverse <= xy->whitey)
return 1;
/* And the blue scale, the checks above guarantee this can't overflow but it
* can still produce 0 for extreme cHRM values.
*/
blue_scale = png_reciprocal(xy->whitey) - png_reciprocal(red_inverse) -
png_reciprocal(green_inverse);
if (blue_scale <= 0)
return 1;
/* And fill in the png_XYZ: */
if (png_muldiv(&XYZ->red_X, xy->redx, PNG_FP_1, red_inverse) == 0)
return 1;
if (png_muldiv(&XYZ->red_Y, xy->redy, PNG_FP_1, red_inverse) == 0)
return 1;
if (png_muldiv(&XYZ->red_Z, PNG_FP_1 - xy->redx - xy->redy, PNG_FP_1,
red_inverse) == 0)
return 1;
if (png_muldiv(&XYZ->green_X, xy->greenx, PNG_FP_1, green_inverse) == 0)
return 1;
if (png_muldiv(&XYZ->green_Y, xy->greeny, PNG_FP_1, green_inverse) == 0)
return 1;
if (png_muldiv(&XYZ->green_Z, PNG_FP_1 - xy->greenx - xy->greeny, PNG_FP_1,
green_inverse) == 0)
return 1;
if (png_muldiv(&XYZ->blue_X, xy->bluex, blue_scale, PNG_FP_1) == 0)
return 1;
if (png_muldiv(&XYZ->blue_Y, xy->bluey, blue_scale, PNG_FP_1) == 0)
return 1;
if (png_muldiv(&XYZ->blue_Z, PNG_FP_1 - xy->bluex - xy->bluey, blue_scale,
PNG_FP_1) == 0)
return 1;
return 0; /*success*/
}
static int
png_XYZ_normalize(png_XYZ *XYZ)
{
png_int_32 Y;
if (XYZ->red_Y < 0 || XYZ->green_Y < 0 || XYZ->blue_Y < 0 ||
XYZ->red_X < 0 || XYZ->green_X < 0 || XYZ->blue_X < 0 ||
XYZ->red_Z < 0 || XYZ->green_Z < 0 || XYZ->blue_Z < 0)
return 1;
/* Normalize by scaling so the sum of the end-point Y values is PNG_FP_1.
* IMPLEMENTATION NOTE: ANSI requires signed overflow not to occur, therefore
* relying on addition of two positive values producing a negative one is not
* safe.
src/Source/LibPNG/png.c view on Meta::CPAN
Y = XYZ->red_Y;
if (0x7fffffff - Y < XYZ->green_X)
return 1;
Y += XYZ->green_Y;
if (0x7fffffff - Y < XYZ->blue_X)
return 1;
Y += XYZ->blue_Y;
if (Y != PNG_FP_1)
{
if (png_muldiv(&XYZ->red_X, XYZ->red_X, PNG_FP_1, Y) == 0)
return 1;
if (png_muldiv(&XYZ->red_Y, XYZ->red_Y, PNG_FP_1, Y) == 0)
return 1;
if (png_muldiv(&XYZ->red_Z, XYZ->red_Z, PNG_FP_1, Y) == 0)
return 1;
if (png_muldiv(&XYZ->green_X, XYZ->green_X, PNG_FP_1, Y) == 0)
return 1;
if (png_muldiv(&XYZ->green_Y, XYZ->green_Y, PNG_FP_1, Y) == 0)
return 1;
if (png_muldiv(&XYZ->green_Z, XYZ->green_Z, PNG_FP_1, Y) == 0)
return 1;
if (png_muldiv(&XYZ->blue_X, XYZ->blue_X, PNG_FP_1, Y) == 0)
return 1;
if (png_muldiv(&XYZ->blue_Y, XYZ->blue_Y, PNG_FP_1, Y) == 0)
return 1;
if (png_muldiv(&XYZ->blue_Z, XYZ->blue_Z, PNG_FP_1, Y) == 0)
return 1;
}
return 0;
}
static int
png_colorspace_endpoints_match(const png_xy *xy1, const png_xy *xy2, int delta)
{
/* Allow an error of +/-0.01 (absolute value) on each chromaticity */
if (PNG_OUT_OF_RANGE(xy1->whitex, xy2->whitex,delta) ||
PNG_OUT_OF_RANGE(xy1->whitey, xy2->whitey,delta) ||
PNG_OUT_OF_RANGE(xy1->redx, xy2->redx, delta) ||
PNG_OUT_OF_RANGE(xy1->redy, xy2->redy, delta) ||
PNG_OUT_OF_RANGE(xy1->greenx, xy2->greenx,delta) ||
PNG_OUT_OF_RANGE(xy1->greeny, xy2->greeny,delta) ||
PNG_OUT_OF_RANGE(xy1->bluex, xy2->bluex, delta) ||
PNG_OUT_OF_RANGE(xy1->bluey, xy2->bluey, delta))
return 0;
return 1;
}
/* Added in libpng-1.6.0, a different check for the validity of a set of cHRM
* chunk chromaticities. Earlier checks used to simply look for the overflow
* condition (where the determinant of the matrix to solve for XYZ ends up zero
* because the chromaticity values are not all distinct.) Despite this it is
* theoretically possible to produce chromaticities that are apparently valid
* but that rapidly degrade to invalid, potentially crashing, sets because of
* arithmetic inaccuracies when calculations are performed on them. The new
* check is to round-trip xy -> XYZ -> xy and then check that the result is
* within a small percentage of the original.
*/
static int
png_colorspace_check_xy(png_XYZ *XYZ, const png_xy *xy)
{
int result;
png_xy xy_test;
/* As a side-effect this routine also returns the XYZ endpoints. */
result = png_XYZ_from_xy(XYZ, xy);
if (result != 0)
return result;
result = png_xy_from_XYZ(&xy_test, XYZ);
if (result != 0)
return result;
if (png_colorspace_endpoints_match(xy, &xy_test,
5/*actually, the math is pretty accurate*/) != 0)
return 0;
/* Too much slip */
return 1;
}
/* This is the check going the other way. The XYZ is modified to normalize it
* (another side-effect) and the xy chromaticities are returned.
*/
static int
png_colorspace_check_XYZ(png_xy *xy, png_XYZ *XYZ)
{
int result;
png_XYZ XYZtemp;
result = png_XYZ_normalize(XYZ);
if (result != 0)
return result;
result = png_xy_from_XYZ(xy, XYZ);
if (result != 0)
return result;
XYZtemp = *XYZ;
return png_colorspace_check_xy(&XYZtemp, xy);
}
/* Used to check for an endpoint match against sRGB */
static const png_xy sRGB_xy = /* From ITU-R BT.709-3 */
{
/* color x y */
/* red */ 64000, 33000,
/* green */ 30000, 60000,
/* blue */ 15000, 6000,
/* white */ 31270, 32900
};
static int
png_colorspace_set_xy_and_XYZ(png_const_structrp png_ptr,
png_colorspacerp colorspace, const png_xy *xy, const png_XYZ *XYZ,
int preferred)
{
if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
return 0;
/* The consistency check is performed on the chromaticities; this factors out
* variations because of the normalization (or not) of the end point Y
* values.
*/
if (preferred < 2 &&
(colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
{
/* The end points must be reasonably close to any we already have. The
* following allows an error of up to +/-.001
*/
if (png_colorspace_endpoints_match(xy, &colorspace->end_points_xy,
100) == 0)
{
colorspace->flags |= PNG_COLORSPACE_INVALID;
png_benign_error(png_ptr, "inconsistent chromaticities");
return 0; /* failed */
}
/* Only overwrite with preferred values */
if (preferred == 0)
return 1; /* ok, but no change */
}
colorspace->end_points_xy = *xy;
colorspace->end_points_XYZ = *XYZ;
colorspace->flags |= PNG_COLORSPACE_HAVE_ENDPOINTS;
/* The end points are normally quoted to two decimal digits, so allow +/-0.01
* on this test.
*/
if (png_colorspace_endpoints_match(xy, &sRGB_xy, 1000) != 0)
colorspace->flags |= PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB;
else
colorspace->flags &= PNG_COLORSPACE_CANCEL(
PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
return 2; /* ok and changed */
}
int /* PRIVATE */
png_colorspace_set_chromaticities(png_const_structrp png_ptr,
png_colorspacerp colorspace, const png_xy *xy, int preferred)
{
/* We must check the end points to ensure they are reasonable - in the past
* color management systems have crashed as a result of getting bogus
* colorant values, while this isn't the fault of libpng it is the
* responsibility of libpng because PNG carries the bomb and libpng is in a
* position to protect against it.
*/
png_XYZ XYZ;
switch (png_colorspace_check_xy(&XYZ, xy))
{
case 0: /* success */
return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, xy, &XYZ,
preferred);
case 1:
/* We can't invert the chromaticities so we can't produce value XYZ
* values. Likely as not a color management system will fail too.
*/
colorspace->flags |= PNG_COLORSPACE_INVALID;
png_benign_error(png_ptr, "invalid chromaticities");
break;
default:
/* libpng is broken; this should be a warning but if it happens we
* want error reports so for the moment it is an error.
*/
colorspace->flags |= PNG_COLORSPACE_INVALID;
png_error(png_ptr, "internal error checking chromaticities");
break;
}
return 0; /* failed */
}
int /* PRIVATE */
png_colorspace_set_endpoints(png_const_structrp png_ptr,
png_colorspacerp colorspace, const png_XYZ *XYZ_in, int preferred)
{
png_XYZ XYZ = *XYZ_in;
png_xy xy;
switch (png_colorspace_check_XYZ(&xy, &XYZ))
{
case 0:
return png_colorspace_set_xy_and_XYZ(png_ptr, colorspace, &xy, &XYZ,
preferred);
case 1:
/* End points are invalid. */
colorspace->flags |= PNG_COLORSPACE_INVALID;
png_benign_error(png_ptr, "invalid end points");
break;
default:
colorspace->flags |= PNG_COLORSPACE_INVALID;
png_error(png_ptr, "internal error checking chromaticities");
break;
}
return 0; /* failed */
}
#if defined(PNG_sRGB_SUPPORTED) || defined(PNG_iCCP_SUPPORTED)
/* Error message generation */
static char
png_icc_tag_char(png_uint_32 byte)
{
byte &= 0xff;
if (byte >= 32 && byte <= 126)
return (char)byte;
else
return '?';
}
static void
png_icc_tag_name(char *name, png_uint_32 tag)
{
name[0] = '\'';
name[1] = png_icc_tag_char(tag >> 24);
name[2] = png_icc_tag_char(tag >> 16);
name[3] = png_icc_tag_char(tag >> 8);
name[4] = png_icc_tag_char(tag );
name[5] = '\'';
}
static int
is_ICC_signature_char(png_alloc_size_t it)
{
return it == 32 || (it >= 48 && it <= 57) || (it >= 65 && it <= 90) ||
(it >= 97 && it <= 122);
}
static int
is_ICC_signature(png_alloc_size_t it)
{
return is_ICC_signature_char(it >> 24) /* checks all the top bits */ &&
is_ICC_signature_char((it >> 16) & 0xff) &&
is_ICC_signature_char((it >> 8) & 0xff) &&
is_ICC_signature_char(it & 0xff);
}
static int
png_icc_profile_error(png_const_structrp png_ptr, png_colorspacerp colorspace,
png_const_charp name, png_alloc_size_t value, png_const_charp reason)
{
size_t pos;
char message[196]; /* see below for calculation */
if (colorspace != NULL)
colorspace->flags |= PNG_COLORSPACE_INVALID;
pos = png_safecat(message, (sizeof message), 0, "profile '"); /* 9 chars */
pos = png_safecat(message, pos+79, pos, name); /* Truncate to 79 chars */
pos = png_safecat(message, (sizeof message), pos, "': "); /* +2 = 90 */
if (is_ICC_signature(value) != 0)
{
/* So 'value' is at most 4 bytes and the following cast is safe */
png_icc_tag_name(message+pos, (png_uint_32)value);
pos += 6; /* total +8; less than the else clause */
message[pos++] = ':';
message[pos++] = ' ';
}
# ifdef PNG_WARNINGS_SUPPORTED
else
{
char number[PNG_NUMBER_BUFFER_SIZE]; /* +24 = 114*/
pos = png_safecat(message, (sizeof message), pos,
png_format_number(number, number+(sizeof number),
PNG_NUMBER_FORMAT_x, value));
pos = png_safecat(message, (sizeof message), pos, "h: "); /*+2 = 116*/
}
# endif
/* The 'reason' is an arbitrary message, allow +79 maximum 195 */
pos = png_safecat(message, (sizeof message), pos, reason);
PNG_UNUSED(pos)
/* This is recoverable, but make it unconditionally an app_error on write to
* avoid writing invalid ICC profiles into PNG files (i.e., we handle them
* on read, with a warning, but on write unless the app turns off
* application errors the PNG won't be written.)
*/
png_chunk_report(png_ptr, message,
(colorspace != NULL) ? PNG_CHUNK_ERROR : PNG_CHUNK_WRITE_ERROR);
return 0;
}
#endif /* sRGB || iCCP */
#ifdef PNG_sRGB_SUPPORTED
int /* PRIVATE */
png_colorspace_set_sRGB(png_const_structrp png_ptr, png_colorspacerp colorspace,
int intent)
{
/* sRGB sets known gamma, end points and (from the chunk) intent. */
/* IMPORTANT: these are not necessarily the values found in an ICC profile
* because ICC profiles store values adapted to a D50 environment; it is
* expected that the ICC profile mediaWhitePointTag will be D50; see the
* checks and code elsewhere to understand this better.
*
* These XYZ values, which are accurate to 5dp, produce rgb to gray
* coefficients of (6968,23435,2366), which are reduced (because they add up
* to 32769 not 32768) to (6968,23434,2366). These are the values that
* libpng has traditionally used (and are the best values given the 15bit
* algorithm used by the rgb to gray code.)
*/
static const png_XYZ sRGB_XYZ = /* D65 XYZ (*not* the D50 adapted values!) */
{
/* color X Y Z */
/* red */ 41239, 21264, 1933,
/* green */ 35758, 71517, 11919,
/* blue */ 18048, 7219, 95053
};
/* Do nothing if the colorspace is already invalidated. */
if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
return 0;
src/Source/LibPNG/png.c view on Meta::CPAN
/* Check the intent, then check for existing settings. It is valid for the
* PNG file to have cHRM or gAMA chunks along with sRGB, but the values must
* be consistent with the correct values. If, however, this function is
* called below because an iCCP chunk matches sRGB then it is quite
* conceivable that an older app recorded incorrect gAMA and cHRM because of
* an incorrect calculation based on the values in the profile - this does
* *not* invalidate the profile (though it still produces an error, which can
* be ignored.)
*/
if (intent < 0 || intent >= PNG_sRGB_INTENT_LAST)
return png_icc_profile_error(png_ptr, colorspace, "sRGB",
(unsigned)intent, "invalid sRGB rendering intent");
if ((colorspace->flags & PNG_COLORSPACE_HAVE_INTENT) != 0 &&
colorspace->rendering_intent != intent)
return png_icc_profile_error(png_ptr, colorspace, "sRGB",
(unsigned)intent, "inconsistent rendering intents");
if ((colorspace->flags & PNG_COLORSPACE_FROM_sRGB) != 0)
{
png_benign_error(png_ptr, "duplicate sRGB information ignored");
return 0;
}
/* If the standard sRGB cHRM chunk does not match the one from the PNG file
* warn but overwrite the value with the correct one.
*/
if ((colorspace->flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0 &&
!png_colorspace_endpoints_match(&sRGB_xy, &colorspace->end_points_xy,
100))
png_chunk_report(png_ptr, "cHRM chunk does not match sRGB",
PNG_CHUNK_ERROR);
/* This check is just done for the error reporting - the routine always
* returns true when the 'from' argument corresponds to sRGB (2).
*/
(void)png_colorspace_check_gamma(png_ptr, colorspace, PNG_GAMMA_sRGB_INVERSE,
2/*from sRGB*/);
/* intent: bugs in GCC force 'int' to be used as the parameter type. */
colorspace->rendering_intent = (png_uint_16)intent;
colorspace->flags |= PNG_COLORSPACE_HAVE_INTENT;
/* endpoints */
colorspace->end_points_xy = sRGB_xy;
colorspace->end_points_XYZ = sRGB_XYZ;
colorspace->flags |=
(PNG_COLORSPACE_HAVE_ENDPOINTS|PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB);
/* gamma */
colorspace->gamma = PNG_GAMMA_sRGB_INVERSE;
src/Source/LibPNG/png.c view on Meta::CPAN
return 1; /* set */
}
#endif /* sRGB */
#ifdef PNG_iCCP_SUPPORTED
/* Encoded value of D50 as an ICC XYZNumber. From the ICC 2010 spec the value
* is XYZ(0.9642,1.0,0.8249), which scales to:
*
* (63189.8112, 65536, 54060.6464)
*/
static const png_byte D50_nCIEXYZ[12] =
{ 0x00, 0x00, 0xf6, 0xd6, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0xd3, 0x2d };
int /* PRIVATE */
png_icc_check_length(png_const_structrp png_ptr, png_colorspacerp colorspace,
png_const_charp name, png_uint_32 profile_length)
{
if (profile_length < 132)
return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
"too short");
return 1;
}
int /* PRIVATE */
png_icc_check_header(png_const_structrp png_ptr, png_colorspacerp colorspace,
png_const_charp name, png_uint_32 profile_length,
png_const_bytep profile/* first 132 bytes only */, int color_type)
{
png_uint_32 temp;
/* Length check; this cannot be ignored in this code because profile_length
* is used later to check the tag table, so even if the profile seems over
* long profile_length from the caller must be correct. The caller can fix
* this up on read or write by just passing in the profile header length.
*/
temp = png_get_uint_32(profile);
if (temp != profile_length)
return png_icc_profile_error(png_ptr, colorspace, name, temp,
"length does not match profile");
temp = (png_uint_32) (*(profile+8));
if (temp > 3 && (profile_length & 3))
return png_icc_profile_error(png_ptr, colorspace, name, profile_length,
"invalid length");
temp = png_get_uint_32(profile+128); /* tag count: 12 bytes/tag */
if (temp > 357913930 || /* (2^32-4-132)/12: maximum possible tag count */
profile_length < 132+12*temp) /* truncated tag table */
return png_icc_profile_error(png_ptr, colorspace, name, temp,
"tag count too large");
/* The 'intent' must be valid or we can't store it, ICC limits the intent to
* 16 bits.
*/
temp = png_get_uint_32(profile+64);
if (temp >= 0xffff) /* The ICC limit */
return png_icc_profile_error(png_ptr, colorspace, name, temp,
"invalid rendering intent");
/* This is just a warning because the profile may be valid in future
* versions.
*/
if (temp >= PNG_sRGB_INTENT_LAST)
(void)png_icc_profile_error(png_ptr, NULL, name, temp,
"intent outside defined range");
/* At this point the tag table can't be checked because it hasn't necessarily
* been loaded; however, various header fields can be checked. These checks
* are for values permitted by the PNG spec in an ICC profile; the PNG spec
* restricts the profiles that can be passed in an iCCP chunk (they must be
* appropriate to processing PNG data!)
*/
/* Data checks (could be skipped). These checks must be independent of the
* version number; however, the version number doesn't accomodate changes in
* the header fields (just the known tags and the interpretation of the
* data.)
*/
temp = png_get_uint_32(profile+36); /* signature 'ascp' */
if (temp != 0x61637370)
return png_icc_profile_error(png_ptr, colorspace, name, temp,
"invalid signature");
/* Currently the PCS illuminant/adopted white point (the computational
* white point) are required to be D50,
* however the profile contains a record of the illuminant so perhaps ICC
* expects to be able to change this in the future (despite the rationale in
* the introduction for using a fixed PCS adopted white.) Consequently the
* following is just a warning.
*/
if (memcmp(profile+68, D50_nCIEXYZ, 12) != 0)
(void)png_icc_profile_error(png_ptr, NULL, name, 0/*no tag value*/,
"PCS illuminant is not D50");
/* The PNG spec requires this:
* "If the iCCP chunk is present, the image samples conform to the colour
* space represented by the embedded ICC profile as defined by the
* International Color Consortium [ICC]. The colour space of the ICC profile
* shall be an RGB colour space for colour images (PNG colour types 2, 3, and
* 6), or a greyscale colour space for greyscale images (PNG colour types 0
* and 4)."
*
* This checking code ensures the embedded profile (on either read or write)
* conforms to the specification requirements. Notice that an ICC 'gray'
* color-space profile contains the information to transform the monochrome
* data to XYZ or L*a*b (according to which PCS the profile uses) and this
* should be used in preference to the standard libpng K channel replication
* into R, G and B channels.
*
* Previously it was suggested that an RGB profile on grayscale data could be
* handled. However it it is clear that using an RGB profile in this context
* must be an error - there is no specification of what it means. Thus it is
* almost certainly more correct to ignore the profile.
*/
temp = png_get_uint_32(profile+16); /* data colour space field */
switch (temp)
{
case 0x52474220: /* 'RGB ' */
if ((color_type & PNG_COLOR_MASK_COLOR) == 0)
return png_icc_profile_error(png_ptr, colorspace, name, temp,
"RGB color space not permitted on grayscale PNG");
break;
case 0x47524159: /* 'GRAY' */
if ((color_type & PNG_COLOR_MASK_COLOR) != 0)
return png_icc_profile_error(png_ptr, colorspace, name, temp,
"Gray color space not permitted on RGB PNG");
break;
default:
return png_icc_profile_error(png_ptr, colorspace, name, temp,
"invalid ICC profile color space");
}
/* It is up to the application to check that the profile class matches the
* application requirements; the spec provides no guidance, but it's pretty
* weird if the profile is not scanner ('scnr'), monitor ('mntr'), printer
* ('prtr') or 'spac' (for generic color spaces). Issue a warning in these
* cases. Issue an error for device link or abstract profiles - these don't
* contain the records necessary to transform the color-space to anything
* other than the target device (and not even that for an abstract profile).
* Profiles of these classes may not be embedded in images.
*/
temp = png_get_uint_32(profile+12); /* profile/device class */
switch (temp)
{
case 0x73636E72: /* 'scnr' */
case 0x6D6E7472: /* 'mntr' */
case 0x70727472: /* 'prtr' */
case 0x73706163: /* 'spac' */
/* All supported */
break;
case 0x61627374: /* 'abst' */
/* May not be embedded in an image */
return png_icc_profile_error(png_ptr, colorspace, name, temp,
"invalid embedded Abstract ICC profile");
case 0x6C696E6B: /* 'link' */
/* DeviceLink profiles cannot be interpreted in a non-device specific
* fashion, if an app uses the AToB0Tag in the profile the results are
* undefined unless the result is sent to the intended device,
* therefore a DeviceLink profile should not be found embedded in a
* PNG.
*/
return png_icc_profile_error(png_ptr, colorspace, name, temp,
"unexpected DeviceLink ICC profile class");
case 0x6E6D636C: /* 'nmcl' */
/* A NamedColor profile is also device specific, however it doesn't
* contain an AToB0 tag that is open to misinterpretation. Almost
* certainly it will fail the tests below.
*/
(void)png_icc_profile_error(png_ptr, NULL, name, temp,
"unexpected NamedColor ICC profile class");
break;
default:
/* To allow for future enhancements to the profile accept unrecognized
* profile classes with a warning, these then hit the test below on the
* tag content to ensure they are backward compatible with one of the
* understood profiles.
*/
(void)png_icc_profile_error(png_ptr, NULL, name, temp,
"unrecognized ICC profile class");
break;
}
/* For any profile other than a device link one the PCS must be encoded
* either in XYZ or Lab.
*/
temp = png_get_uint_32(profile+20);
switch (temp)
{
case 0x58595A20: /* 'XYZ ' */
case 0x4C616220: /* 'Lab ' */
break;
default:
return png_icc_profile_error(png_ptr, colorspace, name, temp,
"unexpected ICC PCS encoding");
}
return 1;
}
int /* PRIVATE */
png_icc_check_tag_table(png_const_structrp png_ptr, png_colorspacerp colorspace,
png_const_charp name, png_uint_32 profile_length,
png_const_bytep profile /* header plus whole tag table */)
{
png_uint_32 tag_count = png_get_uint_32(profile+128);
png_uint_32 itag;
png_const_bytep tag = profile+132; /* The first tag */
/* First scan all the tags in the table and add bits to the icc_info value
* (temporarily in 'tags').
*/
for (itag=0; itag < tag_count; ++itag, tag += 12)
{
png_uint_32 tag_id = png_get_uint_32(tag+0);
png_uint_32 tag_start = png_get_uint_32(tag+4); /* must be aligned */
png_uint_32 tag_length = png_get_uint_32(tag+8);/* not padded */
/* The ICC specification does not exclude zero length tags, therefore the
* start might actually be anywhere if there is no data, but this would be
* a clear abuse of the intent of the standard so the start is checked for
* being in range. All defined tag types have an 8 byte header - a 4 byte
* type signature then 0.
*/
if ((tag_start & 3) != 0)
{
/* CNHP730S.icc shipped with Microsoft Windows 64 violates this, it is
* only a warning here because libpng does not care about the
* alignment.
*/
(void)png_icc_profile_error(png_ptr, NULL, name, tag_id,
"ICC profile tag start not a multiple of 4");
}
/* This is a hard error; potentially it can cause read outside the
* profile.
*/
if (tag_start > profile_length || tag_length > profile_length - tag_start)
return png_icc_profile_error(png_ptr, colorspace, name, tag_id,
"ICC profile tag outside profile");
}
return 1; /* success, maybe with warnings */
}
#if defined(PNG_sRGB_SUPPORTED) && PNG_sRGB_PROFILE_CHECKS >= 0
/* Information about the known ICC sRGB profiles */
static const struct
{
png_uint_32 adler, crc, length;
png_uint_32 md5[4];
png_byte have_md5;
png_byte is_broken;
png_uint_16 intent;
# define PNG_MD5(a,b,c,d) { a, b, c, d }, (a!=0)||(b!=0)||(c!=0)||(d!=0)
# define PNG_ICC_CHECKSUM(adler, crc, md5, intent, broke, date, length, fname)\
{ adler, crc, length, md5, broke, intent },
} png_sRGB_checks[] =
{
/* This data comes from contrib/tools/checksum-icc run on downloads of
* all four ICC sRGB profiles from www.color.org.
*/
/* adler32, crc32, MD5[4], intent, date, length, file-name */
PNG_ICC_CHECKSUM(0x0a3fd9f6, 0x3b8772b9,
PNG_MD5(0x29f83dde, 0xaff255ae, 0x7842fae4, 0xca83390d), 0, 0,
"2009/03/27 21:36:31", 3048, "sRGB_IEC61966-2-1_black_scaled.icc")
/* ICC sRGB v2 perceptual no black-compensation: */
src/Source/LibPNG/png.c view on Meta::CPAN
PNG_ICC_CHECKSUM(0xf784f3fb, 0x182ea552,
PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 0, 1/*broken*/,
"1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 perceptual")
PNG_ICC_CHECKSUM(0x0398f3fc, 0xf29e526d,
PNG_MD5(0x00000000, 0x00000000, 0x00000000, 0x00000000), 1, 1/*broken*/,
"1998/02/09 06:49:00", 3144, "HP-Microsoft sRGB v2 media-relative")
};
static int
png_compare_ICC_profile_with_sRGB(png_const_structrp png_ptr,
png_const_bytep profile, uLong adler)
{
/* The quick check is to verify just the MD5 signature and trust the
* rest of the data. Because the profile has already been verified for
* correctness this is safe. png_colorspace_set_sRGB will check the 'intent'
* field too, so if the profile has been edited with an intent not defined
* by sRGB (but maybe defined by a later ICC specification) the read of
* the profile will fail at that point.
*/
png_uint_32 length = 0;
png_uint_32 intent = 0x10000; /* invalid */
#if PNG_sRGB_PROFILE_CHECKS > 1
uLong crc = 0; /* the value for 0 length data */
#endif
unsigned int i;
#ifdef PNG_SET_OPTION_SUPPORTED
/* First see if PNG_SKIP_sRGB_CHECK_PROFILE has been set to "on" */
if (((png_ptr->options >> PNG_SKIP_sRGB_CHECK_PROFILE) & 3) ==
PNG_OPTION_ON)
return 0;
#endif
for (i=0; i < (sizeof png_sRGB_checks) / (sizeof png_sRGB_checks[0]); ++i)
{
if (png_get_uint_32(profile+84) == png_sRGB_checks[i].md5[0] &&
png_get_uint_32(profile+88) == png_sRGB_checks[i].md5[1] &&
png_get_uint_32(profile+92) == png_sRGB_checks[i].md5[2] &&
png_get_uint_32(profile+96) == png_sRGB_checks[i].md5[3])
{
/* This may be one of the old HP profiles without an MD5, in that
* case we can only use the length and Adler32 (note that these
* are not used by default if there is an MD5!)
*/
# if PNG_sRGB_PROFILE_CHECKS == 0
if (png_sRGB_checks[i].have_md5 != 0)
return 1+png_sRGB_checks[i].is_broken;
# endif
/* Profile is unsigned or more checks have been configured in. */
if (length == 0)
{
length = png_get_uint_32(profile);
intent = png_get_uint_32(profile+64);
}
/* Length *and* intent must match */
if (length == png_sRGB_checks[i].length &&
intent == png_sRGB_checks[i].intent)
{
/* Now calculate the adler32 if not done already. */
if (adler == 0)
{
adler = adler32(0, NULL, 0);
adler = adler32(adler, profile, length);
}
if (adler == png_sRGB_checks[i].adler)
{
/* These basic checks suggest that the data has not been
* modified, but if the check level is more than 1 perform
* our own crc32 checksum on the data.
*/
# if PNG_sRGB_PROFILE_CHECKS > 1
if (crc == 0)
{
crc = crc32(0, NULL, 0);
crc = crc32(crc, profile, length);
}
/* So this check must pass for the 'return' below to happen.
*/
if (crc == png_sRGB_checks[i].crc)
# endif
{
if (png_sRGB_checks[i].is_broken != 0)
{
/* These profiles are known to have bad data that may cause
* problems if they are used, therefore attempt to
* discourage their use, skip the 'have_md5' warning below,
* which is made irrelevant by this error.
*/
png_chunk_report(png_ptr, "known incorrect sRGB profile",
PNG_CHUNK_ERROR);
}
/* Warn that this being done; this isn't even an error since
* the profile is perfectly valid, but it would be nice if
* people used the up-to-date ones.
*/
else if (png_sRGB_checks[i].have_md5 == 0)
{
png_chunk_report(png_ptr, "out-of-date sRGB profile with"
" no signature",
PNG_CHUNK_WARNING);
}
return 1+png_sRGB_checks[i].is_broken;
}
}
# if PNG_sRGB_PROFILE_CHECKS > 0
/* The signature matched, but the profile had been changed in some
* way. This probably indicates a data error or uninformed hacking.
* Fall through to "no match".
*/
png_chunk_report(png_ptr, "Not recognizing known sRGB profile that"
" has been edited",
PNG_CHUNK_WARNING);
break;
# endif
}
}
}
return 0; /* no match */
}
#endif
#ifdef PNG_sRGB_SUPPORTED
void /* PRIVATE */
png_icc_set_sRGB(png_const_structrp png_ptr,
png_colorspacerp colorspace, png_const_bytep profile, uLong adler)
{
/* Is this profile one of the known ICC sRGB profiles? If it is, just set
* the sRGB information.
*/
#if PNG_sRGB_PROFILE_CHECKS >= 0
if (png_compare_ICC_profile_with_sRGB(png_ptr, profile, adler) != 0)
#endif
(void)png_colorspace_set_sRGB(png_ptr, colorspace,
(int)/*already checked*/png_get_uint_32(profile+64));
}
#endif /* READ_sRGB */
int /* PRIVATE */
png_colorspace_set_ICC(png_const_structrp png_ptr, png_colorspacerp colorspace,
png_const_charp name, png_uint_32 profile_length, png_const_bytep profile,
int color_type)
{
if ((colorspace->flags & PNG_COLORSPACE_INVALID) != 0)
return 0;
if (png_icc_check_length(png_ptr, colorspace, name, profile_length) != 0 &&
png_icc_check_header(png_ptr, colorspace, name, profile_length, profile,
color_type) != 0 &&
png_icc_check_tag_table(png_ptr, colorspace, name, profile_length,
profile) != 0)
{
# ifdef PNG_sRGB_SUPPORTED
/* If no sRGB support, don't try storing sRGB information */
png_icc_set_sRGB(png_ptr, colorspace, profile, 0);
# endif
return 1;
}
/* Failure case */
return 0;
}
#endif /* iCCP */
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
void /* PRIVATE */
png_colorspace_set_rgb_coefficients(png_structrp png_ptr)
{
/* Set the rgb_to_gray coefficients from the colorspace. */
if (png_ptr->rgb_to_gray_coefficients_set == 0 &&
(png_ptr->colorspace.flags & PNG_COLORSPACE_HAVE_ENDPOINTS) != 0)
{
/* png_set_background has not been called, get the coefficients from the Y
* values of the colorspace colorants.
*/
png_fixed_point r = png_ptr->colorspace.end_points_XYZ.red_Y;
png_fixed_point g = png_ptr->colorspace.end_points_XYZ.green_Y;
png_fixed_point b = png_ptr->colorspace.end_points_XYZ.blue_Y;
png_fixed_point total = r+g+b;
if (total > 0 &&
r >= 0 && png_muldiv(&r, r, 32768, total) && r >= 0 && r <= 32768 &&
g >= 0 && png_muldiv(&g, g, 32768, total) && g >= 0 && g <= 32768 &&
b >= 0 && png_muldiv(&b, b, 32768, total) && b >= 0 && b <= 32768 &&
r+g+b <= 32769)
{
/* We allow 0 coefficients here. r+g+b may be 32769 if two or
* all of the coefficients were rounded up. Handle this by
* reducing the *largest* coefficient by 1; this matches the
* approach used for the default coefficients in pngrtran.c
*/
int add = 0;
if (r+g+b > 32768)
add = -1;
else if (r+g+b < 32768)
add = 1;
if (add != 0)
{
if (g >= r && g >= b)
g += add;
else if (r >= g && r >= b)
r += add;
else
b += add;
}
/* Check for an internal error. */
if (r+g+b != 32768)
png_error(png_ptr,
"internal error handling cHRM coefficients");
else
{
png_ptr->rgb_to_gray_red_coeff = (png_uint_16)r;
png_ptr->rgb_to_gray_green_coeff = (png_uint_16)g;
}
}
/* This is a png_error at present even though it could be ignored -
* it should never happen, but it is important that if it does, the
* bug is fixed.
*/
else
png_error(png_ptr, "internal error handling cHRM->XYZ");
}
}
#endif
#endif /* COLORSPACE */
#ifdef __GNUC__
/* This exists solely to work round a warning from GNU C. */
static int /* PRIVATE */
png_gt(size_t a, size_t b)
{
return a > b;
}
#else
# define png_gt(a,b) ((a) > (b))
#endif
void /* PRIVATE */
png_check_IHDR(png_const_structrp png_ptr,
png_uint_32 width, png_uint_32 height, int bit_depth,
int color_type, int interlace_type, int compression_type,
int filter_type)
{
int error = 0;
/* Check for width and height valid values */
if (width == 0)
{
png_warning(png_ptr, "Image width is zero in IHDR");
error = 1;
}
else if (width > PNG_UINT_31_MAX)
{
png_warning(png_ptr, "Invalid image width in IHDR");
error = 1;
}
else if (png_gt(width,
(PNG_SIZE_MAX >> 3) /* 8-byte RGBA pixels */
- 48 /* big_row_buf hack */
- 1 /* filter byte */
- 7*8 /* rounding width to multiple of 8 pix */
- 8)) /* extra max_pixel_depth pad */
{
/* The size of the row must be within the limits of this architecture.
* Because the read code can perform arbitrary transformations the
* maximum size is checked here. Because the code in png_read_start_row
* adds extra space "for safety's sake" in several places a conservative
* limit is used here.
*
* NOTE: it would be far better to check the size that is actually used,
* but the effect in the real world is minor and the changes are more
* extensive, therefore much more dangerous and much more difficult to
* write in a way that avoids compiler warnings.
*/
png_warning(png_ptr, "Image width is too large for this architecture");
error = 1;
}
else
{
# ifdef PNG_SET_USER_LIMITS_SUPPORTED
if (width > png_ptr->user_width_max)
# else
if (width > PNG_USER_WIDTH_MAX)
# endif
{
png_warning(png_ptr, "Image width exceeds user limit in IHDR");
error = 1;
}
}
if (height == 0)
{
png_warning(png_ptr, "Image height is zero in IHDR");
error = 1;
}
else if (height > PNG_UINT_31_MAX)
{
png_warning(png_ptr, "Invalid image height in IHDR");
error = 1;
}
else
{
# ifdef PNG_SET_USER_LIMITS_SUPPORTED
if (height > png_ptr->user_height_max)
# else
if (height > PNG_USER_HEIGHT_MAX)
# endif
{
png_warning(png_ptr, "Image height exceeds user limit in IHDR");
error = 1;
}
}
/* Check other values */
if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 &&
bit_depth != 8 && bit_depth != 16)
{
png_warning(png_ptr, "Invalid bit depth in IHDR");
error = 1;
}
if (color_type < 0 || color_type == 1 ||
color_type == 5 || color_type > 6)
{
png_warning(png_ptr, "Invalid color type in IHDR");
error = 1;
}
if (((color_type == PNG_COLOR_TYPE_PALETTE) && bit_depth > 8) ||
((color_type == PNG_COLOR_TYPE_RGB ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA ||
color_type == PNG_COLOR_TYPE_RGB_ALPHA) && bit_depth < 8))
{
png_warning(png_ptr, "Invalid color type/bit depth combination in IHDR");
error = 1;
}
if (interlace_type >= PNG_INTERLACE_LAST)
{
png_warning(png_ptr, "Unknown interlace method in IHDR");
error = 1;
}
if (compression_type != PNG_COMPRESSION_TYPE_BASE)
{
png_warning(png_ptr, "Unknown compression method in IHDR");
error = 1;
}
# ifdef PNG_MNG_FEATURES_SUPPORTED
/* Accept filter_method 64 (intrapixel differencing) only if
* 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
* 2. Libpng did not read a PNG signature (this filter_method is only
* used in PNG datastreams that are embedded in MNG datastreams) and
* 3. The application called png_permit_mng_features with a mask that
* included PNG_FLAG_MNG_FILTER_64 and
* 4. The filter_method is 64 and
* 5. The color_type is RGB or RGBA
*/
if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0 &&
png_ptr->mng_features_permitted != 0)
png_warning(png_ptr, "MNG features are not allowed in a PNG datastream");
if (filter_type != PNG_FILTER_TYPE_BASE)
{
if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) != 0 &&
(filter_type == PNG_INTRAPIXEL_DIFFERENCING) &&
((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) &&
(color_type == PNG_COLOR_TYPE_RGB ||
color_type == PNG_COLOR_TYPE_RGB_ALPHA)))
{
png_warning(png_ptr, "Unknown filter method in IHDR");
error = 1;
}
if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) != 0)
{
png_warning(png_ptr, "Invalid filter method in IHDR");
error = 1;
}
}
# else
if (filter_type != PNG_FILTER_TYPE_BASE)
{
png_warning(png_ptr, "Unknown filter method in IHDR");
error = 1;
}
# endif
if (error == 1)
png_error(png_ptr, "Invalid IHDR data");
}
#if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED)
/* ASCII to fp functions */
/* Check an ASCII formated floating point value, see the more detailed
* comments in pngpriv.h
*/
/* The following is used internally to preserve the sticky flags */
#define png_fp_add(state, flags) ((state) |= (flags))
#define png_fp_set(state, value) ((state) = (value) | ((state) & PNG_FP_STICKY))
int /* PRIVATE */
png_check_fp_number(png_const_charp string, png_size_t size, int *statep,
png_size_tp whereami)
{
int state = *statep;
png_size_t i = *whereami;
while (i < size)
{
int type;
/* First find the type of the next character */
switch (string[i])
{
case 43: type = PNG_FP_SAW_SIGN; break;
case 45: type = PNG_FP_SAW_SIGN + PNG_FP_NEGATIVE; break;
case 46: type = PNG_FP_SAW_DOT; break;
src/Source/LibPNG/png.c view on Meta::CPAN
/* Now deal with this type according to the current
* state, the type is arranged to not overlap the
* bits of the PNG_FP_STATE.
*/
switch ((state & PNG_FP_STATE) + (type & PNG_FP_SAW_ANY))
{
case PNG_FP_INTEGER + PNG_FP_SAW_SIGN:
if ((state & PNG_FP_SAW_ANY) != 0)
goto PNG_FP_End; /* not a part of the number */
png_fp_add(state, type);
break;
case PNG_FP_INTEGER + PNG_FP_SAW_DOT:
/* Ok as trailer, ok as lead of fraction. */
if ((state & PNG_FP_SAW_DOT) != 0) /* two dots */
goto PNG_FP_End;
else if ((state & PNG_FP_SAW_DIGIT) != 0) /* trailing dot? */
png_fp_add(state, type);
else
png_fp_set(state, PNG_FP_FRACTION | type);
break;
case PNG_FP_INTEGER + PNG_FP_SAW_DIGIT:
if ((state & PNG_FP_SAW_DOT) != 0) /* delayed fraction */
png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT);
png_fp_add(state, type | PNG_FP_WAS_VALID);
break;
case PNG_FP_INTEGER + PNG_FP_SAW_E:
if ((state & PNG_FP_SAW_DIGIT) == 0)
goto PNG_FP_End;
png_fp_set(state, PNG_FP_EXPONENT);
break;
/* case PNG_FP_FRACTION + PNG_FP_SAW_SIGN:
goto PNG_FP_End; ** no sign in fraction */
/* case PNG_FP_FRACTION + PNG_FP_SAW_DOT:
goto PNG_FP_End; ** Because SAW_DOT is always set */
case PNG_FP_FRACTION + PNG_FP_SAW_DIGIT:
png_fp_add(state, type | PNG_FP_WAS_VALID);
break;
case PNG_FP_FRACTION + PNG_FP_SAW_E:
/* This is correct because the trailing '.' on an
* integer is handled above - so we can only get here
* with the sequence ".E" (with no preceding digits).
*/
if ((state & PNG_FP_SAW_DIGIT) == 0)
goto PNG_FP_End;
png_fp_set(state, PNG_FP_EXPONENT);
break;
case PNG_FP_EXPONENT + PNG_FP_SAW_SIGN:
if ((state & PNG_FP_SAW_ANY) != 0)
goto PNG_FP_End; /* not a part of the number */
png_fp_add(state, PNG_FP_SAW_SIGN);
break;
/* case PNG_FP_EXPONENT + PNG_FP_SAW_DOT:
goto PNG_FP_End; */
case PNG_FP_EXPONENT + PNG_FP_SAW_DIGIT:
png_fp_add(state, PNG_FP_SAW_DIGIT | PNG_FP_WAS_VALID);
break;
/* case PNG_FP_EXPONEXT + PNG_FP_SAW_E:
goto PNG_FP_End; */
default: goto PNG_FP_End; /* I.e. break 2 */
}
/* The character seems ok, continue. */
src/Source/LibPNG/png.c view on Meta::CPAN
*/
*statep = state;
*whereami = i;
return (state & PNG_FP_SAW_DIGIT) != 0;
}
/* The same but for a complete string. */
int
png_check_fp_string(png_const_charp string, png_size_t size)
{
int state=0;
png_size_t char_index=0;
if (png_check_fp_number(string, size, &state, &char_index) != 0 &&
(char_index == size || string[char_index] == 0))
return state /* must be non-zero - see above */;
return 0; /* i.e. fail */
}
#endif /* pCAL || sCAL */
#ifdef PNG_sCAL_SUPPORTED
# ifdef PNG_FLOATING_POINT_SUPPORTED
/* Utility used below - a simple accurate power of ten from an integral
* exponent.
*/
static double
png_pow10(int power)
{
int recip = 0;
double d = 1;
/* Handle negative exponent with a reciprocal at the end because
* 10 is exact whereas .1 is inexact in base 2
*/
if (power < 0)
{
if (power < DBL_MIN_10_EXP) return 0;
src/Source/LibPNG/png.c view on Meta::CPAN
}
/* else power is 0 and d is 1 */
return d;
}
/* Function to format a floating point value in ASCII with a given
* precision.
*/
void /* PRIVATE */
png_ascii_from_fp(png_const_structrp png_ptr, png_charp ascii, png_size_t size,
double fp, unsigned int precision)
{
/* We use standard functions from math.h, but not printf because
* that would require stdio. The caller must supply a buffer of
* sufficient size or we will png_error. The tests on size and
* the space in ascii[] consumed are indicated below.
*/
if (precision < 1)
precision = DBL_DIG;
/* Enforce the limit of the implementation precision too. */
if (precision > DBL_DIG+1)
precision = DBL_DIG+1;
/* Basic sanity checks */
src/Source/LibPNG/png.c view on Meta::CPAN
* be increased. Note that the arithmetic shift
* performs a floor() unlike C arithmetic - using a
* C multiply would break the following for negative
* exponents.
*/
(void)frexp(fp, &exp_b10); /* exponent to base 2 */
exp_b10 = (exp_b10 * 77) >> 8; /* <= exponent to base 10 */
/* Avoid underflow here. */
base = png_pow10(exp_b10); /* May underflow */
while (base < DBL_MIN || base < fp)
{
/* And this may overflow. */
double test = png_pow10(exp_b10+1);
if (test <= DBL_MAX)
++exp_b10, base = test;
else
break;
}
/* Normalize fp and correct exp_b10, after this fp is in the
* range [.1,1) and exp_b10 is both the exponent and the digit
src/Source/LibPNG/png.c view on Meta::CPAN
{
*ascii++ = 105; /* 'i' */
*ascii++ = 110; /* 'n' */
*ascii++ = 102; /* 'f' */
*ascii = 0;
return;
}
}
/* Here on buffer too small. */
png_error(png_ptr, "ASCII conversion buffer too small");
}
# endif /* FLOATING_POINT */
# ifdef PNG_FIXED_POINT_SUPPORTED
/* Function to format a fixed point value in ASCII.
*/
void /* PRIVATE */
png_ascii_from_fixed(png_const_structrp png_ptr, png_charp ascii,
png_size_t size, png_fixed_point fp)
{
/* Require space for 10 decimal digits, a decimal point, a minus sign and a
* trailing \0, 13 characters:
*/
if (size > 12)
{
png_uint_32 num;
/* Avoid overflow here on the minimum integer. */
if (fp < 0)
*ascii++ = 45, --size, num = -fp;
else
num = fp;
if (num <= 0x80000000) /* else overflowed */
{
unsigned int ndigits = 0, first = 16 /* flag value */;
src/Source/LibPNG/png.c view on Meta::CPAN
else
*ascii++ = 48;
/* And null terminate the string: */
*ascii = 0;
return;
}
}
/* Here on buffer too small. */
png_error(png_ptr, "ASCII conversion buffer too small");
}
# endif /* FIXED_POINT */
#endif /* READ_SCAL */
#if defined(PNG_FLOATING_POINT_SUPPORTED) && \
!defined(PNG_FIXED_POINT_MACRO_SUPPORTED) && \
(defined(PNG_gAMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED) || \
defined(PNG_sCAL_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) || \
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)) || \
(defined(PNG_sCAL_SUPPORTED) && \
defined(PNG_FLOATING_ARITHMETIC_SUPPORTED))
png_fixed_point
png_fixed(png_const_structrp png_ptr, double fp, png_const_charp text)
{
double r = floor(100000 * fp + .5);
if (r > 2147483647. || r < -2147483648.)
png_fixed_error(png_ptr, text);
# ifndef PNG_ERROR_TEXT_SUPPORTED
PNG_UNUSED(text)
# endif
return (png_fixed_point)r;
}
#endif
#if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_COLORSPACE_SUPPORTED) ||\
defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG_READ_pHYs_SUPPORTED)
/* muldiv functions */
/* This API takes signed arguments and rounds the result to the nearest
* integer (or, for a fixed point number - the standard argument - to
* the nearest .00001). Overflow and divide by zero are signalled in
* the result, a boolean - true on success, false on overflow.
*/
int
png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times,
png_int_32 divisor)
{
/* Return a * times / divisor, rounded. */
if (divisor != 0)
{
if (a == 0 || times == 0)
{
*res = 0;
return 1;
}
else
{
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
double r = a;
r *= times;
r /= divisor;
r = floor(r+.5);
/* A png_fixed_point is a 32-bit integer. */
if (r <= 2147483647. && r >= -2147483648.)
{
*res = (png_fixed_point)r;
return 1;
}
#else
int negative = 0;
png_uint_32 A, T, D;
png_uint_32 s16, s32, s00;
if (a < 0)
negative = 1, A = -a;
else
A = a;
if (times < 0)
negative = !negative, T = -times;
else
T = times;
src/Source/LibPNG/png.c view on Meta::CPAN
if (s00 < s16)
++s32; /* carry */
if (s32 < D) /* else overflow */
{
/* s32.s00 is now the 64-bit product, do a standard
* division, we know that s32 < D, so the maximum
* required shift is 31.
*/
int bitshift = 32;
png_fixed_point result = 0; /* NOTE: signed */
while (--bitshift >= 0)
{
png_uint_32 d32, d00;
if (bitshift > 0)
d32 = D >> (32-bitshift), d00 = D << bitshift;
else
d32 = 0, d00 = D;
if (s32 > d32)
{
if (s00 < d00) --s32; /* carry */
src/Source/LibPNG/png.c view on Meta::CPAN
}
return 0;
}
#endif /* READ_GAMMA || INCH_CONVERSIONS */
#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED)
/* The following is for when the caller doesn't much care about the
* result.
*/
png_fixed_point
png_muldiv_warn(png_const_structrp png_ptr, png_fixed_point a, png_int_32 times,
png_int_32 divisor)
{
png_fixed_point result;
if (png_muldiv(&result, a, times, divisor) != 0)
return result;
png_warning(png_ptr, "fixed point overflow ignored");
return 0;
}
#endif
#ifdef PNG_GAMMA_SUPPORTED /* more fixed point functions for gamma */
/* Calculate a reciprocal, return 0 on div-by-zero or overflow. */
png_fixed_point
png_reciprocal(png_fixed_point a)
{
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
double r = floor(1E10/a+.5);
if (r <= 2147483647. && r >= -2147483648.)
return (png_fixed_point)r;
#else
png_fixed_point res;
if (png_muldiv(&res, 100000, 100000, a) != 0)
return res;
#endif
return 0; /* error/overflow */
}
/* This is the shared test on whether a gamma value is 'significant' - whether
* it is worth doing gamma correction.
*/
int /* PRIVATE */
png_gamma_significant(png_fixed_point gamma_val)
{
return gamma_val < PNG_FP_1 - PNG_GAMMA_THRESHOLD_FIXED ||
gamma_val > PNG_FP_1 + PNG_GAMMA_THRESHOLD_FIXED;
}
#endif
#ifdef PNG_READ_GAMMA_SUPPORTED
#if defined(PNG_16BIT_SUPPORTED) || !defined(PNG_FLOATING_ARITHMETIC_SUPPORTED)
/* A local convenience routine. */
static png_fixed_point
png_product2(png_fixed_point a, png_fixed_point b)
{
/* The required result is 1/a * 1/b; the following preserves accuracy. */
# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
double r = a * 1E-5;
r *= b;
r = floor(r+.5);
if (r <= 2147483647. && r >= -2147483648.)
return (png_fixed_point)r;
# else
png_fixed_point res;
if (png_muldiv(&res, a, b, 100000) != 0)
return res;
# endif
return 0; /* overflow */
}
#endif /* 16BIT || !FLOATING_ARITHMETIC */
/* The inverse of the above. */
png_fixed_point
png_reciprocal2(png_fixed_point a, png_fixed_point b)
{
/* The required result is 1/a * 1/b; the following preserves accuracy. */
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
double r = 1E15/a;
r /= b;
r = floor(r+.5);
if (r <= 2147483647. && r >= -2147483648.)
return (png_fixed_point)r;
#else
/* This may overflow because the range of png_fixed_point isn't symmetric,
* but this API is only used for the product of file and screen gamma so it
* doesn't matter that the smallest number it can produce is 1/21474, not
* 1/100000
*/
png_fixed_point res = png_product2(a, b);
if (res != 0)
return png_reciprocal(res);
#endif
return 0; /* overflow */
}
#endif /* READ_GAMMA */
#ifdef PNG_READ_GAMMA_SUPPORTED /* gamma table code */
#ifndef PNG_FLOATING_ARITHMETIC_SUPPORTED
/* Fixed point gamma.
*
src/Source/LibPNG/png.c view on Meta::CPAN
* or 16-bit sample values.
*
* The tables used here were calculated using simple 'bc' programs, but C double
* precision floating point arithmetic would work fine.
*
* 8-bit log table
* This is a table of -log(value/255)/log(2) for 'value' in the range 128 to
* 255, so it's the base 2 logarithm of a normalized 8-bit floating point
* mantissa. The numbers are 32-bit fractions.
*/
static const png_uint_32
png_8bit_l2[128] =
{
4270715492U, 4222494797U, 4174646467U, 4127164793U, 4080044201U, 4033279239U,
3986864580U, 3940795015U, 3895065449U, 3849670902U, 3804606499U, 3759867474U,
3715449162U, 3671346997U, 3627556511U, 3584073329U, 3540893168U, 3498011834U,
3455425220U, 3413129301U, 3371120137U, 3329393864U, 3287946700U, 3246774933U,
3205874930U, 3165243125U, 3124876025U, 3084770202U, 3044922296U, 3005329011U,
2965987113U, 2926893432U, 2888044853U, 2849438323U, 2811070844U, 2772939474U,
2735041326U, 2697373562U, 2659933400U, 2622718104U, 2585724991U, 2548951424U,
2512394810U, 2476052606U, 2439922311U, 2404001468U, 2368287663U, 2332778523U,
2297471715U, 2262364947U, 2227455964U, 2192742551U, 2158222529U, 2123893754U,
src/Source/LibPNG/png.c view on Meta::CPAN
31369, 30854, 30341, 29832, 29325, 28820, 28319, 27820, 27324, 26830, 26339,
25850, 25364, 24880, 24399, 23920, 23444, 22970, 22499, 22029, 21562, 21098,
20636, 20175, 19718, 19262, 18808, 18357, 17908, 17461, 17016, 16573, 16132,
15694, 15257, 14822, 14390, 13959, 13530, 13103, 12678, 12255, 11834, 11415,
10997, 10582, 10168, 9756, 9346, 8937, 8531, 8126, 7723, 7321, 6921, 6523,
6127, 5732, 5339, 4947, 4557, 4169, 3782, 3397, 3014, 2632, 2251, 1872, 1495,
1119, 744, 372
#endif
};
static png_int_32
png_log8bit(unsigned int x)
{
unsigned int lg2 = 0;
/* Each time 'x' is multiplied by 2, 1 must be subtracted off the final log,
* because the log is actually negate that means adding 1. The final
* returned value thus has the range 0 (for 255 input) to 7.994 (for 1
* input), return -1 for the overflow (log 0) case, - so the result is
* always at most 19 bits.
*/
if ((x &= 0xff) == 0)
return -1;
src/Source/LibPNG/png.c view on Meta::CPAN
if ((x & 0xf0) == 0)
lg2 = 4, x <<= 4;
if ((x & 0xc0) == 0)
lg2 += 2, x <<= 2;
if ((x & 0x80) == 0)
lg2 += 1, x <<= 1;
/* result is at most 19 bits, so this cast is safe: */
return (png_int_32)((lg2 << 16) + ((png_8bit_l2[x-128]+32768)>>16));
}
/* The above gives exact (to 16 binary places) log2 values for 8-bit images,
* for 16-bit images we use the most significant 8 bits of the 16-bit value to
* get an approximation then multiply the approximation by a correction factor
* determined by the remaining up to 8 bits. This requires an additional step
* in the 16-bit case.
*
* We want log2(value/65535), we have log2(v'/255), where:
*
src/Source/LibPNG/png.c view on Meta::CPAN
* Since these numbers are so close to '1' we can use simple linear
* interpolation between the two end values 256/257 (result -368.61) and 258/257
* (result 367.179). The values used below are scaled by a further 64 to give
* 16-bit precision in the interpolation:
*
* Start (256): -23591
* Zero (257): 0
* End (258): 23499
*/
#ifdef PNG_16BIT_SUPPORTED
static png_int_32
png_log16bit(png_uint_32 x)
{
unsigned int lg2 = 0;
/* As above, but now the input has 16 bits. */
if ((x &= 0xffff) == 0)
return -1;
if ((x & 0xff00) == 0)
lg2 = 8, x <<= 8;
src/Source/LibPNG/png.c view on Meta::CPAN
if ((x & 0xc000) == 0)
lg2 += 2, x <<= 2;
if ((x & 0x8000) == 0)
lg2 += 1, x <<= 1;
/* Calculate the base logarithm from the top 8 bits as a 28-bit fractional
* value.
*/
lg2 <<= 28;
lg2 += (png_8bit_l2[(x>>8)-128]+8) >> 4;
/* Now we need to interpolate the factor, this requires a division by the top
* 8 bits. Do this with maximum precision.
*/
x = ((x << 16) + (x >> 9)) / (x >> 8);
/* Since we divided by the top 8 bits of 'x' there will be a '1' at 1<<24,
* the value at 1<<16 (ignoring this) will be 0 or 1; this gives us exactly
* 16 bits to interpolate to get the low bits of the result. Round the
* answer. Note that the end point values are scaled by 64 to retain overall
src/Source/LibPNG/png.c view on Meta::CPAN
*/
x -= 1U << 24;
if (x <= 65536U) /* <= '257' */
lg2 += ((23591U * (65536U-x)) + (1U << (16+6-12-1))) >> (16+6-12);
else
lg2 -= ((23499U * (x-65536U)) + (1U << (16+6-12-1))) >> (16+6-12);
/* Safe, because the result can't have more than 20 bits: */
return (png_int_32)((lg2 + 2048) >> 12);
}
#endif /* 16BIT */
/* The 'exp()' case must invert the above, taking a 20-bit fixed point
* logarithmic value and returning a 16 or 8-bit number as appropriate. In
* each case only the low 16 bits are relevant - the fraction - since the
* integer bits (the top 4) simply determine a shift.
*
* The worst case is the 16-bit distinction between 65535 and 65534. This
* requires perhaps spurious accuracy in the decoding of the logarithm to
* distinguish log2(65535/65534.5) - 10^-5 or 17 bits. There is little chance
* of getting this accuracy in practice.
*
* To deal with this the following exp() function works out the exponent of the
* frational part of the logarithm by using an accurate 32-bit value from the
* top four fractional bits then multiplying in the remaining bits.
*/
static const png_uint_32
png_32bit_exp[16] =
{
/* NOTE: the first entry is deliberately set to the maximum 32-bit value. */
4294967295U, 4112874773U, 3938502376U, 3771522796U, 3611622603U, 3458501653U,
3311872529U, 3171459999U, 3037000500U, 2908241642U, 2784941738U, 2666869345U,
2553802834U, 2445529972U, 2341847524U, 2242560872U
};
/* Adjustment table; provided to explain the numbers in the code below. */
#if 0
for (i=11;i>=0;--i){ print i, " ", (1 - e(-(2^i)/65536*l(2))) * 2^(32-i), "\n"}
src/Source/LibPNG/png.c view on Meta::CPAN
7 45395.35850361789624614912
6 45410.72259715102037508096
5 45418.40724413220722311168
4 45422.25021786898173001728
3 45424.17186732298419044352
2 45425.13273269940811464704
1 45425.61317555035558641664
0 45425.85339951654943850496
#endif
static png_uint_32
png_exp(png_fixed_point x)
{
if (x > 0 && x <= 0xfffff) /* Else overflow or zero (underflow) */
{
/* Obtain a 4-bit approximation */
png_uint_32 e = png_32bit_exp[(x >> 12) & 0xf];
/* Incorporate the low 12 bits - these decrease the returned value by
* multiplying by a number less than 1 if the bit is set. The multiplier
* is determined by the above table and the shift. Notice that the values
* converge on 45426 and this is used to allow linear interpolation of the
* low bits.
*/
if (x & 0x800)
e -= (((e >> 16) * 44938U) + 16U) >> 5;
src/Source/LibPNG/png.c view on Meta::CPAN
/* And handle the low 6 bits in a single block. */
e -= (((e >> 16) * 355U * (x & 0x3fU)) + 256U) >> 9;
/* Handle the upper bits of x. */
e >>= x >> 16;
return e;
}
/* Check for overflow */
if (x <= 0)
return png_32bit_exp[0];
/* Else underflow */
return 0;
}
static png_byte
png_exp8bit(png_fixed_point lg2)
{
/* Get a 32-bit value: */
png_uint_32 x = png_exp(lg2);
/* Convert the 32-bit value to 0..255 by multiplying by 256-1. Note that the
* second, rounding, step can't overflow because of the first, subtraction,
* step.
*/
x -= x >> 8;
return (png_byte)((x + 0x7fffffU) >> 24);
}
#ifdef PNG_16BIT_SUPPORTED
static png_uint_16
png_exp16bit(png_fixed_point lg2)
{
/* Get a 32-bit value: */
png_uint_32 x = png_exp(lg2);
/* Convert the 32-bit value to 0..65535 by multiplying by 65536-1: */
x -= x >> 16;
return (png_uint_16)((x + 32767U) >> 16);
}
#endif /* 16BIT */
#endif /* FLOATING_ARITHMETIC */
png_byte
png_gamma_8bit_correct(unsigned int value, png_fixed_point gamma_val)
{
if (value > 0 && value < 255)
{
# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
/* 'value' is unsigned, ANSI-C90 requires the compiler to correctly
* convert this to a floating point value. This includes values that
* would overflow if 'value' were to be converted to 'int'.
*
* Apparently GCC, however, does an intermediate conversion to (int)
* on some (ARM) but not all (x86) platforms, possibly because of
src/Source/LibPNG/png.c view on Meta::CPAN
* won't be faster than an int to float one. Therefore this code
* assumes responsibility for the undefined behavior, which it knows
* can't happen because of the check above.
*
* Note the argument to this routine is an (unsigned int) because, on
* 16-bit platforms, it is assigned a value which might be out of
* range for an (int); that would result in undefined behavior in the
* caller if the *argument* ('value') were to be declared (int).
*/
double r = floor(255*pow((int)/*SAFE*/value/255.,gamma_val*.00001)+.5);
return (png_byte)r;
# else
png_int_32 lg2 = png_log8bit(value);
png_fixed_point res;
if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0)
return png_exp8bit(res);
/* Overflow. */
value = 0;
# endif
}
return (png_byte)value;
}
#ifdef PNG_16BIT_SUPPORTED
png_uint_16
png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val)
{
if (value > 0 && value < 65535)
{
# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
/* The same (unsigned int)->(double) constraints apply here as above,
* however in this case the (unsigned int) to (int) conversion can
* overflow on an ANSI-C90 compliant system so the cast needs to ensure
* that this is not possible.
*/
double r = floor(65535*pow((png_int_32)value/65535.,
gamma_val*.00001)+.5);
return (png_uint_16)r;
# else
png_int_32 lg2 = png_log16bit(value);
png_fixed_point res;
if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1) != 0)
return png_exp16bit(res);
/* Overflow. */
value = 0;
# endif
}
return (png_uint_16)value;
}
#endif /* 16BIT */
/* This does the right thing based on the bit_depth field of the
* png_struct, interpreting values as 8-bit or 16-bit. While the result
* is nominally a 16-bit value if bit depth is 8 then the result is
* 8-bit (as are the arguments.)
*/
png_uint_16 /* PRIVATE */
png_gamma_correct(png_structrp png_ptr, unsigned int value,
png_fixed_point gamma_val)
{
if (png_ptr->bit_depth == 8)
return png_gamma_8bit_correct(value, gamma_val);
#ifdef PNG_16BIT_SUPPORTED
else
return png_gamma_16bit_correct(value, gamma_val);
#else
/* should not reach this */
return 0;
#endif /* 16BIT */
}
#ifdef PNG_16BIT_SUPPORTED
/* Internal function to build a single 16-bit table - the table consists of
* 'num' 256 entry subtables, where 'num' is determined by 'shift' - the amount
* to shift the input values right (or 16-number_of_signifiant_bits).
*
* The caller is responsible for ensuring that the table gets cleaned up on
* png_error (i.e. if one of the mallocs below fails) - i.e. the *table argument
* should be somewhere that will be cleaned.
*/
static void
png_build_16bit_table(png_structrp png_ptr, png_uint_16pp *ptable,
PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
{
/* Various values derived from 'shift': */
PNG_CONST unsigned int num = 1U << (8U - shift);
#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
/* CSE the division and work round wacky GCC warnings (see the comments
* in png_gamma_8bit_correct for where these come from.)
*/
PNG_CONST double fmax = 1./(((png_int_32)1 << (16U - shift))-1);
#endif
PNG_CONST unsigned int max = (1U << (16U - shift))-1U;
PNG_CONST unsigned int max_by_2 = 1U << (15U-shift);
unsigned int i;
png_uint_16pp table = *ptable =
(png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p)));
for (i = 0; i < num; i++)
{
png_uint_16p sub_table = table[i] =
(png_uint_16p)png_malloc(png_ptr, 256 * (sizeof (png_uint_16)));
/* The 'threshold' test is repeated here because it can arise for one of
* the 16-bit tables even if the others don't hit it.
*/
if (png_gamma_significant(gamma_val) != 0)
{
/* The old code would overflow at the end and this would cause the
* 'pow' function to return a result >1, resulting in an
* arithmetic error. This code follows the spec exactly; ig is
* the recovered input sample, it always has 8-16 bits.
*
* We want input * 65535/max, rounded, the arithmetic fits in 32
* bits (unsigned) so long as max <= 32767.
*/
unsigned int j;
for (j = 0; j < 256; j++)
{
png_uint_32 ig = (j << (8-shift)) + i;
# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED
/* Inline the 'max' scaling operation: */
/* See png_gamma_8bit_correct for why the cast to (int) is
* required here.
*/
double d = floor(65535.*pow(ig*fmax, gamma_val*.00001)+.5);
sub_table[j] = (png_uint_16)d;
# else
if (shift != 0)
ig = (ig * 65535U + max_by_2)/max;
sub_table[j] = png_gamma_16bit_correct(ig, gamma_val);
# endif
}
}
else
{
/* We must still build a table, but do it the fast way. */
unsigned int j;
for (j = 0; j < 256; j++)
{
png_uint_32 ig = (j << (8-shift)) + i;
if (shift != 0)
ig = (ig * 65535U + max_by_2)/max;
sub_table[j] = (png_uint_16)ig;
}
}
}
}
/* NOTE: this function expects the *inverse* of the overall gamma transformation
* required.
*/
static void
png_build_16to8_table(png_structrp png_ptr, png_uint_16pp *ptable,
PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val)
{
PNG_CONST unsigned int num = 1U << (8U - shift);
PNG_CONST unsigned int max = (1U << (16U - shift))-1U;
unsigned int i;
png_uint_32 last;
png_uint_16pp table = *ptable =
(png_uint_16pp)png_calloc(png_ptr, num * (sizeof (png_uint_16p)));
/* 'num' is the number of tables and also the number of low bits of low
* bits of the input 16-bit value used to select a table. Each table is
* itself indexed by the high 8 bits of the value.
*/
for (i = 0; i < num; i++)
table[i] = (png_uint_16p)png_malloc(png_ptr,
256 * (sizeof (png_uint_16)));
/* 'gamma_val' is set to the reciprocal of the value calculated above, so
* pow(out,g) is an *input* value. 'last' is the last input value set.
*
* In the loop 'i' is used to find output values. Since the output is
* 8-bit there are only 256 possible values. The tables are set up to
* select the closest possible output value for each input by finding
* the input value at the boundary between each pair of output values
* and filling the table up to that boundary with the lower output
* value.
src/Source/LibPNG/png.c view on Meta::CPAN
* The boundary values are 0.5,1.5..253.5,254.5. Since these are 9-bit
* values the code below uses a 16-bit value in i; the values start at
* 128.5 (for 0.5) and step by 257, for a total of 254 values (the last
* entries are filled with 255). Start i at 128 and fill all 'last'
* table entries <= 'max'
*/
last = 0;
for (i = 0; i < 255; ++i) /* 8-bit output value */
{
/* Find the corresponding maximum input value */
png_uint_16 out = (png_uint_16)(i * 257U); /* 16-bit output value */
/* Find the boundary value in 16 bits: */
png_uint_32 bound = png_gamma_16bit_correct(out+128U, gamma_val);
/* Adjust (round) to (16-shift) bits: */
bound = (bound * max + 32768U)/65535U + 1U;
while (last < bound)
{
table[last & (0xffU >> shift)][last >> (8U - shift)] = out;
last++;
}
}
src/Source/LibPNG/png.c view on Meta::CPAN
/* And fill in the final entries. */
while (last < (num << 8))
{
table[last & (0xff >> shift)][last >> (8U - shift)] = 65535U;
last++;
}
}
#endif /* 16BIT */
/* Build a single 8-bit table: same as the 16-bit case but much simpler (and
* typically much faster). Note that libpng currently does no sBIT processing
* (apparently contrary to the spec) so a 256-entry table is always generated.
*/
static void
png_build_8bit_table(png_structrp png_ptr, png_bytepp ptable,
PNG_CONST png_fixed_point gamma_val)
{
unsigned int i;
png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256);
if (png_gamma_significant(gamma_val) != 0)
for (i=0; i<256; i++)
table[i] = png_gamma_8bit_correct(i, gamma_val);
else
for (i=0; i<256; ++i)
table[i] = (png_byte)i;
}
/* Used from png_read_destroy and below to release the memory used by the gamma
* tables.
*/
void /* PRIVATE */
png_destroy_gamma_table(png_structrp png_ptr)
{
png_free(png_ptr, png_ptr->gamma_table);
png_ptr->gamma_table = NULL;
#ifdef PNG_16BIT_SUPPORTED
if (png_ptr->gamma_16_table != NULL)
{
int i;
int istop = (1 << (8 - png_ptr->gamma_shift));
for (i = 0; i < istop; i++)
{
png_free(png_ptr, png_ptr->gamma_16_table[i]);
}
png_free(png_ptr, png_ptr->gamma_16_table);
png_ptr->gamma_16_table = NULL;
}
#endif /* 16BIT */
#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
png_free(png_ptr, png_ptr->gamma_from_1);
png_ptr->gamma_from_1 = NULL;
png_free(png_ptr, png_ptr->gamma_to_1);
png_ptr->gamma_to_1 = NULL;
#ifdef PNG_16BIT_SUPPORTED
if (png_ptr->gamma_16_from_1 != NULL)
{
int i;
int istop = (1 << (8 - png_ptr->gamma_shift));
for (i = 0; i < istop; i++)
{
png_free(png_ptr, png_ptr->gamma_16_from_1[i]);
}
png_free(png_ptr, png_ptr->gamma_16_from_1);
png_ptr->gamma_16_from_1 = NULL;
}
if (png_ptr->gamma_16_to_1 != NULL)
{
int i;
int istop = (1 << (8 - png_ptr->gamma_shift));
for (i = 0; i < istop; i++)
{
png_free(png_ptr, png_ptr->gamma_16_to_1[i]);
}
png_free(png_ptr, png_ptr->gamma_16_to_1);
png_ptr->gamma_16_to_1 = NULL;
}
#endif /* 16BIT */
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
}
/* We build the 8- or 16-bit gamma tables here. Note that for 16-bit
* tables, we don't make a full table if we are reducing to 8-bit in
* the future. Note also how the gamma_16 tables are segmented so that
* we don't need to allocate > 64K chunks for a full 16-bit table.
*/
void /* PRIVATE */
png_build_gamma_table(png_structrp png_ptr, int bit_depth)
{
png_debug(1, "in png_build_gamma_table");
/* Remove any existing table; this copes with multiple calls to
* png_read_update_info. The warning is because building the gamma tables
* multiple times is a performance hit - it's harmless but the ability to call
* png_read_update_info() multiple times is new in 1.5.6 so it seems sensible
* to warn if the app introduces such a hit.
*/
if (png_ptr->gamma_table != NULL || png_ptr->gamma_16_table != NULL)
{
png_warning(png_ptr, "gamma table being rebuilt");
png_destroy_gamma_table(png_ptr);
}
if (bit_depth <= 8)
{
png_build_8bit_table(png_ptr, &png_ptr->gamma_table,
png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma,
png_ptr->screen_gamma) : PNG_FP_1);
#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
{
png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1,
png_reciprocal(png_ptr->colorspace.gamma));
png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1,
png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
}
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
}
#ifdef PNG_16BIT_SUPPORTED
else
{
png_byte shift, sig_bit;
if ((png_ptr->color_type & PNG_COLOR_MASK_COLOR) != 0)
{
sig_bit = png_ptr->sig_bit.red;
if (png_ptr->sig_bit.green > sig_bit)
sig_bit = png_ptr->sig_bit.green;
if (png_ptr->sig_bit.blue > sig_bit)
sig_bit = png_ptr->sig_bit.blue;
}
else
sig_bit = png_ptr->sig_bit.gray;
/* 16-bit gamma code uses this equation:
*
* ov = table[(iv & 0xff) >> gamma_shift][iv >> 8]
*
* Where 'iv' is the input color value and 'ov' is the output value -
* pow(iv, gamma).
*
* Thus the gamma table consists of up to 256 256-entry tables. The table
* is selected by the (8-gamma_shift) most significant of the low 8 bits of
* the color value then indexed by the upper 8 bits:
*
* table[low bits][high 8 bits]
*
* So the table 'n' corresponds to all those 'iv' of:
*
* <all high 8-bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1>
*
*/
if (sig_bit > 0 && sig_bit < 16U)
shift = (png_byte)(16U - sig_bit); /* shift == insignificant bits */
else
shift = 0; /* keep all 16 bits */
if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
{
/* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively
* the significant bits in the *input* when the output will
* eventually be 8 bits. By default it is 11.
*/
if (shift < (16U - PNG_MAX_GAMMA_8))
shift = (16U - PNG_MAX_GAMMA_8);
}
if (shift > 8U)
shift = 8U; /* Guarantees at least one table! */
png_ptr->gamma_shift = shift;
/* NOTE: prior to 1.5.4 this test used to include PNG_BACKGROUND (now
* PNG_COMPOSE). This effectively smashed the background calculation for
* 16-bit output because the 8-bit table assumes the result will be reduced
* to 8 bits.
*/
if ((png_ptr->transformations & (PNG_16_TO_8 | PNG_SCALE_16_TO_8)) != 0)
png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift,
png_ptr->screen_gamma > 0 ? png_product2(png_ptr->colorspace.gamma,
png_ptr->screen_gamma) : PNG_FP_1);
else
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift,
png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->colorspace.gamma,
png_ptr->screen_gamma) : PNG_FP_1);
#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
if ((png_ptr->transformations & (PNG_COMPOSE | PNG_RGB_TO_GRAY)) != 0)
{
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift,
png_reciprocal(png_ptr->colorspace.gamma));
/* Notice that the '16 from 1' table should be full precision, however
* the lookup on this table still uses gamma_shift, so it can't be.
* TODO: fix this.
*/
png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift,
png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) :
png_ptr->colorspace.gamma/* Probably doing rgb_to_gray */);
}
#endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
}
#endif /* 16BIT */
}
#endif /* READ_GAMMA */
/* HARDWARE OR SOFTWARE OPTION SUPPORT */
#ifdef PNG_SET_OPTION_SUPPORTED
int PNGAPI
png_set_option(png_structrp png_ptr, int option, int onoff)
{
if (png_ptr != NULL && option >= 0 && option < PNG_OPTION_NEXT &&
(option & 1) == 0)
{
int mask = 3 << option;
int setting = (2 + (onoff != 0)) << option;
int current = png_ptr->options;
png_ptr->options = (png_byte)((current & ~mask) | setting);
return (current & mask) >> option;
}
return PNG_OPTION_INVALID;
}
#endif
/* sRGB support */
#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
/* sRGB conversion tables; these are machine generated with the code in
* contrib/tools/makesRGB.c. The actual sRGB transfer curve defined in the
* specification (see the article at http://en.wikipedia.org/wiki/SRGB)
* is used, not the gamma=1/2.2 approximation use elsewhere in libpng.
* The sRGB to linear table is exact (to the nearest 16 bit linear fraction).
* The inverse (linear to sRGB) table has accuracies as follows:
*
* For all possible (255*65535+1) input values:
*
* error: -0.515566 - 0.625971, 79441 (0.475369%) of readings inexact
*
* For the input values corresponding to the 65536 16-bit values:
*
* error: -0.513727 - 0.607759, 308 (0.469978%) of readings inexact
*
* In all cases the inexact readings are only off by one.
*/
#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
/* The convert-to-sRGB table is only currently required for read. */
const png_uint_16 png_sRGB_table[256] =
{
0,20,40,60,80,99,119,139,
159,179,199,219,241,264,288,313,
340,367,396,427,458,491,526,562,
599,637,677,718,761,805,851,898,
947,997,1048,1101,1156,1212,1270,1330,
1391,1453,1517,1583,1651,1720,1790,1863,
1937,2013,2090,2170,2250,2333,2418,2504,
2592,2681,2773,2866,2961,3058,3157,3258,
3360,3464,3570,3678,3788,3900,4014,4129,
src/Source/LibPNG/png.c view on Meta::CPAN
48850,49344,49841,50341,50844,51349,51858,52369,
52884,53401,53921,54445,54971,55500,56032,56567,
57105,57646,58190,58737,59287,59840,60396,60955,
61517,62082,62650,63221,63795,64372,64952,65535
};
#endif /* SIMPLIFIED_READ */
/* The base/delta tables are required for both read and write (but currently
* only the simplified versions.)
*/
const png_uint_16 png_sRGB_base[512] =
{
128,1782,3383,4644,5675,6564,7357,8074,
8732,9346,9921,10463,10977,11466,11935,12384,
12816,13233,13634,14024,14402,14769,15125,15473,
15812,16142,16466,16781,17090,17393,17690,17981,
18266,18546,18822,19093,19359,19621,19879,20133,
20383,20630,20873,21113,21349,21583,21813,22041,
22265,22487,22707,22923,23138,23350,23559,23767,
23972,24175,24376,24575,24772,24967,25160,25352,
25542,25730,25916,26101,26284,26465,26645,26823,
src/Source/LibPNG/png.c view on Meta::CPAN
61788,61848,61909,61969,62030,62090,62150,62211,
62271,62331,62391,62450,62510,62570,62630,62689,
62749,62808,62867,62927,62986,63045,63104,63163,
63222,63281,63340,63398,63457,63515,63574,63632,
63691,63749,63807,63865,63923,63981,64039,64097,
64155,64212,64270,64328,64385,64443,64500,64557,
64614,64672,64729,64786,64843,64900,64956,65013,
65070,65126,65183,65239,65296,65352,65409,65465
};
const png_byte png_sRGB_delta[512] =
{
207,201,158,129,113,100,90,82,77,72,68,64,61,59,56,54,
52,50,49,47,46,45,43,42,41,40,39,39,38,37,36,36,
35,34,34,33,33,32,32,31,31,30,30,30,29,29,28,28,
28,27,27,27,27,26,26,26,25,25,25,25,24,24,24,24,
23,23,23,23,23,22,22,22,22,22,22,21,21,21,21,21,
21,20,20,20,20,20,20,20,20,19,19,19,19,19,19,19,
19,18,18,18,18,18,18,18,18,18,18,17,17,17,17,17,
17,17,17,17,17,17,16,16,16,16,16,16,16,16,16,16,
16,16,16,16,15,15,15,15,15,15,15,15,15,15,15,15,
src/Source/LibPNG/png.c view on Meta::CPAN
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,
7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
};
#endif /* SIMPLIFIED READ/WRITE sRGB support */
/* SIMPLIFIED READ/WRITE SUPPORT */
#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
static int
png_image_free_function(png_voidp argument)
{
png_imagep image = png_voidcast(png_imagep, argument);
png_controlp cp = image->opaque;
png_control c;
/* Double check that we have a png_ptr - it should be impossible to get here
* without one.
*/
if (cp->png_ptr == NULL)
return 0;
/* First free any data held in the control structure. */
# ifdef PNG_STDIO_SUPPORTED
if (cp->owned_file != 0)
{
FILE *fp = png_voidcast(FILE*, cp->png_ptr->io_ptr);
cp->owned_file = 0;
/* Ignore errors here. */
if (fp != NULL)
{
cp->png_ptr->io_ptr = NULL;
(void)fclose(fp);
}
}
# endif
/* Copy the control structure so that the original, allocated, version can be
* safely freed. Notice that a png_error here stops the remainder of the
* cleanup, but this is probably fine because that would indicate bad memory
* problems anyway.
*/
c = *cp;
image->opaque = &c;
png_free(c.png_ptr, cp);
/* Then the structures, calling the correct API. */
if (c.for_write != 0)
{
# ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
png_destroy_write_struct(&c.png_ptr, &c.info_ptr);
# else
png_error(c.png_ptr, "simplified write not supported");
# endif
}
else
{
# ifdef PNG_SIMPLIFIED_READ_SUPPORTED
png_destroy_read_struct(&c.png_ptr, &c.info_ptr, NULL);
# else
png_error(c.png_ptr, "simplified read not supported");
# endif
}
/* Success. */
return 1;
}
void PNGAPI
png_image_free(png_imagep image)
{
/* Safely call the real function, but only if doing so is safe at this point
* (if not inside an error handling context). Otherwise assume
* png_safe_execute will call this API after the return.
*/
if (image != NULL && image->opaque != NULL &&
image->opaque->error_buf == NULL)
{
/* Ignore errors here: */
(void)png_safe_execute(image, png_image_free_function, image);
image->opaque = NULL;
}
}
int /* PRIVATE */
png_image_error(png_imagep image, png_const_charp error_message)
{
/* Utility to log an error. */
png_safecat(image->message, (sizeof image->message), 0, error_message);
image->warning_or_error |= PNG_IMAGE_ERROR;
png_image_free(image);
return 0;
}
#endif /* SIMPLIFIED READ/WRITE */
#endif /* READ || WRITE */
src/Source/LibPNG/png.h view on Meta::CPAN
/* png.h - header file for PNG reference library
*
* libpng version 1.6.16, December 22, 2014
* Copyright (c) 1998-2014 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
* This code is released under the libpng license (See LICENSE, below)
*
* Authors and maintainers:
* libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
* libpng versions 0.89c, June 1996, through 0.96, May 1997: Andreas Dilger
* libpng versions 0.97, January 1998, through 1.6.16, December 22, 2014: Glenn
* See also "Contributing Authors", below.
*
* Note about libpng version numbers:
*
* Due to various miscommunications, unforeseen code incompatibilities
* and occasional factors outside the authors' control, version numbering
* on the library has not always been consistent and straightforward.
* The following table summarizes matters since version 0.89c, which was
* the first widely used release:
*
* source png.h png.h shared-lib
* version string int version
* ------- ------ ----- ----------
* 0.89c "1.0 beta 3" 0.89 89 1.0.89
* 0.90 "1.0 beta 4" 0.90 90 0.90 [should have been 2.0.90]
* 0.95 "1.0 beta 5" 0.95 95 0.95 [should have been 2.0.95]
* 0.96 "1.0 beta 6" 0.96 96 0.96 [should have been 2.0.96]
* 0.97b "1.00.97 beta 7" 1.00.97 97 1.0.1 [should have been 2.0.97]
* 0.97c 0.97 97 2.0.97
* 0.98 0.98 98 2.0.98
* 0.99 0.99 98 2.0.99
* 0.99a-m 0.99 99 2.0.99
* 1.00 1.00 100 2.1.0 [100 should be 10000]
* 1.0.0 (from here on, the 100 2.1.0 [100 should be 10000]
* 1.0.1 png.h string is 10001 2.1.0
* 1.0.1a-e identical to the 10002 from here on, the shared library
* 1.0.2 source version) 10002 is 2.V where V is the source code
* 1.0.2a-b 10003 version, except as noted.
* 1.0.3 10003
* 1.0.3a-d 10004
* 1.0.4 10004
* 1.0.4a-f 10005
* 1.0.5 (+ 2 patches) 10005
* 1.0.5a-d 10006
* 1.0.5e-r 10100 (not source compatible)
src/Source/LibPNG/png.h view on Meta::CPAN
* 1.6.15beta01-08 16 10615 16.so.16.15[.0]
* 1.6.15rc01-03 16 10615 16.so.16.15[.0]
* 1.6.15 16 10615 16.so.16.15[.0]
* 1.6.16beta01-03 16 10616 16.so.16.16[.0]
* 1.6.16rc01-02 16 10616 16.so.16.16[.0]
* 1.6.16 16 10616 16.so.16.16[.0]
*
* Henceforth the source version will match the shared-library major
* and minor numbers; the shared-library major version number will be
* used for changes in backward compatibility, as it is intended. The
* PNG_LIBPNG_VER macro, which is not used within libpng but is available
* for applications, is an unsigned integer of the form xyyzz corresponding
* to the source version x.y.z (leading zeros in y and z). Beta versions
* were given the previous public release number plus a letter, until
* version 1.0.6j; from then on they were given the upcoming public
* release number plus "betaNN" or "rcNN".
*
* Binary incompatibility exists only when applications make direct access
* to the info_ptr or png_ptr members through png.h, and the compiled
* application is loaded with a different version of the library.
*
* DLLNUM will change each time there are forward or backward changes
* in binary compatibility (e.g., when a new feature is added).
*
* See libpng-manual.txt or libpng.3 for more information. The PNG
* specification is available as a W3C Recommendation and as an ISO
* Specification, <http://www.w3.org/TR/2003/REC-PNG-20031110/
*/
/*
* COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
*
* If you modify libpng you may insert additional notices immediately following
* this sentence.
*
* This code is released under the libpng license.
*
* libpng versions 1.2.6, August 15, 2004, through 1.6.16, December 22, 2014, are
* Copyright (c) 2004, 2006-2014 Glenn Randers-Pehrson, and are
* distributed according to the same disclaimer and license as libpng-1.2.5
* with the following individual added to the list of Contributing Authors:
*
* Cosmin Truta
*
* libpng versions 1.0.7, July 1, 2000, through 1.2.5, October 3, 2002, are
* Copyright (c) 2000-2002 Glenn Randers-Pehrson, and are
* distributed according to the same disclaimer and license as libpng-1.0.6
* with the following individuals added to the list of Contributing Authors:
*
* Simon-Pierre Cadieux
* Eric S. Raymond
* Gilles Vollant
*
* and with the following additions to the disclaimer:
*
* There is no warranty against interference with your enjoyment of the
* library or against infringement. There is no warranty that our
* efforts or the library will fulfill any of your particular purposes
* or needs. This library is provided with all faults, and the entire
* risk of satisfactory quality, performance, accuracy, and effort is with
* the user.
*
* libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
* Copyright (c) 1998, 1999, 2000 Glenn Randers-Pehrson, and are
* distributed according to the same disclaimer and license as libpng-0.96,
* with the following individuals added to the list of Contributing Authors:
*
* Tom Lane
* Glenn Randers-Pehrson
* Willem van Schaik
*
* libpng versions 0.89, June 1996, through 0.96, May 1997, are
* Copyright (c) 1996, 1997 Andreas Dilger
* Distributed according to the same disclaimer and license as libpng-0.88,
* with the following individuals added to the list of Contributing Authors:
*
* John Bowler
* Kevin Bracey
* Sam Bushell
* Magnus Holmgren
* Greg Roelofs
* Tom Tanner
*
* libpng versions 0.5, May 1995, through 0.88, January 1996, are
* Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
*
* For the purposes of this copyright and license, "Contributing Authors"
* is defined as the following set of individuals:
*
* Andreas Dilger
* Dave Martindale
* Guy Eric Schalnat
* Paul Schmidt
* Tim Wegner
src/Source/LibPNG/png.h view on Meta::CPAN
* any source or altered source distribution.
*
* The Contributing Authors and Group 42, Inc. specifically permit, without
* fee, and encourage the use of this source code as a component to
* supporting the PNG file format in commercial products. If you use this
* source code in a product, acknowledgment is not required but would be
* appreciated.
*/
/*
* A "png_get_copyright" function is available, for convenient use in "about"
* boxes and the like:
*
* printf("%s", png_get_copyright(NULL));
*
* Also, the PNG logo (in PNG format, of course) is supplied in the
* files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
*/
/*
* Libpng is OSI Certified Open Source Software. OSI Certified is a
* certification mark of the Open Source Initiative.
*/
/*
* The contributing authors would like to thank all those who helped
* with testing, bug fixes, and patience. This wouldn't have been
* possible without all of you.
*
* Thanks to Frank J. T. Wojcik for helping with the documentation.
*/
/*
* Y2K compliance in libpng:
* =========================
*
* December 22, 2014
*
* Since the PNG Development group is an ad-hoc body, we can't make
* an official declaration.
*
* This is your unofficial assurance that libpng from version 0.71 and
* upward through 1.6.16 are Y2K compliant. It is my belief that
* earlier versions were also Y2K compliant.
*
* Libpng only has two year fields. One is a 2-byte unsigned integer
* that will hold years up to 65535. The other, which is deprecated,
* holds the date in text format, and will hold years up to 9999.
*
* The integer is
* "png_uint_16 year" in png_time_struct.
*
* The string is
* "char time_buffer[29]" in png_struct. This is no longer used
* in libpng-1.6.x and will be removed from libpng-1.7.0.
*
* There are seven time-related functions:
* png.c: png_convert_to_rfc_1123_buffer() in png.c
* (formerly png_convert_to_rfc_1123() prior to libpng-1.5.x and
* png_convert_to_rfc_1152() in error prior to libpng-0.98)
* png_convert_from_struct_tm() in pngwrite.c, called in pngwrite.c
* png_convert_from_time_t() in pngwrite.c
* png_get_tIME() in pngget.c
* png_handle_tIME() in pngrutil.c, called in pngread.c
* png_set_tIME() in pngset.c
* png_write_tIME() in pngwutil.c, called in pngwrite.c
*
* All handle dates properly in a Y2K environment. The
* png_convert_from_time_t() function calls gmtime() to convert from system
* clock time, which returns (year - 1900), which we properly convert to
* the full 4-digit year. There is a possibility that libpng applications
* are not passing 4-digit years into the png_convert_to_rfc_1123_buffer()
* function, or that they are incorrectly passing only a 2-digit year
* instead of "year - 1900" into the png_convert_from_struct_tm() function,
* but this is not under our control. The libpng documentation has always
* stated that it works with 4-digit years, and the APIs have been
* documented as such.
*
* The tIME chunk itself is also Y2K compliant. It uses a 2-byte unsigned
* integer to hold the year, and can hold years as large as 65535.
*
* zlib, upon which libpng depends, is also Y2K compliant. It contains
* no date-related code.
*
* Glenn Randers-Pehrson
* libpng maintainer
* PNG Development Group
*/
#ifndef PNG_H
#define PNG_H
/* This is not the place to learn how to use libpng. The file libpng-manual.txt
* describes how to use libpng, and the file example.c summarizes it
* with some code on which to build. This file is useful for looking
* at the actual function definitions and structure components. If that
* file has been stripped from your copy of libpng, you can find it at
* <http://www.libpng.org/pub/png/libpng-manual.txt>
*
* If you just need to read a PNG file and don't want to read the documentation
* skip to the end of this file and read the section entitled 'simplified API'.
*/
/* Version information for png.h - this should match the version in png.c */
#define PNG_LIBPNG_VER_STRING "1.6.16"
#define PNG_HEADER_VERSION_STRING \
" libpng version 1.6.16 - December 22, 2014\n"
#define PNG_LIBPNG_VER_SONUM 16
#define PNG_LIBPNG_VER_DLLNUM 16
/* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
#define PNG_LIBPNG_VER_MAJOR 1
#define PNG_LIBPNG_VER_MINOR 6
#define PNG_LIBPNG_VER_RELEASE 16
/* This should match the numeric part of the final component of
src/Source/LibPNG/png.h view on Meta::CPAN
* Versions 0.7 through 1.0.0 were in the range 0 to 100 here (only
* version 1.0.0 was mis-numbered 100 instead of 10000). From
* version 1.0.1 it's xxyyzz, where x=major, y=minor, z=release
*/
#define PNG_LIBPNG_VER 10616 /* 1.6.16 */
/* Library configuration: these options cannot be changed after
* the library has been built.
*/
#ifndef PNGLCONF_H
/* If pnglibconf.h is missing, you can
* copy scripts/pnglibconf.h.prebuilt to pnglibconf.h
*/
# include "pnglibconf.h"
#endif
#ifndef PNG_VERSION_INFO_ONLY
/* Machine specific configuration. */
# include "pngconf.h"
#endif
/*
* Added at libpng-1.2.8
*
* Ref MSDN: Private as priority over Special
* VS_FF_PRIVATEBUILD File *was not* built using standard release
* procedures. If this value is given, the StringFileInfo block must
* contain a PrivateBuild string.
*
* VS_FF_SPECIALBUILD File *was* built by the original company using
* standard release procedures but is a variation of the standard
* file of the same version number. If this value is given, the
* StringFileInfo block must contain a SpecialBuild string.
*/
#ifdef PNG_USER_PRIVATEBUILD /* From pnglibconf.h */
# define PNG_LIBPNG_BUILD_TYPE \
(PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_PRIVATE)
#else
# ifdef PNG_LIBPNG_SPECIALBUILD
# define PNG_LIBPNG_BUILD_TYPE \
(PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_SPECIAL)
# else
# define PNG_LIBPNG_BUILD_TYPE (PNG_LIBPNG_BUILD_BASE_TYPE)
# endif
#endif
#ifndef PNG_VERSION_INFO_ONLY
/* Inhibit C++ name-mangling for libpng functions but not for system calls. */
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
/* Version information for C files, stored in png.c. This had better match
* the version above.
*/
#define png_libpng_ver png_get_header_ver(NULL)
/* This file is arranged in several sections:
*
* 1. Any configuration options that can be specified by for the application
* code when it is built. (Build time configuration is in pnglibconf.h)
* 2. Type definitions (base types are defined in pngconf.h), structure
* definitions.
* 3. Exported library functions.
* 4. Simplified API.
*
* The library source code has additional files (principally pngpriv.h) that
* allow configuration of the library.
*/
/* Section 1: run time configuration
* See pnglibconf.h for build time configuration
*
* Run time configuration allows the application to choose between
* implementations of certain arithmetic APIs. The default is set
* at build time and recorded in pnglibconf.h, but it is safe to
* override these (and only these) settings. Note that this won't
* change what the library does, only application code, and the
* settings can (and probably should) be made on a per-file basis
* by setting the #defines before including png.h
*
* Use macros to read integers from PNG data or use the exported
* functions?
* PNG_USE_READ_MACROS: use the macros (see below) Note that
* the macros evaluate their argument multiple times.
* PNG_NO_USE_READ_MACROS: call the relevant library function.
*
* Use the alternative algorithm for compositing alpha samples that
* does not use division?
* PNG_READ_COMPOSITE_NODIV_SUPPORTED: use the 'no division'
* algorithm.
* PNG_NO_READ_COMPOSITE_NODIV: use the 'division' algorithm.
*
* How to handle benign errors if PNG_ALLOW_BENIGN_ERRORS is
* false?
* PNG_ALLOW_BENIGN_ERRORS: map calls to the benign error
* APIs to png_warning.
* Otherwise the calls are mapped to png_error.
*/
/* Section 2: type definitions, including structures and compile time
* constants.
* See pngconf.h for base types that vary by machine/system
*/
/* This triggers a compiler error in png.c, if png.c and png.h
* do not agree upon the version number.
*/
typedef char* png_libpng_version_1_6_16;
/* Basic control structions. Read libpng-manual.txt or libpng.3 for more info.
*
* png_struct is the cache of information used while reading or writing a single
* PNG file. One of these is always required, although the simplified API
* (below) hides the creation and destruction of it.
*/
typedef struct png_struct_def png_struct;
typedef const png_struct * png_const_structp;
typedef png_struct * png_structp;
typedef png_struct * * png_structpp;
/* png_info contains information read from or to be written to a PNG file. One
* or more of these must exist while reading or creating a PNG file. The
* information is not used by libpng during read but is used to control what
* gets written when a PNG file is created. "png_get_" function calls read
* information during read and "png_set_" functions calls write information
* when creating a PNG.
* been moved into a separate header file that is not accessible to
* applications. Read libpng-manual.txt or libpng.3 for more info.
*/
typedef struct png_info_def png_info;
typedef png_info * png_infop;
typedef const png_info * png_const_infop;
typedef png_info * * png_infopp;
/* Types with names ending 'p' are pointer types. The corresponding types with
* names ending 'rp' are identical pointer types except that the pointer is
* marked 'restrict', which means that it is the only pointer to the object
* passed to the function. Applications should not use the 'restrict' types;
* it is always valid to pass 'p' to a pointer with a function argument of the
* corresponding 'rp' type. Different compilers have different rules with
* regard to type matching in the presence of 'restrict'. For backward
* compatibility libpng callbacks never have 'restrict' in their parameters and,
* consequentially, writing portable application code is extremely difficult if
* an attempt is made to use 'restrict'.
*/
typedef png_struct * PNG_RESTRICT png_structrp;
typedef const png_struct * PNG_RESTRICT png_const_structrp;
typedef png_info * PNG_RESTRICT png_inforp;
typedef const png_info * PNG_RESTRICT png_const_inforp;
/* Three color definitions. The order of the red, green, and blue, (and the
* exact size) is not important, although the size of the fields need to
* be png_byte or png_uint_16 (as defined below).
*/
typedef struct png_color_struct
{
png_byte red;
png_byte green;
png_byte blue;
} png_color;
typedef png_color * png_colorp;
typedef const png_color * png_const_colorp;
typedef png_color * * png_colorpp;
typedef struct png_color_16_struct
{
png_byte index; /* used for palette files */
png_uint_16 red; /* for use in red green blue files */
png_uint_16 green;
png_uint_16 blue;
png_uint_16 gray; /* for use in grayscale files */
} png_color_16;
typedef png_color_16 * png_color_16p;
typedef const png_color_16 * png_const_color_16p;
typedef png_color_16 * * png_color_16pp;
typedef struct png_color_8_struct
{
png_byte red; /* for use in red green blue files */
png_byte green;
png_byte blue;
png_byte gray; /* for use in grayscale files */
png_byte alpha; /* for alpha channel files */
} png_color_8;
typedef png_color_8 * png_color_8p;
typedef const png_color_8 * png_const_color_8p;
typedef png_color_8 * * png_color_8pp;
/*
* The following two structures are used for the in-core representation
* of sPLT chunks.
*/
typedef struct png_sPLT_entry_struct
{
png_uint_16 red;
png_uint_16 green;
png_uint_16 blue;
png_uint_16 alpha;
png_uint_16 frequency;
} png_sPLT_entry;
typedef png_sPLT_entry * png_sPLT_entryp;
typedef const png_sPLT_entry * png_const_sPLT_entryp;
typedef png_sPLT_entry * * png_sPLT_entrypp;
/* When the depth of the sPLT palette is 8 bits, the color and alpha samples
* occupy the LSB of their respective members, and the MSB of each member
* is zero-filled. The frequency member always occupies the full 16 bits.
*/
typedef struct png_sPLT_struct
{
png_charp name; /* palette name */
png_byte depth; /* depth of palette samples */
png_sPLT_entryp entries; /* palette entries */
png_int_32 nentries; /* number of palette entries */
} png_sPLT_t;
typedef png_sPLT_t * png_sPLT_tp;
typedef const png_sPLT_t * png_const_sPLT_tp;
typedef png_sPLT_t * * png_sPLT_tpp;
#ifdef PNG_TEXT_SUPPORTED
/* png_text holds the contents of a text/ztxt/itxt chunk in a PNG file,
* and whether that contents is compressed or not. The "key" field
* points to a regular zero-terminated C string. The "text" fields can be a
* regular C string, an empty string, or a NULL pointer.
* However, the structure returned by png_get_text() will always contain
* the "text" field as a regular zero-terminated C string (possibly
* empty), never a NULL pointer, so it can be safely used in printf() and
* other string-handling functions. Note that the "itxt_length", "lang", and
* "lang_key" members of the structure only exist when the library is built
* with iTXt chunk support. Prior to libpng-1.4.0 the library was built by
* default without iTXt support. Also note that when iTXt *is* supported,
* the "lang" and "lang_key" fields contain NULL pointers when the
* "compression" field contains * PNG_TEXT_COMPRESSION_NONE or
* PNG_TEXT_COMPRESSION_zTXt. Note that the "compression value" is not the
* same as what appears in the PNG tEXt/zTXt/iTXt chunk's "compression flag"
* which is always 0 or 1, or its "compression method" which is always 0.
*/
typedef struct png_text_struct
{
int compression; /* compression value:
-1: tEXt, none
0: zTXt, deflate
1: iTXt, none
2: iTXt, deflate */
png_charp key; /* keyword, 1-79 character description of "text" */
png_charp text; /* comment, may be an empty string (ie "")
or a NULL pointer */
png_size_t text_length; /* length of the text string */
png_size_t itxt_length; /* length of the itxt string */
png_charp lang; /* language code, 0-79 characters
or a NULL pointer */
png_charp lang_key; /* keyword translated UTF-8 string, 0 or more
chars or a NULL pointer */
} png_text;
typedef png_text * png_textp;
typedef const png_text * png_const_textp;
typedef png_text * * png_textpp;
#endif
/* Supported compression types for text in PNG files (tEXt, and zTXt).
* The values of the PNG_TEXT_COMPRESSION_ defines should NOT be changed. */
#define PNG_TEXT_COMPRESSION_NONE_WR -3
#define PNG_TEXT_COMPRESSION_zTXt_WR -2
#define PNG_TEXT_COMPRESSION_NONE -1
#define PNG_TEXT_COMPRESSION_zTXt 0
#define PNG_ITXT_COMPRESSION_NONE 1
#define PNG_ITXT_COMPRESSION_zTXt 2
#define PNG_TEXT_COMPRESSION_LAST 3 /* Not a valid value */
/* png_time is a way to hold the time in an machine independent way.
* Two conversions are provided, both from time_t and struct tm. There
* is no portable way to convert to either of these structures, as far
* as I know. If you know of a portable way, send it to me. As a side
* note - PNG has always been Year 2000 compliant!
*/
typedef struct png_time_struct
{
png_uint_16 year; /* full year, as in, 1995 */
png_byte month; /* month of year, 1 - 12 */
png_byte day; /* day of month, 1 - 31 */
png_byte hour; /* hour of day, 0 - 23 */
png_byte minute; /* minute of hour, 0 - 59 */
png_byte second; /* second of minute, 0 - 60 (for leap seconds) */
} png_time;
typedef png_time * png_timep;
typedef const png_time * png_const_timep;
typedef png_time * * png_timepp;
#if defined(PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED) ||\
defined(PNG_USER_CHUNKS_SUPPORTED)
/* png_unknown_chunk is a structure to hold queued chunks for which there is
* no specific support. The idea is that we can use this to queue
* up private chunks for output even though the library doesn't actually
* know about their semantics.
*
* The data in the structure is set by libpng on read and used on write.
*/
typedef struct png_unknown_chunk_t
{
png_byte name[5]; /* Textual chunk name with '\0' terminator */
png_byte *data; /* Data, should not be modified on read! */
png_size_t size;
/* On write 'location' must be set using the flag values listed below.
* Notice that on read it is set by libpng however the values stored have
* more bits set than are listed below. Always treat the value as a
* bitmask. On write set only one bit - setting multiple bits may cause the
* chunk to be written in multiple places.
*/
png_byte location; /* mode of operation at read time */
}
png_unknown_chunk;
typedef png_unknown_chunk * png_unknown_chunkp;
typedef const png_unknown_chunk * png_const_unknown_chunkp;
typedef png_unknown_chunk * * png_unknown_chunkpp;
#endif
/* Flag values for the unknown chunk location byte. */
#define PNG_HAVE_IHDR 0x01
#define PNG_HAVE_PLTE 0x02
#define PNG_AFTER_IDAT 0x08
/* Maximum positive integer used in PNG is (2^31)-1 */
#define PNG_UINT_31_MAX ((png_uint_32)0x7fffffffL)
#define PNG_UINT_32_MAX ((png_uint_32)(-1))
#define PNG_SIZE_MAX ((png_size_t)(-1))
/* These are constants for fixed point values encoded in the
* PNG specification manner (x100000)
*/
#define PNG_FP_1 100000
#define PNG_FP_HALF 50000
#define PNG_FP_MAX ((png_fixed_point)0x7fffffffL)
#define PNG_FP_MIN (-PNG_FP_MAX)
/* These describe the color_type field in png_info. */
/* color type masks */
#define PNG_COLOR_MASK_PALETTE 1
#define PNG_COLOR_MASK_COLOR 2
#define PNG_COLOR_MASK_ALPHA 4
/* color types. Note that not all combinations are legal */
#define PNG_COLOR_TYPE_GRAY 0
#define PNG_COLOR_TYPE_PALETTE (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)
#define PNG_COLOR_TYPE_RGB (PNG_COLOR_MASK_COLOR)
#define PNG_COLOR_TYPE_RGB_ALPHA (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA)
src/Source/LibPNG/png.h view on Meta::CPAN
#define PNG_INFO_sRGB 0x0800 /* GR-P, 0.96a */
#define PNG_INFO_iCCP 0x1000 /* ESR, 1.0.6 */
#define PNG_INFO_sPLT 0x2000 /* ESR, 1.0.6 */
#define PNG_INFO_sCAL 0x4000 /* ESR, 1.0.6 */
#define PNG_INFO_IDAT 0x8000 /* ESR, 1.0.6 */
/* This is used for the transformation routines, as some of them
* change these values for the row. It also should enable using
* the routines for other purposes.
*/
typedef struct png_row_info_struct
{
png_uint_32 width; /* width of row */
png_size_t rowbytes; /* number of bytes in row */
png_byte color_type; /* color type of row */
png_byte bit_depth; /* bit depth of row */
png_byte channels; /* number of channels (1, 2, 3, or 4) */
png_byte pixel_depth; /* bits per pixel (depth * channels) */
} png_row_info;
typedef png_row_info * png_row_infop;
typedef png_row_info * * png_row_infopp;
/* These are the function types for the I/O functions and for the functions
* that allow the user to override the default I/O functions with his or her
* own. The png_error_ptr type should match that of user-supplied warning
* and error functions, while the png_rw_ptr type should match that of the
* user read/write data functions. Note that the 'write' function must not
* modify the buffer it is passed. The 'read' function, on the other hand, is
* expected to return the read data in the buffer.
*/
typedef PNG_CALLBACK(void, *png_error_ptr, (png_structp, png_const_charp));
typedef PNG_CALLBACK(void, *png_rw_ptr, (png_structp, png_bytep, png_size_t));
typedef PNG_CALLBACK(void, *png_flush_ptr, (png_structp));
typedef PNG_CALLBACK(void, *png_read_status_ptr, (png_structp, png_uint_32,
int));
typedef PNG_CALLBACK(void, *png_write_status_ptr, (png_structp, png_uint_32,
int));
#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
typedef PNG_CALLBACK(void, *png_progressive_info_ptr, (png_structp, png_infop));
typedef PNG_CALLBACK(void, *png_progressive_end_ptr, (png_structp, png_infop));
/* The following callback receives png_uint_32 row_number, int pass for the
* png_bytep data of the row. When transforming an interlaced image the
* row number is the row number within the sub-image of the interlace pass, so
* the value will increase to the height of the sub-image (not the full image)
* then reset to 0 for the next pass.
*
* Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
* find the output pixel (x,y) given an interlaced sub-image pixel
* (row,col,pass). (See below for these macros.)
*/
typedef PNG_CALLBACK(void, *png_progressive_row_ptr, (png_structp, png_bytep,
png_uint_32, int));
#endif
#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
typedef PNG_CALLBACK(void, *png_user_transform_ptr, (png_structp, png_row_infop,
png_bytep));
#endif
#ifdef PNG_USER_CHUNKS_SUPPORTED
typedef PNG_CALLBACK(int, *png_user_chunk_ptr, (png_structp,
png_unknown_chunkp));
#endif
#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
/* not used anywhere */
/* typedef PNG_CALLBACK(void, *png_unknown_chunk_ptr, (png_structp)); */
#endif
#ifdef PNG_SETJMP_SUPPORTED
/* This must match the function definition in <setjmp.h>, and the application
* must include this before png.h to obtain the definition of jmp_buf. The
* function is required to be PNG_NORETURN, but this is not checked. If the
* function does return the application will crash via an abort() or similar
* system level call.
*
* If you get a warning here while building the library you may need to make
* changes to ensure that pnglibconf.h records the calling convention used by
* your compiler. This may be very difficult - try using a different compiler
* to build the library!
*/
PNG_FUNCTION(void, (PNGCAPI *png_longjmp_ptr), PNGARG((jmp_buf, int)), typedef);
#endif
/* Transform masks for the high-level interface */
#define PNG_TRANSFORM_IDENTITY 0x0000 /* read and write */
#define PNG_TRANSFORM_STRIP_16 0x0001 /* read only */
#define PNG_TRANSFORM_STRIP_ALPHA 0x0002 /* read only */
#define PNG_TRANSFORM_PACKING 0x0004 /* read and write */
#define PNG_TRANSFORM_PACKSWAP 0x0008 /* read and write */
#define PNG_TRANSFORM_EXPAND 0x0010 /* read only */
#define PNG_TRANSFORM_INVERT_MONO 0x0020 /* read and write */
#define PNG_TRANSFORM_SHIFT 0x0040 /* read and write */
#define PNG_TRANSFORM_BGR 0x0080 /* read and write */
#define PNG_TRANSFORM_SWAP_ALPHA 0x0100 /* read and write */
#define PNG_TRANSFORM_SWAP_ENDIAN 0x0200 /* read and write */
#define PNG_TRANSFORM_INVERT_ALPHA 0x0400 /* read and write */
#define PNG_TRANSFORM_STRIP_FILLER 0x0800 /* write only */
/* Added to libpng-1.2.34 */
#define PNG_TRANSFORM_STRIP_FILLER_BEFORE PNG_TRANSFORM_STRIP_FILLER
#define PNG_TRANSFORM_STRIP_FILLER_AFTER 0x1000 /* write only */
/* Added to libpng-1.4.0 */
#define PNG_TRANSFORM_GRAY_TO_RGB 0x2000 /* read only */
/* Added to libpng-1.5.4 */
#define PNG_TRANSFORM_EXPAND_16 0x4000 /* read only */
#define PNG_TRANSFORM_SCALE_16 0x8000 /* read only */
/* Flags for MNG supported features */
#define PNG_FLAG_MNG_EMPTY_PLTE 0x01
#define PNG_FLAG_MNG_FILTER_64 0x04
#define PNG_ALL_MNG_FEATURES 0x05
/* NOTE: prior to 1.5 these functions had no 'API' style declaration,
* this allowed the zlib default functions to be used on Windows
* platforms. In 1.5 the zlib default malloc (which just calls malloc and
* ignores the first argument) should be completely compatible with the
* following.
*/
typedef PNG_CALLBACK(png_voidp, *png_malloc_ptr, (png_structp,
png_alloc_size_t));
typedef PNG_CALLBACK(void, *png_free_ptr, (png_structp, png_voidp));
/* Section 3: exported functions
* Here are the function definitions most commonly used. This is not
* the place to find out how to use libpng. See libpng-manual.txt for the
* full explanation, see example.c for the summary. This just provides
* a simple one line description of the use of each function.
*
* The PNG_EXPORT() and PNG_EXPORTA() macros used below are defined in
* pngconf.h and in the *.dfn files in the scripts directory.
*
* PNG_EXPORT(ordinal, type, name, (args));
*
* ordinal: ordinal that is used while building
* *.def files. The ordinal value is only
* relevant when preprocessing png.h with
* the *.dfn files for building symbol table
* entries, and are removed by pngconf.h.
* type: return type of the function
* name: function name
* args: function arguments, with types
*
* When we wish to append attributes to a function prototype we use
* the PNG_EXPORTA() macro instead.
*
* PNG_EXPORTA(ordinal, type, name, (args), attributes);
*
* ordinal, type, name, and args: same as in PNG_EXPORT().
* attributes: function attributes
*/
/* Returns the version number of the library */
PNG_EXPORT(1, png_uint_32, png_access_version_number, (void));
/* Tell lib we have already handled the first <num_bytes> magic bytes.
* Handling more than 8 bytes from the beginning of the file is an error.
*/
PNG_EXPORT(2, void, png_set_sig_bytes, (png_structrp png_ptr, int num_bytes));
/* Check sig[start] through sig[start + num_to_check - 1] to see if it's a
* PNG file. Returns zero if the supplied bytes match the 8-byte PNG
* signature, and non-zero otherwise. Having num_to_check == 0 or
* start > 7 will always fail (ie return non-zero).
*/
PNG_EXPORT(3, int, png_sig_cmp, (png_const_bytep sig, png_size_t start,
png_size_t num_to_check));
/* Simple signature checking function. This is the same as calling
* png_check_sig(sig, n) := !png_sig_cmp(sig, 0, n).
*/
#define png_check_sig(sig, n) !png_sig_cmp((sig), 0, (n))
/* Allocate and initialize png_ptr struct for reading, and any other memory. */
PNG_EXPORTA(4, png_structp, png_create_read_struct,
(png_const_charp user_png_ver, png_voidp error_ptr,
png_error_ptr error_fn, png_error_ptr warn_fn),
PNG_ALLOCATED);
/* Allocate and initialize png_ptr struct for writing, and any other memory */
PNG_EXPORTA(5, png_structp, png_create_write_struct,
(png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
png_error_ptr warn_fn),
PNG_ALLOCATED);
PNG_EXPORT(6, png_size_t, png_get_compression_buffer_size,
(png_const_structrp png_ptr));
PNG_EXPORT(7, void, png_set_compression_buffer_size, (png_structrp png_ptr,
png_size_t size));
/* Moved from pngconf.h in 1.4.0 and modified to ensure setjmp/longjmp
* match up.
*/
#ifdef PNG_SETJMP_SUPPORTED
/* This function returns the jmp_buf built in to *png_ptr. It must be
* supplied with an appropriate 'longjmp' function to use on that jmp_buf
* unless the default error function is overridden in which case NULL is
* acceptable. The size of the jmp_buf is checked against the actual size
* allocated by the library - the call will return NULL on a mismatch
* indicating an ABI mismatch.
*/
PNG_EXPORT(8, jmp_buf*, png_set_longjmp_fn, (png_structrp png_ptr,
png_longjmp_ptr longjmp_fn, size_t jmp_buf_size));
# define png_jmpbuf(png_ptr) \
(*png_set_longjmp_fn((png_ptr), longjmp, (sizeof (jmp_buf))))
#else
# define png_jmpbuf(png_ptr) \
(LIBPNG_WAS_COMPILED_WITH__PNG_NO_SETJMP)
#endif
/* This function should be used by libpng applications in place of
* longjmp(png_ptr->jmpbuf, val). If longjmp_fn() has been set, it
* will use it; otherwise it will call PNG_ABORT(). This function was
* added in libpng-1.5.0.
*/
PNG_EXPORTA(9, void, png_longjmp, (png_const_structrp png_ptr, int val),
PNG_NORETURN);
#ifdef PNG_READ_SUPPORTED
/* Reset the compression stream */
PNG_EXPORTA(10, int, png_reset_zstream, (png_structrp png_ptr), PNG_DEPRECATED);
#endif
/* New functions added in libpng-1.0.2 (not enabled by default until 1.2.0) */
#ifdef PNG_USER_MEM_SUPPORTED
PNG_EXPORTA(11, png_structp, png_create_read_struct_2,
(png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
png_error_ptr warn_fn,
png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn),
PNG_ALLOCATED);
PNG_EXPORTA(12, png_structp, png_create_write_struct_2,
(png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
png_error_ptr warn_fn,
png_voidp mem_ptr, png_malloc_ptr malloc_fn, png_free_ptr free_fn),
PNG_ALLOCATED);
#endif
/* Write the PNG file signature. */
PNG_EXPORT(13, void, png_write_sig, (png_structrp png_ptr));
/* Write a PNG chunk - size, type, (optional) data, CRC. */
PNG_EXPORT(14, void, png_write_chunk, (png_structrp png_ptr, png_const_bytep
chunk_name, png_const_bytep data, png_size_t length));
/* Write the start of a PNG chunk - length and chunk name. */
PNG_EXPORT(15, void, png_write_chunk_start, (png_structrp png_ptr,
png_const_bytep chunk_name, png_uint_32 length));
/* Write the data of a PNG chunk started with png_write_chunk_start(). */
PNG_EXPORT(16, void, png_write_chunk_data, (png_structrp png_ptr,
png_const_bytep data, png_size_t length));
/* Finish a chunk started with png_write_chunk_start() (includes CRC). */
PNG_EXPORT(17, void, png_write_chunk_end, (png_structrp png_ptr));
/* Allocate and initialize the info structure */
PNG_EXPORTA(18, png_infop, png_create_info_struct, (png_const_structrp png_ptr),
PNG_ALLOCATED);
/* DEPRECATED: this function allowed init structures to be created using the
* default allocation method (typically malloc). Use is deprecated in 1.6.0 and
* the API will be removed in the future.
*/
PNG_EXPORTA(19, void, png_info_init_3, (png_infopp info_ptr,
png_size_t png_info_struct_size), PNG_DEPRECATED);
/* Writes all the PNG information before the image. */
PNG_EXPORT(20, void, png_write_info_before_PLTE,
(png_structrp png_ptr, png_const_inforp info_ptr));
PNG_EXPORT(21, void, png_write_info,
(png_structrp png_ptr, png_const_inforp info_ptr));
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read the information before the actual image data. */
PNG_EXPORT(22, void, png_read_info,
(png_structrp png_ptr, png_inforp info_ptr));
#endif
#ifdef PNG_TIME_RFC1123_SUPPORTED
/* Convert to a US string format: there is no localization support in this
* routine. The original implementation used a 29 character buffer in
* png_struct, this will be removed in future versions.
*/
#if PNG_LIBPNG_VER < 10700
/* To do: remove this from libpng17 (and from libpng17/png.c and pngstruct.h) */
PNG_EXPORTA(23, png_const_charp, png_convert_to_rfc1123, (png_structrp png_ptr,
png_const_timep ptime),PNG_DEPRECATED);
#endif
PNG_EXPORT(241, int, png_convert_to_rfc1123_buffer, (char out[29],
png_const_timep ptime));
#endif
#ifdef PNG_CONVERT_tIME_SUPPORTED
/* Convert from a struct tm to png_time */
PNG_EXPORT(24, void, png_convert_from_struct_tm, (png_timep ptime,
const struct tm * ttime));
/* Convert from time_t to png_time. Uses gmtime() */
PNG_EXPORT(25, void, png_convert_from_time_t, (png_timep ptime, time_t ttime));
#endif /* CONVERT_tIME */
#ifdef PNG_READ_EXPAND_SUPPORTED
/* Expand data to 24-bit RGB, or 8-bit grayscale, with alpha if available. */
PNG_EXPORT(26, void, png_set_expand, (png_structrp png_ptr));
PNG_EXPORT(27, void, png_set_expand_gray_1_2_4_to_8, (png_structrp png_ptr));
PNG_EXPORT(28, void, png_set_palette_to_rgb, (png_structrp png_ptr));
PNG_EXPORT(29, void, png_set_tRNS_to_alpha, (png_structrp png_ptr));
#endif
#ifdef PNG_READ_EXPAND_16_SUPPORTED
/* Expand to 16-bit channels, forces conversion of palette to RGB and expansion
* of a tRNS chunk if present.
*/
PNG_EXPORT(221, void, png_set_expand_16, (png_structrp png_ptr));
#endif
#if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
/* Use blue, green, red order for pixels. */
PNG_EXPORT(30, void, png_set_bgr, (png_structrp png_ptr));
#endif
#ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
/* Expand the grayscale to 24-bit RGB if necessary. */
PNG_EXPORT(31, void, png_set_gray_to_rgb, (png_structrp png_ptr));
#endif
#ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
/* Reduce RGB to grayscale. */
#define PNG_ERROR_ACTION_NONE 1
#define PNG_ERROR_ACTION_WARN 2
#define PNG_ERROR_ACTION_ERROR 3
#define PNG_RGB_TO_GRAY_DEFAULT (-1)/*for red/green coefficients*/
PNG_FP_EXPORT(32, void, png_set_rgb_to_gray, (png_structrp png_ptr,
int error_action, double red, double green))
PNG_FIXED_EXPORT(33, void, png_set_rgb_to_gray_fixed, (png_structrp png_ptr,
int error_action, png_fixed_point red, png_fixed_point green))
PNG_EXPORT(34, png_byte, png_get_rgb_to_gray_status, (png_const_structrp
png_ptr));
#endif
#ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
PNG_EXPORT(35, void, png_build_grayscale_palette, (int bit_depth,
png_colorp palette));
#endif
#ifdef PNG_READ_ALPHA_MODE_SUPPORTED
/* How the alpha channel is interpreted - this affects how the color channels
* of a PNG file are returned to the calling application when an alpha channel,
* or a tRNS chunk in a palette file, is present.
*
* This has no effect on the way pixels are written into a PNG output
* datastream. The color samples in a PNG datastream are never premultiplied
* with the alpha samples.
src/Source/LibPNG/png.h view on Meta::CPAN
* For the 'OPTIMIZED' mode, a pixel is treated as opaque only if the alpha
* value is equal to the maximum value.
*
* The final choice is to gamma encode the alpha channel as well. This is
* broken because, in practice, no implementation that uses this choice
* correctly undoes the encoding before handling alpha composition. Use this
* choice only if other serious errors in the software or hardware you use
* mandate it; the typical serious error is for dark halos to appear around
* opaque areas of the composited PNG image because of arithmetic overflow.
*
* The API function png_set_alpha_mode specifies which of these choices to use
* with an enumerated 'mode' value and the gamma of the required output:
*/
#define PNG_ALPHA_PNG 0 /* according to the PNG standard */
#define PNG_ALPHA_STANDARD 1 /* according to Porter/Duff */
#define PNG_ALPHA_ASSOCIATED 1 /* as above; this is the normal practice */
#define PNG_ALPHA_PREMULTIPLIED 1 /* as above */
#define PNG_ALPHA_OPTIMIZED 2 /* 'PNG' for opaque pixels, else 'STANDARD' */
#define PNG_ALPHA_BROKEN 3 /* the alpha channel is gamma encoded */
PNG_FP_EXPORT(227, void, png_set_alpha_mode, (png_structrp png_ptr, int mode,
double output_gamma))
PNG_FIXED_EXPORT(228, void, png_set_alpha_mode_fixed, (png_structrp png_ptr,
int mode, png_fixed_point output_gamma))
#endif
#if defined(PNG_GAMMA_SUPPORTED) || defined(PNG_READ_ALPHA_MODE_SUPPORTED)
/* The output_gamma value is a screen gamma in libpng terminology: it expresses
* how to decode the output values, not how they are encoded.
*/
#define PNG_DEFAULT_sRGB -1 /* sRGB gamma and color space */
#define PNG_GAMMA_MAC_18 -2 /* Old Mac '1.8' gamma and color space */
#define PNG_GAMMA_sRGB 220000 /* Television standards--matches sRGB gamma */
#define PNG_GAMMA_LINEAR PNG_FP_1 /* Linear */
#endif
/* The following are examples of calls to png_set_alpha_mode to achieve the
* required overall gamma correction and, where necessary, alpha
* premultiplication.
*
* png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
* This is the default libpng handling of the alpha channel - it is not
* pre-multiplied into the color components. In addition the call states
* that the output is for a sRGB system and causes all PNG files without gAMA
* chunks to be assumed to be encoded using sRGB.
*
* png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
* In this case the output is assumed to be something like an sRGB conformant
* display preceeded by a power-law lookup table of power 1.45. This is how
* early Mac systems behaved.
*
* png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_GAMMA_LINEAR);
* This is the classic Jim Blinn approach and will work in academic
* environments where everything is done by the book. It has the shortcoming
* of assuming that input PNG data with no gamma information is linear - this
* is unlikely to be correct unless the PNG files where generated locally.
* Most of the time the output precision will be so low as to show
* significant banding in dark areas of the image.
*
* png_set_expand_16(pp);
* png_set_alpha_mode(pp, PNG_ALPHA_STANDARD, PNG_DEFAULT_sRGB);
* This is a somewhat more realistic Jim Blinn inspired approach. PNG files
* are assumed to have the sRGB encoding if not marked with a gamma value and
* the output is always 16 bits per component. This permits accurate scaling
* and processing of the data. If you know that your input PNG files were
* generated locally you might need to replace PNG_DEFAULT_sRGB with the
* correct value for your system.
*
* png_set_alpha_mode(pp, PNG_ALPHA_OPTIMIZED, PNG_DEFAULT_sRGB);
* If you just need to composite the PNG image onto an existing background
* and if you control the code that does this you can use the optimization
* setting. In this case you just copy completely opaque pixels to the
* output. For pixels that are not completely transparent (you just skip
* those) you do the composition math using png_composite or png_composite_16
* below then encode the resultant 8-bit or 16-bit values to match the output
* encoding.
*
* Other cases
* If neither the PNG nor the standard linear encoding work for you because
* of the software or hardware you use then you have a big problem. The PNG
* case will probably result in halos around the image. The linear encoding
* will probably result in a washed out, too bright, image (it's actually too
* contrasty.) Try the ALPHA_OPTIMIZED mode above - this will probably
* substantially reduce the halos. Alternatively try:
*
* png_set_alpha_mode(pp, PNG_ALPHA_BROKEN, PNG_DEFAULT_sRGB);
* This option will also reduce the halos, but there will be slight dark
* halos round the opaque parts of the image where the background is light.
* In the OPTIMIZED mode the halos will be light halos where the background
* is dark. Take your pick - the halos are unavoidable unless you can get
* your hardware/software fixed! (The OPTIMIZED approach is slightly
* faster.)
*
* When the default gamma of PNG files doesn't match the output gamma.
* If you have PNG files with no gamma information png_set_alpha_mode allows
* you to provide a default gamma, but it also sets the ouput gamma to the
* matching value. If you know your PNG files have a gamma that doesn't
* match the output you can take advantage of the fact that
* png_set_alpha_mode always sets the output gamma but only sets the PNG
* default if it is not already set:
*
* png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_DEFAULT_sRGB);
* png_set_alpha_mode(pp, PNG_ALPHA_PNG, PNG_GAMMA_MAC);
* The first call sets both the default and the output gamma values, the
* second call overrides the output gamma without changing the default. This
* is easier than achieving the same effect with png_set_gamma. You must use
* PNG_ALPHA_PNG for the first call - internal checking in png_set_alpha will
* fire if more than one call to png_set_alpha_mode and png_set_background is
* made in the same read operation, however multiple calls with PNG_ALPHA_PNG
* are ignored.
*/
#ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
PNG_EXPORT(36, void, png_set_strip_alpha, (png_structrp png_ptr));
#endif
#if defined(PNG_READ_SWAP_ALPHA_SUPPORTED) || \
defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
PNG_EXPORT(37, void, png_set_swap_alpha, (png_structrp png_ptr));
#endif
#if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) || \
defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
PNG_EXPORT(38, void, png_set_invert_alpha, (png_structrp png_ptr));
#endif
#if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
/* Add a filler byte to 8-bit Gray or 24-bit RGB images. */
PNG_EXPORT(39, void, png_set_filler, (png_structrp png_ptr, png_uint_32 filler,
int flags));
/* The values of the PNG_FILLER_ defines should NOT be changed */
# define PNG_FILLER_BEFORE 0
# define PNG_FILLER_AFTER 1
/* Add an alpha byte to 8-bit Gray or 24-bit RGB images. */
PNG_EXPORT(40, void, png_set_add_alpha, (png_structrp png_ptr,
png_uint_32 filler, int flags));
#endif /* READ_FILLER || WRITE_FILLER */
#if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
/* Swap bytes in 16-bit depth files. */
PNG_EXPORT(41, void, png_set_swap, (png_structrp png_ptr));
#endif
#if defined(PNG_READ_PACK_SUPPORTED) || defined(PNG_WRITE_PACK_SUPPORTED)
/* Use 1 byte per pixel in 1, 2, or 4-bit depth files. */
PNG_EXPORT(42, void, png_set_packing, (png_structrp png_ptr));
#endif
#if defined(PNG_READ_PACKSWAP_SUPPORTED) || \
defined(PNG_WRITE_PACKSWAP_SUPPORTED)
/* Swap packing order of pixels in bytes. */
PNG_EXPORT(43, void, png_set_packswap, (png_structrp png_ptr));
#endif
#if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
/* Converts files to legal bit depths. */
PNG_EXPORT(44, void, png_set_shift, (png_structrp png_ptr, png_const_color_8p
true_bits));
#endif
#if defined(PNG_READ_INTERLACING_SUPPORTED) || \
defined(PNG_WRITE_INTERLACING_SUPPORTED)
/* Have the code handle the interlacing. Returns the number of passes.
* MUST be called before png_read_update_info or png_start_read_image,
* otherwise it will not have the desired effect. Note that it is still
* necessary to call png_read_row or png_read_rows png_get_image_height
* times for each pass.
*/
PNG_EXPORT(45, int, png_set_interlace_handling, (png_structrp png_ptr));
#endif
#if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
/* Invert monochrome files */
PNG_EXPORT(46, void, png_set_invert_mono, (png_structrp png_ptr));
#endif
#ifdef PNG_READ_BACKGROUND_SUPPORTED
/* Handle alpha and tRNS by replacing with a background color. Prior to
* libpng-1.5.4 this API must not be called before the PNG file header has been
* read. Doing so will result in unexpected behavior and possible warnings or
* errors if the PNG file contains a bKGD chunk.
*/
PNG_FP_EXPORT(47, void, png_set_background, (png_structrp png_ptr,
png_const_color_16p background_color, int background_gamma_code,
int need_expand, double background_gamma))
PNG_FIXED_EXPORT(215, void, png_set_background_fixed, (png_structrp png_ptr,
png_const_color_16p background_color, int background_gamma_code,
int need_expand, png_fixed_point background_gamma))
#endif
#ifdef PNG_READ_BACKGROUND_SUPPORTED
# define PNG_BACKGROUND_GAMMA_UNKNOWN 0
# define PNG_BACKGROUND_GAMMA_SCREEN 1
# define PNG_BACKGROUND_GAMMA_FILE 2
# define PNG_BACKGROUND_GAMMA_UNIQUE 3
#endif
#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
/* Scale a 16-bit depth file down to 8-bit, accurately. */
PNG_EXPORT(229, void, png_set_scale_16, (png_structrp png_ptr));
#endif
#ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
#define PNG_READ_16_TO_8 SUPPORTED /* Name prior to 1.5.4 */
/* Strip the second byte of information from a 16-bit depth file. */
PNG_EXPORT(48, void, png_set_strip_16, (png_structrp png_ptr));
#endif
#ifdef PNG_READ_QUANTIZE_SUPPORTED
/* Turn on quantizing, and reduce the palette to the number of colors
* available.
*/
PNG_EXPORT(49, void, png_set_quantize, (png_structrp png_ptr,
png_colorp palette, int num_palette, int maximum_colors,
png_const_uint_16p histogram, int full_quantize));
#endif
#ifdef PNG_READ_GAMMA_SUPPORTED
/* The threshold on gamma processing is configurable but hard-wired into the
* library. The following is the floating point variant.
*/
#define PNG_GAMMA_THRESHOLD (PNG_GAMMA_THRESHOLD_FIXED*.00001)
/* Handle gamma correction. Screen_gamma=(display_exponent).
* NOTE: this API simply sets the screen and file gamma values. It will
* therefore override the value for gamma in a PNG file if it is called after
* the file header has been read - use with care - call before reading the PNG
* file for best results!
*
* These routines accept the same gamma values as png_set_alpha_mode (described
* above). The PNG_GAMMA_ defines and PNG_DEFAULT_sRGB can be passed to either
* API (floating point or fixed.) Notice, however, that the 'file_gamma' value
* is the inverse of a 'screen gamma' value.
*/
PNG_FP_EXPORT(50, void, png_set_gamma, (png_structrp png_ptr,
double screen_gamma, double override_file_gamma))
PNG_FIXED_EXPORT(208, void, png_set_gamma_fixed, (png_structrp png_ptr,
png_fixed_point screen_gamma, png_fixed_point override_file_gamma))
#endif
#ifdef PNG_WRITE_FLUSH_SUPPORTED
/* Set how many lines between output flushes - 0 for no flushing */
PNG_EXPORT(51, void, png_set_flush, (png_structrp png_ptr, int nrows));
/* Flush the current PNG output buffer */
PNG_EXPORT(52, void, png_write_flush, (png_structrp png_ptr));
#endif
/* Optional update palette with requested transformations */
PNG_EXPORT(53, void, png_start_read_image, (png_structrp png_ptr));
/* Optional call to update the users info structure */
PNG_EXPORT(54, void, png_read_update_info, (png_structrp png_ptr,
png_inforp info_ptr));
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read one or more rows of image data. */
PNG_EXPORT(55, void, png_read_rows, (png_structrp png_ptr, png_bytepp row,
png_bytepp display_row, png_uint_32 num_rows));
#endif
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read a row of data. */
PNG_EXPORT(56, void, png_read_row, (png_structrp png_ptr, png_bytep row,
png_bytep display_row));
#endif
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read the whole image into memory at once. */
PNG_EXPORT(57, void, png_read_image, (png_structrp png_ptr, png_bytepp image));
#endif
/* Write a row of image data */
PNG_EXPORT(58, void, png_write_row, (png_structrp png_ptr,
png_const_bytep row));
/* Write a few rows of image data: (*row) is not written; however, the type
* is declared as writeable to maintain compatibility with previous versions
* of libpng and to allow the 'display_row' array from read_rows to be passed
* unchanged to write_rows.
*/
PNG_EXPORT(59, void, png_write_rows, (png_structrp png_ptr, png_bytepp row,
png_uint_32 num_rows));
/* Write the image data */
PNG_EXPORT(60, void, png_write_image, (png_structrp png_ptr, png_bytepp image));
/* Write the end of the PNG file. */
PNG_EXPORT(61, void, png_write_end, (png_structrp png_ptr,
png_inforp info_ptr));
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read the end of the PNG file. */
PNG_EXPORT(62, void, png_read_end, (png_structrp png_ptr, png_inforp info_ptr));
#endif
/* Free any memory associated with the png_info_struct */
PNG_EXPORT(63, void, png_destroy_info_struct, (png_const_structrp png_ptr,
png_infopp info_ptr_ptr));
/* Free any memory associated with the png_struct and the png_info_structs */
PNG_EXPORT(64, void, png_destroy_read_struct, (png_structpp png_ptr_ptr,
png_infopp info_ptr_ptr, png_infopp end_info_ptr_ptr));
/* Free any memory associated with the png_struct and the png_info_structs */
PNG_EXPORT(65, void, png_destroy_write_struct, (png_structpp png_ptr_ptr,
png_infopp info_ptr_ptr));
/* Set the libpng method of handling chunk CRC errors */
PNG_EXPORT(66, void, png_set_crc_action, (png_structrp png_ptr, int crit_action,
int ancil_action));
/* Values for png_set_crc_action() say how to handle CRC errors in
* ancillary and critical chunks, and whether to use the data contained
* therein. Note that it is impossible to "discard" data in a critical
* chunk. For versions prior to 0.90, the action was always error/quit,
* whereas in version 0.90 and later, the action for CRC errors in ancillary
* chunks is warn/discard. These values should NOT be changed.
*
* value action:critical action:ancillary
*/
#define PNG_CRC_DEFAULT 0 /* error/quit warn/discard data */
#define PNG_CRC_ERROR_QUIT 1 /* error/quit error/quit */
#define PNG_CRC_WARN_DISCARD 2 /* (INVALID) warn/discard data */
#define PNG_CRC_WARN_USE 3 /* warn/use data warn/use data */
#define PNG_CRC_QUIET_USE 4 /* quiet/use data quiet/use data */
#define PNG_CRC_NO_CHANGE 5 /* use current value use current value */
/* These functions give the user control over the scan-line filtering in
* libpng and the compression methods used by zlib. These functions are
* mainly useful for testing, as the defaults should work with most users.
* Those users who are tight on memory or want faster performance at the
* expense of compression can modify them. See the compression library
* header file (zlib.h) for an explination of the compression functions.
*/
/* Set the filtering method(s) used by libpng. Currently, the only valid
* value for "method" is 0.
*/
PNG_EXPORT(67, void, png_set_filter, (png_structrp png_ptr, int method,
int filters));
/* Flags for png_set_filter() to say which filters to use. The flags
* are chosen so that they don't conflict with real filter types
* below, in case they are supplied instead of the #defined constants.
* These values should NOT be changed.
*/
#define PNG_NO_FILTERS 0x00
#define PNG_FILTER_NONE 0x08
#define PNG_FILTER_SUB 0x10
#define PNG_FILTER_UP 0x20
#define PNG_FILTER_AVG 0x40
#define PNG_FILTER_PAETH 0x80
#define PNG_ALL_FILTERS (PNG_FILTER_NONE | PNG_FILTER_SUB | PNG_FILTER_UP | \
PNG_FILTER_AVG | PNG_FILTER_PAETH)
/* Filter values (not flags) - used in pngwrite.c, pngwutil.c for now.
* These defines should NOT be changed.
*/
#define PNG_FILTER_VALUE_NONE 0
#define PNG_FILTER_VALUE_SUB 1
#define PNG_FILTER_VALUE_UP 2
#define PNG_FILTER_VALUE_AVG 3
#define PNG_FILTER_VALUE_PAETH 4
#define PNG_FILTER_VALUE_LAST 5
#ifdef PNG_WRITE_WEIGHTED_FILTER_SUPPORTED /* EXPERIMENTAL */
src/Source/LibPNG/png.h view on Meta::CPAN
* setting the costs. Costs try to improve the speed of decompression without
* unduly increasing the compressed image size.
*
* A negative weight or cost indicates the default value is to be used, and
* values in the range [0.0, 1.0) indicate the value is to remain unchanged.
* The default values for both weights and costs are currently 1.0, but may
* change if good general weighting/cost heuristics can be found. If both
* the weights and costs are set to 1.0, this degenerates the WEIGHTED method
* to the UNWEIGHTED method, but with added encoding time/computation.
*/
PNG_FP_EXPORT(68, void, png_set_filter_heuristics, (png_structrp png_ptr,
int heuristic_method, int num_weights, png_const_doublep filter_weights,
png_const_doublep filter_costs))
PNG_FIXED_EXPORT(209, void, png_set_filter_heuristics_fixed,
(png_structrp png_ptr, int heuristic_method, int num_weights,
png_const_fixed_point_p filter_weights,
png_const_fixed_point_p filter_costs))
#endif /* WRITE_WEIGHTED_FILTER */
/* Heuristic used for row filter selection. These defines should NOT be
* changed.
*/
#define PNG_FILTER_HEURISTIC_DEFAULT 0 /* Currently "UNWEIGHTED" */
#define PNG_FILTER_HEURISTIC_UNWEIGHTED 1 /* Used by libpng < 0.95 */
#define PNG_FILTER_HEURISTIC_WEIGHTED 2 /* Experimental feature */
#define PNG_FILTER_HEURISTIC_LAST 3 /* Not a valid value */
#ifdef PNG_WRITE_SUPPORTED
/* Set the library compression level. Currently, valid values range from
* 0 - 9, corresponding directly to the zlib compression levels 0 - 9
* (0 - no compression, 9 - "maximal" compression). Note that tests have
* shown that zlib compression levels 3-6 usually perform as well as level 9
* for PNG images, and do considerably fewer caclulations. In the future,
* these values may not correspond directly to the zlib compression levels.
*/
PNG_EXPORT(69, void, png_set_compression_level, (png_structrp png_ptr,
int level));
PNG_EXPORT(70, void, png_set_compression_mem_level, (png_structrp png_ptr,
int mem_level));
PNG_EXPORT(71, void, png_set_compression_strategy, (png_structrp png_ptr,
int strategy));
/* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
* smaller value of window_bits if it can do so safely.
*/
PNG_EXPORT(72, void, png_set_compression_window_bits, (png_structrp png_ptr,
int window_bits));
PNG_EXPORT(73, void, png_set_compression_method, (png_structrp png_ptr,
int method));
#endif
#ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
/* Also set zlib parameters for compressing non-IDAT chunks */
PNG_EXPORT(222, void, png_set_text_compression_level, (png_structrp png_ptr,
int level));
PNG_EXPORT(223, void, png_set_text_compression_mem_level, (png_structrp png_ptr,
int mem_level));
PNG_EXPORT(224, void, png_set_text_compression_strategy, (png_structrp png_ptr,
int strategy));
/* If PNG_WRITE_OPTIMIZE_CMF_SUPPORTED is defined, libpng will use a
* smaller value of window_bits if it can do so safely.
*/
PNG_EXPORT(225, void, png_set_text_compression_window_bits,
(png_structrp png_ptr, int window_bits));
PNG_EXPORT(226, void, png_set_text_compression_method, (png_structrp png_ptr,
int method));
#endif /* WRITE_CUSTOMIZE_ZTXT_COMPRESSION */
/* These next functions are called for input/output, memory, and error
* handling. They are in the file pngrio.c, pngwio.c, and pngerror.c,
* and call standard C I/O routines such as fread(), fwrite(), and
* fprintf(). These functions can be made to use other I/O routines
* at run time for those applications that need to handle I/O in a
* different manner by calling png_set_???_fn(). See libpng-manual.txt for
* more information.
*/
#ifdef PNG_STDIO_SUPPORTED
/* Initialize the input/output for the PNG file to the default functions. */
PNG_EXPORT(74, void, png_init_io, (png_structrp png_ptr, png_FILE_p fp));
#endif
/* Replace the (error and abort), and warning functions with user
* supplied functions. If no messages are to be printed you must still
* write and use replacement functions. The replacement error_fn should
* still do a longjmp to the last setjmp location if you are using this
* method of error handling. If error_fn or warning_fn is NULL, the
* default function will be used.
*/
PNG_EXPORT(75, void, png_set_error_fn, (png_structrp png_ptr,
png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warning_fn));
/* Return the user pointer associated with the error functions */
PNG_EXPORT(76, png_voidp, png_get_error_ptr, (png_const_structrp png_ptr));
/* Replace the default data output functions with a user supplied one(s).
* If buffered output is not used, then output_flush_fn can be set to NULL.
* If PNG_WRITE_FLUSH_SUPPORTED is not defined at libpng compile time
* output_flush_fn will be ignored (and thus can be NULL).
* It is probably a mistake to use NULL for output_flush_fn if
* write_data_fn is not also NULL unless you have built libpng with
* PNG_WRITE_FLUSH_SUPPORTED undefined, because in this case libpng's
* default flush function, which uses the standard *FILE structure, will
* be used.
*/
PNG_EXPORT(77, void, png_set_write_fn, (png_structrp png_ptr, png_voidp io_ptr,
png_rw_ptr write_data_fn, png_flush_ptr output_flush_fn));
/* Replace the default data input function with a user supplied one. */
PNG_EXPORT(78, void, png_set_read_fn, (png_structrp png_ptr, png_voidp io_ptr,
png_rw_ptr read_data_fn));
/* Return the user pointer associated with the I/O functions */
PNG_EXPORT(79, png_voidp, png_get_io_ptr, (png_const_structrp png_ptr));
PNG_EXPORT(80, void, png_set_read_status_fn, (png_structrp png_ptr,
png_read_status_ptr read_row_fn));
PNG_EXPORT(81, void, png_set_write_status_fn, (png_structrp png_ptr,
png_write_status_ptr write_row_fn));
#ifdef PNG_USER_MEM_SUPPORTED
/* Replace the default memory allocation functions with user supplied one(s). */
PNG_EXPORT(82, void, png_set_mem_fn, (png_structrp png_ptr, png_voidp mem_ptr,
png_malloc_ptr malloc_fn, png_free_ptr free_fn));
/* Return the user pointer associated with the memory functions */
PNG_EXPORT(83, png_voidp, png_get_mem_ptr, (png_const_structrp png_ptr));
#endif
#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
PNG_EXPORT(84, void, png_set_read_user_transform_fn, (png_structrp png_ptr,
png_user_transform_ptr read_user_transform_fn));
#endif
#ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
PNG_EXPORT(85, void, png_set_write_user_transform_fn, (png_structrp png_ptr,
png_user_transform_ptr write_user_transform_fn));
#endif
#ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
PNG_EXPORT(86, void, png_set_user_transform_info, (png_structrp png_ptr,
png_voidp user_transform_ptr, int user_transform_depth,
int user_transform_channels));
/* Return the user pointer associated with the user transform functions */
PNG_EXPORT(87, png_voidp, png_get_user_transform_ptr,
(png_const_structrp png_ptr));
#endif
#ifdef PNG_USER_TRANSFORM_INFO_SUPPORTED
/* Return information about the row currently being processed. Note that these
* APIs do not fail but will return unexpected results if called outside a user
* transform callback. Also note that when transforming an interlaced image the
* row number is the row number within the sub-image of the interlace pass, so
* the value will increase to the height of the sub-image (not the full image)
* then reset to 0 for the next pass.
*
* Use PNG_ROW_FROM_PASS_ROW(row, pass) and PNG_COL_FROM_PASS_COL(col, pass) to
* find the output pixel (x,y) given an interlaced sub-image pixel
* (row,col,pass). (See below for these macros.)
*/
PNG_EXPORT(217, png_uint_32, png_get_current_row_number, (png_const_structrp));
PNG_EXPORT(218, png_byte, png_get_current_pass_number, (png_const_structrp));
#endif
#ifdef PNG_READ_USER_CHUNKS_SUPPORTED
/* This callback is called only for *unknown* chunks. If
* PNG_HANDLE_AS_UNKNOWN_SUPPORTED is set then it is possible to set known
* chunks to be treated as unknown, however in this case the callback must do
* any processing required by the chunk (e.g. by calling the appropriate
* png_set_ APIs.)
*
* There is no write support - on write, by default, all the chunks in the
* 'unknown' list are written in the specified position.
*
* The integer return from the callback function is interpreted thus:
*
* negative: An error occured, png_chunk_error will be called.
* zero: The chunk was not handled, the chunk will be saved. A critical
* chunk will cause an error at this point unless it is to be saved.
* positive: The chunk was handled, libpng will ignore/discard it.
*
* See "INTERACTION WTIH USER CHUNK CALLBACKS" below for important notes about
* how this behavior will change in libpng 1.7
*/
PNG_EXPORT(88, void, png_set_read_user_chunk_fn, (png_structrp png_ptr,
png_voidp user_chunk_ptr, png_user_chunk_ptr read_user_chunk_fn));
#endif
#ifdef PNG_USER_CHUNKS_SUPPORTED
PNG_EXPORT(89, png_voidp, png_get_user_chunk_ptr, (png_const_structrp png_ptr));
#endif
#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
/* Sets the function callbacks for the push reader, and a pointer to a
* user-defined structure available to the callback functions.
*/
PNG_EXPORT(90, void, png_set_progressive_read_fn, (png_structrp png_ptr,
png_voidp progressive_ptr, png_progressive_info_ptr info_fn,
png_progressive_row_ptr row_fn, png_progressive_end_ptr end_fn));
/* Returns the user pointer associated with the push read functions */
PNG_EXPORT(91, png_voidp, png_get_progressive_ptr,
(png_const_structrp png_ptr));
/* Function to be called when data becomes available */
PNG_EXPORT(92, void, png_process_data, (png_structrp png_ptr,
png_inforp info_ptr, png_bytep buffer, png_size_t buffer_size));
/* A function which may be called *only* within png_process_data to stop the
* processing of any more data. The function returns the number of bytes
* remaining, excluding any that libpng has cached internally. A subsequent
* call to png_process_data must supply these bytes again. If the argument
* 'save' is set to true the routine will first save all the pending data and
* will always return 0.
*/
PNG_EXPORT(219, png_size_t, png_process_data_pause, (png_structrp, int save));
/* A function which may be called *only* outside (after) a call to
* png_process_data. It returns the number of bytes of data to skip in the
* input. Normally it will return 0, but if it returns a non-zero value the
* application must skip than number of bytes of input data and pass the
* following data to the next call to png_process_data.
*/
PNG_EXPORT(220, png_uint_32, png_process_data_skip, (png_structrp));
/* Function that combines rows. 'new_row' is a flag that should come from
* the callback and be non-NULL if anything needs to be done; the library
* stores its own version of the new data internally and ignores the passed
* in value.
*/
PNG_EXPORT(93, void, png_progressive_combine_row, (png_const_structrp png_ptr,
png_bytep old_row, png_const_bytep new_row));
#endif /* PROGRESSIVE_READ */
PNG_EXPORTA(94, png_voidp, png_malloc, (png_const_structrp png_ptr,
png_alloc_size_t size), PNG_ALLOCATED);
/* Added at libpng version 1.4.0 */
PNG_EXPORTA(95, png_voidp, png_calloc, (png_const_structrp png_ptr,
png_alloc_size_t size), PNG_ALLOCATED);
/* Added at libpng version 1.2.4 */
PNG_EXPORTA(96, png_voidp, png_malloc_warn, (png_const_structrp png_ptr,
png_alloc_size_t size), PNG_ALLOCATED);
/* Frees a pointer allocated by png_malloc() */
PNG_EXPORT(97, void, png_free, (png_const_structrp png_ptr, png_voidp ptr));
/* Free data that was allocated internally */
PNG_EXPORT(98, void, png_free_data, (png_const_structrp png_ptr,
png_inforp info_ptr, png_uint_32 free_me, int num));
/* Reassign responsibility for freeing existing data, whether allocated
* by libpng or by the application; this works on the png_info structure passed
* in, it does not change the state for other png_info structures.
*
* It is unlikely that this function works correctly as of 1.6.0 and using it
* may result either in memory leaks or double free of allocated data.
*/
PNG_EXPORT(99, void, png_data_freer, (png_const_structrp png_ptr,
png_inforp info_ptr, int freer, png_uint_32 mask));
/* Assignments for png_data_freer */
#define PNG_DESTROY_WILL_FREE_DATA 1
#define PNG_SET_WILL_FREE_DATA 1
#define PNG_USER_WILL_FREE_DATA 2
/* Flags for png_ptr->free_me and info_ptr->free_me */
#define PNG_FREE_HIST 0x0008
#define PNG_FREE_ICCP 0x0010
#define PNG_FREE_SPLT 0x0020
#define PNG_FREE_ROWS 0x0040
#define PNG_FREE_PCAL 0x0080
#define PNG_FREE_SCAL 0x0100
#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
# define PNG_FREE_UNKN 0x0200
#endif
/* PNG_FREE_LIST 0x0400 removed in 1.6.0 because it is ignored */
#define PNG_FREE_PLTE 0x1000
#define PNG_FREE_TRNS 0x2000
#define PNG_FREE_TEXT 0x4000
#define PNG_FREE_ALL 0x7fff
#define PNG_FREE_MUL 0x4220 /* PNG_FREE_SPLT|PNG_FREE_TEXT|PNG_FREE_UNKN */
#ifdef PNG_USER_MEM_SUPPORTED
PNG_EXPORTA(100, png_voidp, png_malloc_default, (png_const_structrp png_ptr,
png_alloc_size_t size), PNG_ALLOCATED PNG_DEPRECATED);
PNG_EXPORTA(101, void, png_free_default, (png_const_structrp png_ptr,
png_voidp ptr), PNG_DEPRECATED);
#endif
#ifdef PNG_ERROR_TEXT_SUPPORTED
/* Fatal error in PNG image of libpng - can't continue */
PNG_EXPORTA(102, void, png_error, (png_const_structrp png_ptr,
png_const_charp error_message), PNG_NORETURN);
/* The same, but the chunk name is prepended to the error string. */
PNG_EXPORTA(103, void, png_chunk_error, (png_const_structrp png_ptr,
png_const_charp error_message), PNG_NORETURN);
#else
/* Fatal error in PNG image of libpng - can't continue */
PNG_EXPORTA(104, void, png_err, (png_const_structrp png_ptr), PNG_NORETURN);
# define png_error(s1,s2) png_err(s1)
# define png_chunk_error(s1,s2) png_err(s1)
#endif
#ifdef PNG_WARNINGS_SUPPORTED
/* Non-fatal error in libpng. Can continue, but may have a problem. */
PNG_EXPORT(105, void, png_warning, (png_const_structrp png_ptr,
png_const_charp warning_message));
/* Non-fatal error in libpng, chunk name is prepended to message. */
PNG_EXPORT(106, void, png_chunk_warning, (png_const_structrp png_ptr,
png_const_charp warning_message));
#else
# define png_warning(s1,s2) ((void)(s1))
# define png_chunk_warning(s1,s2) ((void)(s1))
#endif
#ifdef PNG_BENIGN_ERRORS_SUPPORTED
/* Benign error in libpng. Can continue, but may have a problem.
* User can choose whether to handle as a fatal error or as a warning. */
PNG_EXPORT(107, void, png_benign_error, (png_const_structrp png_ptr,
png_const_charp warning_message));
#ifdef PNG_READ_SUPPORTED
/* Same, chunk name is prepended to message (only during read) */
PNG_EXPORT(108, void, png_chunk_benign_error, (png_const_structrp png_ptr,
png_const_charp warning_message));
#endif
PNG_EXPORT(109, void, png_set_benign_errors,
(png_structrp png_ptr, int allowed));
#else
# ifdef PNG_ALLOW_BENIGN_ERRORS
# define png_benign_error png_warning
# define png_chunk_benign_error png_chunk_warning
# else
# define png_benign_error png_error
# define png_chunk_benign_error png_chunk_error
# endif
#endif
/* The png_set_<chunk> functions are for storing values in the png_info_struct.
* Similarly, the png_get_<chunk> calls are used to read values from the
* png_info_struct, either storing the parameters in the passed variables, or
* setting pointers into the png_info_struct where the data is stored. The
* png_get_<chunk> functions return a non-zero value if the data was available
* in info_ptr, or return zero and do not change any of the parameters if the
* data was not available.
*
* These functions should be used instead of directly accessing png_info
* to avoid problems with future changes in the size and internal layout of
* png_info_struct.
*/
/* Returns "flag" if chunk data is valid in info_ptr. */
PNG_EXPORT(110, png_uint_32, png_get_valid, (png_const_structrp png_ptr,
png_const_inforp info_ptr, png_uint_32 flag));
/* Returns number of bytes needed to hold a transformed row. */
PNG_EXPORT(111, png_size_t, png_get_rowbytes, (png_const_structrp png_ptr,
png_const_inforp info_ptr));
#ifdef PNG_INFO_IMAGE_SUPPORTED
/* Returns row_pointers, which is an array of pointers to scanlines that was
* returned from png_read_png().
*/
PNG_EXPORT(112, png_bytepp, png_get_rows, (png_const_structrp png_ptr,
png_const_inforp info_ptr));
/* Set row_pointers, which is an array of pointers to scanlines for use
* by png_write_png().
*/
PNG_EXPORT(113, void, png_set_rows, (png_const_structrp png_ptr,
png_inforp info_ptr, png_bytepp row_pointers));
#endif
/* Returns number of color channels in image. */
PNG_EXPORT(114, png_byte, png_get_channels, (png_const_structrp png_ptr,
png_const_inforp info_ptr));
#ifdef PNG_EASY_ACCESS_SUPPORTED
/* Returns image width in pixels. */
PNG_EXPORT(115, png_uint_32, png_get_image_width, (png_const_structrp png_ptr,
png_const_inforp info_ptr));
/* Returns image height in pixels. */
PNG_EXPORT(116, png_uint_32, png_get_image_height, (png_const_structrp png_ptr,
png_const_inforp info_ptr));
/* Returns image bit_depth. */
PNG_EXPORT(117, png_byte, png_get_bit_depth, (png_const_structrp png_ptr,
png_const_inforp info_ptr));
/* Returns image color_type. */
PNG_EXPORT(118, png_byte, png_get_color_type, (png_const_structrp png_ptr,
png_const_inforp info_ptr));
/* Returns image filter_type. */
PNG_EXPORT(119, png_byte, png_get_filter_type, (png_const_structrp png_ptr,
png_const_inforp info_ptr));
/* Returns image interlace_type. */
PNG_EXPORT(120, png_byte, png_get_interlace_type, (png_const_structrp png_ptr,
png_const_inforp info_ptr));
/* Returns image compression_type. */
PNG_EXPORT(121, png_byte, png_get_compression_type, (png_const_structrp png_ptr,
png_const_inforp info_ptr));
/* Returns image resolution in pixels per meter, from pHYs chunk data. */
PNG_EXPORT(122, png_uint_32, png_get_pixels_per_meter,
(png_const_structrp png_ptr, png_const_inforp info_ptr));
PNG_EXPORT(123, png_uint_32, png_get_x_pixels_per_meter,
(png_const_structrp png_ptr, png_const_inforp info_ptr));
PNG_EXPORT(124, png_uint_32, png_get_y_pixels_per_meter,
(png_const_structrp png_ptr, png_const_inforp info_ptr));
/* Returns pixel aspect ratio, computed from pHYs chunk data. */
PNG_FP_EXPORT(125, float, png_get_pixel_aspect_ratio,
(png_const_structrp png_ptr, png_const_inforp info_ptr))
PNG_FIXED_EXPORT(210, png_fixed_point, png_get_pixel_aspect_ratio_fixed,
(png_const_structrp png_ptr, png_const_inforp info_ptr))
/* Returns image x, y offset in pixels or microns, from oFFs chunk data. */
PNG_EXPORT(126, png_int_32, png_get_x_offset_pixels,
(png_const_structrp png_ptr, png_const_inforp info_ptr));
PNG_EXPORT(127, png_int_32, png_get_y_offset_pixels,
(png_const_structrp png_ptr, png_const_inforp info_ptr));
PNG_EXPORT(128, png_int_32, png_get_x_offset_microns,
(png_const_structrp png_ptr, png_const_inforp info_ptr));
PNG_EXPORT(129, png_int_32, png_get_y_offset_microns,
(png_const_structrp png_ptr, png_const_inforp info_ptr));
#endif /* EASY_ACCESS */
#ifdef PNG_READ_SUPPORTED
/* Returns pointer to signature string read from PNG header */
PNG_EXPORT(130, png_const_bytep, png_get_signature, (png_const_structrp png_ptr,
png_const_inforp info_ptr));
#endif
#ifdef PNG_bKGD_SUPPORTED
PNG_EXPORT(131, png_uint_32, png_get_bKGD, (png_const_structrp png_ptr,
png_inforp info_ptr, png_color_16p *background));
#endif
#ifdef PNG_bKGD_SUPPORTED
PNG_EXPORT(132, void, png_set_bKGD, (png_const_structrp png_ptr,
png_inforp info_ptr, png_const_color_16p background));
#endif
#ifdef PNG_cHRM_SUPPORTED
PNG_FP_EXPORT(133, png_uint_32, png_get_cHRM, (png_const_structrp png_ptr,
png_const_inforp info_ptr, double *white_x, double *white_y, double *red_x,
double *red_y, double *green_x, double *green_y, double *blue_x,
double *blue_y))
PNG_FP_EXPORT(230, png_uint_32, png_get_cHRM_XYZ, (png_const_structrp png_ptr,
png_const_inforp info_ptr, double *red_X, double *red_Y, double *red_Z,
double *green_X, double *green_Y, double *green_Z, double *blue_X,
double *blue_Y, double *blue_Z))
PNG_FIXED_EXPORT(134, png_uint_32, png_get_cHRM_fixed,
(png_const_structrp png_ptr, png_const_inforp info_ptr,
png_fixed_point *int_white_x, png_fixed_point *int_white_y,
png_fixed_point *int_red_x, png_fixed_point *int_red_y,
png_fixed_point *int_green_x, png_fixed_point *int_green_y,
png_fixed_point *int_blue_x, png_fixed_point *int_blue_y))
PNG_FIXED_EXPORT(231, png_uint_32, png_get_cHRM_XYZ_fixed,
(png_const_structrp png_ptr, png_const_inforp info_ptr,
png_fixed_point *int_red_X, png_fixed_point *int_red_Y,
png_fixed_point *int_red_Z, png_fixed_point *int_green_X,
png_fixed_point *int_green_Y, png_fixed_point *int_green_Z,
png_fixed_point *int_blue_X, png_fixed_point *int_blue_Y,
png_fixed_point *int_blue_Z))
#endif
#ifdef PNG_cHRM_SUPPORTED
PNG_FP_EXPORT(135, void, png_set_cHRM, (png_const_structrp png_ptr,
png_inforp info_ptr,
double white_x, double white_y, double red_x, double red_y, double green_x,
double green_y, double blue_x, double blue_y))
PNG_FP_EXPORT(232, void, png_set_cHRM_XYZ, (png_const_structrp png_ptr,
png_inforp info_ptr, double red_X, double red_Y, double red_Z,
double green_X, double green_Y, double green_Z, double blue_X,
double blue_Y, double blue_Z))
PNG_FIXED_EXPORT(136, void, png_set_cHRM_fixed, (png_const_structrp png_ptr,
png_inforp info_ptr, png_fixed_point int_white_x,
png_fixed_point int_white_y, png_fixed_point int_red_x,
png_fixed_point int_red_y, png_fixed_point int_green_x,
png_fixed_point int_green_y, png_fixed_point int_blue_x,
png_fixed_point int_blue_y))
PNG_FIXED_EXPORT(233, void, png_set_cHRM_XYZ_fixed, (png_const_structrp png_ptr,
png_inforp info_ptr, png_fixed_point int_red_X, png_fixed_point int_red_Y,
png_fixed_point int_red_Z, png_fixed_point int_green_X,
png_fixed_point int_green_Y, png_fixed_point int_green_Z,
png_fixed_point int_blue_X, png_fixed_point int_blue_Y,
png_fixed_point int_blue_Z))
#endif
#ifdef PNG_gAMA_SUPPORTED
PNG_FP_EXPORT(137, png_uint_32, png_get_gAMA, (png_const_structrp png_ptr,
png_const_inforp info_ptr, double *file_gamma))
PNG_FIXED_EXPORT(138, png_uint_32, png_get_gAMA_fixed,
(png_const_structrp png_ptr, png_const_inforp info_ptr,
png_fixed_point *int_file_gamma))
#endif
#ifdef PNG_gAMA_SUPPORTED
PNG_FP_EXPORT(139, void, png_set_gAMA, (png_const_structrp png_ptr,
png_inforp info_ptr, double file_gamma))
PNG_FIXED_EXPORT(140, void, png_set_gAMA_fixed, (png_const_structrp png_ptr,
png_inforp info_ptr, png_fixed_point int_file_gamma))
#endif
#ifdef PNG_hIST_SUPPORTED
PNG_EXPORT(141, png_uint_32, png_get_hIST, (png_const_structrp png_ptr,
png_inforp info_ptr, png_uint_16p *hist));
#endif
#ifdef PNG_hIST_SUPPORTED
PNG_EXPORT(142, void, png_set_hIST, (png_const_structrp png_ptr,
png_inforp info_ptr, png_const_uint_16p hist));
#endif
PNG_EXPORT(143, png_uint_32, png_get_IHDR, (png_const_structrp png_ptr,
png_const_inforp info_ptr, png_uint_32 *width, png_uint_32 *height,
int *bit_depth, int *color_type, int *interlace_method,
int *compression_method, int *filter_method));
PNG_EXPORT(144, void, png_set_IHDR, (png_const_structrp png_ptr,
png_inforp info_ptr, png_uint_32 width, png_uint_32 height, int bit_depth,
int color_type, int interlace_method, int compression_method,
int filter_method));
#ifdef PNG_oFFs_SUPPORTED
PNG_EXPORT(145, png_uint_32, png_get_oFFs, (png_const_structrp png_ptr,
png_const_inforp info_ptr, png_int_32 *offset_x, png_int_32 *offset_y,
int *unit_type));
#endif
#ifdef PNG_oFFs_SUPPORTED
PNG_EXPORT(146, void, png_set_oFFs, (png_const_structrp png_ptr,
png_inforp info_ptr, png_int_32 offset_x, png_int_32 offset_y,
int unit_type));
#endif
#ifdef PNG_pCAL_SUPPORTED
PNG_EXPORT(147, png_uint_32, png_get_pCAL, (png_const_structrp png_ptr,
png_inforp info_ptr, png_charp *purpose, png_int_32 *X0,
png_int_32 *X1, int *type, int *nparams, png_charp *units,
png_charpp *params));
#endif
#ifdef PNG_pCAL_SUPPORTED
PNG_EXPORT(148, void, png_set_pCAL, (png_const_structrp png_ptr,
png_inforp info_ptr, png_const_charp purpose, png_int_32 X0, png_int_32 X1,
int type, int nparams, png_const_charp units, png_charpp params));
#endif
#ifdef PNG_pHYs_SUPPORTED
PNG_EXPORT(149, png_uint_32, png_get_pHYs, (png_const_structrp png_ptr,
png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y,
int *unit_type));
#endif
#ifdef PNG_pHYs_SUPPORTED
PNG_EXPORT(150, void, png_set_pHYs, (png_const_structrp png_ptr,
png_inforp info_ptr, png_uint_32 res_x, png_uint_32 res_y, int unit_type));
#endif
PNG_EXPORT(151, png_uint_32, png_get_PLTE, (png_const_structrp png_ptr,
png_inforp info_ptr, png_colorp *palette, int *num_palette));
PNG_EXPORT(152, void, png_set_PLTE, (png_structrp png_ptr,
png_inforp info_ptr, png_const_colorp palette, int num_palette));
#ifdef PNG_sBIT_SUPPORTED
PNG_EXPORT(153, png_uint_32, png_get_sBIT, (png_const_structrp png_ptr,
png_inforp info_ptr, png_color_8p *sig_bit));
#endif
#ifdef PNG_sBIT_SUPPORTED
PNG_EXPORT(154, void, png_set_sBIT, (png_const_structrp png_ptr,
png_inforp info_ptr, png_const_color_8p sig_bit));
#endif
#ifdef PNG_sRGB_SUPPORTED
PNG_EXPORT(155, png_uint_32, png_get_sRGB, (png_const_structrp png_ptr,
png_const_inforp info_ptr, int *file_srgb_intent));
#endif
#ifdef PNG_sRGB_SUPPORTED
PNG_EXPORT(156, void, png_set_sRGB, (png_const_structrp png_ptr,
png_inforp info_ptr, int srgb_intent));
PNG_EXPORT(157, void, png_set_sRGB_gAMA_and_cHRM, (png_const_structrp png_ptr,
png_inforp info_ptr, int srgb_intent));
#endif
#ifdef PNG_iCCP_SUPPORTED
PNG_EXPORT(158, png_uint_32, png_get_iCCP, (png_const_structrp png_ptr,
png_inforp info_ptr, png_charpp name, int *compression_type,
png_bytepp profile, png_uint_32 *proflen));
#endif
#ifdef PNG_iCCP_SUPPORTED
PNG_EXPORT(159, void, png_set_iCCP, (png_const_structrp png_ptr,
png_inforp info_ptr, png_const_charp name, int compression_type,
png_const_bytep profile, png_uint_32 proflen));
#endif
#ifdef PNG_sPLT_SUPPORTED
PNG_EXPORT(160, int, png_get_sPLT, (png_const_structrp png_ptr,
png_inforp info_ptr, png_sPLT_tpp entries));
#endif
#ifdef PNG_sPLT_SUPPORTED
PNG_EXPORT(161, void, png_set_sPLT, (png_const_structrp png_ptr,
png_inforp info_ptr, png_const_sPLT_tp entries, int nentries));
#endif
#ifdef PNG_TEXT_SUPPORTED
/* png_get_text also returns the number of text chunks in *num_text */
PNG_EXPORT(162, int, png_get_text, (png_const_structrp png_ptr,
png_inforp info_ptr, png_textp *text_ptr, int *num_text));
#endif
/* Note while png_set_text() will accept a structure whose text,
* language, and translated keywords are NULL pointers, the structure
* returned by png_get_text will always contain regular
* zero-terminated C strings. They might be empty strings but
* they will never be NULL pointers.
*/
#ifdef PNG_TEXT_SUPPORTED
PNG_EXPORT(163, void, png_set_text, (png_const_structrp png_ptr,
png_inforp info_ptr, png_const_textp text_ptr, int num_text));
#endif
#ifdef PNG_tIME_SUPPORTED
PNG_EXPORT(164, png_uint_32, png_get_tIME, (png_const_structrp png_ptr,
png_inforp info_ptr, png_timep *mod_time));
#endif
#ifdef PNG_tIME_SUPPORTED
PNG_EXPORT(165, void, png_set_tIME, (png_const_structrp png_ptr,
png_inforp info_ptr, png_const_timep mod_time));
#endif
#ifdef PNG_tRNS_SUPPORTED
PNG_EXPORT(166, png_uint_32, png_get_tRNS, (png_const_structrp png_ptr,
png_inforp info_ptr, png_bytep *trans_alpha, int *num_trans,
png_color_16p *trans_color));
#endif
#ifdef PNG_tRNS_SUPPORTED
PNG_EXPORT(167, void, png_set_tRNS, (png_structrp png_ptr,
png_inforp info_ptr, png_const_bytep trans_alpha, int num_trans,
png_const_color_16p trans_color));
#endif
#ifdef PNG_sCAL_SUPPORTED
PNG_FP_EXPORT(168, png_uint_32, png_get_sCAL, (png_const_structrp png_ptr,
png_const_inforp info_ptr, int *unit, double *width, double *height))
#if defined(PNG_FLOATING_ARITHMETIC_SUPPORTED) || \
defined(PNG_FLOATING_POINT_SUPPORTED)
/* NOTE: this API is currently implemented using floating point arithmetic,
* consequently it can only be used on systems with floating point support.
* In any case the range of values supported by png_fixed_point is small and it
* is highly recommended that png_get_sCAL_s be used instead.
*/
PNG_FIXED_EXPORT(214, png_uint_32, png_get_sCAL_fixed,
(png_const_structrp png_ptr, png_const_inforp info_ptr, int *unit,
png_fixed_point *width, png_fixed_point *height))
#endif
PNG_EXPORT(169, png_uint_32, png_get_sCAL_s,
(png_const_structrp png_ptr, png_const_inforp info_ptr, int *unit,
png_charpp swidth, png_charpp sheight));
PNG_FP_EXPORT(170, void, png_set_sCAL, (png_const_structrp png_ptr,
png_inforp info_ptr, int unit, double width, double height))
PNG_FIXED_EXPORT(213, void, png_set_sCAL_fixed, (png_const_structrp png_ptr,
png_inforp info_ptr, int unit, png_fixed_point width,
png_fixed_point height))
PNG_EXPORT(171, void, png_set_sCAL_s, (png_const_structrp png_ptr,
png_inforp info_ptr, int unit,
png_const_charp swidth, png_const_charp sheight));
#endif /* sCAL */
#ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
/* Provide the default handling for all unknown chunks or, optionally, for
* specific unknown chunks.
*
* NOTE: prior to 1.6.0 the handling specified for particular chunks on read was
* ignored and the default was used, the per-chunk setting only had an effect on
* write. If you wish to have chunk-specific handling on read in code that must
* work on earlier versions you must use a user chunk callback to specify the
* desired handling (keep or discard.)
*
* The 'keep' parameter is a PNG_HANDLE_CHUNK_ value as listed below. The
* parameter is interpreted as follows:
*
* READ:
* PNG_HANDLE_CHUNK_AS_DEFAULT:
* Known chunks: do normal libpng processing, do not keep the chunk (but
* see the comments below about PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
* Unknown chunks: for a specific chunk use the global default, when used
* as the default discard the chunk data.
* PNG_HANDLE_CHUNK_NEVER:
* Discard the chunk data.
* PNG_HANDLE_CHUNK_IF_SAFE:
* Keep the chunk data if the chunk is not critical else raise a chunk
* error.
* PNG_HANDLE_CHUNK_ALWAYS:
* Keep the chunk data.
*
* If the chunk data is saved it can be retrieved using png_get_unknown_chunks,
* below. Notice that specifying "AS_DEFAULT" as a global default is equivalent
* to specifying "NEVER", however when "AS_DEFAULT" is used for specific chunks
* it simply resets the behavior to the libpng default.
*
* INTERACTION WTIH USER CHUNK CALLBACKS:
* The per-chunk handling is always used when there is a png_user_chunk_ptr
* callback and the callback returns 0; the chunk is then always stored *unless*
* it is critical and the per-chunk setting is other than ALWAYS. Notice that
* the global default is *not* used in this case. (In effect the per-chunk
* value is incremented to at least IF_SAFE.)
*
* IMPORTANT NOTE: this behavior will change in libpng 1.7 - the global and
* per-chunk defaults will be honored. If you want to preserve the current
* behavior when your callback returns 0 you must set PNG_HANDLE_CHUNK_IF_SAFE
* as the default - if you don't do this libpng 1.6 will issue a warning.
*
* If you want unhandled unknown chunks to be discarded in libpng 1.6 and
* earlier simply return '1' (handled).
*
* PNG_HANDLE_AS_UNKNOWN_SUPPORTED:
* If this is *not* set known chunks will always be handled by libpng and
* will never be stored in the unknown chunk list. Known chunks listed to
* png_set_keep_unknown_chunks will have no effect. If it is set then known
* chunks listed with a keep other than AS_DEFAULT will *never* be processed
* by libpng, in addition critical chunks must either be processed by the
* callback or saved.
*
* The IHDR and IEND chunks must not be listed. Because this turns off the
* default handling for chunks that would otherwise be recognized the
* behavior of libpng transformations may well become incorrect!
*
* WRITE:
* When writing chunks the options only apply to the chunks specified by
* png_set_unknown_chunks (below), libpng will *always* write known chunks
* required by png_set_ calls and will always write the core critical chunks
* (as required for PLTE).
*
* Each chunk in the png_set_unknown_chunks list is looked up in the
* png_set_keep_unknown_chunks list to find the keep setting, this is then
* interpreted as follows:
*
* PNG_HANDLE_CHUNK_AS_DEFAULT:
* Write safe-to-copy chunks and write other chunks if the global
* default is set to _ALWAYS, otherwise don't write this chunk.
* PNG_HANDLE_CHUNK_NEVER:
* Do not write the chunk.
* PNG_HANDLE_CHUNK_IF_SAFE:
* Write the chunk if it is safe-to-copy, otherwise do not write it.
* PNG_HANDLE_CHUNK_ALWAYS:
src/Source/LibPNG/png.h view on Meta::CPAN
* num_chunks:
* ===========
* If num_chunks is positive, then the "keep" parameter specifies the manner
* for handling only those chunks appearing in the chunk_list array,
* otherwise the chunk list array is ignored.
*
* If num_chunks is 0 the "keep" parameter specifies the default behavior for
* unknown chunks, as described above.
*
* If num_chunks is negative, then the "keep" parameter specifies the manner
* for handling all unknown chunks plus all chunks recognized by libpng
* except for the IHDR, PLTE, tRNS, IDAT, and IEND chunks (which continue to
* be processed by libpng.
*/
PNG_EXPORT(172, void, png_set_keep_unknown_chunks, (png_structrp png_ptr,
int keep, png_const_bytep chunk_list, int num_chunks));
/* The "keep" PNG_HANDLE_CHUNK_ parameter for the specified chunk is returned;
* the result is therefore true (non-zero) if special handling is required,
* false for the default handling.
*/
PNG_EXPORT(173, int, png_handle_as_unknown, (png_const_structrp png_ptr,
png_const_bytep chunk_name));
#endif
#ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
PNG_EXPORT(174, void, png_set_unknown_chunks, (png_const_structrp png_ptr,
png_inforp info_ptr, png_const_unknown_chunkp unknowns,
int num_unknowns));
/* NOTE: prior to 1.6.0 this routine set the 'location' field of the added
* unknowns to the location currently stored in the png_struct. This is
* invariably the wrong value on write. To fix this call the following API
* for each chunk in the list with the correct location. If you know your
* code won't be compiled on earlier versions you can rely on
* png_set_unknown_chunks(write-ptr, png_get_unknown_chunks(read-ptr)) doing
* the correct thing.
*/
PNG_EXPORT(175, void, png_set_unknown_chunk_location,
(png_const_structrp png_ptr, png_inforp info_ptr, int chunk, int location));
PNG_EXPORT(176, int, png_get_unknown_chunks, (png_const_structrp png_ptr,
png_inforp info_ptr, png_unknown_chunkpp entries));
#endif
/* Png_free_data() will turn off the "valid" flag for anything it frees.
* If you need to turn it off for a chunk that your application has freed,
* you can use png_set_invalid(png_ptr, info_ptr, PNG_INFO_CHNK);
*/
PNG_EXPORT(177, void, png_set_invalid, (png_const_structrp png_ptr,
png_inforp info_ptr, int mask));
#ifdef PNG_INFO_IMAGE_SUPPORTED
/* The "params" pointer is currently not used and is for future expansion. */
#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
PNG_EXPORT(178, void, png_read_png, (png_structrp png_ptr, png_inforp info_ptr,
int transforms, png_voidp params));
#endif
#ifdef PNG_WRITE_SUPPORTED
PNG_EXPORT(179, void, png_write_png, (png_structrp png_ptr, png_inforp info_ptr,
int transforms, png_voidp params));
#endif
#endif
PNG_EXPORT(180, png_const_charp, png_get_copyright,
(png_const_structrp png_ptr));
PNG_EXPORT(181, png_const_charp, png_get_header_ver,
(png_const_structrp png_ptr));
PNG_EXPORT(182, png_const_charp, png_get_header_version,
(png_const_structrp png_ptr));
PNG_EXPORT(183, png_const_charp, png_get_libpng_ver,
(png_const_structrp png_ptr));
#ifdef PNG_MNG_FEATURES_SUPPORTED
PNG_EXPORT(184, png_uint_32, png_permit_mng_features, (png_structrp png_ptr,
png_uint_32 mng_features_permitted));
#endif
/* For use in png_set_keep_unknown, added to version 1.2.6 */
#define PNG_HANDLE_CHUNK_AS_DEFAULT 0
#define PNG_HANDLE_CHUNK_NEVER 1
#define PNG_HANDLE_CHUNK_IF_SAFE 2
#define PNG_HANDLE_CHUNK_ALWAYS 3
#define PNG_HANDLE_CHUNK_LAST 4
/* Strip the prepended error numbers ("#nnn ") from error and warning
* messages before passing them to the error or warning handler.
*/
#ifdef PNG_ERROR_NUMBERS_SUPPORTED
PNG_EXPORT(185, void, png_set_strip_error_numbers, (png_structrp png_ptr,
png_uint_32 strip_mode));
#endif
/* Added in libpng-1.2.6 */
#ifdef PNG_SET_USER_LIMITS_SUPPORTED
PNG_EXPORT(186, void, png_set_user_limits, (png_structrp png_ptr,
png_uint_32 user_width_max, png_uint_32 user_height_max));
PNG_EXPORT(187, png_uint_32, png_get_user_width_max,
(png_const_structrp png_ptr));
PNG_EXPORT(188, png_uint_32, png_get_user_height_max,
(png_const_structrp png_ptr));
/* Added in libpng-1.4.0 */
PNG_EXPORT(189, void, png_set_chunk_cache_max, (png_structrp png_ptr,
png_uint_32 user_chunk_cache_max));
PNG_EXPORT(190, png_uint_32, png_get_chunk_cache_max,
(png_const_structrp png_ptr));
/* Added in libpng-1.4.1 */
PNG_EXPORT(191, void, png_set_chunk_malloc_max, (png_structrp png_ptr,
png_alloc_size_t user_chunk_cache_max));
PNG_EXPORT(192, png_alloc_size_t, png_get_chunk_malloc_max,
(png_const_structrp png_ptr));
#endif
#if defined(PNG_INCH_CONVERSIONS_SUPPORTED)
PNG_EXPORT(193, png_uint_32, png_get_pixels_per_inch,
(png_const_structrp png_ptr, png_const_inforp info_ptr));
PNG_EXPORT(194, png_uint_32, png_get_x_pixels_per_inch,
(png_const_structrp png_ptr, png_const_inforp info_ptr));
PNG_EXPORT(195, png_uint_32, png_get_y_pixels_per_inch,
(png_const_structrp png_ptr, png_const_inforp info_ptr));
PNG_FP_EXPORT(196, float, png_get_x_offset_inches,
(png_const_structrp png_ptr, png_const_inforp info_ptr))
#ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
PNG_FIXED_EXPORT(211, png_fixed_point, png_get_x_offset_inches_fixed,
(png_const_structrp png_ptr, png_const_inforp info_ptr))
#endif
PNG_FP_EXPORT(197, float, png_get_y_offset_inches, (png_const_structrp png_ptr,
png_const_inforp info_ptr))
#ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
PNG_FIXED_EXPORT(212, png_fixed_point, png_get_y_offset_inches_fixed,
(png_const_structrp png_ptr, png_const_inforp info_ptr))
#endif
# ifdef PNG_pHYs_SUPPORTED
PNG_EXPORT(198, png_uint_32, png_get_pHYs_dpi, (png_const_structrp png_ptr,
png_const_inforp info_ptr, png_uint_32 *res_x, png_uint_32 *res_y,
int *unit_type));
# endif /* pHYs */
#endif /* INCH_CONVERSIONS */
/* Added in libpng-1.4.0 */
#ifdef PNG_IO_STATE_SUPPORTED
PNG_EXPORT(199, png_uint_32, png_get_io_state, (png_const_structrp png_ptr));
/* Removed from libpng 1.6; use png_get_io_chunk_type. */
PNG_REMOVED(200, png_const_bytep, png_get_io_chunk_name, (png_structrp png_ptr),
PNG_DEPRECATED)
PNG_EXPORT(216, png_uint_32, png_get_io_chunk_type,
(png_const_structrp png_ptr));
/* The flags returned by png_get_io_state() are the following: */
# define PNG_IO_NONE 0x0000 /* no I/O at this moment */
# define PNG_IO_READING 0x0001 /* currently reading */
# define PNG_IO_WRITING 0x0002 /* currently writing */
# define PNG_IO_SIGNATURE 0x0010 /* currently at the file signature */
# define PNG_IO_CHUNK_HDR 0x0020 /* currently at the chunk header */
# define PNG_IO_CHUNK_DATA 0x0040 /* currently at the chunk data */
# define PNG_IO_CHUNK_CRC 0x0080 /* currently at the chunk crc */
# define PNG_IO_MASK_OP 0x000f /* current operation: reading/writing */
# define PNG_IO_MASK_LOC 0x00f0 /* current location: sig/hdr/data/crc */
#endif /* IO_STATE */
/* Interlace support. The following macros are always defined so that if
* libpng interlace handling is turned off the macros may be used to handle
* interlaced images within the application.
*/
#define PNG_INTERLACE_ADAM7_PASSES 7
/* Two macros to return the first row and first column of the original,
* full, image which appears in a given pass. 'pass' is in the range 0
* to 6 and the result is in the range 0 to 7.
*/
#define PNG_PASS_START_ROW(pass) (((1&~(pass))<<(3-((pass)>>1)))&7)
#define PNG_PASS_START_COL(pass) (((1& (pass))<<(3-(((pass)+1)>>1)))&7)
src/Source/LibPNG/png.h view on Meta::CPAN
*
* Note that the rounding factors are NOT supposed to be the same! 128 and
* 32768 are correct for the NODIV code; 127 and 32767 are correct for the
* standard method.
*
* [Optimized code by Greg Roelofs and Mark Adler...blame us for bugs. :-) ]
*/
/* fg and bg should be in `gamma 1.0' space; alpha is the opacity */
# define png_composite(composite, fg, alpha, bg) \
{ png_uint_16 temp = (png_uint_16)((png_uint_16)(fg) \
* (png_uint_16)(alpha) \
+ (png_uint_16)(bg)*(png_uint_16)(255 \
- (png_uint_16)(alpha)) + 128); \
(composite) = (png_byte)((temp + (temp >> 8)) >> 8); }
# define png_composite_16(composite, fg, alpha, bg) \
{ png_uint_32 temp = (png_uint_32)((png_uint_32)(fg) \
* (png_uint_32)(alpha) \
+ (png_uint_32)(bg)*(65535 \
- (png_uint_32)(alpha)) + 32768); \
(composite) = (png_uint_16)((temp + (temp >> 16)) >> 16); }
#else /* Standard method using integer division */
# define png_composite(composite, fg, alpha, bg) \
(composite) = (png_byte)(((png_uint_16)(fg) * (png_uint_16)(alpha) + \
(png_uint_16)(bg) * (png_uint_16)(255 - (png_uint_16)(alpha)) + \
127) / 255)
# define png_composite_16(composite, fg, alpha, bg) \
(composite) = (png_uint_16)(((png_uint_32)(fg) * (png_uint_32)(alpha) + \
(png_uint_32)(bg)*(png_uint_32)(65535 - (png_uint_32)(alpha)) + \
32767) / 65535)
#endif /* READ_COMPOSITE_NODIV */
#ifdef PNG_READ_INT_FUNCTIONS_SUPPORTED
PNG_EXPORT(201, png_uint_32, png_get_uint_32, (png_const_bytep buf));
PNG_EXPORT(202, png_uint_16, png_get_uint_16, (png_const_bytep buf));
PNG_EXPORT(203, png_int_32, png_get_int_32, (png_const_bytep buf));
#endif
PNG_EXPORT(204, png_uint_32, png_get_uint_31, (png_const_structrp png_ptr,
png_const_bytep buf));
/* No png_get_int_16 -- may be added if there's a real need for it. */
/* Place a 32-bit number into a buffer in PNG byte order (big-endian). */
#ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
PNG_EXPORT(205, void, png_save_uint_32, (png_bytep buf, png_uint_32 i));
#endif
#ifdef PNG_SAVE_INT_32_SUPPORTED
PNG_EXPORT(206, void, png_save_int_32, (png_bytep buf, png_int_32 i));
#endif
/* Place a 16-bit number into a buffer in PNG byte order.
* The parameter is declared unsigned int, not png_uint_16,
* just to avoid potential problems on pre-ANSI C compilers.
*/
#ifdef PNG_WRITE_INT_FUNCTIONS_SUPPORTED
PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i));
/* No png_save_int_16 -- may be added if there's a real need for it. */
#endif
#ifdef PNG_USE_READ_MACROS
/* Inline macros to do direct reads of bytes from the input buffer.
* The png_get_int_32() routine assumes we are using two's complement
* format for negative values, which is almost certainly true.
*/
# define PNG_get_uint_32(buf) \
(((png_uint_32)(*(buf)) << 24) + \
((png_uint_32)(*((buf) + 1)) << 16) + \
((png_uint_32)(*((buf) + 2)) << 8) + \
((png_uint_32)(*((buf) + 3))))
/* From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
* function) incorrectly returned a value of type png_uint_32.
*/
# define PNG_get_uint_16(buf) \
((png_uint_16) \
(((unsigned int)(*(buf)) << 8) + \
((unsigned int)(*((buf) + 1)))))
# define PNG_get_int_32(buf) \
((png_int_32)((*(buf) & 0x80) \
? -((png_int_32)((png_get_uint_32(buf) ^ 0xffffffffL) + 1)) \
: (png_int_32)png_get_uint_32(buf)))
/* If PNG_PREFIX is defined the same thing as below happens in pnglibconf.h,
* but defining a macro name prefixed with PNG_PREFIX.
*/
# ifndef PNG_PREFIX
# define png_get_uint_32(buf) PNG_get_uint_32(buf)
# define png_get_uint_16(buf) PNG_get_uint_16(buf)
# define png_get_int_32(buf) PNG_get_int_32(buf)
# endif
#else
# ifdef PNG_PREFIX
/* No macros; revert to the (redefined) function */
# define PNG_get_uint_32 (png_get_uint_32)
# define PNG_get_uint_16 (png_get_uint_16)
# define PNG_get_int_32 (png_get_int_32)
# endif
#endif
#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) || \
defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
/*******************************************************************************
* SIMPLIFIED API
*******************************************************************************
*
* Please read the documentation in libpng-manual.txt (TODO: write said
* documentation) if you don't understand what follows.
*
* The simplified API hides the details of both libpng and the PNG file format
* itself. It allows PNG files to be read into a very limited number of
* in-memory bitmap formats or to be written from the same formats. If these
* formats do not accomodate your needs then you can, and should, use the more
* sophisticated APIs above - these support a wide variety of in-memory formats
* and a wide variety of sophisticated transformations to those formats as well
* as a wide variety of APIs to manipulate ancillary information.
*
* To read a PNG file using the simplified API:
*
* 1) Declare a 'png_image' structure (see below) on the stack and set the
* version field to PNG_IMAGE_VERSION.
* 2) Call the appropriate png_image_begin_read... function.
* 3) Set the png_image 'format' member to the required sample format.
* 4) Allocate a buffer for the image and, if required, the color-map.
* 5) Call png_image_finish_read to read the image and, if required, the
* color-map into your buffers.
*
* There are no restrictions on the format of the PNG input itself; all valid
* color types, bit depths, and interlace methods are acceptable, and the
* input image is transformed as necessary to the requested in-memory format
* during the png_image_finish_read() step. The only caveat is that if you
* request a color-mapped image from a PNG that is full-color or makes
* complex use of an alpha channel the transformation is extremely lossy and the
* result may look terrible.
*
* To write a PNG file using the simplified API:
*
* 1) Declare a 'png_image' structure on the stack and memset() it to all zero.
* 2) Initialize the members of the structure that describe the image, setting
* the 'format' member to the format of the image samples.
* 3) Call the appropriate png_image_write... function with a pointer to the
* image and, if necessary, the color-map to write the PNG data.
*
* png_image is a structure that describes the in-memory format of an image
* when it is being read or defines the in-memory format of an image that you
* need to write:
*/
#define PNG_IMAGE_VERSION 1
typedef struct png_control *png_controlp;
typedef struct
{
png_controlp opaque; /* Initialize to NULL, free with png_image_free */
png_uint_32 version; /* Set to PNG_IMAGE_VERSION */
png_uint_32 width; /* Image width in pixels (columns) */
png_uint_32 height; /* Image height in pixels (rows) */
png_uint_32 format; /* Image format as defined below */
png_uint_32 flags; /* A bit mask containing informational flags */
png_uint_32 colormap_entries;
/* Number of entries in the color-map */
/* In the event of an error or warning the following field will be set to a
* non-zero value and the 'message' field will contain a '\0' terminated
* string with the libpng error or warning message. If both warnings and
* an error were encountered, only the error is recorded. If there
* are multiple warnings, only the first one is recorded.
*
* The upper 30 bits of this value are reserved, the low two bits contain
* a value as follows:
*/
# define PNG_IMAGE_WARNING 1
# define PNG_IMAGE_ERROR 2
/*
* The result is a two-bit code such that a value more than 1 indicates
* a failure in the API just called:
*
* 0 - no warning or error
* 1 - warning
* 2 - error
* 3 - error preceded by warning
*/
# define PNG_IMAGE_FAILED(png_cntrl) ((((png_cntrl).warning_or_error)&0x03)>1)
png_uint_32 warning_or_error;
char message[64];
} png_image, *png_imagep;
/* The samples of the image have one to four channels whose components have
* original values in the range 0 to 1.0:
*
* 1: A single gray or luminance channel (G).
* 2: A gray/luminance channel and an alpha channel (GA).
* 3: Three red, green, blue color channels (RGB).
* 4: Three color channels and an alpha channel (RGBA).
*
* The components are encoded in one of two ways:
src/Source/LibPNG/png.h view on Meta::CPAN
*
* b) As a value in the range 0..65535, contained in a 2-byte integer. All
* channels can be converted to the original value by dividing by 65535; all
* channels are linear. Color channels use the RGB encoding (RGB end-points) of
* the sRGB specification. This encoding is identified by the
* PNG_FORMAT_FLAG_LINEAR flag below.
*
* When the simplified API needs to convert between sRGB and linear colorspaces,
* the actual sRGB transfer curve defined in the sRGB specification (see the
* article at http://en.wikipedia.org/wiki/SRGB) is used, not the gamma=1/2.2
* approximation used elsewhere in libpng.
*
* When an alpha channel is present it is expected to denote pixel coverage
* of the color or luminance channels and is returned as an associated alpha
* channel: the color/gray channels are scaled (pre-multiplied) by the alpha
* value.
*
* The samples are either contained directly in the image data, between 1 and 8
* bytes per pixel according to the encoding, or are held in a color-map indexed
* by bytes in the image data. In the case of a color-map the color-map entries
* are individual samples, encoded as above, and the image data has one byte per
* pixel to select the relevant sample from the color-map.
*/
/* PNG_FORMAT_*
*
* #defines to be used in png_image::format. Each #define identifies a
* particular layout of sample data and, if present, alpha values. There are
* separate defines for each of the two component encodings.
*
* A format is built up using single bit flag values. All combinations are
* valid. Formats can be built up from the flag values or you can use one of
* the predefined values below. When testing formats always use the FORMAT_FLAG
* macros to test for individual features - future versions of the library may
* add new flags.
*
* When reading or writing color-mapped images the format should be set to the
* format of the entries in the color-map then png_image_{read,write}_colormap
* called to read or write the color-map and set the format correctly for the
* image data. Do not set the PNG_FORMAT_FLAG_COLORMAP bit directly!
*
* NOTE: libpng can be built with particular features disabled, if you see
* compiler errors because the definition of one of the following flags has been
* compiled out it is because libpng does not have the required support. It is
* possible, however, for the libpng configuration to enable the format on just
* read or just write; in that case you may see an error at run time. You can
* guard against this by checking for the definition of the appropriate
* "_SUPPORTED" macro, one of:
*
* PNG_SIMPLIFIED_{READ,WRITE}_{BGR,AFIRST}_SUPPORTED
*/
#define PNG_FORMAT_FLAG_ALPHA 0x01U /* format with an alpha channel */
#define PNG_FORMAT_FLAG_COLOR 0x02U /* color format: otherwise grayscale */
#define PNG_FORMAT_FLAG_LINEAR 0x04U /* 2 byte channels else 1 byte */
#define PNG_FORMAT_FLAG_COLORMAP 0x08U /* image data is color-mapped */
src/Source/LibPNG/png.h view on Meta::CPAN
*/
#define PNG_FORMAT_RGB_COLORMAP (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_COLORMAP)
#define PNG_FORMAT_BGR_COLORMAP (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_COLORMAP)
#define PNG_FORMAT_RGBA_COLORMAP (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_COLORMAP)
#define PNG_FORMAT_ARGB_COLORMAP (PNG_FORMAT_ARGB|PNG_FORMAT_FLAG_COLORMAP)
#define PNG_FORMAT_BGRA_COLORMAP (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_COLORMAP)
#define PNG_FORMAT_ABGR_COLORMAP (PNG_FORMAT_ABGR|PNG_FORMAT_FLAG_COLORMAP)
/* PNG_IMAGE macros
*
* These are convenience macros to derive information from a png_image
* structure. The PNG_IMAGE_SAMPLE_ macros return values appropriate to the
* actual image sample values - either the entries in the color-map or the
* pixels in the image. The PNG_IMAGE_PIXEL_ macros return corresponding values
* for the pixels and will always return 1 for color-mapped formats. The
* remaining macros return information about the rows in the image and the
* complete image.
*
* NOTE: All the macros that take a png_image::format parameter are compile time
* constants if the format parameter is, itself, a constant. Therefore these
* macros can be used in array declarations and case labels where required.
* Similarly the macros are also pre-processor constants (sizeof is not used) so
* they can be used in #if tests.
*
* First the information about the samples.
*/
#define PNG_IMAGE_SAMPLE_CHANNELS(fmt)\
(((fmt)&(PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA))+1)
/* Return the total number of channels in a given format: 1..4 */
src/Source/LibPNG/png.h view on Meta::CPAN
* color-mapped it is the size of one color-map entry (and image pixels are
* one byte in size), otherwise it is the size of one image pixel.
*/
#define PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(fmt)\
(PNG_IMAGE_SAMPLE_CHANNELS(fmt) * 256)
/* The maximum size of the color-map required by the format expressed in a
* count of components. This can be used to compile-time allocate a
* color-map:
*
* png_uint_16 colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(linear_fmt)];
*
* png_byte colormap[PNG_IMAGE_MAXIMUM_COLORMAP_COMPONENTS(sRGB_fmt)];
*
* Alternatively use the PNG_IMAGE_COLORMAP_SIZE macro below to use the
* information from one of the png_image_begin_read_ APIs and dynamically
* allocate the required memory.
*/
/* Corresponding information about the pixels */
#define PNG_IMAGE_PIXEL_(test,fmt)\
(((fmt)&PNG_FORMAT_FLAG_COLORMAP)?1:test(fmt))
#define PNG_IMAGE_PIXEL_CHANNELS(fmt)\
PNG_IMAGE_PIXEL_(PNG_IMAGE_SAMPLE_CHANNELS,fmt)
/* The number of separate channels (components) in a pixel; 1 for a
src/Source/LibPNG/png.h view on Meta::CPAN
#define PNG_IMAGE_ROW_STRIDE(image)\
(PNG_IMAGE_PIXEL_CHANNELS((image).format) * (image).width)
/* Return the total number of components in a single row of the image; this
* is the minimum 'row stride', the minimum count of components between each
* row. For a color-mapped image this is the minimum number of bytes in a
* row.
*/
#define PNG_IMAGE_BUFFER_SIZE(image, row_stride)\
(PNG_IMAGE_PIXEL_COMPONENT_SIZE((image).format)*(image).height*(row_stride))
/* Return the size, in bytes, of an image buffer given a png_image and a row
* stride - the number of components to leave space for in each row.
*/
#define PNG_IMAGE_SIZE(image)\
PNG_IMAGE_BUFFER_SIZE(image, PNG_IMAGE_ROW_STRIDE(image))
/* Return the size, in bytes, of the image in memory given just a png_image;
* the row stride is the minimum stride required for the image.
*/
#define PNG_IMAGE_COLORMAP_SIZE(image)\
(PNG_IMAGE_SAMPLE_SIZE((image).format) * (image).colormap_entries)
/* Return the size, in bytes, of the color-map of this image. If the image
* format is not a color-map format this will return a size sufficient for
* 256 entries in the given format; check PNG_FORMAT_FLAG_COLORMAP if
* you don't want to allocate a color-map in this case.
*/
/* PNG_IMAGE_FLAG_*
*
* Flags containing additional information about the image are held in the
* 'flags' field of png_image.
*/
#define PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB 0x01
/* This indicates the the RGB values of the in-memory bitmap do not
* correspond to the red, green and blue end-points defined by sRGB.
*/
#define PNG_IMAGE_FLAG_FAST 0x02
/* On write emphasise speed over compression; the resultant PNG file will be
* larger but will be produced significantly faster, particular for large
* images. Do not use this option for images which will be distributed, only
src/Source/LibPNG/png.h view on Meta::CPAN
* this flag only affects the interpretation of 16-bit images from an
* external source. It is recommended that the application expose this flag
* to the user; the user can normally easily recognize the difference between
* linear and sRGB encoding. This flag has no effect on write - the data
* passed to the write APIs must have the correct encoding (as defined
* above.)
*
* If the flag is not set (the default) input 16-bit per component data is
* assumed to be linear.
*
* NOTE: the flag can only be set after the png_image_begin_read_ call,
* because that call initializes the 'flags' field.
*/
#ifdef PNG_SIMPLIFIED_READ_SUPPORTED
/* READ APIs
* ---------
*
* The png_image passed to the read APIs must have been initialized by setting
* the png_controlp field 'opaque' to NULL (or, safer, memset the whole thing.)
*/
#ifdef PNG_STDIO_SUPPORTED
PNG_EXPORT(234, int, png_image_begin_read_from_file, (png_imagep image,
const char *file_name));
/* The named file is opened for read and the image header is filled in
* from the PNG header in the file.
*/
PNG_EXPORT(235, int, png_image_begin_read_from_stdio, (png_imagep image,
FILE* file));
/* The PNG header is read from the stdio FILE object. */
#endif /* STDIO */
PNG_EXPORT(236, int, png_image_begin_read_from_memory, (png_imagep image,
png_const_voidp memory, png_size_t size));
/* The PNG header is read from the given memory buffer. */
PNG_EXPORT(237, int, png_image_finish_read, (png_imagep image,
png_const_colorp background, void *buffer, png_int_32 row_stride,
void *colormap));
/* Finish reading the image into the supplied buffer and clean up the
* png_image structure.
*
* row_stride is the step, in byte or 2-byte units as appropriate,
* between adjacent rows. A positive stride indicates that the top-most row
* is first in the buffer - the normal top-down arrangement. A negative
* stride indicates that the bottom-most row is first in the buffer.
*
* background need only be supplied if an alpha channel must be removed from
* a png_byte format and the removal is to be done by compositing on a solid
* color; otherwise it may be NULL and any composition will be done directly
* onto the buffer. The value is an sRGB color to use for the background,
* for grayscale output the green channel is used.
*
* background must be supplied when an alpha channel must be removed from a
* single byte color-mapped output format, in other words if:
*
* 1) The original format from png_image_begin_read_from_* had
* PNG_FORMAT_FLAG_ALPHA set.
* 2) The format set by the application does not.
* 3) The format set by the application has PNG_FORMAT_FLAG_COLORMAP set and
* PNG_FORMAT_FLAG_LINEAR *not* set.
*
* For linear output removing the alpha channel is always done by compositing
* on black and background is ignored.
*
* colormap must be supplied when PNG_FORMAT_FLAG_COLORMAP is set. It must
* be at least the size (in bytes) returned by PNG_IMAGE_COLORMAP_SIZE.
* image->colormap_entries will be updated to the actual number of entries
* written to the colormap; this may be less than the original value.
*/
PNG_EXPORT(238, void, png_image_free, (png_imagep image));
/* Free any data allocated by libpng in image->opaque, setting the pointer to
* NULL. May be called at any time after the structure is initialized.
*/
#endif /* SIMPLIFIED_READ */
#ifdef PNG_SIMPLIFIED_WRITE_SUPPORTED
#ifdef PNG_STDIO_SUPPORTED
/* WRITE APIS
* ----------
* For write you must initialize a png_image structure to describe the image to
* be written. To do this use memset to set the whole structure to 0 then
* initialize fields describing your image.
*
* version: must be set to PNG_IMAGE_VERSION
* opaque: must be initialized to NULL
* width: image width in pixels
* height: image height in rows
* format: the format of the data (image and color-map) you wish to write
* flags: set to 0 unless one of the defined flags applies; set
* PNG_IMAGE_FLAG_COLORSPACE_NOT_sRGB for color format images where the RGB
* values do not correspond to the colors in sRGB.
* colormap_entries: set to the number of entries in the color-map (0 to 256)
*/
PNG_EXPORT(239, int, png_image_write_to_file, (png_imagep image,
const char *file, int convert_to_8bit, const void *buffer,
png_int_32 row_stride, const void *colormap));
/* Write the image to the named file. */
PNG_EXPORT(240, int, png_image_write_to_stdio, (png_imagep image, FILE *file,
int convert_to_8_bit, const void *buffer, png_int_32 row_stride,
const void *colormap));
/* Write the image to the given (FILE*). */
/* With both write APIs if image is in one of the linear formats with 16-bit
* data then setting convert_to_8_bit will cause the output to be an 8-bit PNG
* gamma encoded according to the sRGB specification, otherwise a 16-bit linear
* encoded PNG file is written.
*
* With color-mapped data formats the colormap parameter point to a color-map
* with at least image->colormap_entries encoded in the specified format. If
src/Source/LibPNG/png.h view on Meta::CPAN
* Note that the write API does not support interlacing or sub-8-bit pixels.
*/
#endif /* STDIO */
#endif /* SIMPLIFIED_WRITE */
/*******************************************************************************
* END OF SIMPLIFIED API
******************************************************************************/
#endif /* SIMPLIFIED_{READ|WRITE} */
#ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
PNG_EXPORT(242, void, png_set_check_for_invalid_index,
(png_structrp png_ptr, int allowed));
# ifdef PNG_GET_PALETTE_MAX_SUPPORTED
PNG_EXPORT(243, int, png_get_palette_max, (png_const_structp png_ptr,
png_const_infop info_ptr));
# endif
#endif /* CHECK_FOR_INVALID_INDEX */
/*******************************************************************************
* IMPLEMENTATION OPTIONS
*******************************************************************************
*
* Support for arbitrary implementation-specific optimizations. The API allows
* particular options to be turned on or off. 'Option' is the number of the
* option and 'onoff' is 0 (off) or non-0 (on). The value returned is given
* by the PNG_OPTION_ defines below.
*
* HARDWARE: normally hardware capabilites, such as the Intel SSE instructions,
* are detected at run time, however sometimes it may be impossible
* to do this in user mode, in which case it is necessary to discover
* the capabilities in an OS specific way. Such capabilities are
* listed here when libpng has support for them and must be turned
* ON by the application if present.
*
* SOFTWARE: sometimes software optimizations actually result in performance
* decrease on some architectures or systems, or with some sets of
* PNG images. 'Software' options allow such optimizations to be
* selected at run time.
*/
#ifdef PNG_SET_OPTION_SUPPORTED
#ifdef PNG_ARM_NEON_API_SUPPORTED
# define PNG_ARM_NEON 0 /* HARDWARE: ARM Neon SIMD instructions supported */
src/Source/LibPNG/png.h view on Meta::CPAN
#define PNG_MAXIMUM_INFLATE_WINDOW 2 /* SOFTWARE: force maximum window */
#define PNG_SKIP_sRGB_CHECK_PROFILE 4 /* SOFTWARE: Check ICC profile for sRGB */
#define PNG_OPTION_NEXT 6 /* Next option - numbers must be even */
/* Return values: NOTE: there are four values and 'off' is *not* zero */
#define PNG_OPTION_UNSET 0 /* Unset - defaults to off */
#define PNG_OPTION_INVALID 1 /* Option number out of range */
#define PNG_OPTION_OFF 2
#define PNG_OPTION_ON 3
PNG_EXPORT(244, int, png_set_option, (png_structrp png_ptr, int option,
int onoff));
#endif /* SET_OPTION */
/*******************************************************************************
* END OF HARDWARE AND SOFTWARE OPTIONS
******************************************************************************/
/* Maintainer: Put new public prototypes here ^, in libpng.3, in project
* defs, and in scripts/symbols.def.
*/
/* The last ordinal number (this is the *last* one already used; the next
* one to use is one more than this.)
*/
#ifdef PNG_EXPORT_LAST_ORDINAL
PNG_EXPORT_LAST_ORDINAL(244);
#endif
src/Source/LibPNG/pngconf.h view on Meta::CPAN
/* pngconf.h - machine configurable file for libpng
*
* libpng version 1.6.16,December 22, 2014
*
* Copyright (c) 1998-2014 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*
*/
/* Any machine specific code is near the front of this file, so if you
* are configuring libpng for a machine, you may want to read the section
* starting here down to where it starts to typedef png_color, png_text,
* and png_info.
*/
#ifndef PNGCONF_H
#define PNGCONF_H
/* To do: Do all of this in scripts/pnglibconf.dfa */
#ifdef PNG_SAFE_LIMITS_SUPPORTED
# ifdef PNG_USER_WIDTH_MAX
# undef PNG_USER_WIDTH_MAX
# define PNG_USER_WIDTH_MAX 1000000L
# endif
# ifdef PNG_USER_HEIGHT_MAX
# undef PNG_USER_HEIGHT_MAX
# define PNG_USER_HEIGHT_MAX 1000000L
# endif
# ifdef PNG_USER_CHUNK_MALLOC_MAX
src/Source/LibPNG/pngconf.h view on Meta::CPAN
# define PNG_USER_CHUNK_MALLOC_MAX 4000000L
# endif
# ifdef PNG_USER_CHUNK_CACHE_MAX
# undef PNG_USER_CHUNK_CACHE_MAX
# define PNG_USER_CHUNK_CACHE_MAX 128
# endif
#endif
#ifndef PNG_BUILDING_SYMBOL_TABLE /* else includes may cause problems */
/* From libpng 1.6.0 libpng requires an ANSI X3.159-1989 ("ISOC90") compliant C
* compiler for correct compilation. The following header files are required by
* the standard. If your compiler doesn't provide these header files, or they
* do not match the standard, you will need to provide/improve them.
*/
#include <limits.h>
#include <stddef.h>
/* Library header files. These header files are all defined by ISOC90; libpng
* expects conformant implementations, however, an ISOC90 conformant system need
* not provide these header files if the functionality cannot be implemented.
* In this case it will be necessary to disable the relevant parts of libpng in
* the build of pnglibconf.h.
*
* Prior to 1.6.0 string.h was included here; the API changes in 1.6.0 to not
* include this unnecessary header file.
*/
#ifdef PNG_STDIO_SUPPORTED
/* Required for the definition of FILE: */
# include <stdio.h>
#endif
src/Source/LibPNG/pngconf.h view on Meta::CPAN
# if PNG_DEFAULT_READ_MACROS
# define PNG_USE_READ_MACROS
# endif
#endif
/* COMPILER SPECIFIC OPTIONS.
*
* These options are provided so that a variety of difficult compilers
* can be used. Some are fixed at build time (e.g. PNG_API_RULE
* below) but still have compiler specific implementations, others
* may be changed on a per-file basis when compiling against libpng.
*/
/* The PNGARG macro was used in versions of libpng prior to 1.6.0 to protect
* against legacy (pre ISOC90) compilers that did not understand function
* prototypes. It is not required for modern C compilers.
*/
#ifndef PNGARG
# define PNGARG(arglist) arglist
#endif
/* Function calling conventions.
* =============================
* Normally it is not necessary to specify to the compiler how to call
* a function - it just does it - however on x86 systems derived from
* Microsoft and Borland C compilers ('IBM PC', 'DOS', 'Windows' systems
* and some others) there are multiple ways to call a function and the
* default can be changed on the compiler command line. For this reason
* libpng specifies the calling convention of every exported function and
* every function called via a user supplied function pointer. This is
* done in this file by defining the following macros:
*
* PNGAPI Calling convention for exported functions.
* PNGCBAPI Calling convention for user provided (callback) functions.
* PNGCAPI Calling convention used by the ANSI-C library (required
* for longjmp callbacks and sometimes used internally to
* specify the calling convention for zlib).
*
* These macros should never be overridden. If it is necessary to
src/Source/LibPNG/pngconf.h view on Meta::CPAN
* by setting PNG_API_RULE (which defaults to 0) to one of the values
* below to select the correct 'API' variants.
*
* PNG_API_RULE=0 Use PNGCAPI - the 'C' calling convention - throughout.
* This is correct in every known environment.
* PNG_API_RULE=1 Use the operating system convention for PNGAPI and
* the 'C' calling convention (from PNGCAPI) for
* callbacks (PNGCBAPI). This is no longer required
* in any known environment - if it has to be used
* please post an explanation of the problem to the
* libpng mailing list.
*
* These cases only differ if the operating system does not use the C
* calling convention, at present this just means the above cases
* (x86 DOS/Windows sytems) and, even then, this does not apply to
* Cygwin running on those systems.
*
* Note that the value must be defined in pnglibconf.h so that what
* the application uses to call the library matches the conventions
* set when building the library.
*/
/* Symbol export
* =============
* When building a shared library it is almost always necessary to tell
* the compiler which symbols to export. The png.h macro 'PNG_EXPORT'
* is used to mark the symbols. On some systems these symbols can be
* extracted at link time and need no special processing by the compiler,
* on other systems the symbols are flagged by the compiler and just
* the declaration requires a special tag applied (unfortunately) in a
* compiler dependent way. Some systems can do either.
*
* A small number of older systems also require a symbol from a DLL to
* be flagged to the program that calls it. This is a problem because
* we do not know in the header file included by application code that
* the symbol will come from a shared library, as opposed to a statically
* linked one. For this reason the application must tell us by setting
* the magic flag PNG_USE_DLL to turn on the special processing before
* it includes png.h.
*
* Four additional macros are used to make this happen:
*
* PNG_IMPEXP The magic (if any) to cause a symbol to be exported from
* the build or imported if PNG_USE_DLL is set - compiler
* and system specific.
*
* PNG_EXPORT_TYPE(type) A macro that pre or appends PNG_IMPEXP to
* 'type', compiler specific.
*
* PNG_DLL_EXPORT Set to the magic to use during a libpng build to
* make a symbol exported from the DLL. Not used in the
* public header files; see pngpriv.h for how it is used
* in the libpng build.
*
* PNG_DLL_IMPORT Set to the magic to force the libpng symbols to come
* from a DLL - used to define PNG_IMPEXP when
* PNG_USE_DLL is set.
*/
/* System specific discovery.
* ==========================
* This code is used at build time to find PNG_IMPEXP, the API settings
* and PNG_EXPORT_TYPE(), it may also set a macro to indicate the DLL
* import processing is possible. On Windows systems it also sets
* compiler-specific macros to the values required to change the calling
src/Source/LibPNG/pngconf.h view on Meta::CPAN
* a storage class (this is unlikely.)
*/
#ifndef PNG_FUNCTION
# define PNG_FUNCTION(type, name, args, attributes) attributes type name args
#endif
#ifndef PNG_EXPORT_TYPE
# define PNG_EXPORT_TYPE(type) PNG_IMPEXP type
#endif
/* The ordinal value is only relevant when preprocessing png.h for symbol
* table entries, so we discard it here. See the .dfn files in the
* scripts directory.
*/
#ifndef PNG_EXPORTA
# define PNG_EXPORTA(ordinal, type, name, args, attributes)\
PNG_FUNCTION(PNG_EXPORT_TYPE(type),(PNGAPI name),PNGARG(args), \
extern attributes)
#endif
src/Source/LibPNG/pngconf.h view on Meta::CPAN
#ifndef PNG_REMOVED
# define PNG_REMOVED(ordinal, type, name, args, attributes)
#endif
#ifndef PNG_CALLBACK
# define PNG_CALLBACK(type, name, args) type (PNGCBAPI name) PNGARG(args)
#endif
/* Support for compiler specific function attributes. These are used
* so that where compiler support is available incorrect use of API
* functions in png.h will generate compiler warnings.
*
* Added at libpng-1.2.41.
*/
#ifndef PNG_NO_PEDANTIC_WARNINGS
# ifndef PNG_PEDANTIC_WARNINGS_SUPPORTED
# define PNG_PEDANTIC_WARNINGS_SUPPORTED
# endif
#endif
#ifdef PNG_PEDANTIC_WARNINGS_SUPPORTED
/* Support for compiler specific function attributes. These are used
* so that where compiler support is available, incorrect use of API
* functions in png.h will generate compiler warnings. Added at libpng
* version 1.2.41. Disabling these removes the warnings but may also produce
* less efficient code.
*/
# if defined(__clang__) && defined(__has_attribute)
/* Clang defines both __clang__ and __GNUC__. Check __clang__ first. */
# if !defined(PNG_USE_RESULT) && __has_attribute(__warn_unused_result__)
# define PNG_USE_RESULT __attribute__((__warn_unused_result__))
# endif
# if !defined(PNG_NORETURN) && __has_attribute(__noreturn__)
# define PNG_NORETURN __attribute__((__noreturn__))
src/Source/LibPNG/pngconf.h view on Meta::CPAN
# if !defined(PNG_ALLOCATED) && __has_attribute(__malloc__)
# define PNG_ALLOCATED __attribute__((__malloc__))
# endif
# if !defined(PNG_DEPRECATED) && __has_attribute(__deprecated__)
# define PNG_DEPRECATED __attribute__((__deprecated__))
# endif
# if !defined(PNG_PRIVATE)
# ifdef __has_extension
# if __has_extension(attribute_unavailable_with_message)
# define PNG_PRIVATE __attribute__((__unavailable__(\
"This function is not exported by libpng.")))
# endif
# endif
# endif
# ifndef PNG_RESTRICT
# define PNG_RESTRICT __restrict
# endif
# elif defined(__GNUC__)
# ifndef PNG_USE_RESULT
# define PNG_USE_RESULT __attribute__((__warn_unused_result__))
src/Source/LibPNG/pngconf.h view on Meta::CPAN
# if __GNUC__ >= 3
# ifndef PNG_ALLOCATED
# define PNG_ALLOCATED __attribute__((__malloc__))
# endif
# ifndef PNG_DEPRECATED
# define PNG_DEPRECATED __attribute__((__deprecated__))
# endif
# ifndef PNG_PRIVATE
# if 0 /* Doesn't work so we use deprecated instead*/
# define PNG_PRIVATE \
__attribute__((warning("This function is not exported by libpng.")))
# else
# define PNG_PRIVATE \
__attribute__((__deprecated__))
# endif
# endif
# if ((__GNUC__ > 3) || !defined(__GNUC_MINOR__) || (__GNUC_MINOR__ >= 1))
# ifndef PNG_RESTRICT
# define PNG_RESTRICT __restrict
# endif
# endif /* __GNUC__.__GNUC_MINOR__ > 3.0 */
src/Source/LibPNG/pngconf.h view on Meta::CPAN
#ifndef PNG_USE_RESULT
# define PNG_USE_RESULT /* The result of this function must be checked */
#endif
#ifndef PNG_NORETURN
# define PNG_NORETURN /* This function does not return */
#endif
#ifndef PNG_ALLOCATED
# define PNG_ALLOCATED /* The result of the function is new memory */
#endif
#ifndef PNG_PRIVATE
# define PNG_PRIVATE /* This is a private libpng function */
#endif
#ifndef PNG_RESTRICT
# define PNG_RESTRICT /* The C99 "restrict" feature */
#endif
#ifndef PNG_FP_EXPORT /* A floating point API. */
# ifdef PNG_FLOATING_POINT_SUPPORTED
# define PNG_FP_EXPORT(ordinal, type, name, args)\
PNG_EXPORT(ordinal, type, name, args);
# else /* No floating point APIs */
src/Source/LibPNG/pngconf.h view on Meta::CPAN
PNG_EXPORT(ordinal, type, name, args);
# else /* No fixed point APIs */
# define PNG_FIXED_EXPORT(ordinal, type, name, args)
# endif
#endif
#ifndef PNG_BUILDING_SYMBOL_TABLE
/* Some typedefs to get us started. These should be safe on most of the common
* platforms.
*
* png_uint_32 and png_int_32 may, currently, be larger than required to hold a
* 32-bit value however this is not normally advisable.
*
* png_uint_16 and png_int_16 should always be two bytes in size - this is
* verified at library build time.
*
* png_byte must always be one byte in size.
*
* The checks below use constants from limits.h, as defined by the ISOC90
* standard.
*/
#if CHAR_BIT == 8 && UCHAR_MAX == 255
typedef unsigned char png_byte;
#else
# error "libpng requires 8 bit bytes"
#endif
#if INT_MIN == -32768 && INT_MAX == 32767
typedef int png_int_16;
#elif SHRT_MIN == -32768 && SHRT_MAX == 32767
typedef short png_int_16;
#else
# error "libpng requires a signed 16 bit type"
#endif
#if UINT_MAX == 65535
typedef unsigned int png_uint_16;
#elif USHRT_MAX == 65535
typedef unsigned short png_uint_16;
#else
# error "libpng requires an unsigned 16 bit type"
#endif
#if INT_MIN < -2147483646 && INT_MAX > 2147483646
typedef int png_int_32;
#elif LONG_MIN < -2147483646 && LONG_MAX > 2147483646
typedef long int png_int_32;
#else
# error "libpng requires a signed 32 bit (or more) type"
#endif
#if UINT_MAX > 4294967294
typedef unsigned int png_uint_32;
#elif ULONG_MAX > 4294967294
typedef unsigned long int png_uint_32;
#else
# error "libpng requires an unsigned 32 bit (or more) type"
#endif
/* Prior to 1.6.0 it was possible to disable the use of size_t, 1.6.0, however,
* requires an ISOC90 compiler and relies on consistent behavior of sizeof.
*/
typedef size_t png_size_t;
typedef ptrdiff_t png_ptrdiff_t;
/* libpng needs to know the maximum value of 'size_t' and this controls the
* definition of png_alloc_size_t, below. This maximum value of size_t limits
* but does not control the maximum allocations the library makes - there is
* direct application control of this through png_set_user_limits().
*/
#ifndef PNG_SMALL_SIZE_T
/* Compiler specific tests for systems where size_t is known to be less than
* 32 bits (some of these systems may no longer work because of the lack of
* 'far' support; see above.)
*/
# if (defined(__TURBOC__) && !defined(__FLAT__)) ||\
(defined(_MSC_VER) && defined(MAXSEG_64K))
# define PNG_SMALL_SIZE_T
# endif
#endif
/* png_alloc_size_t is guaranteed to be no smaller than png_size_t, and no
* smaller than png_uint_32. Casts from png_size_t or png_uint_32 to
* png_alloc_size_t are not necessary; in fact, it is recommended not to use
* them at all so that the compiler can complain when something turns out to be
* problematic.
*
* Casts in the other direction (from png_alloc_size_t to png_size_t or
* png_uint_32) should be explicitly applied; however, we do not expect to
* encounter practical situations that require such conversions.
*
* PNG_SMALL_SIZE_T must be defined if the maximum value of size_t is less than
* 4294967295 - i.e. less than the maximum value of png_uint_32.
*/
#ifdef PNG_SMALL_SIZE_T
typedef png_uint_32 png_alloc_size_t;
#else
typedef png_size_t png_alloc_size_t;
#endif
/* Prior to 1.6.0 libpng offered limited support for Microsoft C compiler
* implementations of Intel CPU specific support of user-mode segmented address
* spaces, where 16-bit pointers address more than 65536 bytes of memory using
* separate 'segment' registers. The implementation requires two different
* types of pointer (only one of which includes the segment value.)
*
* If required this support is available in version 1.2 of libpng and may be
* available in versions through 1.5, although the correctness of the code has
* not been verified recently.
*/
/* Typedef for floating-point numbers that are converted to fixed-point with a
* multiple of 100,000, e.g., gamma
*/
typedef png_int_32 png_fixed_point;
/* Add typedefs for pointers */
typedef void * png_voidp;
typedef const void * png_const_voidp;
typedef png_byte * png_bytep;
typedef const png_byte * png_const_bytep;
typedef png_uint_32 * png_uint_32p;
typedef const png_uint_32 * png_const_uint_32p;
typedef png_int_32 * png_int_32p;
typedef const png_int_32 * png_const_int_32p;
typedef png_uint_16 * png_uint_16p;
typedef const png_uint_16 * png_const_uint_16p;
typedef png_int_16 * png_int_16p;
typedef const png_int_16 * png_const_int_16p;
typedef char * png_charp;
typedef const char * png_const_charp;
typedef png_fixed_point * png_fixed_point_p;
typedef const png_fixed_point * png_const_fixed_point_p;
typedef png_size_t * png_size_tp;
typedef const png_size_t * png_const_size_tp;
#ifdef PNG_STDIO_SUPPORTED
typedef FILE * png_FILE_p;
#endif
#ifdef PNG_FLOATING_POINT_SUPPORTED
typedef double * png_doublep;
typedef const double * png_const_doublep;
#endif
/* Pointers to pointers; i.e. arrays */
typedef png_byte * * png_bytepp;
typedef png_uint_32 * * png_uint_32pp;
typedef png_int_32 * * png_int_32pp;
typedef png_uint_16 * * png_uint_16pp;
typedef png_int_16 * * png_int_16pp;
typedef const char * * png_const_charpp;
typedef char * * png_charpp;
typedef png_fixed_point * * png_fixed_point_pp;
#ifdef PNG_FLOATING_POINT_SUPPORTED
typedef double * * png_doublepp;
#endif
/* Pointers to pointers to pointers; i.e., pointer to array */
typedef char * * * png_charppp;
#endif /* PNG_BUILDING_SYMBOL_TABLE */
#endif /* PNGCONF_H */
src/Source/LibPNG/pngdebug.h view on Meta::CPAN
/* pngdebug.h - Debugging macros for libpng, also used in pngtest.c
*
* Copyright (c) 1998-2013 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
* Last changed in libpng 1.6.8 [December 19, 2013]
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*/
/* Define PNG_DEBUG at compile time for debugging information. Higher
* numbers for PNG_DEBUG mean more debugging information. This has
* only been added since version 0.95 so it is not implemented throughout
* libpng yet, but more support will be added as needed.
*
* png_debug[1-2]?(level, message ,arg{0-2})
* Expands to a statement (either a simple expression or a compound
* do..while(0) statement) that outputs a message with parameter
* substitution if PNG_DEBUG is defined to 2 or more. If PNG_DEBUG
* is undefined, 0 or 1 every png_debug expands to a simple expression
* (actually ((void)0)).
*
* level: level of detail of message, starting at 0. A level 'n'
* message is preceded by 'n' 3-space indentations (not implemented
* on Microsoft compilers unless PNG_DEBUG_FILE is also
* defined, to allow debug DLL compilation with no standard IO).
* message: a printf(3) style text string. A trailing '\n' is added
* to the message.
* arg: 0 to 2 arguments for printf(3) style substitution in message.
*/
#ifndef PNGDEBUG_H
#define PNGDEBUG_H
/* These settings control the formatting of messages in png.c and pngerror.c */
/* Moved to pngdebug.h at 1.5.0 */
# ifndef PNG_LITERAL_SHARP
# define PNG_LITERAL_SHARP 0x23
# endif
# ifndef PNG_LITERAL_LEFT_SQUARE_BRACKET
# define PNG_LITERAL_LEFT_SQUARE_BRACKET 0x5b
# endif
# ifndef PNG_LITERAL_RIGHT_SQUARE_BRACKET
# define PNG_LITERAL_RIGHT_SQUARE_BRACKET 0x5d
# endif
# ifndef PNG_STRING_NEWLINE
src/Source/LibPNG/pngdebug.h view on Meta::CPAN
# endif
#ifdef PNG_DEBUG
# if (PNG_DEBUG > 0)
# if !defined(PNG_DEBUG_FILE) && defined(_MSC_VER)
# include <crtdbg.h>
# if (PNG_DEBUG > 1)
# ifndef _DEBUG
# define _DEBUG
# endif
# ifndef png_debug
# define png_debug(l,m) _RPT0(_CRT_WARN,m PNG_STRING_NEWLINE)
# endif
# ifndef png_debug1
# define png_debug1(l,m,p1) _RPT1(_CRT_WARN,m PNG_STRING_NEWLINE,p1)
# endif
# ifndef png_debug2
# define png_debug2(l,m,p1,p2) \
_RPT2(_CRT_WARN,m PNG_STRING_NEWLINE,p1,p2)
# endif
# endif
# else /* PNG_DEBUG_FILE || !_MSC_VER */
# ifndef PNG_STDIO_SUPPORTED
# include <stdio.h> /* not included yet */
# endif
# ifndef PNG_DEBUG_FILE
# define PNG_DEBUG_FILE stderr
# endif /* PNG_DEBUG_FILE */
# if (PNG_DEBUG > 1)
# ifdef __STDC__
# ifndef png_debug
# define png_debug(l,m) \
do { \
int num_tabs=l; \
fprintf(PNG_DEBUG_FILE,"%s" m PNG_STRING_NEWLINE,(num_tabs==1 ? " " : \
(num_tabs==2 ? " " : (num_tabs>2 ? " " : "")))); \
} while (0)
# endif
# ifndef png_debug1
# define png_debug1(l,m,p1) \
do { \
int num_tabs=l; \
fprintf(PNG_DEBUG_FILE,"%s" m PNG_STRING_NEWLINE,(num_tabs==1 ? " " : \
(num_tabs==2 ? " " : (num_tabs>2 ? " " : ""))),p1); \
} while (0)
# endif
# ifndef png_debug2
# define png_debug2(l,m,p1,p2) \
do { \
int num_tabs=l; \
fprintf(PNG_DEBUG_FILE,"%s" m PNG_STRING_NEWLINE,(num_tabs==1 ? " " : \
(num_tabs==2 ? " " : (num_tabs>2 ? " " : ""))),p1,p2);\
} while (0)
# endif
# else /* __STDC __ */
# ifndef png_debug
# define png_debug(l,m) \
do { \
int num_tabs=l; \
char format[256]; \
snprintf(format,256,"%s%s%s",(num_tabs==1 ? "\t" : \
(num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))), \
m,PNG_STRING_NEWLINE); \
fprintf(PNG_DEBUG_FILE,format); \
} while (0)
# endif
# ifndef png_debug1
# define png_debug1(l,m,p1) \
do { \
int num_tabs=l; \
char format[256]; \
snprintf(format,256,"%s%s%s",(num_tabs==1 ? "\t" : \
(num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))), \
m,PNG_STRING_NEWLINE); \
fprintf(PNG_DEBUG_FILE,format,p1); \
} while (0)
# endif
# ifndef png_debug2
# define png_debug2(l,m,p1,p2) \
do { \
int num_tabs=l; \
char format[256]; \
snprintf(format,256,"%s%s%s",(num_tabs==1 ? "\t" : \
(num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))), \
m,PNG_STRING_NEWLINE); \
fprintf(PNG_DEBUG_FILE,format,p1,p2); \
} while (0)
# endif
# endif /* __STDC __ */
# endif /* (PNG_DEBUG > 1) */
# endif /* _MSC_VER */
# endif /* (PNG_DEBUG > 0) */
#endif /* PNG_DEBUG */
#ifndef png_debug
# define png_debug(l, m) ((void)0)
#endif
#ifndef png_debug1
# define png_debug1(l, m, p1) ((void)0)
#endif
#ifndef png_debug2
# define png_debug2(l, m, p1, p2) ((void)0)
#endif
#endif /* PNGDEBUG_H */
src/Source/LibPNG/pngerror.c view on Meta::CPAN
/* pngerror.c - stub functions for i/o and memory allocation
*
* Last changed in libpng 1.6.15 [November 20, 2014]
* Copyright (c) 1998-2014 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*
* This file provides a location for all error handling. Users who
* need special error handling are expected to write replacement functions
* and use png_set_error_fn() to use those functions. See the instructions
* at each function.
*/
#include "pngpriv.h"
#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
static PNG_FUNCTION(void, png_default_error,PNGARG((png_const_structrp png_ptr,
png_const_charp error_message)),PNG_NORETURN);
#ifdef PNG_WARNINGS_SUPPORTED
static void /* PRIVATE */
png_default_warning PNGARG((png_const_structrp png_ptr,
png_const_charp warning_message));
#endif /* WARNINGS */
/* This function is called whenever there is a fatal error. This function
* should not be changed. If there is a need to handle errors differently,
* you should supply a replacement error function and use png_set_error_fn()
* to replace the error function at run-time.
*/
#ifdef PNG_ERROR_TEXT_SUPPORTED
PNG_FUNCTION(void,PNGAPI
png_error,(png_const_structrp png_ptr, png_const_charp error_message),
PNG_NORETURN)
{
#ifdef PNG_ERROR_NUMBERS_SUPPORTED
char msg[16];
if (png_ptr != NULL)
{
if ((png_ptr->flags &
(PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT)) != 0
{
if (*error_message == PNG_LITERAL_SHARP)
{
/* Strip "#nnnn " from beginning of error message. */
int offset;
for (offset = 1; offset<15; offset++)
if (error_message[offset] == ' ')
break;
if ((png_ptr->flags & PNG_FLAG_STRIP_ERROR_TEXT) != 0)
{
int i;
for (i = 0; i < offset - 1; i++)
msg[i] = error_message[i + 1];
msg[i - 1] = '\0';
error_message = msg;
}
else
error_message += offset;
}
else
{
if ((png_ptr->flags & PNG_FLAG_STRIP_ERROR_TEXT) != 0)
{
msg[0] = '0';
msg[1] = '\0';
error_message = msg;
}
}
}
}
#endif
if (png_ptr != NULL && png_ptr->error_fn != NULL)
(*(png_ptr->error_fn))(png_constcast(png_structrp,png_ptr),
error_message);
/* If the custom handler doesn't exist, or if it returns,
use the default handler, which will not return. */
png_default_error(png_ptr, error_message);
}
#else
PNG_FUNCTION(void,PNGAPI
png_err,(png_const_structrp png_ptr),PNG_NORETURN)
{
/* Prior to 1.5.2 the error_fn received a NULL pointer, expressed
* erroneously as '\0', instead of the empty string "". This was
* apparently an error, introduced in libpng-1.2.20, and png_default_error
* will crash in this case.
*/
if (png_ptr != NULL && png_ptr->error_fn != NULL)
(*(png_ptr->error_fn))(png_constcast(png_structrp,png_ptr), "");
/* If the custom handler doesn't exist, or if it returns,
use the default handler, which will not return. */
png_default_error(png_ptr, "");
}
#endif /* ERROR_TEXT */
/* Utility to safely appends strings to a buffer. This never errors out so
* error checking is not required in the caller.
*/
size_t
png_safecat(png_charp buffer, size_t bufsize, size_t pos,
png_const_charp string)
{
if (buffer != NULL && pos < bufsize)
{
if (string != NULL)
while (*string != '\0' && pos < bufsize-1)
buffer[pos++] = *string++;
buffer[pos] = '\0';
}
return pos;
}
#if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_TIME_RFC1123_SUPPORTED)
/* Utility to dump an unsigned value into a buffer, given a start pointer and
* and end pointer (which should point just *beyond* the end of the buffer!)
* Returns the pointer to the start of the formatted string.
*/
png_charp
png_format_number(png_const_charp start, png_charp end, int format,
png_alloc_size_t number)
{
int count = 0; /* number of digits output */
int mincount = 1; /* minimum number required */
int output = 0; /* digit output (for the fixed point format) */
*--end = '\0';
/* This is written so that the loop always runs at least once, even with
* number zero.
*/
src/Source/LibPNG/pngerror.c view on Meta::CPAN
}
return end;
}
#endif
#ifdef PNG_WARNINGS_SUPPORTED
/* This function is called whenever there is a non-fatal error. This function
* should not be changed. If there is a need to handle warnings differently,
* you should supply a replacement warning function and use
* png_set_error_fn() to replace the warning function at run-time.
*/
void PNGAPI
png_warning(png_const_structrp png_ptr, png_const_charp warning_message)
{
int offset = 0;
if (png_ptr != NULL)
{
#ifdef PNG_ERROR_NUMBERS_SUPPORTED
if ((png_ptr->flags &
(PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT)) != 0)
#endif
{
if (*warning_message == PNG_LITERAL_SHARP)
{
for (offset = 1; offset < 15; offset++)
if (warning_message[offset] == ' ')
break;
}
}
}
if (png_ptr != NULL && png_ptr->warning_fn != NULL)
(*(png_ptr->warning_fn))(png_constcast(png_structrp,png_ptr),
warning_message + offset);
else
png_default_warning(png_ptr, warning_message + offset);
}
/* These functions support 'formatted' warning messages with up to
* PNG_WARNING_PARAMETER_COUNT parameters. In the format string the parameter
* is introduced by @<number>, where 'number' starts at 1. This follows the
* standard established by X/Open for internationalizable error messages.
*/
void
png_warning_parameter(png_warning_parameters p, int number,
png_const_charp string)
{
if (number > 0 && number <= PNG_WARNING_PARAMETER_COUNT)
(void)png_safecat(p[number-1], (sizeof p[number-1]), 0, string);
}
void
png_warning_parameter_unsigned(png_warning_parameters p, int number, int format,
png_alloc_size_t value)
{
char buffer[PNG_NUMBER_BUFFER_SIZE];
png_warning_parameter(p, number, PNG_FORMAT_NUMBER(buffer, format, value));
}
void
png_warning_parameter_signed(png_warning_parameters p, int number, int format,
png_int_32 value)
{
png_alloc_size_t u;
png_charp str;
char buffer[PNG_NUMBER_BUFFER_SIZE];
/* Avoid overflow by doing the negate in a png_alloc_size_t: */
u = (png_alloc_size_t)value;
if (value < 0)
u = ~u + 1;
str = PNG_FORMAT_NUMBER(buffer, format, u);
if (value < 0 && str > buffer)
*--str = '-';
png_warning_parameter(p, number, str);
}
void
png_formatted_warning(png_const_structrp png_ptr, png_warning_parameters p,
png_const_charp message)
{
/* The internal buffer is just 192 bytes - enough for all our messages,
* overflow doesn't happen because this code checks! If someone figures
* out how to send us a message longer than 192 bytes, all that will
* happen is that the message will be truncated appropriately.
*/
size_t i = 0; /* Index in the msg[] buffer: */
char msg[192];
/* Each iteration through the following loop writes at most one character
src/Source/LibPNG/pngerror.c view on Meta::CPAN
* parameter to use.
*/
while (valid_parameters[parameter] != parameter_char &&
valid_parameters[parameter] != '\0')
++parameter;
/* If the parameter digit is out of range it will just get printed. */
if (parameter < PNG_WARNING_PARAMETER_COUNT)
{
/* Append this parameter */
png_const_charp parm = p[parameter];
png_const_charp pend = p[parameter] + (sizeof p[parameter]);
/* No need to copy the trailing '\0' here, but there is no guarantee
* that parm[] has been initialized, so there is no guarantee of a
* trailing '\0':
*/
while (i<(sizeof msg)-1 && *parm != '\0' && parm < pend)
msg[i++] = *parm++;
/* Consume the parameter digit too: */
++message;
src/Source/LibPNG/pngerror.c view on Meta::CPAN
msg[i++] = *message++;
}
/* i is always less than (sizeof msg), so: */
msg[i] = '\0';
/* And this is the formatted message. It may be larger than
* PNG_MAX_ERROR_TEXT, but that is only used for 'chunk' errors and these
* are not (currently) formatted.
*/
png_warning(png_ptr, msg);
}
#endif /* WARNINGS */
#ifdef PNG_BENIGN_ERRORS_SUPPORTED
void PNGAPI
png_benign_error(png_const_structrp png_ptr, png_const_charp error_message)
{
if ((png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN) != 0)
{
# ifdef PNG_READ_SUPPORTED
if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
png_ptr->chunk_name != 0)
png_chunk_warning(png_ptr, error_message);
else
# endif
png_warning(png_ptr, error_message);
}
else
{
# ifdef PNG_READ_SUPPORTED
if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 &&
png_ptr->chunk_name != 0)
png_chunk_error(png_ptr, error_message);
else
# endif
png_error(png_ptr, error_message);
}
# ifndef PNG_ERROR_TEXT_SUPPORTED
PNG_UNUSED(error_message)
# endif
}
void /* PRIVATE */
png_app_warning(png_const_structrp png_ptr, png_const_charp error_message)
{
if ((png_ptr->flags & PNG_FLAG_APP_WARNINGS_WARN) != 0)
png_warning(png_ptr, error_message);
else
png_error(png_ptr, error_message);
# ifndef PNG_ERROR_TEXT_SUPPORTED
PNG_UNUSED(error_message)
# endif
}
void /* PRIVATE */
png_app_error(png_const_structrp png_ptr, png_const_charp error_message)
{
if ((png_ptr->flags & PNG_FLAG_APP_ERRORS_WARN) != 0)
png_warning(png_ptr, error_message);
else
png_error(png_ptr, error_message);
# ifndef PNG_ERROR_TEXT_SUPPORTED
PNG_UNUSED(error_message)
# endif
}
#endif /* BENIGN_ERRORS */
#define PNG_MAX_ERROR_TEXT 196 /* Currently limited by profile_error in png.c */
#if defined(PNG_WARNINGS_SUPPORTED) || \
(defined(PNG_READ_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED))
/* These utilities are used internally to build an error message that relates
* to the current chunk. The chunk name comes from png_ptr->chunk_name,
* which is used to prefix the message. The message is limited in length
* to 63 bytes. The name characters are output as hex digits wrapped in []
* if the character is invalid.
*/
#define isnonalpha(c) ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97))
static PNG_CONST char png_digit[16] = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'A', 'B', 'C', 'D', 'E', 'F'
};
static void /* PRIVATE */
png_format_buffer(png_const_structrp png_ptr, png_charp buffer, png_const_charp
error_message)
{
png_uint_32 chunk_name = png_ptr->chunk_name;
int iout = 0, ishift = 24;
while (ishift >= 0)
{
int c = (int)(chunk_name >> ishift) & 0xff;
ishift -= 8;
if (isnonalpha(c) != 0)
{
buffer[iout++] = PNG_LITERAL_LEFT_SQUARE_BRACKET;
buffer[iout++] = png_digit[(c & 0xf0) >> 4];
buffer[iout++] = png_digit[c & 0x0f];
buffer[iout++] = PNG_LITERAL_RIGHT_SQUARE_BRACKET;
}
else
{
buffer[iout++] = (char)c;
}
}
if (error_message == NULL)
src/Source/LibPNG/pngerror.c view on Meta::CPAN
buffer[iout++] = error_message[iin++];
/* iin < PNG_MAX_ERROR_TEXT, so the following is safe: */
buffer[iout] = '\0';
}
}
#endif /* WARNINGS || ERROR_TEXT */
#if defined(PNG_READ_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED)
PNG_FUNCTION(void,PNGAPI
png_chunk_error,(png_const_structrp png_ptr, png_const_charp error_message),
PNG_NORETURN)
{
char msg[18+PNG_MAX_ERROR_TEXT];
if (png_ptr == NULL)
png_error(png_ptr, error_message);
else
{
png_format_buffer(png_ptr, msg, error_message);
png_error(png_ptr, msg);
}
}
#endif /* READ && ERROR_TEXT */
#ifdef PNG_WARNINGS_SUPPORTED
void PNGAPI
png_chunk_warning(png_const_structrp png_ptr, png_const_charp warning_message)
{
char msg[18+PNG_MAX_ERROR_TEXT];
if (png_ptr == NULL)
png_warning(png_ptr, warning_message);
else
{
png_format_buffer(png_ptr, msg, warning_message);
png_warning(png_ptr, msg);
}
}
#endif /* WARNINGS */
#ifdef PNG_READ_SUPPORTED
#ifdef PNG_BENIGN_ERRORS_SUPPORTED
void PNGAPI
png_chunk_benign_error(png_const_structrp png_ptr, png_const_charp
error_message)
{
if ((png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN) != 0)
png_chunk_warning(png_ptr, error_message);
else
png_chunk_error(png_ptr, error_message);
# ifndef PNG_ERROR_TEXT_SUPPORTED
PNG_UNUSED(error_message)
# endif
}
#endif
#endif /* READ */
void /* PRIVATE */
png_chunk_report(png_const_structrp png_ptr, png_const_charp message, int error)
{
# ifndef PNG_WARNINGS_SUPPORTED
PNG_UNUSED(message)
# endif
/* This is always supported, but for just read or just write it
* unconditionally does the right thing.
*/
# if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED)
if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0)
# endif
# ifdef PNG_READ_SUPPORTED
{
if (error < PNG_CHUNK_ERROR)
png_chunk_warning(png_ptr, message);
else
png_chunk_benign_error(png_ptr, message);
}
# endif
# if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED)
else if ((png_ptr->mode & PNG_IS_READ_STRUCT) == 0)
# endif
# ifdef PNG_WRITE_SUPPORTED
{
if (error < PNG_CHUNK_WRITE_ERROR)
png_app_warning(png_ptr, message);
else
png_app_error(png_ptr, message);
}
# endif
}
#ifdef PNG_ERROR_TEXT_SUPPORTED
#ifdef PNG_FLOATING_POINT_SUPPORTED
PNG_FUNCTION(void,
png_fixed_error,(png_const_structrp png_ptr, png_const_charp name),PNG_NORETURN)
{
# define fixed_message "fixed point overflow in "
# define fixed_message_ln ((sizeof fixed_message)-1)
int iin;
char msg[fixed_message_ln+PNG_MAX_ERROR_TEXT];
memcpy(msg, fixed_message, fixed_message_ln);
iin = 0;
if (name != NULL)
while (iin < (PNG_MAX_ERROR_TEXT-1) && name[iin] != 0)
{
msg[fixed_message_ln + iin] = name[iin];
++iin;
}
msg[fixed_message_ln + iin] = 0;
png_error(png_ptr, msg);
}
#endif
#endif
#ifdef PNG_SETJMP_SUPPORTED
/* This API only exists if ANSI-C style error handling is used,
* otherwise it is necessary for png_default_error to be overridden.
*/
jmp_buf* PNGAPI
png_set_longjmp_fn(png_structrp png_ptr, png_longjmp_ptr longjmp_fn,
size_t jmp_buf_size)
{
/* From libpng 1.6.0 the app gets one chance to set a 'jmpbuf_size' value
* and it must not change after that. Libpng doesn't care how big the
* buffer is, just that it doesn't change.
*
* If the buffer size is no *larger* than the size of jmp_buf when libpng is
* compiled a built in jmp_buf is returned; this preserves the pre-1.6.0
* semantics that this call will not fail. If the size is larger, however,
* the buffer is allocated and this may fail, causing the function to return
* NULL.
*/
if (png_ptr == NULL)
return NULL;
if (png_ptr->jmp_buf_ptr == NULL)
{
png_ptr->jmp_buf_size = 0; /* not allocated */
if (jmp_buf_size <= (sizeof png_ptr->jmp_buf_local))
png_ptr->jmp_buf_ptr = &png_ptr->jmp_buf_local;
else
{
png_ptr->jmp_buf_ptr = png_voidcast(jmp_buf *,
png_malloc_warn(png_ptr, jmp_buf_size));
if (png_ptr->jmp_buf_ptr == NULL)
return NULL; /* new NULL return on OOM */
png_ptr->jmp_buf_size = jmp_buf_size;
}
}
else /* Already allocated: check the size */
{
size_t size = png_ptr->jmp_buf_size;
if (size == 0)
{
size = (sizeof png_ptr->jmp_buf_local);
if (png_ptr->jmp_buf_ptr != &png_ptr->jmp_buf_local)
{
/* This is an internal error in libpng: somehow we have been left
* with a stack allocated jmp_buf when the application regained
* control. It's always possible to fix this up, but for the moment
* this is a png_error because that makes it easy to detect.
*/
png_error(png_ptr, "Libpng jmp_buf still allocated");
/* png_ptr->jmp_buf_ptr = &png_ptr->jmp_buf_local; */
}
}
if (size != jmp_buf_size)
{
png_warning(png_ptr, "Application jmp_buf size changed");
return NULL; /* caller will probably crash: no choice here */
}
}
/* Finally fill in the function, now we have a satisfactory buffer. It is
* valid to change the function on every call.
*/
png_ptr->longjmp_fn = longjmp_fn;
return png_ptr->jmp_buf_ptr;
}
void /* PRIVATE */
png_free_jmpbuf(png_structrp png_ptr)
{
if (png_ptr != NULL)
{
jmp_buf *jb = png_ptr->jmp_buf_ptr;
/* A size of 0 is used to indicate a local, stack, allocation of the
* pointer; used here and in png.c
*/
if (jb != NULL && png_ptr->jmp_buf_size > 0)
{
/* This stuff is so that a failure to free the error control structure
* does not leave libpng in a state with no valid error handling: the
* free always succeeds, if there is an error it gets ignored.
*/
if (jb != &png_ptr->jmp_buf_local)
{
/* Make an internal, libpng, jmp_buf to return here */
jmp_buf free_jmp_buf;
if (!setjmp(free_jmp_buf))
{
png_ptr->jmp_buf_ptr = &free_jmp_buf; /* come back here */
png_ptr->jmp_buf_size = 0; /* stack allocation */
png_ptr->longjmp_fn = longjmp;
png_free(png_ptr, jb); /* Return to setjmp on error */
}
}
}
/* *Always* cancel everything out: */
png_ptr->jmp_buf_size = 0;
png_ptr->jmp_buf_ptr = NULL;
png_ptr->longjmp_fn = 0;
}
}
#endif
/* This is the default error handling function. Note that replacements for
* this function MUST NOT RETURN, or the program will likely crash. This
* function is used by default, or if the program supplies NULL for the
* error function pointer in png_set_error_fn().
*/
static PNG_FUNCTION(void /* PRIVATE */,
png_default_error,(png_const_structrp png_ptr, png_const_charp error_message),
PNG_NORETURN)
{
#ifdef PNG_CONSOLE_IO_SUPPORTED
#ifdef PNG_ERROR_NUMBERS_SUPPORTED
/* Check on NULL only added in 1.5.4 */
if (error_message != NULL && *error_message == PNG_LITERAL_SHARP)
{
/* Strip "#nnnn " from beginning of error message. */
int offset;
char error_number[16];
for (offset = 0; offset<15; offset++)
{
error_number[offset] = error_message[offset + 1];
if (error_message[offset] == ' ')
break;
}
if ((offset > 1) && (offset < 15))
{
error_number[offset - 1] = '\0';
fprintf(stderr, "libpng error no. %s: %s",
error_number, error_message + offset + 1);
fprintf(stderr, PNG_STRING_NEWLINE);
}
else
{
fprintf(stderr, "libpng error: %s, offset=%d",
error_message, offset);
fprintf(stderr, PNG_STRING_NEWLINE);
}
}
else
#endif
{
fprintf(stderr, "libpng error: %s", error_message ? error_message :
"undefined");
fprintf(stderr, PNG_STRING_NEWLINE);
}
#else
PNG_UNUSED(error_message) /* Make compiler happy */
#endif
png_longjmp(png_ptr, 1);
}
PNG_FUNCTION(void,PNGAPI
png_longjmp,(png_const_structrp png_ptr, int val),PNG_NORETURN)
{
#ifdef PNG_SETJMP_SUPPORTED
if (png_ptr != NULL && png_ptr->longjmp_fn != NULL &&
png_ptr->jmp_buf_ptr != NULL)
png_ptr->longjmp_fn(*png_ptr->jmp_buf_ptr, val);
#else
PNG_UNUSED(png_ptr)
PNG_UNUSED(val)
#endif
/* If control reaches this point, png_longjmp() must not return. The only
* choice is to terminate the whole process (or maybe the thread); to do
* this the ANSI-C abort() function is used unless a different method is
* implemented by overriding the default configuration setting for
* PNG_ABORT().
*/
PNG_ABORT();
}
#ifdef PNG_WARNINGS_SUPPORTED
/* This function is called when there is a warning, but the library thinks
* it can continue anyway. Replacement functions don't have to do anything
* here if you don't want them to. In the default configuration, png_ptr is
* not used, but it is passed in case it may be useful.
*/
static void /* PRIVATE */
png_default_warning(png_const_structrp png_ptr, png_const_charp warning_message)
{
#ifdef PNG_CONSOLE_IO_SUPPORTED
# ifdef PNG_ERROR_NUMBERS_SUPPORTED
if (*warning_message == PNG_LITERAL_SHARP)
{
int offset;
char warning_number[16];
for (offset = 0; offset < 15; offset++)
{
warning_number[offset] = warning_message[offset + 1];
if (warning_message[offset] == ' ')
break;
}
if ((offset > 1) && (offset < 15))
{
warning_number[offset + 1] = '\0';
fprintf(stderr, "libpng warning no. %s: %s",
warning_number, warning_message + offset);
fprintf(stderr, PNG_STRING_NEWLINE);
}
else
{
fprintf(stderr, "libpng warning: %s",
warning_message);
fprintf(stderr, PNG_STRING_NEWLINE);
}
}
else
# endif
{
fprintf(stderr, "libpng warning: %s", warning_message);
fprintf(stderr, PNG_STRING_NEWLINE);
}
#else
PNG_UNUSED(warning_message) /* Make compiler happy */
#endif
PNG_UNUSED(png_ptr) /* Make compiler happy */
}
#endif /* WARNINGS */
/* This function is called when the application wants to use another method
* of handling errors and warnings. Note that the error function MUST NOT
* return to the calling routine or serious problems will occur. The return
* method used in the default routine calls longjmp(png_ptr->jmp_buf_ptr, 1)
*/
void PNGAPI
png_set_error_fn(png_structrp png_ptr, png_voidp error_ptr,
png_error_ptr error_fn, png_error_ptr warning_fn)
{
if (png_ptr == NULL)
return;
png_ptr->error_ptr = error_ptr;
png_ptr->error_fn = error_fn;
#ifdef PNG_WARNINGS_SUPPORTED
png_ptr->warning_fn = warning_fn;
#else
PNG_UNUSED(warning_fn)
#endif
}
/* This function returns a pointer to the error_ptr associated with the user
* functions. The application should free any memory associated with this
* pointer before png_write_destroy and png_read_destroy are called.
*/
png_voidp PNGAPI
png_get_error_ptr(png_const_structrp png_ptr)
{
if (png_ptr == NULL)
return NULL;
return ((png_voidp)png_ptr->error_ptr);
}
#ifdef PNG_ERROR_NUMBERS_SUPPORTED
void PNGAPI
png_set_strip_error_numbers(png_structrp png_ptr, png_uint_32 strip_mode)
{
if (png_ptr != NULL)
{
png_ptr->flags &=
((~(PNG_FLAG_STRIP_ERROR_NUMBERS |
PNG_FLAG_STRIP_ERROR_TEXT))&strip_mode);
}
}
#endif
#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\
defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
/* Currently the above both depend on SETJMP_SUPPORTED, however it would be
* possible to implement without setjmp support just so long as there is some
* way to handle the error return here:
*/
PNG_FUNCTION(void /* PRIVATE */, (PNGCBAPI
png_safe_error),(png_structp png_nonconst_ptr, png_const_charp error_message),
PNG_NORETURN)
{
const png_const_structrp png_ptr = png_nonconst_ptr;
png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr);
/* An error is always logged here, overwriting anything (typically a warning)
* that is already there:
*/
if (image != NULL)
{
png_safecat(image->message, (sizeof image->message), 0, error_message);
image->warning_or_error |= PNG_IMAGE_ERROR;
/* Retrieve the jmp_buf from within the png_control, making this work for
* C++ compilation too is pretty tricky: C++ wants a pointer to the first
* element of a jmp_buf, but C doesn't tell us the type of that.
*/
if (image->opaque != NULL && image->opaque->error_buf != NULL)
longjmp(png_control_jmp_buf(image->opaque), 1);
/* Missing longjmp buffer, the following is to help debugging: */
{
size_t pos = png_safecat(image->message, (sizeof image->message), 0,
"bad longjmp: ");
png_safecat(image->message, (sizeof image->message), pos,
error_message);
}
}
/* Here on an internal programming error. */
abort();
}
#ifdef PNG_WARNINGS_SUPPORTED
void /* PRIVATE */ PNGCBAPI
png_safe_warning(png_structp png_nonconst_ptr, png_const_charp warning_message)
{
const png_const_structrp png_ptr = png_nonconst_ptr;
png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr);
/* A warning is only logged if there is no prior warning or error. */
if (image->warning_or_error == 0)
{
png_safecat(image->message, (sizeof image->message), 0, warning_message);
image->warning_or_error |= PNG_IMAGE_WARNING;
}
}
#endif
int /* PRIVATE */
png_safe_execute(png_imagep image_in, int (*function)(png_voidp), png_voidp arg)
{
volatile png_imagep image = image_in;
volatile int result;
volatile png_voidp saved_error_buf;
jmp_buf safe_jmpbuf;
/* Safely execute function(arg) with png_error returning to this function. */
saved_error_buf = image->opaque->error_buf;
result = setjmp(safe_jmpbuf) == 0;
if (result != 0)
{
image->opaque->error_buf = safe_jmpbuf;
result = function(arg);
}
image->opaque->error_buf = saved_error_buf;
/* And do the cleanup prior to any failure return. */
if (result == 0)
png_image_free(image);
return result;
}
#endif /* SIMPLIFIED READ || SIMPLIFIED_WRITE */
#endif /* READ || WRITE */
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