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src/Source/LibPNG/png.h view on Meta::CPAN
/*
* 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
* PNG_LIBPNG_VER_STRING, omitting any leading zero:
*/
#define PNG_LIBPNG_VER_BUILD 0
/* Release Status */
#define PNG_LIBPNG_BUILD_ALPHA 1
#define PNG_LIBPNG_BUILD_BETA 2
#define PNG_LIBPNG_BUILD_RC 3
#define PNG_LIBPNG_BUILD_STABLE 4
#define PNG_LIBPNG_BUILD_RELEASE_STATUS_MASK 7
/* Release-Specific Flags */
#define PNG_LIBPNG_BUILD_PATCH 8 /* Can be OR'ed with
PNG_LIBPNG_BUILD_STABLE only */
#define PNG_LIBPNG_BUILD_PRIVATE 16 /* Cannot be OR'ed with
PNG_LIBPNG_BUILD_SPECIAL */
#define PNG_LIBPNG_BUILD_SPECIAL 32 /* Cannot be OR'ed with
PNG_LIBPNG_BUILD_PRIVATE */
#define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_STABLE
/* Careful here. At one time, Guy wanted to use 082, but that would be octal.
* We must not include leading zeros.
* 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
*/
src/Source/LibPNG/png.h view on Meta::CPAN
#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,
src/Source/LibPNG/png.h view on Meta::CPAN
/* 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:
*
* a) As a small integer, value 0..255, contained in a single byte. For the
* alpha channel the original value is simply value/255. For the color or
* luminance channels the value is encoded according to the sRGB specification
* and matches the 8-bit format expected by typical display devices.
*
* The color/gray channels are not scaled (pre-multiplied) by the alpha
* channel and are suitable for passing to color management software.
*
* 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 */
#ifdef PNG_FORMAT_BGR_SUPPORTED
# define PNG_FORMAT_FLAG_BGR 0x10U /* BGR colors, else order is RGB */
#endif
#ifdef PNG_FORMAT_AFIRST_SUPPORTED
# define PNG_FORMAT_FLAG_AFIRST 0x20U /* alpha channel comes first */
#endif
/* Commonly used formats have predefined macros.
*
* First the single byte (sRGB) formats:
*/
#define PNG_FORMAT_GRAY 0
#define PNG_FORMAT_GA PNG_FORMAT_FLAG_ALPHA
#define PNG_FORMAT_AG (PNG_FORMAT_GA|PNG_FORMAT_FLAG_AFIRST)
#define PNG_FORMAT_RGB PNG_FORMAT_FLAG_COLOR
#define PNG_FORMAT_BGR (PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_BGR)
#define PNG_FORMAT_RGBA (PNG_FORMAT_RGB|PNG_FORMAT_FLAG_ALPHA)
#define PNG_FORMAT_ARGB (PNG_FORMAT_RGBA|PNG_FORMAT_FLAG_AFIRST)
#define PNG_FORMAT_BGRA (PNG_FORMAT_BGR|PNG_FORMAT_FLAG_ALPHA)
#define PNG_FORMAT_ABGR (PNG_FORMAT_BGRA|PNG_FORMAT_FLAG_AFIRST)
/* Then the linear 2-byte formats. When naming these "Y" is used to
* indicate a luminance (gray) channel.
*/
#define PNG_FORMAT_LINEAR_Y PNG_FORMAT_FLAG_LINEAR
#define PNG_FORMAT_LINEAR_Y_ALPHA (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_ALPHA)
#define PNG_FORMAT_LINEAR_RGB (PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR)
#define PNG_FORMAT_LINEAR_RGB_ALPHA \
(PNG_FORMAT_FLAG_LINEAR|PNG_FORMAT_FLAG_COLOR|PNG_FORMAT_FLAG_ALPHA)
/* With color-mapped formats the image data is one byte for each pixel, the byte
* is an index into the color-map which is formatted as above. To obtain a
* color-mapped format it is sufficient just to add the PNG_FOMAT_FLAG_COLORMAP
* to one of the above definitions, or you can use one of the definitions below.
*/
#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
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