view release on metacpan or  search on metacpan

src/Source/LibPNG/pngstruct.h  view on Meta::CPAN

/* pngstruct.h - header file for PNG reference library
 *
 * 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 1.6.1 [March 28, 2013]
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
 * and license in png.h
 */

/* The structure that holds the information to read and write PNG files.
 * The only people who need to care about what is inside of this are the
 * people who will be modifying the library for their own special needs.
 * It should NOT be accessed directly by an application.
 */

#ifndef PNGSTRUCT_H
#define PNGSTRUCT_H
/* zlib.h defines the structure z_stream, an instance of which is included
 * in this structure and is required for decompressing the LZ compressed
 * data in PNG files.
 */
#ifndef ZLIB_CONST
   /* We must ensure that zlib uses 'const' in declarations. */
#  define ZLIB_CONST
#endif
#include "zlib.h"
#ifdef const
   /* zlib.h sometimes #defines const to nothing, undo this. */
#  undef const
#endif

/* zlib.h has mediocre z_const use before 1.2.6, this stuff is for compatibility
 * with older builds.
 */
#if ZLIB_VERNUM < 0x1260
#  define PNGZ_MSG_CAST(s) png_constcast(char*,s)
#  define PNGZ_INPUT_CAST(b) png_constcast(png_bytep,b)
#else
#  define PNGZ_MSG_CAST(s) (s)
#  define PNGZ_INPUT_CAST(b) (b)
#endif

/* zlib.h declares a magic type 'uInt' that limits the amount of data that zlib
 * can handle at once.  This type need be no larger than 16 bits (so maximum of
 * 65535), this define allows us to discover how big it is, but limited by the
 * maximuum for png_size_t.  The value can be overriden in a library build
 * (pngusr.h, or set it in CPPFLAGS) and it works to set it to a considerably
 * lower value (e.g. 255 works).  A lower value may help memory usage (slightly)
 * and may even improve performance on some systems (and degrade it on others.)
 */
#ifndef ZLIB_IO_MAX
#  define ZLIB_IO_MAX ((uInt)-1)
#endif

#ifdef PNG_WRITE_SUPPORTED
/* The type of a compression buffer list used by the write code. */
typedef struct png_compression_buffer
{
   struct png_compression_buffer *next;
   png_byte                       output[1]; /* actually zbuf_size */
} png_compression_buffer, *png_compression_bufferp;

#define PNG_COMPRESSION_BUFFER_SIZE(pp)\
   (offsetof(png_compression_buffer, output) + (pp)->zbuffer_size)
#endif

/* Colorspace support; structures used in png_struct, png_info and in internal
 * functions to hold and communicate information about the color space.
 *
 * PNG_COLORSPACE_SUPPORTED is only required if the application will perform
 * colorspace corrections, otherwise all the colorspace information can be
 * skipped and the size of libpng can be reduced (significantly) by compiling
 * out the colorspace support.
 */
#ifdef PNG_COLORSPACE_SUPPORTED
/* The chromaticities of the red, green and blue colorants and the chromaticity
 * of the corresponding white point (i.e. of rgb(1.0,1.0,1.0)).
 */
typedef struct png_xy
{
   png_fixed_point redx, redy;
   png_fixed_point greenx, greeny;
   png_fixed_point bluex, bluey;
   png_fixed_point whitex, whitey;
} png_xy;

/* The same data as above but encoded as CIE XYZ values.  When this data comes
 * from chromaticities the sum of the Y values is assumed to be 1.0
 */
typedef struct png_XYZ
{
   png_fixed_point red_X, red_Y, red_Z;
   png_fixed_point green_X, green_Y, green_Z;
   png_fixed_point blue_X, blue_Y, blue_Z;
} png_XYZ;
#endif /* COLORSPACE */

#if defined(PNG_COLORSPACE_SUPPORTED) || defined(PNG_GAMMA_SUPPORTED)
/* A colorspace is all the above plus, potentially, profile information,
 * however at present libpng does not use the profile internally so it is only