png.h

hl2 source code. Do not use it illegal.

/* png.h - header file for PNG reference library
 *
 * libpng version 1.0.3 - January 14, 1999
 * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
 * Copyright (c) 1996, 1997 Andreas Dilger
 * Copyright (c) 1998, 1999 Glenn Randers-Pehrson
 *
 * Y2K compliance in libpng:
 * =========================
 *    
 *    January 13, 1999
 *    
 *    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 0.81 and
 *    upward are Y2K compliant.  It is my belief that earlier versions were
 *    also Y2K compliant.
 *    
 *    Libpng only has three year fields.  One is a 2-byte unsigned integer
 *    that will hold years up to 65535.  The other two hold the date in text
 *    format, and will hold years up to 9999.
 *    
 *    The integer is
 *        "png_uint_16 year" in png_time_struct.
 *    
 *    The strings are
 *        "png_charp time_buffer" in png_struct and
 *        "near_time_buffer", which is a local character string in png.c.
 *    
 *    There are seven time-related functions:
 *        png.c: png_convert_to_rfc_1123() in png.c 
 *          (formerly png_convert_to_rfc_1152() in error)
 *        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 applications using
 *    libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
 *    function, or 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.
 *    
 *    
 *       Glenn Randers-Pehrson
 *       libpng maintainer
 *       PNG Development Group
 * 
 * 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 [int should be 10000]
 *    1.0.0                     1.0.0      100  2.1.0 [int should be 10000]
 *    1.0.1                     1.0.1    10001  2.1.0
 *    1.0.1a-e                  1.0.1a-e 10002  2.1.0.1a-e
 *    1.0.2                     1.0.2    10002  2.1.0.2
 *    1.0.2a-c                  1.0.2a   10003  2.1.0.2a-c
 *    1.0.3                     1.0.3    10003  2.1.0.3
 *
 *    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).
 *
 * See libpng.txt or libpng.3 for more information.  The PNG specification
 * is available as RFC 2083 <ftp://ftp.uu.net/graphics/png/documents/>
 * and as a W3C Recommendation <http://www.w3.org/TR/REC.png.html>
 *
 * Contributing Authors:
 *    John Bowler
 *    Kevin Bracey
 *    Sam Bushell
 *    Andreas Dilger
 *    Magnus Holmgren
 *    Tom Lane
 *    Dave Martindale
 *    Glenn Randers-Pehrson
 *    Greg Roelofs
 *    Guy Eric Schalnat
 *    Paul Schmidt
 *    Tom Tanner
 *    Willem van Schaik
 *    Tim Wegner
 *
 * 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.
 *
 * COPYRIGHT NOTICE:
 *
 * The PNG Reference Library is supplied "AS IS".  The Contributing Authors
 * and Group 42, Inc. disclaim all warranties, expressed or implied,
 * including, without limitation, the warranties of merchantability and of
 * fitness for any purpose.  The Contributing Authors and Group 42, Inc.
 * assume no liability for direct, indirect, incidental, special, exemplary,
 * or consequential damages, which may result from the use of the PNG
 * Reference Library, even if advised of the possibility of such damage.
 *
 * Permission is hereby granted to use, copy, modify, and distribute this
 * source code, or portions hereof, for any purpose, without fee, subject
 * to the following restrictions:
 * 1. The origin of this source code must not be misrepresented.
 * 2. Altered versions must be plainly marked as such and must not be
 *    misrepresented as being the original source.
 * 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.
 */


#ifndef _PNG_H
#define _PNG_H

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

/* This is not the place to learn how to use libpng.  The file libpng.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.
 */

/* include the compression library's header */
#include "zlib.h"

/* include all user configurable info */
#include "pngconf.h"

/* This file is arranged in several sections.  The first section contains
 * structure and type definitions.  The second section contains the external
 * library functions, while the third has the internal library functions,
 * which applications aren't expected to use directly.
 */

/* Version information for png.h - this should match the version in png.c */
#define PNG_LIBPNG_VER_STRING "1.0.3"

/* 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=bugfix */
#define PNG_LIBPNG_VER    10003  /* 1.0.3 */

/* variables declared in png.c - only it needs to define PNG_NO_EXTERN */
#if !defined(PNG_NO_EXTERN) || defined(PNG_ALWAYS_EXTERN)
/* Version information for C files, stored in png.c.  This had better match
 * the version above.
 */
extern char png_libpng_ver[12];   /* need room for 99.99.99aa */

/* Structures to facilitate easy interlacing.  See png.c for more details */
extern int FARDATA png_pass_start[7];
extern int FARDATA png_pass_inc[7];
extern int FARDATA png_pass_ystart[7];
extern int FARDATA png_pass_yinc[7];
extern int FARDATA png_pass_mask[7];
extern int FARDATA png_pass_dsp_mask[7];
/* These aren't currently used.  If you need them, see png.c for more details
extern int FARDATA png_pass_width[7];
extern int FARDATA png_pass_height[7];
*/

#endif /* PNG_NO_EXTERN */

/* 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 FAR * png_colorp;
typedef png_color FAR * FAR * 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 FAR * png_color_16p;
typedef png_color_16 FAR * FAR * 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 FAR * png_color_8p;
typedef png_color_8 FAR * FAR * png_color_8pp;

/* png_text holds the text in a PNG file, and whether they are compressed
   in the PNG file or not.  The "text" field points to a regular C string. */
typedef struct png_text_struct
{
   int compression;        /* compression value, see PNG_TEXT_COMPRESSION_ */
   png_charp key;          /* keyword, 1-79 character description of "text" */
   png_charp text;         /* comment, may be an empty string (ie "") */
   png_size_t text_length; /* length of "text" field */
} png_text;
typedef png_text FAR * png_textp;
typedef png_text FAR * FAR * png_textpp;

/* 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_TEXT_COMPRESSION_LAST     1  /* 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 is 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 */