
/* png.h - header file for PNG reference library
 *
 * libpng version 1.5.25, December 3, 2015
 *
 * Copyright (c) 1998-2015 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 1.5.25, December 3, 2015:
 *     Glenn Randers-Pehrson.
 *   See also "Contributing Authors", below.
 */

/*
 * 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 1.0.7, July 1, 2000, through 1.5.25, December 3, 2015, are
 * Copyright (c) 2000-2002, 2004, 2006-2015 Glenn Randers-Pehrson, are
 * derived from libpng-1.0.6, 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
 *    Mans Rullgard
 *    Cosmin Truta
 *    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) 1998-2000 Glenn Randers-Pehrson, are derived from
 * libpng-0.96, 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, are derived from libpng-0.88,
 * and are 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
 *
 * 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.
 *
 * END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.
 */

/*
 * 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. OSI has not addressed
 * the additional disclaimers inserted at version 1.0.7.
 */

/*
 * 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.
 */

/* 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)
 *    1.0.5s-v                      10006 (not binary compatible)
 *    1.0.6 (+ 3 patches)           10006 (still binary incompatible)
 *    1.0.6d-f                      10007 (still binary incompatible)
 *    1.0.6g                        10007
 *    1.0.6h                        10007  10.6h (testing xy.z so-numbering)
 *    1.0.6i                        10007  10.6i
 *    1.0.6j                        10007  2.1.0.6j (incompatible with 1.0.0)
 *    1.0.7beta11-14        DLLNUM  10007  2.1.0.7beta11-14 (binary compatible)
 *    1.0.7beta15-18           1    10007  2.1.0.7beta15-18 (binary compatible)
 *    1.0.7rc1-2               1    10007  2.1.0.7rc1-2 (binary compatible)
 *    1.0.7                    1    10007  (still compatible)
 *    ...
 *    1.0.19                  10    10019  10.so.0.19[.0]
 *    ...
 *    1.2.53                  13    10253  12.so.0.53[.0]
 *    ...
 *    1.5.25                  15    10525  15.so.15.25[.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.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/
 */

/*
 * Y2K compliance in libpng:
 * =========================
 *
 *    December 3, 2015
 *
 *    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 1.5.25 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 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 will be no
 *    longer used in libpng-1.6.0 and will be removed from libpng-1.7.0.
 *
 *    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 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 "1.5.25"
#define PNG_HEADER_VERSION_STRING \
     " libpng version 1.5.25 - December 3, 2015\n"

#define PNG_LIBPNG_VER_SONUM   15
#define PNG_LIBPNG_VER_DLLNUM  15

/* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
#define PNG_LIBPNG_VER_MAJOR   1
#define PNG_LIBPNG_VER_MINOR   5
#define PNG_LIBPNG_VER_RELEASE 25

/* 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 10525 /* 1.5.25 */

/* 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
#  ifndef PNG_BUILDING_SYMBOL_TABLE
  /*
   *   Standard header files (not needed for the version info or while
   *   building symbol table -- see scripts/pnglibconf.dfa)
   */
#    ifdef PNG_SETJMP_SUPPORTED
#      include <setjmp.h>
#    endif

    /* Need the time information for converting tIME chunks, it
     * defines struct tm:
     */
#    ifdef PNG_CONVERT_tIME_SUPPORTED
       /* "time.h" functions are not supported on all operating systems */
#      include <time.h>
#    endif
#  endif

/* Machine specific configuration. */
#  include "pngconf.h"
#endif /* PNG_VERSION_INFO_ONLY */

/*
 * 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.
 *
 * 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_5_25;

/* 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_CONST png_color FAR * png_const_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_CONST png_color_16 FAR * png_const_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_CONST png_color_8 FAR * png_const_color_8p;
typedef png_color_8 FAR * FAR * 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 FAR * png_sPLT_entryp;
typedef PNG_CONST png_sPLT_entry FAR * png_const_sPLT_entryp;
typedef png_sPLT_entry FAR * FAR * 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 FAR * png_sPLT_tp;
typedef PNG_CONST png_sPLT_t FAR * png_const_sPLT_tp;
typedef png_sPLT_t FAR * FAR * 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 FAR * png_textp;
typedef PNG_CONST png_text FAR * png_const_textp;
typedef png_text FAR * FAR * 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 FAR * png_timep;
typedef PNG_CONST png_time FAR * png_const_timep;
typedef png_time FAR * FAR * png_timepp;

#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) || \
    defined(PNG_HANDLE_AS_UNKNOWN_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.
 */
typedef struct png_unknown_chunk_t
{
    png_byte name[5];
    png_byte *data;
    png_size_t size;

    /* libpng-using applications should NOT directly modify this byte. */
    png_byte location; /* mode of operation at read time */
}


png_unknown_chunk;
typedef png_unknown_chunk FAR * png_unknown_chunkp;
typedef PNG_CONST png_unknown_chunk FAR * png_const_unknown_chunkp;
typedef png_unknown_chunk FAR * FAR * png_unknown_chunkpp;
#endif

/* Values for the unknown chunk location byte */

#define PNG_HAVE_IHDR  0x01
#define PNG_HAVE_PLTE  0x02
#define PNG_AFTER_IDAT 0x08

/* The complete definition of png_info has, as of libpng-1.5.0,
 * 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 FAR * png_infop;
typedef PNG_CONST png_info FAR * png_const_infop;
typedef png_info FAR * FAR * png_infopp;

/* 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)
#define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA)
/* aliases */
#define PNG_COLOR_TYPE_RGBA  PNG_COLOR_TYPE_RGB_ALPHA
#define PNG_COLOR_TYPE_GA  PNG_COLOR_TYPE_GRAY_ALPHA

/* This is for compression type. PNG 1.0-1.2 only define the single type. */
#define PNG_COMPRESSION_TYPE_BASE 0 /* Deflate method 8, 32K window */
#define PNG_COMPRESSION_TYPE_DEFAULT PNG_COMPRESSION_TYPE_BASE

/* This is for filter type. PNG 1.0-1.2 only define the single type. */
#define PNG_FILTER_TYPE_BASE      0 /* Single row per-byte filtering */
#define PNG_INTRAPIXEL_DIFFERENCING 64 /* Used only in MNG datastreams */
#define PNG_FILTER_TYPE_DEFAULT   PNG_FILTER_TYPE_BASE

/* These are for the interlacing type.  These values should NOT be changed. */
#define PNG_INTERLACE_NONE        0 /* Non-interlaced image */
#define PNG_INTERLACE_ADAM7       1 /* Adam7 interlacing */
#define PNG_INTERLACE_LAST        2 /* Not a valid value */

/* These are for the oFFs chunk.  These values should NOT be changed. */
#define PNG_OFFSET_PIXEL          0 /* Offset in pixels */
#define PNG_OFFSET_MICROMETER     1 /* Offset in micrometers (1/10^6 meter) */
#define PNG_OFFSET_LAST           2 /* Not a valid value */

/* These are for the pCAL chunk.  These values should NOT be changed. */
#define PNG_EQUATION_LINEAR       0 /* Linear transformation */
#define PNG_EQUATION_BASE_E       1 /* Exponential base e transform */
#define PNG_EQUATION_ARBITRARY    2 /* Arbitrary base exponential transform */
#define PNG_EQUATION_HYPERBOLIC   3 /* Hyperbolic sine transformation */
#define PNG_EQUATION_LAST         4 /* Not a valid value */

/* These are for the sCAL chunk.  These values should NOT be changed. */
#define PNG_SCALE_UNKNOWN         0 /* unknown unit (image scale) */
#define PNG_SCALE_METER           1 /* meters per pixel */
#define PNG_SCALE_RADIAN          2 /* radians per pixel */
#define PNG_SCALE_LAST            3 /* Not a valid value */

/* These are for the pHYs chunk.  These values should NOT be changed. */
#define PNG_RESOLUTION_UNKNOWN    0 /* pixels/unknown unit (aspect ratio) */
#define PNG_RESOLUTION_METER      1 /* pixels/meter */
#define PNG_RESOLUTION_LAST       2 /* Not a valid value */

/* These are for the sRGB chunk.  These values should NOT be changed. */
#define PNG_sRGB_INTENT_PERCEPTUAL 0
#define PNG_sRGB_INTENT_RELATIVE   1
#define PNG_sRGB_INTENT_SATURATION 2
#define PNG_sRGB_INTENT_ABSOLUTE   3
#define PNG_sRGB_INTENT_LAST       4 /* Not a valid value */

/* This is for text chunks */
#define PNG_KEYWORD_MAX_LENGTH     79

/* Maximum number of entries in PLTE/sPLT/tRNS arrays */
#define PNG_MAX_PALETTE_LENGTH    256

/* These determine if an ancillary chunk's data has been successfully read
 * from the PNG header, or if the application has filled in the corresponding
 * data in the info_struct to be written into the output file.  The values
 * of the PNG_INFO_<chunk> defines should NOT be changed.
 */
#define PNG_INFO_gAMA 0x0001
#define PNG_INFO_sBIT 0x0002
#define PNG_INFO_cHRM 0x0004
#define PNG_INFO_PLTE 0x0008
#define PNG_INFO_tRNS 0x0010
#define PNG_INFO_bKGD 0x0020
#define PNG_INFO_hIST 0x0040
#define PNG_INFO_pHYs 0x0080
#define PNG_INFO_oFFs 0x0100
#define PNG_INFO_tIME 0x0200
#define PNG_INFO_pCAL 0x0400
#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 FAR * png_row_infop;
typedef png_row_info FAR * FAR * png_row_infopp;

/* The complete definition of png_struct has, as of libpng-1.5.0,
 * 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_struct_def png_struct;
typedef PNG_CONST png_struct FAR * png_const_structp;
typedef png_struct FAR * png_structp;

/* 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
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));

typedef png_struct FAR * FAR * png_structpp;

/* 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_structp 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);

#ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
PNG_EXPORT(6, png_size_t, png_get_compression_buffer_size,
    (png_const_structp png_ptr));

PNG_EXPORT(7, void, png_set_compression_buffer_size, (png_structp png_ptr,
    png_size_t size));
#endif /* WRITE_CUSTOMIZE_COMPRESSION */

/* 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_structp 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_structp png_ptr, int val),
    PNG_NORETURN);

#ifdef PNG_READ_SUPPORTED
/* Reset the compression stream */
PNG_EXPORT(10, int, png_reset_zstream, (png_structp png_ptr));
#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_structp png_ptr));

/* Write a PNG chunk - size, type, (optional) data, CRC. */
PNG_EXPORT(14, void, png_write_chunk, (png_structp 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_structp 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_structp 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_structp png_ptr));

/* Allocate and initialize the info structure */
PNG_EXPORTA(18, png_infop, png_create_info_struct, (png_structp png_ptr),
    PNG_ALLOCATED);

PNG_EXPORT(19, void, png_info_init_3, (png_infopp info_ptr,
    png_size_t png_info_struct_size));

/* Writes all the PNG information before the image. */
PNG_EXPORT(20, void, png_write_info_before_PLTE,
    (png_structp png_ptr, png_infop info_ptr));
PNG_EXPORT(21, void, png_write_info,
    (png_structp png_ptr, png_infop info_ptr));

#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read the information before the actual image data. */
PNG_EXPORT(22, void, png_read_info,
    (png_structp png_ptr, png_infop info_ptr));
#endif

#ifdef PNG_TIME_RFC1123_SUPPORTED
PNG_EXPORT(23, png_const_charp, png_convert_to_rfc1123,
    (png_structp png_ptr,
    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,
    PNG_CONST struct tm FAR * 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 /* PNG_CONVERT_tIME_SUPPORTED */

#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_structp png_ptr));
PNG_EXPORT(27, void, png_set_expand_gray_1_2_4_to_8, (png_structp png_ptr));
PNG_EXPORT(28, void, png_set_palette_to_rgb, (png_structp png_ptr));
PNG_EXPORT(29, void, png_set_tRNS_to_alpha, (png_structp 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_structp 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_structp 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_structp 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_structp png_ptr,
    int error_action, double red, double green))
PNG_FIXED_EXPORT(33, void, png_set_rgb_to_gray_fixed, (png_structp 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_structp
    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 when an alpha channel, or 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.
 *
 * The default is to return data according to the PNG specification: the alpha
 * channel is a linear measure of the contribution of the pixel to the
 * corresponding composited pixel.  The gamma encoded color channels must be
 * scaled according to the contribution and to do this it is necessary to undo
 * the encoding, scale the color values, perform the composition and reencode
 * the values.  This is the 'PNG' mode.
 *
 * The alternative is to 'associate' the alpha with the color information by
 * 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.  This is the 'STANDARD', 'ASSOCIATED' or 'PREMULTIPLIED' mode (the
 * latter being the two common names for associated alpha color channels.)
 *
 * 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.
 *
 * 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_structp png_ptr, int mode,
    double output_gamma))
PNG_FIXED_EXPORT(228, void, png_set_alpha_mode_fixed, (png_structp png_ptr,
    int mode, png_fixed_point output_gamma))
#endif

#if defined(PNG_READ_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.  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*.
 *
 * sRGB provides a peg for the PNG standard by defining a viewing environment.
 * sRGB itself, and earlier TV standards, actually use a more complex transform
 * (a linear portion then a gamma 2.4 power law) than PNG can express.  (PNG is
 * limited to simple power laws.)  By saying that an image for direct display on
 * an sRGB conformant system should be stored with a gAMA chunk value of 45455
 * (11.3.3.2 and 11.3.3.5 of the ISO PNG specification) the PNG specification
 * makes it possible to derive values for other display systems and
 * environments.
 *
 * 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 following values can be passed to either the fixed or floating
 * point APIs, but the floating point API will also accept floating point
 * values.
 */
#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_structp 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_structp 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_structp 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_structp 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_structp png_ptr, png_uint_32 filler,
    int flags));
#endif /* PNG_READ_FILLER_SUPPORTED || PNG_WRITE_FILLER_SUPPORTED */

#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_structp 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_structp 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_structp 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_structp 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_structp 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_structp 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_structp 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_structp 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_structp 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_structp 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_structp 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_structp png_ptr, double screen_gamma,
    double override_file_gamma))
PNG_FIXED_EXPORT(208, void, png_set_gamma_fixed, (png_structp 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_structp png_ptr, int nrows));
/* Flush the current PNG output buffer */
PNG_EXPORT(52, void, png_write_flush, (png_structp png_ptr));
#endif

/* Optional update palette with requested transformations */
PNG_EXPORT(53, void, png_start_read_image, (png_structp png_ptr));

/* Optional call to update the users info structure */
PNG_EXPORT(54, void, png_read_update_info,
    (png_structp png_ptr, png_infop info_ptr));

#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read one or more rows of image data. */
PNG_EXPORT(55, void, png_read_rows, (png_structp 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_structp 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_structp png_ptr, png_bytepp image));
#endif

/* Write a row of image data */
PNG_EXPORT(58, void, png_write_row,
    (png_structp 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_structp png_ptr, png_bytepp row,
    png_uint_32 num_rows));

/* Write the image data */
PNG_EXPORT(60, void, png_write_image,
    (png_structp png_ptr, png_bytepp image));

/* Write the end of the PNG file. */
PNG_EXPORT(61, void, png_write_end,
    (png_structp png_ptr, png_infop info_ptr));

#ifdef PNG_SEQUENTIAL_READ_SUPPORTED
/* Read the end of the PNG file. */
PNG_EXPORT(62, void, png_read_end, (png_structp png_ptr, png_infop info_ptr));
#endif

/* Free any memory associated with the png_info_struct */
PNG_EXPORT(63, void, png_destroy_info_struct, (png_structp 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_structp 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_structp 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 /* DEPRECATED */
PNG_FP_EXPORT(68, void, png_set_filter_heuristics, (png_structp 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_structp png_ptr,
    int heuristic_method, int num_weights, png_const_fixed_point_p
    filter_weights, png_const_fixed_point_p filter_costs))
#endif /*  PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */

/* The following are no longer used and will be removed from libpng-1.7: */
#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.
 */
#ifdef PNG_WRITE_CUSTOMIZE_COMPRESSION_SUPPORTED
PNG_EXPORT(69, void, png_set_compression_level,
    (png_structp png_ptr, int level));

PNG_EXPORT(70, void, png_set_compression_mem_level, (png_structp png_ptr,
    int mem_level));

PNG_EXPORT(71, void, png_set_compression_strategy, (png_structp 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_structp png_ptr,
    int window_bits));

PNG_EXPORT(73, void, png_set_compression_method, (png_structp png_ptr,
    int method));
#endif /* WRITE_CUSTOMIZE_COMPRESSION */

#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_structp png_ptr, int level));

PNG_EXPORT(223, void, png_set_text_compression_mem_level, (png_structp png_ptr,
    int mem_level));

PNG_EXPORT(224, void, png_set_text_compression_strategy, (png_structp 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_structp
    png_ptr, int window_bits));

PNG_EXPORT(226, void, png_set_text_compression_method, (png_structp png_ptr,
    int method));
#endif /* PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED */
#endif /* WRITE */

/* 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_structp 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_structp 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_structp 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_structp 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_structp 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_structp png_ptr));

PNG_EXPORT(80, void, png_set_read_status_fn, (png_structp png_ptr,
    png_read_status_ptr read_row_fn));

PNG_EXPORT(81, void, png_set_write_status_fn, (png_structp 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_structp 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_structp png_ptr));
#endif

#ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
PNG_EXPORT(84, void, png_set_read_user_transform_fn, (png_structp 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_structp 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_structp 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_structp 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_structp));
PNG_EXPORT(218, png_byte, png_get_current_pass_number, (png_const_structp));
#endif

#ifdef PNG_USER_CHUNKS_SUPPORTED
PNG_EXPORT(88, void, png_set_read_user_chunk_fn, (png_structp png_ptr,
    png_voidp user_chunk_ptr, png_user_chunk_ptr read_user_chunk_fn));
PNG_EXPORT(89, png_voidp, png_get_user_chunk_ptr, (png_const_structp 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_structp 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_structp png_ptr));

/* Function to be called when data becomes available */
PNG_EXPORT(92, void, png_process_data,
    (png_structp png_ptr, png_infop 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_structp, 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_structp));

#ifdef PNG_READ_INTERLACING_SUPPORTED
/* 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_structp png_ptr,
    png_bytep old_row, png_const_bytep new_row));
#endif /* PNG_READ_INTERLACING_SUPPORTED */
#endif /* PNG_PROGRESSIVE_READ_SUPPORTED */

PNG_EXPORTA(94, png_voidp, png_malloc,
    (png_structp png_ptr, png_alloc_size_t size),
    PNG_ALLOCATED);
/* Added at libpng version 1.4.0 */
PNG_EXPORTA(95, png_voidp, png_calloc,
    (png_structp 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_structp png_ptr,
    png_alloc_size_t size), PNG_ALLOCATED);

/* Frees a pointer allocated by png_malloc() */
PNG_EXPORT(97, void, png_free, (png_structp png_ptr, png_voidp ptr));

/* Free data that was allocated internally */
PNG_EXPORT(98, void, png_free_data,
    (png_structp png_ptr, png_infop info_ptr, png_uint_32 free_me, int num));

/* Reassign responsibility for freeing existing data, whether allocated
 * by libpng or by the application */
PNG_EXPORT(99, void, png_data_freer,
    (png_structp png_ptr, png_infop 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
#define PNG_FREE_UNKN 0x0200
#define PNG_FREE_LIST 0x0400
#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_structp png_ptr,
    png_alloc_size_t size), PNG_ALLOCATED);
PNG_EXPORT(101, void, png_free_default, (png_structp png_ptr, png_voidp ptr));
#endif

#ifdef PNG_ERROR_TEXT_SUPPORTED
/* Fatal error in PNG image of libpng - can't continue */
PNG_EXPORTA(102, void, png_error,
    (png_structp 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_structp 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_structp 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_structp 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_structp 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. */
#  undef png_benign_error
PNG_EXPORT(107, void, png_benign_error, (png_structp png_ptr,
    png_const_charp warning_message));

/* Same, chunk name is prepended to message. */
#  undef png_chunk_benign_error
PNG_EXPORT(108, void, png_chunk_benign_error, (png_structp png_ptr,
    png_const_charp warning_message));

PNG_EXPORT(109, void, png_set_benign_errors,
    (png_structp 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_structp png_ptr, png_const_infop 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_structp png_ptr,
    png_const_infop 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_structp png_ptr, png_const_infop 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_structp png_ptr,
    png_infop info_ptr, png_bytepp row_pointers));
#endif

/* Returns number of color channels in image. */
PNG_EXPORT(114, png_byte, png_get_channels,
    (png_const_structp png_ptr, png_const_infop info_ptr));

#ifdef PNG_EASY_ACCESS_SUPPORTED
/* Returns image width in pixels. */
PNG_EXPORT(115, png_uint_32, png_get_image_width, (png_const_structp png_ptr,
    png_const_infop info_ptr));

/* Returns image height in pixels. */
PNG_EXPORT(116, png_uint_32, png_get_image_height, (png_const_structp png_ptr,
    png_const_infop info_ptr));

/* Returns image bit_depth. */
PNG_EXPORT(117, png_byte, png_get_bit_depth,
    (png_const_structp png_ptr, png_const_infop info_ptr));

/* Returns image color_type. */
PNG_EXPORT(118, png_byte, png_get_color_type, (png_const_structp png_ptr,
    png_const_infop info_ptr));

/* Returns image filter_type. */
PNG_EXPORT(119, png_byte, png_get_filter_type, (png_const_structp png_ptr,
    png_const_infop info_ptr));

/* Returns image interlace_type. */
PNG_EXPORT(120, png_byte, png_get_interlace_type, (png_const_structp png_ptr,
    png_const_infop info_ptr));

/* Returns image compression_type. */
PNG_EXPORT(121, png_byte, png_get_compression_type, (png_const_structp png_ptr,
    png_const_infop 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_structp png_ptr, png_const_infop info_ptr));
PNG_EXPORT(123, png_uint_32, png_get_x_pixels_per_meter,
    (png_const_structp png_ptr, png_const_infop info_ptr));
PNG_EXPORT(124, png_uint_32, png_get_y_pixels_per_meter,
    (png_const_structp png_ptr, png_const_infop info_ptr));

/* Returns pixel aspect ratio, computed from pHYs chunk data.  */
PNG_FP_EXPORT(125, float, png_get_pixel_aspect_ratio,
    (png_const_structp png_ptr, png_const_infop info_ptr))
PNG_FIXED_EXPORT(210, png_fixed_point, png_get_pixel_aspect_ratio_fixed,
    (png_const_structp png_ptr, png_const_infop 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_structp png_ptr, png_const_infop info_ptr));
PNG_EXPORT(127, png_int_32, png_get_y_offset_pixels,
    (png_const_structp png_ptr, png_const_infop info_ptr));
PNG_EXPORT(128, png_int_32, png_get_x_offset_microns,
    (png_const_structp png_ptr, png_const_infop info_ptr));
PNG_EXPORT(129, png_int_32, png_get_y_offset_microns,
    (png_const_structp png_ptr, png_const_infop info_ptr));

#endif /* PNG_EASY_ACCESS_SUPPORTED */

/* Returns pointer to signature string read from PNG header */
PNG_EXPORT(130, png_const_bytep, png_get_signature,
    (png_const_structp png_ptr, png_infop info_ptr));

#ifdef PNG_bKGD_SUPPORTED
PNG_EXPORT(131, png_uint_32, png_get_bKGD,
    (png_const_structp png_ptr, png_infop info_ptr,
    png_color_16p *background));
#endif

#ifdef PNG_bKGD_SUPPORTED
PNG_EXPORT(132, void, png_set_bKGD, (png_structp png_ptr, png_infop info_ptr,
    png_const_color_16p background));
#endif

#ifdef PNG_cHRM_SUPPORTED
PNG_FP_EXPORT(133, png_uint_32, png_get_cHRM, (png_const_structp png_ptr,
   png_const_infop 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_structp png_ptr,
    png_const_infop 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))
#ifdef PNG_FIXED_POINT_SUPPORTED /* Otherwise not implemented */
PNG_FIXED_EXPORT(134, png_uint_32, png_get_cHRM_fixed,
    (png_const_structp png_ptr,
    png_const_infop 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))
#endif
PNG_FIXED_EXPORT(231, png_uint_32, png_get_cHRM_XYZ_fixed,
    (png_structp png_ptr, png_const_infop 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_structp png_ptr, png_infop 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_structp png_ptr,
    png_infop 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_structp png_ptr,
    png_infop 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_structp png_ptr,
    png_infop 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_structp png_ptr, png_const_infop info_ptr,
    double *file_gamma))
PNG_FIXED_EXPORT(138, png_uint_32, png_get_gAMA_fixed,
    (png_const_structp png_ptr, png_const_infop info_ptr,
    png_fixed_point *int_file_gamma))
#endif

#ifdef PNG_gAMA_SUPPORTED
PNG_FP_EXPORT(139, void, png_set_gAMA, (png_structp png_ptr,
    png_infop info_ptr, double file_gamma))
PNG_FIXED_EXPORT(140, void, png_set_gAMA_fixed, (png_structp png_ptr,
    png_infop info_ptr, png_fixed_point int_file_gamma))
#endif

#ifdef PNG_hIST_SUPPORTED
PNG_EXPORT(141, png_uint_32, png_get_hIST,
    (png_const_structp png_ptr, png_const_infop info_ptr,
    png_uint_16p *hist));
#endif

#ifdef PNG_hIST_SUPPORTED
PNG_EXPORT(142, void, png_set_hIST, (png_structp png_ptr,
    png_infop info_ptr, png_const_uint_16p hist));
#endif

PNG_EXPORT(143, png_uint_32, png_get_IHDR,
    (png_structp png_ptr, png_infop 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_structp png_ptr, png_infop 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_structp png_ptr, png_const_infop 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_structp png_ptr, png_infop 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_structp png_ptr, png_const_infop 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_structp png_ptr,
    png_infop 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_structp png_ptr, png_const_infop 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_structp png_ptr, png_infop 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_structp png_ptr, png_const_infop info_ptr,
    png_colorp *palette, int *num_palette));

PNG_EXPORT(152, void, png_set_PLTE,
    (png_structp png_ptr, png_infop info_ptr,
    png_const_colorp palette, int num_palette));

#ifdef PNG_sBIT_SUPPORTED
PNG_EXPORT(153, png_uint_32, png_get_sBIT,
    (png_const_structp png_ptr, png_infop info_ptr,
    png_color_8p *sig_bit));
#endif

#ifdef PNG_sBIT_SUPPORTED
PNG_EXPORT(154, void, png_set_sBIT,
    (png_structp png_ptr, png_infop info_ptr, png_const_color_8p sig_bit));
#endif

#ifdef PNG_sRGB_SUPPORTED
PNG_EXPORT(155, png_uint_32, png_get_sRGB, (png_const_structp png_ptr,
    png_const_infop info_ptr, int *file_srgb_intent));
#endif

#ifdef PNG_sRGB_SUPPORTED
PNG_EXPORT(156, void, png_set_sRGB,
    (png_structp png_ptr, png_infop info_ptr, int srgb_intent));
PNG_EXPORT(157, void, png_set_sRGB_gAMA_and_cHRM, (png_structp png_ptr,
    png_infop info_ptr, int srgb_intent));
#endif

#ifdef PNG_iCCP_SUPPORTED
PNG_EXPORT(158, png_uint_32, png_get_iCCP,
    (png_const_structp png_ptr, png_const_infop 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_structp png_ptr, png_infop 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, png_uint_32, png_get_sPLT,
    (png_const_structp png_ptr, png_const_infop info_ptr,
    png_sPLT_tpp entries));
#endif

#ifdef PNG_sPLT_SUPPORTED
PNG_EXPORT(161, void, png_set_sPLT,
    (png_structp png_ptr, png_infop 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, png_uint_32, png_get_text,
    (png_const_structp png_ptr, png_const_infop 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_structp png_ptr, png_infop 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_structp png_ptr, png_infop info_ptr, png_timep *mod_time));
#endif

#ifdef PNG_tIME_SUPPORTED
PNG_EXPORT(165, void, png_set_tIME,
    (png_structp png_ptr, png_infop info_ptr, png_const_timep mod_time));
#endif

#ifdef PNG_tRNS_SUPPORTED
PNG_EXPORT(166, png_uint_32, png_get_tRNS,
    (png_const_structp png_ptr, png_infop 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_structp png_ptr, png_infop 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_structp png_ptr, png_const_infop info_ptr,
    int *unit, double *width, double *height))
#ifdef PNG_FLOATING_ARITHMETIC_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_structp png_ptr, png_const_infop 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_structp png_ptr, png_const_infop info_ptr,
    int *unit, png_charpp swidth, png_charpp sheight));

PNG_FP_EXPORT(170, void, png_set_sCAL,
    (png_structp png_ptr, png_infop info_ptr,
    int unit, double width, double height))
PNG_FIXED_EXPORT(213, void, png_set_sCAL_fixed, (png_structp png_ptr,
   png_infop info_ptr, int unit, png_fixed_point width,
   png_fixed_point height))
PNG_EXPORT(171, void, png_set_sCAL_s,
    (png_structp png_ptr, png_infop info_ptr,
    int unit, png_const_charp swidth, png_const_charp sheight));
#endif /* PNG_sCAL_SUPPORTED */

#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
/* Provide a list of chunks and how they are to be handled, if the built-in
   handling or default unknown chunk handling is not desired.  Any chunks not
   listed will be handled in the default manner.  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!
      keep = 0: PNG_HANDLE_CHUNK_AS_DEFAULT: follow default behavior
           = 1: PNG_HANDLE_CHUNK_NEVER:      do not keep
           = 2: PNG_HANDLE_CHUNK_IF_SAFE:    keep only if safe-to-copy
           = 3: PNG_HANDLE_CHUNK_ALWAYS:     keep even if unsafe-to-copy
*/
PNG_EXPORT(172, void, png_set_keep_unknown_chunks,
    (png_structp png_ptr, int keep,
    png_const_bytep chunk_list, int num_chunks));

/* The handling code 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_structp png_ptr,
    png_const_bytep chunk_name));
#endif
#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED
PNG_EXPORT(174, void, png_set_unknown_chunks, (png_structp png_ptr,
    png_infop info_ptr, png_const_unknown_chunkp unknowns,
    int num_unknowns));
PNG_EXPORT(175, void, png_set_unknown_chunk_location,
    (png_structp png_ptr, png_infop info_ptr, int chunk, int location));
PNG_EXPORT(176, int, png_get_unknown_chunks, (png_const_structp png_ptr,
    png_const_infop 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_structp png_ptr, png_infop info_ptr, int mask));

#ifdef PNG_INFO_IMAGE_SUPPORTED
/* The "params" pointer is currently not used and is for future expansion. */
PNG_EXPORT(178, void, png_read_png, (png_structp png_ptr, png_infop info_ptr,
    int transforms, png_voidp params));
PNG_EXPORT(179, void, png_write_png, (png_structp png_ptr, png_infop info_ptr,
    int transforms, png_voidp params));
#endif

PNG_EXPORT(180, png_const_charp, png_get_copyright,
    (png_const_structp png_ptr));
PNG_EXPORT(181, png_const_charp, png_get_header_ver,
    (png_const_structp png_ptr));
PNG_EXPORT(182, png_const_charp, png_get_header_version,
    (png_const_structp png_ptr));
PNG_EXPORT(183, png_const_charp, png_get_libpng_ver,
    (png_const_structp png_ptr));

#ifdef PNG_MNG_FEATURES_SUPPORTED
PNG_EXPORT(184, png_uint_32, png_permit_mng_features, (png_structp 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

/* 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_structp 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_structp 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_structp png_ptr));
PNG_EXPORT(188, png_uint_32, png_get_user_height_max,
    (png_const_structp png_ptr));
/* Added in libpng-1.4.0 */
PNG_EXPORT(189, void, png_set_chunk_cache_max, (png_structp png_ptr,
    png_uint_32 user_chunk_cache_max));
PNG_EXPORT(190, png_uint_32, png_get_chunk_cache_max,
    (png_const_structp png_ptr));
/* Added in libpng-1.4.1 */
PNG_EXPORT(191, void, png_set_chunk_malloc_max, (png_structp png_ptr,
    png_alloc_size_t user_chunk_cache_max));
PNG_EXPORT(192, png_alloc_size_t, png_get_chunk_malloc_max,
    (png_const_structp png_ptr));
#endif

#if defined(PNG_INCH_CONVERSIONS_SUPPORTED)
PNG_EXPORT(193, png_uint_32, png_get_pixels_per_inch,
    (png_const_structp png_ptr, png_const_infop info_ptr));

PNG_EXPORT(194, png_uint_32, png_get_x_pixels_per_inch,
    (png_const_structp png_ptr, png_const_infop info_ptr));

PNG_EXPORT(195, png_uint_32, png_get_y_pixels_per_inch,
    (png_const_structp png_ptr, png_const_infop info_ptr));

PNG_FP_EXPORT(196, float, png_get_x_offset_inches,
    (png_const_structp png_ptr, png_const_infop info_ptr))
#ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
PNG_FIXED_EXPORT(211, png_fixed_point, png_get_x_offset_inches_fixed,
    (png_structp png_ptr, png_const_infop info_ptr))
#endif

PNG_FP_EXPORT(197, float, png_get_y_offset_inches, (png_const_structp png_ptr,
    png_const_infop info_ptr))
#ifdef PNG_FIXED_POINT_SUPPORTED /* otherwise not implemented. */
PNG_FIXED_EXPORT(212, png_fixed_point, png_get_y_offset_inches_fixed,
    (png_structp png_ptr, png_const_infop info_ptr))
#endif

#  ifdef PNG_pHYs_SUPPORTED
PNG_EXPORT(198, png_uint_32, png_get_pHYs_dpi, (png_const_structp png_ptr,
    png_const_infop info_ptr, png_uint_32 *res_x, png_uint_32 *res_y,
    int *unit_type));
#  endif /* PNG_pHYs_SUPPORTED */
#endif  /* PNG_INCH_CONVERSIONS_SUPPORTED */

/* Added in libpng-1.4.0 */
#ifdef PNG_IO_STATE_SUPPORTED
PNG_EXPORT(199, png_uint_32, png_get_io_state, (png_structp png_ptr));

PNG_EXPORTA(200, png_const_bytep, png_get_io_chunk_name,
    (png_structp png_ptr), PNG_DEPRECATED);
PNG_EXPORT(216, png_uint_32, png_get_io_chunk_type,
    (png_const_structp 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 /* ?PNG_IO_STATE_SUPPORTED */

/* 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)

/* A macro to return the offset between pixels in the output row for a pair of
 * pixels in the input - effectively the inverse of the 'COL_SHIFT' macro that
 * follows.  Note that ROW_OFFSET is the offset from one row to the next whereas
 * COL_OFFSET is from one column to the next, within a row.
 */
#define PNG_PASS_ROW_OFFSET(pass) ((pass)>2?(8>>(((pass)-1)>>1)):8)
#define PNG_PASS_COL_OFFSET(pass) (1<<((7-(pass))>>1))

/* Two macros to help evaluate the number of rows or columns in each
 * pass.  This is expressed as a shift - effectively log2 of the number or
 * rows or columns in each 8x8 tile of the original image.
 */
#define PNG_PASS_ROW_SHIFT(pass) ((pass)>2?(8-(pass))>>1:3)
#define PNG_PASS_COL_SHIFT(pass) ((pass)>1?(7-(pass))>>1:3)

/* Hence two macros to determine the number of rows or columns in a given
 * pass of an image given its height or width.  In fact these macros may
 * return non-zero even though the sub-image is empty, because the other
 * dimension may be empty for a small image.
 */
#define PNG_PASS_ROWS(height, pass) (((height)+(((1<<PNG_PASS_ROW_SHIFT(pass))\
   -1)-PNG_PASS_START_ROW(pass)))>>PNG_PASS_ROW_SHIFT(pass))
#define PNG_PASS_COLS(width, pass) (((width)+(((1<<PNG_PASS_COL_SHIFT(pass))\
   -1)-PNG_PASS_START_COL(pass)))>>PNG_PASS_COL_SHIFT(pass))

/* For the reader row callbacks (both progressive and sequential) it is
 * necessary to find the row in the output image given a row in an interlaced
 * image, so two more macros:
 */
#define PNG_ROW_FROM_PASS_ROW(yIn, pass) \
   (((yIn)<<PNG_PASS_ROW_SHIFT(pass))+PNG_PASS_START_ROW(pass))
#define PNG_COL_FROM_PASS_COL(xIn, pass) \
   (((xIn)<<PNG_PASS_COL_SHIFT(pass))+PNG_PASS_START_COL(pass))

/* Two macros which return a boolean (0 or 1) saying whether the given row
 * or column is in a particular pass.  These use a common utility macro that
 * returns a mask for a given pass - the offset 'off' selects the row or
 * column version.  The mask has the appropriate bit set for each column in
 * the tile.
 */
#define PNG_PASS_MASK(pass,off) ( \
   ((0x110145AF>>(((7-(off))-(pass))<<2)) & 0xF) | \
   ((0x01145AF0>>(((7-(off))-(pass))<<2)) & 0xF0))

#define PNG_ROW_IN_INTERLACE_PASS(y, pass) \
   ((PNG_PASS_MASK(pass,0) >> ((y)&7)) & 1)
#define PNG_COL_IN_INTERLACE_PASS(x, pass) \
   ((PNG_PASS_MASK(pass,1) >> ((x)&7)) & 1)

#ifdef PNG_READ_COMPOSITE_NODIV_SUPPORTED
/* With these routines we avoid an integer divide, which will be slower on
 * most machines.  However, it does take more operations than the corresponding
 * divide method, so it may be slower on a few RISC systems.  There are two
 * shifts (by 8 or 16 bits) and an addition, versus a single integer divide.
 *
 * 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 /* PNG_READ_COMPOSITE_NODIV_SUPPORTED */

#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_structp 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)^0xffffffffU)+1U)&0x7fffffffU)) \
      : (png_int_32)png_get_uint_32(buf)))
#endif

#ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
PNG_EXPORT(234, void, png_set_check_for_invalid_index, (png_structp png_ptr,
    int allowed));
#  ifdef PNG_GET_PALETTE_MAX_SUPPORTED
PNG_EXPORT(235, 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 */
#endif
#define PNG_OPTION_NEXT  2 /* 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(236, int, png_set_option, (png_structp png_ptr, int option,
   int onoff));
#endif

/*******************************************************************************
 *  END OF HARDWARE OPTIONS
 ******************************************************************************/

/* Maintainer: Put new public prototypes here ^, in libpng.3, and project
 * defs
 */

/* The last ordinal number (this is the *last* one already used; the next
 * one to use is one more than this.)  Maintainer, remember to add an entry to
 * scripts/symbols.def as well.
 */
#ifdef PNG_EXPORT_LAST_ORDINAL
  PNG_EXPORT_LAST_ORDINAL(236);
#endif

#ifdef __cplusplus
}
#endif

#endif /* PNG_VERSION_INFO_ONLY */
/* Do not put anything past this line */
#endif /* PNG_H */