/*
 * png.h - header file for PNG reference library
 * *
 * * libpng version 1.2.5 - October 3, 2002
 * * Copyright (c) 1998-2002 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.)
 * *
 * * 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 1.2.5 - October 3, 2002: Glenn
 * *  See also "Contributing Authors", below.
 * *
 * * Note about libpng version numbers:
 * *
 * *    Due to various miscommunications, unforeseen code incompatibilities
 * *    and occasional factors outside the authors' control, version numbering
 * *    on the library has not always been consistent and straightforward.
 * *    The following table summarizes matters since version 0.89c, which was
 * *    the first widely used release:
 * *
 * *    source                 png.h  png.h  shared-lib
 * *    version                string   int  version
 * *    -------                ------ -----  ----------
 * *    0.89c "1.0 beta 3"     0.89      89  1.0.89
 * *    0.90  "1.0 beta 4"     0.90      90  0.90  [should have been 2.0.90]
 * *    0.95  "1.0 beta 5"     0.95      95  0.95  [should have been 2.0.95]
 * *    0.96  "1.0 beta 6"     0.96      96  0.96  [should have been 2.0.96]
 * *    0.97b "1.00.97 beta 7" 1.00.97   97  1.0.1 [should have been 2.0.97]
 * *    0.97c                  0.97      97  2.0.97
 * *    0.98                   0.98      98  2.0.98
 * *    0.99                   0.99      98  2.0.99
 * *    0.99a-m                0.99      99  2.0.99
 * *    1.00                   1.00     100  2.1.0 [100 should be 10000]
 * *    1.0.0      (from here on, the   100  2.1.0 [100 should be 10000]
 * *    1.0.1       png.h string is   10001  2.1.0
 * *    1.0.1a-e    identical to the  10002  from here on, the shared library
 * *    1.0.2       source version)   10002  is 2.V where V is the source code
 * *    1.0.2a-b                      10003  version, except as noted.
 * *    1.0.3                         10003
 * *    1.0.3a-d                      10004
 * *    1.0.4                         10004
 * *    1.0.4a-f                      10005
 * *    1.0.5 (+ 2 patches)           10005
 * *    1.0.5a-d                      10006
 * *    1.0.5e-r                      10100 (not source compatible)
 * *    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)
 * *    1.0.8beta1-4             1    10008  2.1.0.8beta1-4
 * *    1.0.8rc1                 1    10008  2.1.0.8rc1
 * *    1.0.8                    1    10008  2.1.0.8
 * *    1.0.9beta1-6             1    10009  2.1.0.9beta1-6
 * *    1.0.9rc1                 1    10009  2.1.0.9rc1
 * *    1.0.9beta7-10            1    10009  2.1.0.9beta7-10
 * *    1.0.9rc2                 1    10009  2.1.0.9rc2
 * *    1.0.9                    1    10009  2.1.0.9
 * *    1.0.10beta1              1    10010  2.1.0.10beta1
 * *    1.0.10rc1                1    10010  2.1.0.10rc1
 * *    1.0.10                   1    10010  2.1.0.10
 * *    1.0.11beta1-3            1    10011  2.1.0.11beta1-3
 * *    1.0.11rc1                1    10011  2.1.0.11rc1
 * *    1.0.11                   1    10011  2.1.0.11
 * *    1.0.12beta1-2            2    10012  2.1.0.12beta1-2
 * *    1.0.12rc1                2    10012  2.1.0.12rc1
 * *    1.0.12                   2    10012  2.1.0.12
 * *    1.1.0a-f                 -    10100  2.1.1.0a-f (branch abandoned)
 * *    1.2.0beta1-2             2    10200  2.1.2.0beta1-2
 * *    1.2.0beta3-5             3    10200  3.1.2.0beta3-5
 * *    1.2.0rc1                 3    10200  3.1.2.0rc1
 * *    1.2.0                    3    10200  3.1.2.0
 * *    1.2.1beta1-4             3    10201  3.1.2.1beta1-4
 * *    1.2.1rc1-2               3    10201  3.1.2.1rc1-2
 * *    1.2.1                    3    10201  3.1.2.1
 * *    1.2.2beta1-6            12    10202  12.so.0.1.2.2beta1-6
 * *    1.0.13beta1             10    10013  10.so.0.1.0.13beta1
 * *    1.0.13rc1               10    10013  10.so.0.1.0.13rc1
 * *    1.2.2rc1                12    10202  12.so.0.1.2.2rc1
 * *    1.0.13                  10    10013  10.so.0.1.0.13
 * *    1.2.2                   12    10202  12.so.0.1.2.2
 * *    1.2.3rc1-6              12    10203  12.so.0.1.2.3rc1-6
 * *    1.2.3                   12    10203  12.so.0.1.2.3
 * *    1.2.4beta1-3            13    10204  12.so.0.1.2.4beta1-3
 * *    1.0.14rc1               13    10014  10.so.0.1.0.14rc1
 * *    1.2.4rc1                13    10204  12.so.0.1.2.4rc1
 * *    1.0.14                  10    10014  10.so.0.1.0.14
 * *    1.2.4                   13    10204  12.so.0.1.2.4
 * *    1.2.5beta1-2            13    10205  12.so.0.1.2.5beta1-2
 * *    1.0.15rc1-3             10    10015  10.so.0.1.0.15rc1-3
 * *    1.2.5rc1-3              13    10205  12.so.0.1.2.5rc1-3
 * *    1.0.15                  10    10015  10.so.0.1.0.15
 * *    1.2.5                   13    10205  12.so.0.1.2.5
 * *
 * *    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 "rcN".
 * *
 * *    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 RFC 2083 <ftp://ftp.uu.net/graphics/png/documents/>
 * * and as a W3C Recommendation <http://www.w3.org/TR/REC.png.html>
 */

/*
 * COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:
 *
 * If you modify libpng you may insert additional notices immediately following
 * this sentence.
 *
 * libpng versions 1.0.7, July 1, 2000, through 1.2.5, October 3, 2002, are
 * Copyright (c) 2000-2002 Glenn Randers-Pehrson, and are
 * distributed according to the same disclaimer and license as libpng-1.0.6
 * with the following individuals added to the list of Contributing Authors
 *
 *    Simon-Pierre Cadieux
 *    Eric S. Raymond
 *    Gilles Vollant
 *
 * and with the following additions to the disclaimer:
 *
 *    There is no warranty against interference with your enjoyment of the
 *    library or against infringement.  There is no warranty that our
 *    efforts or the library will fulfill any of your particular purposes
 *    or needs.  This library is provided with all faults, and the entire
 *    risk of satisfactory quality, performance, accuracy, and effort is with
 *    the user.
 *
 * libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are
 * Copyright (c) 1998, 1999, 2000 Glenn Randers-Pehrson
 * Distributed according to the same disclaimer and license as libpng-0.96,
 * with the following individuals added to the list of Contributing Authors:
 *
 *    Tom Lane
 *    Glenn Randers-Pehrson
 *    Willem van Schaik
 *
 * libpng versions 0.89, June 1996, through 0.96, May 1997, are
 * Copyright (c) 1996, 1997 Andreas Dilger
 * Distributed according to the same disclaimer and license as libpng-0.88,
 * with the following individuals added to the list of Contributing Authors:
 *
 *    John Bowler
 *    Kevin Bracey
 *    Sam Bushell
 *    Magnus Holmgren
 *    Greg Roelofs
 *    Tom Tanner
 *
 * libpng versions 0.5, May 1995, through 0.88, January 1996, are
 * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
 *
 * For the purposes of this copyright and license, "Contributing Authors"
 * is defined as the following set of individuals:
 *
 *    Andreas Dilger
 *    Dave Martindale
 *    Guy Eric Schalnat
 *    Paul Schmidt
 *    Tim Wegner
 *
 * 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.
 */

/*
 * A "png_get_copyright" function is available, for convenient use in "about"
 * boxes and the like:
 *
 * printf("%s",png_get_copyright(NULL));
 *
 * Also, the PNG logo (in PNG format, of course) is supplied in the
 * files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).
 */

/*
 * Libpng is OSI Certified Open Source Software.  OSI Certified is a
 * certification mark of the Open Source Initiative.
 */

/*
 * The contributing authors would like to thank all those who helped
 * with testing, bug fixes, and patience.  This wouldn't have been
 * possible without all of you.
 *
 * Thanks to Frank J. T. Wojcik for helping with the documentation.
 */

/*
 * Y2K compliance in libpng:
 *
 *
 *    October 3, 2002
 *
 *    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 1.2.5 are Y2K compliant.  It is my belief that earlier
 *    versions were also Y2K compliant.
 *
 *    Libpng only has three year fields.  One is a 2-byte unsigned integer
 *    that will hold years up to 65535.  The other two hold the date in text
 *    format, and will hold years up to 9999.
 *
 *    The integer is
 *        "png_uint_16 year" in png_time_struct.
 *
 *    The strings are
 *        "png_charp time_buffer" in png_struct and
 *        "near_time_buffer", which is a local character string in png.c.
 *
 *    There are seven time-related functions:
 *        png.c: png_convert_to_rfc_1123() in png.c
 *          (formerly png_convert_to_rfc_1152() in error)
 *        png_convert_from_struct_tm() in pngwrite.c, called in pngwrite.c
 *        png_convert_from_time_t() in pngwrite.c
 *        png_get_tIME() in pngget.c
 *        png_handle_tIME() in pngrutil.c, called in pngread.c
 *        png_set_tIME() in pngset.c
 *        png_write_tIME() in pngwutil.c, called in pngwrite.c
 *
 *    All handle dates properly in a Y2K environment.  The
 *    png_convert_from_time_t() function calls gmtime() to convert from system
 *    clock time, which returns (year - 1900), which we properly convert to
 *    the full 4-digit year.  There is a possibility that applications using
 *    libpng are not passing 4-digit years into the png_convert_to_rfc_1123()
 *    function, or 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.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.
 */

/*
 * Version information for png.h - this should match the version in png.c 
 */
#  define PNG_LIBPNG_VER_STRING "1.2.5"

#  define PNG_LIBPNG_VER_SONUM   0
#  define PNG_LIBPNG_VER_DLLNUM  %DLLNUM%

/*
 * These should match the first 3 components of PNG_LIBPNG_VER_STRING: 
 */
#  define PNG_LIBPNG_VER_MAJOR   1
#  define PNG_LIBPNG_VER_MINOR   2
#  define PNG_LIBPNG_VER_RELEASE 5
/*
 * 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

#  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_TYPEMASK 7
#  define PNG_LIBPNG_BUILD_PATCH    8  /* Can be OR'ed with STABLE only */
#  define PNG_LIBPNG_BUILD_TYPE 4

/*
 * 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 10205         /* 1.2.5 */

#  ifndef PNG_VERSION_INFO_ONLY

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

/*
 * include all user configurable info, including optional assembler routines 
 */
#    include "pngconf.h"

/*
 * Inhibit C++ name-mangling for libpng functions but not for system calls. 
 */
#    ifdef __cplusplus
extern        "C" {
#    endif                             /* __cplusplus */

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

#    ifndef PNG_NO_TYPECAST_NULL
#      define int_p_NULL                (int *)NULL
#      define png_bytep_NULL            (png_bytep)NULL
#      define png_bytepp_NULL           (png_bytepp)NULL
#      define png_doublep_NULL          (png_doublep)NULL
#      define png_error_ptr_NULL        (png_error_ptr)NULL
#      define png_flush_ptr_NULL        (png_flush_ptr)NULL
#      define png_free_ptr_NULL         (png_free_ptr)NULL
#      define png_infopp_NULL           (png_infopp)NULL
#      define png_malloc_ptr_NULL       (png_malloc_ptr)NULL
#      define png_read_status_ptr_NULL  (png_read_status_ptr)NULL
#      define png_rw_ptr_NULL           (png_rw_ptr)NULL
#      define png_structp_NULL          (png_structp)NULL
#      define png_uint_16p_NULL         (png_uint_16p)NULL
#      define png_voidp_NULL            (png_voidp)NULL
#      define png_write_status_ptr_NULL (png_write_status_ptr)NULL
#    else
#      define int_p_NULL                NULL
#      define png_bytep_NULL            NULL
#      define png_bytepp_NULL           NULL
#      define png_doublep_NULL          NULL
#      define png_error_ptr_NULL        NULL
#      define png_flush_ptr_NULL        NULL
#      define png_free_ptr_NULL         NULL
#      define png_infopp_NULL           NULL
#      define png_malloc_ptr_NULL       NULL
#      define png_read_status_ptr_NULL  NULL
#      define png_rw_ptr_NULL           NULL
#      define png_structp_NULL          NULL
#      define png_uint_16p_NULL         NULL
#      define png_voidp_NULL            NULL
#      define png_write_status_ptr_NULL NULL
#    endif

    /*
     * variables declared in png.c - only it needs to define PNG_NO_EXTERN 
     */
#    if !defined(PNG_NO_EXTERN) || defined(PNG_ALWAYS_EXTERN)
    /*
     * Version information for C files, stored in png.c.  This had better match
     * * the version above.
     */
#      ifdef PNG_USE_GLOBAL_ARRAYS
    PNG_EXPORT_VAR (const char) png_libpng_ver[18];
    /*
     * need room for 99.99.99beta99z 
     */
#      else
#        define png_libpng_ver png_get_header_ver(NULL)
#      endif

#      ifdef PNG_USE_GLOBAL_ARRAYS
    /*
     * This was removed in version 1.0.5c 
     */
    /*
     * Structures to facilitate easy interlacing.  See png.c for more details 
     */
                  PNG_EXPORT_VAR (const int FARDATA) png_pass_start[7];
                  PNG_EXPORT_VAR (const int FARDATA) png_pass_inc[7];
                  PNG_EXPORT_VAR (const int FARDATA) png_pass_ystart[7];
                  PNG_EXPORT_VAR (const int FARDATA) png_pass_yinc[7];
                  PNG_EXPORT_VAR (const int FARDATA) png_pass_mask[7];
                  PNG_EXPORT_VAR (const int FARDATA) png_pass_dsp_mask[7];
#        ifdef PNG_HAVE_ASSEMBLER_COMBINE_ROW
                  PNG_EXPORT_VAR (const int FARDATA) png_pass_width[7];
#        endif
    /*
     * This isn't currently used.  If you need it, see png.c for more details.
     * PNG_EXPORT_VAR (const int FARDATA) png_pass_height[7];
     */
#      endif

#    endif                             /* PNG_NO_EXTERN */

    /*
     * Three color definitions.  The order of the red, green, and blue, (and the
     * * exact size) is not important, although the size of the fields need to
     * * be png_byte or png_uint_16 (as defined below).
     */
    typedef struct png_color_struct {
        png_byte      red;
        png_byte      green;
        png_byte      blue;
    } png_color;
    typedef png_color FAR *png_colorp;
    typedef png_color FAR *FAR * png_colorpp;

    typedef struct png_color_16_struct {
        png_byte      index;           /* used for palette files */
        png_uint_16   red;             /* for use in red green blue files */
        png_uint_16   green;
        png_uint_16   blue;
        png_uint_16   gray;            /* for use in grayscale files */
    } png_color_16;
    typedef png_color_16 FAR *png_color_16p;
    typedef png_color_16 FAR *FAR * png_color_16pp;

    typedef struct png_color_8_struct {
        png_byte      red;             /* for use in red green blue files */
        png_byte      green;
        png_byte      blue;
        png_byte      gray;            /* for use in grayscale files */
        png_byte      alpha;           /* for alpha channel files */
    } png_color_8;
    typedef png_color_8 FAR *png_color_8p;
    typedef png_color_8 FAR *FAR * png_color_8pp;

    /*
     * 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_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_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", "lang", and
     * * "lang_key" fields can be regular C strings, empty strings, or NULL pointers.
     * * However, the * structure returned by png_get_text() will always contain
     * * regular zero-terminated C strings (possibly empty), never NULL pointers,
     * * so they can be safely used in printf() and other string-handling functions.
     */
    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 */
#      ifdef PNG_iTXt_SUPPORTED
        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 */
#      endif
    } png_text;
    typedef png_text FAR *png_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_time FAR *FAR * png_timepp;

#    if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
    /*
     * png_unknown_chunk is a structure to hold queued chunks for which there is
     * * no specific support.  The idea is that we can use this to queue
     * * up private chunks for output even though the library doesn't actually
     * * know about their semantics.
     */
    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_unknown_chunk FAR *FAR * png_unknown_chunkpp;
#    endif

    /*
     * png_info is a structure that holds the information in a PNG file so
     * * that the application can find out the characteristics of the image.
     * * If you are reading the file, this structure will tell you what is
     * * in the PNG file.  If you are writing the file, fill in the information
     * * you want to put into the PNG file, then call png_write_info().
     * * The names chosen should be very close to the PNG specification, so
     * * consult that document for information about the meaning of each field.
     * *
     * * With libpng < 0.95, it was only possible to directly set and read the
     * * the values in the png_info_struct, which meant that the contents and
     * * order of the values had to remain fixed.  With libpng 0.95 and later,
     * * however, there are now functions that abstract the contents of
     * * png_info_struct from the application, so this makes it easier to use
     * * libpng with dynamic libraries, and even makes it possible to use
     * * libraries that don't have all of the libpng ancillary chunk-handing
     * * functionality.
     * *
     * * In any case, the order of the parameters in png_info_struct should NOT
     * * be changed for as long as possible to keep compatibility with applications
     * * that use the old direct-access method with png_info_struct.
     * *
     * * The following members may have allocated storage attached that should be
     * * cleaned up before the structure is discarded: palette, trans, text,
     * * pcal_purpose, pcal_units, pcal_params, hist, iccp_name, iccp_profile,
     * * splt_palettes, scal_unit, row_pointers, and unknowns.   By default, these
     * * are automatically freed when the info structure is deallocated, if they were
     * * allocated internally by libpng.  This behavior can be changed by means
     * * of the png_data_freer() function.
     * *
     * * More allocation details: all the chunk-reading functions that
     * * change these members go through the corresponding png_set_*
     * * functions.  A function to clear these members is available: see
     * * png_free_data().  The png_set_* functions do not depend on being
     * * able to point info structure members to any of the storage they are
     * * passed (they make their own copies), EXCEPT that the png_set_text
     * * functions use the same storage passed to them in the text_ptr or
     * * itxt_ptr structure argument, and the png_set_rows and png_set_unknowns
     * * functions do not make their own copies.
     */
    typedef struct png_info_struct {
        /*
         * the following are necessary for every PNG file 
         */
        png_uint_32   width;           /* width of image in pixels (from IHDR) */
        png_uint_32   height;          /* height of image in pixels (from IHDR) */
        png_uint_32   valid;           /* valid chunk data (see PNG_INFO_ below) */
        png_uint_32   rowbytes;        /* bytes needed to hold an untransformed row */
        png_colorp    palette;         /* array of color values (valid & PNG_INFO_PLTE) */
        png_uint_16   num_palette;     /* number of color entries in "palette" (PLTE) */
        png_uint_16   num_trans;       /* number of transparent palette color (tRNS) */
        png_byte      bit_depth;       /* 1, 2, 4, 8, or 16 bits/channel (from IHDR) */
        png_byte      color_type;      /* see PNG_COLOR_TYPE_ below (from IHDR) */
        /*
         * The following three should have been named *_method not *_type 
         */
        png_byte      compression_type; /* must be PNG_COMPRESSION_TYPE_BASE (IHDR) */
        png_byte      filter_type;     /* must be PNG_FILTER_TYPE_BASE (from IHDR) */
        png_byte      interlace_type;  /* One of PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */

        /*
         * The following is informational only on read, and not used on writes. 
         */
        png_byte      channels;        /* number of data channels per pixel (1, 2, 3, 4) */
        png_byte      pixel_depth;     /* number of bits per pixel */
        png_byte      spare_byte;      /* to align the data, and for future use */
        png_byte      signature[8];    /* magic bytes read by libpng from start of file */

        /*
         * The rest of the data is optional.  If you are reading, check the
         * * valid field to see if the information in these are valid.  If you
         * * are writing, set the valid field to those chunks you want written,
         * * and initialize the appropriate fields below.
         */

#    if defined(PNG_gAMA_SUPPORTED) && defined(PNG_FLOATING_POINT_SUPPORTED)
        /*
         * The gAMA chunk describes the gamma characteristics of the system
         * * on which the image was created, normally in the range [1.0, 2.5].
         * * Data is valid if (valid & PNG_INFO_gAMA) is non-zero.
         */
        float         gamma;           /* gamma value of image, if (valid & PNG_INFO_gAMA) */
#    endif

#    if defined(PNG_sRGB_SUPPORTED)
        /*
         * GR-P, 0.96a 
         */
        /*
         * Data valid if (valid & PNG_INFO_sRGB) non-zero. 
         */
        png_byte      srgb_intent;     /* sRGB rendering intent [0, 1, 2, or 3] */
#    endif

#    if defined(PNG_TEXT_SUPPORTED)
        /*
         * The tEXt, and zTXt chunks contain human-readable textual data in
         * * uncompressed, compressed, and optionally compressed forms, respectively.
         * * The data in "text" is an array of pointers to uncompressed,
         * * null-terminated C strings. Each chunk has a keyword that describes the
         * * textual data contained in that chunk.  Keywords are not required to be
         * * unique, and the text string may be empty.  Any number of text chunks may
         * * be in an image.
         */
        int           num_text;        /* number of comments read/to write */
        int           max_text;        /* current size of text array */
        png_textp     text;            /* array of comments read/to write */
#    endif                             /* PNG_TEXT_SUPPORTED */

#    if defined(PNG_tIME_SUPPORTED)
        /*
         * The tIME chunk holds the last time the displayed image data was
         * * modified.  See the png_time struct for the contents of this struct.
         */
        png_time      mod_time;
#    endif

#    if defined(PNG_sBIT_SUPPORTED)
        /*
         * The sBIT chunk specifies the number of significant high-order bits
         * * in the pixel data.  Values are in the range [1, bit_depth], and are
         * * only specified for the channels in the pixel data.  The contents of
         * * the low-order bits is not specified.  Data is valid if
         * * (valid & PNG_INFO_sBIT) is non-zero.
         */
        png_color_8   sig_bit;         /* significant bits in color channels */
#    endif

#    if defined(PNG_tRNS_SUPPORTED) || defined(PNG_READ_EXPAND_SUPPORTED) || \
defined(PNG_READ_BACKGROUND_SUPPORTED)
        /*
         * The tRNS chunk supplies transparency data for paletted images and
         * * other image types that don't need a full alpha channel.  There are
         * * "num_trans" transparency values for a paletted image, stored in the
         * * same order as the palette colors, starting from index 0.  Values
         * * for the data are in the range [0, 255], ranging from fully transparent
         * * to fully opaque, respectively.  For non-paletted images, there is a
         * * single color specified that should be treated as fully transparent.
         * * Data is valid if (valid & PNG_INFO_tRNS) is non-zero.
         */
        png_bytep     trans;           /* transparent values for paletted image */
        png_color_16  trans_values;    /* transparent color for non-palette image */
#    endif

#    if defined(PNG_bKGD_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
        /*
         * The bKGD chunk gives the suggested image background color if the
         * * display program does not have its own background color and the image
         * * is needs to composited onto a background before display.  The colors
         * * in "background" are normally in the same color space/depth as the
         * * pixel data.  Data is valid if (valid & PNG_INFO_bKGD) is non-zero.
         */
        png_color_16  background;
#    endif

#    if defined(PNG_oFFs_SUPPORTED)
        /*
         * The oFFs chunk gives the offset in "offset_unit_type" units rightwards
         * * and downwards from the top-left corner of the display, page, or other
         * * application-specific co-ordinate space.  See the PNG_OFFSET_ defines
         * * below for the unit types.  Valid if (valid & PNG_INFO_oFFs) non-zero.
         */
        png_int_32    x_offset;        /* x offset on page */
        png_int_32    y_offset;        /* y offset on page */
        png_byte      offset_unit_type; /* offset units type */
#    endif

#    if defined(PNG_pHYs_SUPPORTED)
        /*
         * The pHYs chunk gives the physical pixel density of the image for
         * * display or printing in "phys_unit_type" units (see PNG_RESOLUTION_
         * * defines below).  Data is valid if (valid & PNG_INFO_pHYs) is non-zero.
         */
        png_uint_32   x_pixels_per_unit;        /* horizontal pixel density */
        png_uint_32   y_pixels_per_unit;        /* vertical pixel density */
        png_byte      phys_unit_type;  /* resolution type (see PNG_RESOLUTION_ below) */
#    endif

#    if defined(PNG_hIST_SUPPORTED)
        /*
         * The hIST chunk contains the relative frequency or importance of the
         * * various palette entries, so that a viewer can intelligently select a
         * * reduced-color palette, if required.  Data is an array of "num_palette"
         * * values in the range [0,65535]. Data valid if (valid & PNG_INFO_hIST)
         * * is non-zero.
         */
        png_uint_16p  hist;
#    endif

#    ifdef PNG_cHRM_SUPPORTED
        /*
         * The cHRM chunk describes the CIE color characteristics of the monitor
         * * on which the PNG was created.  This data allows the viewer to do gamut
         * * mapping of the input image to ensure that the viewer sees the same
         * * colors in the image as the creator.  Values are in the range
         * * [0.0, 0.8].  Data valid if (valid & PNG_INFO_cHRM) non-zero.
         */
#      ifdef PNG_FLOATING_POINT_SUPPORTED
        float         x_white;
        float         y_white;
        float         x_red;
        float         y_red;
        float         x_green;
        float         y_green;
        float         x_blue;
        float         y_blue;
#      endif
#    endif

#    if defined(PNG_pCAL_SUPPORTED)
        /*
         * The pCAL chunk describes a transformation between the stored pixel
         * * values and original physical data values used to create the image.
         * * The integer range [0, 2^bit_depth - 1] maps to the floating-point
         * * range given by [pcal_X0, pcal_X1], and are further transformed by a
         * * (possibly non-linear) transformation function given by "pcal_type"
         * * and "pcal_params" into "pcal_units".  Please see the PNG_EQUATION_
         * * defines below, and the PNG-Group's PNG extensions document for a
         * * complete description of the transformations and how they should be
         * * implemented, and for a description of the ASCII parameter strings.
         * * Data values are valid if (valid & PNG_INFO_pCAL) non-zero.
         */
        png_charp     pcal_purpose;    /* pCAL chunk description string */
        png_int_32    pcal_X0;         /* minimum value */
        png_int_32    pcal_X1;         /* maximum value */
        png_charp     pcal_units;      /* Latin-1 string giving physical units */
        png_charpp    pcal_params;     /* ASCII strings containing parameter values */
        png_byte      pcal_type;       /* equation type (see PNG_EQUATION_ below) */
        png_byte      pcal_nparams;    /* number of parameters given in pcal_params */
#    endif

        /*
         * New members added in libpng-1.0.6 
         */
#    ifdef PNG_FREE_ME_SUPPORTED
        png_uint_32   free_me;         /* flags items libpng is responsible for freeing */
#    endif

#    if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
        /*
         * storage for unknown chunks that the library doesn't recognize. 
         */
        png_unknown_chunkp unknown_chunks;
        png_size_t    unknown_chunks_num;
#    endif

#    if defined(PNG_iCCP_SUPPORTED)
        /*
         * iCCP chunk data. 
         */
        png_charp     iccp_name;       /* profile name */
        png_charp     iccp_profile;    /* International Color Consortium profile data */
        /*
         * Note to maintainer: should be png_bytep 
         */
        png_uint_32   iccp_proflen;    /* ICC profile data length */
        png_byte      iccp_compression; /* Always zero */
#    endif

#    if defined(PNG_sPLT_SUPPORTED)
        /*
         * data on sPLT chunks (there may be more than one). 
         */
        png_sPLT_tp   splt_palettes;
        png_uint_32   splt_palettes_num;
#    endif

#    if defined(PNG_sCAL_SUPPORTED)
        /*
         * The sCAL chunk describes the actual physical dimensions of the
         * * subject matter of the graphic.  The chunk contains a unit specification
         * * a byte value, and two ASCII strings representing floating-point
         * * values.  The values are width and height corresponsing to one pixel
         * * in the image.  This external representation is converted to double
         * * here.  Data values are valid if (valid & PNG_INFO_sCAL) is non-zero.
         */
        png_byte      scal_unit;       /* unit of physical scale */
#      ifdef PNG_FLOATING_POINT_SUPPORTED
        double        scal_pixel_width; /* width of one pixel */
        double        scal_pixel_height;        /* height of one pixel */
#      endif
#      ifdef PNG_FIXED_POINT_SUPPORTED
        png_charp     scal_s_width;    /* string containing height */
        png_charp     scal_s_height;   /* string containing width */
#      endif
#    endif

#    if defined(PNG_INFO_IMAGE_SUPPORTED)
        /*
         * Memory has been allocated if (valid & PNG_ALLOCATED_INFO_ROWS) non-zero 
         */
        /*
         * Data valid if (valid & PNG_INFO_IDAT) non-zero 
         */
        png_bytepp    row_pointers;    /* the image bits */
#    endif

#    if defined(PNG_FIXED_POINT_SUPPORTED) && defined(PNG_gAMA_SUPPORTED)
        png_fixed_point int_gamma;     /* gamma of image, if (valid & PNG_INFO_gAMA) */
#    endif

#    if defined(PNG_cHRM_SUPPORTED) && defined(PNG_FIXED_POINT_SUPPORTED)
        png_fixed_point int_x_white;
        png_fixed_point int_y_white;
        png_fixed_point int_x_red;
        png_fixed_point int_y_red;
        png_fixed_point int_x_green;
        png_fixed_point int_y_green;
        png_fixed_point int_x_blue;
        png_fixed_point int_y_blue;
#    endif

    } png_info;

    typedef png_info FAR *png_infop;
    typedef png_info FAR *FAR * png_infopp;

    /*
     * Maximum positive integer used in PNG is (2^31)-1 
     */
#    define PNG_MAX_UINT ((png_uint_32)0x7fffffffL)

    /*
     * 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 0x8000L      /* 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_uint_32   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;

    /*
     * 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.
     */
    typedef struct png_struct_def png_struct;
    typedef png_struct FAR *png_structp;

    typedef void  (PNGAPI * png_error_ptr) PNGARG ((png_structp, png_const_charp));
    typedef void  (PNGAPI * png_rw_ptr) PNGARG ((png_structp, png_bytep, png_size_t));
    typedef void  (PNGAPI * png_flush_ptr) PNGARG ((png_structp));
    typedef void  (PNGAPI * png_read_status_ptr) PNGARG ((png_structp, png_uint_32, int));
    typedef void  (PNGAPI * png_write_status_ptr) PNGARG ((png_structp, png_uint_32, int));

#    ifdef PNG_PROGRESSIVE_READ_SUPPORTED
    typedef void  (PNGAPI * png_progressive_info_ptr) PNGARG ((png_structp, png_infop));
    typedef void  (PNGAPI * png_progressive_end_ptr) PNGARG ((png_structp, png_infop));
    typedef void  (PNGAPI * png_progressive_row_ptr) PNGARG ((png_structp, png_bytep, png_uint_32, int));
#    endif

#    if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
    defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED) || \
    defined(PNG_LEGACY_SUPPORTED)
    typedef void  (PNGAPI * png_user_transform_ptr) PNGARG ((png_structp, png_row_infop, png_bytep));
#    endif

#    if defined(PNG_USER_CHUNKS_SUPPORTED)
    typedef int   (PNGAPI * png_user_chunk_ptr) PNGARG ((png_structp, png_unknown_chunkp));
#    endif
#    if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
    typedef void  (PNGAPI * png_unknown_chunk_ptr) PNGARG ((png_structp));
#    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 */

    /*
     * 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

    typedef       png_voidp (*png_malloc_ptr) PNGARG ((png_structp, png_size_t));
    typedef void  (*png_free_ptr) PNGARG ((png_structp, png_voidp));

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

    struct png_struct_def {
#    ifdef PNG_SETJMP_SUPPORTED
        jmp_buf       jmpbuf;          /* used in png_error */
#    endif
        png_error_ptr error_fn;        /* function for printing errors and aborting */
        png_error_ptr warning_fn;      /* function for printing warnings */
        png_voidp     error_ptr;       /* user supplied struct for error functions */
        png_rw_ptr    write_data_fn;   /* function for writing output data */
        png_rw_ptr    read_data_fn;    /* function for reading input data */
        png_voidp     io_ptr;          /* ptr to application struct for I/O functions */

#    if defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
        png_user_transform_ptr read_user_transform_fn;  /* user read transform */
#    endif

#    if defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
        png_user_transform_ptr write_user_transform_fn; /* user write transform */
#    endif

        /*
         * These were added in libpng-1.0.2 
         */
#    if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
#      if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
    defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
        png_voidp     user_transform_ptr;       /* user supplied struct for user transform */
        png_byte      user_transform_depth;     /* bit depth of user transformed pixels */
        png_byte      user_transform_channels;  /* channels in user transformed pixels */
#      endif
#    endif

        png_uint_32   mode;            /* tells us where we are in the PNG file */
        png_uint_32   flags;           /* flags indicating various things to libpng */
        png_uint_32   transformations; /* which transformations to perform */

        z_stream      zstream;         /* pointer to decompression structure (below) */
        png_bytep     zbuf;            /* buffer for zlib */
        png_size_t    zbuf_size;       /* size of zbuf */
        int           zlib_level;      /* holds zlib compression level */
        int           zlib_method;     /* holds zlib compression method */
        int           zlib_window_bits; /* holds zlib compression window bits */
        int           zlib_mem_level;  /* holds zlib compression memory level */
        int           zlib_strategy;   /* holds zlib compression strategy */

        png_uint_32   width;           /* width of image in pixels */
        png_uint_32   height;          /* height of image in pixels */
        png_uint_32   num_rows;        /* number of rows in current pass */
        png_uint_32   usr_width;       /* width of row at start of write */
        png_uint_32   rowbytes;        /* size of row in bytes */
        png_uint_32   irowbytes;       /* size of current interlaced row in bytes */
        png_uint_32   iwidth;          /* width of current interlaced row in pixels */
        png_uint_32   row_number;      /* current row in interlace pass */
        png_bytep     prev_row;        /* buffer to save previous (unfiltered) row */
        png_bytep     row_buf;         /* buffer to save current (unfiltered) row */
        png_bytep     sub_row;         /* buffer to save "sub" row when filtering */
        png_bytep     up_row;          /* buffer to save "up" row when filtering */
        png_bytep     avg_row;         /* buffer to save "avg" row when filtering */
        png_bytep     paeth_row;       /* buffer to save "Paeth" row when filtering */
        png_row_info  row_info;        /* used for transformation routines */

        png_uint_32   idat_size;       /* current IDAT size for read */
        png_uint_32   crc;             /* current chunk CRC value */
        png_colorp    palette;         /* palette from the input file */
        png_uint_16   num_palette;     /* number of color entries in palette */
        png_uint_16   num_trans;       /* number of transparency values */
        png_byte      chunk_name[5];   /* null-terminated name of current chunk */
        png_byte      compression;     /* file compression type (always 0) */
        png_byte      filter;          /* file filter type (always 0) */
        png_byte      interlaced;      /* PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */
        png_byte      pass;            /* current interlace pass (0 - 6) */
        png_byte      do_filter;       /* row filter flags (see PNG_FILTER_ below ) */
        png_byte      color_type;      /* color type of file */
        png_byte      bit_depth;       /* bit depth of file */
        png_byte      usr_bit_depth;   /* bit depth of users row */
        png_byte      pixel_depth;     /* number of bits per pixel */
        png_byte      channels;        /* number of channels in file */
        png_byte      usr_channels;    /* channels at start of write */
        png_byte      sig_bytes;       /* magic bytes read/written from start of file */

#    if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
#      ifdef PNG_LEGACY_SUPPORTED
        png_byte      filler;          /* filler byte for pixel expansion */
#      else
        png_uint_16   filler;          /* filler bytes for pixel expansion */
#      endif
#    endif

#    if defined(PNG_bKGD_SUPPORTED)
        png_byte      background_gamma_type;
#      ifdef PNG_FLOATING_POINT_SUPPORTED
        float         background_gamma;
#      endif
        png_color_16  background;      /* background color in screen gamma space */
#      if defined(PNG_READ_GAMMA_SUPPORTED)
        png_color_16  background_1;    /* background normalized to gamma 1.0 */
#      endif
#    endif                             /* PNG_bKGD_SUPPORTED */

#    if defined(PNG_WRITE_FLUSH_SUPPORTED)
        png_flush_ptr output_flush_fn; /* Function for flushing output */
        png_uint_32   flush_dist;      /* how many rows apart to flush, 0 - no flush */
        png_uint_32   flush_rows;      /* number of rows written since last flush */
#    endif

#    if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
        int           gamma_shift;     /* number of "insignificant" bits 16-bit gamma */
#      ifdef PNG_FLOATING_POINT_SUPPORTED
        float         gamma;           /* file gamma value */
        float         screen_gamma;    /* screen gamma value (display_exponent) */
#      endif
#    endif

#    if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
        png_bytep     gamma_table;     /* gamma table for 8-bit depth files */
        png_bytep     gamma_from_1;    /* converts from 1.0 to screen */
        png_bytep     gamma_to_1;      /* converts from file to 1.0 */
        png_uint_16pp gamma_16_table;  /* gamma table for 16-bit depth files */
        png_uint_16pp gamma_16_from_1; /* converts from 1.0 to screen */
        png_uint_16pp gamma_16_to_1;   /* converts from file to 1.0 */
#    endif

#    if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_sBIT_SUPPORTED)
        png_color_8   sig_bit;         /* significant bits in each available channel */
#    endif

#    if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
        png_color_8   shift;           /* shift for significant bit tranformation */
#    endif

#    if defined(PNG_tRNS_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) \
 || defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
        png_bytep     trans;           /* transparency values for paletted files */
        png_color_16  trans_values;    /* transparency values for non-paletted files */
#    endif

        png_read_status_ptr read_row_fn;        /* called after each row is decoded */
        png_write_status_ptr write_row_fn;      /* called after each row is encoded */
#    ifdef PNG_PROGRESSIVE_READ_SUPPORTED
        png_progressive_info_ptr info_fn;       /* called after header data fully read */
        png_progressive_row_ptr row_fn; /* called after each prog. row is decoded */
        png_progressive_end_ptr end_fn; /* called after image is complete */
        png_bytep     save_buffer_ptr; /* current location in save_buffer */
        png_bytep     save_buffer;     /* buffer for previously read data */
        png_bytep     current_buffer_ptr;       /* current location in current_buffer */
        png_bytep     current_buffer;  /* buffer for recently used data */
        png_uint_32   push_length;     /* size of current input chunk */
        png_uint_32   skip_length;     /* bytes to skip in input data */
        png_size_t    save_buffer_size; /* amount of data now in save_buffer */
        png_size_t    save_buffer_max; /* total size of save_buffer */
        png_size_t    buffer_size;     /* total amount of available input data */
        png_size_t    current_buffer_size;      /* amount of data now in current_buffer */
        int           process_mode;    /* what push library is currently doing */
        int           cur_palette;     /* current push library palette index */

#      if defined(PNG_TEXT_SUPPORTED)
        png_size_t    current_text_size;        /* current size of text input data */
        png_size_t    current_text_left;        /* how much text left to read in input */
        png_charp     current_text;    /* current text chunk buffer */
        png_charp     current_text_ptr; /* current location in current_text */
#      endif                           /* PNG_PROGRESSIVE_READ_SUPPORTED && PNG_TEXT_SUPPORTED */

#    endif                             /* PNG_PROGRESSIVE_READ_SUPPORTED */

#    if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__)
        /*
         * for the Borland special 64K segment handler 
         */
        png_bytepp    offset_table_ptr;
        png_bytep     offset_table;
        png_uint_16   offset_table_number;
        png_uint_16   offset_table_count;
        png_uint_16   offset_table_count_free;
#    endif

#    if defined(PNG_READ_DITHER_SUPPORTED)
        png_bytep     palette_lookup;  /* lookup table for dithering */
        png_bytep     dither_index;    /* index translation for palette files */
#    endif

#    if defined(PNG_READ_DITHER_SUPPORTED) || defined(PNG_hIST_SUPPORTED)
        png_uint_16p  hist;            /* histogram */
#    endif

#    if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
        png_byte      heuristic_method; /* heuristic for row filter selection */
        png_byte      num_prev_filters; /* number of weights for previous rows */
        png_bytep     prev_filters;    /* filter type(s) of previous row(s) */
        png_uint_16p  filter_weights;  /* weight(s) for previous line(s) */
        png_uint_16p  inv_filter_weights;       /* 1/weight(s) for previous line(s) */
        png_uint_16p  filter_costs;    /* relative filter calculation cost */
        png_uint_16p  inv_filter_costs; /* 1/relative filter calculation cost */
#    endif

#    if defined(PNG_TIME_RFC1123_SUPPORTED)
        png_charp     time_buffer;     /* String to hold RFC 1123 time text */
#    endif

        /*
         * New members added in libpng-1.0.6 
         */

#    ifdef PNG_FREE_ME_SUPPORTED
        png_uint_32   free_me;         /* flags items libpng is responsible for freeing */
#    endif

#    if defined(PNG_USER_CHUNKS_SUPPORTED)
        png_voidp     user_chunk_ptr;
        png_user_chunk_ptr read_user_chunk_fn;  /* user read chunk handler */
#    endif

#    if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
        int           num_chunk_list;
        png_bytep     chunk_list;
#    endif

        /*
         * New members added in libpng-1.0.3 
         */
#    if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
        png_byte      rgb_to_gray_status;
        /*
         * These were changed from png_byte in libpng-1.0.6 
         */
        png_uint_16   rgb_to_gray_red_coeff;
        png_uint_16   rgb_to_gray_green_coeff;
        png_uint_16   rgb_to_gray_blue_coeff;
#    endif

        /*
         * New member added in libpng-1.0.4 (renamed in 1.0.9) 
         */
#    if defined(PNG_MNG_FEATURES_SUPPORTED) || \
    defined(PNG_READ_EMPTY_PLTE_SUPPORTED) || \
    defined(PNG_WRITE_EMPTY_PLTE_SUPPORTED)
        /*
         * changed from png_byte to png_uint_32 at version 1.2.0 
         */
#      ifdef PNG_1_0_X
        png_byte      mng_features_permitted;
#      else
        png_uint_32   mng_features_permitted;
#      endif                           /* PNG_1_0_X */
#    endif

        /*
         * New member added in libpng-1.0.7 
         */
#    if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
        png_fixed_point int_gamma;
#    endif

        /*
         * New member added in libpng-1.0.9, ifdef'ed out in 1.0.12, enabled in 1.2.0 
         */
#    if defined(PNG_MNG_FEATURES_SUPPORTED)
        png_byte      filter_type;
#    endif

#    if defined(PNG_1_0_X) || (defined(PNG_DEBUG) && defined(PNG_USE_PNGGCCRD))
        /*
         * New member added in libpng-1.0.10, ifdef'ed out in 1.2.0 
         */
        png_uint_32   row_buf_size;
#    endif

        /*
         * New members added in libpng-1.2.0 
         */
#    if !defined(PNG_1_0_X) && defined(PNG_ASSEMBLER_CODE_SUPPORTED)
        png_byte      mmx_bitdepth_threshold;
        png_uint_32   mmx_rowbytes_threshold;
        png_uint_32   asm_flags;
#    endif

        /*
         * New members added in libpng-1.0.2 but first enabled by default in 1.2.0 
         */
#    ifdef PNG_USER_MEM_SUPPORTED
        png_voidp     mem_ptr;         /* user supplied struct for mem functions */
        png_malloc_ptr malloc_fn;      /* function for allocating memory */
        png_free_ptr  free_fn;         /* function for freeing memory */
#    endif

        /*
         * New member added in libpng-1.0.13 and 1.2.0 
         */
        png_bytep     big_row_buf;     /* buffer to save current (unfiltered) row */

#    if defined(PNG_READ_DITHER_SUPPORTED)
        /*
         * The following three members were added at version 1.0.14 and 1.2.4 
         */
        png_bytep     dither_sort;     /* working sort array */
        png_bytep     index_to_palette; /* where the original index currently is */
        /*
         * in the palette 
         */
        png_bytep     palette_to_index; /* which original index points to this */
        /*
         * palette color 
         */
#    endif

    };

    /*
     * This prevents a compiler error in png.c if png.c and png.h are both at
     * version 1.2.5
     */
    typedef png_structp version_1_2_5;

    typedef png_struct FAR *FAR * png_structpp;

    /*
     * Here are the function definitions most commonly used.  This is not
     * * the place to find out how to use libpng.  See libpng.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.
     */

    /*
     * Returns the version number of the library 
     */
    extern        PNG_EXPORT (png_uint_32, png_access_version_number) PNGARG ((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.
     */
    extern        PNG_EXPORT (void, png_set_sig_bytes) PNGARG ((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).
     */
    extern        PNG_EXPORT (int, png_sig_cmp) PNGARG ((png_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).
     */
    extern        PNG_EXPORT (int, png_check_sig) PNGARG ((png_bytep sig, int num));

    /*
     * Allocate and initialize png_ptr struct for reading, and any other memory. 
     */
    extern        PNG_EXPORT (png_structp, png_create_read_struct)
                 
        PNGARG ((png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warn_fn));

    /*
     * Allocate and initialize png_ptr struct for writing, and any other memory 
     */
    extern        PNG_EXPORT (png_structp, png_create_write_struct)
                 
        PNGARG ((png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn, png_error_ptr warn_fn));

    extern        PNG_EXPORT (png_uint_32, png_get_compression_buffer_size)
                  PNGARG ((png_structp png_ptr));

    extern        PNG_EXPORT (void, png_set_compression_buffer_size)
                  PNGARG ((png_structp png_ptr, png_uint_32 size));

    /*
     * Reset the compression stream 
     */
    extern        PNG_EXPORT (int, png_reset_zstream) PNGARG ((png_structp png_ptr));

    /*
     * New functions added in libpng-1.0.2 (not enabled by default until 1.2.0) 
     */
#    ifdef PNG_USER_MEM_SUPPORTED
    extern        PNG_EXPORT (png_structp, png_create_read_struct_2)
                 
        PNGARG ((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));
    extern        PNG_EXPORT (png_structp, png_create_write_struct_2)
                 
        PNGARG ((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));
#    endif

    /*
     * Write a PNG chunk - size, type, (optional) data, CRC. 
     */
    extern        PNG_EXPORT (void,
                              png_write_chunk) PNGARG ((png_structp png_ptr, png_bytep chunk_name, png_bytep data,
                                                        png_size_t length));

    /*
     * Write the start of a PNG chunk - length and chunk name. 
     */
    extern        PNG_EXPORT (void,
                              png_write_chunk_start) PNGARG ((png_structp png_ptr, png_bytep chunk_name,
                                                              png_uint_32 length));

    /*
     * Write the data of a PNG chunk started with png_write_chunk_start(). 
     */
    extern        PNG_EXPORT (void,
                              png_write_chunk_data) PNGARG ((png_structp png_ptr, png_bytep data, png_size_t length));

    /*
     * Finish a chunk started with png_write_chunk_start() (includes CRC). 
     */
    extern        PNG_EXPORT (void, png_write_chunk_end) PNGARG ((png_structp png_ptr));

    /*
     * Allocate and initialize the info structure 
     */
    extern        PNG_EXPORT (png_infop, png_create_info_struct)
                  PNGARG ((png_structp png_ptr));

    /*
     * Initialize the info structure (old interface - DEPRECATED) 
     */
    extern        PNG_EXPORT (void, png_info_init) PNGARG ((png_infop info_ptr));
#    undef png_info_init
#    define png_info_init(info_ptr) png_info_init_3(&info_ptr, sizeof(png_info));
    extern        PNG_EXPORT (void, png_info_init_3) PNGARG ((png_infopp info_ptr, png_size_t png_info_struct_size));

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

    /*
     * read the information before the actual image data. 
     */
    extern        PNG_EXPORT (void, png_read_info) PNGARG ((png_structp png_ptr, png_infop info_ptr));

#    if defined(PNG_TIME_RFC1123_SUPPORTED)
    extern        PNG_EXPORT (png_charp, png_convert_to_rfc1123)
                  PNGARG ((png_structp png_ptr, png_timep ptime));
#    endif

#    if !defined(_WIN32_WCE)
    /*
     * "time.h" functions are not supported on WindowsCE 
     */
#      if defined(PNG_WRITE_tIME_SUPPORTED)
    /*
     * convert from a struct tm to png_time 
     */
    extern        PNG_EXPORT (void, png_convert_from_struct_tm) PNGARG ((png_timep ptime, struct tm FAR * ttime));

    /*
     * convert from time_t to png_time.  Uses gmtime() 
     */
    extern        PNG_EXPORT (void, png_convert_from_time_t) PNGARG ((png_timep ptime, time_t ttime));
#      endif                           /* PNG_WRITE_tIME_SUPPORTED */
#    endif                             /* _WIN32_WCE */

#    if defined(PNG_READ_EXPAND_SUPPORTED)
    /*
     * Expand data to 24-bit RGB, or 8-bit grayscale, with alpha if available. 
     */
    extern        PNG_EXPORT (void, png_set_expand) PNGARG ((png_structp png_ptr));
    extern        PNG_EXPORT (void, png_set_gray_1_2_4_to_8) PNGARG ((png_structp png_ptr));
    extern        PNG_EXPORT (void, png_set_palette_to_rgb) PNGARG ((png_structp png_ptr));
    extern        PNG_EXPORT (void, png_set_tRNS_to_alpha) PNGARG ((png_structp png_ptr));
#    endif

#    if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
    /*
     * Use blue, green, red order for pixels. 
     */
    extern        PNG_EXPORT (void, png_set_bgr) PNGARG ((png_structp png_ptr));
#    endif

#    if defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
    /*
     * Expand the grayscale to 24-bit RGB if necessary. 
     */
    extern        PNG_EXPORT (void, png_set_gray_to_rgb) PNGARG ((png_structp png_ptr));
#    endif

#    if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
    /*
     * Reduce RGB to grayscale. 
     */
#      ifdef PNG_FLOATING_POINT_SUPPORTED
    extern        PNG_EXPORT (void,
                              png_set_rgb_to_gray) PNGARG ((png_structp png_ptr, int error_action, double red,
                                                            double green));
#      endif
    extern        PNG_EXPORT (void,
                              png_set_rgb_to_gray_fixed) PNGARG ((png_structp png_ptr, int error_action,
                                                                  png_fixed_point red, png_fixed_point green));
    extern        PNG_EXPORT (png_byte, png_get_rgb_to_gray_status) PNGARG ((png_structp png_ptr));
#    endif

    extern        PNG_EXPORT (void, png_build_grayscale_palette) PNGARG ((int bit_depth, png_colorp palette));

#    if defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
    extern        PNG_EXPORT (void, png_set_strip_alpha) PNGARG ((png_structp png_ptr));
#    endif

#    if defined(PNG_READ_SWAP_ALPHA_SUPPORTED) || \
    defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
    extern        PNG_EXPORT (void, png_set_swap_alpha) PNGARG ((png_structp png_ptr));
#    endif

#    if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) || \
    defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
    extern        PNG_EXPORT (void, png_set_invert_alpha) PNGARG ((png_structp png_ptr));
#    endif

#    if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
    /*
     * Add a filler byte to 24-bit RGB images. 
     */
    extern        PNG_EXPORT (void, png_set_filler) PNGARG ((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
#    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. 
     */
    extern        PNG_EXPORT (void, png_set_swap) PNGARG ((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. 
     */
    extern        PNG_EXPORT (void, png_set_packing) PNGARG ((png_structp png_ptr));
#    endif

#    if defined(PNG_READ_PACKSWAP_SUPPORTED) || defined(PNG_WRITE_PACKSWAP_SUPPORTED)
    /*
     * Swap packing order of pixels in bytes. 
     */
    extern        PNG_EXPORT (void, png_set_packswap) PNGARG ((png_structp png_ptr));
#    endif

#    if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
    /*
     * Converts files to legal bit depths. 
     */
    extern        PNG_EXPORT (void, png_set_shift) PNGARG ((png_structp png_ptr, png_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. 
     */
    extern        PNG_EXPORT (int, png_set_interlace_handling) PNGARG ((png_structp png_ptr));
#    endif

#    if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
    /*
     * Invert monochrome files 
     */
    extern        PNG_EXPORT (void, png_set_invert_mono) PNGARG ((png_structp png_ptr));
#    endif

#    if defined(PNG_READ_BACKGROUND_SUPPORTED)
    /*
     * Handle alpha and tRNS by replacing with a background color. 
     */
#      ifdef PNG_FLOATING_POINT_SUPPORTED
    extern        PNG_EXPORT (void,
                              png_set_background) PNGARG ((png_structp png_ptr, png_color_16p background_color,
                                                           int background_gamma_code, int need_expand,
                                                           double background_gamma));
#      endif
#      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

#    if defined(PNG_READ_16_TO_8_SUPPORTED)
    /*
     * strip the second byte of information from a 16-bit depth file. 
     */
    extern        PNG_EXPORT (void, png_set_strip_16) PNGARG ((png_structp png_ptr));
#    endif

#    if defined(PNG_READ_DITHER_SUPPORTED)
    /*
     * Turn on dithering, and reduce the palette to the number of colors available. 
     */
    extern        PNG_EXPORT (void,
                              png_set_dither) PNGARG ((png_structp png_ptr, png_colorp palette, int num_palette,
                                                       int maximum_colors, png_uint_16p histogram, int full_dither));
#    endif

#    if defined(PNG_READ_GAMMA_SUPPORTED)
    /*
     * Handle gamma correction. Screen_gamma=(display_exponent) 
     */
#      ifdef PNG_FLOATING_POINT_SUPPORTED
    extern        PNG_EXPORT (void,
                              png_set_gamma) PNGARG ((png_structp png_ptr, double screen_gamma,
                                                      double default_file_gamma));
#      endif
#    endif

#    if defined(PNG_READ_EMPTY_PLTE_SUPPORTED) || \
    defined(PNG_WRITE_EMPTY_PLTE_SUPPORTED)
    /*
     * Permit or disallow empty PLTE (0: not permitted, 1: permitted) 
     */
    /*
     * Deprecated and will be removed.  Use png_permit_mng_features() instead. 
     */
    extern        PNG_EXPORT (void, png_permit_empty_plte) PNGARG ((png_structp png_ptr, int empty_plte_permitted));
#    endif

#    if defined(PNG_WRITE_FLUSH_SUPPORTED)
    /*
     * Set how many lines between output flushes - 0 for no flushing 
     */
    extern        PNG_EXPORT (void, png_set_flush) PNGARG ((png_structp png_ptr, int nrows));
    /*
     * Flush the current PNG output buffer 
     */
    extern        PNG_EXPORT (void, png_write_flush) PNGARG ((png_structp png_ptr));
#    endif

    /*
     * optional update palette with requested transformations 
     */
    extern        PNG_EXPORT (void, png_start_read_image) PNGARG ((png_structp png_ptr));

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

    /*
     * read one or more rows of image data. 
     */
    extern        PNG_EXPORT (void,
                              png_read_rows) PNGARG ((png_structp png_ptr, png_bytepp row, png_bytepp display_row,
                                                      png_uint_32 num_rows));

    /*
     * read a row of data. 
     */
    extern        PNG_EXPORT (void, png_read_row) PNGARG ((png_structp png_ptr, png_bytep row, png_bytep display_row));

    /*
     * read the whole image into memory at once. 
     */
    extern        PNG_EXPORT (void, png_read_image) PNGARG ((png_structp png_ptr, png_bytepp image));

    /*
     * write a row of image data 
     */
    extern        PNG_EXPORT (void, png_write_row) PNGARG ((png_structp png_ptr, png_bytep row));

    /*
     * write a few rows of image data 
     */
    extern        PNG_EXPORT (void,
                              png_write_rows) PNGARG ((png_structp png_ptr, png_bytepp row, png_uint_32 num_rows));

    /*
     * write the image data 
     */
    extern        PNG_EXPORT (void, png_write_image) PNGARG ((png_structp png_ptr, png_bytepp image));

    /*
     * writes the end of the PNG file. 
     */
    extern        PNG_EXPORT (void, png_write_end) PNGARG ((png_structp png_ptr, png_infop info_ptr));

    /*
     * read the end of the PNG file. 
     */
    extern        PNG_EXPORT (void, png_read_end) PNGARG ((png_structp png_ptr, png_infop info_ptr));

    /*
     * free any memory associated with the png_info_struct 
     */
    extern        PNG_EXPORT (void, png_destroy_info_struct) PNGARG ((png_structp png_ptr, png_infopp info_ptr_ptr));

    /*
     * free any memory associated with the png_struct and the png_info_structs 
     */
    extern        PNG_EXPORT (void,
                              png_destroy_read_struct) PNGARG ((png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
                                                                png_infopp end_info_ptr_ptr));

    /*
     * free all memory used by the read (old method - NOT DLL EXPORTED) 
     */
    extern void png_read_destroy PNGARG ((png_structp png_ptr, png_infop info_ptr, png_infop end_info_ptr));

    /*
     * free any memory associated with the png_struct and the png_info_structs 
     */
    extern        PNG_EXPORT (void, png_destroy_write_struct)
                  PNGARG ((png_structpp png_ptr_ptr, png_infopp info_ptr_ptr));

    /*
     * free any memory used in png_ptr struct (old method - NOT DLL EXPORTED) 
     */
    extern void png_write_destroy PNGARG ((png_structp png_ptr));

    /*
     * set the libpng method of handling chunk CRC errors 
     */
    extern        PNG_EXPORT (void,
                              png_set_crc_action) PNGARG ((png_structp png_ptr, int crit_action, int ancil_action));

    /*
     * Values for png_set_crc_action() to 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.
     */
    extern        PNG_EXPORT (void, png_set_filter) PNGARG ((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

#    if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)    /* EXPERIMENTAL */
    /*
     * The "heuristic_method" is given by one of the PNG_FILTER_HEURISTIC_
     * * defines, either the default (minimum-sum-of-absolute-differences), or
     * * the experimental method (weighted-minimum-sum-of-absolute-differences).
     * *
     * * Weights are factors >= 1.0, indicating how important it is to keep the
     * * filter type consistent between rows.  Larger numbers mean the current
     * * filter is that many times as likely to be the same as the "num_weights"
     * * previous filters.  This is cumulative for each previous row with a weight.
     * * There needs to be "num_weights" values in "filter_weights", or it can be
     * * NULL if the weights aren't being specified.  Weights have no influence on
     * * the selection of the first row filter.  Well chosen weights can (in theory)
     * * improve the compression for a given image.
     * *
     * * Costs are factors >= 1.0 indicating the relative decoding costs of a
     * * filter type.  Higher costs indicate more decoding expense, and are
     * * therefore less likely to be selected over a filter with lower computational
     * * costs.  There needs to be a value in "filter_costs" for each valid filter
     * * type (given by PNG_FILTER_VALUE_LAST), or it can be NULL if you aren't
     * * setting the costs.  Costs try to improve the speed of decompression without
     * * unduly increasing the compressed image size.
     * *
     * * A negative weight or cost indicates the default value is to be used, and
     * * values in the range [0.0, 1.0) indicate the value is to remain unchanged.
     * * The default values for both weights and costs are currently 1.0, but may
     * * change if good general weighting/cost heuristics can be found.  If both
     * * the weights and costs are set to 1.0, this degenerates the WEIGHTED method
     * * to the UNWEIGHTED method, but with added encoding time/computation.
     */
#      ifdef PNG_FLOATING_POINT_SUPPORTED
    extern        PNG_EXPORT (void,
                              png_set_filter_heuristics) PNGARG ((png_structp png_ptr, int heuristic_method,
                                                                  int num_weights, png_doublep filter_weights,
                                                                  png_doublep filter_costs));
#      endif
#    endif                             /*  PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */

    /*
     * Heuristic used for row filter selection.  These defines should NOT be
     * * changed.
     */
#    define PNG_FILTER_HEURISTIC_DEFAULT    0   /* Currently "UNWEIGHTED" */
#    define PNG_FILTER_HEURISTIC_UNWEIGHTED 1   /* Used by libpng < 0.95 */
#    define PNG_FILTER_HEURISTIC_WEIGHTED   2   /* Experimental feature */
#    define PNG_FILTER_HEURISTIC_LAST       3   /* Not a valid value */

    /*
     * 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.
     */
    extern        PNG_EXPORT (void, png_set_compression_level) PNGARG ((png_structp png_ptr, int level));

    extern        PNG_EXPORT (void, png_set_compression_mem_level)
                  PNGARG ((png_structp png_ptr, int mem_level));

    extern        PNG_EXPORT (void, png_set_compression_strategy)
                  PNGARG ((png_structp png_ptr, int strategy));

    extern        PNG_EXPORT (void, png_set_compression_window_bits)
                  PNGARG ((png_structp png_ptr, int window_bits));

    extern        PNG_EXPORT (void, png_set_compression_method) PNGARG ((png_structp png_ptr, int method));

    /*
     * 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.txt for
     * * more information.
     */

#    if !defined(PNG_NO_STDIO)
    /*
     * Initialize the input/output for the PNG file to the default functions. 
     */
    extern        PNG_EXPORT (void, png_init_io) PNGARG ((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.
     */

    extern        PNG_EXPORT (void,
                              png_set_error_fn) PNGARG ((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 
     */
    extern        PNG_EXPORT (png_voidp, png_get_error_ptr) PNGARG ((png_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).
     */
    extern        PNG_EXPORT (void,
                              png_set_write_fn) PNGARG ((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. 
     */
    extern        PNG_EXPORT (void,
                              png_set_read_fn) PNGARG ((png_structp png_ptr, png_voidp io_ptr,
                                                        png_rw_ptr read_data_fn));

    /*
     * Return the user pointer associated with the I/O functions 
     */
    extern        PNG_EXPORT (png_voidp, png_get_io_ptr) PNGARG ((png_structp png_ptr));

    extern        PNG_EXPORT (void,
                              png_set_read_status_fn) PNGARG ((png_structp png_ptr, png_read_status_ptr read_row_fn));

    extern        PNG_EXPORT (void,
                              png_set_write_status_fn) PNGARG ((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). 
     */
    extern        PNG_EXPORT (void,
                              png_set_mem_fn) PNGARG ((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 
     */
    extern        PNG_EXPORT (png_voidp, png_get_mem_ptr) PNGARG ((png_structp png_ptr));
#    endif

#    if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
    defined(PNG_LEGACY_SUPPORTED)
    extern        PNG_EXPORT (void,
                              png_set_read_user_transform_fn) PNGARG ((png_structp png_ptr,
                                                                       png_user_transform_ptr read_user_transform_fn));
#    endif

#    if defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED) || \
    defined(PNG_LEGACY_SUPPORTED)
    extern        PNG_EXPORT (void,
                              png_set_write_user_transform_fn) PNGARG ((png_structp png_ptr,
                                                                        png_user_transform_ptr
                                                                        write_user_transform_fn));
#    endif

#    if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
    defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED) || \
    defined(PNG_LEGACY_SUPPORTED)
    extern        PNG_EXPORT (void,
                              png_set_user_transform_info) PNGARG ((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 
     */
    extern        PNG_EXPORT (png_voidp, png_get_user_transform_ptr)
                  PNGARG ((png_structp png_ptr));
#    endif

#    ifdef PNG_USER_CHUNKS_SUPPORTED
    extern        PNG_EXPORT (void,
                              png_set_read_user_chunk_fn) PNGARG ((png_structp png_ptr, png_voidp user_chunk_ptr,
                                                                   png_user_chunk_ptr read_user_chunk_fn));
    extern        PNG_EXPORT (png_voidp, png_get_user_chunk_ptr) PNGARG ((png_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.
     */
    extern        PNG_EXPORT (void,
                              png_set_progressive_read_fn) PNGARG ((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 
     */
    extern        PNG_EXPORT (png_voidp, png_get_progressive_ptr)
                  PNGARG ((png_structp png_ptr));

    /*
     * function to be called when data becomes available 
     */
    extern        PNG_EXPORT (void,
                              png_process_data) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_bytep buffer,
                                                         png_size_t buffer_size));

    /*
     * function that combines rows.  Not very much different than the
     * * png_combine_row() call.  Is this even used?????
     */
    extern        PNG_EXPORT (void,
                              png_progressive_combine_row) PNGARG ((png_structp png_ptr, png_bytep old_row,
                                                                    png_bytep new_row));
#    endif                             /* PNG_PROGRESSIVE_READ_SUPPORTED */

    extern        PNG_EXPORT (png_voidp, png_malloc) PNGARG ((png_structp png_ptr, png_uint_32 size));

#    if defined(PNG_1_0_X)
#      define png_malloc_warn png_malloc
#    else
    /*
     * Added at libpng version 1.2.4 
     */
    extern        PNG_EXPORT (png_voidp, png_malloc_warn) PNGARG ((png_structp png_ptr, png_uint_32 size));
#    endif

    /*
     * frees a pointer allocated by png_malloc() 
     */
    extern        PNG_EXPORT (void, png_free) PNGARG ((png_structp png_ptr, png_voidp ptr));

#    if defined(PNG_1_0_X)
    /*
     * Function to allocate memory for zlib. 
     */
    extern        PNG_EXPORT (voidpf, png_zalloc) PNGARG ((voidpf png_ptr, uInt items, uInt size));

    /*
     * Function to free memory for zlib 
     */
    extern        PNG_EXPORT (void, png_zfree) PNGARG ((voidpf png_ptr, voidpf ptr));
#    endif

    /*
     * Free data that was allocated internally 
     */
    extern        PNG_EXPORT (void,
                              png_free_data) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 free_me,
                                                      int num));
#    ifdef PNG_FREE_ME_SUPPORTED
    /*
     * Reassign responsibility for freeing existing data, whether allocated
     * * by libpng or by the application 
     */
    extern        PNG_EXPORT (void,
                              png_data_freer) PNGARG ((png_structp png_ptr, png_infop info_ptr, int freer,
                                                       png_uint_32 mask));
#    endif
    /*
     * 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
    extern        PNG_EXPORT (png_voidp, png_malloc_default) PNGARG ((png_structp png_ptr, png_uint_32 size));
    extern        PNG_EXPORT (void, png_free_default) PNGARG ((png_structp png_ptr, png_voidp ptr));
#    endif

    extern        PNG_EXPORT (png_voidp,
                              png_memcpy_check) PNGARG ((png_structp png_ptr, png_voidp s1, png_voidp s2,
                                                         png_uint_32 size));

    extern        PNG_EXPORT (png_voidp,
                              png_memset_check) PNGARG ((png_structp png_ptr, png_voidp s1, int value,
                                                         png_uint_32 size));

#    if defined(USE_FAR_KEYWORD)       /* memory model conversion function */
    extern void  *png_far_to_near PNGARG ((png_structp png_ptr, png_voidp ptr, int check));
#    endif                             /* USE_FAR_KEYWORD */

    /*
     * Fatal error in PNG image of libpng - can't continue 
     */
    extern        PNG_EXPORT (void, png_error) PNGARG ((png_structp png_ptr, png_const_charp error_message));

    /*
     * The same, but the chunk name is prepended to the error string. 
     */
    extern        PNG_EXPORT (void, png_chunk_error) PNGARG ((png_structp png_ptr, png_const_charp error_message));

    /*
     * Non-fatal error in libpng.  Can continue, but may have a problem. 
     */
    extern        PNG_EXPORT (void, png_warning) PNGARG ((png_structp png_ptr, png_const_charp warning_message));

    /*
     * Non-fatal error in libpng, chunk name is prepended to message. 
     */
    extern        PNG_EXPORT (void, png_chunk_warning) PNGARG ((png_structp png_ptr, png_const_charp warning_message));

    /*
     * 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. 
     */
    extern        PNG_EXPORT (png_uint_32,
                              png_get_valid) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 flag));

    /*
     * Returns number of bytes needed to hold a transformed row. 
     */
    extern        PNG_EXPORT (png_uint_32, png_get_rowbytes) PNGARG ((png_structp png_ptr, png_infop info_ptr));

#    if defined(PNG_INFO_IMAGE_SUPPORTED)
    /*
     * Returns row_pointers, which is an array of pointers to scanlines that was
     * returned from png_read_png(). 
     */
    extern        PNG_EXPORT (png_bytepp, png_get_rows) PNGARG ((png_structp png_ptr, png_infop info_ptr));
    /*
     * Set row_pointers, which is an array of pointers to scanlines for use
     * by png_write_png(). 
     */
    extern        PNG_EXPORT (void,
                              png_set_rows) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_bytepp row_pointers));
#    endif

    /*
     * Returns number of color channels in image. 
     */
    extern        PNG_EXPORT (png_byte, png_get_channels) PNGARG ((png_structp png_ptr, png_infop info_ptr));

#    ifdef PNG_EASY_ACCESS_SUPPORTED
    /*
     * Returns image width in pixels. 
     */
    extern        PNG_EXPORT (png_uint_32, png_get_image_width) PNGARG ((png_structp png_ptr, png_infop info_ptr));

    /*
     * Returns image height in pixels. 
     */
    extern        PNG_EXPORT (png_uint_32, png_get_image_height) PNGARG ((png_structp png_ptr, png_infop info_ptr));

    /*
     * Returns image bit_depth. 
     */
    extern        PNG_EXPORT (png_byte, png_get_bit_depth) PNGARG ((png_structp png_ptr, png_infop info_ptr));

    /*
     * Returns image color_type. 
     */
    extern        PNG_EXPORT (png_byte, png_get_color_type) PNGARG ((png_structp png_ptr, png_infop info_ptr));

    /*
     * Returns image filter_type. 
     */
    extern        PNG_EXPORT (png_byte, png_get_filter_type) PNGARG ((png_structp png_ptr, png_infop info_ptr));

    /*
     * Returns image interlace_type. 
     */
    extern        PNG_EXPORT (png_byte, png_get_interlace_type) PNGARG ((png_structp png_ptr, png_infop info_ptr));

    /*
     * Returns image compression_type. 
     */
    extern        PNG_EXPORT (png_byte, png_get_compression_type) PNGARG ((png_structp png_ptr, png_infop info_ptr));

    /*
     * Returns image resolution in pixels per meter, from pHYs chunk data. 
     */
    extern        PNG_EXPORT (png_uint_32, png_get_pixels_per_meter) PNGARG ((png_structp png_ptr, png_infop info_ptr));
    extern        PNG_EXPORT (png_uint_32,
                              png_get_x_pixels_per_meter) PNGARG ((png_structp png_ptr, png_infop info_ptr));
    extern        PNG_EXPORT (png_uint_32,
                              png_get_y_pixels_per_meter) PNGARG ((png_structp png_ptr, png_infop info_ptr));

    /*
     * Returns pixel aspect ratio, computed from pHYs chunk data.  
     */
#      ifdef PNG_FLOATING_POINT_SUPPORTED
    extern        PNG_EXPORT (float, png_get_pixel_aspect_ratio) PNGARG ((png_structp png_ptr, png_infop info_ptr));
#      endif

    /*
     * Returns image x, y offset in pixels or microns, from oFFs chunk data. 
     */
    extern        PNG_EXPORT (png_int_32, png_get_x_offset_pixels) PNGARG ((png_structp png_ptr, png_infop info_ptr));
    extern        PNG_EXPORT (png_int_32, png_get_y_offset_pixels) PNGARG ((png_structp png_ptr, png_infop info_ptr));
    extern        PNG_EXPORT (png_int_32, png_get_x_offset_microns) PNGARG ((png_structp png_ptr, png_infop info_ptr));
    extern        PNG_EXPORT (png_int_32, png_get_y_offset_microns) PNGARG ((png_structp png_ptr, png_infop info_ptr));

#    endif                             /* PNG_EASY_ACCESS_SUPPORTED */

    /*
     * Returns pointer to signature string read from PNG header 
     */
    extern        PNG_EXPORT (png_bytep, png_get_signature) PNGARG ((png_structp png_ptr, png_infop info_ptr));

#    if defined(PNG_bKGD_SUPPORTED)
    extern        PNG_EXPORT (png_uint_32,
                              png_get_bKGD) PNGARG ((png_structp png_ptr, png_infop info_ptr,
                                                     png_color_16p * background));
#    endif

#    if defined(PNG_bKGD_SUPPORTED)
    extern        PNG_EXPORT (void,
                              png_set_bKGD) PNGARG ((png_structp png_ptr, png_infop info_ptr,
                                                     png_color_16p background));
#    endif

#    if defined(PNG_cHRM_SUPPORTED)
#      ifdef PNG_FLOATING_POINT_SUPPORTED
    extern        PNG_EXPORT (png_uint_32,
                              png_get_cHRM) PNGARG ((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));
#      endif
#      ifdef PNG_FIXED_POINT_SUPPORTED
    extern        PNG_EXPORT (png_uint_32,
                              png_get_cHRM_fixed) PNGARG ((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));
#      endif
#    endif

#    if defined(PNG_cHRM_SUPPORTED)
#      ifdef PNG_FLOATING_POINT_SUPPORTED
    extern        PNG_EXPORT (void,
                              png_set_cHRM) PNGARG ((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));
#      endif
#      ifdef PNG_FIXED_POINT_SUPPORTED
    extern        PNG_EXPORT (void,
                              png_set_cHRM_fixed) PNGARG ((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));
#      endif
#    endif

#    if defined(PNG_gAMA_SUPPORTED)
#      ifdef PNG_FLOATING_POINT_SUPPORTED
    extern        PNG_EXPORT (png_uint_32,
                              png_get_gAMA) PNGARG ((png_structp png_ptr, png_infop info_ptr, double *file_gamma));
#      endif
    extern        PNG_EXPORT (png_uint_32,
                              png_get_gAMA_fixed) PNGARG ((png_structp png_ptr, png_infop info_ptr,
                                                           png_fixed_point * int_file_gamma));
#    endif

#    if defined(PNG_gAMA_SUPPORTED)
#      ifdef PNG_FLOATING_POINT_SUPPORTED
    extern        PNG_EXPORT (void, png_set_gAMA) PNGARG ((png_structp png_ptr, png_infop info_ptr, double file_gamma));
#      endif
    extern        PNG_EXPORT (void,
                              png_set_gAMA_fixed) PNGARG ((png_structp png_ptr, png_infop info_ptr,
                                                           png_fixed_point int_file_gamma));
#    endif

#    if defined(PNG_hIST_SUPPORTED)
    extern        PNG_EXPORT (png_uint_32,
                              png_get_hIST) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_16p * hist));
#    endif

#    if defined(PNG_hIST_SUPPORTED)
    extern        PNG_EXPORT (void, png_set_hIST) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_16p hist));
#    endif

    extern        PNG_EXPORT (png_uint_32,
                              png_get_IHDR) PNGARG ((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));

    extern        PNG_EXPORT (void,
                              png_set_IHDR) PNGARG ((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));

#    if defined(PNG_oFFs_SUPPORTED)
    extern        PNG_EXPORT (png_uint_32,
                              png_get_oFFs) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_int_32 * offset_x,
                                                     png_int_32 * offset_y, int *unit_type));
#    endif

#    if defined(PNG_oFFs_SUPPORTED)
    extern        PNG_EXPORT (void,
                              png_set_oFFs) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_int_32 offset_x,
                                                     png_int_32 offset_y, int unit_type));
#    endif

#    if defined(PNG_pCAL_SUPPORTED)
    extern        PNG_EXPORT (png_uint_32,
                              png_get_pCAL) PNGARG ((png_structp png_ptr, png_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

#    if defined(PNG_pCAL_SUPPORTED)
    extern        PNG_EXPORT (void,
                              png_set_pCAL) PNGARG ((png_structp png_ptr, png_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

#    if defined(PNG_pHYs_SUPPORTED)
    extern        PNG_EXPORT (png_uint_32,
                              png_get_pHYs) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 * res_x,
                                                     png_uint_32 * res_y, int *unit_type));
#    endif

#    if defined(PNG_pHYs_SUPPORTED)
    extern        PNG_EXPORT (void,
                              png_set_pHYs) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 res_x,
                                                     png_uint_32 res_y, int unit_type));
#    endif

    extern        PNG_EXPORT (png_uint_32,
                              png_get_PLTE) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_colorp * palette,
                                                     int *num_palette));

    extern        PNG_EXPORT (void,
                              png_set_PLTE) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_colorp palette,
                                                     int num_palette));

#    if defined(PNG_sBIT_SUPPORTED)
    extern        PNG_EXPORT (png_uint_32,
                              png_get_sBIT) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_color_8p * sig_bit));
#    endif

#    if defined(PNG_sBIT_SUPPORTED)
    extern        PNG_EXPORT (void,
                              png_set_sBIT) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_color_8p sig_bit));
#    endif

#    if defined(PNG_sRGB_SUPPORTED)
    extern        PNG_EXPORT (png_uint_32,
                              png_get_sRGB) PNGARG ((png_structp png_ptr, png_infop info_ptr, int *intent));
#    endif

#    if defined(PNG_sRGB_SUPPORTED)
    extern        PNG_EXPORT (void, png_set_sRGB) PNGARG ((png_structp png_ptr, png_infop info_ptr, int intent));
    extern        PNG_EXPORT (void,
                              png_set_sRGB_gAMA_and_cHRM) PNGARG ((png_structp png_ptr, png_infop info_ptr,
                                                                   int intent));
#    endif

#    if defined(PNG_iCCP_SUPPORTED)
    extern        PNG_EXPORT (png_uint_32,
                              png_get_iCCP) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_charpp name,
                                                     int *compression_type, png_charpp profile, png_uint_32 * proflen));
    /*
     * Note to maintainer: profile should be png_bytepp 
     */
#    endif

#    if defined(PNG_iCCP_SUPPORTED)
    extern        PNG_EXPORT (void,
                              png_set_iCCP) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_charp name,
                                                     int compression_type, png_charp profile, png_uint_32 proflen));
    /*
     * Note to maintainer: profile should be png_bytep 
     */
#    endif

#    if defined(PNG_sPLT_SUPPORTED)
    extern        PNG_EXPORT (png_uint_32,
                              png_get_sPLT) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_sPLT_tpp entries));
#    endif

#    if defined(PNG_sPLT_SUPPORTED)
    extern        PNG_EXPORT (void,
                              png_set_sPLT) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_sPLT_tp entries,
                                                     int nentries));
#    endif

#    if defined(PNG_TEXT_SUPPORTED)
    /*
     * png_get_text also returns the number of text chunks in *num_text 
     */
    extern        PNG_EXPORT (png_uint_32,
                              png_get_text) PNGARG ((png_structp png_ptr, png_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.
     */

#    if defined(PNG_TEXT_SUPPORTED)
    extern        PNG_EXPORT (void,
                              png_set_text) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_textp text_ptr,
                                                     int num_text));
#    endif

#    if defined(PNG_tIME_SUPPORTED)
    extern        PNG_EXPORT (png_uint_32,
                              png_get_tIME) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_timep * mod_time));
#    endif

#    if defined(PNG_tIME_SUPPORTED)
    extern        PNG_EXPORT (void,
                              png_set_tIME) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_timep mod_time));
#    endif

#    if defined(PNG_tRNS_SUPPORTED)
    extern        PNG_EXPORT (png_uint_32,
                              png_get_tRNS) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_bytep * trans,
                                                     int *num_trans, png_color_16p * trans_values));
#    endif

#    if defined(PNG_tRNS_SUPPORTED)
    extern        PNG_EXPORT (void,
                              png_set_tRNS) PNGARG ((png_structp png_ptr, png_infop info_ptr, png_bytep trans,
                                                     int num_trans, png_color_16p trans_values));
#    endif

#    if defined(PNG_tRNS_SUPPORTED)
#    endif

#    if defined(PNG_sCAL_SUPPORTED)
#      ifdef PNG_FLOATING_POINT_SUPPORTED
    extern        PNG_EXPORT (png_uint_32,
                              png_get_sCAL) PNGARG ((png_structp png_ptr, png_infop info_ptr, int *unit, double *width,
                                                     double *height));
#      else
#        ifdef PNG_FIXED_POINT_SUPPORTED
    extern        PNG_EXPORT (png_uint_32,
                              png_get_sCAL_s) PNGARG ((png_structp png_ptr, png_infop info_ptr, int *unit,
                                                       png_charpp swidth, png_charpp sheight));
#        endif
#      endif
#    endif                             /* PNG_sCAL_SUPPORTED */

#    if defined(PNG_sCAL_SUPPORTED)
#      ifdef PNG_FLOATING_POINT_SUPPORTED
    extern        PNG_EXPORT (void,
                              png_set_sCAL) PNGARG ((png_structp png_ptr, png_infop info_ptr, int unit, double width,
                                                     double height));
#      endif
#      ifdef PNG_FIXED_POINT_SUPPORTED
    extern        PNG_EXPORT (void,
                              png_set_sCAL_s) PNGARG ((png_structp png_ptr, png_infop info_ptr, int unit,
                                                       png_charp swidth, png_charp sheight));
#      endif
#    endif                             /* PNG_sCAL_SUPPORTED || PNG_WRITE_sCAL_SUPPORTED */

#    if defined(PNG_UNKNOWN_CHUNKS_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.
     * keep = 0: follow default behavour
     * = 1: do not keep
     * = 2: keep only if safe-to-copy
     * = 3: keep even if unsafe-to-copy
     */
    extern        PNG_EXPORT (void,
                              png_set_keep_unknown_chunks) PNGARG ((png_structp png_ptr, int keep, png_bytep chunk_list,
                                                                    int num_chunks));
    extern        PNG_EXPORT (void,
                              png_set_unknown_chunks) PNGARG ((png_structp png_ptr, png_infop info_ptr,
                                                               png_unknown_chunkp unknowns, int num_unknowns));
    extern        PNG_EXPORT (void, png_set_unknown_chunk_location)
                  PNGARG ((png_structp png_ptr, png_infop info_ptr, int chunk, int location));
    extern        PNG_EXPORT (png_uint_32,
                              png_get_unknown_chunks) PNGARG ((png_structp png_ptr, png_infop info_ptr,
                                                               png_unknown_chunkpp entries));
#    endif
#    ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
                  PNG_EXPORT (int, png_handle_as_unknown) PNGARG ((png_structp png_ptr, png_bytep chunk_name));
#    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); 
     */
    extern        PNG_EXPORT (void, png_set_invalid) PNGARG ((png_structp png_ptr, png_infop info_ptr, int mask));

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

    /*
     * Define PNG_DEBUG at compile time for debugging information.  Higher
     * * numbers for PNG_DEBUG mean more debugging information.  This has
     * * only been added since version 0.95 so it is not implemented throughout
     * * libpng yet, but more support will be added as needed.
     */
#    ifdef PNG_DEBUG
#      if (PNG_DEBUG > 0)
#        if !defined(PNG_DEBUG_FILE) && defined(_MSC_VER)
#          include <crtdbg.h>
#          if (PNG_DEBUG > 1)
#            define png_debug(l,m)  _RPT0(_CRT_WARN,m)
#            define png_debug1(l,m,p1)  _RPT1(_CRT_WARN,m,p1)
#            define png_debug2(l,m,p1,p2) _RPT2(_CRT_WARN,m,p1,p2)
#          endif
#        else                          /* PNG_DEBUG_FILE || !_MSC_VER */
#          ifndef PNG_DEBUG_FILE
#            define PNG_DEBUG_FILE stderr
#          endif                       /* PNG_DEBUG_FILE */
#          if (PNG_DEBUG > 1)
#            define png_debug(l,m) \
{ \
     int num_tabs=l; \
     fprintf(PNG_DEBUG_FILE,"%s"m,(num_tabs==1 ? "\t" : \
       (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":"")))); \
}
#            define png_debug1(l,m,p1) \
{ \
     int num_tabs=l; \
     fprintf(PNG_DEBUG_FILE,"%s"m,(num_tabs==1 ? "\t" : \
       (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))),p1); \
}
#            define png_debug2(l,m,p1,p2) \
{ \
     int num_tabs=l; \
     fprintf(PNG_DEBUG_FILE,"%s"m,(num_tabs==1 ? "\t" : \
       (num_tabs==2 ? "\t\t":(num_tabs>2 ? "\t\t\t":""))),p1,p2); \
}
#          endif                       /* (PNG_DEBUG > 1) */
#        endif                         /* _MSC_VER */
#      endif                           /* (PNG_DEBUG > 0) */
#    endif                             /* PNG_DEBUG */
#    ifndef png_debug
#      define png_debug(l, m)
#    endif
#    ifndef png_debug1
#      define png_debug1(l, m, p1)
#    endif
#    ifndef png_debug2
#      define png_debug2(l, m, p1, p2)
#    endif

    extern        PNG_EXPORT (png_bytep, png_sig_bytes) PNGARG ((void));

    extern        PNG_EXPORT (png_charp, png_get_copyright) PNGARG ((png_structp png_ptr));
    extern        PNG_EXPORT (png_charp, png_get_header_ver) PNGARG ((png_structp png_ptr));
    extern        PNG_EXPORT (png_charp, png_get_header_version) PNGARG ((png_structp png_ptr));
    extern        PNG_EXPORT (png_charp, png_get_libpng_ver) PNGARG ((png_structp png_ptr));

#    ifdef PNG_MNG_FEATURES_SUPPORTED
    extern        PNG_EXPORT (png_uint_32,
                              png_permit_mng_features) PNGARG ((png_structp png_ptr,
                                                                png_uint_32 mng_features_permitted));
#    endif

    /*
     * Added to version 1.2.0 
     */
#    if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
#      define PNG_ASM_FLAG_MMX_SUPPORT_COMPILED  0x01
                                                /* not user-settable */
#      define PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU    0x02
                                                /* not user-settable */
#      define PNG_ASM_FLAG_MMX_READ_COMBINE_ROW  0x04
#      define PNG_ASM_FLAG_MMX_READ_INTERLACE    0x08
#      define PNG_ASM_FLAG_MMX_READ_FILTER_SUB   0x10
#      define PNG_ASM_FLAG_MMX_READ_FILTER_UP    0x20
#      define PNG_ASM_FLAG_MMX_READ_FILTER_AVG   0x40
#      define PNG_ASM_FLAG_MMX_READ_FILTER_PAETH 0x80
#      define PNG_ASM_FLAGS_INITIALIZED          0x80000000
                                                        /* not user-settable */

#      define PNG_MMX_READ_FLAGS ( PNG_ASM_FLAG_MMX_READ_COMBINE_ROW  \
                           | PNG_ASM_FLAG_MMX_READ_INTERLACE    \
                           | PNG_ASM_FLAG_MMX_READ_FILTER_SUB   \
                           | PNG_ASM_FLAG_MMX_READ_FILTER_UP    \
                           | PNG_ASM_FLAG_MMX_READ_FILTER_AVG   \
                           | PNG_ASM_FLAG_MMX_READ_FILTER_PAETH )
#      define PNG_MMX_WRITE_FLAGS ( 0 )

#      define PNG_MMX_FLAGS ( PNG_ASM_FLAG_MMX_SUPPORT_COMPILED \
                      | PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU   \
                      | PNG_MMX_READ_FLAGS                \
                      | PNG_MMX_WRITE_FLAGS )

#      define PNG_SELECT_READ   1
#      define PNG_SELECT_WRITE  2

#      if !defined(PNG_1_0_X)
    /*
     * pngget.c 
     */
    extern        PNG_EXPORT (png_uint_32, png_get_mmx_flagmask)
                  PNGARG ((int flag_select, int *compilerID));

    /*
     * pngget.c 
     */
    extern        PNG_EXPORT (png_uint_32, png_get_asm_flagmask)
                  PNGARG ((int flag_select));

    /*
     * pngget.c 
     */
    extern        PNG_EXPORT (png_uint_32, png_get_asm_flags)
                  PNGARG ((png_structp png_ptr));

    /*
     * pngget.c 
     */
    extern        PNG_EXPORT (png_byte, png_get_mmx_bitdepth_threshold)
                  PNGARG ((png_structp png_ptr));

    /*
     * pngget.c 
     */
    extern        PNG_EXPORT (png_uint_32, png_get_mmx_rowbytes_threshold)
                  PNGARG ((png_structp png_ptr));

    /*
     * pngset.c 
     */
    extern        PNG_EXPORT (void, png_set_asm_flags)
                  PNGARG ((png_structp png_ptr, png_uint_32 asm_flags));

    /*
     * pngset.c 
     */
    extern        PNG_EXPORT (void, png_set_mmx_thresholds)
                  PNGARG ((png_structp png_ptr, png_byte mmx_bitdepth_threshold, png_uint_32 mmx_rowbytes_threshold));

#      endif                           /* PNG_1_0_X */
#    endif                             /* PNG_ASSEMBLER_CODE_SUPPORTED */

#    if !defined(PNG_1_0_X)
    /*
     * png.c, pnggccrd.c, or pngvcrd.c 
     */
    extern        PNG_EXPORT (int, png_mmx_support) PNGARG ((void));

    /*
     * 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
    extern        PNG_EXPORT (void, png_set_strip_error_numbers) PNGARG ((png_structp png_ptr, png_uint_32 strip_mode));
#      endif
#    endif                             /* PNG_1_0_X */

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

#    define PNG_HEADER_VERSION_STRING \
   " libpng version 1.2.5 - October 3, 2002 (header)\n"

#    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)) + (png_uint_16)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)*(png_uint_32)(65535L -           \
                        (png_uint_32)(alpha)) + (png_uint_32)32768L);        \
       (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)) +       \
       (png_uint_16)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)(65535L - (png_uint_32)(alpha)) +      \
       (png_uint_32)32767) / (png_uint_32)65535L)

#    endif                             /* PNG_READ_COMPOSITE_NODIV_SUPPORTED */

    /*
     * These next functions are used internally in the code.  They generally
     * * shouldn't be used unless you are writing code to add or replace some
     * * functionality in libpng.  More information about most functions can
     * * be found in the files where the functions are located.
     */

#    if defined(PNG_INTERNAL)

    /*
     * Various modes of operation.  Note that after an init, mode is set to
     * * zero automatically when the structure is created.
     */
#      define PNG_HAVE_IHDR               0x01
#      define PNG_HAVE_PLTE               0x02
#      define PNG_HAVE_IDAT               0x04
#      define PNG_AFTER_IDAT              0x08
#      define PNG_HAVE_IEND               0x10
#      define PNG_HAVE_gAMA               0x20
#      define PNG_HAVE_cHRM               0x40
#      define PNG_HAVE_sRGB               0x80
#      define PNG_HAVE_CHUNK_HEADER      0x100
#      define PNG_WROTE_tIME             0x200
#      define PNG_WROTE_INFO_BEFORE_PLTE 0x400
#      define PNG_BACKGROUND_IS_GRAY     0x800
#      define PNG_HAVE_PNG_SIGNATURE    0x1000

    /*
     * flags for the transformations the PNG library does on the image data 
     */
#      define PNG_BGR                0x0001
#      define PNG_INTERLACE          0x0002
#      define PNG_PACK               0x0004
#      define PNG_SHIFT              0x0008
#      define PNG_SWAP_BYTES         0x0010
#      define PNG_INVERT_MONO        0x0020
#      define PNG_DITHER             0x0040
#      define PNG_BACKGROUND         0x0080
#      define PNG_BACKGROUND_EXPAND  0x0100
    /*
     * 0x0200 unused 
     */
#      define PNG_16_TO_8            0x0400
#      define PNG_RGBA               0x0800
#      define PNG_EXPAND             0x1000
#      define PNG_GAMMA              0x2000
#      define PNG_GRAY_TO_RGB        0x4000
#      define PNG_FILLER             0x8000L
#      define PNG_PACKSWAP          0x10000L
#      define PNG_SWAP_ALPHA        0x20000L
#      define PNG_STRIP_ALPHA       0x40000L
#      define PNG_INVERT_ALPHA      0x80000L
#      define PNG_USER_TRANSFORM   0x100000L
#      define PNG_RGB_TO_GRAY_ERR  0x200000L
#      define PNG_RGB_TO_GRAY_WARN 0x400000L
#      define PNG_RGB_TO_GRAY      0x600000L
                                       /* two bits, RGB_TO_GRAY_ERR|WARN */

    /*
     * flags for png_create_struct 
     */
#      define PNG_STRUCT_PNG   0x0001
#      define PNG_STRUCT_INFO  0x0002

    /*
     * Scaling factor for filter heuristic weighting calculations 
     */
#      define PNG_WEIGHT_SHIFT 8
#      define PNG_WEIGHT_FACTOR (1<<(PNG_WEIGHT_SHIFT))
#      define PNG_COST_SHIFT 3
#      define PNG_COST_FACTOR (1<<(PNG_COST_SHIFT))

    /*
     * flags for the png_ptr->flags rather than declaring a byte for each one 
     */
#      define PNG_FLAG_ZLIB_CUSTOM_STRATEGY     0x0001
#      define PNG_FLAG_ZLIB_CUSTOM_LEVEL        0x0002
#      define PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL    0x0004
#      define PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS  0x0008
#      define PNG_FLAG_ZLIB_CUSTOM_METHOD       0x0010
#      define PNG_FLAG_ZLIB_FINISHED            0x0020
#      define PNG_FLAG_ROW_INIT                 0x0040
#      define PNG_FLAG_FILLER_AFTER             0x0080
#      define PNG_FLAG_CRC_ANCILLARY_USE        0x0100
#      define PNG_FLAG_CRC_ANCILLARY_NOWARN     0x0200
#      define PNG_FLAG_CRC_CRITICAL_USE         0x0400
#      define PNG_FLAG_CRC_CRITICAL_IGNORE      0x0800
#      define PNG_FLAG_FREE_PLTE                0x1000
#      define PNG_FLAG_FREE_TRNS                0x2000
#      define PNG_FLAG_FREE_HIST                0x4000
#      define PNG_FLAG_KEEP_UNKNOWN_CHUNKS      0x8000L
#      define PNG_FLAG_KEEP_UNSAFE_CHUNKS       0x10000L
#      define PNG_FLAG_LIBRARY_MISMATCH         0x20000L
#      define PNG_FLAG_STRIP_ERROR_NUMBERS      0x40000L
#      define PNG_FLAG_STRIP_ERROR_TEXT         0x80000L
#      define PNG_FLAG_MALLOC_NULL_MEM_OK       0x100000L

    /*
     * For use in png_set_keep_unknown, png_handle_as_unknown 
     */
#      define HANDLE_CHUNK_AS_DEFAULT   0
#      define HANDLE_CHUNK_NEVER        1
#      define HANDLE_CHUNK_IF_SAFE      2
#      define HANDLE_CHUNK_ALWAYS       3

#      define PNG_FLAG_CRC_ANCILLARY_MASK (PNG_FLAG_CRC_ANCILLARY_USE | \
                                     PNG_FLAG_CRC_ANCILLARY_NOWARN)

#      define PNG_FLAG_CRC_CRITICAL_MASK  (PNG_FLAG_CRC_CRITICAL_USE | \
                                     PNG_FLAG_CRC_CRITICAL_IGNORE)

#      define PNG_FLAG_CRC_MASK           (PNG_FLAG_CRC_ANCILLARY_MASK | \
                                     PNG_FLAG_CRC_CRITICAL_MASK)

    /*
     * save typing and make code easier to understand 
     */
#      define PNG_COLOR_DIST(c1, c2) (abs((int)((c1).red) - (int)((c2).red)) + \
   abs((int)((c1).green) - (int)((c2).green)) + \
   abs((int)((c1).blue) - (int)((c2).blue)))

    /*
     * variables declared in png.c - only it needs to define PNG_NO_EXTERN 
     */
#      if !defined(PNG_NO_EXTERN) || defined(PNG_ALWAYS_EXTERN)
    /*
     * place to hold the signature string for a PNG file. 
     */
#        ifdef PNG_USE_GLOBAL_ARRAYS
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_sig[8];
#        else
#          define png_sig png_sig_bytes(NULL)
#        endif
#      endif                           /* PNG_NO_EXTERN */

    /*
     * Constant strings for known chunk types.  If you need to add a chunk,
     * * define the name here, and add an invocation of the macro in png.c and
     * * wherever it's needed.
     */
#      define PNG_IHDR const png_byte png_IHDR[5] = { 73,  72,  68,  82, '\0'}
#      define PNG_IDAT const png_byte png_IDAT[5] = { 73,  68,  65,  84, '\0'}
#      define PNG_IEND const png_byte png_IEND[5] = { 73,  69,  78,  68, '\0'}
#      define PNG_PLTE const png_byte png_PLTE[5] = { 80,  76,  84,  69, '\0'}
#      define PNG_bKGD const png_byte png_bKGD[5] = { 98,  75,  71,  68, '\0'}
#      define PNG_cHRM const png_byte png_cHRM[5] = { 99,  72,  82,  77, '\0'}
#      define PNG_gAMA const png_byte png_gAMA[5] = {103,  65,  77,  65, '\0'}
#      define PNG_hIST const png_byte png_hIST[5] = {104,  73,  83,  84, '\0'}
#      define PNG_iCCP const png_byte png_iCCP[5] = {105,  67,  67,  80, '\0'}
#      define PNG_iTXt const png_byte png_iTXt[5] = {105,  84,  88, 116, '\0'}
#      define PNG_oFFs const png_byte png_oFFs[5] = {111,  70,  70, 115, '\0'}
#      define PNG_pCAL const png_byte png_pCAL[5] = {112,  67,  65,  76, '\0'}
#      define PNG_sCAL const png_byte png_sCAL[5] = {115,  67,  65,  76, '\0'}
#      define PNG_pHYs const png_byte png_pHYs[5] = {112,  72,  89, 115, '\0'}
#      define PNG_sBIT const png_byte png_sBIT[5] = {115,  66,  73,  84, '\0'}
#      define PNG_sPLT const png_byte png_sPLT[5] = {115,  80,  76,  84, '\0'}
#      define PNG_sRGB const png_byte png_sRGB[5] = {115,  82,  71,  66, '\0'}
#      define PNG_tEXt const png_byte png_tEXt[5] = {116,  69,  88, 116, '\0'}
#      define PNG_tIME const png_byte png_tIME[5] = {116,  73,  77,  69, '\0'}
#      define PNG_tRNS const png_byte png_tRNS[5] = {116,  82,  78,  83, '\0'}
#      define PNG_zTXt const png_byte png_zTXt[5] = {122,  84,  88, 116, '\0'}

#      ifdef PNG_USE_GLOBAL_ARRAYS
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_IHDR[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_IDAT[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_IEND[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_PLTE[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_bKGD[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_cHRM[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_gAMA[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_hIST[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_iCCP[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_iTXt[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_oFFs[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_pCAL[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_sCAL[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_pHYs[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_sBIT[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_sPLT[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_sRGB[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_tEXt[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_tIME[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_tRNS[5];
                  PNG_EXPORT_VAR (const png_byte FARDATA) png_zTXt[5];
#      endif                           /* PNG_USE_GLOBAL_ARRAYS */

    /*
     * Inline macros to do direct reads of bytes from the input buffer.  These
     * * require that you are using an architecture that uses PNG byte ordering
     * * (MSB first) and supports unaligned data storage.  I think that PowerPC
     * * in big-endian mode and 680x0 are the only ones that will support this.
     * * The x86 line of processors definitely do not.  The png_get_int_32()
     * * routine also assumes we are using two's complement format for negative
     * * values, which is almost certainly true.
     */
#      if defined(PNG_READ_BIG_ENDIAN_SUPPORTED)
#        if defined(PNG_pCAL_SUPPORTED) || defined(PNG_oFFs_SUPPORTED)
#          define png_get_int_32(buf) ( *((png_int_32p) (buf)))
#        endif
#        define png_get_uint_32(buf) ( *((png_uint_32p) (buf)))
#        define png_get_uint_16(buf) ( *((png_uint_16p) (buf)))
#      else
#        if defined(PNG_pCAL_SUPPORTED) || defined(PNG_oFFs_SUPPORTED)
    PNG_EXTERN png_int_32 png_get_int_32 PNGARG ((png_bytep buf));
#        endif
    PNG_EXTERN png_uint_32 png_get_uint_32 PNGARG ((png_bytep buf));
    PNG_EXTERN png_uint_16 png_get_uint_16 PNGARG ((png_bytep buf));
#      endif                           /* !PNG_READ_BIG_ENDIAN_SUPPORTED */

    /*
     * Initialize png_ptr struct for reading, and allocate any other memory.
     * * (old interface - DEPRECATED - use png_create_read_struct instead).
     */
    extern        PNG_EXPORT (void, png_read_init) PNGARG ((png_structp png_ptr));
#      undef png_read_init
#      define png_read_init(png_ptr) png_read_init_3(&png_ptr, \
    PNG_LIBPNG_VER_STRING,  sizeof(png_struct));
    extern        PNG_EXPORT (void,
                              png_read_init_3) PNGARG ((png_structpp ptr_ptr, png_const_charp user_png_ver,
                                                        png_size_t png_struct_size));
    extern        PNG_EXPORT (void,
                              png_read_init_2) PNGARG ((png_structp png_ptr, png_const_charp user_png_ver,
                                                        png_size_t png_struct_size, png_size_t png_info_size));

    /*
     * Initialize png_ptr struct for writing, and allocate any other memory.
     * * (old interface - DEPRECATED - use png_create_write_struct instead).
     */
    extern        PNG_EXPORT (void, png_write_init) PNGARG ((png_structp png_ptr));
#      undef png_write_init
#      define png_write_init(png_ptr) png_write_init_3(&png_ptr, \
    PNG_LIBPNG_VER_STRING, sizeof(png_struct));
    extern        PNG_EXPORT (void,
                              png_write_init_3) PNGARG ((png_structpp ptr_ptr, png_const_charp user_png_ver,
                                                         png_size_t png_struct_size));
    extern        PNG_EXPORT (void,
                              png_write_init_2) PNGARG ((png_structp png_ptr, png_const_charp user_png_ver,
                                                         png_size_t png_struct_size, png_size_t png_info_size));

    /*
     * Allocate memory for an internal libpng struct 
     */
    PNG_EXTERN png_voidp png_create_struct PNGARG ((int type));

    /*
     * Free memory from internal libpng struct 
     */
    PNG_EXTERN void png_destroy_struct PNGARG ((png_voidp struct_ptr));

    PNG_EXTERN png_voidp png_create_struct_2 PNGARG ((int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr));
    PNG_EXTERN void png_destroy_struct_2 PNGARG ((png_voidp struct_ptr, png_free_ptr free_fn, png_voidp mem_ptr));

    /*
     * Free any memory that info_ptr points to and reset struct. 
     */
    PNG_EXTERN void png_info_destroy PNGARG ((png_structp png_ptr, png_infop info_ptr));

#      ifndef PNG_1_0_X
    /*
     * Function to allocate memory for zlib. 
     */
    PNG_EXTERN voidpf png_zalloc PNGARG ((voidpf png_ptr, uInt items, uInt size));

    /*
     * Function to free memory for zlib 
     */
    PNG_EXTERN void png_zfree PNGARG ((voidpf png_ptr, voidpf ptr));

    /*
     * Next four functions are used internally as callbacks.  PNGAPI is required
     * * but not PNG_EXPORT.  PNGAPI added at libpng version 1.2.3. 
     */

    PNG_EXTERN void PNGAPI png_default_read_data PNGARG ((png_structp png_ptr, png_bytep data, png_size_t length));

#        ifdef PNG_PROGRESSIVE_READ_SUPPORTED
    PNG_EXTERN void PNGAPI png_push_fill_buffer PNGARG ((png_structp png_ptr, png_bytep buffer, png_size_t length));
#        endif

    PNG_EXTERN void PNGAPI png_default_write_data PNGARG ((png_structp png_ptr, png_bytep data, png_size_t length));

#        if defined(PNG_WRITE_FLUSH_SUPPORTED)
#          if !defined(PNG_NO_STDIO)
    PNG_EXTERN void PNGAPI png_default_flush PNGARG ((png_structp png_ptr));
#          endif
#        endif
#      else                            /* PNG_1_0_X */
#        ifdef PNG_PROGRESSIVE_READ_SUPPORTED
    PNG_EXTERN void png_push_fill_buffer PNGARG ((png_structp png_ptr, png_bytep buffer, png_size_t length));
#        endif
#      endif                           /* PNG_1_0_X */

    /*
     * Reset the CRC variable 
     */
    PNG_EXTERN void png_reset_crc PNGARG ((png_structp png_ptr));

    /*
     * Write the "data" buffer to whatever output you are using. 
     */
    PNG_EXTERN void png_write_data PNGARG ((png_structp png_ptr, png_bytep data, png_size_t length));

    /*
     * Read data from whatever input you are using into the "data" buffer 
     */
    PNG_EXTERN void png_read_data PNGARG ((png_structp png_ptr, png_bytep data, png_size_t length));

    /*
     * Read bytes into buf, and update png_ptr->crc 
     */
    PNG_EXTERN void png_crc_read PNGARG ((png_structp png_ptr, png_bytep buf, png_size_t length));

    /*
     * Decompress data in a chunk that uses compression 
     */
#      if defined(PNG_zTXt_SUPPORTED) || defined(PNG_iTXt_SUPPORTED) || \
    defined(PNG_iCCP_SUPPORTED) || defined(PNG_sPLT_SUPPORTED)
    PNG_EXTERN png_charp png_decompress_chunk
        PNGARG ((png_structp png_ptr, int comp_type, png_charp chunkdata, png_size_t chunklength,
                 png_size_t prefix_length, png_size_t * data_length));
#      endif

    /*
     * Read "skip" bytes, read the file crc, and (optionally) verify png_ptr->crc 
     */
    PNG_EXTERN int png_crc_finish PNGARG ((png_structp png_ptr, png_uint_32 skip));

    /*
     * Read the CRC from the file and compare it to the libpng calculated CRC 
     */
    PNG_EXTERN int png_crc_error PNGARG ((png_structp png_ptr));

    /*
     * Calculate the CRC over a section of data.  Note that we are only
     * * passing a maximum of 64K on systems that have this as a memory limit,
     * * since this is the maximum buffer size we can specify.
     */
    PNG_EXTERN void png_calculate_crc PNGARG ((png_structp png_ptr, png_bytep ptr, png_size_t length));

#      if defined(PNG_WRITE_FLUSH_SUPPORTED)
    PNG_EXTERN void png_flush PNGARG ((png_structp png_ptr));
#      endif

    /*
     * Place a 32-bit number into a buffer in PNG byte order (big-endian).
     * * The only currently known PNG chunks that use signed numbers are
     * * the ancillary extension chunks, oFFs and pCAL.
     */
    PNG_EXTERN void png_save_uint_32 PNGARG ((png_bytep buf, png_uint_32 i));

#      if defined(PNG_WRITE_pCAL_SUPPORTED) || defined(PNG_WRITE_oFFs_SUPPORTED)
    PNG_EXTERN void png_save_int_32 PNGARG ((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.
     */
    PNG_EXTERN void png_save_uint_16 PNGARG ((png_bytep buf, unsigned int i));

    /*
     * simple function to write the signature 
     */
    PNG_EXTERN void png_write_sig PNGARG ((png_structp png_ptr));

    /*
     * write various chunks 
     */

    /*
     * Write the IHDR chunk, and update the png_struct with the necessary
     * * information.
     */
    PNG_EXTERN void png_write_IHDR
        PNGARG ((png_structp png_ptr, png_uint_32 width, png_uint_32 height, int bit_depth, int color_type,
                 int compression_method, int filter_method, int interlace_method));

    PNG_EXTERN void png_write_PLTE PNGARG ((png_structp png_ptr, png_colorp palette, png_uint_32 num_pal));

    PNG_EXTERN void png_write_IDAT PNGARG ((png_structp png_ptr, png_bytep data, png_size_t length));

    PNG_EXTERN void png_write_IEND PNGARG ((png_structp png_ptr));

#      if defined(PNG_WRITE_gAMA_SUPPORTED)
#        ifdef PNG_FLOATING_POINT_SUPPORTED
    PNG_EXTERN void png_write_gAMA PNGARG ((png_structp png_ptr, double file_gamma));
#        endif
#        ifdef PNG_FIXED_POINT_SUPPORTED
    PNG_EXTERN void png_write_gAMA_fixed PNGARG ((png_structp png_ptr, png_fixed_point file_gamma));
#        endif
#      endif

#      if defined(PNG_WRITE_sBIT_SUPPORTED)
    PNG_EXTERN void png_write_sBIT PNGARG ((png_structp png_ptr, png_color_8p sbit, int color_type));
#      endif

#      if defined(PNG_WRITE_cHRM_SUPPORTED)
#        ifdef PNG_FLOATING_POINT_SUPPORTED
    PNG_EXTERN void png_write_cHRM
        PNGARG ((png_structp png_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));
#        endif
#        ifdef PNG_FIXED_POINT_SUPPORTED
    PNG_EXTERN void png_write_cHRM_fixed
        PNGARG ((png_structp png_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
#      endif

#      if defined(PNG_WRITE_sRGB_SUPPORTED)
    PNG_EXTERN void png_write_sRGB PNGARG ((png_structp png_ptr, int intent));
#      endif

#      if defined(PNG_WRITE_iCCP_SUPPORTED)
    PNG_EXTERN void png_write_iCCP
        PNGARG ((png_structp png_ptr, png_charp name, int compression_type, png_charp profile, int proflen));
    /*
     * Note to maintainer: profile should be png_bytep 
     */
#      endif

#      if defined(PNG_WRITE_sPLT_SUPPORTED)
    PNG_EXTERN void png_write_sPLT PNGARG ((png_structp png_ptr, png_sPLT_tp palette));
#      endif

#      if defined(PNG_WRITE_tRNS_SUPPORTED)
    PNG_EXTERN void png_write_tRNS
        PNGARG ((png_structp png_ptr, png_bytep trans, png_color_16p values, int number, int color_type));
#      endif

#      if defined(PNG_WRITE_bKGD_SUPPORTED)
    PNG_EXTERN void png_write_bKGD PNGARG ((png_structp png_ptr, png_color_16p values, int color_type));
#      endif

#      if defined(PNG_WRITE_hIST_SUPPORTED)
    PNG_EXTERN void png_write_hIST PNGARG ((png_structp png_ptr, png_uint_16p hist, int num_hist));
#      endif

#      if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \
    defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
    PNG_EXTERN png_size_t png_check_keyword PNGARG ((png_structp png_ptr, png_charp key, png_charpp new_key));
#      endif

#      if defined(PNG_WRITE_tEXt_SUPPORTED)
    PNG_EXTERN void png_write_tEXt PNGARG ((png_structp png_ptr, png_charp key, png_charp text, png_size_t text_len));
#      endif

#      if defined(PNG_WRITE_zTXt_SUPPORTED)
    PNG_EXTERN void png_write_zTXt
        PNGARG ((png_structp png_ptr, png_charp key, png_charp text, png_size_t text_len, int compression));
#      endif

#      if defined(PNG_WRITE_iTXt_SUPPORTED)
    PNG_EXTERN void png_write_iTXt
        PNGARG ((png_structp png_ptr, int compression, png_charp key, png_charp lang, png_charp lang_key,
                 png_charp text));
#      endif

#      if defined(PNG_TEXT_SUPPORTED)  /* Added at version 1.0.14 and 1.2.4 */
    PNG_EXTERN int png_set_text_2 PNGARG ((png_structp png_ptr, png_infop info_ptr, png_textp text_ptr, int num_text));
#      endif

#      if defined(PNG_WRITE_oFFs_SUPPORTED)
    PNG_EXTERN void png_write_oFFs
        PNGARG ((png_structp png_ptr, png_int_32 x_offset, png_int_32 y_offset, int unit_type));
#      endif

#      if defined(PNG_WRITE_pCAL_SUPPORTED)
    PNG_EXTERN void png_write_pCAL
        PNGARG ((png_structp png_ptr, png_charp purpose, png_int_32 X0, png_int_32 X1, int type, int nparams,
                 png_charp units, png_charpp params));
#      endif

#      if defined(PNG_WRITE_pHYs_SUPPORTED)
    PNG_EXTERN void png_write_pHYs
        PNGARG ((png_structp png_ptr, png_uint_32 x_pixels_per_unit, png_uint_32 y_pixels_per_unit, int unit_type));
#      endif

#      if defined(PNG_WRITE_tIME_SUPPORTED)
    PNG_EXTERN void png_write_tIME PNGARG ((png_structp png_ptr, png_timep mod_time));
#      endif

#      if defined(PNG_WRITE_sCAL_SUPPORTED)
#        if defined(PNG_FLOATING_POINT_SUPPORTED) && !defined(PNG_NO_STDIO)
    PNG_EXTERN void png_write_sCAL PNGARG ((png_structp png_ptr, int unit, double width, double height));
#        else
#          ifdef PNG_FIXED_POINT_SUPPORTED
    PNG_EXTERN void png_write_sCAL_s PNGARG ((png_structp png_ptr, int unit, png_charp width, png_charp height));
#          endif
#        endif
#      endif

    /*
     * Called when finished processing a row of data 
     */
    PNG_EXTERN void png_write_finish_row PNGARG ((png_structp png_ptr));

    /*
     * Internal use only.   Called before first row of data 
     */
    PNG_EXTERN void png_write_start_row PNGARG ((png_structp png_ptr));

#      if defined(PNG_READ_GAMMA_SUPPORTED)
    PNG_EXTERN void png_build_gamma_table PNGARG ((png_structp png_ptr));
#      endif

    /*
     * combine a row of data, dealing with alpha, etc. if requested 
     */
    PNG_EXTERN void png_combine_row PNGARG ((png_structp png_ptr, png_bytep row, int mask));

#      if defined(PNG_READ_INTERLACING_SUPPORTED)
    /*
     * expand an interlaced row 
     */
    /*
     * OLD pre-1.0.9 interface:
     * PNG_EXTERN void png_do_read_interlace PNGARG((png_row_infop row_info,
     * png_bytep row, int pass, png_uint_32 transformations));
     */
    PNG_EXTERN void png_do_read_interlace PNGARG ((png_structp png_ptr));
#      endif

    /*
     * GRR TO DO (2.0 or whenever):  simplify other internal calling interfaces 
     */

#      if defined(PNG_WRITE_INTERLACING_SUPPORTED)
    /*
     * grab pixels out of a row for an interlaced pass 
     */
    PNG_EXTERN void png_do_write_interlace PNGARG ((png_row_infop row_info, png_bytep row, int pass));
#      endif

    /*
     * unfilter a row 
     */
    PNG_EXTERN void png_read_filter_row
        PNGARG ((png_structp png_ptr, png_row_infop row_info, png_bytep row, png_bytep prev_row, int filter));

    /*
     * Choose the best filter to use and filter the row data 
     */
    PNG_EXTERN void png_write_find_filter PNGARG ((png_structp png_ptr, png_row_infop row_info));

    /*
     * Write out the filtered row. 
     */
    PNG_EXTERN void png_write_filtered_row PNGARG ((png_structp png_ptr, png_bytep filtered_row));
    /*
     * finish a row while reading, dealing with interlacing passes, etc. 
     */
    PNG_EXTERN void png_read_finish_row PNGARG ((png_structp png_ptr));

    /*
     * initialize the row buffers, etc. 
     */
    PNG_EXTERN void png_read_start_row PNGARG ((png_structp png_ptr));
    /*
     * optional call to update the users info structure 
     */
    PNG_EXTERN void png_read_transform_info PNGARG ((png_structp png_ptr, png_infop info_ptr));

    /*
     * these are the functions that do the transformations 
     */
#      if defined(PNG_READ_FILLER_SUPPORTED)
    PNG_EXTERN void png_do_read_filler
        PNGARG ((png_row_infop row_info, png_bytep row, png_uint_32 filler, png_uint_32 flags));
#      endif

#      if defined(PNG_READ_SWAP_ALPHA_SUPPORTED)
    PNG_EXTERN void png_do_read_swap_alpha PNGARG ((png_row_infop row_info, png_bytep row));
#      endif

#      if defined(PNG_WRITE_SWAP_ALPHA_SUPPORTED)
    PNG_EXTERN void png_do_write_swap_alpha PNGARG ((png_row_infop row_info, png_bytep row));
#      endif

#      if defined(PNG_READ_INVERT_ALPHA_SUPPORTED)
    PNG_EXTERN void png_do_read_invert_alpha PNGARG ((png_row_infop row_info, png_bytep row));
#      endif

#      if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
    PNG_EXTERN void png_do_write_invert_alpha PNGARG ((png_row_infop row_info, png_bytep row));
#      endif

#      if defined(PNG_WRITE_FILLER_SUPPORTED) || \
    defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
    PNG_EXTERN void png_do_strip_filler PNGARG ((png_row_infop row_info, png_bytep row, png_uint_32 flags));
#      endif

#      if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
    PNG_EXTERN void png_do_swap PNGARG ((png_row_infop row_info, png_bytep row));
#      endif

#      if defined(PNG_READ_PACKSWAP_SUPPORTED) || defined(PNG_WRITE_PACKSWAP_SUPPORTED)
    PNG_EXTERN void png_do_packswap PNGARG ((png_row_infop row_info, png_bytep row));
#      endif

#      if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
    PNG_EXTERN int png_do_rgb_to_gray PNGARG ((png_structp png_ptr, png_row_infop row_info, png_bytep row));
#      endif

#      if defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
    PNG_EXTERN void png_do_gray_to_rgb PNGARG ((png_row_infop row_info, png_bytep row));
#      endif

#      if defined(PNG_READ_PACK_SUPPORTED)
    PNG_EXTERN void png_do_unpack PNGARG ((png_row_infop row_info, png_bytep row));
#      endif

#      if defined(PNG_READ_SHIFT_SUPPORTED)
    PNG_EXTERN void png_do_unshift PNGARG ((png_row_infop row_info, png_bytep row, png_color_8p sig_bits));
#      endif

#      if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
    PNG_EXTERN void png_do_invert PNGARG ((png_row_infop row_info, png_bytep row));
#      endif

#      if defined(PNG_READ_16_TO_8_SUPPORTED)
    PNG_EXTERN void png_do_chop PNGARG ((png_row_infop row_info, png_bytep row));
#      endif

#      if defined(PNG_READ_DITHER_SUPPORTED)
    PNG_EXTERN void png_do_dither
        PNGARG ((png_row_infop row_info, png_bytep row, png_bytep palette_lookup, png_bytep dither_lookup));

#        if defined(PNG_CORRECT_PALETTE_SUPPORTED)
    PNG_EXTERN void png_correct_palette PNGARG ((png_structp png_ptr, png_colorp palette, int num_palette));
#        endif
#      endif

#      if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
    PNG_EXTERN void png_do_bgr PNGARG ((png_row_infop row_info, png_bytep row));
#      endif

#      if defined(PNG_WRITE_PACK_SUPPORTED)
    PNG_EXTERN void png_do_pack PNGARG ((png_row_infop row_info, png_bytep row, png_uint_32 bit_depth));
#      endif

#      if defined(PNG_WRITE_SHIFT_SUPPORTED)
    PNG_EXTERN void png_do_shift PNGARG ((png_row_infop row_info, png_bytep row, png_color_8p bit_depth));
#      endif

#      if defined(PNG_READ_BACKGROUND_SUPPORTED)
#        if defined(PNG_READ_GAMMA_SUPPORTED)
    PNG_EXTERN void png_do_background
        PNGARG ((png_row_infop row_info, png_bytep row, png_color_16p trans_values, png_color_16p background,
                 png_color_16p background_1, png_bytep gamma_table, png_bytep gamma_from_1, png_bytep gamma_to_1,
                 png_uint_16pp gamma_16, png_uint_16pp gamma_16_from_1, png_uint_16pp gamma_16_to_1, int gamma_shift));
#        else
    PNG_EXTERN void png_do_background
        PNGARG ((png_row_infop row_info, png_bytep row, png_color_16p trans_values, png_color_16p background));
#        endif
#      endif

#      if defined(PNG_READ_GAMMA_SUPPORTED)
    PNG_EXTERN void png_do_gamma
        PNGARG ((png_row_infop row_info, png_bytep row, png_bytep gamma_table, png_uint_16pp gamma_16_table,
                 int gamma_shift));
#      endif

#      if defined(PNG_READ_EXPAND_SUPPORTED)
    PNG_EXTERN void png_do_expand_palette
        PNGARG ((png_row_infop row_info, png_bytep row, png_colorp palette, png_bytep trans, int num_trans));
    PNG_EXTERN void png_do_expand PNGARG ((png_row_infop row_info, png_bytep row, png_color_16p trans_value));
#      endif

    /*
     * The following decodes the appropriate chunks, and does error correction,
     * * then calls the appropriate callback for the chunk if it is valid.
     */

    /*
     * decode the IHDR chunk 
     */
    PNG_EXTERN void png_handle_IHDR PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
    PNG_EXTERN void png_handle_PLTE PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
    PNG_EXTERN void png_handle_IEND PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));

#      if defined(PNG_READ_bKGD_SUPPORTED)
    PNG_EXTERN void png_handle_bKGD PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
#      endif

#      if defined(PNG_READ_cHRM_SUPPORTED)
    PNG_EXTERN void png_handle_cHRM PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
#      endif

#      if defined(PNG_READ_gAMA_SUPPORTED)
    PNG_EXTERN void png_handle_gAMA PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
#      endif

#      if defined(PNG_READ_hIST_SUPPORTED)
    PNG_EXTERN void png_handle_hIST PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
#      endif

#      if defined(PNG_READ_iCCP_SUPPORTED)
    extern void png_handle_iCCP PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
#      endif                           /* PNG_READ_iCCP_SUPPORTED */

#      if defined(PNG_READ_iTXt_SUPPORTED)
    PNG_EXTERN void png_handle_iTXt PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
#      endif

#      if defined(PNG_READ_oFFs_SUPPORTED)
    PNG_EXTERN void png_handle_oFFs PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
#      endif

#      if defined(PNG_READ_pCAL_SUPPORTED)
    PNG_EXTERN void png_handle_pCAL PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
#      endif

#      if defined(PNG_READ_pHYs_SUPPORTED)
    PNG_EXTERN void png_handle_pHYs PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
#      endif

#      if defined(PNG_READ_sBIT_SUPPORTED)
    PNG_EXTERN void png_handle_sBIT PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
#      endif

#      if defined(PNG_READ_sCAL_SUPPORTED)
    PNG_EXTERN void png_handle_sCAL PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
#      endif

#      if defined(PNG_READ_sPLT_SUPPORTED)
    extern void png_handle_sPLT PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
#      endif                           /* PNG_READ_sPLT_SUPPORTED */

#      if defined(PNG_READ_sRGB_SUPPORTED)
    PNG_EXTERN void png_handle_sRGB PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
#      endif

#      if defined(PNG_READ_tEXt_SUPPORTED)
    PNG_EXTERN void png_handle_tEXt PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
#      endif

#      if defined(PNG_READ_tIME_SUPPORTED)
    PNG_EXTERN void png_handle_tIME PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
#      endif

#      if defined(PNG_READ_tRNS_SUPPORTED)
    PNG_EXTERN void png_handle_tRNS PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
#      endif

#      if defined(PNG_READ_zTXt_SUPPORTED)
    PNG_EXTERN void png_handle_zTXt PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
#      endif

    PNG_EXTERN void png_handle_unknown PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));

    PNG_EXTERN void png_check_chunk_name PNGARG ((png_structp png_ptr, png_bytep chunk_name));

    /*
     * handle the transformations for reading and writing 
     */
    PNG_EXTERN void png_do_read_transformations PNGARG ((png_structp png_ptr));
    PNG_EXTERN void png_do_write_transformations PNGARG ((png_structp png_ptr));

    PNG_EXTERN void png_init_read_transformations PNGARG ((png_structp png_ptr));

#      ifdef PNG_PROGRESSIVE_READ_SUPPORTED
    PNG_EXTERN void png_push_read_chunk PNGARG ((png_structp png_ptr, png_infop info_ptr));
    PNG_EXTERN void png_push_read_sig PNGARG ((png_structp png_ptr, png_infop info_ptr));
    PNG_EXTERN void png_push_check_crc PNGARG ((png_structp png_ptr));
    PNG_EXTERN void png_push_crc_skip PNGARG ((png_structp png_ptr, png_uint_32 length));
    PNG_EXTERN void png_push_crc_finish PNGARG ((png_structp png_ptr));
    PNG_EXTERN void png_push_save_buffer PNGARG ((png_structp png_ptr));
    PNG_EXTERN void png_push_restore_buffer PNGARG ((png_structp png_ptr, png_bytep buffer, png_size_t buffer_length));
    PNG_EXTERN void png_push_read_IDAT PNGARG ((png_structp png_ptr));
    PNG_EXTERN void png_process_IDAT_data PNGARG ((png_structp png_ptr, png_bytep buffer, png_size_t buffer_length));
    PNG_EXTERN void png_push_process_row PNGARG ((png_structp png_ptr));
    PNG_EXTERN void png_push_handle_unknown PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
    PNG_EXTERN void png_push_have_info PNGARG ((png_structp png_ptr, png_infop info_ptr));
    PNG_EXTERN void png_push_have_end PNGARG ((png_structp png_ptr, png_infop info_ptr));
    PNG_EXTERN void png_push_have_row PNGARG ((png_structp png_ptr, png_bytep row));
    PNG_EXTERN void png_push_read_end PNGARG ((png_structp png_ptr, png_infop info_ptr));
    PNG_EXTERN void png_process_some_data PNGARG ((png_structp png_ptr, png_infop info_ptr));
    PNG_EXTERN void png_read_push_finish_row PNGARG ((png_structp png_ptr));
#        if defined(PNG_READ_tEXt_SUPPORTED)
    PNG_EXTERN void png_push_handle_tEXt PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
    PNG_EXTERN void png_push_read_tEXt PNGARG ((png_structp png_ptr, png_infop info_ptr));
#        endif
#        if defined(PNG_READ_zTXt_SUPPORTED)
    PNG_EXTERN void png_push_handle_zTXt PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
    PNG_EXTERN void png_push_read_zTXt PNGARG ((png_structp png_ptr, png_infop info_ptr));
#        endif
#        if defined(PNG_READ_iTXt_SUPPORTED)
    PNG_EXTERN void png_push_handle_iTXt PNGARG ((png_structp png_ptr, png_infop info_ptr, png_uint_32 length));
    PNG_EXTERN void png_push_read_iTXt PNGARG ((png_structp png_ptr, png_infop info_ptr));
#        endif

#      endif                           /* PNG_PROGRESSIVE_READ_SUPPORTED */

#      ifdef PNG_MNG_FEATURES_SUPPORTED
    PNG_EXTERN void png_do_read_intrapixel PNGARG ((png_row_infop row_info, png_bytep row));
    PNG_EXTERN void png_do_write_intrapixel PNGARG ((png_row_infop row_info, png_bytep row));
#      endif

#      if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
    /*
     * png.c 
     *//*
     * PRIVATE 
     */
    PNG_EXTERN void png_init_mmx_flags PNGARG ((png_structp png_ptr));
#      endif
    /*
     * Maintainer: Put new private prototypes here ^ and in libpngpf.3 
     */

#    endif                             /* PNG_INTERNAL */

#    ifdef __cplusplus
}
#    endif
#  endif                               /* PNG_VERSION_INFO_ONLY */
/*
 * do not put anything past this line 
 */
#endif                                 /* PNG_H */
