/* png.h - header file for PNG reference library

 *

 * libpng version 1.2.57, December 29, 2016

 *

 * Copyright (c) 1998-2016 Glenn Randers-Pehrson

 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)

 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)

 *

 * This code is released under the libpng license (See LICENSE, below)

 *

 * Authors and maintainers:

 *  libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat

 *  libpng versions 0.89, June 1996, through 0.96, May 1997: Andreas Dilger

 *  libpng versions 0.97, January 1998, through 1.2.57, December 29, 2016: Glenn

 *  See also "Contributing Authors", below.

 */

/*

 * COPYRIGHT NOTICE, DISCLAIMER, and LICENSE:

 *

 * If you modify libpng you may insert additional notices immediately following

 * this sentence.

 *

 * This code is released under the libpng license.

 *

 * libpng versions 1.0.7, July 1, 2000, through 1.2.57, December 29, 2016, are

 * Copyright (c) 2000-2002, 2004, 2006-2016 Glenn Randers-Pehrson, are

 * derived from libpng-1.0.6, and are distributed according to the same

 * disclaimer and license as libpng-1.0.6 with the following individuals

 * added to the list of Contributing Authors:

 *

 *    Simon-Pierre Cadieux

 *    Eric S. Raymond

 *    Cosmin Truta

 *    Gilles Vollant

 *

 * and with the following additions to the disclaimer:

 *

 *    There is no warranty against interference with your enjoyment of the

 *    library or against infringement.  There is no warranty that our

 *    efforts or the library will fulfill any of your particular purposes

 *    or needs.  This library is provided with all faults, and the entire

 *    risk of satisfactory quality, performance, accuracy, and effort is with

 *    the user.

 *

 * libpng versions 0.97, January 1998, through 1.0.6, March 20, 2000, are

 * Copyright (c) 1998-2000 Glenn Randers-Pehrson, are derived from

 * libpng-0.96, and are distributed according to the same disclaimer and

 * license as libpng-0.96, with the following individuals added to the list

 * of Contributing Authors:

 *

 *    Tom Lane

 *    Glenn Randers-Pehrson

 *    Willem van Schaik

 *

 * libpng versions 0.89, June 1996, through 0.96, May 1997, are

 * Copyright (c) 1996-1997 Andreas Dilger, are derived from libpng-0.88,

 * and are distributed according to the same disclaimer and license as

 * libpng-0.88, with the following individuals added to the list of

 * Contributing Authors:

 *

 *    John Bowler

 *    Kevin Bracey

 *    Sam Bushell

 *    Magnus Holmgren

 *    Greg Roelofs

 *    Tom Tanner

 *

 * libpng versions 0.5, May 1995, through 0.88, January 1996, are

 * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.

 *

 * For the purposes of this copyright and license, "Contributing Authors"

 * is defined as the following set of individuals:

 *

 *    Andreas Dilger

 *    Dave Martindale

 *    Guy Eric Schalnat

 *    Paul Schmidt

 *    Tim Wegner

 *

 * The PNG Reference Library is supplied "AS IS".  The Contributing Authors

 * and Group 42, Inc. disclaim all warranties, expressed or implied,

 * including, without limitation, the warranties of merchantability and of

 * fitness for any purpose.  The Contributing Authors and Group 42, Inc.

 * assume no liability for direct, indirect, incidental, special, exemplary,

 * or consequential damages, which may result from the use of the PNG

 * Reference Library, even if advised of the possibility of such damage.

 *

 * Permission is hereby granted to use, copy, modify, and distribute this

 * source code, or portions hereof, for any purpose, without fee, subject

 * to the following restrictions:

 *

 *   1. The origin of this source code must not be misrepresented.

 *

 *   2. Altered versions must be plainly marked as such and must not

 *      be misrepresented as being the original source.

 *

 *   3. This Copyright notice may not be removed or altered from any

 *      source or altered source distribution.

 *

 * The Contributing Authors and Group 42, Inc. specifically permit, without

 * fee, and encourage the use of this source code as a component to

 * supporting the PNG file format in commercial products.  If you use this

 * source code in a product, acknowledgment is not required but would be

 * appreciated.

 *

 * END OF COPYRIGHT NOTICE, DISCLAIMER, and LICENSE.

 */

/*

 * A "png_get_copyright" function is available, for convenient use in "about"

 * boxes and the like:

 *

 *    printf("%s", png_get_copyright(NULL));

 *

 * Also, the PNG logo (in PNG format, of course) is supplied in the

 * files "pngbar.png" and "pngbar.jpg (88x31) and "pngnow.png" (98x31).

 */

/*

 * Libpng is OSI Certified Open Source Software.  OSI Certified Open Source is

 * a certification mark of the Open Source Initiative. OSI has not addressed

 * the additional disclaimers inserted at version 1.0.7.

 */

/*

 * The contributing authors would like to thank all those who helped

 * with testing, bug fixes, and patience.  This wouldn't have been

 * possible without all of you.

 *

 * Thanks to Frank J. T. Wojcik for helping with the documentation.

 */

/* Note about libpng version numbers:

 *

 *    Due to various miscommunications, unforeseen code incompatibilities

 *    and occasional factors outside the authors' control, version numbering

 *    on the library has not always been consistent and straightforward.

 *    The following table summarizes matters since version 0.89c, which was

 *    the first widely used release:

 *

 *    source                 png.h  png.h  shared-lib

 *    version                string   int  version

 *    -------                ------ -----  ----------

 *    0.89c "1.0 beta 3"     0.89      89  1.0.89

 *    0.90  "1.0 beta 4"     0.90      90  0.90  [should have been 2.0.90]

 *    0.95  "1.0 beta 5"     0.95      95  0.95  [should have been 2.0.95]

 *    0.96  "1.0 beta 6"     0.96      96  0.96  [should have been 2.0.96]

 *    0.97b "1.00.97 beta 7" 1.00.97   97  1.0.1 [should have been 2.0.97]

 *    0.97c                  0.97      97  2.0.97

 *    0.98                   0.98      98  2.0.98

 *    0.99                   0.99      98  2.0.99

 *    0.99a-m                0.99      99  2.0.99

 *    1.00                   1.00     100  2.1.0 [100 should be 10000]

 *    1.0.0      (from here on, the   100  2.1.0 [100 should be 10000]

 *    1.0.1       png.h string is   10001  2.1.0

 *    1.0.1a-e    identical to the  10002  from here on, the shared library

 *    1.0.2       source version)   10002  is 2.V where V is the source code

 *    1.0.2a-b                      10003  version, except as noted.

 *    1.0.3                         10003

 *    1.0.3a-d                      10004

 *    1.0.4                         10004

 *    1.0.4a-f                      10005

 *    1.0.5 (+ 2 patches)           10005

 *    1.0.5a-d                      10006

 *    1.0.5e-r                      10100 (not source compatible)

 *    1.0.5s-v                      10006 (not binary compatible)

 *    1.0.6 (+ 3 patches)           10006 (still binary incompatible)

 *    1.0.6d-f                      10007 (still binary incompatible)

 *    1.0.6g                        10007

 *    1.0.6h                        10007  10.6h (testing xy.z so-numbering)

 *    1.0.6i                        10007  10.6i

 *    1.0.6j                        10007  2.1.0.6j (incompatible with 1.0.0)

 *    1.0.7beta11-14        DLLNUM  10007  2.1.0.7beta11-14 (binary compatible)

 *    1.0.7beta15-18           1    10007  2.1.0.7beta15-18 (binary compatible)

 *    1.0.7rc1-2               1    10007  2.1.0.7rc1-2 (binary compatible)

 *    1.0.7                    1    10007  (still compatible)

 *    ...

 *    1.0.19                  10    10019  10.so.0.19[.0]

 *    ...

 *    1.0.67                  10    10067  10.so.0.67[.0]

 *    1.2.57                  13    10257  12.so.0.57[.0]

 *

 *    Henceforth the source version will match the shared-library major

 *    and minor numbers; the shared-library major version number will be

 *    used for changes in backward compatibility, as it is intended.  The

 *    PNG_LIBPNG_VER macro, which is not used within libpng but is available

 *    for applications, is an unsigned integer of the form xyyzz corresponding

 *    to the source version x.y.z (leading zeros in y and z).  Beta versions

 *    were given the previous public release number plus a letter, until

 *    version 1.0.6j; from then on they were given the upcoming public

 *    release number plus "betaNN" or "rcNN".

 *

 *    Binary incompatibility exists only when applications make direct access

 *    to the info_ptr or png_ptr members through png.h, and the compiled

 *    application is loaded with a different version of the library.

 *

 *    DLLNUM will change each time there are forward or backward changes

 *    in binary compatibility (e.g., when a new feature is added).

 *

 * See libpng.txt or libpng.3 for more information.  The PNG specification

 * is available as a W3C Recommendation and as an ISO Specification,

 * 

 */

/*

 * Y2K compliance in libpng:

 * =========================

 *

 *    December 29, 2016

 *

 *    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 1.2.57 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 "1.2.57"

#define PNG_HEADER_VERSION_STRING \

   " libpng version 1.2.57 - December 29, 2016\n"

#define PNG_LIBPNG_VER_SONUM   0

#define PNG_LIBPNG_VER_DLLNUM  13

/* 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 57

/* This should match the numeric part of the final component of

 * PNG_LIBPNG_VER_STRING, omitting any leading zero:

 */

#define PNG_LIBPNG_VER_BUILD  0

/* Release Status */

#define PNG_LIBPNG_BUILD_ALPHA    1

#define PNG_LIBPNG_BUILD_BETA     2

#define PNG_LIBPNG_BUILD_RC       3

#define PNG_LIBPNG_BUILD_STABLE   4

#define PNG_LIBPNG_BUILD_RELEASE_STATUS_MASK 7

/* Release-Specific Flags */

#define PNG_LIBPNG_BUILD_PATCH    8 /* Can be OR'ed with

                                       PNG_LIBPNG_BUILD_STABLE only */

#define PNG_LIBPNG_BUILD_PRIVATE 16 /* Cannot be OR'ed with

                                       PNG_LIBPNG_BUILD_SPECIAL */

#define PNG_LIBPNG_BUILD_SPECIAL 32 /* Cannot be OR'ed with

                                       PNG_LIBPNG_BUILD_PRIVATE */

#define PNG_LIBPNG_BUILD_BASE_TYPE PNG_LIBPNG_BUILD_STABLE

/* Careful here.  At one time, Guy wanted to use 082, but that would be octal.

 * We must not include leading zeros.

 * Versions 0.7 through 1.0.0 were in the range 0 to 100 here (only

 * version 1.0.0 was mis-numbered 100 instead of 10000).  From

 * version 1.0.1 it's    xxyyzz, where x=major, y=minor, z=release

 */

#define PNG_LIBPNG_VER 10257 /* 1.2.57 */

#ifndef PNG_VERSION_INFO_ONLY

/* Include the compression library's header */

#include "zlib.h"

#endif

/* Include all user configurable info, including optional assembler routines */

#include "pngconf.h"

/*

 * Added at libpng-1.2.8 */

/* Ref MSDN: Private as priority over Special

 * VS_FF_PRIVATEBUILD File *was not* built using standard release

 * procedures. If this value is given, the StringFileInfo block must

 * contain a PrivateBuild string.

 *

 * VS_FF_SPECIALBUILD File *was* built by the original company using

 * standard release procedures but is a variation of the standard

 * file of the same version number. If this value is given, the

 * StringFileInfo block must contain a SpecialBuild string.

 */

#ifdef PNG_USER_PRIVATEBUILD

#  define PNG_LIBPNG_BUILD_TYPE \

          (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_PRIVATE)

#else

#  ifdef PNG_LIBPNG_SPECIALBUILD

#    define PNG_LIBPNG_BUILD_TYPE \

            (PNG_LIBPNG_BUILD_BASE_TYPE | PNG_LIBPNG_BUILD_SPECIAL)

#  else

#    define PNG_LIBPNG_BUILD_TYPE (PNG_LIBPNG_BUILD_BASE_TYPE)

#  endif

#endif

#ifndef PNG_VERSION_INFO_ONLY

/* Inhibit C++ name-mangling for libpng functions but not for system calls. */

#ifdef __cplusplus

extern "C" {

#endif /* __cplusplus */

/* 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 (PNG_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 (PNG_CONST int FARDATA) png_pass_start[7];

PNG_EXPORT_VAR (PNG_CONST int FARDATA) png_pass_inc[7];

PNG_EXPORT_VAR (PNG_CONST int FARDATA) png_pass_ystart[7];

PNG_EXPORT_VAR (PNG_CONST int FARDATA) png_pass_yinc[7];

PNG_EXPORT_VAR (PNG_CONST int FARDATA) png_pass_mask[7];

PNG_EXPORT_VAR (PNG_CONST int FARDATA) png_pass_dsp_mask[7];

/* This isn't currently used.  If you need it, see png.c for more details.

PNG_EXPORT_VAR (PNG_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) || \

 defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)

/* png_unknown_chunk is a structure to hold queued chunks for which there is

 * no specific support.  The idea is that we can use this to queue

 * up private chunks for output even though the library doesn't actually

 * know about their semantics.

 */

#define PNG_CHUNK_NAME_LENGTH 5

typedef struct png_unknown_chunk_t

{

    png_byte name[PNG_CHUNK_NAME_LENGTH];

    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 PNG_DEPSTRUCT;       /* width of image in pixels (from IHDR) */

   png_uint_32 height PNG_DEPSTRUCT;      /* height of image in pixels (from IHDR) */

   png_uint_32 valid PNG_DEPSTRUCT;       /* valid chunk data (see PNG_INFO_ below) */

   png_uint_32 rowbytes PNG_DEPSTRUCT;    /* bytes needed to hold an untransformed row */

   png_colorp palette PNG_DEPSTRUCT;      /* array of color values (valid & PNG_INFO_PLTE) */

   png_uint_16 num_palette PNG_DEPSTRUCT; /* number of color entries in "palette" (PLTE) */

   png_uint_16 num_trans PNG_DEPSTRUCT;   /* number of transparent palette color (tRNS) */

   png_byte bit_depth PNG_DEPSTRUCT;      /* 1, 2, 4, 8, or 16 bits/channel (from IHDR) */

   png_byte color_type PNG_DEPSTRUCT;     /* see PNG_COLOR_TYPE_ below (from IHDR) */

   /* The following three should have been named *_method not *_type */

   png_byte compression_type PNG_DEPSTRUCT; /* must be PNG_COMPRESSION_TYPE_BASE (IHDR) */

   png_byte filter_type PNG_DEPSTRUCT;    /* must be PNG_FILTER_TYPE_BASE (from IHDR) */

   png_byte interlace_type PNG_DEPSTRUCT; /* One of PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */

   /* The following is informational only on read, and not used on writes. */

   png_byte channels PNG_DEPSTRUCT;       /* number of data channels per pixel (1, 2, 3, 4) */

   png_byte pixel_depth PNG_DEPSTRUCT;    /* number of bits per pixel */

   png_byte spare_byte PNG_DEPSTRUCT;     /* to align the data, and for future use */

   png_byte signature[8] PNG_DEPSTRUCT;   /* 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 PNG_DEPSTRUCT; /* gamma value of image, if (valid & PNG_INFO_gAMA) */

#endif

#ifdef PNG_sRGB_SUPPORTED

    /* GR-P, 0.96a */

    /* Data valid if (valid & PNG_INFO_sRGB) non-zero. */

   png_byte srgb_intent PNG_DEPSTRUCT; /* sRGB rendering intent [0, 1, 2, or 3] */

#endif

#ifdef 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 PNG_DEPSTRUCT; /* number of comments read/to write */

   int max_text PNG_DEPSTRUCT; /* current size of text array */

   png_textp text PNG_DEPSTRUCT; /* array of comments read/to write */

#endif /* PNG_TEXT_SUPPORTED */

#ifdef 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 PNG_DEPSTRUCT;

#endif

#ifdef 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 PNG_DEPSTRUCT; /* 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 PNG_DEPSTRUCT; /* transparent values for paletted image */

   png_color_16 trans_values PNG_DEPSTRUCT; /* 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 PNG_DEPSTRUCT;

#endif

#ifdef 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 PNG_DEPSTRUCT; /* x offset on page */

   png_int_32 y_offset PNG_DEPSTRUCT; /* y offset on page */

   png_byte offset_unit_type PNG_DEPSTRUCT; /* offset units type */

#endif

#ifdef 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 PNG_DEPSTRUCT; /* horizontal pixel density */

   png_uint_32 y_pixels_per_unit PNG_DEPSTRUCT; /* vertical pixel density */

   png_byte phys_unit_type PNG_DEPSTRUCT; /* resolution type (see PNG_RESOLUTION_ below) */

#endif

#ifdef 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 PNG_DEPSTRUCT;

#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 PNG_DEPSTRUCT;

   float y_white PNG_DEPSTRUCT;

   float x_red PNG_DEPSTRUCT;

   float y_red PNG_DEPSTRUCT;

   float x_green PNG_DEPSTRUCT;

   float y_green PNG_DEPSTRUCT;

   float x_blue PNG_DEPSTRUCT;

   float y_blue PNG_DEPSTRUCT;

#endif

#endif

#ifdef 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 PNG_DEPSTRUCT;  /* pCAL chunk description string */

   png_int_32 pcal_X0 PNG_DEPSTRUCT;      /* minimum value */

   png_int_32 pcal_X1 PNG_DEPSTRUCT;      /* maximum value */

   png_charp pcal_units PNG_DEPSTRUCT;    /* Latin-1 string giving physical units */

   png_charpp pcal_params PNG_DEPSTRUCT;  /* ASCII strings containing parameter values */

   png_byte pcal_type PNG_DEPSTRUCT;      /* equation type (see PNG_EQUATION_ below) */

   png_byte pcal_nparams PNG_DEPSTRUCT;   /* 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 PNG_DEPSTRUCT;     /* flags items libpng is responsible for freeing */

#endif

#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) || \

 defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)

   /* Storage for unknown chunks that the library doesn't recognize. */

   png_unknown_chunkp unknown_chunks PNG_DEPSTRUCT;

   png_size_t unknown_chunks_num PNG_DEPSTRUCT;

#endif

#ifdef PNG_iCCP_SUPPORTED

   /* iCCP chunk data. */

   png_charp iccp_name PNG_DEPSTRUCT;     /* profile name */

   png_charp iccp_profile PNG_DEPSTRUCT;  /* International Color Consortium profile data */

                            /* Note to maintainer: should be png_bytep */

   png_uint_32 iccp_proflen PNG_DEPSTRUCT;  /* ICC profile data length */

   png_byte iccp_compression PNG_DEPSTRUCT; /* Always zero */

#endif

#ifdef PNG_sPLT_SUPPORTED

   /* Data on sPLT chunks (there may be more than one). */

   png_sPLT_tp splt_palettes PNG_DEPSTRUCT;

   png_uint_32 splt_palettes_num PNG_DEPSTRUCT;

#endif

#ifdef 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 PNG_DEPSTRUCT;         /* unit of physical scale */

#ifdef PNG_FLOATING_POINT_SUPPORTED

   double scal_pixel_width PNG_DEPSTRUCT;    /* width of one pixel */

   double scal_pixel_height PNG_DEPSTRUCT;   /* height of one pixel */

#endif

#ifdef PNG_FIXED_POINT_SUPPORTED

   png_charp scal_s_width PNG_DEPSTRUCT;     /* string containing height */

   png_charp scal_s_height PNG_DEPSTRUCT;    /* string containing width */

#endif

#endif

#ifdef 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 PNG_DEPSTRUCT;        /* the image bits */

#endif

#if defined(PNG_FIXED_POINT_SUPPORTED) && defined(PNG_gAMA_SUPPORTED)

   png_fixed_point int_gamma PNG_DEPSTRUCT; /* 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_DEPSTRUCT;

   png_fixed_point int_y_white PNG_DEPSTRUCT;

   png_fixed_point int_x_red PNG_DEPSTRUCT;

   png_fixed_point int_y_red PNG_DEPSTRUCT;

   png_fixed_point int_x_green PNG_DEPSTRUCT;

   png_fixed_point int_y_green PNG_DEPSTRUCT;

   png_fixed_point int_x_blue PNG_DEPSTRUCT;

   png_fixed_point int_y_blue PNG_DEPSTRUCT;

#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_UINT_31_MAX ((png_uint_32)0x7fffffffL)

#define PNG_UINT_32_MAX ((png_uint_32)(-1))

#define PNG_SIZE_MAX ((png_size_t)(-1))

#if defined(PNG_1_0_X) || defined (PNG_1_2_X)

/* PNG_MAX_UINT is deprecated; use PNG_UINT_31_MAX instead. */

#define PNG_MAX_UINT PNG_UINT_31_MAX

#endif

/* 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