pngconf.h

一个国人自己实现图像库的程序（有参考价值）

/* pngconf.h - machine configurable file for libpng
 *
 * libpng 1.2.1 - December 12, 2001
 * For conditions of distribution and use, see copyright notice in png.h
 * Copyright (c) 1998-2001 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.)
 */

/* Any machine specific code is near the front of this file, so if you
 * are configuring libpng for a machine, you may want to read the section
 * starting here down to where it starts to typedef png_color, png_text,
 * and png_info.
 */

#ifndef PNGCONF_H
#define PNGCONF_H

/* This is the size of the compression buffer, and thus the size of
 * an IDAT chunk.  Make this whatever size you feel is best for your
 * machine.  One of these will be allocated per png_struct.  When this
 * is full, it writes the data to the disk, and does some other
 * calculations.  Making this an extremely small size will slow
 * the library down, but you may want to experiment to determine
 * where it becomes significant, if you are concerned with memory
 * usage.  Note that zlib allocates at least 32Kb also.  For readers,
 * this describes the size of the buffer available to read the data in.
 * Unless this gets smaller than the size of a row (compressed),
 * it should not make much difference how big this is.
 */

#ifndef PNG_ZBUF_SIZE
#  define PNG_ZBUF_SIZE 8192
#endif

/* Enable if you want a write-only libpng */

#ifndef PNG_NO_READ_SUPPORTED
#  define PNG_READ_SUPPORTED
#endif

/* Enable if you want a read-only libpng */

#ifndef PNG_NO_WRITE_SUPPORTED
#  define PNG_WRITE_SUPPORTED
#endif

/* Enabled by default in 1.2.0.  You can disable this if you don't need to
   support PNGs that are embedded in MNG datastreams */
#ifndef PNG_NO_MNG_FEATURES
#  ifndef PNG_MNG_FEATURES_SUPPORTED
#    define PNG_MNG_FEATURES_SUPPORTED
#  endif
#endif

#ifndef PNG_NO_FLOATING_POINT_SUPPORTED
#  ifndef PNG_FLOATING_POINT_SUPPORTED
#    define PNG_FLOATING_POINT_SUPPORTED
#  endif
#endif

/* If you are running on a machine where you cannot allocate more
 * than 64K of memory at once, uncomment this.  While libpng will not
 * normally need that much memory in a chunk (unless you load up a very
 * large file), zlib needs to know how big of a chunk it can use, and
 * libpng thus makes sure to check any memory allocation to verify it
 * will fit into memory.
#define PNG_MAX_MALLOC_64K
 */
#if defined(MAXSEG_64K) && !defined(PNG_MAX_MALLOC_64K)
#  define PNG_MAX_MALLOC_64K
#endif

/* Special munging to support doing things the 'cygwin' way:
 * 'Normal' png-on-win32 defines/defaults:
 *   PNG_BUILD_DLL -- building dll
 *   PNG_USE_DLL   -- building an application, linking to dll
 *   (no define)   -- building static library, or building an
 *                    application and linking to the static lib
 * 'Cygwin' defines/defaults:
 *   PNG_BUILD_DLL -- building the dll
 *   (no define)   -- building an application, linking to the dll
 *   PNG_STATIC    -- building the static lib, or building an application
 *                    that links to the static lib.
 *   ALL_STATIC    -- building various static libs, or building an application
 *                    that links to the static libs.
 * Thus,
 * a cygwin user should define either PNG_BUILD_DLL or PNG_STATIC, and
 * this bit of #ifdefs will define the 'correct' config variables based on
 * that. If a cygwin user *wants* to define 'PNG_USE_DLL' that's okay, but
 * unnecessary.
 *
 * Also, the precedence order is:
 *   ALL_STATIC (since we can't #undef something outside our namespace)
 *   PNG_BUILD_DLL
 *   PNG_STATIC
 *   (nothing) == PNG_USE_DLL 
 */
#if defined(__CYGWIN__)
#  if defined(ALL_STATIC)
#    if defined(PNG_BUILD_DLL)
#      undef PNG_BUILD_DLL
#    endif
#    if defined(PNG_USE_DLL)
#      undef PNG_USE_DLL
#    endif
#    if defined(PNG_DLL)
#      undef PNG_DLL
#    endif
#    if !defined(PNG_STATIC)
#      define PNG_STATIC
#    endif
#  else
#    if defined (PNG_BUILD_DLL)
#      if defined(PNG_STATIC)
#        undef PNG_STATIC
#      endif
#      if defined(PNG_USE_DLL)
#        undef PNG_USE_DLL
#      endif
#      if !defined(PNG_DLL)
#        define PNG_DLL
#      endif
#    else
#      if defined(PNG_STATIC)
#        if defined(PNG_USE_DLL)
#          undef PNG_USE_DLL
#        endif
#        if defined(PNG_DLL)
#          undef PNG_DLL
#        endif
#      else
#        if !defined(PNG_USE_DLL)
#          define PNG_USE_DLL
#        endif
#        if !defined(PNG_DLL)
#          define PNG_DLL
#        endif
#      endif  
#    endif  
#  endif
#endif

/* This protects us against compilers that run on a windowing system
 * and thus don't have or would rather us not use the stdio types:
 * stdin, stdout, and stderr.  The only one currently used is stderr
 * in png_error() and png_warning().  #defining PNG_NO_CONSOLE_IO will
 * prevent these from being compiled and used. #defining PNG_NO_STDIO
 * will also prevent these, plus will prevent the entire set of stdio
 * macros and functions (FILE *, printf, etc.) from being compiled and used,
 * unless (PNG_DEBUG > 0) has been #defined.
 *
 * #define PNG_NO_CONSOLE_IO
 * #define PNG_NO_STDIO
 */

#if defined(_WIN32_WCE)
#  include <windows.h>
   /* Console I/O functions are not supported on WindowsCE */
#  define PNG_NO_CONSOLE_IO
#  ifdef PNG_DEBUG
#    undef PNG_DEBUG
#  endif
#endif

#ifdef PNG_BUILD_DLL
#  ifndef PNG_CONSOLE_IO_SUPPORTED
#    ifndef PNG_NO_CONSOLE_IO
#      define PNG_NO_CONSOLE_IO
#    endif
#  endif
#endif

#  ifdef PNG_NO_STDIO
#    ifndef PNG_NO_CONSOLE_IO
#      define PNG_NO_CONSOLE_IO
#    endif
#    ifdef PNG_DEBUG
#      if (PNG_DEBUG > 0)
#        include <stdio.h>
#      endif
#    endif
#  else
#    if !defined(_WIN32_WCE)
/* "stdio.h" functions are not supported on WindowsCE */
#      include <stdio.h>
#    endif
#  endif

/* This macro protects us against machines that don't have function
 * prototypes (ie K&R style headers).  If your compiler does not handle
 * function prototypes, define this macro and use the included ansi2knr.
 * I've always been able to use _NO_PROTO as the indicator, but you may
 * need to drag the empty declaration out in front of here, or change the
 * ifdef to suit your own needs.
 */
#ifndef PNGARG

#ifdef OF /* zlib prototype munger */
#  define PNGARG(arglist) OF(arglist)
#else

#ifdef _NO_PROTO
#  define PNGARG(arglist) ()
#  ifndef PNG_TYPECAST_NULL
#     define PNG_TYPECAST_NULL
#  endif
#else
#  define PNGARG(arglist) arglist
#endif /* _NO_PROTO */

#endif /* OF */

#endif /* PNGARG */

/* Try to determine if we are compiling on a Mac.  Note that testing for
 * just __MWERKS__ is not good enough, because the Codewarrior is now used
 * on non-Mac platforms.
 */
#ifndef MACOS
#  if (defined(__MWERKS__) && defined(macintosh)) || defined(applec) || \
      defined(THINK_C) || defined(__SC__) || defined(TARGET_OS_MAC)
#    define MACOS
#  endif
#endif

/* enough people need this for various reasons to include it here */
#if !defined(MACOS) && !defined(RISCOS) && !defined(_WIN32_WCE)
#  include <sys/types.h>
#endif

#if !defined(PNG_SETJMP_NOT_SUPPORTED) && !defined(PNG_NO_SETJMP_SUPPORTED)
#  define PNG_SETJMP_SUPPORTED
#endif

#ifdef PNG_SETJMP_SUPPORTED
/* This is an attempt to force a single setjmp behaviour on Linux.  If
 * the X config stuff didn't define _BSD_SOURCE we wouldn't need this.
 */

#  ifdef __linux__
#    ifdef _BSD_SOURCE
#      define PNG_SAVE_BSD_SOURCE
#      undef _BSD_SOURCE
#    endif
#    ifdef _SETJMP_H
      __png.h__ already includes setjmp.h;
      __dont__ include it again.;
#    endif
#  endif /* __linux__ */

   /* include setjmp.h for error handling */
#  include <setjmp.h>

#  ifdef __linux__
#    ifdef PNG_SAVE_BSD_SOURCE
#      define _BSD_SOURCE
#      undef PNG_SAVE_BSD_SOURCE
#    endif
#  endif /* __linux__ */
#endif /* PNG_SETJMP_SUPPORTED */

#ifdef BSD
#  include <strings.h>
#else
#  include <string.h>
#endif

/* Other defines for things like memory and the like can go here.  */
#ifdef PNG_INTERNAL

#include <stdlib.h>

/* The functions exported by PNG_EXTERN are PNG_INTERNAL functions, which
 * aren't usually used outside the library (as far as I know), so it is
 * debatable if they should be exported at all.  In the future, when it is
 * possible to have run-time registry of chunk-handling functions, some of
 * these will be made available again.
#define PNG_EXTERN extern
 */
#define PNG_EXTERN

/* Other defines specific to compilers can go here.  Try to keep
 * them inside an appropriate ifdef/endif pair for portability.
 */

#if defined(PNG_FLOATING_POINT_SUPPORTED)
#  if defined(MACOS)
     /* We need to check that <math.h> hasn't already been included earlier
      * as it seems it doesn't agree with <fp.h>, yet we should really use
      * <fp.h> if possible.
      */
#    if !defined(__MATH_H__) && !defined(__MATH_H) && !defined(__cmath__)
#      include <fp.h>
#    endif
#  else
#    include <math.h>
#  endif
#  if defined(_AMIGA) && defined(__SASC) && defined(_M68881)
     /* Amiga SAS/C: We must include builtin FPU functions when compiling using
      * MATH=68881
      */
#    include <m68881.h>
#  endif
#endif

/* Codewarrior on NT has linking problems without this. */
#if (defined(__MWERKS__) && defined(WIN32)) || defined(__STDC__)
#  define PNG_ALWAYS_EXTERN
#endif

/* For some reason, Borland C++ defines memcmp, etc. in mem.h, not
 * stdlib.h like it should (I think).  Or perhaps this is a C++
 * "feature"?
 */
#ifdef __TURBOC__
#  include <mem.h>
#  include "alloc.h"
#endif

#if defined(_MSC_VER) && (defined(WIN32) || defined(_Windows) || \
    defined(_WINDOWS) || defined(_WIN32) || defined(__WIN32__))
#  include <malloc.h>
#endif

/* This controls how fine the dithering gets.  As this allocates
 * a largish chunk of memory (32K), those who are not as concerned
 * with dithering quality can decrease some or all of these.
 */
#ifndef PNG_DITHER_RED_BITS
#  define PNG_DITHER_RED_BITS 5
#endif
#ifndef PNG_DITHER_GREEN_BITS
#  define PNG_DITHER_GREEN_BITS 5
#endif
#ifndef PNG_DITHER_BLUE_BITS
#  define PNG_DITHER_BLUE_BITS 5
#endif

/* This controls how fine the gamma correction becomes when you
 * are only interested in 8 bits anyway.  Increasing this value
 * results in more memory being used, and more pow() functions
 * being called to fill in the gamma tables.  Don't set this value
 * less then 8, and even that may not work (I haven't tested it).
 */

#ifndef PNG_MAX_GAMMA_8
#  define PNG_MAX_GAMMA_8 11
#endif

/* This controls how much a difference in gamma we can tolerate before
 * we actually start doing gamma conversion.
 */
#ifndef PNG_GAMMA_THRESHOLD
#  define PNG_GAMMA_THRESHOLD 0.05
#endif

#endif /* PNG_INTERNAL */

/* The following uses const char * instead of char * for error
 * and warning message functions, so some compilers won't complain.
 * If you do not want to use const, define PNG_NO_CONST here.
 */

#ifndef PNG_NO_CONST
#  define PNG_CONST const
#else
#  define PNG_CONST
#endif

/* The following defines give you the ability to remove code from the
 * library that you will not be using.  I wish I could figure out how to
 * automate this, but I can't do that without making it seriously hard
 * on the users.  So if you are not using an ability, change the #define
 * to and #undef, and that part of the library will not be compiled.  If
 * your linker can't find a function, you may want to make sure the
 * ability is defined here.  Some of these depend upon some others being
 * defined.  I haven't figured out all the interactions here, so you may
 * have to experiment awhile to get everything to compile.  If you are
 * creating or using a shared library, you probably shouldn't touch this,
 * as it will affect the size of the structures, and this will cause bad
 * things to happen if the library and/or application ever change.
 */

/* Any features you will not be using can be undef'ed here */

/* GR-P, 0.96a: Set "*TRANSFORMS_SUPPORTED as default but allow user
 * to turn it off with "*TRANSFORMS_NOT_SUPPORTED" or *PNG_NO_*_TRANSFORMS
 * on the compile line, then pick and choose which ones to define without
 * having to edit this file. It is safe to use the *TRANSFORMS_NOT_SUPPORTED
 * if you only want to have a png-compliant reader/writer but don't need
 * any of the extra transformations.  This saves about 80 kbytes in a
 * typical installation of the library. (PNG_NO_* form added in version
 * 1.0.1c, for consistency)
 */

/* The size of the png_text structure changed in libpng-1.0.6 when
 * iTXt is supported.  It is turned off by default, to support old apps
 * that malloc the png_text structure instead of calling png_set_text()
 * and letting libpng malloc it.  It will be turned on by default in
 * libpng-1.3.0.
 */

#ifndef PNG_iTXt_SUPPORTED
#  if !defined(PNG_READ_iTXt_SUPPORTED) && !defined(PNG_NO_READ_iTXt)
#    define PNG_NO_READ_iTXt
#  endif
#  if !defined(PNG_WRITE_iTXt_SUPPORTED) && !defined(PNG_NO_WRITE_iTXt)
#    define PNG_NO_WRITE_iTXt
#  endif
#endif

/* The following support, added after version 1.0.0, can be turned off here en
 * masse by defining PNG_LEGACY_SUPPORTED in case you need binary compatibility
 * with old applications that require the length of png_struct and png_info
 * to remain unchanged.
 */

#ifdef PNG_LEGACY_SUPPORTED
#  define PNG_NO_FREE_ME
#  define PNG_NO_READ_UNKNOWN_CHUNKS
#  define PNG_NO_WRITE_UNKNOWN_CHUNKS
#  define PNG_NO_READ_USER_CHUNKS
#  define PNG_NO_READ_iCCP
#  define PNG_NO_WRITE_iCCP
#  define PNG_NO_READ_iTXt
#  define PNG_NO_WRITE_iTXt
#  define PNG_NO_READ_sCAL
#  define PNG_NO_WRITE_sCAL
#  define PNG_NO_READ_sPLT
#  define PNG_NO_WRITE_sPLT
#  define PNG_NO_INFO_IMAGE
#  define PNG_NO_READ_RGB_TO_GRAY
#  define PNG_NO_READ_USER_TRANSFORM
#  define PNG_NO_WRITE_USER_TRANSFORM
#  define PNG_NO_USER_MEM
#  define PNG_NO_READ_EMPTY_PLTE
#  define PNG_NO_MNG_FEATURES
#  define PNG_NO_FIXED_POINT_SUPPORTED
#endif

/* Ignore attempt to turn off both floating and fixed point support */
#if !defined(PNG_FLOATING_POINT_SUPPORTED) || \
    !defined(PNG_NO_FIXED_POINT_SUPPORTED)