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src/Source/LibPNG/pngconf.h  view on Meta::CPAN

#endif

#ifdef PNG_CONVERT_tIME_SUPPORTED
   /* Required for struct tm: */
#  include <time.h>
#endif

#endif /* PNG_BUILDING_SYMBOL_TABLE */

/* Prior to 1.6.0 it was possible to turn off 'const' in declarations using
 * PNG_NO_CONST; this is no longer supported except for data declarations which
 * apparently still cause problems in 2011 on some compilers.
 */
#define PNG_CONST const /* backward compatibility only */

/* This controls optimization of the reading of 16 and 32 bit values
 * from PNG files.  It can be set on a per-app-file basis - it
 * just changes whether a macro is used when the function is called.
 * The library builder sets the default; if read functions are not
 * built into the library the macro implementation is forced on.
 */
#ifndef PNG_READ_INT_FUNCTIONS_SUPPORTED
#  define PNG_USE_READ_MACROS
#endif
#if !defined(PNG_NO_USE_READ_MACROS) && !defined(PNG_USE_READ_MACROS)
#  if PNG_DEFAULT_READ_MACROS
#    define PNG_USE_READ_MACROS
#  endif
#endif

/* COMPILER SPECIFIC OPTIONS.
 *
 * These options are provided so that a variety of difficult compilers
 * can be used.  Some are fixed at build time (e.g. PNG_API_RULE
 * below) but still have compiler specific implementations, others
 * may be changed on a per-file basis when compiling against libpng.
 */

/* The PNGARG macro was used in versions of libpng prior to 1.6.0 to protect
 * against legacy (pre ISOC90) compilers that did not understand function
 * prototypes.  It is not required for modern C compilers.
 */
#ifndef PNGARG
#  define PNGARG(arglist) arglist
#endif

/* Function calling conventions.
 * =============================
 * Normally it is not necessary to specify to the compiler how to call
 * a function - it just does it - however on x86 systems derived from
 * Microsoft and Borland C compilers ('IBM PC', 'DOS', 'Windows' systems
 * and some others) there are multiple ways to call a function and the
 * default can be changed on the compiler command line.  For this reason
 * libpng specifies the calling convention of every exported function and
 * every function called via a user supplied function pointer.  This is
 * done in this file by defining the following macros:
 *
 * PNGAPI    Calling convention for exported functions.
 * PNGCBAPI  Calling convention for user provided (callback) functions.
 * PNGCAPI   Calling convention used by the ANSI-C library (required
 *           for longjmp callbacks and sometimes used internally to
 *           specify the calling convention for zlib).
 *
 * These macros should never be overridden.  If it is necessary to
 * change calling convention in a private build this can be done
 * by setting PNG_API_RULE (which defaults to 0) to one of the values
 * below to select the correct 'API' variants.
 *
 * PNG_API_RULE=0 Use PNGCAPI - the 'C' calling convention - throughout.
 *                This is correct in every known environment.
 * PNG_API_RULE=1 Use the operating system convention for PNGAPI and
 *                the 'C' calling convention (from PNGCAPI) for
 *                callbacks (PNGCBAPI).  This is no longer required
 *                in any known environment - if it has to be used
 *                please post an explanation of the problem to the
 *                libpng mailing list.
 *
 * These cases only differ if the operating system does not use the C
 * calling convention, at present this just means the above cases
 * (x86 DOS/Windows sytems) and, even then, this does not apply to
 * Cygwin running on those systems.
 *
 * Note that the value must be defined in pnglibconf.h so that what
 * the application uses to call the library matches the conventions
 * set when building the library.
 */

/* Symbol export
 * =============
 * When building a shared library it is almost always necessary to tell
 * the compiler which symbols to export.  The png.h macro 'PNG_EXPORT'
 * is used to mark the symbols.  On some systems these symbols can be
 * extracted at link time and need no special processing by the compiler,
 * on other systems the symbols are flagged by the compiler and just
 * the declaration requires a special tag applied (unfortunately) in a
 * compiler dependent way.  Some systems can do either.
 *
 * A small number of older systems also require a symbol from a DLL to
 * be flagged to the program that calls it.  This is a problem because
 * we do not know in the header file included by application code that
 * the symbol will come from a shared library, as opposed to a statically
 * linked one.  For this reason the application must tell us by setting
 * the magic flag PNG_USE_DLL to turn on the special processing before
 * it includes png.h.
 *
 * Four additional macros are used to make this happen:
 *
 * PNG_IMPEXP The magic (if any) to cause a symbol to be exported from
 *            the build or imported if PNG_USE_DLL is set - compiler
 *            and system specific.
 *
 * PNG_EXPORT_TYPE(type) A macro that pre or appends PNG_IMPEXP to
 *                       'type', compiler specific.
 *
 * PNG_DLL_EXPORT Set to the magic to use during a libpng build to
 *                make a symbol exported from the DLL.  Not used in the
 *                public header files; see pngpriv.h for how it is used
 *                in the libpng build.
 *
 * PNG_DLL_IMPORT Set to the magic to force the libpng symbols to come
 *                from a DLL - used to define PNG_IMPEXP when
 *                PNG_USE_DLL is set.
 */

/* System specific discovery.
 * ==========================
 * This code is used at build time to find PNG_IMPEXP, the API settings
 * and PNG_EXPORT_TYPE(), it may also set a macro to indicate the DLL
 * import processing is possible.  On Windows systems it also sets
 * compiler-specific macros to the values required to change the calling
 * conventions of the various functions.
 */
#if defined(_Windows) || defined(_WINDOWS) || defined(WIN32) ||\