png.c

一个国人自己实现图像库的程序（有参考价值）

        png_free(png_ptr, info_ptr->pcal_params);
        info_ptr->pcal_params = NULL;
    }
    info_ptr->valid &= ~PNG_INFO_pCAL;
}
#endif

#if defined(PNG_iCCP_SUPPORTED)
/* free any iCCP entry */
#ifdef PNG_FREE_ME_SUPPORTED
if ((mask & PNG_FREE_ICCP) & info_ptr->free_me)
#else
if (mask & PNG_FREE_ICCP)
#endif
{
    png_free(png_ptr, info_ptr->iccp_name);
    png_free(png_ptr, info_ptr->iccp_profile);
    info_ptr->iccp_name = NULL;
    info_ptr->iccp_profile = NULL;
    info_ptr->valid &= ~PNG_INFO_iCCP;
}
#endif

#if defined(PNG_sPLT_SUPPORTED)
/* free a given sPLT entry, or (if num == -1) all sPLT entries */
#ifdef PNG_FREE_ME_SUPPORTED
if ((mask & PNG_FREE_SPLT) & info_ptr->free_me)
#else
if (mask & PNG_FREE_SPLT)
#endif
{
   if (num != -1)
   {
      if(info_ptr->splt_palettes)
      {
          png_free(png_ptr, info_ptr->splt_palettes[num].name);
          png_free(png_ptr, info_ptr->splt_palettes[num].entries);
          info_ptr->splt_palettes[num].name = NULL;
          info_ptr->splt_palettes[num].entries = NULL;
      }
   }
   else
   {
       if(info_ptr->splt_palettes_num)
       {
         int i;
         for (i = 0; i < (int)info_ptr->splt_palettes_num; i++)
            png_free_data(png_ptr, info_ptr, PNG_FREE_SPLT, i);

         png_free(png_ptr, info_ptr->splt_palettes);
         info_ptr->splt_palettes = NULL;
         info_ptr->splt_palettes_num = 0;
       }
       info_ptr->valid &= ~PNG_INFO_sPLT;
   }
}
#endif

#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
#ifdef PNG_FREE_ME_SUPPORTED
if ((mask & PNG_FREE_UNKN) & info_ptr->free_me)
#else
if (mask & PNG_FREE_UNKN)
#endif
{
   if (num != -1)
   {
       if(info_ptr->unknown_chunks)
       {
          png_free(png_ptr, info_ptr->unknown_chunks[num].data);
          info_ptr->unknown_chunks[num].data = NULL;
       }
   }
   else
   {
       int i;

       if(info_ptr->unknown_chunks_num)
       {
         for (i = 0; i < (int)info_ptr->unknown_chunks_num; i++)
            png_free_data(png_ptr, info_ptr, PNG_FREE_UNKN, i);

         png_free(png_ptr, info_ptr->unknown_chunks);
         info_ptr->unknown_chunks = NULL;
         info_ptr->unknown_chunks_num = 0;
       }
   }
}
#endif

#if defined(PNG_hIST_SUPPORTED)
/* free any hIST entry */
#ifdef PNG_FREE_ME_SUPPORTED
if ((mask & PNG_FREE_HIST)  & info_ptr->free_me)
#else
if ((mask & PNG_FREE_HIST) && (png_ptr->flags & PNG_FLAG_FREE_HIST))
#endif
{
    png_free(png_ptr, info_ptr->hist);
    info_ptr->hist = NULL;
    info_ptr->valid &= ~PNG_INFO_hIST;
}
#endif

/* free any PLTE entry that was internally allocated */
#ifdef PNG_FREE_ME_SUPPORTED
if ((mask & PNG_FREE_PLTE) & info_ptr->free_me)
#else
if ((mask & PNG_FREE_PLTE) && (png_ptr->flags & PNG_FLAG_FREE_PLTE))
#endif
{
    png_zfree(png_ptr, info_ptr->palette);
    info_ptr->palette = NULL;
    info_ptr->valid &= ~PNG_INFO_PLTE;
    info_ptr->num_palette = 0;
}

#if defined(PNG_INFO_IMAGE_SUPPORTED)
/* free any image bits attached to the info structure */
#ifdef PNG_FREE_ME_SUPPORTED
if ((mask & PNG_FREE_ROWS) & info_ptr->free_me)
#else
if (mask & PNG_FREE_ROWS)
#endif
{
    if(info_ptr->row_pointers)
    {
       int row;
       for (row = 0; row < (int)info_ptr->height; row++)
       {
          png_free(png_ptr, info_ptr->row_pointers[row]);
          info_ptr->row_pointers[row]=NULL;
       }
       png_free(png_ptr, info_ptr->row_pointers);
       info_ptr->row_pointers=NULL;
    }
    info_ptr->valid &= ~PNG_INFO_IDAT;
}
#endif

#ifdef PNG_FREE_ME_SUPPORTED
   if(num == -1)
     info_ptr->free_me &= ~mask;
   else
     info_ptr->free_me &= ~(mask & ~PNG_FREE_MUL);
#endif
}

/* This is an internal routine to free any memory that the info struct is
 * pointing to before re-using it or freeing the struct itself.  Recall
 * that png_free() checks for NULL pointers for us.
 */
void /* PRIVATE */
png_info_destroy(png_structp png_ptr, png_infop info_ptr)
{
   png_debug(1, "in png_info_destroy\n");

   png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);

#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
   if (png_ptr->num_chunk_list)
   {
       png_free(png_ptr, png_ptr->chunk_list);
       png_ptr->chunk_list=NULL;
       png_ptr->num_chunk_list=0;
   }
#endif

   png_info_init_3(&info_ptr, sizeof(png_info));
}

/* This function returns a pointer to the io_ptr associated with the user
 * functions.  The application should free any memory associated with this
 * pointer before png_write_destroy() or png_read_destroy() are called.
 */
png_voidp PNGAPI
png_get_io_ptr(png_structp png_ptr)
{
   return (png_ptr->io_ptr);
}

#if !defined(PNG_NO_STDIO)
/* Initialize the default input/output functions for the PNG file.  If you
 * use your own read or write routines, you can call either png_set_read_fn()
 * or png_set_write_fn() instead of png_init_io().  If you have defined
 * PNG_NO_STDIO, you must use a function of your own because "FILE *" isn't
 * necessarily available.
 */
void PNGAPI
png_init_io(png_structp png_ptr, png_FILE_p fp)
{
   png_debug(1, "in png_init_io\n");
   png_ptr->io_ptr = (png_voidp)fp;
}
#endif

#if defined(PNG_TIME_RFC1123_SUPPORTED)
/* Convert the supplied time into an RFC 1123 string suitable for use in
 * a "Creation Time" or other text-based time string.
 */
png_charp PNGAPI
png_convert_to_rfc1123(png_structp png_ptr, png_timep ptime)
{
   static PNG_CONST char short_months[12][4] =
        {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
         "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};

   if (png_ptr->time_buffer == NULL)
   {
      png_ptr->time_buffer = (png_charp)png_malloc(png_ptr, (png_uint_32)(29*
         sizeof(char)));
   }

#if defined(_WIN32_WCE)
   {
      wchar_t time_buf[29];
      wsprintf(time_buf, TEXT("%d %S %d %02d:%02d:%02d +0000"),
          ptime->day % 32, short_months[(ptime->month - 1) % 12],
        ptime->year, ptime->hour % 24, ptime->minute % 60,
          ptime->second % 61);
      WideCharToMultiByte(CP_ACP, 0, time_buf, -1, png_ptr->time_buffer, 29,
          NULL, NULL);
   }
#else
#ifdef USE_FAR_KEYWORD
   {
      char near_time_buf[29];
      sprintf(near_time_buf, "%d %s %d %02d:%02d:%02d +0000",
          ptime->day % 32, short_months[(ptime->month - 1) % 12],
          ptime->year, ptime->hour % 24, ptime->minute % 60,
          ptime->second % 61);
      png_memcpy(png_ptr->time_buffer, near_time_buf,
          29*sizeof(char));
   }
#else
   sprintf(png_ptr->time_buffer, "%d %s %d %02d:%02d:%02d +0000",
       ptime->day % 32, short_months[(ptime->month - 1) % 12],
       ptime->year, ptime->hour % 24, ptime->minute % 60,
       ptime->second % 61);
#endif
#endif /* _WIN32_WCE */
   return ((png_charp)png_ptr->time_buffer);
}
#endif /* PNG_TIME_RFC1123_SUPPORTED */

#if 0
/* Signature string for a PNG file. */
png_bytep PNGAPI
png_sig_bytes(void)
{
   return ((png_bytep)"\211\120\116\107\015\012\032\012");
}
#endif

png_charp PNGAPI
png_get_copyright(png_structp png_ptr)
{
   if (png_ptr != NULL || png_ptr == NULL)  /* silence compiler warning */
   return ((png_charp) "\n libpng version 1.2.1 - December 12, 2001\n\
   Copyright (c) 1998-2001 Glenn Randers-Pehrson\n\
   Copyright (c) 1996, 1997 Andreas Dilger\n\
   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.\n");
   return ((png_charp) "");
}

/* The following return the library version as a short string in the
 * format 1.0.0 through 99.99.99zz.  To get the version of *.h files used
 * with your application, print out PNG_LIBPNG_VER_STRING, which is defined
 * in png.h.
 */

png_charp PNGAPI
png_get_libpng_ver(png_structp png_ptr)
{
   /* Version of *.c files used when building libpng */
   if(png_ptr != NULL) /* silence compiler warning about unused png_ptr */
      return((png_charp) "1.2.1");
   return((png_charp) "1.2.1");
}

png_charp PNGAPI
png_get_header_ver(png_structp png_ptr)
{
   /* Version of *.h files used when building libpng */
   if(png_ptr != NULL) /* silence compiler warning about unused png_ptr */
      return((png_charp) PNG_LIBPNG_VER_STRING);
   return((png_charp) PNG_LIBPNG_VER_STRING);
}

png_charp PNGAPI
png_get_header_version(png_structp png_ptr)
{
   /* Returns longer string containing both version and date */
   if(png_ptr != NULL) /* silence compiler warning about unused png_ptr */
      return((png_charp) PNG_HEADER_VERSION_STRING);
   return((png_charp) PNG_HEADER_VERSION_STRING);
}

#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
int /* PRIVATE */
png_handle_as_unknown(png_structp png_ptr, png_bytep chunk_name)
{
   /* check chunk_name and return "keep" value if it's on the list, else 0 */
   int i;
   png_bytep p;
   if((png_ptr == NULL && chunk_name == NULL) || png_ptr->num_chunk_list<=0)
      return 0;
   p=png_ptr->chunk_list+png_ptr->num_chunk_list*5-5;
   for (i = png_ptr->num_chunk_list; i; i--, p-=5)
      if (!png_memcmp(chunk_name, p, 4))
        return ((int)*(p+4));
   return 0;
}
#endif

/* This function, added to libpng-1.0.6g, is untested. */
int PNGAPI
png_reset_zstream(png_structp png_ptr)
{
   return (inflateReset(&png_ptr->zstream));
}

/* This function was added to libpng-1.0.7 */
png_uint_32 PNGAPI
png_access_version_number(void)
{
   /* Version of *.c files used when building libpng */
   return((png_uint_32) 10201L);
}


#if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
    /* GRR:  could add this:   && defined(PNG_MMX_CODE_SUPPORTED) */
/* this INTERNAL function was added to libpng 1.2.0 */
void /* PRIVATE */
png_init_mmx_flags (png_structp png_ptr)
{
    png_ptr->mmx_rowbytes_threshold = 0;
    png_ptr->mmx_bitdepth_threshold = 0;

#  if (defined(PNG_USE_PNGVCRD) || defined(PNG_USE_PNGGCCRD))

    png_ptr->asm_flags |= PNG_ASM_FLAG_MMX_SUPPORT_COMPILED;

    if (png_mmx_support()) {
        png_ptr->asm_flags |= PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU
#    ifdef PNG_HAVE_ASSEMBLER_COMBINE_ROW
                              | PNG_ASM_FLAG_MMX_READ_COMBINE_ROW
#    endif
#    ifdef PNG_HAVE_ASSEMBLER_READ_INTERLACE
                              | PNG_ASM_FLAG_MMX_READ_INTERLACE
#    endif
#    ifndef PNG_HAVE_ASSEMBLER_READ_FILTER_ROW
                              ;
#    else
                              | 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 ;

        png_ptr->mmx_rowbytes_threshold = PNG_MMX_ROWBYTES_THRESHOLD_DEFAULT;
        png_ptr->mmx_bitdepth_threshold = PNG_MMX_BITDEPTH_THRESHOLD_DEFAULT;
#    endif
    } else {
        png_ptr->asm_flags &= ~( PNG_ASM_FLAG_MMX_SUPPORT_IN_CPU
                               | PNG_MMX_READ_FLAGS
                               | PNG_MMX_WRITE_FLAGS );
    }

#  else /* !((PNGVCRD || PNGGCCRD) && PNG_ASSEMBLER_CODE_SUPPORTED)) */

    /* clear all MMX flags; no support is compiled in */
    png_ptr->asm_flags &= ~( PNG_MMX_FLAGS );

#  endif /* ?(PNGVCRD || PNGGCCRD) */
}

#endif /* !(PNG_ASSEMBLER_CODE_SUPPORTED) */

/* this function was added to libpng 1.2.0 */
#if !defined(PNG_USE_PNGGCCRD) && \
    !(defined(PNG_ASSEMBLER_CODE_SUPPORTED) && defined(PNG_USE_PNGVCRD))
int PNGAPI
png_mmx_support(void)
{
    return -1;
}
#endif