pngget.c

一个国人自己实现图像库的程序（有参考价值）

   {
      png_debug1(1, "in %s retrieval function\n", "gAMA");
      *int_file_gamma = info_ptr->int_gamma;
      return (PNG_INFO_gAMA);
   }
   return (0);
}
#endif
#endif

#if defined(PNG_sRGB_SUPPORTED)
png_uint_32 PNGAPI
png_get_sRGB(png_structp png_ptr, png_infop info_ptr, int *file_srgb_intent)
{
   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_sRGB)
      && file_srgb_intent != NULL)
   {
      png_debug1(1, "in %s retrieval function\n", "sRGB");
      *file_srgb_intent = (int)info_ptr->srgb_intent;
      return (PNG_INFO_sRGB);
   }
   return (0);
}
#endif

#if defined(PNG_iCCP_SUPPORTED)
png_uint_32 PNGAPI
png_get_iCCP(png_structp png_ptr, png_infop info_ptr,
             png_charpp name, int *compression_type,
             png_charpp profile, png_uint_32 *proflen)
{
   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_iCCP)
      && name != NULL && profile != NULL && proflen != NULL)
   {
      png_debug1(1, "in %s retrieval function\n", "iCCP");
      *name = info_ptr->iccp_name;
      *profile = info_ptr->iccp_profile;
      /* compression_type is a dummy so the API won't have to change
         if we introduce multiple compression types later. */
      *proflen = (int)info_ptr->iccp_proflen;
      *compression_type = (int)info_ptr->iccp_compression;
      return (PNG_INFO_iCCP);
   }
   return (0);
}
#endif

#if defined(PNG_sPLT_SUPPORTED)
png_uint_32 PNGAPI
png_get_sPLT(png_structp png_ptr, png_infop info_ptr,
             png_sPLT_tpp spalettes)
{
   if (png_ptr != NULL && info_ptr != NULL && spalettes != NULL)
     *spalettes = info_ptr->splt_palettes;
   return ((png_uint_32)info_ptr->splt_palettes_num);
}
#endif

#if defined(PNG_hIST_SUPPORTED)
png_uint_32 PNGAPI
png_get_hIST(png_structp png_ptr, png_infop info_ptr, png_uint_16p *hist)
{
   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_hIST)
      && hist != NULL)
   {
      png_debug1(1, "in %s retrieval function\n", "hIST");
      *hist = info_ptr->hist;
      return (PNG_INFO_hIST);
   }
   return (0);
}
#endif

png_uint_32 PNGAPI
png_get_IHDR(png_structp png_ptr, png_infop info_ptr,
   png_uint_32 *width, png_uint_32 *height, int *bit_depth,
   int *color_type, int *interlace_type, int *compression_type,
   int *filter_type)

{
   if (png_ptr != NULL && info_ptr != NULL && width != NULL && height != NULL &&
      bit_depth != NULL && color_type != NULL)
   {
      int pixel_depth, channels;
      png_uint_32 rowbytes_per_pixel;

      png_debug1(1, "in %s retrieval function\n", "IHDR");
      *width = info_ptr->width;
      *height = info_ptr->height;
      *bit_depth = info_ptr->bit_depth;
      *color_type = info_ptr->color_type;
      if (compression_type != NULL)
         *compression_type = info_ptr->compression_type;
      if (filter_type != NULL)
         *filter_type = info_ptr->filter_type;
      if (interlace_type != NULL)
         *interlace_type = info_ptr->interlace_type;

      /* check for potential overflow of rowbytes */
      if (*color_type == PNG_COLOR_TYPE_PALETTE)
         channels = 1;
      else if (*color_type & PNG_COLOR_MASK_COLOR)
         channels = 3;
      else
         channels = 1;
      if (*color_type & PNG_COLOR_MASK_ALPHA)
         channels++;
      pixel_depth = *bit_depth * channels;
      rowbytes_per_pixel = (pixel_depth + 7) >> 3;
      if ((*width > PNG_MAX_UINT/rowbytes_per_pixel))
      {
         png_warning(png_ptr,
            "Width too large for libpng to process image data.");
      }
      return (1);
   }
   return (0);
}

#if defined(PNG_oFFs_SUPPORTED)
png_uint_32 PNGAPI
png_get_oFFs(png_structp png_ptr, png_infop info_ptr,
   png_int_32 *offset_x, png_int_32 *offset_y, int *unit_type)
{
   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_oFFs)
      && offset_x != NULL && offset_y != NULL && unit_type != NULL)
   {
      png_debug1(1, "in %s retrieval function\n", "oFFs");
      *offset_x = info_ptr->x_offset;
      *offset_y = info_ptr->y_offset;
      *unit_type = (int)info_ptr->offset_unit_type;
      return (PNG_INFO_oFFs);
   }
   return (0);
}
#endif

#if defined(PNG_pCAL_SUPPORTED)
png_uint_32 PNGAPI
png_get_pCAL(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)
{
   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_pCAL)
      && purpose != NULL && X0 != NULL && X1 != NULL && type != NULL &&
      nparams != NULL && units != NULL && params != NULL)
   {
      png_debug1(1, "in %s retrieval function\n", "pCAL");
      *purpose = info_ptr->pcal_purpose;
      *X0 = info_ptr->pcal_X0;
      *X1 = info_ptr->pcal_X1;
      *type = (int)info_ptr->pcal_type;
      *nparams = (int)info_ptr->pcal_nparams;
      *units = info_ptr->pcal_units;
      *params = info_ptr->pcal_params;
      return (PNG_INFO_pCAL);
   }
   return (0);
}
#endif

#if defined(PNG_sCAL_SUPPORTED)
#ifdef PNG_FLOATING_POINT_SUPPORTED
png_uint_32 PNGAPI
png_get_sCAL(png_structp png_ptr, png_infop info_ptr,
             int *unit, double *width, double *height)
{
    if (png_ptr != NULL && info_ptr != NULL &&
       (info_ptr->valid & PNG_INFO_sCAL))
    {
        *unit = info_ptr->scal_unit;
        *width = info_ptr->scal_pixel_width;
        *height = info_ptr->scal_pixel_height;
        return (PNG_INFO_sCAL);
    }
    return(0);
}
#else
#ifdef PNG_FIXED_POINT_SUPPORTED
png_uint_32 PNGAPI
png_get_sCAL_s(png_structp png_ptr, png_infop info_ptr,
             int *unit, png_charpp width, png_charpp height)
{
    if (png_ptr != NULL && info_ptr != NULL &&
       (info_ptr->valid & PNG_INFO_sCAL))
    {
        *unit = info_ptr->scal_unit;
        *width = info_ptr->scal_s_width;
        *height = info_ptr->scal_s_height;
        return (PNG_INFO_sCAL);
    }
    return(0);
}
#endif
#endif
#endif

#if defined(PNG_pHYs_SUPPORTED)
png_uint_32 PNGAPI
png_get_pHYs(png_structp png_ptr, png_infop info_ptr,
   png_uint_32 *res_x, png_uint_32 *res_y, int *unit_type)
{
   png_uint_32 retval = 0;

   if (png_ptr != NULL && info_ptr != NULL &&
      (info_ptr->valid & PNG_INFO_pHYs))
   {
      png_debug1(1, "in %s retrieval function\n", "pHYs");
      if (res_x != NULL)
      {
         *res_x = info_ptr->x_pixels_per_unit;
         retval |= PNG_INFO_pHYs;
      }
      if (res_y != NULL)
      {
         *res_y = info_ptr->y_pixels_per_unit;
         retval |= PNG_INFO_pHYs;
      }
      if (unit_type != NULL)
      {
         *unit_type = (int)info_ptr->phys_unit_type;
         retval |= PNG_INFO_pHYs;
      }
   }
   return (retval);
}
#endif

png_uint_32 PNGAPI
png_get_PLTE(png_structp png_ptr, png_infop info_ptr, png_colorp *palette,
   int *num_palette)
{
   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_PLTE)
       && palette != NULL)
   {
      png_debug1(1, "in %s retrieval function\n", "PLTE");
      *palette = info_ptr->palette;
      *num_palette = info_ptr->num_palette;
      png_debug1(3, "num_palette = %d\n", *num_palette);
      return (PNG_INFO_PLTE);
   }
   return (0);
}

#if defined(PNG_sBIT_SUPPORTED)
png_uint_32 PNGAPI
png_get_sBIT(png_structp png_ptr, png_infop info_ptr, png_color_8p *sig_bit)
{
   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_sBIT)
      && sig_bit != NULL)
   {
      png_debug1(1, "in %s retrieval function\n", "sBIT");
      *sig_bit = &(info_ptr->sig_bit);
      return (PNG_INFO_sBIT);
   }
   return (0);
}
#endif

#if defined(PNG_TEXT_SUPPORTED)
png_uint_32 PNGAPI
png_get_text(png_structp png_ptr, png_infop info_ptr, png_textp *text_ptr,
   int *num_text)
{
   if (png_ptr != NULL && info_ptr != NULL && info_ptr->num_text > 0)
   {
      png_debug1(1, "in %s retrieval function\n",
         (png_ptr->chunk_name[0] == '\0' ? "text"
             : (png_const_charp)png_ptr->chunk_name));
      if (text_ptr != NULL)
         *text_ptr = info_ptr->text;
      if (num_text != NULL)
         *num_text = info_ptr->num_text;
      return ((png_uint_32)info_ptr->num_text);
   }
   if (num_text != NULL)
     *num_text = 0;
   return(0);
}
#endif

#if defined(PNG_tIME_SUPPORTED)
png_uint_32 PNGAPI
png_get_tIME(png_structp png_ptr, png_infop info_ptr, png_timep *mod_time)
{
   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_tIME)
       && mod_time != NULL)
   {
      png_debug1(1, "in %s retrieval function\n", "tIME");
      *mod_time = &(info_ptr->mod_time);
      return (PNG_INFO_tIME);
   }
   return (0);
}
#endif

#if defined(PNG_tRNS_SUPPORTED)
png_uint_32 PNGAPI
png_get_tRNS(png_structp png_ptr, png_infop info_ptr,
   png_bytep *trans, int *num_trans, png_color_16p *trans_values)
{
   png_uint_32 retval = 0;
   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_tRNS))
   {
      png_debug1(1, "in %s retrieval function\n", "tRNS");
      if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
      {
          if (trans != NULL)
          {
             *trans = info_ptr->trans;
             retval |= PNG_INFO_tRNS;
          }
          if (trans_values != NULL)
             *trans_values = &(info_ptr->trans_values);
      }
      else /* if (info_ptr->color_type != PNG_COLOR_TYPE_PALETTE) */
      {
          if (trans_values != NULL)
          {
             *trans_values = &(info_ptr->trans_values);
             retval |= PNG_INFO_tRNS;
          }
          if(trans != NULL)
             *trans = NULL;
      }
      if(num_trans != NULL)
      {
         *num_trans = info_ptr->num_trans;
         retval |= PNG_INFO_tRNS;
      }
   }
   return (retval);
}
#endif

#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)
png_uint_32 PNGAPI
png_get_unknown_chunks(png_structp png_ptr, png_infop info_ptr,
             png_unknown_chunkpp unknowns)
{
   if (png_ptr != NULL && info_ptr != NULL && unknowns != NULL)
     *unknowns = info_ptr->unknown_chunks;
   return ((png_uint_32)info_ptr->unknown_chunks_num);
}
#endif

#if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
png_byte PNGAPI
png_get_rgb_to_gray_status (png_structp png_ptr)
{
   return (png_byte)(png_ptr? png_ptr->rgb_to_gray_status : 0);
}
#endif

#if defined(PNG_USER_CHUNKS_SUPPORTED)
png_voidp PNGAPI
png_get_user_chunk_ptr(png_structp png_ptr)
{
   return (png_ptr? png_ptr->user_chunk_ptr : NULL);
}
#endif


png_uint_32 PNGAPI
png_get_compression_buffer_size(png_structp png_ptr)
{
   return (png_uint_32)(png_ptr? png_ptr->zbuf_size : 0L);
}


#ifdef PNG_ASSEMBLER_CODE_SUPPORTED
/* this function was added to libpng 1.2.0 and should exist by default*/
png_uint_32 PNGAPI
png_get_asm_flags (png_structp png_ptr)
{
    return (png_uint_32)(png_ptr? png_ptr->asm_flags : 0L);
}

/* this function was added to libpng 1.2.0 and should exist by default */
png_uint_32 PNGAPI
png_get_asm_flagmask (int flag_select)
{
    png_uint_32 settable_asm_flags = 0;

    if (flag_select & PNG_SELECT_READ)
        settable_asm_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 ;
          /* no non-MMX flags yet */

#if 0
    /* GRR:  no write-flags yet, either, but someday... */
    if (flag_select & PNG_SELECT_WRITE)
        settable_asm_flags |=
          PNG_ASM_FLAG_MMX_WRITE_ [whatever] ;
#endif /* 0 */

    return settable_asm_flags;  /* _theoretically_ settable capabilities only */
}
#endif /* PNG_ASSEMBLER_CODE_SUPPORTED */


#if defined(PNG_ASSEMBLER_CODE_SUPPORTED)
    /* GRR:  could add this:   && defined(PNG_MMX_CODE_SUPPORTED) */
/* this function was added to libpng 1.2.0 */
png_uint_32 PNGAPI
png_get_mmx_flagmask (int flag_select, int *compilerID)
{
    png_uint_32 settable_mmx_flags = 0;

    if (flag_select & PNG_SELECT_READ)
        settable_mmx_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 ;
#if 0
    /* GRR:  no MMX write support yet, but someday... */
    if (flag_select & PNG_SELECT_WRITE)
        settable_mmx_flags |=
          PNG_ASM_FLAG_MMX_WRITE_ [whatever] ;
#endif /* 0 */

    if (compilerID != NULL) {
#ifdef PNG_USE_PNGVCRD
        *compilerID = 1;    /* MSVC */
#else
#ifdef PNG_USE_PNGGCCRD
        *compilerID = 2;    /* gcc/gas */
#else
        *compilerID = -1;   /* unknown (i.e., no asm/MMX code compiled) */
#endif
#endif
    }

    return settable_mmx_flags;  /* _theoretically_ settable capabilities only */
}

/* this function was added to libpng 1.2.0 */
png_byte PNGAPI
png_get_mmx_bitdepth_threshold (png_structp png_ptr)
{
    return (png_byte)(png_ptr? png_ptr->mmx_bitdepth_threshold : 0);
}

/* this function was added to libpng 1.2.0 */
png_uint_32 PNGAPI
png_get_mmx_rowbytes_threshold (png_structp png_ptr)
{
    return (png_uint_32)(png_ptr? png_ptr->mmx_rowbytes_threshold : 0L);
}
#endif /* PNG_ASSEMBLER_CODE_SUPPORTED */