pngset.c

一个国人自己实现图像库的程序（有参考价值）

/* pngset.c - storage of image information into info struct
 *
 * 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.)
 *
 * The functions here are used during reads to store data from the file
 * into the info struct, and during writes to store application data
 * into the info struct for writing into the file.  This abstracts the
 * info struct and allows us to change the structure in the future.
 */

#define PNG_INTERNAL
#include "png.h"

#if defined(PNG_bKGD_SUPPORTED)
void PNGAPI
png_set_bKGD(png_structp png_ptr, png_infop info_ptr, png_color_16p background)
{
   png_debug1(1, "in %s storage function\n", "bKGD");
   if (png_ptr == NULL || info_ptr == NULL)
      return;

   png_memcpy(&(info_ptr->background), background, sizeof(png_color_16));
   info_ptr->valid |= PNG_INFO_bKGD;
}
#endif

#if defined(PNG_cHRM_SUPPORTED)
#ifdef PNG_FLOATING_POINT_SUPPORTED
void PNGAPI
png_set_cHRM(png_structp png_ptr, png_infop info_ptr,
   double white_x, double white_y, double red_x, double red_y,
   double green_x, double green_y, double blue_x, double blue_y)
{
   png_debug1(1, "in %s storage function\n", "cHRM");
   if (png_ptr == NULL || info_ptr == NULL)
      return;

   info_ptr->x_white = (float)white_x;
   info_ptr->y_white = (float)white_y;
   info_ptr->x_red   = (float)red_x;
   info_ptr->y_red   = (float)red_y;
   info_ptr->x_green = (float)green_x;
   info_ptr->y_green = (float)green_y;
   info_ptr->x_blue  = (float)blue_x;
   info_ptr->y_blue  = (float)blue_y;
#ifdef PNG_FIXED_POINT_SUPPORTED
   info_ptr->int_x_white = (png_fixed_point)(white_x*100000.+0.5);
   info_ptr->int_y_white = (png_fixed_point)(white_y*100000.+0.5);
   info_ptr->int_x_red   = (png_fixed_point)(red_x*100000.+0.5);
   info_ptr->int_y_red   = (png_fixed_point)(red_y*100000.+0.5);
   info_ptr->int_x_green = (png_fixed_point)(green_x*100000.+0.5);
   info_ptr->int_y_green = (png_fixed_point)(green_y*100000.+0.5);
   info_ptr->int_x_blue  = (png_fixed_point)(blue_x*100000.+0.5);
   info_ptr->int_y_blue  = (png_fixed_point)(blue_y*100000.+0.5);
#endif
   info_ptr->valid |= PNG_INFO_cHRM;
}
#endif
#ifdef PNG_FIXED_POINT_SUPPORTED
void PNGAPI
png_set_cHRM_fixed(png_structp png_ptr, png_infop info_ptr,
   png_fixed_point white_x, png_fixed_point white_y, png_fixed_point red_x,
   png_fixed_point red_y, png_fixed_point green_x, png_fixed_point green_y,
   png_fixed_point blue_x, png_fixed_point blue_y)
{
   png_debug1(1, "in %s storage function\n", "cHRM");
   if (png_ptr == NULL || info_ptr == NULL)
      return;

   info_ptr->int_x_white = white_x;
   info_ptr->int_y_white = white_y;
   info_ptr->int_x_red   = red_x;
   info_ptr->int_y_red   = red_y;
   info_ptr->int_x_green = green_x;
   info_ptr->int_y_green = green_y;
   info_ptr->int_x_blue  = blue_x;
   info_ptr->int_y_blue  = blue_y;
#ifdef PNG_FLOATING_POINT_SUPPORTED
   info_ptr->x_white = (float)(white_x/100000.);
   info_ptr->y_white = (float)(white_y/100000.);
   info_ptr->x_red   = (float)(red_x/100000.);
   info_ptr->y_red   = (float)(red_y/100000.);
   info_ptr->x_green = (float)(green_x/100000.);
   info_ptr->y_green = (float)(green_y/100000.);
   info_ptr->x_blue  = (float)(blue_x/100000.);
   info_ptr->y_blue  = (float)(blue_y/100000.);
#endif
   info_ptr->valid |= PNG_INFO_cHRM;
}
#endif
#endif

#if defined(PNG_gAMA_SUPPORTED)
#ifdef PNG_FLOATING_POINT_SUPPORTED
void PNGAPI
png_set_gAMA(png_structp png_ptr, png_infop info_ptr, double file_gamma)
{
   png_debug1(1, "in %s storage function\n", "gAMA");
   if (png_ptr == NULL || info_ptr == NULL)
      return;

   info_ptr->gamma = (float)file_gamma;
#ifdef PNG_FIXED_POINT_SUPPORTED
   info_ptr->int_gamma = (int)(file_gamma*100000.+.5);
#endif
   info_ptr->valid |= PNG_INFO_gAMA;
   if(file_gamma == 0.0)
      png_warning(png_ptr, "Setting gamma=0");
}
#endif
void PNGAPI
png_set_gAMA_fixed(png_structp png_ptr, png_infop info_ptr, png_fixed_point
   int_gamma)
{
   png_debug1(1, "in %s storage function\n", "gAMA");
   if (png_ptr == NULL || info_ptr == NULL)
      return;

#ifdef PNG_FLOATING_POINT_SUPPORTED
   info_ptr->gamma = (float)(int_gamma/100000.);
#endif
#ifdef PNG_FIXED_POINT_SUPPORTED
   info_ptr->int_gamma = int_gamma;
#endif
   info_ptr->valid |= PNG_INFO_gAMA;
   if(int_gamma == 0)
      png_warning(png_ptr, "Setting gamma=0");
}
#endif

#if defined(PNG_hIST_SUPPORTED)
void PNGAPI
png_set_hIST(png_structp png_ptr, png_infop info_ptr, png_uint_16p hist)
{
   int	i;

   png_debug1(1, "in %s storage function\n", "hIST");
   if (png_ptr == NULL || info_ptr == NULL)
      return;
   if (info_ptr->num_palette == 0)
   {
       png_warning(png_ptr,
          "Palette size 0, hIST allocation skipped.");
       return;
   }

#ifdef PNG_FREE_ME_SUPPORTED
   png_free_data(png_ptr, info_ptr, PNG_FREE_HIST, 0);
#endif
   /* Changed from info->num_palette to 256 in version 1.2.1 */
   png_ptr->hist = (png_uint_16p)png_malloc(png_ptr,
      (png_uint_32)(256 * sizeof (png_uint_16)));

   for (i = 0; i < info_ptr->num_palette; i++)
       png_ptr->hist[i] = hist[i];
   info_ptr->hist = png_ptr->hist;
   info_ptr->valid |= PNG_INFO_hIST;

#ifdef PNG_FREE_ME_SUPPORTED
   info_ptr->free_me |= PNG_FREE_HIST;
#else
   png_ptr->flags |= PNG_FLAG_FREE_HIST;
#endif
}
#endif

void PNGAPI
png_set_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)
{
   int rowbytes_per_pixel;
   png_debug1(1, "in %s storage function\n", "IHDR");
   if (png_ptr == NULL || info_ptr == NULL)
      return;

   /* check for width and height valid values */
   if (width == 0 || height == 0)
      png_error(png_ptr, "Image width or height is zero in IHDR");
   if (width > PNG_MAX_UINT || height > PNG_MAX_UINT)
      png_error(png_ptr, "Invalid image size in IHDR");

   /* check other values */
   if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 &&
      bit_depth != 8 && bit_depth != 16)
      png_error(png_ptr, "Invalid bit depth in IHDR");

   if (color_type < 0 || color_type == 1 ||
      color_type == 5 || color_type > 6)
      png_error(png_ptr, "Invalid color type in IHDR");

   if (((color_type == PNG_COLOR_TYPE_PALETTE) && bit_depth > 8) ||
       ((color_type == PNG_COLOR_TYPE_RGB ||
         color_type == PNG_COLOR_TYPE_GRAY_ALPHA ||
         color_type == PNG_COLOR_TYPE_RGB_ALPHA) && bit_depth < 8))
      png_error(png_ptr, "Invalid color type/bit depth combination in IHDR");

   if (interlace_type >= PNG_INTERLACE_LAST)
      png_error(png_ptr, "Unknown interlace method in IHDR");

   if (compression_type != PNG_COMPRESSION_TYPE_BASE)
      png_error(png_ptr, "Unknown compression method in IHDR");

#if defined(PNG_MNG_FEATURES_SUPPORTED)
   /* Accept filter_method 64 (intrapixel differencing) only if
    * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
    * 2. Libpng did not read a PNG signature (this filter_method is only
    *    used in PNG datastreams that are embedded in MNG datastreams) and
    * 3. The application called png_permit_mng_features with a mask that
    *    included PNG_FLAG_MNG_FILTER_64 and
    * 4. The filter_method is 64 and
    * 5. The color_type is RGB or RGBA
    */
   if((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE)&&png_ptr->mng_features_permitted)
      png_warning(png_ptr,"MNG features are not allowed in a PNG datastream\n");
   if(filter_type != PNG_FILTER_TYPE_BASE)
   {
     if(!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
        (filter_type == PNG_INTRAPIXEL_DIFFERENCING) &&
        ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) == 0) &&
        (color_type == PNG_COLOR_TYPE_RGB || 
         color_type == PNG_COLOR_TYPE_RGB_ALPHA)))
        png_error(png_ptr, "Unknown filter method in IHDR");
     if(png_ptr->mode&PNG_HAVE_PNG_SIGNATURE)
        png_warning(png_ptr, "Invalid filter method in IHDR");
   }
#else
   if(filter_type != PNG_FILTER_TYPE_BASE)
      png_error(png_ptr, "Unknown filter method in IHDR");
#endif

   info_ptr->width = width;
   info_ptr->height = height;
   info_ptr->bit_depth = (png_byte)bit_depth;
   info_ptr->color_type =(png_byte) color_type;
   info_ptr->compression_type = (png_byte)compression_type;
   info_ptr->filter_type = (png_byte)filter_type;
   info_ptr->interlace_type = (png_byte)interlace_type;
   if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
      info_ptr->channels = 1;
   else if (info_ptr->color_type & PNG_COLOR_MASK_COLOR)
      info_ptr->channels = 3;
   else
      info_ptr->channels = 1;
   if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA)
      info_ptr->channels++;
   info_ptr->pixel_depth = (png_byte)(info_ptr->channels * info_ptr->bit_depth);

   /* check for overflow */
   rowbytes_per_pixel = (info_ptr->pixel_depth + 7) >> 3;
   if (( width > PNG_MAX_UINT/rowbytes_per_pixel))
   {
      png_warning(png_ptr,
         "Width too large to process image data; rowbytes will overflow.");
      info_ptr->rowbytes = (png_size_t)0;
   }
   else
      info_ptr->rowbytes = (info_ptr->width * info_ptr->pixel_depth + 7) >> 3;
}

#if defined(PNG_oFFs_SUPPORTED)
void PNGAPI
png_set_oFFs(png_structp png_ptr, png_infop info_ptr,
   png_int_32 offset_x, png_int_32 offset_y, int unit_type)
{
   png_debug1(1, "in %s storage function\n", "oFFs");
   if (png_ptr == NULL || info_ptr == NULL)
      return;

   info_ptr->x_offset = offset_x;
   info_ptr->y_offset = offset_y;
   info_ptr->offset_unit_type = (png_byte)unit_type;
   info_ptr->valid |= PNG_INFO_oFFs;
}
#endif

#if defined(PNG_pCAL_SUPPORTED)
void PNGAPI
png_set_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)
{
   png_uint_32 length;
   int i;

   png_debug1(1, "in %s storage function\n", "pCAL");
   if (png_ptr == NULL || info_ptr == NULL)
      return;

   length = png_strlen(purpose) + 1;
   png_debug1(3, "allocating purpose for info (%lu bytes)\n", length);
   info_ptr->pcal_purpose = (png_charp)png_malloc(png_ptr, length);
   png_memcpy(info_ptr->pcal_purpose, purpose, (png_size_t)length);

   png_debug(3, "storing X0, X1, type, and nparams in info\n");
   info_ptr->pcal_X0 = X0;
   info_ptr->pcal_X1 = X1;
   info_ptr->pcal_type = (png_byte)type;
   info_ptr->pcal_nparams = (png_byte)nparams;

   length = png_strlen(units) + 1;
   png_debug1(3, "allocating units for info (%lu bytes)\n", length);
   info_ptr->pcal_units = (png_charp)png_malloc(png_ptr, length);
   png_memcpy(info_ptr->pcal_units, units, (png_size_t)length);

   info_ptr->pcal_params = (png_charpp)png_malloc(png_ptr,
      (png_uint_32)((nparams + 1) * sizeof(png_charp)));

   info_ptr->pcal_params[nparams] = NULL;

   for (i = 0; i < nparams; i++)
   {
      length = png_strlen(params[i]) + 1;
      png_debug2(3, "allocating parameter %d for info (%lu bytes)\n", i, length);
      info_ptr->pcal_params[i] = (png_charp)png_malloc(png_ptr, length);
      png_memcpy(info_ptr->pcal_params[i], params[i], (png_size_t)length);
   }

   info_ptr->valid |= PNG_INFO_pCAL;
#ifdef PNG_FREE_ME_SUPPORTED
   info_ptr->free_me |= PNG_FREE_PCAL;
#endif
}
#endif

#if defined(PNG_READ_sCAL_SUPPORTED) || defined(PNG_WRITE_sCAL_SUPPORTED)
#ifdef PNG_FLOATING_POINT_SUPPORTED
void PNGAPI
png_set_sCAL(png_structp png_ptr, png_infop info_ptr,
             int unit, double width, double height)
{
   png_debug1(1, "in %s storage function\n", "sCAL");
   if (png_ptr == NULL || info_ptr == NULL)
      return;

   info_ptr->scal_unit = (png_byte)unit;
   info_ptr->scal_pixel_width = width;
   info_ptr->scal_pixel_height = height;