pngget.c

一个国人自己实现图像库的程序（有参考价值）

/* pngget.c - retrieval of values from 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.)
 */

#define PNG_INTERNAL
#include "png.h"

png_uint_32 PNGAPI
png_get_valid(png_structp png_ptr, png_infop info_ptr, png_uint_32 flag)
{
   if (png_ptr != NULL && info_ptr != NULL)
      return(info_ptr->valid & flag);
   else
      return(0);
}

png_uint_32 PNGAPI
png_get_rowbytes(png_structp png_ptr, png_infop info_ptr)
{
   if (png_ptr != NULL && info_ptr != NULL)
      return(info_ptr->rowbytes);
   else
      return(0);
}

#if defined(PNG_INFO_IMAGE_SUPPORTED)
png_bytepp PNGAPI
png_get_rows(png_structp png_ptr, png_infop info_ptr)
{
   if (png_ptr != NULL && info_ptr != NULL)
      return(info_ptr->row_pointers);
   else
      return(0);
}
#endif

#ifdef PNG_EASY_ACCESS_SUPPORTED
/* easy access to info, added in libpng-0.99 */
png_uint_32 PNGAPI
png_get_image_width(png_structp png_ptr, png_infop info_ptr)
{
   if (png_ptr != NULL && info_ptr != NULL)
   {
      return info_ptr->width;
   }
   return (0);
}

png_uint_32 PNGAPI
png_get_image_height(png_structp png_ptr, png_infop info_ptr)
{
   if (png_ptr != NULL && info_ptr != NULL)
   {
      return info_ptr->height;
   }
   return (0);
}

png_byte PNGAPI
png_get_bit_depth(png_structp png_ptr, png_infop info_ptr)
{
   if (png_ptr != NULL && info_ptr != NULL)
   {
      return info_ptr->bit_depth;
   }
   return (0);
}

png_byte PNGAPI
png_get_color_type(png_structp png_ptr, png_infop info_ptr)
{
   if (png_ptr != NULL && info_ptr != NULL)
   {
      return info_ptr->color_type;
   }
   return (0);
}

png_byte PNGAPI
png_get_filter_type(png_structp png_ptr, png_infop info_ptr)
{
   if (png_ptr != NULL && info_ptr != NULL)
   {
      return info_ptr->filter_type;
   }
   return (0);
}

png_byte PNGAPI
png_get_interlace_type(png_structp png_ptr, png_infop info_ptr)
{
   if (png_ptr != NULL && info_ptr != NULL)
   {
      return info_ptr->interlace_type;
   }
   return (0);
}

png_byte PNGAPI
png_get_compression_type(png_structp png_ptr, png_infop info_ptr)
{
   if (png_ptr != NULL && info_ptr != NULL)
   {
      return info_ptr->compression_type;
   }
   return (0);
}

png_uint_32 PNGAPI
png_get_x_pixels_per_meter(png_structp png_ptr, png_infop info_ptr)
{
   if (png_ptr != NULL && info_ptr != NULL)
#if defined(PNG_pHYs_SUPPORTED)
   if (info_ptr->valid & PNG_INFO_pHYs)
   {
      png_debug1(1, "in %s retrieval function\n", "png_get_x_pixels_per_meter");
      if(info_ptr->phys_unit_type != PNG_RESOLUTION_METER)
          return (0);
      else return (info_ptr->x_pixels_per_unit);
   }
#else
   return (0);
#endif
   return (0);
}

png_uint_32 PNGAPI
png_get_y_pixels_per_meter(png_structp png_ptr, png_infop info_ptr)
{
   if (png_ptr != NULL && info_ptr != NULL)
#if defined(PNG_pHYs_SUPPORTED)
   if (info_ptr->valid & PNG_INFO_pHYs)
   {
      png_debug1(1, "in %s retrieval function\n", "png_get_y_pixels_per_meter");
      if(info_ptr->phys_unit_type != PNG_RESOLUTION_METER)
          return (0);
      else return (info_ptr->y_pixels_per_unit);
   }
#else
   return (0);
#endif
   return (0);
}

png_uint_32 PNGAPI
png_get_pixels_per_meter(png_structp png_ptr, png_infop info_ptr)
{
   if (png_ptr != NULL && info_ptr != NULL)
#if defined(PNG_pHYs_SUPPORTED)
   if (info_ptr->valid & PNG_INFO_pHYs)
   {
      png_debug1(1, "in %s retrieval function\n", "png_get_pixels_per_meter");
      if(info_ptr->phys_unit_type != PNG_RESOLUTION_METER ||
         info_ptr->x_pixels_per_unit != info_ptr->y_pixels_per_unit)
          return (0);
      else return (info_ptr->x_pixels_per_unit);
   }
#else
   return (0);
#endif
   return (0);
}

#ifdef PNG_FLOATING_POINT_SUPPORTED
float PNGAPI
png_get_pixel_aspect_ratio(png_structp png_ptr, png_infop info_ptr)
   {
   if (png_ptr != NULL && info_ptr != NULL)
#if defined(PNG_pHYs_SUPPORTED)
   if (info_ptr->valid & PNG_INFO_pHYs)
   {
      png_debug1(1, "in %s retrieval function\n", "png_get_aspect_ratio");
      if (info_ptr->x_pixels_per_unit == 0)
         return ((float)0.0);
      else
         return ((float)((float)info_ptr->y_pixels_per_unit
            /(float)info_ptr->x_pixels_per_unit));
   }
#else
   return (0.0);
#endif
   return ((float)0.0);
}
#endif

png_int_32 PNGAPI
png_get_x_offset_microns(png_structp png_ptr, png_infop info_ptr)
{
   if (png_ptr != NULL && info_ptr != NULL)
#if defined(PNG_oFFs_SUPPORTED)
   if (info_ptr->valid & PNG_INFO_oFFs)
   {
      png_debug1(1, "in %s retrieval function\n", "png_get_x_offset_microns");
      if(info_ptr->offset_unit_type != PNG_OFFSET_MICROMETER)
          return (0);
      else return (info_ptr->x_offset);
   }
#else
   return (0);
#endif
   return (0);
}

png_int_32 PNGAPI
png_get_y_offset_microns(png_structp png_ptr, png_infop info_ptr)
{
   if (png_ptr != NULL && info_ptr != NULL)
#if defined(PNG_oFFs_SUPPORTED)
   if (info_ptr->valid & PNG_INFO_oFFs)
   {
      png_debug1(1, "in %s retrieval function\n", "png_get_y_offset_microns");
      if(info_ptr->offset_unit_type != PNG_OFFSET_MICROMETER)
          return (0);
      else return (info_ptr->y_offset);
   }
#else
   return (0);
#endif
   return (0);
}

png_int_32 PNGAPI
png_get_x_offset_pixels(png_structp png_ptr, png_infop info_ptr)
{
   if (png_ptr != NULL && info_ptr != NULL)
#if defined(PNG_oFFs_SUPPORTED)
   if (info_ptr->valid & PNG_INFO_oFFs)
   {
      png_debug1(1, "in %s retrieval function\n", "png_get_x_offset_microns");
      if(info_ptr->offset_unit_type != PNG_OFFSET_PIXEL)
          return (0);
      else return (info_ptr->x_offset);
   }
#else
   return (0);
#endif
   return (0);
}

png_int_32 PNGAPI
png_get_y_offset_pixels(png_structp png_ptr, png_infop info_ptr)
{
   if (png_ptr != NULL && info_ptr != NULL)
#if defined(PNG_oFFs_SUPPORTED)
   if (info_ptr->valid & PNG_INFO_oFFs)
   {
      png_debug1(1, "in %s retrieval function\n", "png_get_y_offset_microns");
      if(info_ptr->offset_unit_type != PNG_OFFSET_PIXEL)
          return (0);
      else return (info_ptr->y_offset);
   }
#else
   return (0);
#endif
   return (0);
}

#if defined(PNG_INCH_CONVERSIONS) && defined(PNG_FLOATING_POINT_SUPPORTED)
png_uint_32 PNGAPI
png_get_pixels_per_inch(png_structp png_ptr, png_infop info_ptr)
{
   return ((png_uint_32)((float)png_get_pixels_per_meter(png_ptr, info_ptr)
     *.0254 +.5));
}

png_uint_32 PNGAPI
png_get_x_pixels_per_inch(png_structp png_ptr, png_infop info_ptr)
{
   return ((png_uint_32)((float)png_get_x_pixels_per_meter(png_ptr, info_ptr)
     *.0254 +.5));
}

png_uint_32 PNGAPI
png_get_y_pixels_per_inch(png_structp png_ptr, png_infop info_ptr)
{
   return ((png_uint_32)((float)png_get_y_pixels_per_meter(png_ptr, info_ptr)
     *.0254 +.5));
}

float PNGAPI
png_get_x_offset_inches(png_structp png_ptr, png_infop info_ptr)
{
   return ((float)png_get_x_offset_microns(png_ptr, info_ptr)
     *.00003937);
}

float PNGAPI
png_get_y_offset_inches(png_structp png_ptr, png_infop info_ptr)
{
   return ((float)png_get_y_offset_microns(png_ptr, info_ptr)
     *.00003937);
}

#if defined(PNG_pHYs_SUPPORTED)
png_uint_32 PNGAPI
png_get_pHYs_dpi(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;
         if(*unit_type == 1)
         {
            if (res_x != NULL) *res_x = (png_uint_32)(*res_x * .0254 + .50);
            if (res_y != NULL) *res_y = (png_uint_32)(*res_y * .0254 + .50);
         }
      }
   }
   return (retval);
}
#endif /* PNG_pHYs_SUPPORTED */
#endif  /* PNG_INCH_CONVERSIONS && PNG_FLOATING_POINT_SUPPORTED */

/* png_get_channels really belongs in here, too, but it's been around longer */

#endif  /* PNG_EASY_ACCESS_SUPPORTED */

png_byte PNGAPI
png_get_channels(png_structp png_ptr, png_infop info_ptr)
{
   if (png_ptr != NULL && info_ptr != NULL)
      return(info_ptr->channels);
   else
      return (0);
}

png_bytep PNGAPI
png_get_signature(png_structp png_ptr, png_infop info_ptr)
{
   if (png_ptr != NULL && info_ptr != NULL)
      return(info_ptr->signature);
   else
      return (NULL);
}

#if defined(PNG_bKGD_SUPPORTED)
png_uint_32 PNGAPI
png_get_bKGD(png_structp png_ptr, png_infop info_ptr,
   png_color_16p *background)
{
   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_bKGD)
      && background != NULL)
   {
      png_debug1(1, "in %s retrieval function\n", "bKGD");
      *background = &(info_ptr->background);
      return (PNG_INFO_bKGD);
   }
   return (0);
}
#endif

#if defined(PNG_cHRM_SUPPORTED)
#ifdef PNG_FLOATING_POINT_SUPPORTED
png_uint_32 PNGAPI
png_get_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)
{
   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM))
   {
      png_debug1(1, "in %s retrieval function\n", "cHRM");
      if (white_x != NULL)
         *white_x = (double)info_ptr->x_white;
      if (white_y != NULL)
         *white_y = (double)info_ptr->y_white;
      if (red_x != NULL)
         *red_x = (double)info_ptr->x_red;
      if (red_y != NULL)
         *red_y = (double)info_ptr->y_red;
      if (green_x != NULL)
         *green_x = (double)info_ptr->x_green;
      if (green_y != NULL)
         *green_y = (double)info_ptr->y_green;
      if (blue_x != NULL)
         *blue_x = (double)info_ptr->x_blue;
      if (blue_y != NULL)
         *blue_y = (double)info_ptr->y_blue;
      return (PNG_INFO_cHRM);
   }
   return (0);
}
#endif
#ifdef PNG_FIXED_POINT_SUPPORTED
png_uint_32 PNGAPI
png_get_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)
{
   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_cHRM))
   {
      png_debug1(1, "in %s retrieval function\n", "cHRM");
      if (white_x != NULL)
         *white_x = info_ptr->int_x_white;
      if (white_y != NULL)
         *white_y = info_ptr->int_y_white;
      if (red_x != NULL)
         *red_x = info_ptr->int_x_red;
      if (red_y != NULL)
         *red_y = info_ptr->int_y_red;
      if (green_x != NULL)
         *green_x = info_ptr->int_x_green;
      if (green_y != NULL)
         *green_y = info_ptr->int_y_green;
      if (blue_x != NULL)
         *blue_x = info_ptr->int_x_blue;
      if (blue_y != NULL)
         *blue_y = info_ptr->int_y_blue;
      return (PNG_INFO_cHRM);
   }
   return (0);
}
#endif
#endif

#if defined(PNG_gAMA_SUPPORTED)
#ifdef PNG_FLOATING_POINT_SUPPORTED
png_uint_32 PNGAPI
png_get_gAMA(png_structp png_ptr, png_infop info_ptr, double *file_gamma)
{
   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA)
      && file_gamma != NULL)
   {
      png_debug1(1, "in %s retrieval function\n", "gAMA");
      *file_gamma = (double)info_ptr->gamma;
      return (PNG_INFO_gAMA);
   }
   return (0);
}
#endif
#ifdef PNG_FIXED_POINT_SUPPORTED
png_uint_32 PNGAPI
png_get_gAMA_fixed(png_structp png_ptr, png_infop info_ptr,
    png_fixed_point *int_file_gamma)
{
   if (png_ptr != NULL && info_ptr != NULL && (info_ptr->valid & PNG_INFO_gAMA)
      && int_file_gamma != NULL)