/*- pngtopng

 *

 * COPYRIGHT: Written by John Cunningham Bowler, 2011.

 * To the extent possible under law, the author has waived all copyright and

 * related or neighboring rights to this work.  This work is published from:

 * United States.

 *

 * Read a PNG and write it out in a fixed format, using the 'simplified API'

 * that was introduced in libpng-1.6.0.

 *

 * This sample code is just the code from the top of 'example.c' with some error

 * handling added.  See example.c for more comments.

 */

#include <stddef.h></stddef.h>

#include <stdlib.h></stdlib.h>

#include <string.h></string.h>

#include <stdio.h></stdio.h>

/* Normally use <png.h> here to get the installed libpng, but this is done to</png.h>

 * ensure the code picks up the local libpng implementation:

 */

#include "../../png.h"

#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && \

    defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)

int main(int argc, const char **argv)

{

   int result = 1;

   if (argc == 3)

   {

      png_image image;

      /* Only the image structure version number needs to be set. */

      memset(&image, 0, sizeof image);

      image.version = PNG_IMAGE_VERSION;

      if (png_image_begin_read_from_file(&image, argv[1]))

      {

         png_bytep buffer;

         /* Change this to try different formats!  If you set a colormap format

          * then you must also supply a colormap below.

          */

         image.format = PNG_FORMAT_RGBA;

         buffer = malloc(PNG_IMAGE_SIZE(image));

         if (buffer != NULL)

         {

            if (png_image_finish_read(&image, NULL/*background*/, buffer,

               0/*row_stride*/, NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP */))

            {

               if (png_image_write_to_file(&image, argv[2],

                  0/*convert_to_8bit*/, buffer, 0/*row_stride*/,

                  NULL/*colormap*/))

                  result = 0;

               else

                  fprintf(stderr, "pngtopng: write %s: %s\n", argv[2],

                      image.message);

               free(buffer);

            }

            else

            {

               fprintf(stderr, "pngtopng: read %s: %s\n", argv[1],

                   image.message);

               /* This is the only place where a 'free' is required; libpng does

                * the cleanup on error and success, but in this case we couldn't

                * complete the read because of running out of memory.

                */

               png_image_free(&image);

            }

         }

         else

            fprintf(stderr, "pngtopng: out of memory: %lu bytes\n",

               (unsigned long)PNG_IMAGE_SIZE(image));

      }

      else

         /* Failed to read the first argument: */

         fprintf(stderr, "pngtopng: %s: %s\n", argv[1], image.message);

   }

   else

      /* Wrong number of arguments */

      fprintf(stderr, "pngtopng: usage: pngtopng input-file output-file\n");

   return result;

}

#endif /* READ && WRITE */