1/*- pngtopng
 2 *
 3 * COPYRIGHT: Written by John Cunningham Bowler, 2011, 2017.
 4 * To the extent possible under law, the author has waived all copyright and
 5 * related or neighboring rights to this work.  This work is published from:
 6 * United States.
 7 *
 8 * Last changed in libpng 1.6.29 [March 16, 2017]
 9 *
10 * Read a PNG and write it out in a fixed format, using the 'simplified API'
11 * that was introduced in libpng-1.6.0.
12 *
13 * This sample code is just the code from the top of 'example.c' with some error
14 * handling added.  See example.c for more comments.
15 */
16#include <stddef.h>
17#include <stdlib.h>
18#include <string.h>
19#include <stdio.h>
20
21/* Normally use <png.h> here to get the installed libpng, but this is done to
22 * ensure the code picks up the local libpng implementation:
23 */
24#include "../../png.h"
25#if defined(PNG_SIMPLIFIED_READ_SUPPORTED) && \
26    defined(PNG_SIMPLIFIED_WRITE_SUPPORTED)
27
28int main(int argc, const char **argv)
29{
30   int result = 1;
31
32   if (argc == 3)
33   {
34      png_image image;
35
36      /* Only the image structure version number needs to be set. */
37      memset(&image, 0, sizeof image);
38      image.version = PNG_IMAGE_VERSION;
39
40      if (png_image_begin_read_from_file(&image, argv[1]))
41      {
42         png_bytep buffer;
43
44         /* Change this to try different formats!  If you set a colormap format
45          * then you must also supply a colormap below.
46          */
47         image.format = PNG_FORMAT_RGBA;
48
49         buffer = malloc(PNG_IMAGE_SIZE(image));
50
51         if (buffer != NULL)
52         {
53            if (png_image_finish_read(&image, NULL/*background*/, buffer,
54               0/*row_stride*/, NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP */))
55            {
56               if (png_image_write_to_file(&image, argv[2],
57                  0/*convert_to_8bit*/, buffer, 0/*row_stride*/,
58                  NULL/*colormap*/))
59                  result = 0;
60
61               else
62                  fprintf(stderr, "pngtopng: write %s: %s\n", argv[2],
63                      image.message);
64            }
65
66            else
67               fprintf(stderr, "pngtopng: read %s: %s\n", argv[1],
68                   image.message);
69
70            free(buffer);
71         }
72
73         else
74         {
75            fprintf(stderr, "pngtopng: out of memory: %lu bytes\n",
76               (unsigned long)PNG_IMAGE_SIZE(image));
77
78            /* This is the only place where a 'free' is required; libpng does
79             * the cleanup on error and success, but in this case we couldn't
80             * complete the read because of running out of memory and so libpng
81             * has not got to the point where it can do cleanup.
82             */
83            png_image_free(&image);
84         }
85      }
86
87      else
88         /* Failed to read the first argument: */
89         fprintf(stderr, "pngtopng: %s: %s\n", argv[1], image.message);
90   }
91
92   else
93      /* Wrong number of arguments */
94      fprintf(stderr, "pngtopng: usage: pngtopng input-file output-file\n");
95
96   return result;
97}
98#endif /* READ && WRITE */