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