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[AROS.git] / workbench / libs / png / contrib / examples / pngtopng.c
blobb1b3be677b90870ce430aa58511dbb4086d81f0d
1 /*- pngtopng
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.
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.
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.
14 #include <stddef.h>
15 #include <stdlib.h>
16 #include <string.h>
17 #include <stdio.h>
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:
22 #include "../../png.h"
24 int main(int argc, const char **argv)
26 int result = 1;
28 if (argc == 3)
30 png_image image;
32 /* Only the image structure version number needs to be set. */
33 memset(&image, 0, sizeof image);
34 image.version = PNG_IMAGE_VERSION;
36 if (png_image_begin_read_from_file(&image, argv[1]))
38 png_bytep buffer;
40 /* Change this to try different formats! If you set a colormap format
41 * then you must also supply a colormap below.
43 image.format = PNG_FORMAT_RGBA;
45 buffer = malloc(PNG_IMAGE_SIZE(image));
47 if (buffer != NULL)
49 if (png_image_finish_read(&image, NULL/*background*/, buffer,
50 0/*row_stride*/, NULL/*colormap for PNG_FORMAT_FLAG_COLORMAP */))
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;
57 else
58 fprintf(stderr, "pngtopng: write %s: %s\n", argv[2],
59 image.message);
61 free(buffer);
64 else
66 fprintf(stderr, "pngtopng: read %s: %s\n", argv[1],
67 image.message);
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.
73 png_image_free(&image);
77 else
78 fprintf(stderr, "pngtopng: out of memory: %lu bytes\n",
79 (unsigned long)PNG_IMAGE_SIZE(image));
82 else
83 /* Failed to read the first argument: */
84 fprintf(stderr, "pngtopng: %s: %s\n", argv[1], image.message);
87 else
88 /* Wrong number of arguments */
89 fprintf(stderr, "pngtopng: usage: pngtopng input-file output-file\n");
91 return result;