1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
|
/*- pngtopng
*
* COPYRIGHT: Written by John Cunningham Bowler, 2011, 2017.
* 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.
*
* Last changed in libpng 1.6.29 [March 16, 2017]
*
* 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>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
/* Normally use <png.h> here to get the installed libpng, but this is done to
* 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);
}
else
fprintf(stderr, "pngtopng: read %s: %s\n", argv[1],
image.message);
free(buffer);
}
else
{
fprintf(stderr, "pngtopng: out of memory: %lu bytes\n",
(unsigned long)PNG_IMAGE_SIZE(image));
/* 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 and so libpng
* has not got to the point where it can do cleanup.
*/
png_image_free(&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 */
|
