blob: bf90f2d79c357596799166d33caaf2a027531c17 (
plain)
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
|
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <setjmp.h>
#include <string.h>
#include "jpeglib.h"
#include "jpeg.h"
struct error_mgr{
struct jpeg_error_mgr pub;
jmp_buf jmp_buffer;
};
static void error_exit(j_common_ptr cinfo){
printf("\nerror!\n");
exit(1);
}
unsigned char *loadjpeg(FILE *infile, int *width, int *height){
struct jpeg_decompress_struct cinfo;
struct error_mgr jerr;
JSAMPARRAY buffer;
int row_stride;
int i = 0;
int j;
int y;
unsigned char *retbuf;
cinfo.err = jpeg_std_error(&jerr.pub);
jerr.pub.error_exit = error_exit;
jpeg_create_decompress(&cinfo);
jpeg_stdio_src(&cinfo, infile);
jpeg_read_header(&cinfo, TRUE);
/* parameters */
cinfo.do_fancy_upsampling = 0;
cinfo.do_block_smoothing = 0;
cinfo.quantize_colors = 0;
cinfo.dct_method = JDCT_IFAST;
jpeg_calc_output_dimensions(&cinfo);
row_stride = cinfo.output_width * cinfo.output_components;
buffer = (*cinfo.mem->alloc_sarray)((j_common_ptr)&cinfo, JPOOL_IMAGE, row_stride, 4);
jpeg_start_decompress(&cinfo);
*width = cinfo.output_width;
*height = cinfo.output_height;
retbuf = malloc(4 * cinfo.output_components * (cinfo.output_width * cinfo.output_height));
if(cinfo.output_components != 3){
fprintf(stderr, "TODO: greyscale images are not supported\n");
exit(1);
}
for(y = 0; y < cinfo.output_height; ){
int n = jpeg_read_scanlines(&cinfo, buffer, 4);
for(j = 0; j < n; j++){
memcpy(&retbuf[i], buffer[j], row_stride);
i += row_stride;
}
y += n;
}
jpeg_finish_decompress(&cinfo);
jpeg_destroy_decompress(&cinfo);
return retbuf;
}
|
