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
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
|
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <setjmp.h>
#include <string.h>
#include "jpeglib.h"
#include "meh.h"
struct error_mgr{
struct jpeg_error_mgr pub;
jmp_buf jmp_buffer;
};
struct jpeg_t{
struct image img;
FILE *f;
struct jpeg_decompress_struct cinfo;
struct error_mgr jerr;
};
static void error_exit(j_common_ptr cinfo){
(void) cinfo;
printf("\nerror!\n");
exit(1);
}
static void error_longjmp(j_common_ptr cinfo){
struct error_mgr *myerr = (struct error_mgr *)cinfo->err;
(*cinfo->err->output_message)(cinfo);
longjmp(myerr->jmp_buffer, 1);
}
/* TODO progressive */
static struct image *jpeg_open(FILE *f){
struct jpeg_t *j;
rewind(f);
if(getc(f) != 0xff || getc(f) != 0xd8)
return NULL;
j = malloc(sizeof(struct jpeg_t));
j->f = f;
j->cinfo.err = jpeg_std_error(&j->jerr.pub);
j->jerr.pub.error_exit = error_longjmp;
if (setjmp(j->jerr.jmp_buffer)) {
return NULL;
}
j->jerr.pub.error_exit = error_exit;
j->img.fmt = &libjpeg;
return (struct image *)j;
}
void jpeg_prep(struct image *img){
struct jpeg_t *j = (struct jpeg_t *)img;
jpeg_create_decompress(&j->cinfo);
rewind(j->f);
jpeg_stdio_src(&j->cinfo, j->f);
jpeg_read_header(&j->cinfo, TRUE);
/* parameters */
j->cinfo.do_fancy_upsampling = 0;
j->cinfo.do_block_smoothing = 0;
j->cinfo.quantize_colors = 0;
j->cinfo.dct_method = JDCT_FASTEST;
j->cinfo.scale_denom = (img->state & LOADED) ? 1 : 8; /* TODO: This should be changed done only for large jpegs */
jpeg_calc_output_dimensions(&j->cinfo);
j->img.bufwidth = j->cinfo.output_width;
j->img.bufheight = j->cinfo.output_height;
}
static int jpeg_read(struct image *img){
struct jpeg_t *j = (struct jpeg_t *)img;
unsigned int row_stride;
int a = 0, b;
unsigned int x, y;
j->jerr.pub.error_exit = error_longjmp;
if(setjmp(j->jerr.jmp_buffer)){
return 1; /* ERROR */
}
row_stride = j->cinfo.output_width * j->cinfo.output_components;
jpeg_start_decompress(&j->cinfo);
if(j->cinfo.output_components == 3){
JSAMPROW rows[2];
rows[0] = img->buf;
rows[1] = rows[0] + row_stride;
for(y = 0; y < j->cinfo.output_height;){
int n = jpeg_read_scanlines(&j->cinfo, rows, 2);
y += n;
rows[0] = rows[n-1] + row_stride;
rows[1] = rows[0] + row_stride;
}
}else if(j->cinfo.output_components == 1){
JSAMPARRAY buffer = (*j->cinfo.mem->alloc_sarray)((j_common_ptr)&j->cinfo, JPOOL_IMAGE, row_stride, 4);
for(y = 0; y < j->cinfo.output_height; ){
int n = jpeg_read_scanlines(&j->cinfo, buffer, 4);
for(b = 0; b < n; b++){
for(x = 0; x < j->cinfo.output_width; x++){
img->buf[a++] = buffer[b][x];
img->buf[a++] = buffer[b][x];
img->buf[a++] = buffer[b][x];
}
}
y += n;
}
}else if(j->cinfo.output_components == 4){
JSAMPARRAY buffer = (*j->cinfo.mem->alloc_sarray)((j_common_ptr)&j->cinfo, JPOOL_IMAGE, row_stride, 4);
for(y = 0; y < j->cinfo.output_height; ){
int n = jpeg_read_scanlines(&j->cinfo, buffer, 4);
for(b = 0; b < n; b++){
for(x = 0; x < j->cinfo.output_width; x++){
int tmp = buffer[b][x*4 + 3];
img->buf[a++] = buffer[b][x*4] * tmp / 255;
img->buf[a++] = buffer[b][x*4 + 1] * tmp / 255;
img->buf[a++] = buffer[b][x*4 + 2] * tmp / 255;
}
}
y += n;
}
}else{
fprintf(stderr, "Unsupported number of output components: %u\n", j->cinfo.output_components);
return 1;
}
jpeg_finish_decompress(&j->cinfo);
img->state |= LOADED;
if(j->cinfo.scale_denom == 1)
img->state |= SLOWLOADED;
return 0;
}
void jpeg_close(struct image *img){
struct jpeg_t *j = (struct jpeg_t *)img;
jpeg_destroy_decompress(&j->cinfo);
fclose(j->f);
}
struct imageformat libjpeg = {
jpeg_open,
jpeg_prep,
jpeg_read,
jpeg_close
};
|
