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
|
/* +-------------------------------------------------------------------+ */
/* | Copyright 1993, David Koblas (koblas@netcom.com) | */
/* | | */
/* | Permission to use, copy, modify, and to distribute this software | */
/* | and its documentation for any purpose is hereby granted without | */
/* | fee, provided that the above copyright notice appear in all | */
/* | copies and that both that copyright notice and this permission | */
/* | notice appear in supporting documentation. There is no | */
/* | representations about the suitability of this software for | */
/* | any purpose. this software is provided "as is" without express | */
/* | or implied warranty. | */
/* | | */
/* +-------------------------------------------------------------------+ */
/* $Id: readJPEG.c,v 1.5 1996/05/07 11:22:01 torsten Exp $ */
/* Updated for IJG release 6 by Torsten Martinsen, Fri Dec 8 1995 */
#include <stdio.h>
#include <setjmp.h>
#include <stdlib.h>
#include <jpeglib.h>
#include "image.h"
#include "rwTable.h"
Image *ReadJPEG(char *file);
int TestJPEG(char *file);
static void
trace_message(j_common_ptr cinfo)
{
char buf[JMSG_LENGTH_MAX];
cinfo->err->format_message(cinfo, buf);
RWSetMsg(buf);
}
struct error_mgr {
struct jpeg_error_mgr pub; /* "public" fields */
jmp_buf setjmp_buffer; /* for return to caller */
};
static struct error_mgr jerr;
typedef struct error_mgr *error_ptr;
/*
* Here's the routine that will replace the standard error_exit method:
*/
static void
error_exit(j_common_ptr cinfo)
{
/* cinfo->err really points to a my_error_mgr struct, so coerce pointer */
error_ptr err = (error_ptr) cinfo->err;
trace_message(cinfo);
/* Return control to the setjmp point */
longjmp(err->setjmp_buffer, 1);
}
Image *
ReadJPEG(char *file)
{
struct jpeg_decompress_struct cinfo;
FILE *input_file;
int w, h, row_stride, ncolors;
JSAMPROW scanline[1];
Image *image;
if ((input_file = fopen(file, "r")) == NULL)
return NULL;
cinfo.err = jpeg_std_error(&jerr.pub);
jerr.pub.error_exit = error_exit;
if (setjmp(jerr.setjmp_buffer)) {
/* If we get here, the JPEG code has signaled an error.
* We need to clean up the JPEG object, close the input file,
* and return.
*/
jpeg_destroy_decompress(&cinfo);
fclose(input_file);
return NULL;
}
jpeg_create_decompress(&cinfo);
jpeg_stdio_src(&cinfo, input_file);
jpeg_read_header(&cinfo, TRUE);
jpeg_start_decompress(&cinfo);
h = cinfo.output_height;
w = cinfo.output_width;
if (cinfo.jpeg_color_space == JCS_GRAYSCALE) {
ncolors = cinfo.desired_number_of_colors;
image = ImageNewGrey(w, h);
row_stride = w;
} else {
image = ImageNew(w, h);
row_stride = w * 3;
}
cinfo.quantize_colors = FALSE;
while (cinfo.output_scanline < h) {
scanline[0] = (JSAMPROW) image->data + cinfo.output_scanline * row_stride;
(void) jpeg_read_scanlines(&cinfo, scanline, (JDIMENSION) 1);
}
jpeg_finish_decompress(&cinfo);
jpeg_destroy_decompress(&cinfo);
fclose(input_file);
if (jerr.pub.num_warnings > 0) { /* XXX */
RWSetMsg("JPEG warning, image may be corrupted");
longjmp(jerr.setjmp_buffer, 1);
}
return image;
}
int
TestJPEG(char *file)
{
unsigned char buf[2];
FILE *fd = fopen(file, "r");
int ret = 0;
if (fd == NULL)
return 0;
if (2 == fread(buf, sizeof(char), 2, fd)) {
if (buf[0] == 0xff && buf[1] == 0xd8)
ret = 1;
}
fclose(fd);
return ret;
}
|
