summaryrefslogtreecommitdiff
path: root/fitz/image_jpeg.c
blob: f53b6124ff9ee93e4caaf68bfa403d5638c75345 (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
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
#include "fitz.h"

#include <jpeglib.h>
#include <setjmp.h>

struct jpeg_error_mgr_jmp
{
	struct jpeg_error_mgr super;
	jmp_buf env;
	char msg[JMSG_LENGTH_MAX];
};

static void error_exit(j_common_ptr cinfo)
{
	struct jpeg_error_mgr_jmp *err = (struct jpeg_error_mgr_jmp *)cinfo->err;
	cinfo->err->format_message(cinfo, err->msg);
	longjmp(err->env, 1);
}

static void init_source(j_decompress_ptr cinfo)
{
	/* nothing to do */
}

static void term_source(j_decompress_ptr cinfo)
{
	/* nothing to do */
}

static boolean fill_input_buffer(j_decompress_ptr cinfo)
{
	static unsigned char eoi[2] = { 0xFF, JPEG_EOI };
	struct jpeg_source_mgr *src = cinfo->src;
	src->next_input_byte = eoi;
	src->bytes_in_buffer = 2;
	return 1;
}

static void skip_input_data(j_decompress_ptr cinfo, long num_bytes)
{
	struct jpeg_source_mgr *src = cinfo->src;
	if (num_bytes > 0)
	{
		src->next_input_byte += num_bytes;
		src->bytes_in_buffer -= num_bytes;
	}
}

fz_pixmap *
fz_load_jpeg(fz_context *ctx, unsigned char *rbuf, int rlen)
{
	struct jpeg_decompress_struct cinfo;
	struct jpeg_error_mgr_jmp err;
	struct jpeg_source_mgr src;
	unsigned char *row[1], *sp, *dp;
	fz_colorspace *colorspace;
	unsigned int x;
	int k;

	fz_pixmap *image = NULL;

	if (setjmp(err.env))
	{
		if (image)
			fz_drop_pixmap(ctx, image);
		fz_throw(ctx, "jpeg error: %s", err.msg);
	}

	cinfo.err = jpeg_std_error(&err.super);
	err.super.error_exit = error_exit;

	jpeg_create_decompress(&cinfo);

	cinfo.src = &src;
	src.init_source = init_source;
	src.fill_input_buffer = fill_input_buffer;
	src.skip_input_data = skip_input_data;
	src.resync_to_restart = jpeg_resync_to_restart;
	src.term_source = term_source;
	src.next_input_byte = rbuf;
	src.bytes_in_buffer = rlen;

	jpeg_read_header(&cinfo, 1);

	jpeg_start_decompress(&cinfo);

	if (cinfo.output_components == 1)
		colorspace = fz_device_gray;
	else if (cinfo.output_components == 3)
		colorspace = fz_device_rgb;
	else if (cinfo.output_components == 4)
		colorspace = fz_device_cmyk;
	else
		fz_throw(ctx, "bad number of components in jpeg: %d", cinfo.output_components);

	fz_try(ctx)
	{
		image = fz_new_pixmap(ctx, colorspace, cinfo.output_width, cinfo.output_height);
	}
	fz_catch(ctx)
	{
		jpeg_finish_decompress(&cinfo);
		jpeg_destroy_decompress(&cinfo);
		fz_throw(ctx, "out of memory");
	}

	if (cinfo.density_unit == 1)
	{
		image->xres = cinfo.X_density;
		image->yres = cinfo.Y_density;
	}
	else if (cinfo.density_unit == 2)
	{
		image->xres = cinfo.X_density * 254 / 100;
		image->yres = cinfo.Y_density * 254 / 100;
	}

	fz_clear_pixmap(ctx, image);

	row[0] = fz_malloc(ctx, cinfo.output_components * cinfo.output_width);
	dp = image->samples;
	while (cinfo.output_scanline < cinfo.output_height)
	{
		jpeg_read_scanlines(&cinfo, row, 1);
		sp = row[0];
		for (x = 0; x < cinfo.output_width; x++)
		{
			for (k = 0; k < cinfo.output_components; k++)
				*dp++ = *sp++;
			*dp++ = 255;
		}
	}
	fz_free(ctx, row[0]);

	jpeg_finish_decompress(&cinfo);
	jpeg_destroy_decompress(&cinfo);

	return image;
}