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
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
|
/**
* xrdp: A Remote Desktop Protocol server.
*
* Copyright (C) Laxmikant Rashinkar 2004-2012
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdint.h>
#include "common.h"
// multi byte values are stored in little endian
struct bmp_magic
{
char magic[2];
};
struct bmp_hdr
{
uint32_t size; // file size in bytes
uint16_t reserved1;
uint16_t reserved2;
uint32_t offset; // offset to image data, in bytes
};
struct dib_hdr
{
uint32_t hdr_size;
int32_t width;
int32_t height;
uint16_t nplanes;
uint16_t bpp;
uint32_t compress_type;
uint32_t image_size;
int32_t hres;
int32_t vres;
uint32_t ncolors;
uint32_t nimpcolors;
};
// forward declarations
int parse_bmp(char *filename, struct pic_info *pic_info);
int parse_bmp_24(struct bmp_hdr *bmp_hdr, struct dib_hdr *dib_hdr, int fd, struct pic_info *pic_info);
int parse_bmp(char *filename, struct pic_info *pic_info)
{
int got_magic;
int fd;
int rval;
struct bmp_magic magic;
struct bmp_hdr bmp_hdr;
struct dib_hdr dib_hdr;
if ((fd = open(filename, O_RDONLY)) < 0)
{
printf("error opeing %s\n", filename);
return -1;
}
// read BMP magic...
if ((rval = read(fd, magic.magic, 2)) != 2)
{
fprintf(stderr, "error reading BMP signature from file %s\n", filename);
return -1;
}
got_magic = 0;
// ...and confirm that this is indeed a BMP file
if ((magic.magic[0] == 'B') && (magic.magic[1] == 'M'))
{
// BM – Windows 3.1x, 95, NT, ... etc
got_magic = 1;
}
else if ((magic.magic[0] == 'B') && (magic.magic[1] == 'A'))
{
// BA – OS/2 struct Bitmap Array
got_magic = 1;
}
else if ((magic.magic[0] == 'C') && (magic.magic[1] == 'I'))
{
// CI – OS/2 struct Color Icon
got_magic = 1;
}
else if ((magic.magic[0] == 'C') && (magic.magic[1] == 'P'))
{
// CP – OS/2 const Color Pointer
got_magic = 1;
}
else if ((magic.magic[0] == 'I') && (magic.magic[1] == 'C'))
{
// IC – OS/2 struct Icon
got_magic = 1;
}
else if ((magic.magic[0] == 'P') && (magic.magic[1] == 'T'))
{
// PT – OS/2 Pointer
got_magic = 1;
}
if (!got_magic)
{
fprintf(stderr, "%s is not a valid BMP file\n", filename);
return -1;
}
// read BMP header
if ((rval = read(fd, &bmp_hdr, sizeof(bmp_hdr))) < sizeof(bmp_hdr))
{
fprintf(stderr, "error BMP header from file %s\n", filename);
return -1;
}
// read DIB header
if ((rval = read(fd, &dib_hdr, sizeof(dib_hdr))) < sizeof(dib_hdr))
{
fprintf(stderr, "error reading DIB header from file %s\n", filename);
return -1;
}
#if 0
printf("header size: %d\n", dib_hdr.hdr_size);
printf("width: %d\n", dib_hdr.width);
printf("height: %d\n", dib_hdr.height);
printf("num planes: %d\n", dib_hdr.nplanes);
printf("bpp: %d\n", dib_hdr.bpp);
printf("comp type: %d\n", dib_hdr.compress_type);
printf("image size: %d\n", dib_hdr.image_size);
printf("hres: %d\n", dib_hdr.hres);
printf("vres: %d\n", dib_hdr.vres);
printf("ncolors: %d\n", dib_hdr.ncolors);
printf("nimpcolors: %d\n", dib_hdr.nimpcolors);
#endif
if (dib_hdr.compress_type)
{
printf("TODO: compressed images not yet supported\n");
return -1;
}
pic_info->width = dib_hdr.width;
pic_info->height = dib_hdr.height;
if (dib_hdr.bpp == 24)
{
rval = parse_bmp_24(&bmp_hdr, &dib_hdr, fd, pic_info);
}
close(fd);
return rval;
}
/**
* extract 24bit BMP data from image file
*
* @return 0 on success
* @return -1 on failure
*/
int parse_bmp_24(
struct bmp_hdr *bmp_hdr,
struct dib_hdr *dib_hdr,
int fd,
struct pic_info *pic_info
)
{
char *file_data;
char *ptr_file_data;
char *mem_data;
char *ptr_mem_data;
char *cptr;
int w = dib_hdr->width; // picture width
int h = dib_hdr->height; // picture height
int bpl; // bytes per line
int bytes;
int i;
int j;
// bytes per image line = width x bytes_per_pixel + padding
i = (w * 3) % 4;
j = (i == 0) ? 0 : 4 - i;
bpl = w * 3 + j;
// 24 bit depth, no alpha channel
file_data = (char *) malloc(h * bpl);
// point to first line in image data, which is stored in reverse order
ptr_file_data = (file_data + dib_hdr->image_size) - bpl;
// 24 bit depth, with alpha channel
mem_data = (char *) malloc(w * h * 4);
ptr_mem_data = mem_data;
pic_info->pixel_data = ptr_mem_data;
// seek to beginning of pixel data
lseek(fd, bmp_hdr->offset, SEEK_SET);
// read all pixel data
bytes = read(fd, file_data, dib_hdr->image_size);
// convert 24bit to 24 bit with alpha and store in reverse
for (i = 0; i < h; i ++)
{
cptr = ptr_file_data;
for (j = 0; j < w; j++)
{
*ptr_mem_data++ = *cptr++; // blue value
*ptr_mem_data++ = *cptr++; // green value
*ptr_mem_data++ = *cptr++; // red value
*ptr_mem_data++ = 0; // alpha channel
}
ptr_file_data -= bpl;
}
free(file_data);
return 0;
}
|
