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
|
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <string.h>
typedef enum {
kRetSucc,
kRetFail,
} Ret;
typedef struct {
int width;
int height;
float *buffer;
} Picture;
Picture new_picture(int width, int height) {
Picture ret;
ret.width = width;
ret.height = height;
ret.buffer = malloc(sizeof(float) * width * height * 3);
return ret;
}
void delete_picture(Picture pic) {
free(pic.buffer);
}
void set_pixel(Picture pic, int x, int y, float r, float g, float b) {
int idx = y * pic.width * 3 + x * 3;
pic.buffer[idx] = b;
pic.buffer[idx+1] = g;
pic.buffer[idx+2] = r;
}
Ret fwrite_word16le(FILE* fp, uint16_t x) {
uint8_t buf[2];
buf[0] = x & 0xff;
buf[1] = (x >> 8) & 0xff;
int r = fwrite(buf, 1, 2, fp);
if (r != 2) return kRetFail;
return kRetSucc;
}
Ret fwrite_word32le(FILE* fp, uint32_t x) {
Ret ret;
uint16_t buf[2];
buf[0] = x & 0xffff;
buf[1] = (x >> 16) & 0xffff;
ret = fwrite_word16le(fp, buf[0]);
if (ret != kRetSucc) return ret;
ret = fwrite_word16le(fp, buf[1]);
if (ret != kRetSucc) return ret;
return kRetSucc;
}
Ret writeBMP(const char* filename, Picture pic) {
Ret ret = kRetFail;
FILE *fp = NULL;
uint8_t *databuf = NULL;
fp = fopen(filename, "wb");
if (!fp) goto end;
int row_data_len = 3 * pic.width;
int padding = (4 - row_data_len % 4) % 4;
int row_len = row_data_len + padding;
int img_len = row_len * pic.height;
int file_len = 53 + img_len;
ret = fwrite_word16le(fp, 0x4d42);
if (ret != kRetSucc) goto end;
ret = fwrite_word32le(fp, file_len);
if (ret != kRetSucc) goto end;
ret = fwrite_word32le(fp, 0);
if (ret != kRetSucc) goto end;
ret = fwrite_word32le(fp, 54);
if (ret != kRetSucc) goto end;
ret = fwrite_word32le(fp, 40);
if (ret != kRetSucc) goto end;
ret = fwrite_word32le(fp, pic.width);
if (ret != kRetSucc) goto end;
ret = fwrite_word32le(fp, -pic.height);
if (ret != kRetSucc) goto end;
ret = fwrite_word16le(fp, 1);
if (ret != kRetSucc) goto end;
ret = fwrite_word16le(fp, 24);
if (ret != kRetSucc) goto end;
ret = fwrite_word32le(fp, 0); // BI_RGB
if (ret != kRetSucc) goto end;
ret = fwrite_word32le(fp, img_len);
if (ret != kRetSucc) goto end;
ret = fwrite_word32le(fp, 0);
if (ret != kRetSucc) goto end;
ret = fwrite_word32le(fp, 0);
if (ret != kRetSucc) goto end;
ret = fwrite_word32le(fp, 0);
if (ret != kRetSucc) goto end;
ret = fwrite_word32le(fp, 0);
if (ret != kRetSucc) goto end;
databuf = malloc(img_len);
memset(databuf, 0, img_len);
for (int i = 0; i < pic.height; i++) {
for (int j = 0; j < pic.width * 3; j++) {
int fromidx = i * pic.width * 3 + j;
int toidx = i * row_len + j;
float value = pic.buffer[fromidx];
if (value < 0) databuf[toidx] = 0;
else if (value > 1.0) {
databuf[toidx] = 255;
} else databuf[toidx] = 255 * value;
}
}
if (fwrite(databuf, 1, img_len, fp) != img_len) {
ret = kRetFail;
goto end;
}
ret = kRetSucc;
end:
if (databuf != NULL) free(databuf);
if (fp != NULL) fclose(fp);
return ret;
}
int main() {
Picture pic = new_picture(1600, 900);
for (int i = 0; i < 900; i++) {
for (int j = 0; j < 1600; j++) {
float r = (i + j) % 177 / 177.0;
float g = (i + j) % 71 / 71.0;
float b = (i + j) % 337 / 337.0;
set_pixel(pic, j, i, r, g, b);
}
}
writeBMP("test.bmp", pic);
delete_picture(pic);
return 0;
}
|
