24位位图bmp转换为字符

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <stdint.h>
 4 #include <windows.h>
 5 int32_t width,height;
 6 RGBQUAD *pixels;
 7 bool OpenBitmap(char const *filename)
 8 {
 9     FILE *file = fopen(filename, "rb");
10     if (file)
11     {
12         width=0;
13         height=0;
14         BITMAPFILEHEADER bf;
15         BITMAPINFOHEADER bi;
16         fread(&bf, sizeof(bf), 1, file);
17         fread(&bi, sizeof(bi), 1, file);
18         if(bi.biBitCount!=24)
19             return false;
20         if(bi.biCompression!=BI_RGB)
21             return false;
22         width=bi.biWidth;
23         height=bi.biHeight;
24         pixels=new RGBQUAD[width*height];
25         uint32_t rowSize = (bi.biBitCount * width + 31) / 32 * 4;
26         uint8_t *line = new uint8_t[rowSize];
27         for (int y = 0; y < height; y++)
28         {
29             fread(line, rowSize, 1, file);
30             for (int x = 0; x < width; x++)
31             {
32                 uint8_t *color = line + x * 3;
33                 RGBQUAD *pixel = &pixels[(height-y-1) * width+x];
34                 pixel->rgbBlue  = color[0];
35                 pixel->rgbGreen = color[1];
36                 pixel->rgbRed   = color[2];
37             }
38         }
39         delete[] line;
40         fclose(file);
41         return true;
42     }
43     return false;
44 }
45 RGBQUAD GetColor(int x, int y, int w, int h)
46 {
47     int r = 0, g = 0, b = 0;
48     for (int i = 0; i < w; i++)
49     {
50         if (i + x >= width) continue;
51         for (int j = 0; j < h; j++)
52         {
53             if (j + y >= height) continue;
54             RGBQUAD const& color = pixels[(y + j) * width + (x + i)];
55             r += color.rgbRed;
56             g += color.rgbGreen;
57             b += color.rgbBlue;
58         }
59     }
60     return RGBQUAD{r / (w * h), g / (w * h),b / (w * h)};
61 }
62 char ColorToCharacter(RGBQUAD const& color)
63 {
64     int brightness = (color.rgbRed + color.rgbGreen + color.rgbBlue) / 3;
65     static char const *characters = "Qo0V1;:*-. ";
66     int count = strlen(characters);
67     int span = 0xFF / count;
68     int cidx = brightness / span;
69     if (cidx == count)
70         cidx--;
71     return characters[cidx];
72 }
73 void OutputAscii(const char* filename, int w, int h)
74 {
75     FILE *file=fopen(filename,"w");
76     int x = width  / w;
77     int y = height / h;
78     for (int i = 0; i < height; i += y)
79     {
80         for (int j = 0; j < width; j += x)
81         {
82             RGBQUAD color = GetColor(j, i, x, y);
83             fprintf(file, "%c", ColorToCharacter(color));
84             //printf("%c", ColorToCharacter(color));
85         }
86         fprintf(file, "\n");
87         //printf("\n");
88     }
89 }
90 int main()
91 {
92     if(OpenBitmap("a.bmp"))
93         OutputAscii("a.txt",width/6,height/12);
94     return 0;
95 }