리눅스 프레임버퍼 예제 1

  콘솔에서 프레임버퍼에 색깔을 찍어본 예제입니다. X윈도우상에서도 결과를 보고 싶은데 안되네요.

 

1. #include <stdio.h>  
2. #include <stdlib.h>  
3. #include <string.h>  
4.     
5. #include <fcntl.h>  
6. #include <unistd.h>  
7. #include <linux/fb.h>  
8. #include <sys/mman.h>  
9.     
10.     
11. int main( int argc, char* argv[] )  
12. {  
13.     int framebuffer_fd = 0;  
14.     struct fb_var_screeninfo framebuffer_variable_screeninfo;  
15.     struct fb_fix_screeninfo framebuffer_fixed_screeninfo;  
16.     
17.     framebuffer_fd = open( "/dev/fb0", O_RDWR );  
18.     if ( framebuffer_fd <  0 ){  
19.         perror( "Error: cannot open framebuffer device\n" );  
20.         exit(1);  
21.     }  
22.     
23.     
24.     if ( ioctl(framebuffer_fd, FBIOGET_VSCREENINFO,   
25.             &framebuffer_variable_screeninfo) )  
26.     {  
27.         perror( "Error: reading variable screen infomation\n" );  
28.         exit(1);  
29.     }  
30.     framebuffer_variable_screeninfo.bits_per_pixel=32;  
31.     
32.     if ( ioctl(framebuffer_fd, FBIOPUT_VSCREENINFO,   
33.             &framebuffer_variable_screeninfo) )  
34.     {  
35.         perror( "Error: reading variable screen infomation\n" );  
36.         exit(1);  
37.     }  
38.     
39.     
40.     
41.     if ( ioctl(framebuffer_fd, FBIOGET_FSCREENINFO,   
42.             &framebuffer_fixed_screeninfo) )  
43.     {  
44.         perror( "Error: reading fixed screen infomation\n" );  
45.         exit(1);  
46.     }  
47.     
48.     printf( "framebuffer Display information\n" );  
49.     printf( " %d x %d  %d bpp\n", framebuffer_variable_screeninfo.xres,  
50.              framebuffer_variable_screeninfo.yres,   
51.              framebuffer_variable_screeninfo.bits_per_pixel );  
52.     
53.     
54.     int width  = framebuffer_variable_screeninfo.xres;  
55.     int height = framebuffer_variable_screeninfo.yres;  
56.     int bpp = framebuffer_variable_screeninfo.bits_per_pixel/8;  
57.     int xoffset = framebuffer_variable_screeninfo.xoffset;  
58.     int yoffset = framebuffer_variable_screeninfo.yoffset;  
59.     
60.     
61.     long int screensize = width*height*bpp;  
62.     
63.     
64.     char *framebuffer_pointer = (char*)mmap( 0, screensize,  
65.                                         PROT_READ|PROT_WRITE,  
66.                                         MAP_SHARED,  
67.                                         framebuffer_fd, 0 );  
68.     
69.     if ( framebuffer_pointer == MAP_FAILED )  
70.     {  
71.         perror( "Error : mmap\n" );  
72.         exit(1);  
73.     }  
74.     else  
75.         {  
76.             int x,y;  
77.             for ( y=0; y<height; y++)  
78.             for ( x=0; x<width; x++)  
79.             {  
80.                 unsigned int pixel_offset = (y+yoffset)*framebuffer_fixed_screeninfo.line_length*2 +(x+xoffset)*bpp;  
81.         
82.     
83.         if (bpp==4){  
84.             if ( x<=width*1/3){    
85.                  framebuffer_pointer[pixel_offset]=255;//B  
86.                  framebuffer_pointer[pixel_offset+1]=0;//G  
87.                  framebuffer_pointer[pixel_offset+2]=0;//R  
88.                  framebuffer_pointer[pixel_offset+3]=0;//A  
89.             }  
90.             if ( x>width*1/3 && x<=width*2/3){      
91.                  framebuffer_pointer[pixel_offset]=0;//B  
92.                  framebuffer_pointer[pixel_offset+1]=255;//G  
93.                  framebuffer_pointer[pixel_offset+2]=0;//R  
94.                  framebuffer_pointer[pixel_offset+3]=0;//A  
95.             }  
96.             if ( x>width*2/3){     
97.                  framebuffer_pointer[pixel_offset]=0;//B  
98.                  framebuffer_pointer[pixel_offset+1]=0;//G  
99.                  framebuffer_pointer[pixel_offset+2]=255;//R  
100.                  framebuffer_pointer[pixel_offset+3]=0;//A  
101.             }  
102.         }  
103.     
104.          }  
105.     
106.     }   
107.     
108.     munmap( framebuffer_pointer, screensize );   
109.     close( framebuffer_fd );  
110. }  
111.     
112.     
113.     
114.