ls -l /dev/fb0 (Enter)
crw-rw---- 1 root video 29, 0 Jan 27 15:32 /dev/fb0
cat /dev/fb0 > sreensnap
ls -l sreensnap
-rw-r--r-- 1 wsw wsw 6291456 Jan 27 21:30 sreensnap
clear /*清楚屏幕的输出*/
cat sreensnap > /dev/fb0
clear
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <linux/fb.h>
#include <sys/mman.h>
int main () {
int fp=0;
struct fb_var_screeninfo vinfo;
struct fb_fix_screeninfo finfo;
fp = open ("/dev/fb0",O_RDWR);
if (fp < 0){
printf("Error : Can not open framebuffer device\n");
exit(1);
}
if (ioctl(fp,FBIOGET_FSCREENINFO,&finfo)){
printf("Error reading fixed information\n");
exit(2);
}
if (ioctl(fp,FBIOGET_VSCREENINFO,&vinfo)){
printf("Error reading variable information\n");
exit(3);
}
printf("The mem is :%d\n",finfo.smem_len);
printf("The line_length is :%d\n",finfo.line_length);
printf("The xres is :%d\n",vinfo.xres);
printf("The yres is :%d\n",vinfo.yres);
printf("bits_per_pixel is :%d\n",vinfo.bits_per_pixel);
close (fp);
}
The mem is :6291456
The line_length is :4096
The xres is :1024
The yres is :768
bits_per_pixel is :32
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <linux/fb.h>
#include <sys/mman.h>
int main () {
int fp=0;
struct fb_var_screeninfo vinfo;
struct fb_fix_screeninfo finfo;
long screensize=0;
char *fbp = 0;
int x = 0, y = 0;
long location = 0;
fp = open ("/dev/fb0",O_RDWR);
if (fp < 0){
printf("Error : Can not open framebuffer device\n");
exit(1);
}
if (ioctl(fp,FBIOGET_FSCREENINFO,&finfo)){
printf("Error reading fixed information\n");
exit(2);
}
if (ioctl(fp,FBIOGET_VSCREENINFO,&vinfo)){
printf("Error reading variable information\n");
exit(3);
}
screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
/*这就是把fp所指的文件中从开始到screensize大小的内容给映射出来,得到一个指向这块空间的指针*/
fbp =(char *) mmap (0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED, fp,0);
if ((int) fbp == -1)
{
printf ("Error: failed to map framebuffer device to memory.\n");
exit (4);
}
/*这是你想画的点的位置坐标,(0,0)点在屏幕左上角*/
x = 100;
y = 100;
location = x * (vinfo.bits_per_pixel / 8) + y * finfo.line_length;
*(fbp + location) = 100; /* 蓝色的色深 */ /*直接赋值来改变屏幕上某点的颜色*/
*(fbp + location + 1) = 15; /* 绿色的色深*/
*(fbp + location + 2) = 200; /* 红色的色深*/
*(fbp + location + 3) = 0; /* 是否透明*/
munmap (fbp, screensize); /*解除映射*/
close (fp); /*关闭文件*/
return 0;
}
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