1. 给/dev/fb0权限

sudo chmod 0777 /dev/fb0
注意：不执行这一条权限，无法获取任何数据

2. 获取屏幕尺寸

int fd;
struct fb_var_screeninfo screenInfo;
fd = open("/dev/fb0",O_RDWR);
ioctl(fd,FBIOGET_VSCREENINFO,&screenInfo);
printf("%d*%d\n",screenInfo.width,screenInfo.yres_virtual);
close(fd);

3. 需要的头文件

#include<stdio.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<sys/mman.h>
#include<sys/ioctl.h>
#include<unistd.h>
#include<fcntl.h>
#include<linux/fb.h>