hifb.c示例代码

// hifb.c示例代码
#include 
#include 
#include 

#define FRAMEBUFFER_SIZE (1920*1080*4)

int main(int argc, char *argv[])
{
    int fbfd = 0;
    char *fbp = 0;
    int x = 0, y = 0;
    long int screensize = 0;

    // 打开设备文件
    fbfd = open("/dev/fb0", O_RDWR);
    if (fbfd == -1) {
        perror("Error: cannot open framebuffer device");
        exit(1);
    }

    // 获取设备信息
    struct fb_var_screeninfo vinfo;
    struct fb_fix_screeninfo finfo;
    if (ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo) == -1) {
        perror("Error reading fixed information");
        exit(2);
    }
    if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo) == -1) {
        perror("Error reading variable information");
        exit(3);
    }

    // 计算屏幕的大小
    screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;

    // 映射到内存中
    fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED, fbfd, 0);
    if ((int)fbp == -1) {
        perror("Error: failed to map framebuffer device to memory");
        exit(4);
    }

    // 将屏幕清空为黑色
    memset(fbp, 0, screensize);

    // 在屏幕上绘制一个红色的矩形
    for (y = 100; y < 300; y++) {
        for (x = 100; x < 300; x++) {
            long int location = (x + vinfo.xoffset) * (vinfo.bits_per_pixel / 8) +
                                (y + vinfo.yoffset) * finfo.line_length;
            *(fbp + location) = 0; // 蓝色
            *(fbp + location + 1) = 0; // 绿色
            *(fbp + location + 2) = 255; // 红色
            *(fbp + location + 3) = 0; // 透明度
        }
    }

    // 等待用户按下任意键后退出
    printf("Press any key to exit...\n");
    getchar();

    // 取消映射并关闭设备文件
    munmap(fbp, screensize);
    close(fbfd);

    return 0;
}