linux drm 写屏幕

#include <fcntl.h>
#include <linux/fb.h>
#include <linux/drm.h>
#include <sys/mman.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

int main() {
    int fd = open("/dev/dri/card0", O_RDWR);
    if (fd < 0) {
        perror("open");
        return -1;
    }

    struct drm_mode_get_fb fb;
    if (drmIoctl(fd, DRM_IOCTL_MODE_GET_FB, &fb) < 0) {
        perror("drmIoctl");
        close(fd);
        return -1;
    }

    void *fb_ptr = mmap(0, fb.fb_bo->offset, PROT_READ | PROT_WRITE, MAP_SHARED, fd, fb.fb_bo->offset);
    if (fb_ptr == MAP_FAILED) {
        perror("mmap");
        close(fd);
        return -1;
    }

    // 假设我们有一个简单的图像数据
    unsigned char image[fb.fb_width * fb.fb_height * 4];
    for (int i = 0; i < fb.fb_width * fb.fb_height * 4; i++) {
        image[i] = 0xFF; // 白色图像
    }

    memcpy(fb_ptr, image, fb.fb_width * fb.fb_height * 4);

    munmap(fb_ptr, fb.fb_bo->offset);
    close(fd);

    return 0;
}