通过 Linux FrameBuffer 将像素绘制到屏幕上

我最近被一个奇怪的 idea 打动了:从/dev/uradom获取输入，将相关字符转换为随机整数，并将这些整数用作要在屏幕上绘制的像素的rgb/x-y值.

我做了一些研究(这里是关于StackOverflow和其他地方的)，许多人建议您可以直接写入/dev/fb0，因为它是设备的文件表示形式.不幸的是，这似乎没有产生任何明显的视觉效果.

我发现一个示例C程序来自一个QT教程(不再提供)，它使用mmap写入缓冲区.程序运行成功，但同样没有输出到屏幕.有趣的是，当我将笔记本电脑置于暂停状态并随后恢复时，我看到了一个瞬间的图像(红色方块)，该图像在很久以前就写入了帧缓冲区.在Linux中，写入帧缓冲区是否可以用于绘制屏幕？理想情况下，我想写一个(ba)sh脚本，但C或类似的也可以.谢谢

编辑:这里是示 routine 序...在兽医看来可能很熟悉.

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

int main()
{
    int fbfd = 0;
    struct fb_var_screeninfo vinfo;
    struct fb_fix_screeninfo finfo;
    long int screensize = 0;
    char *fbp = 0;
    int x = 0, y = 0;
    long int location = 0;

    // Open the file for reading and writing
    fbfd = open("/dev/fb0", O_RDWR);
    if (fbfd == -1) {
        perror("Error: cannot open framebuffer device");
        exit(1);
    }
    printf("The framebuffer device was opened successfully.\n");

    // Get fixed screen information
    if (ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo) == -1) {
        perror("Error reading fixed information");
        exit(2);
    }

    // Get variable screen information
    if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo) == -1) {
        perror("Error reading variable information");
        exit(3);
    }

    printf("%dx%d, %dbpp\n", vinfo.xres, vinfo.yres, vinfo.bits_per_pixel);

    // Figure out the size of the screen in bytes
    screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;

    // Map the device to memory
    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);
    }
    printf("The framebuffer device was mapped to memory successfully.\n");

    x = 100; y = 100;       // Where we are going to put the pixel

    // Figure out where in memory to put the pixel
    for (y = 100; y < 300; y++)
        for (x = 100; x < 300; x++) {

            location = (x+vinfo.xoffset) * (vinfo.bits_per_pixel/8) +
                       (y+vinfo.yoffset) * finfo.line_length;

            if (vinfo.bits_per_pixel == 32) {
                *(fbp + location) = 100;        // Some blue
                *(fbp + location + 1) = 15+(x-100)/2;     // A little green
                *(fbp + location + 2) = 200-(y-100)/5;    // A lot of red
                *(fbp + location + 3) = 0;      // No transparency
        //location += 4;
            } else  { //assume 16bpp
                int b = 10;
                int g = (x-100)/6;     // A little green
                int r = 31-(y-100)/16;    // A lot of red
                unsigned short int t = r<<11 | g << 5 | b;
                *((unsigned short int*)(fbp + location)) = t;
            }

        }
    munmap(fbp, screensize);
    close(fbfd);
    return 0;
}