fb直接渲染

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <getopt.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <malloc.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <asm/types.h>
#include <linux/videodev2.h>

#include <linux/fb.h>

static void main(struct fb_var_screeninfo *vinfo)

{
    int fbfd = 0;
    unsigned long screensize = 0;

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

    // Get variable screen information
    if (ioctl(fbfd, FBIOGET_VSCREENINFO, vinfo)) {
        printf("Error reading variable information.\n");
        exit(1);
    }

    printf("%dx%d, %dbpp\n", vinfo->xres, vinfo->yres, vinfo->bits_per_pixel);
//    if (vinfo.bits_per_pixel != 16) {
//        printf("Error: not supported bits_per_pixel, it only supports 16 bit color\n");
//        exit(1);
//    }

    // Figure out the size of the screen in bytes
    screensize = vinfo->xres * vinfo->yres * 4;
    printf("screensize %d\n", screensize);
    // Map the device to memory
    fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED,
        fbfd, 0);
    if ((int)fbp == -1) {
        printf("Error: failed to map framebuffer device to memory.\n");
        exit(4);
    }
    printf("The framebuffer device was mapped to memory successfully.\n");

}