linux lcd应用编程

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

#define FB_DEVICE "/dev/fb0"

int main() {
    int fb_fd = open(FB_DEVICE, O_RDWR);
    if (fb_fd == -1) {
        perror("Error opening framebuffer device");
        exit(1);
    }

    struct fb_var_screeninfo vinfo;
    if (ioctl(fb_fd, FBIOGET_VSCREENINFO, &vinfo) == -1) {
        perror("Error reading variable information");
        close(fb_fd);
        exit(1);
    }

    long screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
    char *fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED, fb_fd, 0);
    if ((int)fbp == -1) {
        perror("Error mapping framebuffer");
        close(fb_fd);
        exit(1);
    }

    // Clear the screen
    memset(fbp, 0, screensize);

    // Write some text
    char *message = "Hello, LCD!";
    int x = 10;
    int y = 10;
    int font_size = 16;
    for (int i = 0; message[i] != '\0'; i++) {
        // Draw each character at (x, y)
        // This is a simplified example; actual font rendering would be more complex
        for (int j = 0; j < font_size; j++) {
            for (int k = 0; k < font_size; k++) {
                if (font_bitmap[message[i]][j][k]) { // Assuming font_bitmap is defined
                    long location = (x + k + (y + j) * vinfo.xres) * (vinfo.bits_per_pixel / 8);
                    *(fbp + location) = 255;     // Some blue
                    *(fbp + location + 1) = 0;   // Some green
                    *(fbp + location + 2) = 0;   // Some red
                }
            }
        }
        x += font_size;
    }

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