linux中frambuffer写一个显示BMP格式图片的程序

您可以使用以下步骤在Linux中编写一个显示BMP格式图片的程序：

1. 包含所需的头文件和库：

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

2. 打开并映射帧缓冲设备：

int fbfd = open("/dev/fb0", O_RDWR);
struct fb_var_screeninfo vinfo;
ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo);
int screensize = vinfo.xres * vinfo.yres * vinfo.bits_per_pixel / 8;
char *fbp = (char *)mmap(0, screensize, PROT_READ | PROT_WRITE, MAP_SHARED, fbfd, 0);

3. 打开并读取BMP文件头：

FILE *bmpfile = fopen("image.bmp", "rb");
unsigned char bmpheader[54];
fread(bmpheader, sizeof(unsigned char), 54, bmpfile);

4. 读取BMP图像数据并将其复制到帧缓冲中：

unsigned char *bmpdata = (unsigned char *)malloc(screensize);
fread(bmpdata, sizeof(unsigned char), screensize, bmpfile);

for (int y = 0; y < vinfo.yres; y++) {
    for (int x = 0; x < vinfo.xres; x++) {
        long location = (x + vinfo.xoffset) * (vinfo.bits_per_pixel / 8) +
                         (y + vinfo.yoffset) * vinfo.bytes_per_line;
        unsigned char b = bmpdata[(x + (vinfo.xres * (vinfo.yres - y - 1))) * 3];
        unsigned char g = bmpdata[(x + (vinfo.xres * (vinfo.yres - y - 1))) * 3 + 1];
        unsigned char r = bmpdata[(x + (vinfo.xres * (vinfo.yres - y - 1))) * 3 + 2];
        unsigned int color = ((r << vinfo.red.offset) & vinfo.red.msb) |
                             ((g << vinfo.green.offset) & vinfo.green.msb) |
                             ((b << vinfo.blue.offset) & vinfo.blue.msb);
        *((unsigned int *)(fbp + location)) = color;
    }
}

fclose(bmpfile);
free(bmpdata);

5. 关闭帧缓冲设备和解除映射：

munmap(fbp, screensize);
close(fbfd);

这样就完成了在Linux中显示BMP格式图片的程序。请注意，您需要将图片命名为"image.bmp"并与程序文件放在同一目录下。