bmp_show_framebuffer

bmp_show_framebuffer.c

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

//14byte文件头
typedef struct
{
    char cfType[2];  //文件类型，"BM"(0x4D42)
    int  cfSize;     //文件大小（字节）
    int  cfReserved; //保留，值为0
    int  cfoffBits;  //数据区相对于文件头的偏移量（字节）
}__attribute__((packed)) BITMAPFILEHEADER;
//__attribute__((packed))的作用是告诉编译器取消结构在编译过程中的优化对齐

//40byte信息头
typedef struct
{
    char ciSize[4];          //BITMAPFILEHEADER所占的字节数
    int  ciWidth;            //宽度
    int  ciHeight;           //高度
    char ciPlanes[2];        //目标设备的位平面数，值为1
    int  ciBitCount;         //每个像素的位数
    char ciCompress[4];      //压缩说明
    char ciSizeImage[4];     //用字节表示的图像大小，该数据必须是4的倍数
    char ciXPelsPerMeter[4]; //目标设备的水平像素数/米
    char ciYPelsPerMeter[4]; //目标设备的垂直像素数/米
    char ciClrUsed[4];       //位图使用调色板的颜色数
    char ciClrImportant[4];  //指定重要的颜色数，当该域的值等于颜色数时（或者等于0时），表示所有颜色都一样重要
}__attribute__((packed)) BITMAPINFOHEADER;

typedef struct
{
    unsigned char blue;
    unsigned char green;
    unsigned char red;
    unsigned char reserved;
}__attribute__((packed)) PIXEL; //颜色模式RGB



typedef struct
{
    int          fbfd;
    char         *fbp;
    unsigned int xres;
    unsigned int yres;
    unsigned int xres_virtual;
    unsigned int yres_virtual;
    unsigned int xoffset;
    unsigned int yoffset;
    unsigned int bpp;
    unsigned long line_length;
    unsigned long size;

    struct fb_bitfield red;
    struct fb_bitfield green;
    struct fb_bitfield blue;
} FB_INFO;

typedef struct
{
    unsigned int width;
    unsigned int height;
    unsigned int bpp;
    unsigned long size;
    unsigned int data_offset;
} IMG_INFO;



FB_INFO fb_info;
IMG_INFO img_info;

int show_bmp(char *img_name);

static int cursor_bitmap_format_convert(char *dst,char *src, unsigned long img_len_one_line)
{
    int img_len ,fb_len ;
    char *p;
    __u32 val;
    PIXEL pix;

    p = (char *)&val;

    img_len = img_info.width; /*一行图片的长度*/
    fb_len = fb_info.xres; /*一行显示屏的长度*/

    /*进行x轴的偏移*/
    dst += fb_info.xoffset * (fb_info.bpp / 8);
    fb_len -= fb_info.xoffset;

    /*bmp 数据是上下左右颠倒的，这里只进行左右的处理*/
    /*先定位到图片的最后一个像素的地址，然后往第一个像素的方向处理，进行左右颠倒的处理*/
    src += img_len_one_line - 1;

    /*处理一行要显示的数据*/
    while(1) {
        if (img_info.bpp == 32)
            pix.reserved = *(src--);
        pix.red   = *(src--);
        pix.green = *(src--);
        pix.blue  = *(src--);

        val = 0x00;
        val |= (pix.red >> (8 - fb_info.red.length)) << fb_info.red.offset;
        val |= (pix.green >> (8 - fb_info.green.length)) << fb_info.green.offset;
        val |= (pix.blue >> (8 - fb_info.blue.length)) << fb_info.blue.offset;


        if (fb_info.bpp == 16) {
            *(dst++) = *(p + 0);
            *(dst++) = *(p + 1);
        }
        else if (fb_info.bpp == 24) {
            *(dst++) = *(p + 0);
            *(dst++) = *(p + 1);
            *(dst++) = *(p + 2);
        }
        else if (fb_info.bpp == 32) {
            *(dst++) = *(p + 0);
            *(dst++) = *(p + 1);
            *(dst++) = *(p + 2);
            *(dst++) = *(p + 3);
        }

        /*超过图片长度或显示屏长度认为一行处理完了*/
        img_len--;
        fb_len--;
        if (img_len <= 0 || fb_len <= 0)
            break;
    }
#if 0
    printf("r = %d\n", pix.red);
    printf("g = %d\n", pix.green);
    printf("b = %d\n", pix.blue);
#endif
    return 0;
}

int show_bmp(char *img_name)
{

    FILE *fp;
    int ret = 0;
    BITMAPFILEHEADER FileHead;
    BITMAPINFOHEADER InfoHead;

    if(img_name == NULL) {
        printf("img_name is null\n");
        return -1;
    }

    fp = fopen( img_name, "rb" );
    if(fp == NULL) {
        printf("img[%s] open failed\n", img_name);
        ret = -1;
        goto err_showbmp;
    }

    /* 移位到文件头部 */
    fseek(fp, 0, SEEK_SET);

    ret = fread(&FileHead, sizeof(BITMAPFILEHEADER), 1, fp);
    if ( ret != 1) {
        printf("img read failed\n");
        ret = -1;
        goto err_showbmp;
    }

    //检测是否是bmp图像
    if (memcmp(FileHead.cfType, "BM", 2) != 0) {
        printf("it's not a BMP file[%c%c]\n", FileHead.cfType[0], FileHead.cfType[1]);
        ret = -1;
        goto err_showbmp;
    }

    ret = fread( (char *)&InfoHead, sizeof(BITMAPINFOHEADER),1, fp );
    if ( ret != 1) {
        printf("read infoheader error!\n");
        ret = -1;
        goto err_showbmp;
    }

    img_info.width       = InfoHead.ciWidth;
    img_info.height      = InfoHead.ciHeight;
    img_info.bpp         = InfoHead.ciBitCount;
    img_info.size        = FileHead.cfSize;
    img_info.data_offset = FileHead.cfoffBits;

    printf("img info w[%d] h[%d] bpp[%d] size[%ld] offset[%d]\n", img_info.width, img_info.height, img_info.bpp, img_info.size, img_info.data_offset);

    if (img_info.bpp != 24 && img_info.bpp != 32) {
        printf("img bpp is not 24 or 32\n");
        ret = -1;
        goto err_showbmp;
    }


    /*
     *一行行处理
     */
    char *buf_img_one_line;
    char *buf_fb_one_line;
    char *p;
    int fb_height;

    long img_len_one_line = img_info.width * (img_info.bpp / 8);
    long fb_len_one_line = fb_info.line_length;

    printf("img_len_one_line = %d\n", img_len_one_line);
    printf("fb_len_one_line = %d\n", fb_info.line_length);

    buf_img_one_line = (char *)calloc(1, img_len_one_line + 256);
    if(buf_img_one_line == NULL) {
        printf("alloc failed\n");
        ret = -1;
        goto err_showbmp;
    }

    buf_fb_one_line = (char *)calloc(1, fb_len_one_line + 256);
    if(buf_fb_one_line == NULL) {
        printf("alloc failed\n");
        ret = -1;
        goto err_showbmp;
    }


    fseek(fp, img_info.data_offset, SEEK_SET);

    p = fb_info.fbp + fb_info.yoffset * fb_info.line_length; /*进行y轴的偏移*/
    fb_height = fb_info.yres;
    while (1) {
        memset(buf_img_one_line, 0, img_len_one_line);
        memset(buf_fb_one_line, 0, fb_len_one_line);
        ret = fread(buf_img_one_line, 1, img_len_one_line, fp);
        if (ret < img_len_one_line) {
            /*图片读取完成，则图片显示完成*/
            printf("read to end of img file\n");
            cursor_bitmap_format_convert(buf_fb_one_line, buf_img_one_line, img_len_one_line); /*数据转换*/
            memcpy(fb_info.fbp, buf_fb_one_line, fb_len_one_line);
            break;
        }

        cursor_bitmap_format_convert(buf_fb_one_line, buf_img_one_line, img_len_one_line); /*数据转换*/
        memcpy(p, buf_fb_one_line, fb_len_one_line); /*显示一行*/
        p += fb_len_one_line;

        /*超过显示屏宽度认为图片显示完成*/
        fb_height--;
        if (fb_height <= 0)
            break;
    }

    free(buf_img_one_line);
    free(buf_fb_one_line);

    fclose(fp);
    return ret;
err_showbmp:
    if (fp)
        fclose(fp);
    return ret;
}

int show_picture(char *img_name)
{
    struct fb_var_screeninfo vinfo;
    struct fb_fix_screeninfo finfo;

    if (fb_info.fbfd <= -1) {
        printf("fb open fialed\n");
        return -1;
    }

    if (ioctl(fb_info.fbfd, FBIOGET_FSCREENINFO, &finfo)) {
        printf("fb ioctl fialed\n");
        return -1;
    }

    if (ioctl(fb_info.fbfd, FBIOGET_VSCREENINFO, &vinfo)) {
        printf("fb ioctl fialed\n");
        return -1;
    }

    fb_info.xres = vinfo.xres;
    fb_info.yres = vinfo.yres;
    fb_info.xres_virtual = vinfo.xres_virtual;
    fb_info.yres_virtual = vinfo.yres_virtual;
    fb_info.xoffset = vinfo.xoffset;
    fb_info.yoffset = vinfo.yoffset;
    fb_info.bpp  = vinfo.bits_per_pixel;
    fb_info.line_length = finfo.line_length;
    fb_info.size = finfo.smem_len;

    memcpy(&fb_info.red, &vinfo.red, sizeof(struct fb_bitfield));
    memcpy(&fb_info.green, &vinfo.green, sizeof(struct fb_bitfield));
    memcpy(&fb_info.blue, &vinfo.blue, sizeof(struct fb_bitfield));

    printf("fb info x[%d] y[%d] x_v[%d] y_v[%d] xoffset[%d] yoffset[%d] bpp[%d] line_length[%ld] size[%ld]\n", fb_info.xres, fb_info.yres, fb_info.xres_virtual, fb_info.yres_virtual, fb_info.xoffset, fb_info.yoffset, fb_info.bpp, fb_info.line_length, fb_info.size);

    printf("fb info red off[%d] len[%d] msb[%d]\n", fb_info.red.offset, fb_info.red.length, fb_info.red.msb_right);
    printf("fb info green off[%d] len[%d] msb[%d]\n", fb_info.green.offset, fb_info.green.length, fb_info.green.msb_right);
    printf("fb info blue off[%d] len[%d] msb[%d]\n", fb_info.blue.offset, fb_info.blue.length, fb_info.blue.msb_right);

    if (fb_info.bpp != 16 && fb_info.bpp != 24 && fb_info.bpp != 32) {
        printf("fb bpp is not 16,24 or 32\n");
        return -1;
    }

    if (fb_info.red.length > 8 || fb_info.green.length > 8 || fb_info.blue.length > 8) {
        printf("fb red|green|blue length is invalid\n");
        return -1;
    }

    // 内存映射
    fb_info.fbp = (char *)mmap(0, fb_info.size, PROT_READ | PROT_WRITE, MAP_SHARED, fb_info.fbfd, 0);
    if (fb_info.fbp == (char *)-1) {
        printf("mmap fialed\n");
        return -1;
    }

    show_bmp(img_name);
    
    //删除映射
    munmap(fb_info.fbp, fb_info.size);

    return 0;
}


int main(int argc, char **argv)
{
    char img_name[64];

    if (argc != 2) {
        printf("arg error\n");
        return 0;
    }

    snprintf(img_name, sizeof(img_name), "%s", argv[1]);
    printf("img_name = %s\n", img_name);

    fb_info.fbfd = open("/dev/fb0", O_RDWR);
    if (!fb_info.fbfd) {
        printf("Error: cannot open framebuffer device(/dev/fb0).\n");
        return -1;
    }
    
       show_picture(img_name);
    

       close(fb_info.fbfd);
        return 0;
}