将jpeg图片显示在framebuffer上

/**************************************************
 * example5.c
 * Author: T-bagwell
 *
 * Compile:gcc -Wall example5.c -o example5
 *************************************************/
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <linux/fb.h>
#include <errno.h>
#include <sys/mman.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <jpeglib.h>
#include <jerror.h>


int print_screen(short *buf,int width,int height);
void draw_hline(short *buffer,int x,int y,int maxy,int maxx);

char *fb_addr;
unsigned int fb_width;
unsigned int fb_height;
unsigned int fb_depth;
unsigned fb_size;

unsigned short PIXELRGB888TO565(unsigned char red, unsigned char green, unsigned char blue)
{
        unsigned short  B = (blue >> 3) & 0x001F;
        unsigned short  G = ((green >> 3) << 5) & 0x07E0;
        unsigned short  R = ((red >> 3) << 11) & 0xF800;

        return (unsigned short) (R | G | B);
}

int draw_pixel(void *fbmem, int width, int height, int x, int y, unsigned short color)
{
        if ((x > width) || (y > height))
                return -1;

        unsigned short *dst = ((unsigned short *) fbmem + y * width + x);

        *dst = color;
        return (0);
}


int main(int argc, char *argv[])
{
        int screen_fbd=0;
        struct jpeg_decompress_struct cinfo;
        struct jpeg_error_mgr jerr;
        FILE *infile;
        struct fb_fix_screeninfo fb_fix;
        struct fb_var_screeninfo fb_var;
        char *env=NULL;
        unsigned char *buffer;
        unsigned char *fbmem;
        short *color_white;
        unsigned short  color;
        unsigned int x;
        unsigned int y;
        if ((infile = fopen(argv[1], "rb")) == NULL)
        {
                fprintf(stderr, "open bbs.chinaffmpeg.com 孙悟空提醒您 %s failed\n", argv[1]);
                exit(-1);
        }

        if(!(env = getenv("FRAMEBUFFER")))
        {
                env = "/dev/fb0";
        }

        screen_fbd = open(env, O_RDWR);

        if(screen_fbd < 0)
        {
                return 0;
        }

        if(ioctl(screen_fbd, FBIOGET_VSCREENINFO, &fb_var) == -1)
        {
                close(screen_fbd);
                return 0;
        }
        fb_width = fb_var.xres;
        fb_height = fb_var.yres;
        fb_depth = fb_var.bits_per_pixel;

        cinfo.err = jpeg_std_error(&jerr);
        jpeg_create_decompress(&cinfo);

        jpeg_stdio_src(&cinfo, infile);
        jpeg_read_header(&cinfo, TRUE);
        jpeg_start_decompress(&cinfo);
        if ((cinfo.output_width > fb_width) ||(cinfo.output_height > fb_height))
        {
                return (-1);
        }

        fbmem = mmap(0, fb_width * fb_height, PROT_READ | PROT_WRITE, MAP_SHARED, screen_fbd, 0);
        buffer = (unsigned char *) malloc(cinfo.output_width * cinfo.output_components);
        y = 0;

        while (cinfo.output_scanline < cinfo.output_height)
        {
                jpeg_read_scanlines(&cinfo, &buffer, 1);
                if (fb_depth == 16)
                {
                        for (x = 0; x < cinfo.output_width; x++)
                        {
                                color = PIXELRGB888TO565(buffer[x * 3], buffer[x * 3 + 1], buffer[x * 3 + 2]);
                                draw_pixel(fbmem, fb_width, fb_height, x, y, color);
                        }
                }
        y++;
        }
        jpeg_finish_decompress(&cinfo);
        jpeg_destroy_decompress(&cinfo);

        free(buffer);
        return 0;
}

QQ群里突然有人问了这个问题，希望得到开源的程序，正好以前写过一个，找的挺费劲的，就贴到这里吧