#include <stdio.h>
#include "jpeglib.h"
#include <setjmp.h>/*
Allocate and initialize a JPEG decompression object    // 分配和初始化一个decompression结构体
Specify the source of the compressed data (eg, a file) // 指定源文件
Call jpeg_read_header() to obtain image info           // 用jpeg_read_header获得jpg信息
Set parameters for decompression                       // 设置解压参数,比如放大、缩小
jpeg_start_decompress(...);                            // 启动解压：jpeg_start_decompress
while (scan lines remain to be read)jpeg_read_scanlines(...);                           // 循环调用jpeg_read_scanlines
jpeg_finish_decompress(...);                           // jpeg_finish_decompress
Release the JPEG decompression object                   // 释放decompression结构体
*//* Uage: jpg2rgb <jpg_file>*/int main(int argc, char **argv)
{struct jpeg_decompress_struct cinfo;struct jpeg_error_mgr jerr;FILE * infile;// 分配和初始化一个decompression结构体cinfo.err = jpeg_std_error(&jerr);jpeg_create_decompress(&cinfo);// 指定源文件if ((infile = fopen(argv[1], "rb")) == NULL) {fprintf(stderr, "can't open %s\n", argv[1]);return -1;}jpeg_stdio_src(&cinfo, infile);// 用jpeg_read_header获得jpg信息jpeg_read_header(&cinfo, TRUE);/* 源信息 */printf("image_width    = %d\n", cinfo.image_width);printf("image_height   = %d\n", cinfo.image_height);printf("num_components = %d\n", cinfo.num_components);// 设置解压参数,比如放大、缩小// 启动解压：jpeg_start_decompressjpeg_start_decompress(&cinfo);/* 输出的图像信息 */printf("output_width   = %d\n", cinfo.output_width);printf("output_height  = %d\n", cinfo.output_height);printf("output_components = %d\n", cinfo.output_components);// 循环调用jpeg_read_scanlines一行一行的获得解压数据
jpeg_finish_decompress(&cinfo);jpeg_destroy_decompress(&cinfo);return 0;
}

#include <stdio.h>
#include "jpeglib.h"
#include <setjmp.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <linux/fb.h>
#include <string.h>#define FB_DEVICE_NAME "/dev/fb0"
#define DBG_PRINTF     printfstatic int g_fd;static struct fb_var_screeninfo g_tFBVar;
static struct fb_fix_screeninfo g_tFBFix;
static unsigned char *g_pucFBMem;
static unsigned int g_dwScreenSize;static unsigned int g_dwLineWidth;
static unsigned int g_dwPixelWidth;static int FBDeviceInit(void)
{int ret;g_fd = open(FB_DEVICE_NAME, O_RDWR);if (0 > g_fd){DBG_PRINTF("can't open %s\n", FB_DEVICE_NAME);}ret = ioctl(g_fd, FBIOGET_VSCREENINFO, &g_tFBVar);if (ret < 0){DBG_PRINTF("can't get fb's var\n");return -1;}ret = ioctl(g_fd, FBIOGET_FSCREENINFO, &g_tFBFix);if (ret < 0){DBG_PRINTF("can't get fb's fix\n");return -1;}g_dwScreenSize = g_tFBVar.xres * g_tFBVar.yres * g_tFBVar.bits_per_pixel / 8;g_pucFBMem = (unsigned char *)mmap(NULL , g_dwScreenSize, PROT_READ | PROT_WRITE, MAP_SHARED, g_fd, 0);if (0 > g_pucFBMem)    {DBG_PRINTF("can't mmap\n");return -1;}
/*g_tFBOpr.iXres       = g_tFBVar.xres;g_tFBOpr.iYres       = g_tFBVar.yres;g_tFBOpr.iBpp        = g_tFBVar.bits_per_pixel;
*/g_dwLineWidth  = g_tFBVar.xres * g_tFBVar.bits_per_pixel / 8;g_dwPixelWidth = g_tFBVar.bits_per_pixel / 8;return 0;
}static int FBShowPixel(int iX, int iY, unsigned int dwColor)
{unsigned char *pucFB;unsigned short *pwFB16bpp;unsigned int *pdwFB32bpp;unsigned short wColor16bpp; /* 565 */int iRed;int iGreen;int iBlue;if ((iX >= g_tFBVar.xres) || (iY >= g_tFBVar.yres)){DBG_PRINTF("out of region\n");return -1;}pucFB      = g_pucFBMem + g_dwLineWidth * iY + g_dwPixelWidth * iX;pwFB16bpp  = (unsigned short *)pucFB;pdwFB32bpp = (unsigned int *)pucFB;switch (g_tFBVar.bits_per_pixel){case 8:{*pucFB = (unsigned char)dwColor;break;}case 16:{iRed   = (dwColor >> (16+3)) & 0x1f;iGreen = (dwColor >> (8+2)) & 0x3f;iBlue  = (dwColor >> 3) & 0x1f;wColor16bpp = (iRed << 11) | (iGreen << 5) | iBlue;*pwFB16bpp    = wColor16bpp;break;}case 32:{*pdwFB32bpp = dwColor;break;}default :{DBG_PRINTF("can't support %d bpp\n", g_tFBVar.bits_per_pixel);return -1;}}return 0;
}static int FBCleanScreen(unsigned int dwBackColor)
{unsigned char *pucFB;unsigned short *pwFB16bpp;unsigned int *pdwFB32bpp;unsigned short wColor16bpp; /* 565 */int iRed;int iGreen;int iBlue;int i = 0;pucFB      = g_pucFBMem;pwFB16bpp  = (unsigned short *)pucFB;pdwFB32bpp = (unsigned int *)pucFB;switch (g_tFBVar.bits_per_pixel){case 8:{memset(g_pucFBMem, dwBackColor, g_dwScreenSize);break;}case 16:{iRed   = (dwBackColor >> (16+3)) & 0x1f;iGreen = (dwBackColor >> (8+2)) & 0x3f;iBlue  = (dwBackColor >> 3) & 0x1f;wColor16bpp = (iRed << 11) | (iGreen << 5) | iBlue;while (i < g_dwScreenSize){*pwFB16bpp    = wColor16bpp;pwFB16bpp++;i += 2;}break;}case 32:{while (i < g_dwScreenSize){*pdwFB32bpp    = dwBackColor;pdwFB32bpp++;i += 4;}break;}default :{DBG_PRINTF("can't support %d bpp\n", g_tFBVar.bits_per_pixel);return -1;}}return 0;
}static int FBShowline(int iXStart, int iXEnd, int iY, unsigned char *pucRGBArray)
{int i = iXStart * 3;    //每个像素占据三个字节int iX;unsigned int dwColor;if(iY >= g_tFBVar.yres)return -1;if(iXStart>= g_tFBVar.xres)return -1;if((iXEnd >= g_tFBVar.xres)){iXEnd = g_tFBVar.xres;    }for(iX = iXStart; iX < iXEnd; iX++){/* 0xRRGGBB */dwColor = (pucRGBArray[i] << 16 ) + (pucRGBArray[i + 1] << 8) + (pucRGBArray[i + 2] << 0);i += 3;FBShowPixel(iX, iY, dwColor);}return 0;
}/*
Allocate and initialize a JPEG decompression object    // 分配和初始化一个decompression结构体
Specify the source of the compressed data (eg, a file) // 指定源文件
Call jpeg_read_header() to obtain image info           // 用jpeg_read_header获得jpg信息
Set parameters for decompression                       // 设置解压参数,比如放大、缩小
jpeg_start_decompress(...);                            // 启动解压：jpeg_start_decompress
while (scan lines remain to be read)jpeg_read_scanlines(...);                           // 循环调用jpeg_read_scanlines
jpeg_finish_decompress(...);                           // jpeg_finish_decompress
Release the JPEG decompression object                   // 释放decompression结构体
*//* Uage: jpg2rgb <jpg_file>*/int main(int argc, char **argv)
{struct jpeg_decompress_struct cinfo;struct jpeg_error_mgr jerr;FILE * infile;int  row_stride; unsigned char *buffer;if(FBDeviceInit()){return -1;}FBCleanScreen(0);// 分配和初始化一个decompression结构体cinfo.err = jpeg_std_error(&jerr);jpeg_create_decompress(&cinfo);// 指定源文件if ((infile = fopen(argv[1], "rb")) == NULL) {fprintf(stderr, "can't open %s\n", argv[1]);return -1;}jpeg_stdio_src(&cinfo, infile);// 用jpeg_read_header获得jpg信息jpeg_read_header(&cinfo, TRUE);/* 源信息 */printf("image_width    = %d\n", cinfo.image_width);printf("image_height   = %d\n", cinfo.image_height);printf("num_components = %d\n", cinfo.num_components);// 设置解压参数,比如放大、缩小printf("enter M/N: \n");scanf("%d/%d", &cinfo.scale_num, &cinfo.scale_denom);printf("scale to : %d/%d\n", cinfo.scale_num, cinfo.scale_denom);// 启动解压：jpeg_start_decompressjpeg_start_decompress(&cinfo);/* 输出的图像信息 */printf("output_width   = %d\n", cinfo.output_width);printf("output_height  = %d\n", cinfo.output_height);printf("output_components = %d\n", cinfo.output_components);//一行的数据长度row_stride = cinfo.output_width * cinfo.output_components; buffer  = malloc(row_stride);// 循环调用jpeg_read_scanlines一行一行的获得解压数据while (cinfo.output_scanline < cinfo.output_height) {(void) jpeg_read_scanlines(&cinfo, &buffer, 1);//写到LCD去FBShowline(0, cinfo.output_width, cinfo.output_scanline, buffer);}free(buffer);jpeg_finish_decompress(&cinfo);jpeg_destroy_decompress(&cinfo);return 0;
}