jpeg入门3 在lcd显示图片

#include 
#include "jpeglib.h"
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define FB_DEVICE_NAME "/dev/fb0"
#define DBG_PRINTF printf

static 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_dwLineWidth  = g_tFBVar.xres * g_tFBVar.bits_per_pixel / 8;
	g_dwPixelWidth = g_tFBVar.bits_per_pixel / 8;
	printf("%d",g_tFBVar.bits_per_pixel);
	
	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;
	printf("g_tFBVar.bits_per_pixel=%d\n",g_tFBVar.bits_per_pixel);
	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;
	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;		
	}
	//把配出0xRRGGBB位的 
	for(iX=iXStart;iX\n", argv[0]);
		return -1;
	}
	if(FBDeviceInit())
	{
		return -1;
	}
	FBCleanScreen(0);
	cinfo.err=jpeg_std_error(&jerr);//将错误处理结构对象绑定在JPEG结构体
	jpeg_create_decompress(&cinfo);//创建初始化cinfo结构 
	if((infile=fopen(argv[1],"rb"))==NULL)
	{
		fprintf(stderr,"can't open %s", argv[1]);
		return -1;
	}
	jpeg_stdio_src(&cinfo,infile);
	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);
	
	printf("enter scale 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_decompress	
	jpeg_start_decompress(&cinfo);
	/* 输出的图象的信息 */
	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);
	while(cinfo.output_scanline