/* * $Id: fv.c * $Desp: draw jpeg to framebuffer * $Author: rockins * $Date: Wed Jan  3 20:15:49 CST 2007 */#include <stdio.h>#include <stdlib.h>#include <fcntl.h>#include <linux/fb.h>#include <sys/types.h>#include <sys/stat.h>#include <sys/mman.h>#include <jpeglib.h>#include <jerror.h>#define	FB_DEV	"/dev/fb0"/***************** function declaration ******************/void            usage(char *msg);unsigned short  RGB888toRGB565(unsigned char red,							   unsigned char green, unsigned char blue);int             fb_open(char *fb_device);int             fb_close(int fd);int             fb_stat(int fd, int *width, int *height, int *depth);void           *fb_mmap(int fd, unsigned int screensize);int             fb_munmap(void *start, size_t length);int             fb_pixel(void *fbmem, int width, int height,						 int x, int y, unsigned short color);/************ function implementation ********************/intmain(int argc, char *argv[]){	/*	 * declaration for jpeg decompression	 */	struct jpeg_decompress_struct cinfo;	struct jpeg_error_mgr jerr;	FILE           *infile;	unsigned char  *buffer;	/*	 * declaration for framebuffer device	 */	int             fbdev;	char           *fb_device;	unsigned char  *fbmem;	unsigned int    screensize;	unsigned int    fb_width;	unsigned int    fb_height;	unsigned int    fb_depth;	unsigned int    x;	unsigned int    y;	/*	 * check auguments	 */	if (argc != 2) {		usage("insuffient auguments");		exit(-1);	}	/*	 * open framebuffer device	 */	if ((fb_device = getenv("FRAMEBUFFER")) == NULL)		fb_device = FB_DEV;	fbdev = fb_open(fb_device);	/*	 * get status of framebuffer device	 */	fb_stat(fbdev, &fb_width, &fb_height, &fb_depth);	/*	 * map framebuffer device to shared memory	 */	screensize = fb_width * fb_height;	fbmem = fb_mmap(fbdev, screensize);	/*	 * open input jpeg file 	 */	if ((infile = fopen(argv[1], "rb")) == NULL) {		fprintf(stderr, "open %s failed\n", argv[1]);		exit(-1);	}	/*	 * init jpeg decompress object error handler	 */	cinfo.err = jpeg_std_error(&jerr);	jpeg_create_decompress(&cinfo);	/*	 * bind jpeg decompress object to infile	 */	jpeg_stdio_src(&cinfo, infile);	/*	 * read jpeg header	 */	jpeg_read_header(&cinfo, TRUE);	/*	 * decompress process.	 * note: after jpeg_start_decompress() is called	 * the dimension infomation will be known,	 * so allocate memory buffer for scanline immediately	 */	jpeg_start_decompress(&cinfo);	if ((cinfo.output_width > fb_width) ||		(cinfo.output_height > fb_height)) {		printf("too large JPEG file,cannot display\n");		return (-1);	}	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) {			unsigned short  color;			for (x = 0; x < cinfo.output_width; x++) {				color = RGB888toRGB565(buffer[x * 3], 						buffer[x * 3 + 1], buffer[x * 3 + 2]);				fb_pixel(fbmem, fb_width, fb_height, x, y, color);			}		} else if (fb_depth == 24) {			memcpy((unsigned char *) fbmem + y * fb_width * 3,				   buffer, cinfo.output_width * cinfo.output_components);		}		y++;					// next scanline	}	/*	 * finish decompress, destroy decompress object	 */	jpeg_finish_decompress(&cinfo);	jpeg_destroy_decompress(&cinfo);	/*	 * release memory buffer	 */	free(buffer);	/*	 * close jpeg inputing file	 */	fclose(infile);	/*	 * unmap framebuffer's shared memory	 */	fb_munmap(fbmem, screensize);	/*	 * close framebuffer device	 */	fb_close(fbdev);	return (0);}voidusage(char *msg){	fprintf(stderr, "%s\n", msg);	printf("Usage: fv some-jpeg-file.jpg\n");}/* * convert 24bit RGB888 to 16bit RGB565 color format */unsigned shortRGB888toRGB565(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);}/* * open framebuffer device. * return positive file descriptor if success, * else return -1. */intfb_open(char *fb_device){	int             fd;	if ((fd = open(fb_device, O_RDWR)) < 0) {		perror(__func__);		return (-1);	}	return (fd);}/* * get framebuffer's width,height,and depth. * return 0 if success, else return -1. */intfb_stat(int fd, int *width, int *height, int *depth){	struct fb_fix_screeninfo fb_finfo;	struct fb_var_screeninfo fb_vinfo;	if (ioctl(fd, FBIOGET_FSCREENINFO, &fb_finfo)) {		perror(__func__);		return (-1);	}	if (ioctl(fd, FBIOGET_VSCREENINFO, &fb_vinfo)) {		perror(__func__);		return (-1);	}	*width = fb_vinfo.xres;	*height = fb_vinfo.yres;	*depth = fb_vinfo.bits_per_pixel;	return (0);}/* * map shared memory to framebuffer device. * return maped memory if success, * else return -1, as mmap dose. */void *fb_mmap(int fd, unsigned int screensize){	void *	fbmem;	if ((fbmem = mmap(0, screensize, PROT_READ | PROT_WRITE,					  MAP_SHARED, fd, 0)) == MAP_FAILED) {		perror(__func__);		return (void *) (-1);	}	return (fbmem);}/* * unmap map memory for framebuffer device. */intfb_munmap(void *start, size_t length){	return (munmap(start, length));}/* * close framebuffer device */intfb_close(int fd){	return (close(fd));}/* * display a pixel on the framebuffer device. * fbmem is the starting memory of framebuffer, * width and height are dimension of framebuffer, * x and y are the coordinates to display, * color is the pixel's color value. * return 0 if success, otherwise return -1. */intfb_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);}