jpeg.c

SMDK2410开发板LINUX下的JPEG图片显示程序。

/*
 * JoTV - Video Streaming Systems
 *
 * jpeg.c - output image to the jpeg files
 * (c) 2001 Jollen <[e-mail]>
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#include <fcntl.h>
#include <unistd.h>
#include <ctype.h>
#include <jpeglib.h>
#include <jerror.h>
#include <jconfig.h>
#include <pthread.h>
#include <sys/param.h>
#include <sys/types.h>

int read_jpeg(const char *filename, int *width, int *height,
			unsigned char **rgb)
{
	struct jpeg_decompress_struct	cinfo;
	struct jpeg_error_mgr		jerr;
	unsigned char			*ptr = NULL;
	int				i, ipos;
	FILE				*infile;

	if ((infile = fopen(filename, "rb")) == NULL)
	{
		fprintf(stderr, "Cannot open input JPEG file: %s\n", filename);
		return -1;
	}

	cinfo.err = jpeg_std_error(&jerr);
	jpeg_create_decompress(&cinfo);
	jpeg_stdio_src(&cinfo, infile);
	jpeg_read_header(&cinfo, TRUE);
	jpeg_start_decompress(&cinfo);

	*width = cinfo.output_width;
	*height = cinfo.output_height;

	*rgb = malloc(3 * cinfo.output_width * cinfo.output_height);

	if ((*rgb) == NULL)
	{
		fprintf(stderr, "Cannot allocate memory for JPEG file.\n");
		fclose(infile);
		return -1;
	}

	if (cinfo.output_components == 3)
	{
		ptr = (*rgb);
		while (cinfo.output_scanline < cinfo.output_height) 
		{
			jpeg_read_scanlines(&cinfo, &ptr, 1);
			ptr += 3 * cinfo.output_width;
		}
	}
	else if (cinfo.output_components == 1)
	{
		ptr = malloc(cinfo.output_width);
		if (ptr == NULL)
		{
			fprintf(stderr, "Cannot allocate memory for JPEG file.\n");
			fclose(infile);
			return -1;
		}

		ipos = 0;

		while (cinfo.output_scanline < cinfo.output_height) 
		{
			jpeg_read_scanlines(&cinfo, &ptr, 1);

			for (i = 0; i < cinfo.output_width; i++)
			{
				memset((*rgb) + ipos, ptr[i], 3);
				ipos += 3;
			}
		}

		free(ptr);
	}

	jpeg_finish_decompress(&cinfo);
	jpeg_destroy_decompress(&cinfo);

	fclose(infile);

	return 0;
}