jpeg.c

一个已经移植到嵌入式平台上的图象处理程序源代码,可以处理gif,bmp,jpg,png

/*
    fbv  --  simple image viewer for the linux framebuffer
    Copyright (C) 2000, 2001, 2003  Mateusz Golicz

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "config.h"
#ifdef FBV_SUPPORT_JPEG
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <jpeglib.h>
#include <setjmp.h>
#include <unistd.h>
#include <string.h>
#include "fbv.h"

struct r_jpeg_error_mgr
{
	struct jpeg_error_mgr pub;
	jmp_buf envbuffer;
};


int fh_jpeg_id(char *name)
{
	int fd;
	unsigned char id[10];
	fd=open(name,O_RDONLY); 
	if(fd==-1) 
		return(0);
	read(fd,id,10);
	close(fd);
	if(id[6]=='J' && id[7]=='F' && id[8]=='I' && id[9]=='F') 
		return(1);
	if(id[0]==0xff && id[1]==0xd8 && id[2]==0xff) 
		return(1);
	return(0);
}
			    

void jpeg_cb_error_exit(j_common_ptr cinfo)
{
	struct r_jpeg_error_mgr *mptr;
	mptr=(struct r_jpeg_error_mgr*) cinfo->err;
	(*cinfo->err->output_message) (cinfo);
	longjmp(mptr->envbuffer,1);
}

int fh_jpeg_load(char *filename,unsigned char *buffer, unsigned char ** alpha, int x,int y)
{
	struct jpeg_decompress_struct cinfo;
	struct jpeg_decompress_struct *ciptr;
	struct r_jpeg_error_mgr emgr;
	unsigned char *bp;
	int px,py,c;
	FILE *fh;
	JSAMPLE *lb;
	ciptr=&cinfo;
	if(!(fh=fopen(filename,"rb"))) 
		return(FH_ERROR_FILE);
	ciptr->err=jpeg_std_error(&emgr.pub);
	emgr.pub.error_exit=jpeg_cb_error_exit;
	if(setjmp(emgr.envbuffer)==1)
	{
		jpeg_destroy_decompress(ciptr);
		fclose(fh);
		return(FH_ERROR_FORMAT);
	}
	jpeg_create_decompress(ciptr);
	jpeg_stdio_src(ciptr,fh);
	jpeg_read_header(ciptr,TRUE);
	ciptr->out_color_space=JCS_RGB;
	jpeg_start_decompress(ciptr);
	px=ciptr->output_width; py=ciptr->output_height;
	c=ciptr->output_components;
	if(c==3)
	{
		lb=(*ciptr->mem->alloc_small)((j_common_ptr) ciptr,JPOOL_PERMANENT,c*px);
		bp=buffer;
		while (ciptr->output_scanline < ciptr->output_height)
		{
			jpeg_read_scanlines(ciptr, &lb, 1);
			memcpy(bp,lb,px*c);
			bp+=px*c;
		}					   
	}
	jpeg_finish_decompress(ciptr);
	jpeg_destroy_decompress(ciptr);
	fclose(fh);
	return(FH_ERROR_OK);
}

int fh_jpeg_getsize(char *filename,int *x,int *y)
{
	struct jpeg_decompress_struct cinfo;
	struct jpeg_decompress_struct *ciptr;
	struct r_jpeg_error_mgr emgr;
	int px,py,c;
	FILE *fh;
	ciptr=&cinfo;
	if(!(fh=fopen(filename,"rb"))) 
		return(FH_ERROR_FILE);
	ciptr->err=jpeg_std_error(&emgr.pub);
	emgr.pub.error_exit=jpeg_cb_error_exit;
	if(setjmp(emgr.envbuffer)==1)
	{
		jpeg_destroy_decompress(ciptr);
		fclose(fh);
		return(FH_ERROR_FORMAT);
	}
	jpeg_create_decompress(ciptr);
	jpeg_stdio_src(ciptr,fh);
	jpeg_read_header(ciptr,TRUE);
	ciptr->out_color_space=JCS_RGB;
	jpeg_start_decompress(ciptr);
	px=ciptr->output_width; py=ciptr->output_height;
	c=ciptr->output_components;
	*x=px; *y=py;
	jpeg_destroy_decompress(ciptr);
	fclose(fh);
	return(FH_ERROR_OK);
}

void write_JPEG_file(struct image *i)
{
    struct jpeg_compress_struct cinfo;
    struct jpeg_error_mgr               jerr;
    FILE                *outfile;
    JSAMPROW        row_pointer[1];
    int                 row_stride;
    cinfo.err = jpeg_std_error(&jerr);
    jpeg_create_compress(&cinfo);
  if ((outfile = fopen(i->filename, "wb")) == NULL)
  {
    fprintf(stderr, "can't open %s\n", i->filename);
    return;
  }
  jpeg_stdio_dest(&cinfo, outfile);
  cinfo.image_width = i->width;
  cinfo.image_height = i->height;
  cinfo.input_components = 3;
  cinfo.in_color_space = JCS_RGB;
  jpeg_set_defaults(&cinfo);
  jpeg_set_quality(&cinfo, 75, TRUE);
  jpeg_start_compress(&cinfo, TRUE);
  row_stride = i->width * 3;
  while (cinfo.next_scanline < cinfo.image_height)
  {
    row_pointer[0] = &(i->rgb[cinfo.next_scanline * row_stride]);
    (void)jpeg_write_scanlines(&cinfo, row_pointer, 1);
  }
  jpeg_finish_compress(&cinfo);
  fclose(outfile);
  jpeg_destroy_compress(&cinfo);
}


#endif