jpeg.c

/*
    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)
    {
	// FATAL ERROR - Free the object and return...
	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)
    {
	// FATAL ERROR - Free the object and return...
	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);
}
#endif