jpeg.c

#include "config.h"

#ifdef FBV_SUPPORT_JPEG
#include "fbv.h"
#include <stdio.h>
#include <string.h>
#include <jpeglib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <setjmp.h>
#include <unistd.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, 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))
	{
		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;
	c = ciptr->output_components;

	if(c==3)
	{
		lb = (JSAMPLE*)(*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;
	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))
	{
		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;
	*x = px;
	*y = py;
	jpeg_destroy_decompress(ciptr);
	fclose(fh);
	return(FH_ERROR_OK);
}
#endif /*FBV_SUPPORT_JPEG*/