mga_jpg.c

linux下显示各种格式图片

/* 	(c) HelDoRe
	Jpeg unit ...   v0.0.5
			Supported formats :
			libjpeg
*/			

#define VERJPG " unit v0.0.5"

#include <stdio.h>
#include "../mga_view.h"
#ifdef USE_LIBJPG
#include <jpeglib.h>
#include <setjmp.h>
#endif


void help_jpg()


{
#ifdef USE_LIBJPG
printf("JPG%s\n   + uses libjpeg\n",VERJPG);
#endif
}



#ifdef USE_LIBJPG
struct my_error_mgr {
    struct jpeg_error_mgr pub;
	jmp_buf setjmp_buffer;
};

typedef struct my_error_mgr * my_error_ptr;


METHODDEF(void) my_error_exit(j_common_ptr cinfo)
    {
    my_error_ptr myerr = (my_error_ptr) cinfo->err;
    (*cinfo->err->output_message)(cinfo);
    longjmp(myerr->setjmp_buffer,1);
    }
#endif
    




int detect_jpg()
{
#ifdef USE_LIBJPG

    short int JPsyg;
    struct jpeg_decompress_struct cinfo;
    struct my_error_mgr jerr;
    JSAMPARRAY buffer;
    int row_stride,jaka;

	fread(&JPsyg,sizeof (short int),1,plik);
	    if (JPsyg != -9985) {
	    return 1;
	    }
	    rewind(plik);
    cinfo.err = jpeg_std_error(&jerr.pub);
    jerr.pub.error_exit = my_error_exit;

    if (setjmp(jerr.setjmp_buffer)) {
	jpeg_destroy_decompress(&cinfo);
	return 2;
	}
	
    
    jpeg_create_decompress(&cinfo);
    jpeg_stdio_src(&cinfo,plik);    
    (void) jpeg_read_header(&cinfo,TRUE);
    (void) jpeg_start_decompress(&cinfo);    

	    image_x=cinfo.output_width;
	    image_y=cinfo.output_height;
	    jaka=cinfo.num_components;
	    check_image(image_x,image_y,8);
	    printf("Jpeg%s\n",VERJPG);
	    printf("Jpeg detected   : %ix%i ",image_x,image_y);
	    if (jaka==3) printf("color\n"); else printf("grayscale\n");

	    row_stride=cinfo.output_width*cinfo.output_components;
	    buffer=(*cinfo.mem->alloc_sarray)((j_common_ptr) &cinfo,JPOOL_IMAGE,row_stride,1);
	    y=0;
	    while (cinfo.output_scanline <cinfo.output_height) {
	    
		    (void) jpeg_read_scanlines(&cinfo,buffer,1);
			if (jaka==3)  
			for (x=0;x<image_x;x++)
		            {
			    tabr[x+y*image_x]=buffer[0][x*3];
			    tabg[x+y*image_x]=buffer[0][x*3+1];
			    tabb[x+y*image_x]=buffer[0][x*3+2];

			    } else 

			for (x=0;x<image_x;x++)
		            {
			    tabr[x+y*image_x]=buffer[0][x];
			    tabg[x+y*image_x]=tabr[x+y*image_x];
			    tabb[x+y*image_x]=tabr[x+y*image_x];

			    } 

			y++;	    
			}
    (void) jpeg_finish_decompress(&cinfo);
    jpeg_destroy_decompress(&cinfo);
    rewind(plik);
    fseek(plik,20,SEEK_CUR);
    tempi=fgetc(plik);
    if ((tempi==255) && (fgetc(plik)==254)) {
	fprintf(stderr,"Comment         : ");
	tempi=fgetc(plik);
	tempi=fgetc(plik);
    	for (x=0;x<tempi-2;x++) {	
	    printf("%c",(char)depth=fgetc(plik));
	    }
	printf("\n");
	}

    return 0;	
#else
    return 1;
#endif

}