mga_png.c

linux下显示各种格式图片

/* 	(c) HelDoRe
	Png unit ...    v0.0.4
			Supported formats :
			libpng :-)
*/			

#define VERPNG " unit v0.0.4"
#ifndef png_jmpbuf
#  define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf)
#endif
#define PNG_BYTES_TO_CHECK 4

#include <stdio.h>
#include "../mga_view.h"
#ifdef USE_LIBPNG
#include <png.h>
#endif

void help_png()

{
#ifdef USE_LIBPNG
printf("PNG%s\n   + uses libpng\n",VERPNG);
#endif
}

int detect_png()
{
#ifdef USE_LIBPNG
    png_bytep row_pointers[4000];
    int row;
    char buf[PNG_BYTES_TO_CHECK];
    png_structp png_ptr;
    png_infop info_ptr;
    png_uint_32 width,height;
    int bit_depth,color_type,interlace_type;
    
    
    fread(buf,1,PNG_BYTES_TO_CHECK,plik);
    tempi=png_sig_cmp(buf,(png_size_t)0,PNG_BYTES_TO_CHECK);
    if (tempi!=0) return 1;
    rewind(plik);
    png_ptr=png_create_read_struct(PNG_LIBPNG_VER_STRING,
	    NULL,NULL,NULL);
    if (png_ptr==NULL) return 2;
    
    info_ptr=png_create_info_struct(png_ptr);
    if (info_ptr==NULL){
	png_destroy_read_struct(&png_ptr,(png_infopp)NULL,(png_infopp)NULL);
	return 2;
	}

    if (setjmp(png_jmpbuf(png_ptr))){
	png_destroy_read_struct(&png_ptr,&info_ptr,(png_infopp)NULL);
	return 2;
	}
	
    png_init_io(png_ptr,plik);    
    png_read_info(png_ptr,info_ptr);
    png_get_IHDR(png_ptr,info_ptr,&width,&height,&bit_depth,&color_type,&interlace_type,NULL,NULL);

    image_x=width;
    image_y=height;
    depth=bit_depth;
    tempi=png_get_channels(png_ptr,info_ptr);
    check_image(image_x,image_y,depth);
    printf("Png%s\n",VERPNG);
    printf("Png detected    : %ix%ix%i  ch %i\n",image_x,image_y,depth,tempi);

    if (color_type==PNG_COLOR_TYPE_GRAY || color_type==PNG_COLOR_TYPE_GRAY_ALPHA)
	png_set_gray_to_rgb(png_ptr);
    png_set_expand(png_ptr);
    png_read_update_info(png_ptr,info_ptr);
    tempi=png_get_channels(png_ptr,info_ptr);


    for (row=0;row<height;row++){
	row_pointers[row]=png_malloc(png_ptr,png_get_rowbytes(png_ptr,info_ptr));
	}
	    
	png_read_image(png_ptr,row_pointers);
	png_read_end(png_ptr,info_ptr);

			for (y=0;y<image_y;y++) {
		           for (x=0;x<image_x;x++)
		            {
			    tabr[x+y*image_x]=row_pointers[y][x*tempi];
			    tabg[x+y*image_x]=row_pointers[y][x*tempi+1];
			    tabb[x+y*image_x]=row_pointers[y][x*tempi+2];
			    }
		           }
		    
		    
		    
    png_destroy_read_struct(&png_ptr,&info_ptr,(png_infopp)NULL);
    return 0;	
#else
    return 1;
#endif
}