ximapng.cpp

用Cximage 库显示各种格式图片小程序

				}

				//read next row
				png_read_row(png_ptr, row_pointers, NULL);

				//shrink 16 bit depth images down to 8 bits
				if (info_ptr->bit_depth > 8){
					for(long ax=0;ax<(head.biWidth*channels);ax++)
						row_pointers[ax] = row_pointers[ax*chan_offset];
				}

				//copy the pixels
				iter.SetRow(row_pointers, info_ptr->rowbytes);
				//<DP> expand 2 bpp images only in the last pass
				if (info_ptr->bit_depth==2 && pass==(number_passes-1))
					expand2to4bpp(iter.GetRow());

				//go on
				iter.PrevRow();
			}

			y++;
		} while(y<head.biHeight);
	}

	delete [] row_pointers;

	/* read the rest of the file, getting any additional chunks in info_ptr */
	png_read_end(png_ptr, info_ptr);

	/* clean up after the read, and free any memory allocated - REQUIRED */
	png_destroy_read_struct(&png_ptr, &info_ptr, (png_infopp)NULL);

  } cx_catch {
	if (strcmp(message,"")) strncpy(info.szLastError,message,255);
	if (info.nEscape == -1 && info.dwType == CXIMAGE_FORMAT_PNG) return true;
	return false;
  }
	/* that's it */
	return true;
}
////////////////////////////////////////////////////////////////////////////////
#endif //CXIMAGE_SUPPORT_DECODE
////////////////////////////////////////////////////////////////////////////////
#if CXIMAGE_SUPPORT_ENCODE
////////////////////////////////////////////////////////////////////////////////
bool CxImagePNG::Encode(CxFile *hFile)
{
	if (EncodeSafeCheck(hFile)) return false;

	CImageIterator iter(this);
	BYTE trans[256];	//for transparency (don't move)
	png_struct *png_ptr;
	png_info *info_ptr;

  cx_try
  {
   /* Create and initialize the png_struct with the desired error handler
    * functions.  If you want to use the default stderr and longjump method,
    * you can supply NULL for the last three parameters.  We also check that
    * the library version is compatible with the one used at compile time,
    * in case we are using dynamically linked libraries.  REQUIRED.
    */
	png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,(void *)NULL,NULL,NULL);
	if (png_ptr == NULL) cx_throw("Failed to create PNG structure");

	/* Allocate/initialize the image information data.  REQUIRED */
	info_ptr = png_create_info_struct(png_ptr);
	if (info_ptr == NULL){
		png_destroy_write_struct(&png_ptr,  (png_infopp)NULL);
		cx_throw("Failed to initialize PNG info structure");
	}

   /* Set error handling.  REQUIRED if you aren't supplying your own
    * error hadnling functions in the png_create_write_struct() call.
    */
	if (setjmp(png_ptr->jmpbuf)){
		/* If we get here, we had a problem reading the file */
		if (info_ptr->palette) free(info_ptr->palette);
		png_destroy_write_struct(&png_ptr,  (png_infopp)&info_ptr);
		cx_throw("Error saving PNG file");
	}
            
	/* set up the output control */
	//png_init_io(png_ptr, hFile);

	// use custom I/O functions
    png_set_write_fn(png_ptr,hFile,/*(png_rw_ptr)*/user_write_data,/*(png_flush_ptr)*/user_flush_data);

	/* set the file information here */
	info_ptr->width = GetWidth();
	info_ptr->height = GetHeight();
	info_ptr->pixel_depth = (BYTE)GetBpp();
	info_ptr->channels = (GetBpp()>8) ? (BYTE)3: (BYTE)1;
	info_ptr->bit_depth = (BYTE)(GetBpp()/info_ptr->channels);
	info_ptr->compression_type = info_ptr->filter_type = 0;
	info_ptr->valid = 0;

	switch(GetCodecOption(CXIMAGE_FORMAT_PNG)){
	case 1:
		info_ptr->interlace_type = PNG_INTERLACE_ADAM7;
		break;
	default:
		info_ptr->interlace_type = PNG_INTERLACE_NONE;
	}

	/* set compression level */
	//png_set_compression_level(png_ptr, Z_BEST_COMPRESSION);

	bool bGrayScale = IsGrayScale();

	if (GetNumColors()){
		if (bGrayScale){
			info_ptr->color_type = PNG_COLOR_TYPE_GRAY;
		} else {
			info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
		}
	} else {
		info_ptr->color_type = PNG_COLOR_TYPE_RGB;
	}
#if CXIMAGE_SUPPORT_ALPHA
	if (AlphaIsValid()){
		info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
		info_ptr->channels++;
		info_ptr->bit_depth = 8;
		info_ptr->pixel_depth += 8;
	}
#endif

	/* set background */
	png_color_16 image_background={ 0, 255, 255, 255, 0 };
	RGBQUAD tc = GetTransColor();
	if (info.nBkgndIndex>=0) {
		image_background.blue  = tc.rgbBlue;
		image_background.green = tc.rgbGreen;
		image_background.red   = tc.rgbRed;
	}
	png_set_bKGD(png_ptr, info_ptr, &image_background);

	/* set metrics */
	png_set_pHYs(png_ptr, info_ptr, head.biXPelsPerMeter, head.biYPelsPerMeter, PNG_RESOLUTION_METER);

	png_set_IHDR(png_ptr, info_ptr, info_ptr->width, info_ptr->height, info_ptr->bit_depth,
				info_ptr->color_type, info_ptr->interlace_type,
				PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);

	//<DP> simple transparency
	if (info.nBkgndIndex >= 0){
		info_ptr->num_trans = 1;
		info_ptr->valid |= PNG_INFO_tRNS;
		info_ptr->trans = trans;
		info_ptr->trans_values.index = (BYTE)info.nBkgndIndex;
		info_ptr->trans_values.red   = tc.rgbRed;
		info_ptr->trans_values.green = tc.rgbGreen;
		info_ptr->trans_values.blue  = tc.rgbBlue;
		info_ptr->trans_values.gray  = info_ptr->trans_values.index;

		// the transparency indexes start from 0 for non grayscale palette
		if (!bGrayScale && head.biClrUsed && info.nBkgndIndex)
			SwapIndex(0,(BYTE)info.nBkgndIndex);
	}

	/* set the palette if there is one */
	if (GetPalette()){
		if (!bGrayScale){
			info_ptr->valid |= PNG_INFO_PLTE;
		}

		int nc = GetClrImportant();
		if (nc==0) nc = GetNumColors();

		if (info.bAlphaPaletteEnabled){
			for(WORD ip=0; ip<nc;ip++)
				trans[ip]=GetPaletteColor((BYTE)ip).rgbReserved;
			info_ptr->num_trans = (WORD)nc;
			info_ptr->valid |= PNG_INFO_tRNS;
			info_ptr->trans = trans;
		}

		// copy the palette colors
		info_ptr->palette = new png_color[nc];
		info_ptr->num_palette = (png_uint_16) nc;
		for (int i=0; i<nc; i++)
			GetPaletteColor(i, &info_ptr->palette[i].red, &info_ptr->palette[i].green, &info_ptr->palette[i].blue);
	}  

#if CXIMAGE_SUPPORT_ALPHA	// <vho>
	//Merge the transparent color with the alpha channel
	if (AlphaIsValid() && head.biBitCount==24 && info.nBkgndIndex>=0){
		for(long y=0; y < head.biHeight; y++){
			for(long x=0; x < head.biWidth ; x++){
				RGBQUAD c=GetPixelColor(x,y,false);
				if (*(long*)&c==*(long*)&tc)
					AlphaSet(x,y,0);
	}	}	}
#endif // CXIMAGE_SUPPORT_ALPHA	// <vho>

	int row_size = max(info.dwEffWidth, info_ptr->width*info_ptr->channels*(info_ptr->bit_depth/8));
	info_ptr->rowbytes = row_size;
	BYTE *row_pointers = new BYTE[row_size];

	/* write the file information */
	png_write_info(png_ptr, info_ptr);

	//interlace handling
	int num_pass = png_set_interlace_handling(png_ptr);
	for (int pass = 0; pass < num_pass; pass++){
		//write image
		iter.Upset();
		long ay=head.biHeight-1;
		RGBQUAD c;
		do	{
#if CXIMAGE_SUPPORT_ALPHA	// <vho>
			if (AlphaIsValid()){
				for (long ax=head.biWidth-1; ax>=0;ax--){
					c = BlindGetPixelColor(ax,ay);
					int px = ax * info_ptr->channels;
					if (!bGrayScale){
						row_pointers[px++]=c.rgbRed;
						row_pointers[px++]=c.rgbGreen;
					}
					row_pointers[px++]=c.rgbBlue;
					row_pointers[px] = AlphaGet(ax,ay);
				}
				png_write_row(png_ptr, row_pointers);
				ay--;
			}
			else
#endif //CXIMAGE_SUPPORT_ALPHA	// <vho>
			{
				iter.GetRow(row_pointers, row_size);
				if (info_ptr->color_type == PNG_COLOR_TYPE_RGB) //HACK BY OP
					RGBtoBGR(row_pointers, row_size);
				png_write_row(png_ptr, row_pointers);
			}
		} while(iter.PrevRow());
	}

	delete [] row_pointers;

	//if necessary, restore the original palette
	if (!bGrayScale && head.biClrUsed && info.nBkgndIndex>0)
		SwapIndex((BYTE)info.nBkgndIndex,0);

	/* It is REQUIRED to call this to finish writing the rest of the file */
	png_write_end(png_ptr, info_ptr);

	/* if you malloced the palette, free it here */
	if (info_ptr->palette){
		delete [] (info_ptr->palette);
		info_ptr->palette = NULL;
	}

	/* clean up after the write, and free any memory allocated */
	png_destroy_write_struct(&png_ptr, (png_infopp)&info_ptr);

  } cx_catch {
	if (strcmp(message,"")) strncpy(info.szLastError,message,255);
	return FALSE;
  }
	/* that's it */
	return TRUE;
}
////////////////////////////////////////////////////////////////////////////////
#endif // CXIMAGE_SUPPORT_ENCODE
////////////////////////////////////////////////////////////////////////////////
#endif // CXIMAGE_SUPPORT_PNG