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src/Source/FreeImage/PluginPNG.cpp  view on Meta::CPAN

	png_structp png_ptr;
	png_infop info_ptr;
	png_colorp palette = NULL;
	png_uint_32 width, height;
	BOOL has_alpha_channel = FALSE;

	RGBQUAD *pal;					// pointer to dib palette
	int bit_depth, pixel_depth;		// pixel_depth = bit_depth * channels
	int palette_entries;
	int	interlace_type;

	fi_ioStructure fio;
    fio.s_handle = handle;
	fio.s_io = io;

	if ((dib) && (handle)) {
		try {
			// create the chunk manage structure

			png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, (png_voidp)NULL, error_handler, warning_handler);

			if (!png_ptr)  {
				return FALSE;
			}

			// allocate/initialize the image information data.

			info_ptr = png_create_info_struct(png_ptr);

			if (!info_ptr)  {
				png_destroy_write_struct(&png_ptr,  (png_infopp)NULL);
				return FALSE;
			}

			// Set error handling.  REQUIRED if you aren't supplying your own
			// error handling functions in the png_create_write_struct() call.

			if (setjmp(png_jmpbuf(png_ptr)))  {
				// if we get here, we had a problem reading the file

				png_destroy_write_struct(&png_ptr, &info_ptr);

				return FALSE;
			}

			// init the IO
            
			png_set_write_fn(png_ptr, &fio, _WriteProc, _FlushProc);

			// set physical resolution

			png_uint_32 res_x = (png_uint_32)FreeImage_GetDotsPerMeterX(dib);
			png_uint_32 res_y = (png_uint_32)FreeImage_GetDotsPerMeterY(dib);

			if ((res_x > 0) && (res_y > 0))  {
				png_set_pHYs(png_ptr, info_ptr, res_x, res_y, PNG_RESOLUTION_METER);
			}
	
			// Set the image information here.  Width and height are up to 2^31,
			// bit_depth is one of 1, 2, 4, 8, or 16, but valid values also depend on
			// the color_type selected. color_type is one of PNG_COLOR_TYPE_GRAY,
			// PNG_COLOR_TYPE_GRAY_ALPHA, PNG_COLOR_TYPE_PALETTE, PNG_COLOR_TYPE_RGB,
			// or PNG_COLOR_TYPE_RGB_ALPHA.  interlace is either PNG_INTERLACE_NONE or
			// PNG_INTERLACE_ADAM7, and the compression_type and filter_type MUST
			// currently be PNG_COMPRESSION_TYPE_BASE and PNG_FILTER_TYPE_BASE. REQUIRED

			width = FreeImage_GetWidth(dib);
			height = FreeImage_GetHeight(dib);
			pixel_depth = FreeImage_GetBPP(dib);

			BOOL bInterlaced = FALSE;
			if( (flags & PNG_INTERLACED) == PNG_INTERLACED) {
				interlace_type = PNG_INTERLACE_ADAM7;
				bInterlaced = TRUE;
			} else {
				interlace_type = PNG_INTERLACE_NONE;
			}

			// set the ZLIB compression level or default to PNG default compression level (ZLIB level = 6)
			int zlib_level = flags & 0x0F;
			if((zlib_level >= 1) && (zlib_level <= 9)) {
				png_set_compression_level(png_ptr, zlib_level);
			} else if((flags & PNG_Z_NO_COMPRESSION) == PNG_Z_NO_COMPRESSION) {
				png_set_compression_level(png_ptr, Z_NO_COMPRESSION);
			}

			// filtered strategy works better for high color images
			if(pixel_depth >= 16){
				png_set_compression_strategy(png_ptr, Z_FILTERED);
				png_set_filter(png_ptr, 0, PNG_FILTER_NONE|PNG_FILTER_SUB|PNG_FILTER_PAETH);
			} else {
				png_set_compression_strategy(png_ptr, Z_DEFAULT_STRATEGY);
			}

			FREE_IMAGE_TYPE image_type = FreeImage_GetImageType(dib);
			if(image_type == FIT_BITMAP) {
				// standard image type
				bit_depth = (pixel_depth > 8) ? 8 : pixel_depth;
			} else {
				// 16-bit greyscale or 16-bit RGB(A)
				bit_depth = 16;
			}

			// check for transparent images
			BOOL bIsTransparent = 
				(image_type == FIT_BITMAP) && FreeImage_IsTransparent(dib) && (FreeImage_GetTransparencyCount(dib) > 0) ? TRUE : FALSE;

			switch (FreeImage_GetColorType(dib)) {
				case FIC_MINISWHITE:
					if(!bIsTransparent) {
						// Invert monochrome files to have 0 as black and 1 as white (no break here)
						png_set_invert_mono(png_ptr);
					}
					// (fall through)

				case FIC_MINISBLACK:
					if(!bIsTransparent) {
						png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, 
							PNG_COLOR_TYPE_GRAY, interlace_type, 
							PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
						break;