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src/Source/FreeImageToolkit/Resize.cpp  view on Meta::CPAN

		FIBITMAP *tmp = NULL;

		if (src_width != dst_width) {
			// source and destination widths are different so, we must
			// filter horizontally
			if (src_height != dst_height) {
				// source and destination heights are also different so, we need
				// a temporary image
				tmp = FreeImage_AllocateT(image_type, dst_width, src_height, dst_bpp_s1, 0, 0, 0);
				if (!tmp) {
					FreeImage_Unload(dst);
					return NULL;
				}
			} else {
				// source and destination heights are equal so, we can directly
				// scale into destination image (second filter method will not
				// be invoked)
				tmp = dst;
			}

			// scale source image horizontally into temporary (or destination) image
			horizontalFilter(src, src_height, src_width, src_offset_x, src_offset_y, src_pal, tmp, dst_width);

			// set x and y offsets to zero for the second filter method
			// invocation (the temporary image only contains the portion of
			// the image to be rescaled with no offsets)
			src_offset_x = 0;
			src_offset_y = 0;

			// also ensure, that the second filter method gets no source
			// palette (the temporary image is palletized only, if it is
			// greyscale; in that case, it is an 8-bit image with a linear
			// palette so, the source palette is not needed or will even be
			// mismatching, if the source palette is unordered)
			src_pal = NULL;
		} else {
			// source and destination widths are equal so, just copy the
			// image pointer
			tmp = src;
		}

		if (src_height != dst_height) {
			// source and destination heights are different so, scale
			// temporary (or source) image vertically into destination image
			verticalFilter(tmp, dst_width, src_height, src_offset_x, src_offset_y, src_pal, dst, dst_height);
		}

		// free temporary image, if not pointing to either src or dst
		if (tmp != src && tmp != dst) {
			FreeImage_Unload(tmp);
		}

	} else {
		// yx filtering
		// -------------

		// Remark:
		// The yx filtering branch could be more optimized by taking into,
		// account that (src_width != dst_width) is always true, which
		// follows from the above condition, which selects filtering order.
		// Since (dst_width <= src_width) == TRUE selects xy filtering,
		// both widths must be different when performing yx filtering.
		// However, to make the code more robust, not depending on that
		// condition and more symmetric to the xy filtering case, these
		// (src_width != dst_width) conditions are still in place.

		FIBITMAP *tmp = NULL;

		if (src_height != dst_height) {
			// source and destination heights are different so, we must
			// filter vertically
			if (src_width != dst_width) {
				// source and destination widths are also different so, we need
				// a temporary image
				tmp = FreeImage_AllocateT(image_type, src_width, dst_height, dst_bpp_s1, 0, 0, 0);
				if (!tmp) {
					FreeImage_Unload(dst);
					return NULL;
				}
			} else {
				// source and destination widths are equal so, we can directly
				// scale into destination image (second filter method will not
				// be invoked)
				tmp = dst;
			}

			// scale source image vertically into temporary (or destination) image
			verticalFilter(src, src_width, src_height, src_offset_x, src_offset_y, src_pal, tmp, dst_height);

			// set x and y offsets to zero for the second filter method
			// invocation (the temporary image only contains the portion of
			// the image to be rescaled with no offsets)
			src_offset_x = 0;
			src_offset_y = 0;

			// also ensure, that the second filter method gets no source
			// palette (the temporary image is palletized only, if it is
			// greyscale; in that case, it is an 8-bit image with a linear
			// palette so, the source palette is not needed or will even be
			// mismatching, if the source palette is unordered)
			src_pal = NULL;

		} else {
			// source and destination heights are equal so, just copy the
			// image pointer
			tmp = src;
		}

		if (src_width != dst_width) {
			// source and destination heights are different so, scale
			// temporary (or source) image horizontally into destination image
			horizontalFilter(tmp, dst_height, src_width, src_offset_x, src_offset_y, src_pal, dst, dst_width);
		}

		// free temporary image, if not pointing to either src or dst
		if (tmp != src && tmp != dst) {
			FreeImage_Unload(tmp);
		}
	}

	return dst;