dc_mask = ::CreateCompatibleDC(GetHdcOf(*source));
dc_buffer = ::CreateCompatibleDC(GetHdc());
buffer_bmap = ::CreateCompatibleBitmap(GetHdc(), width, height);
dc_mask = ::CreateCompatibleDC(GetHdcOf(*source));
dc_buffer = ::CreateCompatibleDC(GetHdc());
buffer_bmap = ::CreateCompatibleBitmap(GetHdc(), width, height);