public static void IndexToCoordinate(this Tileset tileset, long xIndex, long yIndex, out int xCoordinate, out int yCoordinate) { xCoordinate = tileset.Margin + (int)xIndex * (tileset.Tilewidth + tileset.Spacing); yCoordinate = tileset.Margin + (int)yIndex * (tileset.Tileheight + tileset.Spacing); }