roundRect(x, y, width, height, radii) {
		this.getContext().roundRect(x, y, width, height, radii);
	}
adds a rounded rectangle to the current path.
@param {number} x - The x axis of the coordinate for the rectangle starting point.
@param {number} y - The y axis of the coordinate for the rectangle starting point.
@param {number} width - The rectangle's width.
@param {number} height - The rectangle's height.
@param {number} radius - The corner radius.