ncludes('touch')) { // 处理触摸事件
			var touch = e.touches[0] || e.changedTouches[0];
			newX = touch.clientX - canvas.offsetLeft;
			newY = touch.clientY - canvas.offsetTop;
		} else { // 处理鼠标事件
			newX = e.clientX - canvas.offsetLeft;
			newY = e.clientY - canvas.offsetTop;
		}

		context.beginPath();
		context.moveTo(lastX, lastY);
		context.lineTo(newX, newY);
		context.stroke();
		[lastX, lastY] = [newX, newY];
	}

	// 开始绘制
	function startDrawing(e) {
		isDrawing = true;
		[