<template>
	<view style="padding: 30rpx;">
		<slot name="top"></slot>
		<canvas class="my-canvas-cls" canvas-id="mycanvas" @touchstart="touchstart" @touchmove="touchmove"
			@touchend="touchend"></canvas>
		<slot name="footer"></slot>
		<view class="footer" v-if="footerShow">
			<view class="left" @click="finish">保存</view>
			<view class="right" @click="clear">清除</view>
			<view class="close" @click="close">关闭</view>
		</view>
	</view>
</template>
<script>
	export default {
		data() {
			return {
				//绘图图像
				ctx: '',
				//路径点集合
				points: [],
				//签名图片
				SignatureImg: ''
			};
		},
		props: {
			footerShow:{
				type: Boolean,
				default: true
			}
		},
		watch: {},
		methods: {
			// createCanvas（）----该方法主要是创建了画布
			// touchstart（）----触摸开始，获取到起点
			// touchmove（）----触摸移动，获取到路径点
			// touchend（）----触摸结束，将未绘制的点清空防止对后续路径产生干扰
			// draw（）----绘制笔迹
			// clear（）----清空画布
			// finish（）----完成绘画并保存到本地

			createCanvas() {
				//创建绘图对象
				this.ctx = uni.createCanvasContext('mycanvas', this);
				//设置画笔样式
				this.ctx.lineWidth = 4;
				this.ctx.lineCap = 'round';
				this.ctx.lineJoin = 'round';
			},
			touchstart(e) {
				let startX = e.changedTouches[0].x;
				let startY = e.changedTouches[0].y;
				let startPoint = {
					X: startX,
					Y: startY
				};
				this.points.push(startPoint);
				//每次触摸开始，开启新的路径
				this.ctx.beginPath();
			},
			touchmove(e) {
				let moveX = e.changedTouches[0].x;
				let moveY = e.changedTouches[0].y;
				let movePoint = {
					X: moveX,
					Y: moveY
				};
				this.points.push(movePoint); //存点
				let len = this.points.length;
				if (len >= 2) {
					this.draw(); //绘制路径
				}
			},
			touchend() {
				this.points = [];
			},
			draw() {
				let point1 = this.points[0];
				let point2 = this.points[1];
				this.points.shift();
				this.ctx.moveTo(point1.X, point1.Y);
				this.ctx.lineTo(point2.X, point2.Y);
				this.ctx.stroke();
				this.ctx.draw(true);
			},
			clear() {
				let that = this;
				uni.getSystemInfo({
					success: (res)=> {
						let canvasw = res.windowWidth;
						let canvash = res.windowHeight;
						that.ctx.clearRect(0, 0, canvasw, canvash);
						that.ctx.draw(true);
						this.$emit("clear",res)
					}
				});
			},
			finish() {
				let that = this;
				uni.canvasToTempFilePath({
					canvasId: 'mycanvas',
					success: (res) => {
						//这里的res.tempFilePath就是生成的签字图片
						this.$emit("save", res)
					}
				});
			},
			close(){
				this.$emit("close", res)
			}
		},
		mounted() {
			this.createCanvas();
		}
	};
</script>
<style lang="less" scoped>
	.bigbox {
		touch-action: none
	}

	.my-canvas-cls {
		height: 500rpx;
		width: 100%;
		display: block;
		position: relative;
		background: #F6F6F6;
	}

	.footer {
		font-size: 14px;
		height: 150upx;
		display: flex;
		justify-content: space-around;
		align-items: center;
		padding-left: 40rpx;
		
		.left{
			background-color: #ecf5ff;
			color: #a0cfff;
			border-radius: 8rpx;
			padding: 10rpx 15rpx;
			border: 1px solid #a0cfff;
		}
		.right{
			background-color: #fdf6ec;
			color: #fcbd71;
			border-radius: 8rpx;
			padding: 10rpx 15rpx;
			border: 1px solid #fcbd71;
		}
		.close{
			background-color: #fef0f0;
			color: #fab6b6;
			border-radius: 8rpx;
			padding: 10rpx 15rpx;
			border: 1px solid #fab6b6;
		}
	}

	.but-class {
		margin-right: 40rpx;
	}
</style>