pad-app/pages/shipWork/sign.vue

<template>
	<view class="container">

		<view class="sign-box">
			<canvas class="mycanvas" :style="{width:width +'px',height:height +'px'}" canvas-id="mycanvas"
				@touchstart="touchstart" @touchmove="touchmove" @touchend="touchend"></canvas>

			<canvas canvas-id="camCacnvs" :style="{width:height +'px',height:width +'px'}" class="canvsborder"></canvas>

		</view>
		<view class="sigh-btns">
			<van-button class="btn" type="default" @tap="handleCancel">取消</van-button>
			<van-button class="btn" type="default" @tap="handleReset">重写</van-button>
			<van-button class="btn" type="default" @tap="handleConfirm">确认</van-button>
		</view>
	</view>

</template>
<script>
	import utils from '@/common/util.js';
	var x = 20;
	var y = 20;
	var tempPoint = []; //用来存放当前画纸上的轨迹点
	var id = 0;
	var type = '';
	let that;
	let canvasw;
	let canvash;
	export default {
		data() {
			return {
				ctx: '', //绘图图像
				points: [], //路径点集合,
				width: 0,
				height: 0
			};
		},
		mounted() {},
		onLoad(option) {
			that = this;
			console.log(option);
			id = option.id;
			type = option.type;
			this.ctx = uni.createCanvasContext('mycanvas', this); //创建绘图对象
			//设置画笔样式
			this.ctx.lineWidth = 4;
			this.ctx.lineCap = 'round';
			this.ctx.lineJoin = 'round';

			uni.getSystemInfo({
				success: function(res) {
					console.log(res);
					that.width = res.windowWidth * 0.8;
					that.height = res.windowHeight * 0.85;
				}
			});
		},

		methods: {
			//触摸开始，获取到起点
			touchstart: function(e) {
				let startX = e.changedTouches[0].x;
				let startY = e.changedTouches[0].y;
				let startPoint = {
					X: startX,
					Y: startY
				};

				/* **************************************************
				    #由于uni对canvas的实现有所不同，这里需要把起点存起来
				 * **************************************************/
				this.points.push(startPoint);

				//每次触摸开始，开启新的路径
				this.ctx.beginPath();
			},

			//触摸移动，获取到路径点
			touchmove: function(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
				}
				tempPoint.push(movePoint);
			},

			// 触摸结束，将未绘制的点清空防止对后续路径产生干扰
			touchend: function() {
				this.points = [];
			},

			/* ***********************************************	
			#   绘制笔迹
			#   1.为保证笔迹实时显示，必须在移动的同时绘制笔迹
			#   2.为保证笔迹连续，每次从路径集合中区两个点作为起点（moveTo）和终点(lineTo)
			#   3.将上一次的终点作为下一次绘制的起点（即清除第一个点）
			************************************************ */
			draw: function() {
				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);
			},

			handleCancel() {
				uni.navigateBack({
					delta: 1
				});
			},

			//清空画布
			handleReset: function() {
				console.log('handleReset');
				that.ctx.clearRect(0, 0, that.width, that.height);
				that.ctx.draw(true);
				tempPoint = [];
			},

			//将签名笔迹上传到服务器，并将返回来的地址存到本地
			handleConfirm: function() {
				if (tempPoint.length == 0) {
					uni.showToast({
						title: '请先签名',
						icon: 'none',
						duration: 2000
					});
					return;
				}
				uni.canvasToTempFilePath({
					canvasId: 'mycanvas',
					success: function(res) {
						let tempPath = res.tempFilePath;
						console.log(tempPath,'压缩前')
						// 示例用法
						let compressBase64Img = utils.compress(tempPath, 500, 0.3); //conpress封装的压缩方法
						console.log(compressBase64Img,'压缩后');
						const ctx = uni.createCanvasContext('camCacnvs', that);
						ctx.translate(0, that.width);
						ctx.rotate((-90 * Math.PI) / 180);
						ctx.drawImage(tempPath, 0, 0, that.width, that.height);
						ctx.draw();
						setTimeout(() => {

							//保存签名图片到本地
							uni.canvasToTempFilePath({
									canvasId: 'camCacnvs',
									success: function(res) {
										//这是签名图片文件的本地临时地址
										let path = res.tempFilePath;

									},
									fail: err => {
										console.log('fail', err);
									}
								},
								this
							);
						}, 200);
					}
				});
			},
		}
	};
</script>

<style lang="scss" scoped>
	.container {
		height: calc(100vh - 44px);
		padding-bottom: 30px;
		background-color: #fff;
	}

	.sign-box {
		width: 80%;
		height: 90%;
		margin: auto;
		display: flex;
		flex-direction: column;
		text-align: center;
	}

	.sign-view {
		height: 100%;
	}

	.sigh-btns {
		display: flex;
		justify-content: center;
	}

	.btn {
		margin: 30px 10px 0;
	}

	/deep/.van-button {
		width: 100px;
		height: 50px;
		background-color: #fff;
	}

	.mycanvas {
		margin: auto 0rpx;
		background-color: #ececec;
	}

	.canvsborder {
		border: 1rpx solid #333;
		position: fixed;
		top: 0;
		left: 10000rpx;
	}
</style>