uniapp实现微信小程序的电子签名效果(附demo)

<template>
	<view class="page-content">
		<view class="form">
			<view class="form-content">
				<canvas class="form-content__canvas" canvas-id="canvas_sign" @touchstart="touchstart"
					@touchmove="touchmove" @touchend="touchend" disable-scroll="true"></canvas>
			</view>

			<view class="form-footer">
				<button class="form-footer__reset" @click="autographClick(1)">重置</button>
				<button class="form-footer__save" @click="autographClick(2)">保存</button>
				<button class="form-footer__preview" @click="autographClick(3)">预览</button>
			</view>
		</view>

	</view>
</template>


<style lang="scss" scoped>
	/*
	* 横屏后的适配方案
	* @param $rpx为需要转换的字号
	* @参考 https://blog.csdn.net/sdfsfsdscd/article/details/91375066
	**/
	@function tovmin($rpx) {
		@return #{$rpx * 100 / 750}vmin;
	}

	.page-content {
		width: 100vw;
		height: 100vh;

		.form {
			display: flex;
			flex-direction: column;
			width: 100%;
			height: 100%;

			.form-content {
				width: 100%;
				height: 100%;

				&__canvas {
					height: calc(100vh - tovmin(20) - tovmin(120) - constant(safe-area-inset-bottom));
					height: calc(100vh - tovmin(20) - tovmin(120) - env(safe-area-inset-bottom));
					width: 100vw;
				}
			}

			.form-footer {
				padding-top: tovmin(20);
				height: calc(tovmin(120) + constant(safe-area-inset-bottom));
				height: calc(tovmin(120) + env(safe-area-inset-bottom));
				width: 100%;

				display: flex;
				flex-direction: row;

				background: #FFFFFF;
				box-shadow: 0 tovmin(4) tovmin(20) tovmin(2) rgba(183, 183, 183, 0.20);


				button {
					width: 20vw;

					height: tovmin(88);
					line-height: tovmin(88);
					border-radius: tovmin(48);
					text-align: center;
					font-size: tovmin(36);
					font-weight: bold;
				}

				button::after {
					border: none;
				}

				&__reset {
					color: #008AFE;
					border: tovmin(1) solid #008AFE;
				}

				&__save {
					background-image: linear-gradient(135deg, #1BC5FF 0%, #008AFE 100%);
				}

				&__preview {
					color: #008AFE;
					border: tovmin(1) solid #008AFE;
				}
			}
		}
	}
</style>

{
	"pages": [ //pages数组中第一项表示应用启动页，参考：https://uniapp.dcloud.io/collocation/pages
		{
			"path": "pages/index/index",
			"style": {
				"navigationBarTitleText": "亲笔签名",//导航栏标题
				"pageOrientation": "landscape",//切换横屏
				"enablePullDownRefresh": false,//关闭下拉刷新
				"disableScroll": true // 整体页面禁止上下滑动
			}
		}
	],
	"globalStyle": {
		"navigationBarTextStyle": "black",
		"navigationBarBackgroundColor": "#FFFFFF",
		"backgroundColor": "#f5f5f5",
		"navigationStyle": "default", // default/custom。custom即取消默认的原生导航栏
		"mp-alipay": {
			"transparentTitle": "always",
			"titlePenetrate": "YES"
		}
	}
}

		data() {
			return {
				canvasCtx: '', //绘图图像
				points: [], //路径点集合
				hasSign: false,
				isInit: false,
			}
		},
		onLoad(query) {
			this.canvasCtx = uni.createCanvasContext('canvas_sign', this) //创建绘图对象
			//设置画笔样式
			this.canvasCtx.lineWidth = 6
			// 设置线条的端点样式
			this.canvasCtx.lineCap = 'round'
			// 设置线条的交点样式
			this.canvasCtx.lineJoin = 'round'
		},

			touchstart: function(e) {
				if (!this.isInit) {
					this.isInit = true
					this.autographClick(1);
				}
				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.canvasCtx.beginPath()
			},

			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
				}

			},

			touchend: function() {
				this.points = []
				this.canvasCtx.draw(true)
			},

			draw: function() {
				let point1 = this.points[0]
				let point2 = this.points[1]
				this.points.shift()
				this.canvasCtx.moveTo(point1.X, point1.Y)
				this.canvasCtx.lineTo(point2.X, point2.Y)
				this.canvasCtx.stroke()
				this.canvasCtx.draw(true)
				this.hasSign = true
			},

<script>
	export default {
		methods: {
			// 底部按钮点击操作
			autographClick(type) {
				let that = this
				if (type === 1) {
					//清空画布
					this.hasSign = false
					uni.getSystemInfo({
						success: function(res) {
							let canvas = uni.createSelectorQuery().select('.form-content__canvas')
							canvas.boundingClientRect().exec(function(data) {
								console.log('canvas', data)
								console.log('canvas wh:' + data[0].width + 'X' + data[0].height)
								let canvasw = Math.ceil(data[0].width)
								let canvash = Math.ceil(data[0].height)
								that.canvasCtx.fillStyle = '#fff'
								that.canvasCtx.fillRect(0, 0, canvasw, canvash)
								that.canvasCtx.draw(true)
							})
						}
					})

				} else {
					if (!this.hasSign) {
						uni.showToast({
							title: '签名不能为空',
							icon: 'none',
							duration: 2000
						})
						return
					}
					uni.getSystemInfo({
						success: function(res) {
							let canvas = uni.createSelectorQuery().select('.form-content__canvas')
							canvas.boundingClientRect().exec(function(data) {
								console.log('canvas saveSign:', data[0].width + 'X' + data[0].height)
								let canvasw = Math.ceil(data[0].width)
								let canvash = Math.ceil(data[0].height)
								uni.canvasToTempFilePath({
									destWidth: canvasw,
									destHeight: canvash,
									fileType: 'jpg',
									canvasId: 'canvas_sign',
									success: function(res) {
										console.log('图片导出成功：', res)
										let path = res.tempFilePath

										// 保存图片
										if (type === 2) {
											that.uploadPic(path)
										} else if (type === 3) {
											// 预览图片
											uni.previewImage({
												urls: [path]
											})
										}
									},
									fail: (err) => {
										// http://tmp/2LVQyvzddk2R820a9009dff43323d8e7fc9ef7a8d076.jpg
										console.log('图片导出失败：', err)
									}
								})
							})
						}
					})
				}
			},

			// 图片上传处理
			uploadPic(tempFile) {
				// 1、将本地图片上传到服务器（假装是七牛云服务器）
				// 2、将七牛云返回的链接，上传到我们的服务器平台
				console.log("------:", tempFile);
				uni.showLoading({
					title: '正在上传中...'
				})
				setTimeout(() => {
					uni.showToast({
						title: '假装签名上传成功',
						duration: 2000,
						icon: 'none'
					});
				}, 1000);
			}
		}
	}
</script>