最近公司要求用h5实现电子签名，在网上搜索后，发现一章文章很实用，用vue，canvas实现。在移动端上需要在获取当前页面的绝对位置。才不会导致touch事件的偏移。代码如下：
<!--html-->
<template>
<div class="signatureBox">
<div class="visaDetailTop">
<p>
<button class="btnBack" @click="backHome"></button>
<img
src="static/imagesWbe/leftIcon.png"
style="height: 1.2em;margin-top: 0.2em;"
@click="backHome"
>
</p>
<p>
<img src="static/imagesWbe/daohanga.png" style="height: 1.2em;margin-top: 0.2em;">
<img
src="static/imagesWbe/shareB.png"
style="height: 1.2em;margin-top: 0.2em;margin-left: 0.2em;"
>
</p>
<p class="visaTitle">电子签名</p>
</div>
<div class="canvasBox" ref="canvasHW">
<canvas
@touchstart="touchStart"
@touchmove="touchMove"
@touchend="touchEnd"
ref="canvasF"
@mousedown="mouseDown"
@mousemove="mouseMove"
@mouseup="mouseUp"
></canvas>
<div class="btnBox">
<button @click="overwrite">重写</button>
<button>提交签名</button>
</div>
</div>
</div>
</template>
<script>
//js
import axios from "axios";
export default {
name: "signature",
data() {
return {
points: [],
canvasTxt: null,
stage_info: [],
startX: 0,
startY: 0,
moveY: 0,
moveX: 0,
endY: 0,
endX: 0,
w: null,
h: null,
isDown: false
};
},
created() {},
mounted() {
let canvas = this.$refs.canvasF;
canvas.height = this.$refs.canvasHW.offsetHeight - 60;
canvas.width = this.$refs.canvasHW.offsetWidth - 10;
this.canvasTxt = canvas.getContext("2d");
this.stage_info = canvas.getBoundingClientRect();
},
components: {
NavPublic
},
methods: {
backHome() {
window.history.back();
},
//电脑设备事件
mouseDown(ev) {
ev = ev || event;
ev.preventDefault();
console.log(ev);
if (ev) {
let obj = {
x: ev.offsetX,
y: ev.offsetY
};
console.log(obj);
this.startX = obj.x;
this.startY = obj.y;
this.canvasTxt.beginPath();
this.canvasTxt.moveTo(this.startX, this.startY);
this.canvasTxt.lineTo(obj.x, obj.y);
this.canvasTxt.stroke();
this.canvasTxt.closePath();
this.points.push(obj);
this.isDown = true;
}
}, //移动设备事件
touchStart(ev) {
ev = ev || event;
ev.preventDefault();
if (ev.touches.length == 1) {
let obj = {
x: ev.targetTouches[0].clientX - this.stage_info.left,
y: ev.targetTouches[0].clientY - this.stage_info.top
};
this.startX = obj.x;
this.startY = obj.y;
this.canvasTxt.beginPath();
this.canvasTxt.moveTo(this.startX, this.startY);
this.canvasTxt.lineTo(obj.x, obj.y);
this.canvasTxt.stroke();
this.canvasTxt.closePath();
this.points.push(obj);
}
},
//电脑设备事件
mouseMove(ev) {
ev = ev || event;
ev.preventDefault();
if (this.isDown) {
let obj = {
x: ev.offsetX,
y: ev.offsetY
};
this.moveY = obj.y;
this.moveX = obj.x;
this.canvasTxt.beginPath();
this.canvasTxt.moveTo(this.startX, this.startY);
this.canvasTxt.lineTo(obj.x, obj.y);
this.canvasTxt.stroke();
this.canvasTxt.closePath();
this.startY = obj.y;
this.startX = obj.x;
this.points.push(obj);
}
}, //移动设备事件
touchMove(ev) {
ev = ev || event;
ev.preventDefault();
if (ev.touches.length == 1) {
let obj = {
x: ev.targetTouches[0].clientX - this.stage_info.left,
y: ev.targetTouches[0].clientY - this.stage_info.top
};
this.moveY = obj.y;
this.moveX = obj.x;
this.canvasTxt.beginPath();
this.canvasTxt.moveTo(this.startX, this.startY);
this.canvasTxt.lineTo(obj.x, obj.y);
this.canvasTxt.stroke();
this.canvasTxt.closePath();
this.startY = obj.y;
this.startX = obj.x;
this.points.push(obj);
}
}, //电脑设备事件
mouseUp(ev) {
ev = ev || event;
ev.preventDefault();
if (1) {
let obj = {
x: ev.offsetX,
y: ev.offsetY
};
this.canvasTxt.beginPath();
this.canvasTxt.moveTo(this.startX, this.startY);
this.canvasTxt.lineTo(obj.x, obj.y);
this.canvasTxt.stroke();
this.canvasTxt.closePath();
this.points.push(obj);
this.points.push({ x: -1, y: -1 });
this.isDown = false;
}
}, //移动设备事件
touchEnd(ev) {
ev = ev || event;
ev.preventDefault();
console.log(ev);
if (ev.touches.length == 1) {
let obj = {
x: ev.targetTouches[0].clientX - this.stage_info.left,
y: ev.targetTouches[0].clientY - this.stage_info.top
};
this.canvasTxt.beginPath();
this.canvasTxt.moveTo(this.startX, this.startY);
this.canvasTxt.lineTo(obj.x, obj.y);
this.canvasTxt.stroke();
this.canvasTxt.closePath();
this.points.push(obj);
this.points.push({ x: -1, y: -1 });
}
}, //重写
overwrite() {
this.canvasTxt.clearRect(
0,
0,
this.$refs.canvasF.width,
this.$refs.canvasF.height
);
this.points = [];
}
}
};
</script>
<style scoped>
//css
.signatureBox{
position: absolute;
top: 0px;
left: 0px;
width: 100%;
height: 100%;
box-sizing: border-box;
overflow: hidden;
background: #fff;
z-index: 100;
display: flex;
flex-direction: column;
}
.visaDetailTop{
/*position: absolute;*/ /*top: 0px;*/ /*left: 0px;*/
width: 100%;
/*overflow: hidden;*/
padding: 5px;
box-sizing: border-box;
z-index: 2;
border-bottom: 1px solid #e5e5e5;
}
.visaDetailTop p{
margin: 0px;
text-align: center;
color: #000;
font-size: 1em;
position: relative;
}
p.visaTitle{
width: 100%;
position: absolute;
top: 5px;
left: 0px;
text-align: center;
font-size: 1.2em;
}
.btnBack{
display: block;
position: absolute;
top: 0px;
left: 0px;
width: 100%;
height: 100%;
z-index: 1;
background: transparent;
border-color: transparent;
outline: none;
}
.btnDaoHang{
display: block;
position: absolute;
left: 0px;
top: 0px;
height: 2.2em;
width: 2em;
z-index: 1;
background: transparent;
border-color: transparent;
outline: none;
}
.visaDetailTop p span{
color: #fff;
font-size: 1.2em;
}
.visaDetailTop p:first-of-type{
float: left;
}
.visaDetailTop p:nth-of-type(2){
float: right;
}
.canvasBox{
padding: 10px 5px;
box-sizing: border-box;
flex: 1;
}
canvas{
border: 1px solid #71b900;
}
.btnBox{
height: 30px;
padding: 5px;
text-align: right;
line-height: 30px;
}
.btnBox button:first-of-type{
border: 1px solid #71b900;
background: transparent;
border-radius: 4px;
padding: 5px 10px;
}
.btnBox button:last-of-type{
border: 1px solid #71b900;
background: #71b900;
color: #fff;
border-radius: 4px;
padding: 5px 10px;
}
@media only screen and (min-width: 750px){
.signatureBox{
position: absolute;
top: 0px;
left: 0px;
width: 100%;
min-height: 100%;
box-sizing: border-box;
overflow: visible;
}
}
</style>
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