最近再做移动端电子签名，Vue+Canvas实现，移动端、PC端均可，也可以从github下载。

我在做这个功能的时候参考了 这个代码，但是在移动端光标与实际划线有偏移，我在我的代码中修正了这个问题。

代码

```

JS

export default {

data() {

return {

stageInfo:'',

imgUrl:'',

client: {},

points: [],

canvasTxt: null,

startX: 0,

startY: 0,

moveY: 0,

moveX: 0,

endY: 0,

endX: 0,

w: null,

h: null,

isDown: false,

isViewAutograph: this.$route.query.isViews > 0,

contractSuccess: this.$route.query.contractSuccess

}

},

mounted() {

let canvas = this.$refs.canvasF

canvas.height = this.$refs.canvasHW.offsetHeight - 500

canvas.width = this.$refs.canvasHW.offsetWidth - 50

this.canvasTxt = canvas.getContext('2d')

this.stageInfo = canvas.getBoundingClientRect()

},

methods: {

//mobile

touchStart(ev) {

ev = ev || event

ev.preventDefault()

if (ev.touches.length == 1) {

let obj = {

x: ev.targetTouches[0].clienX,

y: ev.targetTouches[0].clientY,

}

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)

}

},

touchMove(ev) {

ev = ev || event

ev.preventDefault()

if (ev.touches.length == 1) {

let obj = {

x: ev.targetTouches[0].clientX - this.stageInfo.left,

y: ev.targetTouches[0].clientY - this.stageInfo.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)

}

},

touchEnd(ev) {

ev = ev || event

ev.preventDefault()

if (ev.touches.length == 1) {

let obj = {

x: ev.targetTouches[0].clientX - this.stageInfo.left,

y: ev.targetTouches[0].clientY - this.stageInfo.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)

}

},

//pc

mouseDown(ev) {

ev = ev || event

ev.preventDefault()

if (1) {

let obj = {

x: ev.offsetX,

y: ev.offsetY

}

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

}

},

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)

}

},

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

}

},

//重写

overwrite() {

this.canvasTxt.clearRect(0, 0, this.$refs.canvasF.width, this.$refs.canvasF.height)

this.points = []

},

//提交签名

commit() {

this.imgUrl=this.$refs.canvasF.toDataURL();

console.log(this.$refs.canvasF.toDataURL()) //签名img回传后台

}

}

}

CSS

.signatureBox {

width: 100%;

height: calc(100% - 50px);

box-sizing: border-box;

overflow: hidden;

background: #fff;

z-index: 100;

display: flex;

flex-direction: column;

}

.canvasBox {

box-sizing: border-box;

flex: 1;

}

canvas {

border: 1px solid #7d7d7d;

}

.btnBox {

padding: 10px;

text-align: center;

}

.btnBox button:first-of-type {

background: transparent;

border-radius: 4px;

height: 40px;

width: 80px;

font-size: 14px;

}

.btnBox button:last-of-type {

background: #71b900;

color: #fff;

border-radius: 4px;

height: 40px;

width: 80px;

font-size: 14px;

}