基于canvas实现手写签名（vue）

<template>
  <div>
    <canvas id="canvas" width="300" height="150">

    </canvas>
    <div class="btn">
     <span @click="toClear()">清除</span>
     <span @click="toSave()">保存</span>
    </div>
  </div>
</template>

<script>
  export default {
    name: "sign-name",
    data(){
     return {
       ctx:null,
       canvas:null
     }
    },
    mounted() {
     this.initPage()
    },
    methods:{
     initPage() {
      this.canvas = document.getElementById('canvas')
      if(this.canvas.getContext){
       this.ctx = this.canvas.getContext('2d')
       let background = "#ffffff"
       this.ctx.lineCap = 'round'
       this.ctx.fillStyle = background
       this.ctx.lineWidth = 2
       this.ctx.fillRect(0,0,350,150)

       this.canvas.addEventListener("touchstart",(e)=>{
        console.log(123,e)
        this.ctx.beginPath()
        this.ctx.moveTo(e.changedTouches[0].pageX,e.changedTouches[0].pageY)
       })

       this.canvas.addEventListener("touchmove",(e)=>{
        this.ctx.lineTo(e.changedTouches[0].pageX,e.changedTouches[0].pageY)
        this.ctx.stroke()
       })

      }
     },
     toClear() {
      this.ctx.clearRect(0,0,300,150)
     },
     toSave() {
      let base64Img = this.canvas.toDataURL()
      console.log(123,base64Img)
     }
    }

  }
</script>

<style lang="scss" scoped>
 .btn {
  height: px2Vw(55);
  position: fixed;
  bottom: 0;
  line-height: px2Vw(55);
  border-top: px2Vw(1) solid #f7f8f9;
  span {
   display: inline-block;
   width: px2Vw(185);
   text-align: center;
  }
 }
 canvas {
  position: fixed;
  border: 2px dashed #cccccc;
  float: right;
 }
</style>