vue+canvas 移動端手寫簽名，合併圖片

<template>
  <div class="sign">
    <div class="header">
        <i class="el-icon-arrow-left backImg" @click="goBack"></i>
        <span class="title">個人簽名</span>
    </div>
    <section class="signature">
        <div class="signatureBox">
            <div class="canvasBox" ref="canvasHW">
                <canvas ref="canvasF" class="canvasStyle" @touchstart='touchStart' @touchmove='touchMove' @touchend='touchEnd' @mousedown="mouseDown" @mousemove="mouseMove" @mouseup="mouseUp"></canvas>
            </div>
        </div>
    </section>
    <div class="btnBox">
        <div @click="overwrite" class="btn1">重置</div>
        <div @click="commit" class="btn1">確定</div>
    </div>
    <div class="imglist-box" :style="imgUrlList.length>0 ? 'border: 1px solid #d9d9d9;' : ''">
      <img v-for="i in imgUrlList" class="imgCanvas" :src="i">
      <img v-show="imgUrlList.length>0" src="../../assets/img/signdelete.png" class="resign" @click="deleteAll">
    </div>
    <div class="tijiao-box">
      <button @click="commitAll" class="tijiao">提 交</button>
    </div>
  </div>
</template>
<script>
import { Bus } from '@/utils'
export default {
  name:'personsign',
  data() {
      return {
        stageInfo:'',
        imgUrl:'',
        imgUrlList:[],
        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 -0
      canvas.width = this.$refs.canvasHW.offsetWidth - 0
      this.canvasTxt = canvas.getContext('2d')
      this.canvasTxt.lineWidth = 4
      this.stageInfo = canvas.getBoundingClientRect()
    },
    methods: {
      goBack(){
        this.$router.go(-1)
        // session.clear()
      },
      //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.strokeRect(20,20,80,100);
          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
        }
      },
      //重寫
      overwrite() {
        this.canvasTxt.clearRect(0, 0, this.$refs.canvasF.width, this.$refs.canvasF.height)
        this.points = []
      },
      //確定簽名
      commit() {
        this.imgUrl=this.$refs.canvasF.toDataURL();
        this.imgUrlList.push(this.imgUrl)
        if(this.imgUrlList.length>0){
          this.canvasTxt.clearRect(0, 0, this.$refs.canvasF.width, this.$refs.canvasF.height)
          this.points = []
        }
      },
      deleteAll(){
        this.imgUrlList = []
      },
      // 提交簽名給前一頁
      commitAll(){
        // 用canvas合併多張圖片的base64爲一張圖的base64
        var canvas = document.createElement("canvas");
        canvas.width = 75*this.imgUrlList.length;
        canvas.height = 100;
        var context = canvas.getContext("2d");

        context.rect(0 , 0 , canvas.width , canvas.height);
        context.fillStyle = "#fff";
        context.fill();

        var myImage = new Image();
        myImage.crossOrigin = 'Anonymous';
        // 當簽名列表有值時
        if(this.imgUrlList.length>0){
          for(let i = 0;i<this.imgUrlList.length;i++){
            myImage.src = this.imgUrlList[i]
            // 多張圖片繪製成一張圖片
            context.drawImage(myImage , 50*i , 0 , 75 , 75); //context.drawImage(img,x,y,width,height);
            // context.font = "60px Courier New";
            // context.fillText("我是文字",350,450);
          }
          var base64 = canvas.toDataURL("image/jpg");  //"image/jpg" 這裏注意一下
          this.$router.go(-1) //要在bus之前寫不然值傳不回去
          setTimeout(() => {
            Bus.$emit('signImage',base64) //簽名base64傳給前一頁
          }, 300)
        }
      }
    },
    beforeDestroy(){
      // 銷燬bus
      Bus.$off()
    }
}
</script>
<style scoped lang="scss">
// 簽名樣式很重要，會影響觸點位置
.sign{
    width: 100%;
    min-height: 100vh;
    position: relative;
    .header{
      margin-bottom: 20px;
    }
    .tijiao-box{
       width: 100%;
       text-align: center;
    }
    .tijiao{
       width: 90%;
        height: 84px;
        color: #fff;
        border-radius: 2px;
        background: #fa4b31;
        box-shadow: 0 0 0px 1px #fa4b31;
        font-size: 30px;

      }
}
.signature{
  width: 100%;
  height: 50vh;
}
.imglist-box{
  width: 90%;
  margin: 0 auto;
  margin-bottom: 20px;
  position: relative;
}
.imgCanvas{
  width: 150px;
  height: 150px;
}
.resign{
  width: 14%;
  position: absolute;
  top: 0;
  right: 0;
}
  .signatureBox {
    width: 90%;
    margin: 0 auto;
    height: calc(100% - 50px);
    box-sizing: border-box;
    overflow: hidden;
    background: #fff;
    z-index: 100;
    display: flex;
    flex-direction: column;
    align-items: center;
  }
  .canvasBox {
    width: 100%;
    align-items: center;
    box-sizing: border-box;
    flex: 1;
  }
  canvas {
    background-image: url('../../assets/img/signbg.png');
    background-position: center center;
    background-repeat: no-repeat;
    background-origin: border-box;
    background-size: 100% 100%;
  }
  .btnBox{
    width: 90%;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    margin-bottom: 20px;
    .btn1{
      width: 46%;
      height: 84px;
      line-height: 84px;
      color: #fa4b31;
      border-radius: 2px;
      background: #fff;
      border: 1px solid #fa4b31;
      box-shadow: 0 0 0px 1px #fa4b31;
      font-size: 30px;
      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;
  }
</style>

重置就是清除田字格當前字，確定就將字保存爲一張圖片base64排列在列表。

重籤就是刪除列表所有圖片，提交就是將多張圖合併爲一張且傳給前一頁顯示。