https://blog.csdn.net/weixin_45895806/article/details/114635134

<template>
  <div class="signName" :style="{top:0,left:differ+'px'}">
    <div class="close" @click="close"><img src="../assets/images/close.png" alt=""></div>
   <div class="autographBox">
      <div ref="canvasHW">
       <canvas
        @touchstart="touchStart($event)"
        @touchmove="touchMove($event)"
        @touchend="touchEnd($event)"
        ref="canvasF"
      ></canvas>
      </div>
      <p v-if="!isDraw">请本人签名</p>
   </div>
    <div class="autographBtn">
      <div @click="overwrite">重签</div>
      <div @click="seaveImages">确定</div>
    </div>
  </div>
</template>
<script>
import { ref, onMounted } from "vue";
import { Toast } from "vant";
export default {
  name: "index",
  setup(props,cxt) {
    var differ = ref(document.documentElement.clientWidth)
   var canvasF = ref(null);
   var canvasHW = ref(null);
   var canvasTxt = null; //画布
   var points = []; // 记录点
   var isDraw = ref(false); //签名标记
   var startX = 0; //开始坐标x
   var startY = 0;//开始坐标y
   var moveY= 0;
   var moveX= 0;
   var strDataURI ='' // 保存的canvas图像
    onMounted(() =>{
      let canvas =canvasF.value;
      canvas.height = canvasHW.value.offsetHeight - 10;
      canvas.width = canvasHW.value.offsetWidth - 10;
      canvasTxt = canvas.getContext("2d");
      canvasTxt.strokeStyle = '#333';
      canvasTxt.lineWidth = '3';
    }) 
    const touchStart = (ev) => {
      ev = ev || event;
      ev.preventDefault();
      if (ev.touches.length == 1) {
        isDraw.value = true; //签名标记
        let obj = {
          x: ev.targetTouches[0].clientY,
          y: differ.value- ev.targetTouches[0].clientX - (differ.value*0.1)
        }; //y的计算值中：document.body.offsetHeight*0.5代表的是除了整个画板signatureBox剩余的高，this.$refs.canvasHW.offsetHeight*0.1是画板中标题的高
        startX = obj.x;
        startY = obj.y;
        canvasTxt.beginPath();//开始作画
        points.push(obj);//记录点
      }
    }
   const touchMove = (ev)=> {
      ev = ev || event;
      ev.preventDefault();
      if (ev.touches.length == 1) {
        let obj = {
          x: ev.targetTouches[0].clientY,
          y: differ.value- ev.targetTouches[0].clientX - (differ.value*0.1)
        };
        moveY = obj.y;
        moveX = obj.x;
        canvasTxt.moveTo(startX, startY);//移动画笔
        canvasTxt.lineTo(obj.x, obj.y);//创建线条
        canvasTxt.stroke();//画线
        startY = obj.y;
        startX = obj.x;
        points.push(obj);//记录点
      }
    }
    const touchEnd = (ev)=> {
      ev = ev || event;
      ev.preventDefault();
      if (ev.touches.length == 1) {
        let obj = {
          x: ev.targetTouches[0].clientY,
          y: differ.value- ev.targetTouches[0].clientX - (differ.value*0.1)
        };
        points.push(obj);//记录点
        points.push({ x: -1, y: -1 });//记录点
        canvasTxt.closePath();//收笔
        canvasTxt.fill();
      }
    }
    const overwrite = ()=> {
      canvasTxt.clearRect(
        0,
        0,
        canvasF.value.width,
        canvasF.value.height
      );
      points = [];
      isDraw.value = false; //签名标记
    }
  function seaveImages() {
    if(isDraw.value){
       strDataURI = canvasF.value.toDataURL("image/png");
       console.log(strDataURI)
       cxt.emit("autographConfirm", {
        baseCode:strDataURI,
      });
    }else{
      console.log(Toast);
      Toast('您还没有签名')
    }
  }
  function close(){
    cxt.emit("close", {
      closeFlag:false,
    });
  }
    return {
      differ,
      canvasF,
      canvasHW,
      isDraw,
      touchStart,
      touchMove,
      touchEnd,
      overwrite,
      seaveImages,
      close
    };
  },
};
</script>
<style scoped>
.signName{
  position: fixed;
  height: 100vw;
  width: 100vh;
  background-color: #fff;
  transform:rotate(90deg);
  -webkit-transform:rotate(90deg);
  transform-origin: left top;
  z-index: 1000;
  /* top:0;
  left: 0; */
}
.close{
  width: 100%;
  height: 10%;
  padding-left: 2.5rem;
  padding-top: 1.2rem;
}
.close img{
  width: 2rem;
}
 .autographBox{
  width: 100%;
  height: 80%;
  position: relative;
} 
.autographBox div{
  width: 100%;
  height: 100%;
}
.autographBox canvas{
  width: 100%;
  height: 100%;
}
.signName p{
  position: absolute;
  top:50%;
  left: 50%;
  transform: translate(-50%,-50%);
  font-size: 4rem;
  font-weight: bolder;
  color:#436CDF;
  opacity: 0.1;
} 
.autographBtn{
  width: 100%;
  height: 10%;
  display: flex;
  justify-content: center;
  align-items: center;
}
.autographBtn div{
  width: 50%;
  height: 100%;
  color: #fff;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 1.3rem;
}
.autographBtn div:first-child{
  opacity: 0.4;
  background:  -webkit-linear-gradient(top, #728CFD 0%,#5C7EFE 100%);
}
.autographBtn div:last-child{
  background:  -webkit-linear-gradient(top, #728CFD 0%,#5C7EFE 100%);
}
</style>