使用vue实现一个电子签名组件的示例代码

<canvas
    @touchstart="touchStart"
    @touchmove="touchMove"
    @touchend="touchEnd"
    ref="canvasF"
    @mousedown="mouseDown"
    @mousemove="mouseMove"
    @mouseup="mouseUp"
   ></canvas>

mounted() {
  let canvas = this.$refs.canvasF;
  canvas.height = this.$refs.canvasHW.offsetHeight - 100;
  canvas.width = this.$refs.canvasHW.offsetWidth - 10;
  this.canvasTxt = canvas.getContext("2d");
  this.canvasTxt.strokeStyle = this.color;
  this.canvasTxt.lineWidth = this.linewidth;
 }

//电脑设备事件
  mouseDown(ev) {
   ev = ev || event;
   ev.preventDefault();

   let obj = {
    x: ev.offsetX,
    y: ev.offsetY
   };
   this.startX = obj.x;
   this.startY = obj.y;
   this.canvasTxt.beginPath();//开始作画
   this.points.push(obj);//记录点
   this.isDown = true;
  },

//移动设备事件
  touchStart(ev) {
   ev = ev || event;
   ev.preventDefault();
   if (ev.touches.length == 1) {
    this.isDraw = true; //签名标记
    let obj = {
     x: ev.targetTouches[0].clientX,
     y:
      ev.targetTouches[0].clientY -
      (document.body.offsetHeight * 0.5 +
       this.$refs.canvasHW.offsetHeight * 0.1)
    }; //y的计算值中：document.body.offsetHeight*0.5代表的是除了整个画板signatureBox剩余的高，this.$refs.canvasHW.offsetHeight*0.1是画板中标题的高
    this.startX = obj.x;
    this.startY = obj.y;
    this.canvasTxt.beginPath();//开始作画
    this.points.push(obj);//记录点
   }
  },

//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.moveTo(this.startX, this.startY);//移动画笔
    this.canvasTxt.lineTo(obj.x, obj.y);//创建线条
    this.canvasTxt.stroke();//画线
    this.startY = obj.y;
    this.startX = obj.x;
    this.points.push(obj);//记录点
   }
  },

//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,
     y:
      ev.targetTouches[0].clientY -
      (document.body.offsetHeight * 0.5 +
       this.$refs.canvasHW.offsetHeight * 0.1)
    };
    this.moveY = obj.y;
    this.moveX = obj.x;
    this.canvasTxt.moveTo(this.startX, this.startY);//移动画笔
    this.canvasTxt.lineTo(obj.x, obj.y);//创建线条
    this.canvasTxt.stroke();//画线
    this.startY = obj.y;
    this.startX = obj.x;
    this.points.push(obj);//记录点
   }
  },

//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.closePath();//收笔
    this.points.push(obj);//记录点
    this.points.push({ x: -1, y: -1 });
    this.isDown = false;
   }
  },

//移动设备事件
  touchEnd(ev) {
   ev = ev || event;
   ev.preventDefault();
   if (ev.touches.length == 1) {
    let obj = {
     x: ev.targetTouches[0].clientX,
     y:
      ev.targetTouches[0].clientY -
      (document.body.offsetHeight * 0.5 +
       this.$refs.canvasHW.offsetHeight * 0.1)
    };
    this.canvasTxt.closePath();//收笔
    this.points.push(obj);//记录点
    this.points.push({ x: -1, y: -1 });//记录点
   }
  },

//重写
  overwrite() {
   this.canvasTxt.clearRect(
    0,
    0,
    this.$refs.canvasF.width,
    this.$refs.canvasF.height
   );
   this.points = [];
   this.isDraw = false; //签名标记
  },

data() {
  return {
   points: [],
   canvasTxt: null,
   startX: 0,
   startY: 0,
   moveY: 0,
   moveX: 0,
   endY: 0,
   endX: 0,
   w: null,
   h: null,
   isDown: false,
   color: "#000",
   linewidth: 3,
   isDraw: false //签名标记
  };
 },