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Dynamic mechanical watch animation effect drawn by JS+canvas

韦小宝Original: 2018-01-23 11:13:451660browse

This article mainly introduces the dynamic mechanical table animation effect drawn by JS+canvas, involving javascript combined with HTML5 canvas simple numerical calculation and dynamic Drawing related operation skills, friends who are interested in JavaScript can refer to this article

This article describes the dynamic mechanical watch animation effect drawn by JS+canvas. Share it with everyone for your reference, the details are as follows:

Complete example code:

<!DOCTYPE html>
<html>
<head lang="en">
  <meta charset="UTF-8">
  <title>www.php.cn canvas时钟</title>
  <style>
    canvas {
      border: 1px solid red;
    }
  </style>
</head>
<body>
<canvas width="800" height="600"></canvas>
</body>
<script>
  function Clock(opt) {
    for (var key in opt) {
      this[key] = opt[key];
    }
    this.init();
  }
  Clock.prototype = {
    init: function () {
      var self = this;
      var ctx = this.ctx;
      this.timer = setInterval(function(){
        ctx.clearRect(0,0,ctx.canvas.width,ctx.canvas.height);
        self.drawDial();
        self.drawDegreeScale();
        self.drawNumber();
        self.drawPointers();
      },1000);
    },
    drawDial: function () {
      var ctx = this.ctx;
      ctx.save();
      ctx.beginPath();
      ctx.lineWidth = this.clockDialW;
      ctx.strokeStyle = this.clockDialColor;
      ctx.arc(this.clockX, this.clockY, this.clockRadius, 0, 2 * Math.PI);
      ctx.stroke();
      ctx.restore();
    },
    drawDegreeScale: function () {
      var ctx = this.ctx;
      var clockRadius = this.clockRadius;
      var clockX = this.clockX;
      var clockY = this.clockY;
      var bigDegreeScaleL = this.bigDegreeScaleL;
      var smallDegreeScale = this.smallDegreeScale;
      var startX, startY, endX, endY, radian;
      ctx.save();
      for (var i = 0; i < 12; i++) {
        radian = i * Math.PI / 6;
        endX = clockX + clockRadius * Math.cos(radian);
        endY = clockY + clockRadius * Math.sin(radian);
        if (radian % (Math.PI / 2) == 0) {
          startX = clockX + (clockRadius - bigDegreeScaleL) * Math.cos(radian);
          startY = clockY + (clockRadius - bigDegreeScaleL) * Math.sin(radian);
          ctx.lineWidth = this.bigDCWidth;
        } else {
          startX = clockX + (clockRadius - smallDegreeScale) * Math.cos(radian);
          startY = clockY + (clockRadius - smallDegreeScale) * Math.sin(radian);
          ctx.lineWidth = this.smallDCWidth;
        }
        ctx.beginPath();
        ctx.moveTo(startX, startY);
        ctx.lineTo(endX, endY);
        ctx.stroke();
        ctx.restore();
      }
    },
    drawNumber: function () {
      var ctx = this.ctx;
      var textX, textY, textRadian;
      var clockX = this.clockX;
      var clockY = this.clockY;
      var clockRadius = this.clockRadius;
      ctx.font = &#39;20px 微软雅黑&#39;;
      ctx.fillStyle = &#39;red&#39;;
      ctx.textAlign = &#39;center&#39;;
      ctx.textBaseline = &#39;middle&#39;;
      ctx.save();
      for (var i = 0; i < 12; i++) {
        textRadian = i * Math.PI / 6 - Math.PI/3;
        textX = clockX + (clockRadius - 40) * Math.cos(textRadian);
        textY = clockY + (clockRadius - 40) * Math.sin(textRadian);
        ctx.beginPath();
        ctx.fillText(i + 1, textX, textY);
      }
      ctx.restore();
    },
    drawPointers: function () {
      var date = new Date();
      var h = date.getHours();
      var m = date.getMinutes();
      var s = date.getSeconds();
      h = h % 12;
      var hRadian = 2 * Math.PI / 12 * h - Math.PI / 2;
      this.drawPoint(hRadian,30,&#39;red&#39;,8);
      var mRadian = 2 * Math.PI / 60 * m - Math.PI / 2;
      this.drawPoint(mRadian,50,&#39;blue&#39;,6);
      var sRadian = 2 * Math.PI / 60 * s - Math.PI / 2;
      this.drawPoint(sRadian,70,&#39;green&#39;,2);
    },
    drawPoint: function (radian, length,color,lineWidth) {
      var x = this.clockX + Math.cos(radian) * length;
      var y = this.clockY + Math.sin(radian) *　length;
      var ctx = this.ctx;
      ctx.save();
      ctx.beginPath();
      ctx.strokeStyle = color;
      ctx.lineWidth = lineWidth;
      ctx.moveTo(this.clockX,this.clockY);
      ctx.lineTo(x,y);
      ctx.stroke();
      ctx.restore();
    }
  };
</script>
<script>
  var canvas = document.querySelector(&#39;canvas&#39;);
  var ctx = canvas.getContext(&#39;2d&#39;);
  var clock = new Clock({
    ctx: this.ctx,
    clockRadius: 150,
    clockX: 300,
    clockY: 300,
    clockDialW: 6,
    clockDialColor: &#39;blue&#39;,
    bigDegreeScaleL: 20,
    bigDCWidth: 6,
    smallDegreeScale: 10,
    smallDCWidth: 4
  });
</script>
</html>

The above is all the content of this article, I hope it can help everyone learn JavaScript! !

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