如何將自己做的canvas動(dòng)畫特效實(shí)現(xiàn)在自己的桌面背景？

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style>
      body{
        margin: 100px;
      }
      #canvas{
        box-shadow: 0 0  10px #000;
      }
  </style>
</head>
<body>
  <canvas id="canvas">當(dāng)前的瀏覽器不支持該版本</canvas>
</body>
<!-- <script src="./js/underscore.js"></script> -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.3/underscore-min.js"></script>
<script>
    //1.獲取當(dāng)前的畫布
    const canvas = document.getElementById('canvas');
    const ctx = canvas.getContext('2d')//獲取當(dāng)前畫布的上下文，基于2d的
    canvas.width = 800;
    canvas.height = 400;
    canvas.style.backgroundColor = '#000'

    //2.設(shè)置小球這個(gè)類
    class Ball{
      constructor(x,y,color){
          this.x = x;
          this.y = y;
          this.color = color;
          this.r = 20;
      }
     render(){
        ctx.save()//首先開始上下文，并做一個(gè)保存
        ctx.beginPath()//繪制開始的路徑
        ctx.arc(this.x,this.y,this.r,0,Math.PI*2)//繪制一個(gè)小球,參數(shù)為(位置，位置，半徑，起始的角度，結(jié)束的角度)
        ctx.fillStyle=this.color;
        ctx.fill();//繪制小球
        ctx.restore()//和ctx.save()一樣,是通用的格式
      }
    }
    //3.會移動(dòng)的小球類
    class MoveBall extends Ball{ //在這里可以用extends繼承了這個(gè)Ball
        constructor(x,y,color){
          super(x,y,color)//可以通過super來調(diào)用父類的參數(shù)
            //量的變化
            this.dX = _.random(-5,5);
            this.dY = _.random(-5,5);
            this.dR = _.random(1,3);
        }
        upDate(){
          this.x += this.dX;
          this.y += this.dY;
          this.r -= this.dR;
          if(this.r < 0){
            this.r = 0;
          }
        }
    }
  //4.實(shí)例化小球
  let = ballArr = [];
  //5.監(jiān)聽鼠標(biāo)的移動(dòng)
  canvas.addEventListener('mousemove',function(e){
    ballArr.push ( new MoveBall(e.offsetX,e.offsetY,colorArr))
  })
  console.log(ballArr)
  //6.開啟定時(shí)器
  setInterval(function(){
    //清除
    ctx.clearRect(0,0,canvas.width,canvas.height)
      //繪制
      let = colorArr ='#'+(Math.random()*0xffffff<<0).toString(16);//隨機(jī)顏色
      for(let i = 0;i < ballArr.length;i++){
         ballArr[i].render();
         ballArr[i].upDate();
      }
  },30)
</script>
</html>

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