关于canvas:canvas中鼠标点击经过生成小圆点

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<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title></title>
</head>
<body>
  <div id="box" style="width: 500px;height: 500px;margin: 0 auto;">
    <canvas onclick="clcan(event)" id="can" width="500px" height="100px" style="border: 1px solid black;">
    </canvas>
    <canvas id="myCanvas" width="500px" height="100px" style="border: 1px solid black;">
    </canvas>
  </div>
  <script>
    function GetRandomNum(Min, Max) {
      var Range = Max - Min;
      var Rand = Math.random();
      return (Min + Math.round(Rand * Range));
    }
    function mouseCoords(ev) {
      var e = event || window.event;
      var x = e.offsetX || e.layerX;
      var y = e.offsetY || e.layerY;
      return {x, y};
    }
    var globl_w = 500;
    var globl_h = 500;
    makerect(0, 0, globl_w, globl_w);
    // 鼠标点击生成圆
    function clcan(e) {
      var ev = ev || window.event;
      var mousePos = mouseCoords(ev);
      mousePosX = mousePos.x;
      mousePosY = mousePos.y;
      console.log(mousePosX);
      console.log(mousePosY);
      makearc(mousePosX, mousePosY, GetRandomNum(4, 4), 0, 180, 'red');
    }
    function myAnimation() {ctx.clearRect(0, 0, globl_w, globl_h);
    }
    // 生成圆
    function makearc(x, y, r, s, e, color) {var can = document.getElementById('can');
      var ctx = can.getContext("2d");
      ctx.clearRect(0, 0, 500, 500);
      ctx.beginPath();
      ctx.fillStyle = color;
      ctx.arc(x, y, r, s, e);
      ctx.fill();}
    function makerect(x, y, w, h) {var can = document.getElementById('can');
      var ctx = can.getContext("2d");
      ctx.strokeRect(x, y, w, h);
    }
  </script>
  <script>
    const canvas = document.getElementById('myCanvas')
    const ctx = canvas.getContext('2d');
    let ballArr = []

    // 获取随机色彩
    function getRandomColor() {let arr = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 'a', 'b', 'c', 'd', 'e', 'f'];
      let colorArr = []
      for (let i = 0; i < 3; i++) {colorArr.push(arr[parseInt(Math.random() * 16)])
      }
      return `#${colorArr.join('')}`
    }

    // 鼠标挪动时成果
    canvas.addEventListener('mouseover', () => {canvas.addEventListener('mousemove', (e) => {new Ball(e.offsetX, e.offsetY, 15, getRandomColor());
      })
    })

    // 鼠标点击时成果
    canvas.addEventListener('click', (e) => {for (let i = 0; i < 20; i++) {new Ball(e.offsetX, e.offsetY, i, getRandomColor());
      }
    })

    setInterval(() => {ctx.clearRect(0, 0, document.body.clientWidth, document.body.clientHeight)
      ballArr.forEach(item => {item.render();
        item.update()})
    }, 10)


    class Ball {constructor(x, y, r, color) {
        this.x = x;
        this.y = y;
        this.r = r;
        this.dx = Math.random() * 10 - 5
        this.dy = Math.random() * 10 - 5
        this.color = color;
        ballArr.push(this)
      }

      remove() {let index = ballArr.findIndex(item => item === this)
        ballArr.splice(index, 1)
      }

      render() {ctx.beginPath();
        ctx.fillStyle = this.color;
        ctx.arc(this.x, this.y, this.r, 0, 2 * Math.PI);
        ctx.fill();}
      update() {
        this.r -= .1;
        this.x -= this.dx;
        this.y -= this.dy;
        if (this.r <= 0) {this.remove()
          return;
        }
        this.render()}
    }

  </script>
</body>

</html>

正文完