【canvas】canvas综合运用：心形图案

news2024/9/24 9:24:22

#简言
利用canvas画出心形图案。

心形

心形图案可以两个椭圆相交组合，也可以直接画路径实现。

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>心形</title>
  <style>
    #canvas {
      border: 1px solid #000;
    }

    #canvas2 {
      border: 1px solid #000;

    }
  </style>
  </style>
</head>

<body>
  <div>
    <canvas id="canvas" width="500" height="500"></canvas>
    <canvas id="canvas2" width="50" height="50"></canvas>

  </div>
  <script>
    const canvas = document.getElementById('canvas');
    const ctx = canvas.getContext('2d');
    let start = [250, 100]
    let end = [250, 400]
    let add = false
    let w = 100
    let redV = 200

    initCanvas2()


    function Drawheart(ctx) {

      if (end[1] > 400) {
        add = false
      } else if (end[1] < 375) {
        add = true
      }
      if (add) {
        end[1] += 1
        start[1] -= 0.2
        w += 2
      } else {
        end[1] -= 1
        start[1] += 0.2
        w -= 2

      }

      let pattern = ctx.createPattern(document.getElementById('canvas2'), 'repeat')
      ctx.clearRect(0, 0, 500, 500);
      ctx.save();
      ctx.strokeStyle = pattern;

      ctx.lineWidth = w;
      // ctx.lineJoin = "round";
      ctx.lineCap = "round";
      ctx.beginPath();
      ctx.moveTo(start[0], start[1])
      ctx.bezierCurveTo(0, 0, 75, 325, end[0], end[1]);
      ctx.moveTo(start[0], start[1])

      ctx.bezierCurveTo(500, 0, 425, 325, end[0], end[1]);

      ctx.shadowColor = "red";
      ctx.shadowOffsetX = 1;
      ctx.shadowOffsetY = 1;

      ctx.shadowBlur = 50;
      ctx.stroke();
      // ctx.fill()
      ctx.restore()
      initCanvas2()
      window.requestAnimationFrame((t) => {
        Drawheart(ctx)
      })
    }
    function initCanvas2() {
      const ctx2 = document.getElementById('canvas2').getContext('2d');
      ctx2.clearRect(0, 0, 50, 50)
      ctx2.save()

      if (add) {
        redV -= 1

        ctx2.rotate(0.05 * Math.PI)

      } else {
        redV += 1
        ctx2.rotate(-0.05 * Math.PI)

      }


      ctx2.beginPath();

      ctx2.moveTo(25, 10)
      ctx2.bezierCurveTo(0, 0, 7.5, 32.5, 25, 40);
      ctx2.moveTo(25, 10)

      ctx2.bezierCurveTo(50, 0, 42.5, 32.5, 25, 40);
      ctx2.fillStyle = `rgba(${redV},0,0,1)`;

      ctx2.shadowColor = "red";
      ctx2.shadowOffsetX = 1;
      ctx2.shadowOffsetY = 1;
      ctx.shadowBlur = 10;

      ctx2.fill();

      ctx2.restore();

    }

    window.requestAnimationFrame(() => Drawheart(ctx))



  </script>
</body>

</html>