<template> <div> <button @click="generateHeart">生成心形图片</button> <canvas ref="canvas"></canvas> </div> </template> <script> export default { data() { return { canvasWidth: 400, canvasHeight: 400, framesPerSecond: 30, duration: 3000, startTime: null, timer: null, }; }, methods: { generateHeart() { const canvas = this.$refs.canvas; canvas.width = this.canvasWidth; canvas.height = this.canvasHeight; const context = canvas.getContext("2d"); const centerX = canvas.width / 2; const centerY = canvas.height / 2; const stepSize = 0.1; let x = 0; let y = 0; let t = 0; context.beginPath(); context.moveTo(centerX + x, centerY + y); function animateHeart() { if (!this.startTime) { this.startTime = Date.now(); } const elapsed = Date.now() - this.startTime; const progress = elapsed / this.duration; if (progress > 1) { clearInterval(this.timer); this.startTime = null; return; } t += stepSize; x = 16 * Math.pow(Math.sin(t), 3); y = -( 13 * Math.cos(t) - 5 * Math.cos(2 * t) - 2 * Math.cos(3 * t) - Math.cos(4 * t) ); context.lineTo(centerX + x, centerY + y); context.stroke(); } this.timer = setInterval(() => { animateHeart(); }, 1000 / this.framesPerSecond); }, }, }; </script>这段代码有问题吗

这段代码中存在一个问题，即在 `animateHeart` 函数中，`this` 指向的不是组件实例，而是 `window` 对象。因此，需要将 `animateHeart` 函数改为箭头函数，或者使用 `bind` 方法将 `this` 绑定到组件实例上。具体的修改方法如下：

1. 箭头函数：

function animateHeart() {
  if (!this.startTime) {
    this.startTime = Date.now();
  }
  const elapsed = Date.now() - this.startTime;
  const progress = elapsed / this.duration;
  if (progress > 1) {
    clearInterval(this.timer);
    this.startTime = null;
    return;
  }

  t += stepSize;

  x = 16 * Math.pow(Math.sin(t), 3);
  y =
    -(
      13 * Math.cos(t) -
      5 * Math.cos(2 * t) -
      2 * Math.cos(3 * t) -
      Math.cos(4 * t)
    );

  context.lineTo(centerX + x, centerY + y);
  context.stroke();
}

this.timer = setInterval(() => {
  animateHeart();
}, 1000 / this.framesPerSecond);

2. 使用 `bind` 方法：

function animateHeart() {
  if (!this.startTime) {
    this.startTime = Date.now();
  }
  const elapsed = Date.now() - this.startTime;
  const progress = elapsed / this.duration;
  if (progress > 1) {
    clearInterval(this.timer);
    this.startTime = null;
    return;
  }

  t += stepSize;

  x = 16 * Math.pow(Math.sin(t), 3);
  y =
    -(
      13 * Math.cos(t) -
      5 * Math.cos(2 * t) -
      2 * Math.cos(3 * t) -
      Math.cos(4 * t)
    );

  context.lineTo(centerX + x, centerY + y);
  context.stroke();
}

this.timer = setInterval(
  animateHeart.bind(this),
  1000 / this.framesPerSecond
);