这段代码是一个HTML5 Canvas动画，它通过JavaScript创建了一个动态的爱心效果。页面初始化时，首先定义了一些基本设置，如粒子数量、持续时间、速度等。然后，定义了Point和Particle类，用于处理粒子的位置和运动。接着，使用ParticlePool管理粒子池，实现粒子的循环利用。
核心动画逻辑在`render`函数中，这个函数会在每一帧调用`requestAnimationFrame`来更新和渲染粒子。动画效果通过在Canvas上绘制粒子来实现，粒子从爱心形状的路径上发射出来，随着时间逐渐消失，形成了一个连续的动态效果。
此外，还有一个`pointOnHeart`函数用于生成爱心形状的路径点，以及一个辅助函数用于创建粒子图像。整个动画在全屏黑色背景上运行。
整体来看，这段代码展示了如何使用HTML5 Canvas和JavaScript来创建复杂的动画效果，适合用于网页装饰或特殊场合的视觉效果展示。
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<style>* {padding: 0;margin: 0;}html,body {height: 100%;padding: 0;margin: 0;background: #000;}canvas {position: absolute;width: 100%;height: 100%;}.aa {position: fixed;/* 固定位置 */left: 50%;/* 向左移动自身宽度的50% */transform: translateX(-50%);/* 向左移动自身宽度的50%，实现水平居中 */top: 45%;color: #ccc;/* 文字颜色设置为灰色 */font-family: Arial, sans-serif;/* 设置字体 */font-size: 30px;/* 设置字体大小 */}
</style><body><canvas id="pinkboard"></canvas><div class="aa">美羊羊</div> <!-- 名字 --><script>/** 设置动画参数*/var settings = {particles: {length: 500, // 粒子的最大数量duration: 2, // 粒子存在的时间（秒）velocity: 100, // 粒子的速度（像素/秒）effect: -0.75, // 控制粒子运动效果的参数size: 30 // 粒子的大小（像素）},};/** RequestAnimationFrame polyfill by Erik M?ller*/(function () { var b = 0; var c = ["ms", "moz", "webkit", "o"]; for (var a = 0; a < c.length && !window.requestAnimationFrame; ++a) { window.requestAnimationFrame = window[c[a] + "RequestAnimationFrame"]; window.cancelAnimationFrame = window[c[a] + "CancelAnimationFrame"] || window[c[a] + "CancelRequestAnimationFrame"] } if (!window.requestAnimationFrame) { window.requestAnimationFrame = function (h, e) { var d = new Date().getTime(); var f = Math.max(0, 16 - (d - b)); var g = window.setTimeout(function () { h(d + f) }, f); b = d + f; return g } } if (!window.cancelAnimationFrame) { window.cancelAnimationFrame = function (d) { clearTimeout(d) } } }());/** 点(Point)类，用于处理二维空间中的点*/var Point = (function () {function Point(x, y) {this.x = (typeof x !== 'undefined') ? x : 0;this.y = (typeof y !== 'undefined') ? y : 0;}Point.prototype.clone = function () {return new Point(this.x, this.y);};Point.prototype.length = function (length) {if (typeof length == 'undefined')return Math.sqrt(this.x * this.x + this.y * this.y);this.normalize();this.x *= length;this.y *= length;return this;};Point.prototype.normalize = function () {var length = this.length();this.x /= length;this.y /= length;return this;};return Point;})();/** 粒子(Particle)类，用于创建和管理动画中的粒子*/var Particle = (function () {function Particle() {this.position = new Point();this.velocity = new Point();this.acceleration = new Point();this.age = 0;}Particle.prototype.initialize = function (x, y, dx, dy) {this.position.x = x;this.position.y = y;this.velocity.x = dx;this.velocity.y = dy;this.acceleration.x = dx * settings.particles.effect;this.acceleration.y = dy * settings.particles.effect;this.age = 0;};Particle.prototype.update = function (deltaTime) {this.position.x += this.velocity.x * deltaTime;this.position.y += this.velocity.y * deltaTime;this.velocity.x += this.acceleration.x * deltaTime;this.velocity.y += this.acceleration.y * deltaTime;this.age += deltaTime;};Particle.prototype.draw = function (context, image) {function ease(t) {return (--t) * t * t + 1;}var size = image.width * ease(this.age / settings.particles.duration);context.globalAlpha = 1 - this.age / settings.particles.duration;context.drawImage(image, this.position.x - size / 2, this.position.y - size / 2, size, size);};return Particle;})();/** 粒子池(ParticlePool)类，用于高效管理大量粒子*/var ParticlePool = (function () {var particles,firstActive = 0,firstFree = 0,duration = settings.particles.duration;function ParticlePool(length) {// create and populate particle poolparticles = new Array(length);for (var i = 0; i < particles.length; i++)particles[i] = new Particle();}ParticlePool.prototype.add = function (x, y, dx, dy) {particles[firstFree].initialize(x, y, dx, dy);// handle circular queuefirstFree++;if (firstFree == particles.length) firstFree = 0;if (firstActive == firstFree) firstActive++;if (firstActive == particles.length) firstActive = 0;};ParticlePool.prototype.update = function (deltaTime) {var i;// update active particlesif (firstActive < firstFree) {for (i = firstActive; i < firstFree; i++)particles[i].update(deltaTime);}if (firstFree < firstActive) {for (i = firstActive; i < particles.length; i++)particles[i].update(deltaTime);for (i = 0; i < firstFree; i++)particles[i].update(deltaTime);}// remove inactive particleswhile (particles[firstActive].age >= duration && firstActive != firstFree) {firstActive++;if (firstActive == particles.length) firstActive = 0;}};ParticlePool.prototype.draw = function (context, image) {// draw active particlesif (firstActive < firstFree) {for (i = firstActive; i < firstFree; i++)particles[i].draw(context, image);}if (firstFree < firstActive) {for (i = firstActive; i < particles.length; i++)particles[i].draw(context, image);for (i = 0; i < firstFree; i++)particles[i].draw(context, image);}};return ParticlePool;})();/** 动画的主要逻辑*/(function (canvas) {var context = canvas.getContext('2d'),particles = new ParticlePool(settings.particles.length),particleRate = settings.particles.length / settings.particles.duration, // particles/sectime;// 根据给定的参数t，计算爱心形状上的点function pointOnHeart(t) {return new Point(160 * Math.pow(Math.sin(t), 3),130 * Math.cos(t) - 50 * Math.cos(2 * t) - 20 * Math.cos(3 * t) - 10 * Math.cos(4 * t) + 25);}// 创建粒子图像，用于在动画中显示var image = (function () {var canvas = document.createElement('canvas'),context = canvas.getContext('2d');canvas.width = settings.particles.size;canvas.height = settings.particles.size;// helper function to create the pathfunction to(t) {var point = pointOnHeart(t);point.x = settings.particles.size / 2 + point.x * settings.particles.size / 350;point.y = settings.particles.size / 2 - point.y * settings.particles.size / 350;return point;}// create the pathcontext.beginPath();var t = -Math.PI;var point = to(t);context.moveTo(point.x, point.y);while (t < Math.PI) {t += 0.01; // baby steps!point = to(t);context.lineTo(point.x, point.y);}context.closePath();// create the fillcontext.fillStyle = '#ea80b0';context.fill();// create the imagevar image = new Image();image.src = canvas.toDataURL();return image;})();// 渲染函数，用于每一帧的动画绘制function render() {// next animation framerequestAnimationFrame(render);// update timevar newTime = new Date().getTime() / 1000,deltaTime = newTime - (time || newTime);time = newTime;// clear canvascontext.clearRect(0, 0, canvas.width, canvas.height);// create new particlesvar amount = particleRate * deltaTime;for (var i = 0; i < amount; i++) {var pos = pointOnHeart(Math.PI - 2 * Math.PI * Math.random());var dir = pos.clone().length(settings.particles.velocity);particles.add(canvas.width / 2 + pos.x, canvas.height / 2 - pos.y, dir.x, -dir.y);}// update and draw particlesparticles.update(deltaTime);particles.draw(context, image);}// 处理Canvas大小变化的函数function onResize() {canvas.width = canvas.clientWidth;canvas.height = canvas.clientHeight;}window.onresize = onResize;// 延迟启动渲染，确保页面元素加载完毕setTimeout(function () {onResize();render();}, 10);})(document.getElementById('pinkboard'));</script>
</body></html>效果图：
![[vue] pdf.js / vue-pdf 文件花屏问题](https://i-blog.csdnimg.cn/direct/9ee4cec22138473a88801c212fce7e4d.png)
