HTML5 and Webkit realize leaf falling animation

What kind of animation will HTML5 and Webkit achieve together? This article will share with you a piece of example code to introduce the implementation of leaf falling animation effect based on HTML5+Webkit. Friends who need it can refer to it. I hope it can help everyone.

Achieve the effect as shown in the picture (falling leaves):

html code:

nbsp;html>


    <title>HTML5树叶飘落动画</title>
    <meta>
    <meta>
    <link>
    <script></script>


    <p>
        </p><p></p>
        <p>
            <em>这是基于webkit的落叶动画</em>
        </p>
      


css代码：
body{
    background-color: #4E4226;
}
#container {
    position: relative;
    height: 700px;
    width: 500px;
    margin: 10px auto;
    overflow: hidden;
    border: 4px solid #5C090A;
    background: #4E4226 url('images/backgroundLeaves.jpg') no-repeat top left;
}
#leafContainer {
    position: absolute;
    width: 100%;
    height: 100%;
}
#message{
    position: absolute;
    top: 160px;
    width: 100%;
    height: 300px;
    background:transparent url('images/textBackground.png') repeat-x center;
    color: #5C090A;
    font-size: 220%;
    font-family: 'Georgia';
    text-align: center;
    padding: 20px 10px;
    -webkit-box-sizing: border-box;
    -webkit-background-size: 100% 100%;
    z-index: 1;
}
em {
    font-weight: bold;
    font-style: normal;
}
#leafContainer > p {
    position: absolute;
    width: 100px;
    height: 100px;
    -webkit-animation-iteration-count: infinite;
    -webkit-animation-direction: normal;
    -webkit-animation-timing-function: linear;
}
#leafContainer > p > img {
     position: absolute;
     width: 100px;
     height: 100px;
     -webkit-animation-iteration-count: infinite;
     -webkit-animation-direction: alternate;
     -webkit-animation-timing-function: ease-in-out;
     -webkit-transform-origin: 50% -100%;
}
@-webkit-keyframes fade{
    0%   { opacity: 1; }
    95%  { opacity: 1; }
    100% { opacity: 0; }
}
@-webkit-keyframes drop{
    0%   { -webkit-transform: translate(0px, -50px); }
    100% { -webkit-transform: translate(0px, 650px); }
}
@-webkit-keyframes clockwiseSpin{
    0%   { -webkit-transform: rotate(-50deg); }
    100% { -webkit-transform: rotate(50deg); }
}
@-webkit-keyframes counterclockwiseSpinAndFlip {
    0%   { -webkit-transform: scale(-1, 1) rotate(50deg); }
    100% { -webkit-transform: scale(-1, 1) rotate(-50deg); }
}
js代码：
const NUMBER_OF_LEAVES = 30;
function init(){
    var container = document.getElementById('leafContainer');
    for (var i = 0; i <p>PS: Let’s take a look at html5 Canvas processes continuous frame images. The following code is based on IE8 and above. </p><pre class="brush:php;toolbar:false">nbsp;html>


<meta>
<meta>
<title>Canvas Demo</title>
<script>
var canvas = null;//初始化参数
var img = null;
var ctx = null;
var imageReady = false;
window.onload = function() {
    var canvas = document.getElementById("animation_canvas");
    canvas.width = canvas.parentNode.clientWidth;
    canvas.height = canvas.parentNode.clientHeight;
    if (!canvas.getContext) {
        console.log("Canvas not supported. Please install a HTML5 compatible browser.");
        return;
    }   
    // get 2D context of canvas and draw rectangel
    ctx = canvas.getContext("2d");
    ctx.fillStyle="black";
    ctx.fillRect(0, 0, canvas.width, canvas.height);
    console.log(canvas.height);
    img = document.createElement(&#39;img&#39;);
    img.src = "images/ab0.png";
    img.onload = loaded();
}  
//保证只有图像加载后才开始循环动画
function loaded() {
    imageReady = true;
    setTimeout( update, 1000/3);//添加3帧每秒间隔计时器
}
function redraw() {
    ctx.fillStyle="black";
    ctx.fillRect(0, 0, 460, 460);
    ctx.drawImage(img, 0, 0, 232, 180);
}   
//为了让图片以规定的速度动画，我们必须追踪已经经过的时间，然后根据分配给每帧的时间播放帧。基本步骤是：
//1、按每秒几帧设置动画速度(msPerFrame)。
//2、当你循环游戏时，计算一下自最后一帧以后已经经过了多少时间（delta）。
//3、如果已经经过的时间足够把动画帧播完，那么播放这一帧并设置累积delta为0。
//4、如果已经经过的时间不够，那么记住（累积）delta时间（acDelta）。
var frame = 0;
var lastUpdateTime = 0;
var acDelta = 0;
var msPerFrame = 200;
function update() {
    requestAnimFrame(update);
    var delta = Date.now() - lastUpdateTime;
    //console.log(Date.now(),lastUpdateTime);
    if (acDelta > msPerFrame){
        acDelta = 0;
        redraw();
        img.src=&#39;images/ab&#39;+frame+&#39;.png&#39;;
        frame++; 
        if(frame >= 3) frame = 0; //当绘制后且帧推进完，计时器就会重置。
    }else{
        acDelta += delta;
    }
    lastUpdateTime = Date.now();
}
//requestAnimFrame的作用基本上就是setTimeout，但浏览器知道你正在渲染帧，所以它可以优化绘制循环，以及如何与剩下的页面回流。
//在某些情况下，setTimeout比requestAnimFrame更好用，特别是对于手机。
//以下是在不同的浏览器上调用requestAnimFrame的情况也不同，标准的检测方法如下：
window.requestAnimFrame = (function(){
    return window.requestAnimationFrame ||
            window.webkitRequestAnimationFrame ||
            window.mozRequestAnimationFrame ||
            window.oRequestAnimationFrame ||
            window.msRequestAnimationFrame ||
            function( callback ){
                window.setTimeout(callback, 1000 / 3); //如果requestAnimFrame支持不可用，还是可以用回内置的setTimeout。
            };
})();
</script>


    <canvas></canvas>

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