〔总结〕H5常见效果整理汇总资料

1.Canvas 实现圆形进度条并显示数字百分比

实现效果

1.首先创建html代码

<canvas id="canvas" width="500" height="500" style="background:#000;"></canvas>

2.创建canvas环境

var canvas = document.getElementById('canvas'),  //获取canvas元素
    context = canvas.getContext('2d'),  //获取画图环境，指明为2d
    centerX = canvas.width/2,   //Canvas中心点x轴坐标
    centerY = canvas.height/2,  //Canvas中心点y轴坐标
    rad = Math.PI*2/100, //将360度分成100份，那么每一份就是rad度
    speed = 0.1; //加载的快慢就靠它了

3.绘制5像素宽的运动外圈

//绘制5像素宽的运动外圈
function blueCircle(n){
    context.save();
    context.strokeStyle = "#fff"; //设置描边样式
    context.lineWidth = 5; //设置线宽
    context.beginPath(); //路径开始
    context.arc(centerX, centerY, 100 , -Math.PI/2, -Math.PI/2 +n*rad, false); //用于绘制圆弧context.arc(x坐标，y坐标，半径，起始角度，终止角度，顺时针/逆时针)
    context.stroke(); //绘制
    context.closePath(); //路径结束
    context.restore();
}

4.绘制红色运动圈

function whiteCircle(){
    context.save();
    context.beginPath();
    context.lineWidth = 2; //设置线宽
    context.strokeStyle = "red";
    context.arc(centerX, centerY, 100 , 0, Math.PI*2, false);
    context.stroke();
    context.closePath();
    context.restore();
}

5.百分比文字绘制

function text(n){
    context.save(); //save和restore可以保证样式属性只运用于该段canvas元素
    context.strokeStyle = "#fff"; //设置描边样式
    context.font = "40px Arial"; //设置字体大小和字体
    //绘制字体，并且指定位置
    context.strokeText(n.toFixed(0)+"%", centerX-25, centerY+10);
    context.stroke(); //执行绘制
    context.restore();
}

6.让它运动起来

(function drawFrame(){
    window.requestAnimationFrame(drawFrame);
    context.clearRect(0, 0, canvas.width, canvas.height);
    whiteCircle();
    text(speed);
    blueCircle(speed);
    if(speed > 100) speed = 0;
    speed += 0.1;
}());

完整代码

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>HTML5 Canvas 圆形进度条并显示数字百分比</title>
<style>
    *{margin:0;padding:0;}
    body{text-align:center;background-color:#000;}
</style>
</head>
<body>
<canvas id="canvas" width="500" height="500" style="background:#000;"></canvas>
<script>
    window.onload = function(){
        var canvas = document.getElementById('canvas'),  //获取canvas元素
            context = canvas.getContext('2d'),  //获取画图环境，指明为2d
            centerX = canvas.width/2,   //Canvas中心点x轴坐标
            centerY = canvas.height/2,  //Canvas中心点y轴坐标
            rad = Math.PI*2/100, //将360度分成100份，那么每一份就是rad度
            speed = 0.1; //加载的快慢就靠它了 
            
        //绘制5像素宽的运动外圈
        function blueCircle(n){
            context.save();
            context.strokeStyle = "#fff"; //设置描边样式
            context.lineWidth = 5; //设置线宽
            context.beginPath(); //路径开始
            context.arc(centerX, centerY, 100 , -Math.PI/2, -Math.PI/2 +n*rad, false); //用于绘制圆弧context.arc(x坐标，y坐标，半径，起始角度，终止角度，顺时针/逆时针)
            context.stroke(); //绘制
            context.closePath(); //路径结束
            context.restore();
        }
        //绘制红色运动圈
        function whiteCircle(){
            context.save();
            context.beginPath();
            context.lineWidth = 2; //设置线宽
            context.strokeStyle = "red";
            context.arc(centerX, centerY, 100 , 0, Math.PI*2, false);
            context.stroke();
            context.closePath();
            context.restore();
        }  
        //百分比文字绘制
        function text(n){
            context.save(); //save和restore可以保证样式属性只运用于该段canvas元素
            context.strokeStyle = "#fff"; //设置描边样式
            context.font = "40px Arial"; //设置字体大小和字体
            //绘制字体，并且指定位置
            context.strokeText(n.toFixed(0)+"%", centerX-25, centerY+10);
            context.stroke(); //执行绘制
            context.restore();
        } 
        //动画循环
        (function drawFrame(){
            window.requestAnimationFrame(drawFrame);
            context.clearRect(0, 0, canvas.width, canvas.height);
            whiteCircle();
            text(speed);
            blueCircle(speed);
            if(speed > 100) speed = 0;
            speed += 0.1;
        }());
    }
</script>

</body>
</html>

2.H5实现树叶飘落

实现如图所示的东西效果（落叶下落）：

html代码：

<!DOCTYPE html>
<html>
<head>
    <title>HTML5树叶飘落动画</title>
    <meta charset="utf-8">
    <meta name="viewport" content="width=500px, initial-scale=0.64">
    <link rel="stylesheet" href="leaves.css" type="text/css">
    <script src="leaves.js" type="text/javascript"></script>
</head>
<body>
    <div id="container">
        <div id="leafContainer"></div>
        <div id="message">
            <em>这是基于webkit的落叶动画</em>
        </div>
    </div>  
</body>
</html>

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 > div {
    position: absolute;
    width: 100px;
    height: 100px;
    -webkit-animation-iteration-count: infinite;
    -webkit-animation-direction: normal;
    -webkit-animation-timing-function: linear;
}

#leafContainer > div > 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 < NUMBER_OF_LEAVES; i++) {
        container.appendChild(createALeaf());
    }
}

function randomInteger(low, high){
    return low + Math.floor(Math.random() * (high - low));
}

function randomFloat(low, high){
    return low + Math.random() * (high - low);
}

function pixelValue(value){
    return value + 'px';
}

function durationValue(value){
    return value + 's';
}

function createALeaf(){
    var leafDiv = document.createElement('div');
    leafDiv.style.top = "-100px";
    leafDiv.style.left = pixelValue(randomInteger(0, 500));
    leafDiv.style.webkitAnimationName = 'fade, drop';
    var fadeAndDropDuration = durationValue(randomFloat(5, 11));
    leafDiv.style.webkitAnimationDuration = fadeAndDropDuration + ', ' + fadeAndDropDuration;
    var leafDelay = durationValue(randomFloat(0, 5));
    leafDiv.style.webkitAnimationDelay = leafDelay + ', ' + leafDelay;
    
    var image = document.createElement('img');
    image.src = 'images/realLeaf' + randomInteger(1, 5) + '.png';
    var spinAnimationName = (Math.random() < 0.5) ? 'clockwiseSpin' : 'counterclockwiseSpinAndFlip';
    image.style.webkitAnimationName = spinAnimationName;
    var spinDuration = durationValue(randomFloat(4, 8));
    image.style.webkitAnimationDuration = spinDuration;

    leafDiv.appendChild(image);
    return leafDiv;
}

window.addEventListener('load', init, false);

转载地址：http://www.html5tricks.com/css3-fall-leaves.html

3.canvas处理连续帧图片

html5 canvas处理连续帧图片,下面的代码基于IE8以上

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no"/>
<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('img');
    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='images/ab'+frame+'.png';
        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>
</head>
<body style="position:absolute;margin:0;padding:0;width:100%;height:100%;">
    <canvas id="animation_canvas"></canvas>
</body>
</html>

后续逐渐添加

1.Canvas 实现圆形进度条并显示数字百分比

2.H5实现树叶飘落

3.canvas处理连续帧图片

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