js动画(animate)简单引擎代码示例_Javascript教程-查字典教程网

摘要：用惯了jquery的同学,相信都很欣赏其动画引擎。确实相对比较完善！如果，如果想像力足够丰富的话，相信可以做出超出想像的效果。当然，跟2d库...

用惯了jquery的同学,相信都很欣赏其动画引擎。确实相对比较完善！如果，如果想像力足够丰富的话，相信可以做出超出想像的效果。当然，跟2d库比起来，还是相差相当一段距离。jquery压根也不是专门为动画而设计的。模拟真实世界方面，还是不足的。但在web世界里还是游刃有余的。动画其实一直是flash的专属领地(web区哉)。只是它常常沦为黑客攻击的漏洞所在，而且要装插件，有时候文件实在太大，而且性耗实在是高啊。html5出现后，其实adobe自己都转移阵地到html5了。当然，我觉得很长一段时间内,flash是不会被放弃的。

长话短说，步入正题。仿照flash的动画原理，自己写了一个非常简单的js动画引擎。

首先，用过flash的同学都知道。flash有个时间线，上面布满了“帧”。其实每个帧都是一个镜头，镜头连贯起来就是一副动画效果。其实，这跟电影的原理也一样的，小时候玩过胶片的都知道，对着光可以看到一副副的镜头。人眼分辨两个画面的连贯是有时间限度的。如果想看不到两个画面变换时的闪烁大概30帧/秒左右，电影是24帧的。所以，如果能保证，动画切换能保证每秒30次，基本上，就做到了动画的流畅效果，但是这取决环境。所以具体情况，具体而定，其实关于这方面的知识我也是一知半解。就这个动画引擎而言，了解这么多也差不多足够了，有兴趣可以查找相关知识！

下面开始说说设计原理。

首先需要一个帧频，也就是多少帧每秒。如果有了总用时，就可以计算出整个动画下来有多少个“画面”（总帧数）。这种设计，显然有个不足的地方，不能保证时间正好是个整数帧。除非1ms一帧。这是一个网友提出来的，我感觉不好就没有采用。所以这个引擎是有时间误差的。有了总帧数，当动画运行到最后一帧的时候，整个动画也就播放完。如果需要重复播放，重新把当前帧归0。这种动画有一个好处，就可以直接运行到指定帧。也就是flash里的gotoAndStop和gotoAndPlay。其实整个动画设计原理都是照着flash实现的。包括一个很重要的方法：enterFrame。位置就是根据进入当前帧来计算的。还有其它一些方法：stop、play、next......等等因为目前来说，这个引擎是写非常简单和粗糙的，先不说这么详细了。下面先上代码和示例吧！

animate.js 动画核心

复制代码代码如下:

var animation = function(obj) {

this.obj = obj;

this.frames = 0;

this.timmer = undefined;

this.running = false;

this.ms = [];

}

animation.prototype = {

fps: 36,

init: function(props, duration, tween) {

//console.log('初始化');

this.curframe = 0;

this.initstate = {};

this.props = props;

this.duration = duration || 1000;

this.tween = tween || function(t, b, c, d) {

return t * c / d + b;

};

this.frames = Math.ceil(this.duration * this.fps/1000);

for (var prop in this.props) {

this.initstate[prop] = {

from: parseFloat($util.dom.getStyle(this.obj, prop)),

to: parseFloat(this.props[prop])

};

}

start: function() {

if (!this.running && this.hasNext()) {

//console.log('可以执行...');

this.ms.shift().call(this)

}

return this;

//开始播放

play: function(callback) {

//console.log('开始动画！');

var that = this;

this.running = true;

if (this.timmer) {

this.stop();

}

this.timmer = setInterval(function() {

if (that.complete()) {

that.stop();

that.running = false;

if (callback) {

callback.call(that);

}

return;

}

that.curframe++;

that.enterFrame.call(that);

/ this.fps);

return this;

// 停止动画

stop: function() {

//console.log('结束动画！');

if (this.timmer) {

clearInterval(this.timmer);

// 清除掉timmer id

this.timmer = undefined;

}

go: function(props, duration, tween) {

var that = this;

//console.log(tween)

this.ms.push(function() {

that.init.call(that, props, duration, tween);

that.play.call(that, that.start);

});

return this;

//向后一帧

next: function() {

this.stop();

this.curframe++;

this.curframe = this.curframe > this.frames ? this.frames: this.curframe;

this.enterFrame.call(this);

//向前一帧

prev: function() {

this.stop();

this.curframe--;

this.curframe = this.curframe < 0 ? 0 : this.curframe;

this.enterFrame.call(this);

//跳跃到指定帧并播放

gotoAndPlay: function(frame) {

this.stop();

this.curframe = frame;

this.play.call(this);

//跳到指定帧停止播放

gotoAndStop: function(frame) {

this.stop();

this.curframe = frame;

this.enterFrame.call(this);

//进入帧动作

enterFrame: function() {

//console.log('进入帧：' + this.curframe)

var ds;

for (var prop in this.initstate) {

//console.log('from: ' + this.initstate[prop]['from'])

ds = this.tween(this.curframe, this.initstate[prop]['from'], this.initstate[prop]['to'] - this.initstate[prop]['from'], this.frames).toFixed(2);

//console.log(prop + ':' + ds)

$util.dom.setStyle(this.obj, prop, ds)

}

//动画结束

complete: function() {

return this.curframe >= this.frames;

hasNext: function() {

return this.ms.length > 0;

}

下面是一个简单的工具,其中有所用到的缓动公式：

util.js

复制代码代码如下:

$util = {

/**

* 类型检测

type : function(obj){

var rep = /[objects+(w+)]/i;

var str = Object.prototype.toString.call(obj).toLowerCase();

str.match(rep);

return RegExp.$1;

/**

* 深拷贝

$unlink :function (object){

var unlinked;

switch ($type(object)){

case 'object':

unlinked = {};

for (var p in object) {

unlinked[p] = $unlink(object[p]);

}

break;

case 'array':

unlinked = [];

for (var i = 0, l = object.length; i < l; i++) {

unlinked[i] = $unlink(object[i]);

}

break;

default: return object;

}

return unlinked;

/**

*Dom 相关操作

dom:{

$: function(id) {

return document.getElementById(id);

getStyle: function(obj, prop) {

var style = obj.currentStyle || window.getComputedStyle(obj, '');

if (obj.style.filter) {

return obj.style.filter.match(/d+/g)[0];

}

return style[prop];

setStyle: function(obj, prop, val) {

switch (prop) {

case 'opacity':

if($util.client.browser.ie){

obj.style.filter = 'alpha(' + prop + '=' + val*100 + ')'

}else{

obj.style[prop] = val;

}

break;

default:

obj.style[prop] = val + 'px';

break;

}

setStyles: function(obj, props) {

for (var prop in props) {

switch (prop) {

case 'opacity':

if($util.client.browser.ie){

obj.style.filter = 'alpha(' + prop + '=' + props[prop] + ')'

}else{

obj.style[prop] = props[prop];

}

break;

default:

obj.style[prop] = props[prop] + 'px';

break;

}

/**

*Event 事件相关

evt : {

addEvent : function(oTarget, sEventType, fnHandler) {

if (oTarget.addEventListener) {

oTarget.addEventListener(sEventType, fnHandler, false);

} else if (oTarget.attachEvent) {

oTarget.attachEvent("on" + sEventType, fnHandler);

} else {

oTarget["on" + sEventType] = fnHandler;

}

rmEvent : function removeEventHandler (oTarget, sEventType, fnHandler) {

if (oTarget.removeEventListener) {

oTarget.removeEventListener(sEventType, fnHandler, false);

} else if (oTarget.detachEvent) {

oTarget.detachEvent("on" + sEventType, fnHandler);

} else {

oTarget["on" + sEventType] = null;

}

/**

*Ajax 异步加载

ajax : {

request:function (options) {

var xhr, res;

var url = options.url,

context = options.context,

success = options.success,

type = options.type,

datatype = options.datatype,

async = options.async,

send = options.send,

headers = options.headers;

try {

xhr = new XMLHttpRequest();

} catch(e) {

try {

xhr = new ActiveXObject('MSXML2.XMLHTTP');

} catch(e) {

xhr = new ActiveXObject('Microsoft.XMLHTTP');

}

xhr.onreadystatechange = function() {

if (xhr.readyState == 4 && xhr.status == 200) {

res = xhr.responseText;

success(res);

}

xhr.open(type, url, async);

xhr.send(send);

}

/**

*Array 数组相关

array : {

minIndex : function(ary){

return Math.min.apply(null,ary);

maxitem : function(ary){

return Math.max.apply(null,ary);

}

/**

*Client 客户端检测

client : function(){

// 浏览器渲染引擎 engines

var engine = {

ie: 0,

gecko: 0,

webkit: 0,

khtml: 0,

opera: 0,

//complete version

ver: null

};

// 浏览器

var browser = {

//browsers

ie: 0,

firefox: 0,

safari: 0,

konq: 0,

opera: 0,

chrome: 0,

//specific version

ver: null

};

// 客户端平台platform/device/OS

var system = {

win: false,

mac: false,

x11: false,

//移动设备

iphone: false,

ipod: false,

ipad: false,

ios: false,

android: false,

nokiaN: false,

winMobile: false,

//game systems

wii: false,

ps: false

};

// 检测浏览器引擎

var ua = navigator.userAgent;

if (window.opera){

engine.ver = browser.ver = window.opera.version();

engine.opera = browser.opera = parseFloat(engine.ver);

} else if (/AppleWebKit/(S+)/.test(ua)){

engine.ver = RegExp["$1"];

engine.webkit = parseFloat(engine.ver);

//figure out if it's Chrome or Safari

if (/Chrome/(S+)/.test(ua)){

browser.ver = RegExp["$1"];

browser.chrome = parseFloat(browser.ver);

} else if (/Version/(S+)/.test(ua)){

browser.ver = RegExp["$1"];

browser.safari = parseFloat(browser.ver);

} else {

//approximate version

var safariVersion = 1;

if (engine.webkit < 100){

safariVersion = 1;

} else if (engine.webkit < 312){

safariVersion = 1.2;

} else if (engine.webkit < 412){

safariVersion = 1.3;

} else {

safariVersion = 2;

}

browser.safari = browser.ver = safariVersion;

}

} else if (/KHTML/(S+)/.test(ua) || /Konqueror/([^;]+)/.test(ua)){

engine.ver = browser.ver = RegExp["$1"];

engine.khtml = browser.konq = parseFloat(engine.ver);

} else if (/rv:([^)]+)) Gecko/d{8}/.test(ua)){

engine.ver = RegExp["$1"];

engine.gecko = parseFloat(engine.ver);

//determine if it's Firefox

if (/Firefox/(S+)/.test(ua)){

browser.ver = RegExp["$1"];

browser.firefox = parseFloat(browser.ver);

}

} else if (/MSIE ([^;]+)/.test(ua)){

engine.ver = browser.ver = RegExp["$1"];

engine.ie = browser.ie = parseFloat(engine.ver);

}

//detect browsers

browser.ie = engine.ie;

browser.opera = engine.opera;

//detect platform

var p = navigator.platform;

system.win = p.indexOf("Win") == 0;

system.mac = p.indexOf("Mac") == 0;

system.x11 = (p == "X11") || (p.indexOf("Linux") == 0);

//detect windows operating systems

if (system.win){

if (/Win(?:dows )?([^do]{2})s?(d+.d+)?/.test(ua)){

if (RegExp["$1"] == "NT"){

switch(RegExp["$2"]){

case "5.0":

system.win = "2000";

break;

case "5.1":

system.win = "XP";

break;

case "6.0":

system.win = "Vista";

break;

case "6.1":

system.win = "7";

break;

default:

system.win = "NT";

break;

}

} else if (RegExp["$1"] == "9x"){

system.win = "ME";

} else {

system.win = RegExp["$1"];

}

//mobile devices

system.iphone = ua.indexOf("iPhone") > -1;

system.ipod = ua.indexOf("iPod") > -1;

system.ipad = ua.indexOf("iPad") > -1;

system.nokiaN = ua.indexOf("NokiaN") > -1;

//windows mobile

if (system.win == "CE"){

system.winMobile = system.win;

} else if (system.win == "Ph"){

if(/Windows Phone OS (d+.d+)/.test(ua)){;

system.win = "Phone";

system.winMobile = parseFloat(RegExp["$1"]);

}

//determine iOS version

if (system.mac && ua.indexOf("Mobile") > -1){

if (/CPU (?:iPhone )?OS (d+_d+)/.test(ua)){

system.ios = parseFloat(RegExp.$1.replace("_", "."));

} else {

system.ios = 2; //can't really detect - so guess

}

//determine Android version

if (/Android (d+.d+)/.test(ua)){

system.android = parseFloat(RegExp.$1);

}

//gaming systems

system.wii = ua.indexOf("Wii") > -1;

system.ps = /playstation/i.test(ua);

//return it

return {

engine: engine,

browser: browser,

system: system

};

}(),

/**

*Tween 缓动相关

tween: {

Linear: function(t, b, c, d) {

return c * t / d + b;

Quad: {

easeIn: function(t, b, c, d) {

return c * (t /= d) * t + b;

easeOut: function(t, b, c, d) {

return - c * (t /= d) * (t - 2) + b;

easeInOut: function(t, b, c, d) {

if ((t /= d / 2) < 1) return c / 2 * t * t + b;

return - c / 2 * ((--t) * (t - 2) - 1) + b;

}

Cubic: {

easeIn: function(t, b, c, d) {

return c * (t /= d) * t * t + b;

easeOut: function(t, b, c, d) {

return c * ((t = t / d - 1) * t * t + 1) + b;

easeInOut: function(t, b, c, d) {

if ((t /= d / 2) < 1) return c / 2 * t * t * t + b;

return c / 2 * ((t -= 2) * t * t + 2) + b;

}

Quart: {

easeIn: function(t, b, c, d) {

return c * (t /= d) * t * t * t + b;

easeOut: function(t, b, c, d) {

return - c * ((t = t / d - 1) * t * t * t - 1) + b;

easeInOut: function(t, b, c, d) {

if ((t /= d / 2) < 1) return c / 2 * t * t * t * t + b;

return - c / 2 * ((t -= 2) * t * t * t - 2) + b;

}

Quint: {

easeIn: function(t, b, c, d) {

return c * (t /= d) * t * t * t * t + b;

easeOut: function(t, b, c, d) {

return c * ((t = t / d - 1) * t * t * t * t + 1) + b;

easeInOut: function(t, b, c, d) {

if ((t /= d / 2) < 1) return c / 2 * t * t * t * t * t + b;

return c / 2 * ((t -= 2) * t * t * t * t + 2) + b;

}

Sine: {

easeIn: function(t, b, c, d) {

return - c * Math.cos(t / d * (Math.PI / 2)) + c + b;

easeOut: function(t, b, c, d) {

return c * Math.sin(t / d * (Math.PI / 2)) + b;

easeInOut: function(t, b, c, d) {

return - c / 2 * (Math.cos(Math.PI * t / d) - 1) + b;

}

Expo: {

easeIn: function(t, b, c, d) {

return (t == 0) ? b: c * Math.pow(2, 10 * (t / d - 1)) + b;

easeOut: function(t, b, c, d) {

return (t == d) ? b + c: c * ( - Math.pow(2, -10 * t / d) + 1) + b;

easeInOut: function(t, b, c, d) {

if (t == 0) return b;

if (t == d) return b + c;

if ((t /= d / 2) < 1) return c / 2 * Math.pow(2, 10 * (t - 1)) + b;

return c / 2 * ( - Math.pow(2, -10 * --t) + 2) + b;

}

Circ: {

easeIn: function(t, b, c, d) {

return - c * (Math.sqrt(1 - (t /= d) * t) - 1) + b;

easeOut: function(t, b, c, d) {

return c * Math.sqrt(1 - (t = t / d - 1) * t) + b;

easeInOut: function(t, b, c, d) {

if ((t /= d / 2) < 1) return - c / 2 * (Math.sqrt(1 - t * t) - 1) + b;

return c / 2 * (Math.sqrt(1 - (t -= 2) * t) + 1) + b;

}

Elastic: {

easeIn: function(t, b, c, d, a, p) {

if (t == 0) return b;

if ((t /= d) == 1) return b + c;

if (!p) p = d * .3;

if (!a || a < Math.abs(c)) {

a = c;

var s = p / 4;

} else var s = p / (2 * Math.PI) * Math.asin(c / a);

return - (a * Math.pow(2, 10 * (t -= 1)) * Math.sin((t * d - s) * (2 * Math.PI) / p)) + b;

easeOut: function(t, b, c, d, a, p) {

if (t == 0) return b;

if ((t /= d) == 1) return b + c;

if (!p) p = d * .3;

if (!a || a < Math.abs(c)) {

a = c;

var s = p / 4;

} else var s = p / (2 * Math.PI) * Math.asin(c / a);

return (a * Math.pow(2, -10 * t) * Math.sin((t * d - s) * (2 * Math.PI) / p) + c + b);

easeInOut: function(t, b, c, d, a, p) {

if (t == 0) return b;

if ((t /= d / 2) == 2) return b + c;

if (!p) p = d * (.3 * 1.5);

if (!a || a < Math.abs(c)) {

a = c;

var s = p / 4;

} else var s = p / (2 * Math.PI) * Math.asin(c / a);

if (t < 1) return - .5 * (a * Math.pow(2, 10 * (t -= 1)) * Math.sin((t * d - s) * (2 * Math.PI) / p)) + b;

return a * Math.pow(2, -10 * (t -= 1)) * Math.sin((t * d - s) * (2 * Math.PI) / p) * .5 + c + b;

}

Back: {

easeIn: function(t, b, c, d, s) {

if (s == undefined) s = 1.70158;

return c * (t /= d) * t * ((s + 1) * t - s) + b;

easeOut: function(t, b, c, d, s) {

if (s == undefined) s = 1.70158;

return c * ((t = t / d - 1) * t * ((s + 1) * t + s) + 1) + b;

easeInOut: function(t, b, c, d, s) {

if (s == undefined) s = 1.70158;

if ((t /= d / 2) < 1) return c / 2 * (t * t * (((s *= (1.525)) + 1) * t - s)) + b;

return c / 2 * ((t -= 2) * t * (((s *= (1.525)) + 1) * t + s) + 2) + b;

}

Bounce: {

easeIn: function(t, b, c, d) {

return c - Tween.Bounce.easeOut(d - t, 0, c, d) + b;

easeOut: function(t, b, c, d) {

if ((t /= d) < (1 / 2.75)) {

return c * (7.5625 * t * t) + b;

} else if (t < (2 / 2.75)) {

return c * (7.5625 * (t -= (1.5 / 2.75)) * t + .75) + b;

} else if (t < (2.5 / 2.75)) {

return c * (7.5625 * (t -= (2.25 / 2.75)) * t + .9375) + b;

} else {

return c * (7.5625 * (t -= (2.625 / 2.75)) * t + .984375) + b;

}

easeInOut: function(t, b, c, d) {

if (t < d / 2) return Tween.Bounce.easeIn(t * 2, 0, c, d) * .5 + b;

else return Tween.Bounce.easeOut(t * 2 - d, 0, c, d) * .5 + c * .5 + b;

}

下面是个应用：

复制代码代码如下:

<!DOCTYPE HTML>

<html>

<head>

<title>无标题文档</title>

body{behavior:url("csshover.htc")}

*{padding:0;margin:0}

.mianbox{width:480px;margin:50px auto;height:240px;}

.leftbtn{width:20px;background:#eee;border:1px solid #ddd;float:left;margin-right:8px;height:240px;}

.leftbtn:hover{background:#fff}

.rightbtn{width:20px;background:#eee;border:1px solid #ddd;float:right;height:240px;}

.rightbtn:hover{background:#fff}

.con{width:420px;float:left;height:240px;overflow:hidden;position:relative}

.con ul{ white-space:nowrap;font-size:0;position:absolute;left:0;top:0;}

.con li{display:inline; vertical-align:bottom;margin-right:10px}

</style>

</head>

<body>

<div>

<div>

<ul>

</ul>

</div>

</div>

/**

* @para obj 内容对象

* @para lbtn 左按钮

* @para rbtn 右按钮

* @para w 每次滚动的宽

* @para duration 每次运行时间

* @para tween 缓动类型

function scOnce(obj, lbtn, rbtn, w, autotime, duration,tween){

var am = new animation(_ul),

step=0,

ulen = obj.scrollWidth,

timmerm

dr = 'left',

that = this;

// 最右端?

function isr(){

return parseInt($util.dom.getStyle(obj, 'left')) >=0;

}

// 最左端?

function isl(){

return ulen - Math.abs(parseInt($util.dom.getStyle(obj, 'left')))-10 <= w;

}

if(isr()&&isl())

return;

// 左移

this.goleft = function (){

step += -1*w;

am.go({left:step+"px"},duration,tween).start();

}

// 右移

this.goright = function (){

step += w;

am.go({left:step+"px"},duration,tween).start();

}

// 注册左按钮事件

$util.evt.addEvent(lbtn,'click',function(){

isl()? that.goright():that.goleft();

})

// 注册右按钮事件

$util.evt.addEvent(rbtn,'click',function(){

isr()? that.goleft():that.goright();

})

$util.evt.addEvent(rbtn,'mouseover',function(){

clearTimeout(timmer);

})

$util.evt.addEvent(lbtn,'mouseover',function(){

clearTimeout(timmer);

})

$util.evt.addEvent(rbtn,'mouseout',function(){

timmer = setInterval(auto,autotime);

})

$util.evt.addEvent(lbtn,'mouseout',function(){

timmer = setInterval(auto,autotime);

})

function auto(){

if(isl()){

dr = "right";

}

if(isr()){

dr = "left";

}

that['go'+dr]();

}

timmer = setInterval(auto,autotime);

}

var _ul = document.getElementsByTagName('ul')[0],

lbtn = document.getElementById('leftbtn'),

rbtn = document.getElementById('rightbtn');

var startgo = new scOnce(_ul,lbtn,rbtn,430,3000,500,$util.tween.Quint.easeInOut);

</script>

</body>

</html>