日期:2014-05-16  浏览次数:20472 次

转载:JavaScript Tween算法及缓动效果

Flash做动画时会用到Tween类,利用它可以做很多动画效果,例如缓动、弹簧等等。
我这里要教大家的是怎么利用flash的Tween类的算法,来做js的Tween算法,并利用它做一些简单的缓动效果。

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>Tween</title>
</head>
<body>
<div style="padding-left:50px;">
  <div style="position:relative; border:1px solid #000000; width:550px; height:50px;">
    <div id="idMove" style="width:50px; height:50px; background:#930; position:absolute;"></div>
  </div>
  <div style="position:relative;width:550px;height:200px; margin-top:50px;">
    <div id="idChart" style="border:1px solid #000;height:200px;"> </div>
    <div id="idLine" style="position:absolute;top:0;left:0;height:200px;width:1px;background:#000;"></div>
  </div>
</div>
<div>
  <p> Tween类型: <br />
    <label>
      <input name="vTween" type="radio" value="Linear" checked="checked" />
      Linear </label>
    <label>
      <input name="vTween" type="radio" value="Quad" />
      Quadratic </label>
    <label>
      <input name="vTween" type="radio" value="Cubic" />
      Cubic </label>
    <label>
      <input name="vTween" type="radio" value="Quart" />
      Quartic </label>
    <label>
      <input name="vTween" type="radio" value="Quint" />
      Quintic </label>
    <label>
      <input name="vTween" type="radio" value="Sine" />
      Sinusoidal </label>
    <br />
    <label>
      <input name="vTween" type="radio" value="Expo" />
      Exponential </label>
    <label>
      <input name="vTween" type="radio" value="Circ" />
      Circular </label>
    <label>
      <input name="vTween" type="radio" value="Elastic" />
      Elastic </label>
    <label>
      <input name="vTween" type="radio" value="Back" />
      Back </label>
    <label>
      <input name="vTween" type="radio" value="Bounce" />
      Bounce </label>
  </p>
  <p> ease类型: <br />
    <label>
      <input name="vEase" type="radio" value="easeIn" checked="checked" />
      easeIn </label>
    <label>
      <input name="vEase" type="radio" value="easeOut" />
      easeOut </label>
    <label>
      <input name="vEase" type="radio" value="easeInOut" />
      easeInOut </label>
  </p>
  <input id="idSpeed" type="button" value="减慢速度" />
  <input id="idRun" type="button" value=" Run " />
</div>
<script>
/*
算法来源:[url]http://www.robertpenner.com/easing/[/url]
*/
var 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;