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javascript的緩動(dòng)效果（第2部分）

這部分對(duì)原先的緩動(dòng)函數(shù)進(jìn)行抽象化，并結(jié)合緩動(dòng)公式進(jìn)行強(qiáng)化。成品的效果非常驚人逆天。走過(guò)路過(guò)不要錯(cuò)過(guò)。

好了，打諢到此為止。普通的加速減速是難以讓人滿意的，為了實(shí)現(xiàn)彈簧等讓人眼花繚亂的效果必須動(dòng)用緩動(dòng)公式。我見過(guò)兩套緩動(dòng)公式，一套是早期Robert Penner大神的緩動(dòng)公式，內(nèi)置到tween類中，不過(guò)現(xiàn)在人們?cè)絹?lái)越推薦tweenlite這個(gè)新秀了。另一套是script.aculo.us與mootools里面的，由于mootools可稱之為prototype的升級(jí)版，script.aculo.us則是基于prototype，我們就把它們并稱為prototype流派。與flash流派最大的不同是，它們封裝得更好，并只需傳入一個(gè)參數(shù)（0~1的小數(shù)），并且擁有嚴(yán)密的隊(duì)列機(jī)制來(lái)調(diào)用各種回調(diào)函數(shù)。如在回調(diào)函數(shù)設(shè)置元素的長(zhǎng)寬，就弄成Scale特效，利用它我們進(jìn)一步制作SlideUp，SlideDown，Squish等復(fù)合特效。

我們先來(lái)看flash流派的緩動(dòng)公式，它們基本都有如下四個(gè)參數(shù)。

t:timestamp，指緩動(dòng)效果開始執(zhí)行到當(dāng)前幀開始執(zhí)行時(shí)經(jīng)過(guò)的時(shí)間段，單位ms
b:beginning position，起始位置
c:change，要移動(dòng)的距離，就是終點(diǎn)位置減去起始位置。
d: duration ，緩和效果持續(xù)的時(shí)間。

我們把這四個(gè)參數(shù)傳入Robert Penner大神的緩動(dòng)公式，它就會(huì)計(jì)算出當(dāng)前幀物體移動(dòng)的位置。我們對(duì)比原來(lái)的函數(shù)來(lái)改寫。

  var transition = function(el){
    transition.linear = function(t,b,c,d){ return c*t/d + b; };//免費(fèi)提供一個(gè)緩動(dòng)公式（勻速運(yùn)動(dòng)公式）
    el.style.position = "absolute";
    var options = arguments[1] || {},
    begin =  getCoords(el).left,//開始位置
    change = parseFloat(getStyle(_("taxiway"),"width")) - parseFloat(getStyle(el,"width")),//要移動(dòng)的距離
    duration = options.duration || 500,//緩動(dòng)效果持續(xù)時(shí)間
    ease = options.ease || transition.linear,//要使用的緩動(dòng)公式
    end = begin + change,//結(jié)束位置
    startTime = new Date().getTime();//開始執(zhí)行的時(shí)間
    (function(){
      setTimeout(function(){
        var newTime = new Date().getTime(),//當(dāng)前幀開始的時(shí)間
        timestamp = newTime - startTime;//逝去時(shí)間
        el.style.left = ease(timestamp,begin,change,duration) + "px";//移動(dòng)
        if(duration <= timestamp){
          el.style.left = end + "px";
        }else{
          setTimeout(arguments.callee,25);//每移動(dòng)一次停留25毫秒
        }
      },25)
    })()
  }

接著是各種緩動(dòng)公式大閱兵，共分為十一大類，除了linear。其他類又分為三種。

easeIn方法控制補(bǔ)間如何從開始到最高速度。
easeOut 方法控制補(bǔ)間減速并停在目標(biāo)位置
easeInOut方法同時(shí)控制上述兩者。

具體公式見下面（共31種）。

//***********@author：Robert Penner and cloudgamer*************
//http://www.rzrgm.cn/cloudgamer/archive/2009/01/06/Tween.html
  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;
      },
      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;
      }
    }
  }

<div id="taxiway">
  <div id="move" onclick="transition(this,{ease:Tween.Bounce.easeOut})"></div>
</div>

但我不喜歡flash流派的緩動(dòng)公式，為了使用prototype流派的緩動(dòng)公式，我進(jìn)一步改進(jìn)與抽象化我的緩動(dòng)函數(shù)

//******************@author : 司徒正美************
  var transition = function(el){
    el.style.position = "absolute";
    var options = arguments[1] || {},
    begin =  options.begin,//開始位置
    change = options.change,//變化量
    duration = options.duration || 500,//緩動(dòng)效果持續(xù)時(shí)間
    field = options.field,//必須指定，基本上對(duì)top,left,width,height這個(gè)屬性進(jìn)行設(shè)置
    ftp = options.ftp || 50,
    onStart = options.onStart || function(){},
    onEnd = options.onEnd || function(){},
    ease = options.ease,//要使用的緩動(dòng)公式
    end = begin + change,//結(jié)束位置
    startTime = new Date().getTime();//開始執(zhí)行的時(shí)間
    onStart();
    (function(){
      setTimeout(function(){
        var newTime = new Date().getTime(),//當(dāng)前幀開始的時(shí)間
        timestamp = newTime - startTime,//逝去時(shí)間
        delta = ease(timestamp / duration);
        el.style[field] = Math.ceil(begin + delta * change) + "px"
        if(duration <= timestamp){
          el.style[field] = end + "px";
          onEnd();
        }else{
          setTimeout(arguments.callee,1000/ftp);
        }
      },1000/ftp)
    })()
  }

參數(shù)	類型	說(shuō)明
el	element	必需，為頁(yè)面元素
begin	number	必需，開始的位置
change	number	必需，要移動(dòng)的距離
duration	number	可選，緩動(dòng)效果持續(xù)時(shí)間，默認(rèn)是500ms。建議取300~1000ms。
field	string	必需，要發(fā)生變化的樣式屬性。請(qǐng)?jiān)趖op，left，bottom,right，width與height中選擇。
ftp	number	可選，每秒進(jìn)行多少幀動(dòng)畫，默認(rèn)50幀，保證流暢播放。一些參考資料，日本動(dòng)畫1秒36幀，中國(guó)卡通24幀，賽車游戲60幀。
ease	function	必需，緩動(dòng)公式，參數(shù)為0~1之間的數(shù)?？蓞⒖嘉蚁旅娼o出的45條公式。
onStart	function	可選，在開始時(shí)執(zhí)行。
onEnd	function	可選，在結(jié)束時(shí)執(zhí)行。

prototype流派的緩動(dòng)公式，只需一個(gè)參數(shù)（增至45種）

var tween = {
    easeInQuad: function(pos){
      return Math.pow(pos, 2);
    },

    easeOutQuad: function(pos){
      return -(Math.pow((pos-1), 2) -1);
    },

    easeInOutQuad: function(pos){
      if ((pos/=0.5) < 1) return 0.5*Math.pow(pos,2);
      return -0.5 * ((pos-=2)*pos - 2);
    },

    easeInCubic: function(pos){
      return Math.pow(pos, 3);
    },

    easeOutCubic: function(pos){
      return (Math.pow((pos-1), 3) +1);
    },

    easeInOutCubic: function(pos){
      if ((pos/=0.5) < 1) return 0.5*Math.pow(pos,3);
      return 0.5 * (Math.pow((pos-2),3) + 2);
    },

    easeInQuart: function(pos){
      return Math.pow(pos, 4);
    },

    easeOutQuart: function(pos){
      return -(Math.pow((pos-1), 4) -1)
    },

    easeInOutQuart: function(pos){
      if ((pos/=0.5) < 1) return 0.5*Math.pow(pos,4);
      return -0.5 * ((pos-=2)*Math.pow(pos,3) - 2);
    },

    easeInQuint: function(pos){
      return Math.pow(pos, 5);
    },

    easeOutQuint: function(pos){
      return (Math.pow((pos-1), 5) +1);
    },

    easeInOutQuint: function(pos){
      if ((pos/=0.5) < 1) return 0.5*Math.pow(pos,5);
      return 0.5 * (Math.pow((pos-2),5) + 2);
    },

    easeInSine: function(pos){
      return -Math.cos(pos * (Math.PI/2)) + 1;
    },

    easeOutSine: function(pos){
      return Math.sin(pos * (Math.PI/2));
    },

    easeInOutSine: function(pos){
      return (-.5 * (Math.cos(Math.PI*pos) -1));
    },

    easeInExpo: function(pos){
      return (pos==0) ? 0 : Math.pow(2, 10 * (pos - 1));
    },

    easeOutExpo: function(pos){
      return (pos==1) ? 1 : -Math.pow(2, -10 * pos) + 1;
    },

    easeInOutExpo: function(pos){
      if(pos==0) return 0;
      if(pos==1) return 1;
      if((pos/=0.5) < 1) return 0.5 * Math.pow(2,10 * (pos-1));
      return 0.5 * (-Math.pow(2, -10 * --pos) + 2);
    },

    easeInCirc: function(pos){
      return -(Math.sqrt(1 - (pos*pos)) - 1);
    },

    easeOutCirc: function(pos){
      return Math.sqrt(1 - Math.pow((pos-1), 2))
    },

    easeInOutCirc: function(pos){
      if((pos/=0.5) < 1) return -0.5 * (Math.sqrt(1 - pos*pos) - 1);
      return 0.5 * (Math.sqrt(1 - (pos-=2)*pos) + 1);
    },

    easeOutBounce: function(pos){
      if ((pos) < (1/2.75)) {
        return (7.5625*pos*pos);
      } else if (pos < (2/2.75)) {
        return (7.5625*(pos-=(1.5/2.75))*pos + .75);
      } else if (pos < (2.5/2.75)) {
        return (7.5625*(pos-=(2.25/2.75))*pos + .9375);
      } else {
        return (7.5625*(pos-=(2.625/2.75))*pos + .984375);
      }
    },

    easeInBack: function(pos){
      var s = 1.70158;
      return (pos)*pos*((s+1)*pos - s);
    },

    easeOutBack: function(pos){
      var s = 1.70158;
      return (pos=pos-1)*pos*((s+1)*pos + s) + 1;
    },

    easeInOutBack: function(pos){
      var s = 1.70158;
      if((pos/=0.5) < 1) return 0.5*(pos*pos*(((s*=(1.525))+1)*pos -s));
      return 0.5*((pos-=2)*pos*(((s*=(1.525))+1)*pos +s) +2);
    },

    elastic: function(pos) {
      return -1 * Math.pow(4,-8*pos) * Math.sin((pos*6-1)*(2*Math.PI)/2) + 1;
    },

    swingFromTo: function(pos) {
      var s = 1.70158;
      return ((pos/=0.5) < 1) ? 0.5*(pos*pos*(((s*=(1.525))+1)*pos - s)) :
        0.5*((pos-=2)*pos*(((s*=(1.525))+1)*pos + s) + 2);
    },

    swingFrom: function(pos) {
      var s = 1.70158;
      return pos*pos*((s+1)*pos - s);
    },

    swingTo: function(pos) {
      var s = 1.70158;
      return (pos-=1)*pos*((s+1)*pos + s) + 1;
    },

    bounce: function(pos) {
      if (pos < (1/2.75)) {
        return (7.5625*pos*pos);
      } else if (pos < (2/2.75)) {
        return (7.5625*(pos-=(1.5/2.75))*pos + .75);
      } else if (pos < (2.5/2.75)) {
        return (7.5625*(pos-=(2.25/2.75))*pos + .9375);
      } else {
        return (7.5625*(pos-=(2.625/2.75))*pos + .984375);
      }
    },

    bouncePast: function(pos) {
      if (pos < (1/2.75)) {
        return (7.5625*pos*pos);
      } else if (pos < (2/2.75)) {
        return 2 - (7.5625*(pos-=(1.5/2.75))*pos + .75);
      } else if (pos < (2.5/2.75)) {
        return 2 - (7.5625*(pos-=(2.25/2.75))*pos + .9375);
      } else {
        return 2 - (7.5625*(pos-=(2.625/2.75))*pos + .984375);
      }
    },

    easeFromTo: function(pos) {
      if ((pos/=0.5) < 1) return 0.5*Math.pow(pos,4);
      return -0.5 * ((pos-=2)*Math.pow(pos,3) - 2);
    },

    easeFrom: function(pos) {
      return Math.pow(pos,4);
    },

    easeTo: function(pos) {
      return Math.pow(pos,0.25);
    },

    linear:  function(pos) {
      return pos
    },

    sinusoidal: function(pos) {
      return (-Math.cos(pos*Math.PI)/2) + 0.5;
    },

    reverse: function(pos) {
      return 1 - pos;
    },

    mirror: function(pos, transition) {
      transition = transition || tween.sinusoidal;
      if(pos<0.5)
        return transition(pos*2);
      else
        return transition(1-(pos-0.5)*2);
    },

    flicker: function(pos) {
      var pos = pos + (Math.random()-0.5)/5;
      return tween.sinusoidal(pos < 0 ? 0 : pos > 1 ? 1 : pos);
    },

    wobble: function(pos) {
      return (-Math.cos(pos*Math.PI*(9*pos))/2) + 0.5;
    },

    pulse: function(pos, pulses) {
      return (-Math.cos((pos*((pulses||5)-.5)*2)*Math.PI)/2) + .5;
    },

    blink: function(pos, blinks) {
      return Math.round(pos*(blinks||5)) % 2;
    },

    spring: function(pos) {
      return 1 - (Math.cos(pos * 4.5 * Math.PI) * Math.exp(-pos * 6));
    },

    none: function(pos){
      return 0
    },

    full: function(pos){
      return 1
    }
  }

<!doctype html>
<html dir="ltr" lang="zh-CN">
    <head>
        <meta charset="utf-8"/>
        <meta http-equiv="X-UA-Compatible" content="IE=8">
        <style type="text/css">
            .taxiway{
                width:800px;
                height:100px;
                background:#E8E8FF;
            }
            .move{
                width:100px;
                height:100px;
                background:#a9ea00;
            }
            #panel {
                float:left;
                width:810px
            }
            #panel div{
                float:left;
                width:88px;
                border:1px solid #333;
                height:20px;
                font-size:11px;
            }
            div.transition {
                margin-top: 30px;
                width: 200px;
                height: 200px;
                position: relative;
                margin-bottom:10px;
            }

div.transition div {
                position: absolute;
                height: 1px;
                width: 1px;
                background: #000;
            }

div.transition span {
                display: block;
                position: absolute;
                border-bottom: 1px solid #dadada;
                font-size: 10px;
                color: #888;
                width: 200px;
                left: 0px;
            }
            div.transition div#indicator {
                position:absolute;
                background-color:#a9ea00;
                height: 200px;
                top: 0px;
                left: 0px;
            }

div.transition div#marker {
                background-color: #f00;
                height: 6px;
                width: 6px;
                border-radius: 3px;
                -webkit-border-radius: 3px;
                -moz-border-radius: 3px;
                left: 0px;
                margin-bottom: -3px;
                margin-left: -3px;
            }
            div.transition div#label {
                background: transparent;
                color: #ABD474;
                font-size: 20px;
                height: 20px;
                width: 200px;
                text-align: center;
                top: 80px;
                left: 0px;
                z-index: -1;
            }

</style>
        <script type="text/javascript">
            var getCoords = function(el){
                var box = el.getBoundingClientRect(),
                doc = el.ownerDocument,
                body = doc.body,
                html = doc.documentElement,
                clientTop = html.clientTop || body.clientTop || 0,
                clientLeft = html.clientLeft || body.clientLeft || 0,
                top  = box.top  + (self.pageYOffset || html.scrollTop  ||  body.scrollTop ) - clientTop,
                left = box.left + (self.pageXOffset || html.scrollLeft ||  body.scrollLeft) - clientLeft
                return { 'top': top, 'left': left };
            };

easeOutQuad: function(pos){
                    return -(Math.pow((pos-1), 2) -1);
                },

easeInOutQuad: function(pos){
                    if ((pos/=0.5) < 1) return 0.5*Math.pow(pos,2);
                    return -0.5 * ((pos-=2)*pos - 2);
                },

easeInCubic: function(pos){
                    return Math.pow(pos, 3);
                },

easeOutCubic: function(pos){
                    return (Math.pow((pos-1), 3) +1);
                },

easeInOutCubic: function(pos){
                    if ((pos/=0.5) < 1) return 0.5*Math.pow(pos,3);
                    return 0.5 * (Math.pow((pos-2),3) + 2);
                },

easeInQuart: function(pos){
                    return Math.pow(pos, 4);
                },

easeOutQuart: function(pos){
                    return -(Math.pow((pos-1), 4) -1)
                },

easeInOutQuart: function(pos){
                    if ((pos/=0.5) < 1) return 0.5*Math.pow(pos,4);
                    return -0.5 * ((pos-=2)*Math.pow(pos,3) - 2);
                },

easeInQuint: function(pos){
                    return Math.pow(pos, 5);
                },

easeOutQuint: function(pos){
                    return (Math.pow((pos-1), 5) +1);
                },

easeInOutQuint: function(pos){
                    if ((pos/=0.5) < 1) return 0.5*Math.pow(pos,5);
                    return 0.5 * (Math.pow((pos-2),5) + 2);
                },

easeInSine: function(pos){
                    return -Math.cos(pos * (Math.PI/2)) + 1;
                },

easeOutSine: function(pos){
                    return Math.sin(pos * (Math.PI/2));
                },

easeInOutSine: function(pos){
                    return (-.5 * (Math.cos(Math.PI*pos) -1));
                },

easeInExpo: function(pos){
                    return (pos==0) ? 0 : Math.pow(2, 10 * (pos - 1));
                },

easeOutExpo: function(pos){
                    return (pos==1) ? 1 : -Math.pow(2, -10 * pos) + 1;
                },

easeInOutExpo: function(pos){
                    if(pos==0) return 0;
                    if(pos==1) return 1;
                    if((pos/=0.5) < 1) return 0.5 * Math.pow(2,10 * (pos-1));
                    return 0.5 * (-Math.pow(2, -10 * --pos) + 2);
                },

easeInCirc: function(pos){
                    return -(Math.sqrt(1 - (pos*pos)) - 1);
                },

easeOutCirc: function(pos){
                    return Math.sqrt(1 - Math.pow((pos-1), 2))
                },

easeInOutCirc: function(pos){
                    if((pos/=0.5) < 1) return -0.5 * (Math.sqrt(1 - pos*pos) - 1);
                    return 0.5 * (Math.sqrt(1 - (pos-=2)*pos) + 1);
                },

easeOutBounce: function(pos){
                    if ((pos) < (1/2.75)) {
                        return (7.5625*pos*pos);
                    } else if (pos < (2/2.75)) {
                        return (7.5625*(pos-=(1.5/2.75))*pos + .75);
                    } else if (pos < (2.5/2.75)) {
                        return (7.5625*(pos-=(2.25/2.75))*pos + .9375);
                    } else {
                        return (7.5625*(pos-=(2.625/2.75))*pos + .984375);
                    }
                },

easeInBack: function(pos){
                    var s = 1.70158;
                    return (pos)*pos*((s+1)*pos - s);
                },

easeOutBack: function(pos){
                    var s = 1.70158;
                    return (pos=pos-1)*pos*((s+1)*pos + s) + 1;
                },

easeInOutBack: function(pos){
                    var s = 1.70158;
                    if((pos/=0.5) < 1) return 0.5*(pos*pos*(((s*=(1.525))+1)*pos -s));
                    return 0.5*((pos-=2)*pos*(((s*=(1.525))+1)*pos +s) +2);
                },

elastic: function(pos) {
                    return -1 * Math.pow(4,-8*pos) * Math.sin((pos*6-1)*(2*Math.PI)/2) + 1;
                },

swingFromTo: function(pos) {
                    var s = 1.70158;
                    return ((pos/=0.5) < 1) ? 0.5*(pos*pos*(((s*=(1.525))+1)*pos - s)) :
                        0.5*((pos-=2)*pos*(((s*=(1.525))+1)*pos + s) + 2);
                },

swingFrom: function(pos) {
                    var s = 1.70158;
                    return pos*pos*((s+1)*pos - s);
                },

swingTo: function(pos) {
                    var s = 1.70158;
                    return (pos-=1)*pos*((s+1)*pos + s) + 1;
                },

bounce: function(pos) {
                    if (pos < (1/2.75)) {
                        return (7.5625*pos*pos);
                    } else if (pos < (2/2.75)) {
                        return (7.5625*(pos-=(1.5/2.75))*pos + .75);
                    } else if (pos < (2.5/2.75)) {
                        return (7.5625*(pos-=(2.25/2.75))*pos + .9375);
                    } else {
                        return (7.5625*(pos-=(2.625/2.75))*pos + .984375);
                    }
                },

bouncePast: function(pos) {
                    if (pos < (1/2.75)) {
                        return (7.5625*pos*pos);
                    } else if (pos < (2/2.75)) {
                        return 2 - (7.5625*(pos-=(1.5/2.75))*pos + .75);
                    } else if (pos < (2.5/2.75)) {
                        return 2 - (7.5625*(pos-=(2.25/2.75))*pos + .9375);
                    } else {
                        return 2 - (7.5625*(pos-=(2.625/2.75))*pos + .984375);
                    }
                },

easeFromTo: function(pos) {
                    if ((pos/=0.5) < 1) return 0.5*Math.pow(pos,4);
                    return -0.5 * ((pos-=2)*Math.pow(pos,3) - 2);
                },

easeFrom: function(pos) {
                    return Math.pow(pos,4);
                },

easeTo: function(pos) {
                    return Math.pow(pos,0.25);
                },

linear:  function(pos) {
                    return pos
                },

sinusoidal: function(pos) {
                    return (-Math.cos(pos*Math.PI)/2) + 0.5;
                },

reverse: function(pos) {
                    return 1 - pos;
                },

mirror: function(pos, transition) {
                    transition = transition || tween.sinusoidal;
                    if(pos<0.5)
                        return transition(pos*2);
                    else
                        return transition(1-(pos-0.5)*2);
                },

flicker: function(pos) {
                    var pos = pos + (Math.random()-0.5)/5;
                    return tween.sinusoidal(pos < 0 ? 0 : pos > 1 ? 1 : pos);
                },

wobble: function(pos) {
                    return (-Math.cos(pos*Math.PI*(9*pos))/2) + 0.5;
                },

pulse: function(pos, pulses) {
                    return (-Math.cos((pos*((pulses||5)-.5)*2)*Math.PI)/2) + .5;
                },

blink: function(pos, blinks) {
                    return Math.round(pos*(blinks||5)) % 2;
                },

spring: function(pos) {
                    return 1 - (Math.cos(pos * 4.5 * Math.PI) * Math.exp(-pos * 6));
                },

none: function(pos){
                    return 0
                },

full: function(pos){
                    return 1
                }
            }

if (typeof Array.prototype['max'] == 'undefined') {
                Array.prototype.map = function(fn, thisObj) {
                    var scope = thisObj || window;
                    var a = [];
                    for ( var i=0, j=this.length; i < j; ++i ) {
                        a.push(fn.call(scope, this[i], i, this));
                    }
                    return a;
                };
                Array.prototype.max = function(){
                    return Math.max.apply({},this)
                }
                Array.prototype.min = function(){
                    return Math.min.apply({},this)
                }
            }

var range = function(start,end){
                var _range = []
                for(var i = start,l=end-start;i<l;i++){
                    _range.push(i)
                }
                return _range
            }

}
        </script>
        <title>緩動(dòng)BY司徒正美</title>
    </head>
    <body>
        <div class="taxiway">
            <div class="move" onclick="transition(this,{field:'left',begin:parseFloat(getCoords(this).left),change:700,ease:tween.bouncePast})"></div>
        </div>
        <div class="taxiway">
            <div class="move" onclick="transition(this,{field:'width',begin:parseFloat(getStyle(this,'width')),change:300,ease:tween.spring})"></div>
        </div>
<span class="clear"></span>
<h2>請(qǐng)點(diǎn)擊下表的格子</h2>
        <div id="transition" class="transition">

</div>

</body>
</html>

除了這45條公式外，我們還可以制定自己的緩動(dòng)公式。正如我在上面表格中提到，它在運(yùn)行過(guò)程是不執(zhí)行回調(diào)函數(shù)時(shí)，但你們可以在運(yùn)行框中看到，我可以實(shí)現(xiàn)一邊移動(dòng)一邊記錄點(diǎn)的坐標(biāo)。這是怎樣實(shí)現(xiàn)的呢？我們只要把上面的緩動(dòng)公式的任何一條塞進(jìn)一個(gè)只有一個(gè)參數(shù)的函數(shù)就行了。當(dāng)然此函數(shù)要有返回，供繼續(xù)向下調(diào)用。以下就是一個(gè)模板：

  var myTween = function(pos){ //緩動(dòng)公式
      var value = tween[ease](pos);
      //***********這上面是固定的**************
      indicator.style.display = "block";
      marker.style.display = "block";
      marker.style.left = Math.round((pos*200))+'px';
      marker.style.bottom = Math.round(((value*200)-min)*factor)+'px';
      label.innerHTML = Math.round((pos*200))+'px';
      //************這下面是固定的*************
      return value;
    }

更多示例，不懂再留言給我。

 <div class="taxiway">
  <div class="move" onclick="transition(this,{field:'left',begin:parseFloat(getCoords(this).left),change:700,ease:tween.bouncePast})"></div>
</div>
<div class="taxiway">
  <div class="move" onclick="transition(this,{field:'width',begin:parseFloat(getStyle(this,'width')),change:300,ease:tween.spring})"></div>
</div>

posted on 2009-09-17 04:18 司徒正美閱讀(12533) 評(píng)論(34) 收藏舉報(bào)

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