//容器对象,滑动对象,切换数量
var SlideTrans = function(container, slider, count, options) {
	this._slider = this.$$(slider);
	this._container = this.$$(container);//容器对象
	this._timer = null;//定时器
	this._count = Math.abs(count);//切换数量
	this._target = 0;//目标值
	this._t = this._b = this._c = 0;//tween参数
	
	this.Index = 0;//当前索引
	
	this.SetOptions(options);
	
	this.Auto = !!this.options.Auto;
	this.Duration = Math.abs(this.options.Duration);
	this.Time = Math.abs(this.options.Time);
	this.Pause = Math.abs(this.options.Pause);
	this.Tween = this.options.Tween;
	this.onStart = this.options.onStart;
	this.onFinish = this.options.onFinish;
	
	var bVertical = !!this.options.Vertical;
	this._css = bVertical ? "top" : "left";//方向
	
	//样式设置
	var p = this.CurrentStyle(this._container).position;
	p == "relative" || p == "absolute" || (this._container.style.position = "relative");
	this._container.style.overflow = "hidden";
	this._slider.style.position = "absolute";
	
	this.Change = this.options.Change ? this.options.Change :
		this._slider[bVertical ? "offsetHeight" : "offsetWidth"] / this._count;
};
SlideTrans.prototype = {
  //设置默认属性
  SetOptions: function(options) {
	this.options = {//默认值
		Vertical:	true,//是否垂直方向（方向不能改）
		Auto:		true,//是否自动
		Change:		0,//改变量
		Duration:	30,//滑动持续时间
		Time:		10,//滑动延时
		Pause:		5000,//停顿时间(Auto为true时有效)
		onStart:	function(){},//开始转换时执行
		onFinish:	function(){},//完成转换时执行
		Tween:		this.TweenFC.Quart.easeOut//tween算子
	};
	this.Extend(this.options, options || {});
  },
  //开始切换
  Run: function(index) {
	//修正index
	index == undefined && (index = this.Index);
	index < 0 && (index = this._count - 1) || index >= this._count && (index = 0);
	//设置参数
	this._target = -Math.abs(this.Change) * (this.Index = index);
	this._t = 0;
	this._b = parseInt(this.CurrentStyle(this._slider)[this.options.Vertical ? "top" : "left"]);
	this._c = this._target - this._b;
	
	this.onStart();
	this.Move();
  },
  //移动
  Move: function() {
	clearTimeout(this._timer);
	//未到达目标继续移动否则进行下一次滑动
	if (this._c && this._t < this.Duration) {
		this.MoveTo(Math.round(this.Tween(this._t++, this._b, this._c, this.Duration)));
		this._timer = setTimeout(this.Bind(this, this.Move), this.Time);
	}else{
		this.MoveTo(this._target);
		this.onFinish();
		this.Auto && (this._timer = setTimeout(this.Bind(this, this.Next), this.Pause));
	}
  },
  //移动到
  MoveTo: function(i) {
	this._slider.style[this._css] = i + "px";
  },
  //下一个
  Next: function() {
	this.Run(++this.Index);
  },
  //上一个
  Previous: function() {
	this.Run(--this.Index);
  },
  //停止
  Stop: function() {
	clearTimeout(this._timer); this.MoveTo(this._target);
  },
  
  $$ : function (id) {
  return "string" == typeof id ? document.getElementById(id) : id;
  },
  
  Extend : function(destination, source) {
  for (var property in source) {
    destination[property] = source[property];
  }
  return destination;
  },
  
  CurrentStyle : function(element){
  return element.currentStyle || document.defaultView.getComputedStyle(element, null);
  },
  
  Bind : function(object, fun) {
  var args = Array.prototype.slice.call(arguments).slice(2);
  return function() {
    return fun.apply(object, args.concat(Array.prototype.slice.call(arguments)));
  }
  },
  
  forEach : function(array, callback, thisObject){
  if(array.forEach){
    array.forEach(callback, thisObject);
  }else{
    for (var i = 0, len = array.length; i < len; i++) { callback.call(thisObject, array[i], i, array); }
  }
  },
  
  TweenFC : {
  Quart: {
    easeOut: function(t,b,c,d){
      return -c * ((t=t/d-1)*t*t*t - 1) + b;
    }
  },
  Back: {
    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;
    }
  },
  Bounce: {
    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;
      }
    }
  }
  }
  
};