var $ = function (id) {
	return "string" == typeof id ? document.getelementbyid(id) : id;
};

var extend = function(destination, source) {
	for (var property in source) {
		destination[property] = source[property];
	}
	return destination;
}

var currentstyle = function(element){
	return element.currentstyle || document.defaultview.getcomputedstyle(element, null);
}

var 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)));
	}
}

var tween = {
	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;
			}
		}
	}
}


//容器对象,滑动对象,切换数量
var slidetrans = function(container, slider, count, options) {
	this._slider = $(slider);
	this._container = $(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 = 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:	10,//滑动持续时间
		time:		10,//滑动延时
		pause:		3000,//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:		tween.quart.easeout//tween算子
	};
	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(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(bind(this, this.move), this.time);
	}else{
		this.moveto(this._target);
		this.auto && (this._timer = settimeout(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);
  }
};