function Slider(param1,param2){
//	this.constructor.apply(this, arguments);
	this.constructor(param1,param2);
}
    
Slider.prototype = { 

	el:null,
	initTop:null,
	interval:50,
	myInt:null,
	anim:true,
	sizeheight:100,
	position:"CENTER",
	POSITIONENT_CER:"CENTER",
	POSITION_TOP:"TOP",
	POSITION_BOTTOM:"BOTTOM",
	firstrender:true,
        isIE6:false,

	constructor:function(param1,param2) {
		this.el = param1;
		if(param2 != undefined) this.anim = param2;
	},

	initialize:function()  
	{  
            this.isIE6 = /*@cc_on!@*/false; 
	    this.initTop = this.el.offsetTop || this.getTop( { el:this.el } );  
            if(this.anim){
              this.el.style.position = 'absolute';
            }else if(this.isIE6){
              this.el.style.position = 'absolute';
            }else{
              this.el.style.position = 'fixed';
            }

	    try {  
		if(this.anim) window.addEventListener('scroll', this.delegate(this,this.scrollEvent), false);
                else if(this.isIE6) window.addEventListener('scroll', this.delegate(this,this.scrollEvent),false);
		window.addEventListener('resize', this.delegate(this,this.scrollEvent), false);  
	    } catch (e) {  
		if(this.anim) window.attachEvent('onscroll',this.delegate(this,this.scrollEvent));  
                else if(this.isIE6) window.attachEvent('onscroll',this.delegate(this,this.scrollEvent));
		window.attachEvent('onresize',this.delegate(this,this.scrollEvent));  
	    }  
	    this.scrollEvent();
	    this.el.style.visibility = 'visible';
	},

	scrollEvent:function() {  

		var s = this;
		var trgSizeHeight = this.sizeheight;
		if(this.anim && !this.firstrender){
		
			clearInterval(s.myInt);
			
			//center
			s.myInt = setInterval(function(){  
				var myTop = s.el.offsetTop || s.getTop( { el:s.el } ); 
				
				var cur = s.getPositionTop();
				if(s.position == s.POSITION_CENTER){
					cur = cur + s.getWindowHeight() /2 - trgSizeHeight / 2;
				}else if(s.position == s.POSITION_TOP){
				}else{
					cur = cur + s.getWindowHeight() - trgSizeHeight;
				}
				
				
				var d = cur-myTop; 
				if(Math.abs(d)>1) {
					if( cur >= s.initTop )
					{
					    var y = myTop + d/3;  
					    s.el.style.top = s.setPx(y);  
					} else {
					    s.el.style.top = s.setPx(s.initTop);  
					    clearInterval(s.myInt);  
					}
				} else {
					s.el.style.top = s.setPx(cur);  
					clearInterval(s.myInt);  
				}
			},s.interval);
			
		}else{
                        if(this.isIE6){
                          var myTop = s.getPositionTop();
			  var cur;
			  if(s.position == s.POSITION_CENTER){
				cur = myTop + s.getWindowHeight() /2 - trgSizeHeight / 2;
			  }else if(s.position == s.POSITION_TOP){
                                cur = myTop;
		  	  }else{
				cur = myTop + s.getWindowHeight() - trgSizeHeight;
			  }
                        }else{
			  var cur;
			  if(s.position == s.POSITION_CENTER){
				cur = s.getWindowHeight() /2 - trgSizeHeight / 2;
			  }else if(s.position == s.POSITION_TOP){
                                cur = 0;
		  	  }else{
				cur = s.getWindowHeight() - trgSizeHeight;
			  }
                        }
			s.el.style.top = s.setPx(cur);  
		}
                this.firstrender = false;
	},

	getTop:function(args)
	{  
	    var el = args.el;  
	    var tagName = el.tagName;  
	    var top = args.top||0;  
	    if(tagName=='body'||tagName=='BODY')  
	    {  
		return top;  
	    } else if(tagName=='html'||tagName=='HTML')  
	    {  
		return top;  
	    } else {  
		return arguments.callee( { el:el.offsetParent, top:top += el.offsetTop } );  
	    }   
	},


	getPositionTop:function(){
		return document.body.scrollTop || document.documentElement.scrollTop;
	},


	getWindowHeight:function(){
		return document.documentElement.clientHeight || document.body.clientHeight;
	},


	/* utils */
	
	setPx:function(num){  
	    return (Math.round(num))+'px';  
	},
	
	delegate:function( that, thatMethod ){
	    return function() { return thatMethod.call(that); }
  	}
	
};


function backToTop() {
  var x1 = x2 = x3 = 0;
  var y1 = y2 = y3 = 0;
  if (document.documentElement) {
      x1 = document.documentElement.scrollLeft || 0;
      y1 = document.documentElement.scrollTop || 0;
  }
  if (document.body) {
      x2 = document.body.scrollLeft || 0;
      y2 = document.body.scrollTop || 0;
  }
  x3 = window.scrollX || 0;
  y3 = window.scrollY || 0;
  var x = Math.max(x1, Math.max(x2, x3));
  var y = Math.max(y1, Math.max(y2, y3));
  window.scrollTo(Math.floor(x / 2), Math.floor(y / 2));
  if (x > 0 || y > 0) {
      window.setTimeout(backToTop, 25);
  }
}