//scrollPanel 浮动层(JQ对象)
//speed滚动速度
//scrollPanel样式系列
//closePanel关闭按键
//freesky
function Scroll(scrollPanel,speed,cssParameter,closePanel){
	var _this=this;
	var _scrollPanelTop;
	var _scrollPanelLastTop=0;
	var _docSrcollTop;
	var _percent;
	var _mysrcoll;
	_this._scrollPanel=$("#scroll_panel");//浮动层(JQ对象)
	_this._speed=1;//滚动速度
	_this._closePanel=$("#closePanel")//关闭按键
	this.start=function(){
		_scrollPanelTop=(_this._scrollPanel.css("top")!='NaN')?parseInt(_this._scrollPanel.css("top")):10;
		_scrollPanelLastTop=_scrollPanelTop;
		_mysrcoll=window.setInterval(_this.work,_this._speed)
	}
	this.work=function(){
		_docSrcollTop=parseInt($(document).scrollTop())
		_percent=(_docSrcollTop-_scrollPanelLastTop)/10;
		if(_percent>0){
			_percent=Math.ceil(_percent)
		}
		else{
			_percent=Math.floor(_percent)
		}
		_scrollPanelLastTop=_scrollPanelLastTop+_percent
		_this._scrollPanel.css("top",_scrollPanelLastTop+_scrollPanelTop);
	}
	this.close=function(){
	window.clearInterval(_mysrcoll);
	_this._scrollPanel.css("display","none");
	}
	var init=function(){//模仿构造函数
		_this._scrollPanel = $(scrollPanel || _this._scrollPanel); 
		_this._closePanel = $(closePanel || _this._closePanel); 
		_this._speed = speed || _this._speed; 
		_this._scrollPanel.css('position','absolute');
		_this._scrollPanel.css('z-index',9999);
		_this._scrollPanel.css(cssParameter);
		_this._closePanel.bind("click",function(){_this.close()})
	}
	init()
	
	
};