function hexunRoll(){
    this.rolltext='';
		this.rollTextCopy='';
		this.rollArea='';
		this.rollGap=0;
		this.rollPos=0;
		this.preItem ='';
		this.nextItem = '';
		this.hexunRoll ='';
	}
	hexunRoll.prototype.init=function(){
		this.rollTextCopy.innerHTML=this.rolltext.innerHTML;		
		this.hexunRoll.obj=this;
		this.hexunRoll.onmouseover= function(){
			var _hexunRoll=this.obj
			if(_hexunRoll.rollTimer) clearTimeout(_hexunRoll.rollTimer);
		}
		this.hexunRoll.onmouseout= function(){
			var _hexunRoll=this.obj
			_hexunRoll.startRoll();
		}
		this.preItem.obj=this;
		this.preItem.onclick=function(){
			var _preItem=this.obj;
			_preItem.showPreItem();
			}
	  this.nextItem.obj=this;
		this.nextItem.onclick=function(){
			var _nextItem=this.obj;
			_nextItem.showNextItem();
			}
		}
	hexunRoll.prototype._roll=function(){

		var s = 0,_this = this;

		var timer = setInterval(function(){
			if(s >= _this.rollGap){
				clearInterval(timer);

				_this.rollPos += _this.rollGap;
				return;
			}

			if(_this.rollArea.scrollTop >= _this.rollHeight){
				_this.rollArea.scrollTop = _this.rollPos = 0;
			}

			s += 1;
			_this.rollArea.scrollTop = _this.rollPos + s;
		
		},30);
	}
		hexunRoll.prototype.startRoll=function(){
			   	var _this = this;
					this.rollHeight = this.rolltext.offsetHeight;
			   
					this.rollTimer = setInterval(function(){
						_this._roll();
					},3000);
			}
			
			hexunRoll.prototype.showNextItem=function(){
				if(this.rollArea.scrollTop >= this.rollHeight){
					this.rollArea.scrollTop = this.rollPos = 0;
				}else{
					this.rollArea.scrollTop += this.rollGap;
					this.rollPos += this.rollGap;
				}		
	}
	    hexunRoll.prototype.showPreItem=function(){
					if(this.rollArea.scrollTop == 0){
						this.rollArea.scrollTop = this.rollPos = this.rollHeight;
					}else{
						this.rollArea.scrollTop -= this.rollGap;
						this.rollPos -= this.rollGap;
					}
	}