function stopdefault(e) {// 禁止浏览器默认行为
	var e= e || event;
	if (e.preventdefault) {
		e.preventdefault();
	} else {
		window.event.returnvalue = false;
	}

	return false;
}

//模拟滚动条
function imitatescrollh(scrollbox, scrollobj, scrollbar, scrollbtn)
{//scrollbox被滚动对象外框，scrollobj被滚动对象，scrollbar滚动条块，滚动条按钮
	this.init(scrollbox, scrollobj, scrollbar, scrollbtn);
}

imitatescrollh.prototype = {
	scale:function() {//被滚动对象与被滚动对象外框的高度比例计算
		return (this.scrollobj.scrollwidth/this.scrollbox.clientwidth);
	},
	scrollbtnmousedown:function(ev) {//滚动按钮按下
		var _this = this;
		var disy = ev.clientx - this.scrollbtn.offsetleft;//鼠标y坐标距离滚动按钮头部的距离
		var maxtop =  this.scrollbar.clientwidth - this.scrollbtn.offsetwidth;

		document.onmousemove = function(ev) {
			if (document.all) {//ie 禁止选择
				document.body.onselectstart = new function("return false");
			} else {// chrome, ff
				$("body").addclass('chromeonselectstart')
			}

			var oevent = ev || event;
			var t = oevent.clientx - disy;
			t = t > maxtop ? maxtop : t;
			t = t < 0 ? 0 : t;

			 _this.scrollbtn.style.left = t + "px";
			 //_this.scrollobj.style.left = -t / _this.scrollbar.clientwidth * _this.scrollobj.scrollwidth + "px";
			  _this.scrollobj.style.left = -t / (_this.scrollbar.clientwidth-_this.scrollbtn.offsetwidth) * (_this.scrollobj.scrollwidth-_this.scrollbox.clientwidth) + "px";
		};
		document.onmouseup = function() {
			if (document.all) {//ie 解除禁止选择
				document.body.onselectstart = new function("return true");
			} else {// chrome, ff
				$("body").removeclass('chromeonselectstart')
			}

			document.onmousemove = document.onmouseup = null;//清除move和up事件
		};
	},
	scrollboxmousewheel:function(ev) {//鼠标滚轮滚动
		var direct = 0;
		var topcur = this.scrollbtn.offsetleft;
		var maxtop =  this.scrollbar.clientwidth - this.scrollbtn.offsetwidth;
		//滚轮每次滚动，滚动按钮该走的距离，测试chrome滚8次差不多一屏
		var directtop = this.scrollbox.clientwidth / 8 / this.scrollobj.scrollwidth * this.scrollbar.clientwidth;
		directtop = directtop>0 ? math.ceil(directtop) : math.floor(directtop);

		stopdefault(ev);//禁止浏览器自身的滚动条滚动效果
		if (ev.wheeldelta)  {//ie/opera/chrome 
			direct = ev.wheeldelta;
		} else if (ev.detail) {//firefox 
			direct = ev.detail * (-1);
		}

		if(parsefloat(direct) > 0) {
			var topend = topcur - directtop;
			if (topend < 0) {topend = 0;}
		} else {
			var topend = topcur + directtop;
			topend = topend>maxtop ? maxtop : topend;
		}

		this.scrollbtn.style.left = topend + "px";
		//this.scrollobj.style.left = -topend / this.scrollbar.clientwidth * this.scrollobj.scrollwidth + "px";
		this.scrollobj.style.left = -topend / (this.scrollbar.clientwidth-this.scrollbtn.offsetwidth) * (this.scrollobj.scrollwidth-this.scrollbox.clientwidth) + "px";
	},
	init:function(scrollbox, scrollobj, scrollbar, scrollbtn) {//初始化
		this.scrollbox = typeof scrollbox == "string" ? document.getelementbyid(scrollbox) : scrollbox;
		this.scrollobj = typeof scrollobj == "string" ? document.getelementbyid(scrollobj) : scrollobj;
		this.scrollbar = typeof scrollbar == "string" ? document.getelementbyid(scrollbar) : scrollbar;
		this.scrollbtn = typeof scrollbtn == "string" ? document.getelementbyid(scrollbtn) : scrollbtn;
		var scale = this.scale();////被滚动对象与被滚动对象外框的高度比例

		if (scale <= 1) {//判断是否达到产生滚动条的条件
			//this.scrollobj.style.width   = "100%";
			this.scrollbar.style.display = "none";
			return;
		} else {
			//this.scrollobj.style.width   = "95%";
			this.scrollbar.style.display = "block";
		}

		// if(_this.scrollobj.scrollwidth+_this.scrollobj.offsetleft < _this.scrollbox.clientwidth)
		// {//判断被滚动对象是否滚过头了
		// 	 _this.scrollobj.style.left = _this.scrollbox.clientwidth-_this.scrollobj.scrollwidth+"px";
		// }

		//初始化滚动按钮的高度和top值
		//this.scrollbtn.style.height = 20 + "px"; //设定滚动按钮的高度
		//this.scrollbtn.style.left = -this.scrollobj.offsetleft/this.scrollobj.scrollwidth*this.scrollbar.clientwidth + "px";

		var _this = this;
		this.scrollbtn.onmousedown = function(e) {//滚动按钮拖拽事件
			var e = e || event;
			_this.scrollbtnmousedown(e);
		};

		//绑定滚轮事件
		if (this.scrollbox.addeventlistener) {//ff3.5以下
			this.scrollbox.addeventlistener("dommousescroll", function(e) {
				var e = e || event;
				_this.scrollboxmousewheel(e)
			}, false);
		}
		//w3c
		this.scrollbox.onmousewheel = function(e) {
			var e = e || event;
			_this.scrollboxmousewheel(e)
		}; //ie/opera/chrome

		// $("#scrollobj").mousemove(function(e){
		// 	// $(this).stop().animate({
		// 	// 	left : - l
		// 	// }, 1000, "easeoutexpo")

		// 	var _w = $(window).width(),
	 //            _liw = _w*0.17,
	 //            _sw = _w*0.83,
	 //            _ulw = $("#scrollobj li").length*248;
	 //        var left=-1*((_ulw-_sw)/_w)*(e.pagex);
	 //        $(this).css({"left":left});
	 //        var s = (_ulw-_sw)/_w
	 //        var l = -1*$("#scrollbar").width()*((left/(_w*s))+0.135);
	 //        $("#scrollbtn").css('left', l);
		// })
	}
}