/*
  instance:创建的实例名称
  marquee:滚动区域容器的ID，要求无填充，无边框，overflow为hidden
  direction:滚动方向，值分别为：up,down,left,right
  delay:滚动的速度，值最小为1，值越小越快
  amount:滚动步进量，值最小为1，值越大越快
*/

 function Marquee(instance,marquee,direction,delay,amount){
  this.instance =instance;//实例名称
  this.marquee = document.getElementById(marquee);
  this.delay = delay;
  if(this.delay==null){
   this.delay = 1;
  }
  this.amount = amount;
  if(this.amount==null){
   this.amount = 1;
  }
  this.direction = direction;
  this.width = this.marquee.clientWidth;
  this.height = this.marquee.clientHeight;
//  this.container = document.createElement("table");
//  this.container.border=0;
//  this.container.cellspacing="0"
//  this.container.cellpadding="0"
  var _HTML = this.marquee.innerHTML;
//  this.marquee.innerHTML = "";
//  this.marquee.appendChild(this.container);
//  var _tr = this.container.insertRow(this.container.rows.length);
//  var _td = _tr.insertCell(_tr.cells.length);
//  _td.innerHTML = _HTML;
//  this.scrollHeight = this.container.clientHeight;
//  this.scrollWidth = this.container.clientWidth;
  this.scrollWidth = this.marquee.clientWidth;
  var lis = document.getElementById(marquee).getElementsByTagName("li");
  this.scrollHeight = 0;
  for(var index=0;index<lis.length;index++)
  {
       this.scrollHeight += lis.item(index).offsetHeight;
  }
  switch(this.direction.toLowerCase()){
   case "up":
   case "down":
    _HTML = this.marquee.innerHTML;
    if(this.scrollHeight>=this.height){
//     var _tr = this.container.insertRow(this.container.rows.length);
//     var _td = _tr.insertCell(_tr.cells.length);
//     _td.innerHTML = _HTML;
    this.marquee.innerHTML += _HTML;
     this.scrollHeight += this.scrollHeight; 
    }
//    if(this.direction.toLowerCase()=="down"){
//     this.marquee.scrollTop=this.scrollHeight/2;
//    }
    break;
   default:
     _HTML = this.marquee.getElementsByTagName("ul").item(0).innerHTML;
    if(this.scrollWidth>=this.width){
     this.marquee.getElementsByTagName("ul").item(0).innerHTML += _HTML;
    this.marquee.getElementsByTagName("ul").item(0).style.width = (this.marquee.getElementsByTagName("ul").item(0).getElementsByTagName("li").length * this.marquee.getElementsByTagName("ul").item(0).getElementsByTagName("li").item(0).offsetWidth) + "px";
//     var _td = _tr.insertCell(_tr.cells.length);
//     _td.innerHTML = _HTML;
//     this.scrollWidth += this.scrollWidth;
        this.scrollWidth = this.marquee.getElementsByTagName("ul").item(0).offsetWidth;
    }
    
  }
  
  this.marquee.m = this;
  
  this.intervalId = null;
  this.marquee.onmouseover = function (){
   this.m.Stop();
  }
  this.marquee.onmouseout = function (){
   this.m.Start();
  }
  this.Start();
 }
 Marquee.prototype.Start = function (){
  this.intervalId = setInterval(this.instance+".Scroll()",this.delay)
  //this.Scroll();
 }
 Marquee.prototype.Stop = function (sender){
  if(this.intervalId!=null){
   clearInterval(this.intervalId);
  }
 }
 Marquee.prototype.Scroll = function (){
  switch(this.direction.toLowerCase()){
   case "up":
    if((this.marquee.scrollTop+this.height)>=this.scrollHeight){
     this.marquee.scrollTop-=this.scrollHeight/2
    }
    if(this.scrollHeight>this.height){
     this.marquee.scrollTop+=this.amount;
    }
    break;
   case "down":
    if(this.marquee.scrollTop<=0){
     this.marquee.scrollTop+=this.scrollHeight/2
    }
    if(this.scrollHeight>this.height){
     this.marquee.scrollTop-=this.amount;
    }
    break;
   case "right":
    if(this.marquee.scrollLeft<=0){
     this.marquee.scrollLeft+=this.scrollWidth/2
    }
    if(this.scrollWidth>this.width){
     this.marquee.scrollLeft-=this.amount;
    }
    break;
   default:
    if((this.marquee.scrollLeft+this.width)>=this.scrollWidth){
//     this.marquee.scrollLeft-=this.scrollWidth/2
       this.marquee.scrollLeft-=this.marquee.getElementsByTagName("ul").item(0).offsetWidth/2;
    }
    if(this.scrollWidth>this.width){
     this.marquee.scrollLeft+=this.amount;
    }
  }
 }