//JS模拟Marquee连续滚屏效果
//IE 6.0 测试通过
//FireFox 1.5.0.7 测试通过
//Opera 9.02 测试通过
//NetScape 8.1测试通过
//intro:
/*
  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;
	this.amount = amount;
	
	if(this.delay==null){
		this.delay = 1;
	}	
	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;
	
	switch(this.direction.toLowerCase()){
	case "up":
	case "down":
		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.scrollHeight = this.container.clientHeight;
		}
		if(this.direction.toLowerCase()=="down"){
			this.marquee.scrollTop=this.scrollHeight/2;
		}
		break;
	default:
		if(this.scrollWidth>=this.width){
			var _td = _tr.insertCell(_tr.cells.length);
			_td.innerHTML = _HTML;
			this.scrollWidth = this.container.clientWidth;
		}

	}

	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
			}
			if(this.scrollWidth>this.width){
				this.marquee.scrollLeft+=this.amount;
			}
	}
}