/******************************
 *Filename:      bglink.js
 *Version:       1.0.0(2009-4-16)
 *Website:       http://
 *Author:        S.S.L
*******************************/
function Bgad(){
	var o = this;
	var adheight,ladurl,radurl;
	
	/*设置bgad的样式*/
	var adcontainer_style = {
		"id":"newbgad",
		"width":"1002px",
		"margin":"0 auto",
		"position":"relative"
	}
	
	function getAdContainer(){
		var ad = document.createElement( "div" );
		
		/*将样式设置到div*/
		ad.id= adcontainer_style.id;
		ad.style.width = adcontainer_style.width;
		ad.style.position = adcontainer_style.position;
		ad.style.margin = adcontainer_style.margin;
		
		return ad;
	}
	
	function setAdContainer( adcontainer,ad1,ad2 ){
		adcontainer.appendChild( ad1 );
		adcontainer.appendChild( ad2 );
		
		//document.body.appendChild( adcontainer );
		document.body.style.overflowX = "hidden";
		document.body.insertBefore( adcontainer,document.body.childNodes[0] );
	}
	
	//获取广告容器里面的div
	function getAd( url,id,x ){
		ad = document.createElement( "div" );
		
		ad.id = id;
		
		ad.style.position = "absolute";
		ad.style.cursor = "pointer";

		if( x != undefined )
			setPos( ad,x );
		else		
			setPos( ad );
		
		//ad.style.border = "1px solid #fff";
		
		ad.onclick = function(){
			window.open( url );
		}
		
		return ad;
	}
	
	function setPos( ad,x ){
		var adwidth,adHeight;

		adwidth = Math.abs(document.documentElement.clientWidth-1002)/2;
		adHeight = Math.abs(document.documentElement.clientHeight);
		
		if( adHeight == 0 )
			adHeight = Math.abs(document.body.clientHeight);
			
		//alert( adHeight);
		
		ad.style.width = adwidth + "px";
		ad.style.height = adHeight + "px";
		
		if( x == undefined )
			ad.style.left = "-" + adwidth-2 + "px";
		else
			ad.style.left = x;
	}
	
	//重新计算
	function resize( ad1,ad2 ){
		var scroll_top = document.documentElement.scrollTop;
		var scroll_height = document.documentElement.scrollHeight;
		var div_height = ad1.clientHeight;
		
		if( scroll_top == 0 ){
			scroll_top = Math.abs(document.body.scrollTop);
			scroll_height = Math.abs(document.body.scrollHeight);
		}
		
		if( scroll_height == 0 || scroll_height <= scroll_height ){
			scroll_height = Math.abs(document.body.scrollHeight);
		}
		//alert( ",scroll_height:"+ Math.abs(document.body.scrollHeight) + ",scroll_top:" + scroll_top + ",div_height:" +div_height )
		if( scroll_height > (scroll_top+div_height) ){
			
			ad1.style.top = scroll_top + "px";
			ad2.style.top = scroll_top + "px";
			
			//alert(document.documentElement.clientWidth);
			setPos( ad1 );
			setPos( ad2,"1004px" );		
		}
	}
	
	this.init = function( adurl1,adurl2 ){
		ladurl = adurl1;
		radurl = adurl2;
		
		var adcontainer = getAdContainer();
		
		var ad1 = getAd( adurl1,"leftad" );
		var ad2 = getAd( adurl2,"rightad","1004px" );
		
		setAdContainer( adcontainer,ad1,ad2 );
		
		window.onscroll = function(){ resize( ad1,ad2 ); }
		window.onresize = function(){ resize( ad1,ad2 ); }
	}
}