function bannerImage(name,nextBanner,prevBanner)
{
	this.name = name;
	this.targetUrl = '';
	this.nextBanner = nextBanner;
	this.prevBanner = prevBanner;
	
	this.baseImage = null;
	this.leftArrow = null; //image to use for left arrow when this banner is the previous item
	this.rightArrow = null; //image to use for left arrow when this banner is the previous item
	
	this.loadBaseImage=loadBaseImage;
	this.loadLeftArrowImage = loadLeftArrowImage;
	this.loadRightArrowImage = loadRightArrowImage;
}

function loadBaseImage(url,h,w)
{
	this.baseImage = new Image(h,w);
	this.baseImage.src = url;
}

function loadLeftArrowImage(url,h,w)
{
	this.leftArrow = new Image(h,w);
	this.leftArrow.src = url;
}

function loadRightArrowImage(url,h,w)
{
	this.rightArrow = new Image(h,w);
	this.rightArrow.src = url;
}


function bannerList()
{
	this.banners = new Array();
	this.currentBanner = '';
	
	this.getBanner = getBanner;
	this.showBanner = showBanner;	
	this.nextBannerName = nextBannerName;
	this.prevBannerName = prevBannerName;
	this.addBanner = addBanner;
}

function addBanner(b)
{
	this.banners.push(b);
}

function getBanner(bannerName)
{
  if(this.banners.length>0)
  {
  	for(var x=0;x<this.banners.length;x++)
  	{
  		if(this.banners[x].name==bannerName)
  		{
  			return this.banners[x];
  		}
  	}
  }
  return null;
}

function showBanner(bannerName,leftArrow,baseImg,rightArrow)
{
	var objBanner = this.getBanner(bannerName)
	
	if(objBanner)
	{
		var objNextBanner = this.getBanner(objBanner.nextBanner);
		var objPrevBanner = this.getBanner(objBanner.prevBanner);
		
		if(objPrevBanner)
		{
			leftArrow.src = objPrevBanner.leftArrow.src
			showElement(leftArrow);
		}
		else
			hideElement(leftArrow);
		
		if(objNextBanner)
		{
			rightArrow.src = objNextBanner.rightArrow.src;
			showElement(rightArrow);
		}
		else
			hideElement(rightArrow);	
		
		baseImg.src = objBanner.baseImage.src;
		showElement(baseImg);
		this.currentBanner = bannerName;
	}	
}

function nextBannerName()
{
	if(this.currentBanner.length>0)
	{
		b = this.getBanner(this.currentBanner);
		if(b)
		{
			return b.nextBanner;
		}
	}
	return '';
}

function prevBannerName()
{
	if(this.currentBanner.length>0)
	{
		b = this.getBanner(this.currentBanner);
		if(b)
		{
			return b.prevBanner;
		}
	}
	return '';
}