var TIME_INTERVAL_TO_CHANGE_BANNER = 5*1000;	// 每多少秒用不同的 banner
var TOTAL_BANNERS = banners.length-1;
var iCURRENT_BANNER_INDEX = 0;
var imgBanner = document.getElementById ("imgBanner");	// for FireFox
var oPhotoNO = document.getElementById ("oPhotoNO");
var oTotalPhotoNO = document.getElementById ("oTotalPhotoNO");
var divPhotoDate = document.getElementById ("divPhotoDate");
var divPhotoTitle = document.getElementById ("divPhotoTitle");

function RandomBanner ()
{
	var theDate = new Date ();
	var iIndex = (Math.floor(theDate.getTime()/TIME_INTERVAL_TO_CHANGE_BANNER)) % TOTAL_BANNERS;
	if (banners[iIndex] != null)
	{
		ChangeBannerTo (iIndex);
	}
}

function ChangeBannerTo (iIndex)
{
	if (iIndex <0 || iIndex>=(TOTAL_BANNERS))
	{
		return false;
	}

	iCURRENT_BANNER_INDEX = iIndex;
	imgBanner.src = banners[iIndex].imageURI;
	//imgBanner.title = banners[iIndex].date + "\n\n" + banners[iIndex].title + "\n\n";
	imgBanner.alt = imgBanner.title = "第 " + (iIndex+1) + " 张，共 " + TOTAL_BANNERS + " 张 \n\n" + banners[iIndex].date + "\n\n" + banners[iIndex].title;

	oPhotoNO.innerHTML = (iIndex+1);
	oTotalPhotoNO.innerHTML = TOTAL_BANNERS;
	divPhotoDate.innerHTML = banners[iIndex].date;
	divPhotoTitle.innerHTML = banners[iIndex].title;
}
function BannerGotoBegin ()
{
	ChangeBannerTo (0); 
}
function BannerGotoEnd ()
{
	ChangeBannerTo (TOTAL_BANNERS-1); 
}
function BannerGotoNext ()
{
	iCURRENT_BANNER_INDEX ++;
	iCURRENT_BANNER_INDEX %= TOTAL_BANNERS;

	ChangeBannerTo (iCURRENT_BANNER_INDEX); 
}
function BannerGotoPrevious ()
{
	iCURRENT_BANNER_INDEX --;
	if (iCURRENT_BANNER_INDEX < 0)
	{
		iCURRENT_BANNER_INDEX = TOTAL_BANNERS - 1;
	}

	ChangeBannerTo (iCURRENT_BANNER_INDEX); 
}



// 显示 banner 列表
function ListBanners (container)
{
	if (container == null) return false;

	var i = 0;
	var arrayBannerList = new Array ();	//(banners.length);
	
	arrayBannerList.push ("<div style='height:480px; overflow-y:scroll; overflow:scroll; font-size:12px;'><ul style='margin-left:0px;'>");
	//for (i=0; i<TOTAL_BANNERS; i++)	// 顺序: 最先的排在最前
	for (i=TOTAL_BANNERS-1; i>=0; i--)	// 倒序: 最新的排在最前
	{
		arrayBannerList.push (
			"<li><a href='#' onclick='ChangeBannerTo(" + i + ");return false;'>" + 
			banners[i].date + ":" + banners[i].title + 
			"</a></li>");
	}
	arrayBannerList.push ("</ul></div>");
	container.innerHTML = arrayBannerList.join("");
}