var isStart=true;
var nn;
var tt;
var nnCount = 2;
var bPlay = new Image;
bPlay.src = "/images/bu_pla.gif";
var bPause=new Image;
bPause.src = "/images/bu_pau.gif";

nn=1;
setTimeout('change_img()',400000000);

function resetPlay()
{
	isStart=true;
	var e = document.getElementById("top_slider");
	var a = e.getElementsByTagName("img");
	for (i=0; i<a.length;i++)
	{
		if(a[i].src == bPlay.src) a[i].src = bPause.src;
	}
}

function playorpau(e)
{
	if(e.src == "bu_pau.gif")
	{
		e.src = bPlay.src ;
		isStart = false;
	}
	else
	{
		e.src = bPause.src;
		isStart = true;
	}
}

function pre_img()
{
	resetPlay();
	nn--;
	if (nn < 1)
	{
		nn = nnCount;
	}
	setFocus(nn);
}

function next_img()
{
	resetPlay();
	nn++;
	if (nn > nnCount)
	{
		nn=1;
	}
	setFocus(nn);
}

function change_img()
{
	if (isStart)
	{
 		nn++;
 		if(nn>nnCount)
 		{
 			nn=1;
 		}
 		setFocus(nn);
 	}
 	else
 	{
 		tt=setTimeout('change_img()',100);
 	}
}

function setFocus(i)
{
	if (tt)
	{
		clearTimeout(tt);
	}
 	nn = i;
 	selectLayer(i);
 	tt=setTimeout('change_img()', 400000000);
}

function selectLayer(current)
{
	var bbsCount = 0;
	var m = document.getElementById("top_slider").childNodes;

	for (var i=0; i < m.length; i++)
	{
		if (m[i].nodeType == 1 && m[i].id.indexOf("bbs_s") == 0)
		{
			bbsCount++;
		}
	}

	for (var j = 1; j <= bbsCount; j++)
	{
        var menuId = "bbs_s" + j;
        document.getElementById(menuId).style.display=j==current?"block":"none";
    }
}