var counts=4;

var nn;
var tt;
var bPlay=new Image;
bPlay.src = "http://makewing.com/lanren/js/18/images/bu_pla.gif";
var bPause=new Image;
bPause.src = "http://makewing.com/lanren/js/18/images/bu_pau.gif";
nn=1;
setTimeout('change_img()',4000);
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 == "http://makewing.com/lanren/js/18/images/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=counts;
    setFocus(nn);
}
function next_img(){
    resetPlay();
    nn++;
    if(nn > counts) nn=1;
    setFocus(nn);
}
function change_img()
{
        nn++;
        if(nn>counts) nn=1;
        setFocus(nn);
}
function setFocus(i)
{
    if(tt) clearTimeout(tt);
    nn = i;
    selectLayer1(i);
    tt=setTimeout('change_img()',4000);
}
function selectLayer1(i)
{
    document.getElementById("ns1").className="banner03";
    document.getElementById("ns2").className="banner03";
    document.getElementById("ns3").className="banner03";
    document.getElementById("ns4").className="banner03";
    switch(i)
    {
        case 1:
            document.getElementById("imgUrl").href = "http://www.3y360.com/ymt/Ymtxc.aspx";
            document.getElementById("nowImg").src = "images/01.jpg";
            document.getElementById("ns1").className="banner02";
         break;
        case 2:
            document.getElementById("imgUrl").href = "http://www.kuaituzi.com/";
            document.getElementById("nowImg").src = "images/02.jpg";
            document.getElementById("ns2").className="banner02";
         break;
         case 3:
            document.getElementById("imgUrl").href = "#";
            document.getElementById("nowImg").src = "images/03.jpg";
            document.getElementById("ns3").className="banner02";
         break;
         case 4:
            document.getElementById("imgUrl").href = "#";
            document.getElementById("nowImg").src = "images/04.jpg";
            document.getElementById("ns4").className="banner02";
         break;
    }
}