//主页左上角焦点图特效
var rollCount;
var rollPeriod = 2000;
var isStart = true;
var nn = 1;
var tt = false;
function change_img() {
    if (isStart) {
        if (nn > rollCount) {
            nn = 1;
        }
        setFocus(nn);
    } else {
        tt = setTimeout('change_img()', 1000);
    }
}
function setFocus(i) {
    if (tt) {
        clearTimeout(tt);
    }
    selectLayer1(i);
    nn = parseInt(i) + 1;
    tt = setTimeout('change_img()', rollPeriod);
}
function selectLayer1(i) {
    for (var j = 1; j <= rollCount; j++) {
        if (document.getElementById("focus" + j) && document.getElementById("change" + j)) {
            if (j == i) {
                document.getElementById("focus" + j).style.display = "block";
                document.getElementById("change" + j).className = "current";
            } else {
                document.getElementById("focus" + j).style.display = "none";
                document.getElementById("change" + j).className = "";
            }
        }
    }
}