//上下无缝滚动
var speed = 20;
var direction = "top";
var tab = document.getelementbyid("scrollbox");
var tab1 = document.getelementbyid("scrollpic");
var tab2 = document.getelementbyid("scrollpic-copy");
var leftdir = document.getelementbyid("leftdir");
var rightdir = document.getelementbyid("rightdir");
tab2.innerhtml = tab1.innerhtml;
function marquee() {
    switch (direction) {
        case "top":
//            if (tab2.offsetheight - tab.scrolltop <= 0) {
//                tab.scrolltop -= tab1.offsetheight;
//            }
//            else {
                tab.scrolltop++;
//            }
            break;
        case "bottom":
//            if (tab.scrolltop <= 0) {
//                tab.scrolltop += tab2.offsetheight;
//            }
//            else {
                tab.scrolltop--;
//            }
            break;
    }
}
function changedirection(dir) {
    direction = dir;
}
var timer = setinterval(marquee, speed);
tab.onmouseover = function () { clearinterval(timer); };
tab.onmouseout = function () { timer = setinterval(marquee, speed); };
leftdir.onclick = function () { changedirection("top"); };
rightdir.onclick = function () { changedirection("bottom"); };