function next() {

    var control = getCurrent();

    if (control) {
        var current = parseInt(control.value);

        if (images.length > 0) {

            current = ((current + 1) % images.length);

            setItem(current)
            control.value = current;
        }
    }
}

function prev() {

    var control = getCurrent();

    if (control) {
        var current = parseInt(control.value);

        if (images.length > 0) {

            if (current == 0) {

                current = images.length - 1;
            }
            else {
                current -= 1;
            }

            setItem(current)
            control.value = current;
        }
    }
}

function getCurrent() { return document.getElementById('current'); }

function setItem(id) {

    var image = getImage();
    var current = getCurrent();

    if (image && current) {
        image.src = '/Tools/LoadObject.aspx?id=' + images[id];
        image.alt = alts[id];

        image.parentNode.href = url[id];

        current.value = id;
    }
}