function toggle(div_id) {
    var el = document.getElementById(div_id);
    if (el.style.display == 'none') { el.style.display = 'block'; }
    else { el.style.display = 'none'; }
}
function blanket_size(popUpDivVar) {
    if (typeof window.innerWidth != 'undefined') {
        viewportheight = window.innerHeight;
    } else {
        viewportheight = document.documentElement.clientHeight;
    }
    if ((viewportheight > document.body.parentNode.scrollHeight) && (viewportheight > document.body.parentNode.clientHeight)) {
        blanket_height = viewportheight;
    } else {
        if (document.body.parentNode.clientHeight > document.body.parentNode.scrollHeight) {
            blanket_height = document.body.parentNode.clientHeight;
        } else {
            blanket_height = document.body.parentNode.scrollHeight;
        }
    }
    var blanket = document.getElementById('blanket');
    blanket.style.height = blanket_height + 'px';
    var popUpDiv = document.getElementById(popUpDivVar);
    popUpDiv_height = blanket_height / 2 - 150; //150 is half popup's height
    popUpDiv.style.top = popUpDiv_height + 'px';
}
function window_pos(popUpDivVar) {
    if (typeof window.innerWidth != 'undefined') {
        viewportwidth = window.innerHeight;
    } else {
        viewportwidth = document.documentElement.clientHeight;
    }
    if ((viewportwidth > document.body.parentNode.scrollWidth) && (viewportwidth > document.body.parentNode.clientWidth)) {
        window_width = viewportwidth;
    } else {
        if (document.body.parentNode.clientWidth > document.body.parentNode.scrollWidth) {
            window_width = document.body.parentNode.clientWidth;
        } else {
            window_width = document.body.parentNode.scrollWidth;
        }
    }
    var popUpDiv = document.getElementById(popUpDivVar);
    window_width = window_width / 2 - 150; //150 is half popup's width
    popUpDiv.style.left = window_width + 'px';
}
function popup(windowname) {
    blanket_size(windowname);
    window_pos(windowname);
    toggle('blanket');
    toggle(windowname);
}

var DDSPEED = 8;
var DDTIMER = 25;

// main function to handle the mouse events //
function ddMenu(id, d) {
    var h = document.getElementById(id + '-ddheader');
    var c = document.getElementById(id + '-ddcontent');
    clearInterval(c.timer);
    if (d == 1) {
        clearTimeout(h.timer);
        if (c.maxh && c.maxh <= c.offsetHeight) { return }
        else if (!c.maxh) {
            c.style.display = 'block';
            c.style.height = 'auto';
            c.maxh = c.offsetHeight;
            c.style.height = '0px';
        }
        c.timer = setInterval(function() { ddSlide(c, 1) }, DDTIMER);
    } else {
        h.timer = setTimeout(function() { ddCollapse(c) }, 50);
    }
}

// main function to handle the mouse events //
function ddMenup(id, d) {
    var h = document.getElementById(id + '-ddheader');
    var c = document.getElementById(id + '-ddcontent');
    clearInterval(c.timer);
    if (d == 1) {
        clearTimeout(h.timer);
        if (c.maxh && c.maxh <= c.offsetHeight) { return }
        else if (!c.maxh) {
            c.style.top = '-' + c.offsetHeight + 'px';
            c.style.display = 'block';
            c.style.height = 'auto';
            c.maxh = c.offsetHeight;
            c.style.height = '0px';
        }
        c.timer = setInterval(function() { ddSlideup(c, 1) }, DDTIMER);
    } else {
        h.timer = setTimeout(function() { ddCollapseup(c) }, 50);
    }
}

// collapse the menu //
function ddCollapse(c) {
    c.timer = setInterval(function() { ddSlide(c, -1) }, DDTIMER);
}

// collapse the menu //
function ddCollapseup(c) {
    c.timer = setInterval(function() { ddSlideup(c, -1) }, DDTIMER);
}

// cancel the collapse if a user rolls over the dropdown //
function cancelHide(id) {
    var h = document.getElementById(id + '-ddheader');
    var c = document.getElementById(id + '-ddcontent');
    clearTimeout(h.timer);
    clearInterval(c.timer);
    if (c.offsetHeight < c.maxh) {
        c.timer = setInterval(function() { ddSlide(c, 1) }, DDTIMER);
    }
}

// incrementally expand/contract the dropdown and change the opacity //
function ddSlide(c, d) {
    var currh = c.offsetHeight;
    var dist;
    if (d == 1) {
        dist = (Math.round((c.maxh - currh) / DDSPEED));
    } else {
        dist = (Math.round(currh / DDSPEED));
    }
    if (dist <= 1 && d == 1) {
        dist = 1;
    }
    c.style.height = currh + (dist * d) + 'px';
    c.style.opacity = currh / c.maxh;
    c.style.filter = 'alpha(opacity=' + (currh * 100 / c.maxh) + ')';
    if ((currh < 2 && d != 1) || (currh > (c.maxh - 2) && d == 1)) {
        clearInterval(c.timer);
    }
}

// incrementally expand/contract the dropdown and change the opacity //
function ddSlideup(c, d) {
    var currh = c.offsetHeight;
    var dist;
    if (d == 1) {
        dist = (Math.round((c.maxh - currh) / DDSPEED));
    } else {
        dist = (Math.round(currh / DDSPEED));
    }
    if (dist <= 1 && d == 1) {
        dist = 1;
    }
    c.style.top = parseInt(c.style.top.replace('px', '')) - parseInt(dist * d) + 'px';
    c.style.height = currh + (dist * d) + 'px';
    c.style.opacity = currh / c.maxh;
    c.style.filter = 'alpha(opacity=' + (currh * 100 / c.maxh) + ')';
    if ((currh < 2 && d != 1) || (currh > (c.maxh - 2) && d == 1)) {
        clearInterval(c.timer);
    }
}