var DDSPEED = 1;
var DDTIMER = 1;

// main function to handle the mouse events //
function ddMenu(id, d, pos) {
	var h = document.getElementById(id + '-header');
	var c = document.getElementById(id + '-sub');
	var n = document.getElementById('nav');
	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);		
		if(pos != undefined) {
			var w = document.getElementById('header').clientWidth;
			if(w > 1024) { w = Math.round((w - 1024)/2); } else { w = 0; }
			c.style.left = (w + pos) + 'px';
		}		
	} else { h.timer = setTimeout(function(){ddCollapse(c)},50); }
}

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

// cancel the collapse if a user rolls over the dropdown //
function cancelHide(id) {
	var h = document.getElementById(id + '-header');
	var c = document.getElementById(id + '-sub');
	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); }
}