// declare variable for setting smoothness of slide (-5 for smoother)
var timerlen = 5;

// declare variable for setting the slide length (in miliseconds)
var slideAniLen = 500;

// declare arrays for using in functions below
var timerID = new Array();
var startTime = new Array();
var obj = new Array();
var endHeight = new Array();
var moving = new Array();
var dir = new Array();

// determines whether to start sliding down the div or not
function slidedown(objname) {
	if(moving[objname])
		return;

	if(document.getElementById(objname).style.display != "none")
		return; // cannot slide down something that is already visible
		
	moving[objname] = true;
	dir[objname] = "down";
	startslide(objname);
}

// determines whether to start sliding up the div or not
function slideup(objname) {
	if(moving[objname])
		return;

	if(document.getElementById(objname).style.display == "none")
		return; // cannot slide up something that is already hidden

	moving[objname] = true;
	dir[objname] = "up";
	startslide(objname);
}

function startslide(objname) {
	obj[objname] = document.getElementById(objname);

	if(dir[objname] == "down") {
		obj[objname].style.height = "1px";
	}

	obj[objname].style.display = "block";
	startTime[objname] = (new Date()).getTime();
	endHeight[objname] = obj[objname].scrollHeight;

	timerID[objname] = setInterval('slidetick(\'' + objname + '\');',timerlen);
}

// create the animation effect
function slidetick(objname) {
	var elapsed = (new Date()).getTime() - startTime[objname];
 
	if (elapsed > slideAniLen)
		endSlide(objname)
	else {
		var d =Math.round(elapsed / slideAniLen * endHeight[objname]);
		
		if(dir[objname] == "up")
			d = endHeight[objname] - d;
			
		obj[objname].style.height = d + "px";
	}
	
	return;
}

// end animation when arrived at bottom and clean up
function endSlide(objname) {
	clearInterval(timerID[objname]);
	
	if(dir[objname] == "up")
		obj[objname].style.display = "none";
		
	obj[objname].style.height = endHeight[objname] + "px";
 
	delete(moving[objname]);
	delete(timerID[objname]);
	delete(startTime[objname]);
	delete(endHeight[objname]);
	delete(obj[objname]);
	delete(dir[objname]);
	
	return;
}

function toggle(objname) {
	if(document.getElementById(objname).style.display == "none") {
		// div is hidden, so slide down
		slidedown(objname);
	}
	else {
		// div is not hidden, so slide up
		slideup(objname);
	}
}