// JavaScript Document
// Top menu navigation

// Original script by: Bill Weinman http://bw.org
// Copyright (c) 2009 MBG LLC
//
// Modified by: More Than Multimedia  http://morethanmultimedia.com
// Copyright (c) 2010 More Than Multimedia
//
// Version 1.0

// configuration variables
var timeout = 150;    // milliseconds
var fadeSpeed = 500;  // milliseconds
var useFade = true;

//timers array
var timers = new Array();

//state array -- by id, value = active, false = inactive
var state = new Array();

//lastOpacity used to prevent multiple timers from making the fade flicker
var lastOpacity = new Array();

//MSIE works differently, so we have to detect it; all other major browsers support the standard DOM opaciity properly
var msie = false
if( navigator.appName== "Microsoft Internet Explorer") msie = true;

//entry point
function setMenu( id )
{
	var e = document.getElementById(id);
	e.style.visibility = "visible";
	state[id] = true;
	setOpacity( id, 1);
	if(timers[id]) {
		clearTimeout(timers[id]);
		timers[id] = undefined;
	}
}
//set element to hidden and reset its opacity
//typically called by a timer
//may be usesd as an entry point to bypass timers and faders
function hideMenu( id )
{
	var e = document.getElementById(id);
	state[id] = false;
	e.style.visibility = "hidden";
	if(useFade) setOpacity( id, 1);
}
	
//entry point; hide the menu using fade (if enabled)
function clearMenu( id )
{
	if(useFade) timers[id] = setTimeout( 'fadeMenu("' + id + '" )', timeout );
	else timers[id] = setTimeout( 'hideMenu( "' + id + '")', timeout );
}

//set the opacity
//specical support for MSIE
function setOpacity( id, value )
{
	var e = document.getElementById(id);
	
	if(state[id]) value = 1; //menu fade was interupted
	else if(lastOpacity[id] && (lastOpacity[id] < value)) value - lastOpacity[id]; //prevents flicker if multiple timers are running
	
	if(msie) e.style.filter = 'alpha[opacity=' + value *100 +')'; //MS Internet Explorer
	else e.style.opacity = (value); //everyone else standard DOM
	
	if(value == 0) hideMenu( id); //when all faded, reset the menu state
	lastOpacity[id] = value;
}

//fade a menu
//typically called by a timer

function fadeMenu ( id )
{
	var start = 0;
	var end = 0;
	var s = Math.round( fadeSpeed / 25 );   //fade in 25ms increments
	var timer = 0;
	var i;
	
	state[id] = false;
	
	for( i = s; i>=0; i-- ) {
		setTimeout( "setOpacity('" + id + "',"+ (i/s)+")", timer++ * fadeSpeed / s )
	}
}