// JavaScript Document

//bw-menu.js
//simple dynamic menu
//
//by Bill Weiman http://bw.org/
//Copyright (c) 2009 BHG LLC
//
//VERSION 1.0.1
// 	Created for Dynamic Menus course at lynda.com
//

// configuration variables
var timeout =	250; // milliseconds  - ammount of time after curser leaves area before fade begins. this is 1/4 of a second
var fadeSpeed = 500;  // milliseconds - dudration of speed from beginning to completely fade away. this is 1/2 sec.
var useFade = 	true; // sets whether there will be a fade. if set to false there will be no fade.

//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 flickers
var lastOpacity = new Array();

// MSIE has its own way of setting opacity, so we have to detect it
// all the other major browsers support the standard COM opacity property
var msie = false;
if( navigator.appName == "Microsoft Internet Explorer" ) msie = true;

// entry point: set element to visible and clear its timers
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 used as an entry point to bypass timers and fades
function hideMenu( id )
{
	var e = document.getElementById(id);
	state[id] = false;
	e.style.visibility = "hidden";
	if(useFade) setOpacity( id, 1 );
}


// entry point: hide the meun using fade (iff enabled)
function clearMenu( id )
{
	if(useFade) timers[id] = setTimeout( 'fadeMenu("' + id + '")', timeout);
	else timers[id] = setTimeout( 'hideMenu( "' + id + '" )', timeout );
}

// set the opacity
//special support for MSIE
function setOpacity( id, value )
{
	var e = document.getElementById(id);
	
	if(state[id]) value = 1;   //menu fade was interrupted
	else if(lastOpacity[id] && (lastOpacity[id] < value)) value = lastOpacity[id];  // grevents flicker if multiple timeers
	
	if(msie) e.style.filter = 'alpha(opacity=' + value + 100 + ')';  //MS Internet Explorer and line 73 if n ot MSie
	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 25ths increments
	var timer = 0;
	var i;
	
	state[id] = false;
	
	for( i = s; i >= 0 ; i-- ) {
			setTimeout( "setOpacity( '" + id + "'," + ( i / s) + ")", timer++ * fadeSpeed / s )
		}
}