// JavaScript Document

// menuscript.js

//configuration variables
var timeout   = 250;   //milliseconds
var fadeSpeed = 500; //milliseconds
var useFade   = true; 

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

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

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

//MSIE has its own way of setting opacity, so we have to detect it
//all other major browsers support the DOM 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 menu using fad (if 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 interupted
	else if(lastOpacity[id] && (lastOpacity[id] < value)) value = lastOpacity[id];  //prevents flicker if multiple
	
	if(msie) e.style.filter = 'alpha(opacity=' + value * 100 + ')'; //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 timer
function fadeMenu (id)
{ 
	var start = 0;
	var end = 0;
	var s = Math.round( fadeSpeed / 25 ); 
	var timer = 0;
	var i;
	
	state[id] = false;
	 
	for( i = s; i >= 0 ; i-- ) {
		setTimeout ( "setOpacity('" + id + "'," + ( i/s ) + ")", timer++ * fadeSpeed / s)
	}
}