// JavaScript Document

//config vars
var timeout = 250; //millisecs
var fadeSpeed = 500; //millisecs
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 mak,ing the fade flicker
var lastOpacity = new Array();

//IE has its own way of setting opacity, so we have to detect it
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(userFade) 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
// special support for IE
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];  ///prevents flicker if multiple timers
	
	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)
	}
}