//------------------------------------------------------------------------------
//  JavaScript functions for navigation-related roll-overs.
//
//  Irv.Elshoff@wldelft.nl
//  6 oct 03
//------------------------------------------------------------------------------


var navImgDir = '/lib/im/nav';

var navAgent = window.navigator.userAgent;
var navVers = parseInt (navAgent.charAt (navAgent.indexOf ("/")+1), 10);
var navNS = false;
var navIE = false;

var Buttons = new Object ();
var Nav_preloaded = false;

if (navigator.appName == 'Netscape') {
    navNS = true;
    }
else if (navigator.appName == 'Microsoft Internet Explorer') {
    navIE = true;
    }


//----	Function to create an initialize a single navigation button

function Nav_Button (level, name, sufoff, sufhigh, sufon, ext) {
    var filepath = name.replace (/_/g, '/');
    var imghi = navImgDir + '/' + filepath + sufhigh + ext;

    //	Determine whether the non-highlighted image is "on" or "off"
    //	It is "on" if all of the nav levels correspond to the name argument
    
    var navname = navL1;
    if (level >= 2 && navL2 != '')  navname += '_' + navL2;
    if (level >= 3 && navL3 != '')  navname += '_' + navL3;

    if (navname == name)
	var imglo = navImgDir + '/' + filepath + sufon  + ext;
    else
	var imglo = navImgDir + '/' + filepath + sufoff  + ext;

    Rov_New ('nav_' + name, imglo, imghi);
    }


//----	Roll-over functions

function Rov_New (name, imglo, imghi) {
    Buttons[name] = new Object ();

    Buttons[name].img = 'document.getElementsByName ("' + name + '")[0].src';
    Buttons[name].imglo = imglo;
    Buttons[name].imghi = imghi;

    eval (Buttons[name].img + '="' + Buttons[name].imglo + '"');

    var img = new Image ();
    img.src = imghi;
    }

function Rov_Show (name) {
    if (document.images && Nav_preloaded) {
	eval (Buttons[name].img + '="' + Buttons[name].imghi + '"');
	}
    }

function Rov_Hide (name) {
    if (document.images && Nav_preloaded) {
	eval (Buttons[name].img + '="' + Buttons[name].imglo + '"');
	}
    }