/**
 * utilities.js
 * OneEarthOneMission
 * Utility functions
 * Modified by Min Huang 02/27/2004
 * Last modified by Jasmina Kent 07/21/05
 */



/**
 * getElementSafely(id)
 * Safely gets the element by id in all versions of NS and IE.  Also
 * sets element.css or element.style depending on the browser.  After
 * a call to this function you may reference the element's style 
 * properties with either element.css or element.style
 * @param id	The element you want to get by id
 * @return		Reference to the element you want
 */
function getElementSafely(id) {
  var element = (document.getElementById) ? document.getElementById(id) : 
				(document.all) ? document.all[id] :
				(document.layers) ? document.layers[id] : null;
  if (element)
	element.css = (element.style) ? element.style : element;
  return element;
}

/**
 * bookmark()
 * Allows user to bookmark the page.
 */
function bookmark(url, description)
{
	if (navigator.appName == "Microsoft Internet Explorer")
		window.external.AddFavorite(url, description);
	else if (navigator.appName == "Netscape")
		alert("Netscape users hit CTRL+D to bookmark.");
}

/**
 * clickme()
 * Dummy functions for links that serve only to trigger JavaScript
 * behavior, and do not actually go anywhere.
 */
function clickme() {
	return;
}

/**
 * detectBrowser()
 * Detects the user's browser.
 */
function detectBrowser() {
    if (document.all) {
        IE = true;
    } else if (document.getElementById) {
        NS7 = true;
    } else if (document.layers) {
        NS4 = true;
    }
}

function setInitialBackgroundImage(imagePrefix, imageExt) {
	var imageFileName;
	if(screen.width<=800)
    imageFileName="images/"+imagePrefix+"background_a."+imageExt;
  else
    imageFileName="images/"+imagePrefix+"background."+imageExt;
	var cssVar = "url("+imageFileName+")";
	getElementSafely("indexBody").css.backgroundImage=cssVar;
}

function setBackgroundImage(imagePrefix, imageExt) {
	var currentBackground=getElementSafely("indexBody").css.backgroundImage;
  var imageFileName;
  if(screen.width<=800)
    imageFileName="images/"+imagePrefix+"background_a."+imageExt;
  else
    imageFileName="images/"+imagePrefix+"background."+imageExt;
	var cssVar = "url("+imageFileName+")";
	if(currentBackground!=cssVar) {		
		getElementSafely("indexBody").css.backgroundImage=cssVar;
	}
}

var IE;
var NS4;
var NS7;
detectBrowser();