var preload;
var loadNav = {};

(function() {

	loadNav.setPreLoad = function(id, baseUrl, cngUrl) {
		if (!preload) preload = new Array();
		preload[id] = new Object();
		preload[id].baseUrl = baseUrl;
		preload[id].cngImg = new Image();
		preload[id].cngImg.src = cngUrl;
	};

	loadNav.setMousEvent = function(id, baseUrl, cngUrl) {
		// pre loading image.
		loadNav.setPreLoad(id, baseUrl, cngUrl);

		// Set window onload evens.
		addListener(window, "load", function() {
			var obj = document.getElementById(id);

			// Set mousover events.
			addListener(obj, "mouseover", function() {
				// Change target image url.
				var objImg = obj.getElementsByTagName("img");
				if (objImg.length == 1) {
					objImg[0].src = preload[id].cngImg.src;
				}
			}, false);

			// Set mousout events.
			addListener(obj, "mouseout", function() {
				// Change target image url.
				var objImg = obj.getElementsByTagName("img");
				if (objImg.length == 1) {
					objImg[0].src = preload[id].baseUrl;
				}
			}, false);

		}, false);
	};

	var addListener = function (el, eventType, fnc, cap) {
		if (el.addEventListener) {
			el.addEventListener(eventType, fnc, cap);
		} else if (el.attachEvent) {
			el.attachEvent("on" + eventType, fnc);
		}
	};

})();