var b_loaded = false;
var s_prefix = "menuitem_";
var s_path = "images/m_";
var s_menu = ["inicio", "hacienda", "agro", "pais", "clima", "archivo", "contacto"];
var s_ext = ".jpg";

function objId(id) {
	return document.getElementById(id);
}

function loadImage(uri) {
	var img = new Image();
	img.src = uri;
	return img;
}

function swapImages(i, state) {
	if (b_loaded == true)
		objId(s_prefix + i).src = state ? s_path + s_menu[i] + "_a" + s_ext :  s_path + s_menu[i] + s_ext;
}

function getIndex(id) {
	return id.substr(s_prefix.length);
}

function menuOver() {
	swapImages(getIndex(this.id), 1);
}

function menuOut() {
	swapImages(getIndex(this.id), 0);
}

function loadMenu(id) {
	var img, i;
	
	id--;
	if (document.images) {
		for (i=0; i<s_menu.length; i++)
			img = loadImage(s_path + s_menu[i] + "_a" + s_ext);
		b_loaded = true;
		for (i=0; i<s_menu.length; i++) {
			if (id != i) {
				objId(s_prefix + i).onmouseover = '';//menuOver;
				objId(s_prefix + i).onmouseout = '';//menuOut;
			} else
				objId(s_prefix + i).src = s_path + s_menu[i] + "_a" + s_ext;
		}
	}
}