var HighlightImagePrefix="highlight_";

var AreaTypeIDs=new Array("B","NRM","LGA");

function getHighlightImagePath(areaID) {
	return getImagesDirectory()+"/"+HighlightImagePrefix+areaID+".gif";
}

function isValidAreaTypeID(areaTypeID) {
	for (i=0; i<AreaTypeIDs.length; i++) {
		var validAreaTypeID=AreaTypeIDs[i];
		if (areaTypeID==validAreaTypeID) return true;
	}
	return false;
}

function getInitialAreaType() {
	// first check whether a radio button is already set, which is the case in some browsers when the back button was used.
	for (var i=0; i<AreaTypeIDs.length; i++) {
		var areaTypeID=AreaTypeIDs[i];
		var areaTypeRadioButton=document.getElementById("AreaType_"+areaTypeID);
		if (areaTypeRadioButton.checked) return areaTypeRadioButton.value;
	}
	// otherwise use the value supplied in the query string
	return getQueryStringValue("AreaTypeID");
}

function setAreaTypeIDBase(areaTypeID) {
	if (!isValidAreaTypeID(areaTypeID)) areaTypeID="B";
	if (areaTypeID==AreaTypeID) return null;
	AreaTypeID=areaTypeID;
	document.getElementById("AreaType_"+areaTypeID).checked=true;
	MapImage.src=getImagesDirectory()+"/state_"+areaTypeID+".jpg";
	OverlayImage.useMap="#Map_"+areaTypeID;
	refresh();
	return AreaTypeID;
}

function setMapMessage(areaID) {
	var mapElement=document.getElementById(areaID);
	MapMessage.firstChild.nodeValue=mapElement.alt;
}

function clearMapMessage(areaID) {
	MapMessage.firstChild.nodeValue=" ";
}