// Dropdown menu control

function Dropdown(activatorId, dropdownId) {

	// store activator and dropdown elements
	this.activator = document.getElementById(activatorId);
	this.dropdown = document.getElementById(dropdownId);
	this.activatorImage = document.getElementById(activatorId + "Image");

	// wire up show/hide events
	registerEventHandler(this.activator,'mouseover', getInstanceDelegate(this, "show"));
	registerEventHandler(this.activator,'mouseout', getInstanceDelegate(this, "requestHide"));
	registerEventHandler(this.dropdown,'mouseover', getInstanceDelegate(this, "show"));
	registerEventHandler(this.dropdown,'mouseout', getInstanceDelegate(this, "requestHide"));

	// fix visibility and position
	this.dropdown.style.visibility = 'hidden';
	this.dropdown.style.position = 'absolute';
	this.reposition(null);

	// wire up repositioning event
	registerEventHandler(window, 'resize', getInstanceDelegate(this, "reposition"));


}

Dropdown.prototype.show = function(e) {
	clearTimeout(this.timer);
	this.dropdown.style.visibility = 'visible';
	if (this.activatorImage != null)
		this.activatorImage.src = dropDownHoverImage.src;
	if (this.activator != null)
		this.activator.className = "filterOnHover";
}

Dropdown.prototype.hide = function(e) {
	this.dropdown.style.visibility = 'hidden';
	if (this.activatorImage != null)
		this.activatorImage.src = dropDownImage.src;
	if (this.activator != null)
		this.activator.className = "filter";
}

Dropdown.prototype.requestHide = function(e) {
	this.timer = setTimeout( getInstanceDelegate(this, "hide"), 250);
}

Dropdown.prototype.reposition = function(e) {

	// get position of activator
	var offsetLeft = 0;
	var offsetTop = 0;
	var offsetElement = this.activator;

	while (offsetElement) {
		offsetLeft += offsetElement.offsetLeft;
		offsetTop += offsetElement.offsetTop;
		offsetElement = offsetElement.offsetParent;
}

	// set position of dropdown relative to it
	this.dropdown.style.left = offsetLeft;
	this.dropdown.style.top = offsetTop + this.activator.offsetHeight;
}

Dropdown.prototype.SetActivatorLabel = function(labelId)
{
	// get the children of the activator node, which includes the label nodes
	var labelNodes = this.activator.children;


	for(var labelCount=0; labelCount < labelNodes.length; labelCount++)
	{
		if(labelNodes[labelCount].tagName == 'LABEL')
		{
			var labelNodeId = labelNodes[labelCount].getAttribute('id');
			if (labelNodeId == labelId)
			{
				labelNodes[labelCount].style.display = "inline";
		}
			else
			{
				labelNodes[labelCount].style.display = "none";
		}
	}
}
}