// Written by Ahmad Azarinurazie (aien@pixl8.co.uk) for Browse by region template of IMW.
// Created on 16th of July 2008

// This will help to prefetch the necessary images
function prefetch() {
	var imageUrls = ["/graphics/map_hover_europe.gif", "/graphics/map_hover_america.gif", "/graphics/map_hover_africa.gif", "/graphics/map_hover_australasia.gif", "/graphics/map_hover_asia.gif"];
	var images = [];
	
	for(var i=0; i<imageUrls.length; i++) {
		var image = new Image();
		image.src = imageUrls[i];
		images.push(image);
	}
}

function swapRegion(map) {
	if (map) document.getElementById("region-map").src = "/graphics/map_hover_" + map + ".gif";
	else document.getElementById("region-map").src = "/graphics/map.gif";
}

// taken from http://dean.edwards.name/weblog/2005/10/add-event/
function addEvent(element, type, handler) {
  // assign each event handler a unique ID
  if (!handler.$$guid) handler.$$guid = addEvent.guid++;
  // create a hash table of event types for the element
  if (!element.events) element.events = {};
  // create a hash table of event handlers for each element/event pair
  var handlers = element.events[type];
  if (!handlers) {
    handlers = element.events[type] = {};
    // store the existing event handler (if there is one)
    if (element["on" + type]) {
      handlers[0] = element["on" + type];
    }
  }
  // store the event handler in the hash table
  handlers[handler.$$guid] = handler;
  // assign a global event handler to do all the work
  element["on" + type] = handleEvent;
};
// a counter used to create unique IDs
addEvent.guid = 1;

function removeEvent(element, type, handler) {
  // delete the event handler from the hash table
  if (element.events && element.events[type]) {
    delete element.events[type][handler.$$guid];
  }
};

function handleEvent(event) {
  // grab the event object (IE uses a global event object)
  event = event || window.event;
  // get a reference to the hash table of event handlers
  var handlers = this.events[event.type];
  // execute each event handler
  for (var i in handlers) {
    this.$$handleEvent = handlers[i];
    this.$$handleEvent(event);
  }
};

addEvent(window, 'load', prefetch);