/*global define*/
define([
'./defined',
'./DeveloperError'
], function(
defined,
DeveloperError) {
'use strict';
/**
* A convenience object that simplifies the common pattern of attaching event listeners
* to several events, then removing all those listeners at once later, for example, in
* a destroy method.
*
* @alias EventHelper
* @constructor
*
*
* @example
* var helper = new Cesium.EventHelper();
*
* helper.add(someObject.event, listener1, this);
* helper.add(otherObject.event, listener2, this);
*
* // later...
* helper.removeAll();
*
* @see Event
*/
function EventHelper() {
this._removalFunctions = [];
}
/**
* Adds a listener to an event, and records the registration to be cleaned up later.
*
* @param {Event} event The event to attach to.
* @param {Function} listener The function to be executed when the event is raised.
* @param {Object} [scope] An optional object scope to serve as the <code>this</code>
* pointer in which the listener function will execute.
* @returns {EventHelper~RemoveCallback} A function that will remove this event listener when invoked.
*
* @see Event#addEventListener
*/
EventHelper.prototype.add = function(event, listener, scope) {
//>>includeStart('debug', pragmas.debug);
if (!defined(event)) {
throw new DeveloperError('event is required');
}
//>>includeEnd('debug');
var removalFunction = event.addEventListener(listener, scope);
this._removalFunctions.push(removalFunction);
var that = this;
return function() {
removalFunction();
var removalFunctions = that._removalFunctions;
removalFunctions.splice(removalFunctions.indexOf(removalFunction), 1);
};
};
/**
* Unregisters all previously added listeners.
*
* @see Event#removeEventListener
*/
EventHelper.prototype.removeAll = function() {
var removalFunctions = this._removalFunctions;
for (var i = 0, len = removalFunctions.length; i < len; ++i) {
removalFunctions[i]();
}
removalFunctions.length = 0;
};
/**
* A function that removes a listener.
* @callback EventHelper~RemoveCallback
*/
return EventHelper;
});