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// Copyright 2006 The Closure Library Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS-IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/**
* @fileoverview This event handler allows you to catch focusin and focusout
* events on descendants. Unlike the "focus" and "blur" events which do not
* propagate consistently, and therefore must be added to the element that is
* focused, this allows you to attach one listener to an ancester and you will
* be notified when the focus state changes of ony of its descendants.
* @author arv@google.com (Erik Arvidsson)
* @see ../demos/focushandler.html
*/
goog.provide('goog.events.FocusHandler');
goog.provide('goog.events.FocusHandler.EventType');
goog.require('goog.events');
goog.require('goog.events.BrowserEvent');
goog.require('goog.events.EventTarget');
goog.require('goog.userAgent');
/**
* This event handler allows you to catch focus events when descendants gain or
* loses focus.
* @param {Element|Document} element The node to listen on.
* @constructor
* @extends {goog.events.EventTarget}
*/
goog.events.FocusHandler = function(element) {
goog.events.EventTarget.call(this);
/**
* This is the element that we will listen to the real focus events on.
* @type {Element|Document}
* @private
*/
this.element_ = element;
// In IE we use focusin/focusout and in other browsers we use a capturing
// listner for focus/blur
var typeIn = goog.userAgent.IE ? 'focusin' : 'focus';
var typeOut = goog.userAgent.IE ? 'focusout' : 'blur';
/**
* Store the listen key so it easier to unlisten in dispose.
* @private
* @type {number}
*/
this.listenKeyIn_ = (/** @type {number} */
goog.events.listen(this.element_, typeIn, this, !goog.userAgent.IE));
/**
* Store the listen key so it easier to unlisten in dispose.
* @private
* @type {number}
*/
this.listenKeyOut_ = (/** @type {number} */
goog.events.listen(this.element_, typeOut, this, !goog.userAgent.IE));
};
goog.inherits(goog.events.FocusHandler, goog.events.EventTarget);
/**
* Enum type for the events fired by the focus handler
* @enum {string}
*/
goog.events.FocusHandler.EventType = {
FOCUSIN: 'focusin',
FOCUSOUT: 'focusout'
};
/**
* This handles the underlying events and dispatches a new event.
* @param {goog.events.BrowserEvent} e The underlying browser event.
*/
goog.events.FocusHandler.prototype.handleEvent = function(e) {
var be = e.getBrowserEvent();
var event = new goog.events.BrowserEvent(be);
event.type = e.type == 'focusin' || e.type == 'focus' ?
goog.events.FocusHandler.EventType.FOCUSIN :
goog.events.FocusHandler.EventType.FOCUSOUT;
this.dispatchEvent(event);
};
/** @override */
goog.events.FocusHandler.prototype.disposeInternal = function() {
goog.events.FocusHandler.superClass_.disposeInternal.call(this);
goog.events.unlistenByKey(this.listenKeyIn_);
goog.events.unlistenByKey(this.listenKeyOut_);
delete this.element_;
};
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