1
// Copyright 2006 The Closure Library Authors. All Rights Reserved.
2
//
3
// Licensed under the Apache License, Version 2.0 (the "License");
4
// you may not use this file except in compliance with the License.
5
// You may obtain a copy of the License at
6
//
7
//      http://www.apache.org/licenses/LICENSE-2.0
8
//
9
// Unless required by applicable law or agreed to in writing, software
10
// distributed under the License is distributed on an "AS-IS" BASIS,
11
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12
// See the License for the specific language governing permissions and
13
// limitations under the License.
14

15
/**
16
 * @fileoverview This event handler allows you to catch focusin and focusout
17
 * events on  descendants. Unlike the "focus" and "blur" events which do not
18
 * propagate consistently, and therefore must be added to the element that is
19
 * focused, this allows you to attach one listener to an ancester and you will
20
 * be notified when the focus state changes of ony of its descendants.
21
 * @author [email protected] (Erik Arvidsson)
22
 * @see ../demos/focushandler.html
23
 */
24

25
goog.provide('goog.events.FocusHandler');
26
goog.provide('goog.events.FocusHandler.EventType');
27

28
goog.require('goog.events');
29
goog.require('goog.events.BrowserEvent');
30
goog.require('goog.events.EventTarget');
31
goog.require('goog.userAgent');
32

33

34

35
/**
36
 * This event handler allows you to catch focus events when descendants gain or
37
 * loses focus.
38
 * @param {Element|Document} element  The node to listen on.
39
 * @constructor
40
 * @extends {goog.events.EventTarget}
41
 * @final
42
 */
43
goog.events.FocusHandler = function(element) {
44
  goog.events.EventTarget.call(this);
45

46
  /**
47
   * This is the element that we will listen to the real focus events on.
48
   * @type {Element|Document}
49
   * @private
50
   */
51
  this.element_ = element;
52

53
  // In IE we use focusin/focusout and in other browsers we use a capturing
54
  // listner for focus/blur
55
  var typeIn = goog.userAgent.IE ? 'focusin' : 'focus';
56
  var typeOut = goog.userAgent.IE ? 'focusout' : 'blur';
57

58
  /**
59
   * Store the listen key so it easier to unlisten in dispose.
60
   * @private
61
   * @type {goog.events.Key}
62
   */
63
  this.listenKeyIn_ =
64
      goog.events.listen(this.element_, typeIn, this, !goog.userAgent.IE);
65

66
  /**
67
   * Store the listen key so it easier to unlisten in dispose.
68
   * @private
69
   * @type {goog.events.Key}
70
   */
71
  this.listenKeyOut_ =
72
      goog.events.listen(this.element_, typeOut, this, !goog.userAgent.IE);
73
};
74
goog.inherits(goog.events.FocusHandler, goog.events.EventTarget);
75

76

77
/**
78
 * Enum type for the events fired by the focus handler
79
 * @enum {string}
80
 */
81
goog.events.FocusHandler.EventType = {
82
  FOCUSIN: 'focusin',
83
  FOCUSOUT: 'focusout'
84
};
85

86

87
/**
88
 * This handles the underlying events and dispatches a new event.
89
 * @param {goog.events.BrowserEvent} e  The underlying browser event.
90
 */
91
goog.events.FocusHandler.prototype.handleEvent = function(e) {
92
  var be = e.getBrowserEvent();
93
  var event = new goog.events.BrowserEvent(be);
94
  event.type = e.type == 'focusin' || e.type == 'focus' ?
95
      goog.events.FocusHandler.EventType.FOCUSIN :
96
      goog.events.FocusHandler.EventType.FOCUSOUT;
97
  this.dispatchEvent(event);
98
};
99

100

101
/** @override */
102
goog.events.FocusHandler.prototype.disposeInternal = function() {
103
  goog.events.FocusHandler.superClass_.disposeInternal.call(this);
104
  goog.events.unlistenByKey(this.listenKeyIn_);
105
  goog.events.unlistenByKey(this.listenKeyOut_);
106
  delete this.element_;
107
};
108

109