Index: chrome/browser/resources/touch_ntp/eventtracker.js |
diff --git a/chrome/browser/resources/touch_ntp/eventtracker.js b/chrome/browser/resources/touch_ntp/eventtracker.js |
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+// Copyright (c) 2011 The Chromium Authors. All rights reserved. |
+// Use of this source code is governed by a BSD-style license that can be |
+// found in the LICENSE file. |
+ |
+/** @fileoverview |
arv (Not doing code reviews)
2011/03/10 19:25:59
@fileoverview EventTracker ...
Rick Byers
2011/03/11 02:44:33
Done.
|
+ * EventTracker is a simple class that manages the addition and removal of |
+ * DOM event listeners. In particular, it keeps track of all listeners that |
+ * have been added and makes it easy to remove some or all of them without |
+ * requiring all the information again. This is particularly handy when |
+ * the listener is a generated function such as a lambda or the result of |
+ * calling Function.bind. The goal of this class is to make it easier to |
+ * avoid memory leaks caused by DOM<->JS cycles - removing event listeners |
+ * breakes the DOM->JS part of the cycle. |
+ */ |
+ |
+/** @constructor |
+ * Create an EventTracker to track a set of events. |
arv (Not doing code reviews)
2011/03/10 19:25:59
/**
* Description
* @constructor
*/
Rick Byers
2011/03/11 02:44:33
Done.
|
+ * EventTracker instances are typically tied 1:1 with other objects or |
+ * DOM elements whose listeners should be removed when the object is disposed |
+ * or the corresponding elements are removed from the DOM. |
+ */ |
+function EventTracker() { |
+ /** |
+ * @type {Array.<EventTracker.Entry>} |
+ * @private |
+ */ |
+ this.listeners_ = []; |
+} |
+ |
+/** |
+ * The type of the internal tracking entry. |
+ * @typedef {{node: !Node, |
+ * eventType: string, |
+ * listener: Function, |
+ * capture: boolean}} |
+ */ |
+EventTracker.Entry; |
+ |
+/** |
+ * Add an event listener - replacement for Node.addEventListener. |
+ * @param {!Node} node The DOM node to add a listener to. |
+ * @param {string} eventType The type of event to subscribe to. |
+ * @param {Function} listener The listener to add. |
+ * @param {boolean} capture Whether to invoke during the capture phase. |
+ */ |
+EventTracker.prototype.add = function(node, eventType, listener, capture) |
arv (Not doing code reviews)
2011/03/10 19:25:59
Use the following syntax instead:
EventTracker.pr
Rick Byers
2011/03/11 02:44:33
I like it, thanks! Done. Does it not matter that
arv (Not doing code reviews)
2011/03/11 20:08:46
No. constructor is not reliable anyway.
function
|
+{ |
arv (Not doing code reviews)
2011/03/10 19:25:59
{ before new line
Rick Byers
2011/03/11 02:44:33
Done.
|
+ var h = {node: node, |
arv (Not doing code reviews)
2011/03/10 19:25:59
var h = {
eventType: ...
...
};
Rick Byers
2011/03/11 02:44:33
Done.
|
+ eventType: eventType, |
+ listener: listener, |
+ capture: capture}; |
+ this.listeners_.push(h); |
+ node.addEventListener(eventType, listener, capture); |
+}; |
+ |
+/** |
+ * Remove any specified event listeners added with this EventTracker. |
+ * @param {!Node} node The DOM node to remove a listener from. |
+ * @param {string} eventType The type of event to remove. |
+ */ |
+EventTracker.prototype.remove = function(node, eventType) |
+{ |
+ this.listeners_ = this.listeners_.filter(function(h) { |
+ if (h.node == node && h.eventType == eventType) { |
+ EventTracker.removeEventListener_(h); |
+ return false; |
+ } |
+ return true; |
+ }); |
+}; |
+ |
+/** |
+ * Remove all event listeners added with this EventTracker. |
+ */ |
+EventTracker.prototype.removeAll = function() |
+{ |
+ this.listeners_.forEach(EventTracker.removeEventListener_); |
+ this.listeners_ = []; |
+}; |
+ |
+/** |
+ * Remove a single event listener given it's tracker entry. It's up to the |
+ * caller to ensure the entry is removed from listeners_. |
+ * @param {EventTracker.Entry} h The entry describing the listener to remove. |
+ * @private |
Rick Byers
2011/03/11 02:44:33
Note that this is a static method (doesn't access
arv (Not doing code reviews)
2011/03/11 20:08:46
Yes, looks perfect
|
+ */ |
+EventTracker.removeEventListener_ = function(h) |
+{ |
+ h.node.removeEventListener(h.eventType, h.listener, h.capture); |
+}; |
+ |
+ |
arv (Not doing code reviews)
2011/03/10 19:25:59
remove empty lines
Rick Byers
2011/03/11 02:44:33
Done.
|
+ |
+ |
+ |