| // Copyright 2013 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 monitor wraps the Page Visibility API. |
| * @see http://www.w3.org/TR/page-visibility/ |
| */ |
| |
| goog.provide('goog.labs.dom.PageVisibilityEvent'); |
| goog.provide('goog.labs.dom.PageVisibilityMonitor'); |
| goog.provide('goog.labs.dom.PageVisibilityState'); |
| |
| goog.require('goog.dom'); |
| goog.require('goog.dom.vendor'); |
| goog.require('goog.events'); |
| goog.require('goog.events.Event'); |
| goog.require('goog.events.EventTarget'); |
| goog.require('goog.events.EventType'); |
| goog.require('goog.memoize'); |
| |
| goog.scope(function() { |
| var dom = goog.labs.dom; |
| |
| |
| /** |
| * The different visibility states. |
| * @enum {string} |
| */ |
| dom.PageVisibilityState = { |
| HIDDEN: 'hidden', |
| VISIBLE: 'visible', |
| PRERENDER: 'prerender', |
| UNLOADED: 'unloaded' |
| }; |
| |
| |
| |
| /** |
| * This event handler allows you to catch page visibility change events. |
| * @param {!goog.dom.DomHelper=} opt_domHelper |
| * @constructor |
| * @extends {goog.events.EventTarget} |
| * @final |
| */ |
| dom.PageVisibilityMonitor = function(opt_domHelper) { |
| dom.PageVisibilityMonitor.base(this, 'constructor'); |
| |
| /** |
| * @private {!goog.dom.DomHelper} |
| */ |
| this.domHelper_ = opt_domHelper || goog.dom.getDomHelper(); |
| |
| /** |
| * @private {?string} |
| */ |
| this.eventType_ = this.getBrowserEventType_(); |
| |
| // Some browsers do not support visibilityChange and therefore we don't bother |
| // setting up events. |
| if (this.eventType_) { |
| /** |
| * @private {goog.events.Key} |
| */ |
| this.eventKey_ = goog.events.listen(this.domHelper_.getDocument(), |
| this.eventType_, goog.bind(this.handleChange_, this)); |
| } |
| }; |
| goog.inherits(dom.PageVisibilityMonitor, goog.events.EventTarget); |
| |
| |
| /** |
| * @return {?string} The visibility change event type, or null if not supported. |
| * Memoized for performance. |
| * @private |
| */ |
| dom.PageVisibilityMonitor.prototype.getBrowserEventType_ = |
| goog.memoize(function() { |
| var isSupported = this.isSupported(); |
| var isPrefixed = this.isPrefixed_(); |
| |
| if (isSupported) { |
| return isPrefixed ? goog.dom.vendor.getPrefixedEventType( |
| goog.events.EventType.VISIBILITYCHANGE) : |
| goog.events.EventType.VISIBILITYCHANGE; |
| } else { |
| return null; |
| } |
| }); |
| |
| |
| /** |
| * @return {?string} The browser-specific document.hidden property. Memoized |
| * for performance. |
| * @private |
| */ |
| dom.PageVisibilityMonitor.prototype.getHiddenPropertyName_ = goog.memoize( |
| function() { |
| return goog.dom.vendor.getPrefixedPropertyName( |
| 'hidden', this.domHelper_.getDocument()); |
| }); |
| |
| |
| /** |
| * @return {boolean} Whether the visibility API is prefixed. |
| * @private |
| */ |
| dom.PageVisibilityMonitor.prototype.isPrefixed_ = function() { |
| return this.getHiddenPropertyName_() != 'hidden'; |
| }; |
| |
| |
| /** |
| * @return {?string} The browser-specific document.visibilityState property. |
| * Memoized for performance. |
| * @private |
| */ |
| dom.PageVisibilityMonitor.prototype.getVisibilityStatePropertyName_ = |
| goog.memoize(function() { |
| return goog.dom.vendor.getPrefixedPropertyName( |
| 'visibilityState', this.domHelper_.getDocument()); |
| }); |
| |
| |
| /** |
| * @return {boolean} Whether the visibility API is supported. |
| */ |
| dom.PageVisibilityMonitor.prototype.isSupported = function() { |
| return !!this.getHiddenPropertyName_(); |
| }; |
| |
| |
| /** |
| * @return {boolean} Whether the page is visible. |
| */ |
| dom.PageVisibilityMonitor.prototype.isHidden = function() { |
| return !!this.domHelper_.getDocument()[this.getHiddenPropertyName_()]; |
| }; |
| |
| |
| /** |
| * @return {?dom.PageVisibilityState} The page visibility state, or null if |
| * not supported. |
| */ |
| dom.PageVisibilityMonitor.prototype.getVisibilityState = function() { |
| if (!this.isSupported()) { |
| return null; |
| } |
| return this.domHelper_.getDocument()[this.getVisibilityStatePropertyName_()]; |
| }; |
| |
| |
| /** |
| * Handles the events on the element. |
| * @param {goog.events.BrowserEvent} e The underlying browser event. |
| * @private |
| */ |
| dom.PageVisibilityMonitor.prototype.handleChange_ = function(e) { |
| var state = this.getVisibilityState(); |
| var visibilityEvent = new dom.PageVisibilityEvent( |
| this.isHidden(), /** @type {dom.PageVisibilityState} */ (state)); |
| this.dispatchEvent(visibilityEvent); |
| }; |
| |
| |
| /** @override */ |
| dom.PageVisibilityMonitor.prototype.disposeInternal = function() { |
| goog.events.unlistenByKey(this.eventKey_); |
| dom.PageVisibilityMonitor.base(this, 'disposeInternal'); |
| }; |
| |
| |
| |
| /** |
| * A page visibility change event. |
| * @param {boolean} hidden Whether the page is hidden. |
| * @param {goog.labs.dom.PageVisibilityState} visibilityState A more detailed |
| * visibility state. |
| * @constructor |
| * @extends {goog.events.Event} |
| * @final |
| */ |
| dom.PageVisibilityEvent = function(hidden, visibilityState) { |
| dom.PageVisibilityEvent.base( |
| this, 'constructor', goog.events.EventType.VISIBILITYCHANGE); |
| |
| /** |
| * Whether the page is hidden. |
| * @type {boolean} |
| */ |
| this.hidden = hidden; |
| |
| /** |
| * A more detailed visibility state. |
| * @type {dom.PageVisibilityState} |
| */ |
| this.visibilityState = visibilityState; |
| }; |
| goog.inherits(dom.PageVisibilityEvent, goog.events.Event); |
| |
| }); // goog.scope |