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// Copyright 2008 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 Class that can be used to determine when an iframe is loaded.
*/
goog.provide('goog.net.IframeLoadMonitor');
goog.require('goog.dom');
goog.require('goog.events');
goog.require('goog.events.EventTarget');
goog.require('goog.events.EventType');
goog.require('goog.userAgent');
/**
* The correct way to determine whether an iframe has completed loading
* is different in IE and Firefox. This class abstracts above these
* differences, providing a consistent interface for:
* <ol>
* <li> Determing if an iframe is currently loaded
* <li> Listening for an iframe that is not currently loaded, to finish loading
* </ol>
*
* @param {HTMLIFrameElement} iframe An iframe.
* @param {boolean=} opt_hasContent Does the loaded iframe have content.
* @extends {goog.events.EventTarget}
* @constructor
*/
goog.net.IframeLoadMonitor = function(iframe, opt_hasContent) {
goog.base(this);
/**
* Iframe whose load state is monitored by this IframeLoadMonitor
* @type {HTMLIFrameElement}
* @private
*/
this.iframe_ = iframe;
/**
* Whether or not the loaded iframe has any content.
* @type {boolean}
* @private
*/
this.hasContent_ = !!opt_hasContent;
/**
* Whether or not the iframe is loaded.
* @type {boolean}
* @private
*/
this.isLoaded_ = this.isLoadedHelper_();
if (!this.isLoaded_) {
// IE 6 (and lower?) does not reliably fire load events, so listen to
// readystatechange.
// IE 7 does not reliably fire readystatechange events but listening on load
// seems to work just fine.
var isIe6OrLess = goog.userAgent.IE && !goog.userAgent.isVersion('7');
var loadEvtType = isIe6OrLess ?
goog.events.EventType.READYSTATECHANGE : goog.events.EventType.LOAD;
this.onloadListenerKey_ = goog.events.listen(
this.iframe_, loadEvtType, this.handleLoad_, false, this);
// Sometimes we still don't get the event callback, so we'll poll just to
// be safe.
this.intervalId_ = window.setInterval(
goog.bind(this.handleLoad_, this),
goog.net.IframeLoadMonitor.POLL_INTERVAL_MS_);
}
};
goog.inherits(goog.net.IframeLoadMonitor, goog.events.EventTarget);
/**
* Event type dispatched by a goog.net.IframeLoadMonitor when it internal iframe
* finishes loading for the first time after construction of the
* goog.net.IframeLoadMonitor
* @type {string}
*/
goog.net.IframeLoadMonitor.LOAD_EVENT = 'ifload';
/**
* Poll interval for polling iframe load states in milliseconds.
* @type {number}
* @private
*/
goog.net.IframeLoadMonitor.POLL_INTERVAL_MS_ = 100;
/**
* Key for iframe load listener, or null if not currently listening on the
* iframe for a load event.
* @type {?number}
* @private
*/
goog.net.IframeLoadMonitor.prototype.onloadListenerKey_ = null;
/**
* Returns whether or not the iframe is loaded.
* @return {boolean} whether or not the iframe is loaded.
*/
goog.net.IframeLoadMonitor.prototype.isLoaded = function() {
return this.isLoaded_;
};
/**
* Stops the poll timer if this IframeLoadMonitor is currently polling.
* @private
*/
goog.net.IframeLoadMonitor.prototype.maybeStopTimer_ = function() {
if (this.intervalId_) {
window.clearInterval(this.intervalId_);
this.intervalId_ = null;
}
};
/**
* Returns the iframe whose load state this IframeLoader monitors.
* @return {HTMLIFrameElement} the iframe whose load state this IframeLoader
* monitors.
*/
goog.net.IframeLoadMonitor.prototype.getIframe = function() {
return this.iframe_;
};
/** @override */
goog.net.IframeLoadMonitor.prototype.disposeInternal = function() {
delete this.iframe_;
this.maybeStopTimer_();
goog.events.unlistenByKey(this.onloadListenerKey_);
goog.net.IframeLoadMonitor.superClass_.disposeInternal.call(this);
};
/**
* Returns whether or not the iframe is loaded. Determines this by inspecting
* browser dependent properties of the iframe.
* @return {boolean} whether or not the iframe is loaded.
* @private
*/
goog.net.IframeLoadMonitor.prototype.isLoadedHelper_ = function() {
var isLoaded = false;
/** @preserveTry */
try {
// IE will reliably have readyState set to complete if the iframe is loaded
// For everything else, the iframe is loaded if there is a body and if the
// body should have content the firstChild exists. Firefox can fire
// the LOAD event and then a few hundred ms later replace the
// contentDocument once the content is loaded.
isLoaded = goog.userAgent.IE ? this.iframe_.readyState == 'complete' :
!!goog.dom.getFrameContentDocument(this.iframe_).body &&
(!this.hasContent_ ||
!!goog.dom.getFrameContentDocument(this.iframe_).body.firstChild);
} catch (e) {
// Ignore these errors. This just means that the iframe is not loaded
// IE will throw error reading readyState if the iframe is not appended
// to the dom yet.
// Firefox will throw error getting the iframe body if the iframe is not
// fully loaded.
}
return isLoaded;
};
/**
* Handles an event indicating that the loading status of the iframe has
* changed. In Firefox this is a goog.events.EventType.LOAD event, in IE
* this is a goog.events.EventType.READYSTATECHANGED
* @private
*/
goog.net.IframeLoadMonitor.prototype.handleLoad_ = function() {
// Only do the handler if the iframe is loaded.
if (this.isLoadedHelper_()) {
this.maybeStopTimer_();
goog.events.unlistenByKey(this.onloadListenerKey_);
this.onloadListenerKey_ = null;
this.isLoaded_ = true;
this.dispatchEvent(goog.net.IframeLoadMonitor.LOAD_EVENT);
}
};
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