remoting/webapp/cast_extension_handler.js

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 /**
   6  * @fileoverview Description of this file.
   7  * Class handling interaction with the cast extension session of the Chromoting
   8  * host. It receives and sends extension messages from/to the host through
   9  * the client session. It uses the Google Cast Chrome Sender API library to
  10  * interact with nearby Cast receivers.
  11  *
  12  * Once it establishes connection with a Cast device (upon user choice), it
  13  * creates a session, loads our registered receiver application and then becomes
  14  * a message proxy between the host and cast device, helping negotiate
  15  * their peer connection.
  16  */
  17
  18 'use strict';
  19
  20 /** @suppress {duplicate} */
  21 var remoting = remoting || {};
  22
  23 /**
  24  * @constructor
  25  * @param {!remoting.ClientSession} clientSession The client session to send
  26  * cast extension messages to.
  27  */
  28 remoting.CastExtensionHandler = function(clientSession) {
  29   /** @private */
  30   this.clientSession_ = clientSession;
  31
  32   /** @type {chrome.cast.Session} @private */
  33   this.session_ = null;
  34
  35   /** @type {string} @private */
  36   this.kCastNamespace_ = 'urn:x-cast:com.chromoting.cast.all';
  37
  38   /** @type {string} @private */
  39   this.kApplicationId_ = "8A1211E3";
  40
  41   /** @type {Array.<Object>} @private */
  42   this.messageQueue_ = [];
  43
  44   this.start_();
  45 };
  46
  47 /**
  48  * The id of the script node.
  49  * @type {string}
  50  * @private
  51  */
  52 remoting.CastExtensionHandler.prototype.SCRIPT_NODE_ID_ = 'cast-script-node';
  53
  54 /**
  55  * Attempts to load the Google Cast Chrome Sender API libary.
  56  * @private
  57  */
  58 remoting.CastExtensionHandler.prototype.start_ = function() {
  59   var node = document.getElementById(this.SCRIPT_NODE_ID_);
  60   if (node) {
  61     console.error(
  62         'Multiple calls to CastExtensionHandler.start_ not expected.');
  63     return;
  64   }
  65
  66   // Create a script node to load the Cast Sender API.
  67   node = document.createElement('script');
  68   node.id = this.SCRIPT_NODE_ID_;
  69   node.src = "https://www.gstatic.com/cv/js/sender/v1/cast_sender.js";
  70   node.type = 'text/javascript';
  71   document.body.insertBefore(node, document.body.firstChild);
  72
  73   /** @type {remoting.CastExtensionHandler} */
  74   var that = this;
  75   var onLoad = function() {
  76     window['__onGCastApiAvailable'] = that.onGCastApiAvailable.bind(that);
  77
  78   };
  79   var onLoadError = function(event) {
  80     console.error("Failed to load Chrome Cast Sender API.");
  81   }
  82   node.addEventListener('load', onLoad, false);
  83   node.addEventListener('error', onLoadError, false);
  84
  85 };
  86
  87 /**
  88  * Process Cast Extension Messages from the Chromoting host.
  89  * @param {string} msgString The extension message's data.
  90  */
  91 remoting.CastExtensionHandler.prototype.onMessage = function(msgString) {
  92   var message = getJsonObjectFromString(msgString);
  93
  94   // Save messages to send after a session is established.
  95   this.messageQueue_.push(message);
  96   // Trigger the sending of pending messages, followed by the one just
  97   // received.
  98   if (this.session_) {
  99     this.sendPendingMessages_();
 100   }
 101 };
 102
 103 /**
 104  * Send cast-extension messages through the client session.
 105  * @param {Object} response The JSON response to be sent to the host. The
 106  * response object must contain the appropriate keys.
 107  * @private
 108  */
 109 remoting.CastExtensionHandler.prototype.sendMessageToHost_ =
 110     function(response) {
 111   this.clientSession_.sendCastExtensionMessage(response);
 112 };
 113
 114 /**
 115  * Send pending messages from the host to the receiver app.
 116  * @private
 117  */
 118 remoting.CastExtensionHandler.prototype.sendPendingMessages_ = function() {
 119   var len = this.messageQueue_.length;
 120   for(var i = 0; i<len; i++) {
 121     this.session_.sendMessage(this.kCastNamespace_,
 122                               this.messageQueue_[i],
 123                               this.sendMessageSuccess.bind(this),
 124                               this.sendMessageFailure.bind(this));
 125   }
 126   this.messageQueue_ = [];
 127 };
 128
 129 /**
 130  * Event handler for '__onGCastApiAvailable' window event. This event is
 131  * triggered if the Google Cast Chrome Sender API is available. We attempt to
 132  * load this API in this.start(). If the API loaded successfully, we can proceed
 133  * to initialize it and configure it to launch our Cast Receiver Application.
 134  *
 135  * @param {boolean} loaded True if the API loaded succesfully.
 136  * @param {Object} errorInfo Info if the API load failed.
 137  */
 138 remoting.CastExtensionHandler.prototype.onGCastApiAvailable =
 139     function(loaded, errorInfo) {
 140   if (loaded) {
 141     this.initializeCastApi();
 142   } else {
 143     console.log(errorInfo);
 144   }
 145 };
 146
 147 /**
 148  * Initialize the Cast API.
 149  * @private
 150  */
 151 remoting.CastExtensionHandler.prototype.initializeCastApi = function() {
 152   var sessionRequest = new chrome.cast.SessionRequest(this.kApplicationId_);
 153   var apiConfig =
 154       new chrome.cast.ApiConfig(sessionRequest,
 155                                 this.sessionListener.bind(this),
 156                                 this.receiverListener.bind(this),
 157                                 chrome.cast.AutoJoinPolicy.PAGE_SCOPED,
 158                                 chrome.cast.DefaultActionPolicy.CREATE_SESSION);
 159   chrome.cast.initialize(
 160       apiConfig, this.onInitSuccess.bind(this), this.onInitError.bind(this));
 161 };
 162
 163 /**
 164  * Callback for successful initialization of the Cast API.
 165  */
 166 remoting.CastExtensionHandler.prototype.onInitSuccess = function() {
 167   console.log("Initialization Successful.");
 168 };
 169
 170 /**
 171  * Callback for failed initialization of the Cast API.
 172  */
 173 remoting.CastExtensionHandler.prototype.onInitError = function() {
 174   console.error("Initialization Failed.");
 175 };
 176
 177 /**
 178  * Listener invoked when a session is created or connected by the SDK.
 179  * Note: The requestSession method would not cause this callback to be invoked
 180  * since it is passed its own listener.
 181  * @param {chrome.cast.Session} session The resulting session.
 182  */
 183 remoting.CastExtensionHandler.prototype.sessionListener = function(session) {
 184   console.log('New Session:' + /** @type {string} */ (session.sessionId));
 185   this.session_ = session;
 186   if (this.session_.media.length != 0) {
 187
 188     // There should be no media associated with the session, since we never
 189     // directly load media from the Sender application.
 190     this.onMediaDiscovered('sessionListener', this.session_.media[0]);
 191   }
 192   this.session_.addMediaListener(
 193       this.onMediaDiscovered.bind(this, 'addMediaListener'));
 194   this.session_.addUpdateListener(this.sessionUpdateListener.bind(this));
 195   this.session_.addMessageListener(this.kCastNamespace_,
 196                                    this.chromotingMessageListener.bind(this));
 197   this.session_.sendMessage(this.kCastNamespace_,
 198       {subject : 'test', chromoting_data : 'Hello, Cast.'},
 199       this.sendMessageSuccess.bind(this),
 200       this.sendMessageFailure.bind(this));
 201   this.sendPendingMessages_();
 202 };
 203
 204 /**
 205  * Listener invoked when a media session is created by another sender.
 206  * @param {string} how How this callback was triggered.
 207  * @param {chrome.cast.media.Media} media The media item discovered.
 208  * @private
 209  */
 210 remoting.CastExtensionHandler.prototype.onMediaDiscovered =
 211     function(how, media) {
 212       console.error("Unexpected media session discovered.");
 213 };
 214
 215 /**
 216  * Listener invoked when a cast extension message was sent to the cast device
 217  * successfully.
 218  * @private
 219  */
 220 remoting.CastExtensionHandler.prototype.sendMessageSuccess = function() {
 221 };
 222
 223 /**
 224  * Listener invoked when a cast extension message failed to be sent to the cast
 225  * device.
 226  * @param {Object} error The error.
 227  * @private
 228  */
 229 remoting.CastExtensionHandler.prototype.sendMessageFailure = function(error) {
 230   console.error('Failed to Send Message.', error);
 231 };
 232
 233 /**
 234  * Listener invoked when a cast extension message is received from the Cast
 235  * device.
 236  * @param {string} ns The namespace of the message received.
 237  * @param {string} message The stringified JSON message received.
 238  */
 239 remoting.CastExtensionHandler.prototype.chromotingMessageListener =
 240     function(ns, message) {
 241   if (ns === this.kCastNamespace_) {
 242     try {
 243         var messageObj = getJsonObjectFromString(message);
 244         this.sendMessageToHost_(messageObj);
 245     } catch (err) {
 246       console.error('Failed to process message from Cast device.');
 247     }
 248   } else {
 249     console.error("Unexpected message from Cast device.");
 250   }
 251 };
 252
 253 /**
 254  * Listener invoked when there updates to the current session.
 255  *
 256  * @param {boolean} isAlive True if the session is still alive.
 257  */
 258 remoting.CastExtensionHandler.prototype.sessionUpdateListener =
 259     function(isAlive) {
 260   var message = isAlive ? 'Session Updated' : 'Session Removed';
 261   message += ': ' + this.session_.sessionId +'.';
 262   console.log(message);
 263 };
 264
 265 /**
 266  * Listener invoked when the availability of a Cast receiver that supports
 267  * the application in sessionRequest is known or changes.
 268  *
 269  * @param {chrome.cast.ReceiverAvailability} availability Receiver availability.
 270  */
 271 remoting.CastExtensionHandler.prototype.receiverListener =
 272     function(availability) {
 273   if (availability === chrome.cast.ReceiverAvailability.AVAILABLE) {
 274     console.log("Receiver(s) Found.");
 275   } else {
 276     console.error("No Receivers Available.");
 277   }
 278 };
 279
 280 /**
 281  * Launches the associated receiver application by requesting that it be created
 282  * on the Cast device. It uses the SessionRequest passed during initialization
 283  * to determine what application to launch on the Cast device.
 284  *
 285  * Note: This method is intended to be used as a click listener for a custom
 286  * cast button on the webpage. We currently use the default cast button in
 287  * Chrome, so this method is unused.
 288  */
 289 remoting.CastExtensionHandler.prototype.launchApp = function() {
 290   chrome.cast.requestSession(this.onRequestSessionSuccess.bind(this),
 291                              this.onLaunchError.bind(this));
 292 };
 293
 294 /**
 295  * Listener invoked when chrome.cast.requestSession completes successfully.
 296  *
 297  * @param {chrome.cast.Session} session The requested session.
 298  */
 299 remoting.CastExtensionHandler.prototype.onRequestSessionSuccess =
 300     function (session) {
 301   this.session_ = session;
 302   this.session_.addUpdateListener(this.sessionUpdateListener.bind(this));
 303   if (this.session_.media.length != 0) {
 304     this.onMediaDiscovered('onRequestSession', this.session_.media[0]);
 305   }
 306   this.session_.addMediaListener(
 307       this.onMediaDiscovered.bind(this, 'addMediaListener'));
 308   this.session_.addMessageListener(this.kCastNamespace_,
 309                                    this.chromotingMessageListener.bind(this));
 310 };
 311
 312 /**
 313  * Listener invoked when chrome.cast.requestSession fails.
 314  * @param {chrome.cast.Error} error The error code.
 315  */
 316 remoting.CastExtensionHandler.prototype.onLaunchError = function(error) {
 317   console.error("Error Casting to Receiver.", error);
 318 };
 319
 320 /**
 321  * Stops the running receiver application associated with the session.
 322  * TODO(aiguha): When the user disconnects using the blue drop down bar,
 323  * the client session should notify the CastExtensionHandler, which should
 324  * call this method to close the session with the Cast device.
 325  */
 326 remoting.CastExtensionHandler.prototype.stopApp = function() {
 327   this.session_.stop(this.onStopAppSuccess.bind(this),
 328                      this.onStopAppError.bind(this));
 329 };
 330
 331 /**
 332  * Listener invoked when the receiver application is stopped successfully.
 333  */
 334 remoting.CastExtensionHandler.prototype.onStopAppSuccess = function() {
 335 };
 336
 337 /**
 338  * Listener invoked when we fail to stop the receiver application.
 339  *
 340  * @param {chrome.cast.Error} error The error code.
 341  */
 342 remoting.CastExtensionHandler.prototype.onStopAppError = function(error) {
 343   console.error('Error Stopping App: ', error);
 344 };