chrome/browser/resources/chromeos/chromevox/common/interframe.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 Tools for interframe communication. To use this class, every
   7  * window that wants to communicate with its child iframes should enumerate
   8  * them using document.getElementsByTagName('iframe'), create an ID to
   9  * associate with that iframe, then call cvox.Interframe.sendIdToIFrame
  10  * on each of them. Then use cvox.Interframe.sendMessageToIFrame to send
  11  * messages to that iframe and cvox.Interframe.addListener to receive
  12  * replies. When a reply is received, it will automatically contain the ID of
  13  * that iframe as a parameter.
  14  *
  15  */
  16
  17 goog.provide('cvox.Interframe');
  18
  19 goog.require('cvox.ChromeVoxJSON');
  20 goog.require('cvox.DomUtil');
  21
  22 /**
  23  * @constructor
  24  */
  25 cvox.Interframe = function() {
  26 };
  27
  28 /**
  29  * The prefix of all interframe messages.
  30  * @type {string}
  31  * @const
  32  */
  33 cvox.Interframe.IF_MSG_PREFIX = 'cvox.INTERFRAME:';
  34
  35 /**
  36  * The message used to set the ID of a child frame so that it can send replies
  37  * to its parent frame.
  38  * @type {string}
  39  * @const
  40  */
  41 cvox.Interframe.SET_ID = 'cvox.INTERFRAME_SET_ID';
  42
  43 /**
  44  * The message used by a child frame to acknowledge an id was set (sent to its
  45  * parent frame.
  46  * @type {string}
  47  * @const
  48  */
  49 cvox.Interframe.ACK_SET_ID = 'cvox.INTERFRAME_ACK_SET_ID';
  50
  51 /**
  52  * The ID of this window (relative to its parent farme).
  53  * @type {number|string|undefined}
  54  */
  55 cvox.Interframe.id;
  56
  57 /**
  58  * Array of functions that have been registered as listeners to interframe
  59  * messages send to this window.
  60  * @type {Array<function(Object)>}
  61  */
  62 cvox.Interframe.listeners = [];
  63
  64 /**
  65  * Maps an id to a function which gets called when a frame first sends an ack
  66  * for a set id msg.
  67  @dict {!Object<number|string, function()>}
  68  * @private
  69  */
  70 cvox.Interframe.idToCallback_ = {};
  71
  72 /**
  73  * Flag for unit testing. When false, skips over iframe.contentWindow check
  74  * in sendMessageToIframe. This is needed because in the wild, ChromeVox may
  75  * not have access to iframe.contentWindow due to the same-origin security
  76  * policy. There is no reason to set this outside of a test.
  77  * @type {boolean}
  78  */
  79 cvox.Interframe.allowAccessToIframeContentWindow = true;
  80
  81 /**
  82  * Initializes the cvox.Interframe module. (This is called automatically.)
  83  */
  84 cvox.Interframe.init = function() {
  85   cvox.Interframe.messageListener = function(event) {
  86     if (typeof event.data === 'string' &&
  87         event.data.indexOf(cvox.Interframe.IF_MSG_PREFIX) == 0) {
  88       var suffix = event.data.substr(cvox.Interframe.IF_MSG_PREFIX.length);
  89       var message = /** @type {Object} */ (
  90           cvox.ChromeVoxJSON.parse(suffix));
  91       if (message['command'] == cvox.Interframe.SET_ID) {
  92         cvox.Interframe.id = message['id'];
  93         message['command'] = cvox.Interframe.ACK_SET_ID;
  94         cvox.Interframe.sendMessageToParentWindow(message);
  95       } else if (message['command'] == cvox.Interframe.ACK_SET_ID) {
  96         cvox.Interframe.id = message['id'];
  97         var callback = cvox.Interframe.idToCallback_[cvox.Interframe.id];
  98         callback();
  99       }
 100       for (var i = 0, listener; listener = cvox.Interframe.listeners[i]; i++) {
 101         listener(message);
 102       }
 103     }
 104     return false;
 105   };
 106   window.addEventListener('message', cvox.Interframe.messageListener, true);
 107 };
 108
 109 /**
 110  * Unregister the main window event listener. Intended for clean unit testing;
 111  * normally there's no reason to call this outside of a test.
 112  */
 113 cvox.Interframe.shutdown = function() {
 114   window.removeEventListener('message', cvox.Interframe.messageListener, true);
 115 };
 116
 117 /**
 118  * Register a function to listen to all interframe communication messages.
 119  * Messages from a child frame will have a parameter 'id' that you assigned
 120  * when you called cvox.Interframe.sendIdToIFrame.
 121  * @param {function(Object)} listener The listener function.
 122  */
 123 cvox.Interframe.addListener = function(listener) {
 124   cvox.Interframe.listeners.push(listener);
 125 };
 126
 127 /**
 128  * Send a message to another window.
 129  * @param {Object} message The message to send.
 130  * @param {Window} window The window to receive the message.
 131  */
 132 cvox.Interframe.sendMessageToWindow = function(message, window) {
 133   var encodedMessage = cvox.Interframe.IF_MSG_PREFIX +
 134       cvox.ChromeVoxJSON.stringify(message, null, null);
 135   window.postMessage(encodedMessage, '*');
 136 };
 137
 138 /**
 139  * Send a message to another iframe.
 140  * @param {Object} message The message to send. The message must have an 'id'
 141  *     parameter in order to be sent.
 142  * @param {HTMLIFrameElement} iframe The iframe to send the message to.
 143  */
 144 cvox.Interframe.sendMessageToIFrame = function(message, iframe) {
 145   if (cvox.Interframe.allowAccessToIframeContentWindow &&
 146       iframe.contentWindow) {
 147     cvox.Interframe.sendMessageToWindow(message, iframe.contentWindow);
 148     return;
 149   }
 150
 151   // A content script can't access window.parent, but the page can, so
 152   // inject a tiny bit of javascript into the page.
 153   var encodedMessage = cvox.Interframe.IF_MSG_PREFIX +
 154       cvox.ChromeVoxJSON.stringify(message, null, null);
 155   var script = document.createElement('script');
 156   script.type = 'text/javascript';
 157
 158   // TODO: Make this logic more like makeNodeReference_ inside api.js
 159   // (line 126) so we can use an attribute instead of a classname
 160   if (iframe.hasAttribute('id') &&
 161       document.getElementById(iframe.id) == iframe) {
 162     // Ideally, try to send it based on the iframe's existing id.
 163     script.innerHTML =
 164         'document.getElementById(decodeURI(\'' +
 165         encodeURI(iframe.id) + '\')).contentWindow.postMessage(decodeURI(\'' +
 166         encodeURI(encodedMessage) + '\'), \'*\');';
 167   } else {
 168     // If not, add a style name and send it based on that.
 169     var styleName = 'cvox_iframe' + message['id'];
 170     if (iframe.className === '') {
 171       iframe.className = styleName;
 172     } else if (iframe.className.indexOf(styleName) == -1) {
 173       iframe.className += ' ' + styleName;
 174     }
 175
 176     script.innerHTML =
 177         'document.getElementsByClassName(decodeURI(\'' +
 178         encodeURI(styleName) +
 179         '\'))[0].contentWindow.postMessage(decodeURI(\'' +
 180         encodeURI(encodedMessage) + '\'), \'*\');';
 181   }
 182
 183   // Remove the script so we don't leave any clutter.
 184   document.head.appendChild(script);
 185   window.setTimeout(function() {
 186     document.head.removeChild(script);
 187   }, 1000);
 188 };
 189
 190 /**
 191  * Send a message to the parent window of this window, if any. If the parent
 192  * assigned this window an ID, sends back the ID in the reply automatically.
 193  * @param {Object} message The message to send.
 194  */
 195 cvox.Interframe.sendMessageToParentWindow = function(message) {
 196   if (!cvox.Interframe.isIframe()) {
 197     return;
 198   }
 199
 200   message['sourceId'] = cvox.Interframe.id;
 201   if (window.parent) {
 202     cvox.Interframe.sendMessageToWindow(message, window.parent);
 203     return;
 204   }
 205
 206   // A content script can't access window.parent, but the page can, so
 207   // use window.location.href to execute a simple line of javascript in
 208   // the page context.
 209   var encodedMessage = cvox.Interframe.IF_MSG_PREFIX +
 210       cvox.ChromeVoxJSON.stringify(message, null, null);
 211   window.location.href =
 212       'javascript:window.parent.postMessage(\'' +
 213       encodeURI(encodedMessage) + '\', \'*\');';
 214 };
 215
 216 /**
 217  * Send the given ID to a child iframe.
 218  * @param {number|string} id The ID you want to receive in replies from
 219  *     this iframe.
 220  * @param {HTMLIFrameElement} iframe The iframe to assign.
 221  * @param {function()=} opt_callback Called when a ack msg arrives from the
 222  *frame.
 223  */
 224 cvox.Interframe.sendIdToIFrame = function(id, iframe, opt_callback) {
 225   if (opt_callback) {
 226     cvox.Interframe.idToCallback_[id] = opt_callback;
 227   }
 228   var message = {'command': cvox.Interframe.SET_ID, 'id': id};
 229   cvox.Interframe.sendMessageToIFrame(message, iframe);
 230 };
 231
 232 /**
 233  * Returns true if inside iframe
 234  * @return {boolean} true if inside iframe.
 235  */
 236 cvox.Interframe.isIframe = function() {
 237   return (window != window.parent);
 238 };
 239
 240 cvox.Interframe.init();