The Tor Browser: browser/modules/SharedFrame.jsm@b8a032363ba2 (annotated)

browser/modules/SharedFrame.jsm@b8a032363ba2 (annotated)

browser/modules/SharedFrame.jsm

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 "use strict";
 this.EXPORTED_SYMBOLS = [ "SharedFrame" ];
 const Ci = Components.interfaces;
 const Cu = Components.utils;
 /**
  * The purpose of this module is to create and group various iframe
  * elements that are meant to all display the same content and only
  * one at a time. This makes it possible to have the content loaded
  * only once, while the other iframes can be kept as placeholders to
  * quickly move the content to them through the swapFrameLoaders function
  * when another one of the placeholder is meant to be displayed.
  * */
 let Frames = new Map();
 /**
  * The Frames map is the main data structure that holds information
  * about the groups being tracked. Each entry's key is the group name,
  * and the object holds information about what is the URL being displayed
  * on that group, and what is the active element on the group (the frame that
  * holds the loaded content).
  * The reference to the activeFrame is a weak reference, which allows the
  * frame to go away at any time, and when that happens the module considers that
  * there are no active elements in that group. The group can be reactivated
  * by changing the URL, calling preload again or adding a new element.
  *
  *
  *  Frames = {
  *    "messages-panel": {
  *      url: string,
  *      activeFrame: weakref
  *    }
  *  }
  *
  * Each object on the map is called a _SharedFrameGroup, which is an internal
  * class of this module which does not automatically keep track of its state. This
  * object should not be used externally, and all control should be handled by the
  * module's functions.
  */
 function UNLOADED_URL(aStr) "data:text/html;charset=utf-8,<!-- Unloaded frame " + aStr + " -->";
 this.SharedFrame = {
   /**
    * Creates an iframe element and track it as part of the specified group
    * The module must create the iframe itself because it needs to do some special
    * handling for the element's src attribute.
    *
    * @param aGroupName        the name of the group to which this frame belongs
    * @param aParent           the parent element to which the frame will be appended to
    * @param aFrameAttributes  an object with a list of attributes to set in the iframe
    *                          before appending it to the DOM. The "src" attribute has
    *                          special meaning here and if it's not blank it specifies
    *                          the URL that will be initially assigned to this group
    * @param aPreload          optional, tells if the URL specified in the src attribute
    *                          should be preloaded in the frame being created, in case
    *                          it's not yet preloaded in any other frame of the group.
    *                          This parameter has no meaning if src is blank.
    */
   createFrame: function (aGroupName, aParent, aFrameAttributes, aPreload = true) {
     let frame = aParent.ownerDocument.createElement("iframe");
     for (let [key, val] of Iterator(aFrameAttributes)) {
       frame.setAttribute(key, val);
     }
     let src = aFrameAttributes.src;
     if (!src) {
       aPreload = false;
     }
     let group = Frames.get(aGroupName);
     if (group) {
       // If this group has already been created
       if (aPreload && !group.isAlive) {
         // If aPreload is set and the group is not already loaded, load it.
         // This can happen if:
         // - aPreload was not used while creating the previous frames of this group, or
         // - the previously active frame went dead in the meantime
         group.url = src;
         this.preload(aGroupName, frame);
       } else {
         // If aPreload is not set, or the group is already loaded in a different frame,
         // there's not much that we need to do here: just create this frame as an
         // inactivate placeholder
         frame.setAttribute("src", UNLOADED_URL(aGroupName));
       }
     } else {
       // This is the first time we hear about this group, so let's start tracking it,
       // and also preload it if the src attribute was set and aPreload = true
       group = new _SharedFrameGroup(src);
       Frames.set(aGroupName, group);
       if (aPreload) {
         this.preload(aGroupName, frame);
       } else {
         frame.setAttribute("src", UNLOADED_URL(aGroupName));
       }
     }
     aParent.appendChild(frame);
     return frame;
   },
   /**
    * Function that moves the loaded content from one active frame to
    * another one that is currently a placeholder. If there's no active
    * frame in the group, the content is loaded/reloaded.
    *
    * @param aGroupName   the name of the group
    * @param aTargetFrame the frame element to which the content should
    *                     be moved to.
    */
   setOwner: function (aGroupName, aTargetFrame) {
     let group = Frames.get(aGroupName);
     let frame = group.activeFrame;
     if (frame == aTargetFrame) {
       // nothing to do here
       return;
     }
     if (group.isAlive) {
       // Move document ownership to the desired frame, and make it the active one
       frame.QueryInterface(Ci.nsIFrameLoaderOwner).swapFrameLoaders(aTargetFrame);
       group.activeFrame = aTargetFrame;
     } else {
       // Previous owner was dead, reload the document at the new owner and make it the active one
       aTargetFrame.setAttribute("src", group.url);
       group.activeFrame = aTargetFrame;
     }
   },
   /**
    * Updates the current URL in use by this group, and loads it into the active frame.
    *
    * @param aGroupName  the name of the group
    * @param aURL        the new url
    */
   updateURL: function (aGroupName, aURL) {
     let group = Frames.get(aGroupName);
     group.url = aURL;
     if (group.isAlive) {
       group.activeFrame.setAttribute("src", aURL);
     }
   },
   /**
    * Loads the group's url into a target frame, if the group doesn't have a currently
    * active frame.
    *
    * @param aGroupName    the name of the group
    * @param aTargetFrame  the frame element which should be made active and
    *                      have the group's content loaded to
    */
   preload: function (aGroupName, aTargetFrame) {
     let group = Frames.get(aGroupName);
     if (!group.isAlive) {
       aTargetFrame.setAttribute("src", group.url);
       group.activeFrame = aTargetFrame;
     }
   },
   /**
    * Tells if a group currently have an active element.
    *
    * @param aGroupName  the name of the group
    */
   isGroupAlive: function (aGroupName) {
     return Frames.get(aGroupName).isAlive;
   },
   /**
    * Forgets about this group. This function doesn't need to be used
    * unless the group's name needs to be reused.
    *
    * @param aGroupName  the name of the group
    */
   forgetGroup: function (aGroupName) {
     Frames.delete(aGroupName);
   }
 }
 function _SharedFrameGroup(aURL) {
   this.url = aURL;
   this._activeFrame = null;
 }
 _SharedFrameGroup.prototype = {
   get isAlive() {
     let frame = this.activeFrame;
     return !!(frame &&
               frame.contentDocument &&
               frame.contentDocument.location);
   },
   get activeFrame() {
     return this._activeFrame &&
            this._activeFrame.get();
   },
   set activeFrame(aActiveFrame) {
     this._activeFrame = aActiveFrame
                         ? Cu.getWeakReference(aActiveFrame)
                         : null;
   }
 }

The Tor Browser / annotate

browser/modules/SharedFrame.jsm@b8a032363ba2 (annotated)

browser/modules/SharedFrame.jsm