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 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

 /* vim: set ts=2 et sw=2 tw=80 filetype=javascript: */

 /* 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/. */

 /**

  * Handles the download progress indicator in the taskbar.

  */

 "use strict";

 this.EXPORTED_SYMBOLS = [

   "DownloadsTaskbar",

 ];

 ////////////////////////////////////////////////////////////////////////////////

 //// Globals

 const Cc = Components.classes;

 const Ci = Components.interfaces;

 const Cu = Components.utils;

 const Cr = Components.results;

 Cu.import("resource://gre/modules/XPCOMUtils.jsm");

 XPCOMUtils.defineLazyModuleGetter(this, "Downloads",

                                   "resource://gre/modules/Downloads.jsm");

 XPCOMUtils.defineLazyModuleGetter(this, "RecentWindow",

                                   "resource:///modules/RecentWindow.jsm");

 XPCOMUtils.defineLazyModuleGetter(this, "Services",

                                   "resource://gre/modules/Services.jsm");

 XPCOMUtils.defineLazyGetter(this, "gWinTaskbar", function () {

   if (!("@mozilla.org/windows-taskbar;1" in Cc)) {

     return null;

   }

   let winTaskbar = Cc["@mozilla.org/windows-taskbar;1"]

                      .getService(Ci.nsIWinTaskbar);

   return winTaskbar.available && winTaskbar;

 });

 XPCOMUtils.defineLazyGetter(this, "gMacTaskbarProgress", function () {

   return ("@mozilla.org/widget/macdocksupport;1" in Cc) &&

          Cc["@mozilla.org/widget/macdocksupport;1"]

            .getService(Ci.nsITaskbarProgress);

 });

 ////////////////////////////////////////////////////////////////////////////////

 //// DownloadsTaskbar

 /**

  * Handles the download progress indicator in the taskbar.

  */

 this.DownloadsTaskbar = {

   /**

    * Underlying DownloadSummary providing the aggregate download information, or

    * null if the indicator has never been initialized.

    */

   _summary: null,

   /**

    * nsITaskbarProgress object to which download information is dispatched.

    * This can be null if the indicator has never been initialized or if the

    * indicator is currently hidden on Windows.

    */

   _taskbarProgress: null,

   /**

    * This method is called after a new browser window is opened, and ensures

    * that the download progress indicator is displayed in the taskbar.

    *

    * On Windows, the indicator is attached to the first browser window that

    * calls this method.  When the window is closed, the indicator is moved to

    * another browser window, if available, in no particular order.  When there

    * are no browser windows visible, the indicator is hidden.

    *

    * On Mac OS X, the indicator is initialized globally when this method is

    * called for the first time.  Subsequent calls have no effect.

    *

    * @param aBrowserWindow

    *        nsIDOMWindow object of the newly opened browser window to which the

    *        indicator may be attached.

    */

   registerIndicator: function (aBrowserWindow)

   {

     if (!this._taskbarProgress) {

       if (gMacTaskbarProgress) {

         // On Mac OS X, we have to register the global indicator only once.

         this._taskbarProgress = gMacTaskbarProgress;

         // Free the XPCOM reference on shutdown, to prevent detecting a leak.

         Services.obs.addObserver(() => {

           this._taskbarProgress = null;

           gMacTaskbarProgress = null;

         }, "quit-application-granted", false);

       } else if (gWinTaskbar) {

         // On Windows, the indicator is currently hidden because we have no

         // previous browser window, thus we should attach the indicator now.

         this._attachIndicator(aBrowserWindow);

       } else {

         // The taskbar indicator is not available on this platform.

         return;

       }

     }

     // Ensure that the DownloadSummary object will be created asynchronously.

     if (!this._summary) {

       Downloads.getSummary(Downloads.ALL).then(summary => {

         // In case the method is re-entered, we simply ignore redundant

         // invocations of the callback, instead of keeping separate state.

         if (this._summary) {

           return;

         }

         this._summary = summary;

         return this._summary.addView(this);

       }).then(null, Cu.reportError);

     }

   },

   /**

    * On Windows, attaches the taskbar indicator to the specified browser window.

    */

   _attachIndicator: function (aWindow)

   {

     // Activate the indicator on the specified window.

     let docShell = aWindow.QueryInterface(Ci.nsIInterfaceRequestor)

                           .getInterface(Ci.nsIWebNavigation)

                           .QueryInterface(Ci.nsIDocShellTreeItem).treeOwner

                           .QueryInterface(Ci.nsIInterfaceRequestor)

                           .getInterface(Ci.nsIXULWindow).docShell;

     this._taskbarProgress = gWinTaskbar.getTaskbarProgress(docShell);

     // If the DownloadSummary object has already been created, we should update

     // the state of the new indicator, otherwise it will be updated as soon as

     // the DownloadSummary view is registered.

     if (this._summary) {

       this.onSummaryChanged();

     }

     aWindow.addEventListener("unload", () => {

       // Locate another browser window, excluding the one being closed.

       let browserWindow = RecentWindow.getMostRecentBrowserWindow();

       if (browserWindow) {

         // Move the progress indicator to the other browser window.

         this._attachIndicator(browserWindow);

       } else {

         // The last browser window has been closed.  We remove the reference to

         // the taskbar progress object so that the indicator will be registered

         // again on the next browser window that is opened.

         this._taskbarProgress = null;

       }

     }, false);

   },

   //////////////////////////////////////////////////////////////////////////////

   //// DownloadSummary view

   onSummaryChanged: function ()

   {

     // If the last browser window has been closed, we have no indicator anymore.

     if (!this._taskbarProgress) {

       return;

     }

     if (this._summary.allHaveStopped || this._summary.progressTotalBytes == 0) {

       this._taskbarProgress.setProgressState(

                                Ci.nsITaskbarProgress.STATE_NO_PROGRESS, 0, 0);

     } else {

       // For a brief moment before completion, some download components may

       // report more transferred bytes than the total number of bytes.  Thus,

       // ensure that we never break the expectations of the progress indicator.

       let progressCurrentBytes = Math.min(this._summary.progressTotalBytes,

                                           this._summary.progressCurrentBytes);

       this._taskbarProgress.setProgressState(

                                Ci.nsITaskbarProgress.STATE_NORMAL,

                                progressCurrentBytes,

                                this._summary.progressTotalBytes);

     }

   },

 };