widget/nsIAppShell.idl

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  *
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "nsISupports.idl"
   8
   9 interface nsIRunnable;
  10 %{ C++
  11 template <class T> struct already_AddRefed;
  12
  13 /**
  14  * After the default timezone changes, this topic is notified. Some systems may
  15  * not support monitoring timezone.
  16  */
  17 #define DEFAULT_TIMEZONE_CHANGED_OBSERVER_TOPIC "default-timezone-changed"
  18 %}
  19
  20 /**
  21  * Interface for the native event system layer.  This interface is designed
  22  * to be used on the main application thread only.
  23  */
  24 [uuid(7cd5c71d-223b-4afe-931d-5eedb1f2b01f)]
  25 interface nsIAppShell : nsISupports
  26 {
  27   /**
  28    * Enter an event loop.  Don't leave until exit() is called.
  29    */
  30   void run();
  31
  32   /**
  33    * Exit the handle event loop
  34    */
  35   void exit();
  36
  37   /**
  38    * Give hint to native event queue notification mechanism. If the native
  39    * platform needs to tradeoff performance vs. native event starvation this
  40    * hint tells the native dispatch code which to favor.  The default is to
  41    * prevent native event starvation.
  42    *
  43    * Calls to this function may be nested. When the number of calls that pass
  44    * PR_TRUE is subtracted from the number of calls that pass PR_FALSE is
  45    * greater than 0, performance is given precedence over preventing event
  46    * starvation.
  47    *
  48    * The starvationDelay arg is only used when favorPerfOverStarvation is
  49    * PR_FALSE. It is the amount of time in milliseconds to wait before the
  50    * PR_FALSE actually takes effect.
  51    */
  52   void favorPerformanceHint(in boolean favorPerfOverStarvation,
  53                             in unsigned long starvationDelay);
  54
  55   /**
  56    * Suspends the use of additional platform-specific methods (besides the
  57    * nsIAppShell->run() event loop) to run Gecko events on the main
  58    * application thread.  Under some circumstances these "additional methods"
  59    * can cause Gecko event handlers to be re-entered, sometimes leading to
  60    * hangs and crashes.  Calls to suspendNative() and resumeNative() may be
  61    * nested.  On some platforms (those that don't use any "additional
  62    * methods") this will be a no-op.  Does not (in itself) stop Gecko events
  63    * from being processed on the main application thread.  But if the
  64    * nsIAppShell->run() event loop is blocked when this call is made, Gecko
  65    * events will stop being processed until resumeNative() is called (even
  66    * if a plugin or library is temporarily processing events on a nested
  67    * event loop).
  68    */
  69   void suspendNative();
  70
  71   /**
  72    * Resumes the use of additional platform-specific methods to run Gecko
  73    * events on the main application thread.  Calls to suspendNative() and
  74    * resumeNative() may be nested.  On some platforms this will be a no-op.
  75    */
  76   void resumeNative();
  77
  78   /**
  79    * The current event loop nesting level.
  80    */
  81   readonly attribute unsigned long eventloopNestingLevel;
  82 };