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 /**
  15  * Interface for the native event system layer.  This interface is designed
  16  * to be used on the main application thread only.
  17  */
  18 [uuid(7cd5c71d-223b-4afe-931d-5eedb1f2b01f)]
  19 interface nsIAppShell : nsISupports
  20 {
  21   /**
  22    * Enter an event loop.  Don't leave until exit() is called.
  23    */
  24   void run();
  25
  26   /**
  27    * Exit the handle event loop
  28    */
  29   void exit();
  30
  31   /**
  32    * Give hint to native event queue notification mechanism. If the native
  33    * platform needs to tradeoff performance vs. native event starvation this
  34    * hint tells the native dispatch code which to favor.  The default is to
  35    * prevent native event starvation.
  36    *
  37    * Calls to this function may be nested. When the number of calls that pass
  38    * PR_TRUE is subtracted from the number of calls that pass PR_FALSE is
  39    * greater than 0, performance is given precedence over preventing event
  40    * starvation.
  41    *
  42    * The starvationDelay arg is only used when favorPerfOverStarvation is
  43    * PR_FALSE. It is the amount of time in milliseconds to wait before the
  44    * PR_FALSE actually takes effect.
  45    */
  46   void favorPerformanceHint(in boolean favorPerfOverStarvation,
  47                             in unsigned long starvationDelay);
  48
  49   /**
  50    * Suspends the use of additional platform-specific methods (besides the
  51    * nsIAppShell->run() event loop) to run Gecko events on the main
  52    * application thread.  Under some circumstances these "additional methods"
  53    * can cause Gecko event handlers to be re-entered, sometimes leading to
  54    * hangs and crashes.  Calls to suspendNative() and resumeNative() may be
  55    * nested.  On some platforms (those that don't use any "additional
  56    * methods") this will be a no-op.  Does not (in itself) stop Gecko events
  57    * from being processed on the main application thread.  But if the
  58    * nsIAppShell->run() event loop is blocked when this call is made, Gecko
  59    * events will stop being processed until resumeNative() is called (even
  60    * if a plugin or library is temporarily processing events on a nested
  61    * event loop).
  62    */
  63   void suspendNative();
  64
  65   /**
  66    * Resumes the use of additional platform-specific methods to run Gecko
  67    * events on the main application thread.  Calls to suspendNative() and
  68    * resumeNative() may be nested.  On some platforms this will be a no-op.
  69    */
  70   void resumeNative();
  71
  72   /**
  73    * The current event loop nesting level.
  74    */
  75   readonly attribute unsigned long eventloopNestingLevel;
  76 };