widget/src/xpwidgets/nsBaseAppShell.h

   1 /* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
   2 /* ***** BEGIN LICENSE BLOCK *****
   3  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   4  *
   5  * The contents of this file are subject to the Mozilla Public License Version
   6  * 1.1 (the "License"); you may not use this file except in compliance with
   7  * the License. You may obtain a copy of the License at
   8  * http://www.mozilla.org/MPL/
   9  *
  10  * Software distributed under the License is distributed on an "AS IS" basis,
  11  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  12  * for the specific language governing rights and limitations under the
  13  * License.
  14  *
  15  * The Original Code is Widget code.
  16  *
  17  * The Initial Developer of the Original Code is Google Inc.
  18  * Portions created by the Initial Developer are Copyright (C) 2006
  19  * the Initial Developer. All Rights Reserved.
  20  *
  21  * Contributor(s):
  22  *   Darin Fisher <darin@meer.net> (original author)
  23  *
  24  * Alternatively, the contents of this file may be used under the terms of
  25  * either the GNU General Public License Version 2 or later (the "GPL"), or
  26  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  27  * in which case the provisions of the GPL or the LGPL are applicable instead
  28  * of those above. If you wish to allow use of your version of this file only
  29  * under the terms of either the GPL or the LGPL, and not to allow others to
  30  * use your version of this file under the terms of the MPL, indicate your
  31  * decision by deleting the provisions above and replace them with the notice
  32  * and other provisions required by the GPL or the LGPL. If you do not delete
  33  * the provisions above, a recipient may use your version of this file under
  34  * the terms of any one of the MPL, the GPL or the LGPL.
  35  *
  36  * ***** END LICENSE BLOCK ***** */
  37
  38 #ifndef nsBaseAppShell_h__
  39 #define nsBaseAppShell_h__
  40
  41 #include "nsIAppShell.h"
  42 #include "nsIThreadInternal.h"
  43 #include "nsIObserver.h"
  44 #include "nsIRunnable.h"
  45 #include "nsCOMPtr.h"
  46 #include "prinrval.h"
  47
  48 /**
  49  * A singleton that manages the UI thread's event queue.  Subclass this class
  50  * to enable platform-specific event queue support.
  51  */
  52 class nsBaseAppShell : public nsIAppShell, public nsIThreadObserver,
  53                        public nsIObserver
  54 {
  55 public:
  56   NS_DECL_ISUPPORTS
  57   NS_DECL_NSIAPPSHELL
  58   NS_DECL_NSITHREADOBSERVER
  59   NS_DECL_NSIOBSERVER
  60
  61   nsBaseAppShell();
  62
  63 protected:
  64   virtual ~nsBaseAppShell() {}
  65
  66   /**
  67    * This method is called by subclasses when the app shell singleton is
  68    * instantiated.
  69    */
  70   nsresult Init();
  71
  72   /**
  73    * Called by subclasses from a native event. See ScheduleNativeEventCallback.
  74    */
  75   void NativeEventCallback();
  76
  77   /**
  78    * Implemented by subclasses.  Invoke NativeEventCallback from a native
  79    * event.  This method may be called on any thread.
  80    */
  81   virtual void ScheduleNativeEventCallback() = 0;
  82
  83   /**
  84    * Implemented by subclasses.  Process the next native event.  Only wait for
  85    * the next native event if mayWait is true.  This method is only called on
  86    * the main application thread.
  87    *
  88    * @param mayWait
  89    *   If "true", then this method may wait if necessary for the next available
  90    *   native event.  DispatchNativeEvent may be called to unblock a call to
  91    *   ProcessNextNativeEvent that is waiting.
  92    * @return
  93    *   This method returns "true" if a native event was processed.
  94    */
  95   virtual PRBool ProcessNextNativeEvent(PRBool mayWait) = 0;
  96
  97   PRInt32 mSuspendNativeCount;
  98
  99 private:
 100   PRBool DoProcessNextNativeEvent(PRBool mayWait);
 101
 102   nsCOMPtr<nsIRunnable> mDummyEvent;
 103   /**
 104    * mBlockedWait points back to a slot that controls the wait loop in
 105    * an outer OnProcessNextEvent invocation.  Nested calls always set
 106    * it to PR_FALSE to unblock an outer loop, since all events may
 107    * have been consumed by the inner event loop(s).
 108    */
 109   PRBool *mBlockedWait;
 110   PRInt32 mFavorPerf;
 111   PRInt32 mNativeEventPending;
 112   PRUint32 mEventloopNestingLevel;
 113   PRIntervalTime mStarvationDelay;
 114   PRIntervalTime mSwitchTime;
 115   PRIntervalTime mLastNativeEventTime;
 116   enum EventloopNestingState {
 117     eEventloopNone,  // top level thread execution
 118     eEventloopXPCOM, // innermost native event loop is ProcessNextNativeEvent
 119     eEventloopOther  // innermost native event loop is a native library/plugin etc
 120   };
 121   EventloopNestingState mEventloopNestingState;
 122   PRPackedBool mRunWasCalled;
 123   PRPackedBool mExiting;
 124   /**
 125    * mBlockNativeEvent blocks the appshell from processing native events.
 126    * It is set to PR_TRUE while a nested native event loop (eEventloopOther)
 127    * is processing gecko events in NativeEventCallback(), thus queuing up
 128    * native events until we return to that loop (bug 420148).
 129    * We force mBlockNativeEvent to PR_FALSE in case handling one of the gecko
 130    * events spins up a nested XPCOM event loop (eg. modal window) which would
 131    * otherwise lead to a "deadlock" where native events aren't processed at all.
 132    */
 133   PRPackedBool mBlockNativeEvent;
 134 };
 135
 136 #endif // nsBaseAppShell_h__