accessible/src/base/nsCaretAccessible.h

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   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 mozilla.org code.
  16  *
  17  * The Initial Developer of the Original Code is
  18  * Netscape Communications Corporation.
  19  * Portions created by the Initial Developer are Copyright (C) 1998
  20  * the Initial Developer. All Rights Reserved.
  21  *
  22  * Contributor(s):
  23  *
  24  * Alternatively, the contents of this file may be used under the terms of
  25  * either of the GNU General Public License Version 2 or later (the "GPL"),
  26  * or 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 __nsCaretAccessible_h__
  39 #define __nsCaretAccessible_h__
  40
  41 #include "nsIWeakReference.h"
  42 #include "nsIAccessibleText.h"
  43 #include "nsIDOMNode.h"
  44 #include "nsISelectionListener.h"
  45 #include "nsISelectionController.h"
  46 #include "nsRect.h"
  47
  48 class nsRootAccessible;
  49 class nsIView;
  50 class nsIPresShell;
  51 class nsIWidget;
  52
  53 /*
  54  * This special accessibility class is for the caret, which is really the currently focused selection.
  55  * There is only 1 visible caret per top level window (nsRootAccessible),
  56  * However, there may be several visible selections.
  57  *
  58  * The important selections are the one owned by each document, and the one in the currently focused control.
  59  *
  60  * The caret accessible is no longer an accessible object in its own right.
  61  * On Windows it is used to move an invisible system caret that shadows the Mozilla caret. Windows will
  62  * also automatically map this to the MSAA caret accessible object (via OBJID_CARET).
  63  * (as opposed to the root accessible tree for a window which is retrieved with OBJID_CLIENT)
  64  * For ATK and Iaccessible2, the caret accessible is used to fire
  65  * caret move and selection change events.
  66  *
  67  * The caret accessible is owned by the nsRootAccessible for the top level window that it's in.
  68  * The nsRootAccessible needs to tell the nsCaretAccessible about focus changes via
  69  * setControlSelectionListener().
  70  * Each nsDocAccessible needs to tell the nsCaretAccessible owned by the root to
  71  * listen for selection events via addDocSelectionListener() and then needs to remove the
  72  * selection listener when the doc goes away via removeDocSelectionListener().
  73  */
  74
  75 class nsCaretAccessible : public nsISelectionListener
  76 {
  77 public:
  78   NS_DECL_ISUPPORTS
  79
  80   nsCaretAccessible(nsRootAccessible *aRootAccessible);
  81   virtual ~nsCaretAccessible();
  82   void Shutdown();
  83
  84   /* ----- nsISelectionListener ---- */
  85   NS_DECL_NSISELECTIONLISTENER
  86
  87   /**
  88    * Listen to selection events on the focused control.
  89    * Only one control's selection events are listened to at a time, per top-level window.
  90    * This will remove the previous control's selection listener.
  91    * It will fail if aFocusedNode is a document node -- document selection must be listened
  92    * to via AddDocSelectionListener().
  93    * @param aFocusedNode   The node for the focused control
  94    */
  95   nsresult SetControlSelectionListener(nsIDOMNode *aCurrentNode);
  96
  97   /**
  98    * Stop listening to selection events for any control.
  99    * This does not have to be called explicitly in Shutdown() procedures,
 100    * because the nsCaretAccessible implementation guarantees that.
 101    */
 102   nsresult ClearControlSelectionListener();
 103
 104   /**
 105    * Start listening to selection events for a given document
 106    * More than one document's selection events can be listened to
 107    * at the same time, by a given nsCaretAccessible
 108    * @param aShell   PresShell for document to listen to selection events from.
 109    */
 110   nsresult AddDocSelectionListener(nsIPresShell *aShell);
 111
 112   /**
 113    * Stop listening to selection events for a given document
 114    * If the document goes away, this method needs to be called for
 115    * that document by the owner of the caret. We use presShell because
 116    * instead of document because it is more direct than getting it from
 117    * the document, and in any case it is unavailable from the doc after a pagehide.
 118    * @param aShell   PresShell for document to no longer listen to selection events from.
 119    */
 120   nsresult RemoveDocSelectionListener(nsIPresShell *aShell);
 121
 122   nsRect GetCaretRect(nsIWidget **aOutWidget);
 123
 124 protected:
 125   nsresult NormalSelectionChanged(nsIDOMDocument *aDoc, nsISelection *aSel);
 126   nsresult SpellcheckSelectionChanged(nsIDOMDocument *aDoc, nsISelection *aSel);
 127
 128   already_AddRefed<nsISelectionController>
 129   GetSelectionControllerForNode(nsIDOMNode *aNode);
 130
 131 private:
 132   // The currently focused control -- never a document.
 133   // We listen to selection for one control at a time (the focused one)
 134   // Document selection is handled separately via additional listeners on all active documents
 135   // The current control is set via SetControlSelectionListener()
 136   nsCOMPtr<nsIDOMNode> mCurrentControl;  // Selection controller for the currently focused control
 137
 138   // Info for the the last selection event.
 139   // If it was on a control, then its control's selection. Otherwise, it's for
 140   // a document where the selection changed.
 141   nsCOMPtr<nsIWeakReference> mLastUsedSelection; // Weak ref to nsISelection
 142   nsCOMPtr<nsIAccessibleText> mLastTextAccessible;
 143   PRInt32 mLastCaretOffset;
 144
 145   nsRootAccessible *mRootAccessible;
 146 };
 147
 148 #endif