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       1             : /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* This Source Code Form is subject to the terms of the Mozilla Public
       3             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       4             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       5             : 
       6             : #ifndef mozilla_a11y_SelectionManager_h__
       7             : #define mozilla_a11y_SelectionManager_h__
       8             : 
       9             : #include "nsIFrame.h"
      10             : #include "nsISelectionListener.h"
      11             : 
      12             : class nsIPresShell;
      13             : 
      14             : namespace mozilla {
      15             : 
      16             : namespace dom {
      17             : class Element;
      18             : }
      19             : 
      20             : namespace a11y {
      21             : 
      22             : class AccEvent;
      23             : class HyperTextAccessible;
      24             : 
      25             : /**
      26             :  * This special accessibility class is for the caret and selection management.
      27             :  * There is only 1 visible caret per top level window. However, there may be
      28             :  * several visible selections.
      29             :  *
      30             :  * The important selections are the one owned by each document, and the one in
      31             :  * the currently focused control.
      32             :  *
      33             :  * On Windows this class is used to move an invisible system caret that
      34             :  * shadows the Mozilla caret. Windows will also automatically map this to
      35             :  * the MSAA caret accessible object (via OBJID_CARET) (as opposed to the root
      36             :  * accessible tree for a window which is retrieved with OBJID_CLIENT).
      37             :  *
      38             :  * For ATK and IAccessible2, this class is used to fire caret move and
      39             :  * selection change events.
      40             :  */
      41             : 
      42             : struct SelData;
      43             : 
      44           0 : class SelectionManager : public nsISelectionListener
      45             : {
      46             : public:
      47             :   // nsISupports
      48             :   // implemented by derived nsAccessibilityService
      49             : 
      50             :   // nsISelectionListener
      51             :   NS_DECL_NSISELECTIONLISTENER
      52             : 
      53             :   // SelectionManager
      54           0 :   void Shutdown() { ClearControlSelectionListener(); }
      55             : 
      56             :   /**
      57             :    * Listen to selection events on the focused control.
      58             :    *
      59             :    * Note: only one control's selection events are listened to at a time. This
      60             :    * will remove the previous control's selection listener.
      61             :    */
      62             :   void SetControlSelectionListener(dom::Element* aFocusedElm);
      63             : 
      64             :   /**
      65             :    * Stop listening to selection events on the control.
      66             :    */
      67             :   void ClearControlSelectionListener();
      68             : 
      69             :   /**
      70             :    * Listen to selection events on the document.
      71             :    */
      72             :   void AddDocSelectionListener(nsIPresShell* aPresShell);
      73             : 
      74             :   /**
      75             :    * Stop listening to selection events for a given document
      76             :    */
      77             :   void RemoveDocSelectionListener(nsIPresShell* aShell);
      78             : 
      79             :   /**
      80             :    * Process delayed event, results in caret move and text selection change
      81             :    * events.
      82             :    */
      83             :   void ProcessTextSelChangeEvent(AccEvent* aEvent);
      84             : 
      85             :   /**
      86             :    * Gets the current caret offset/hypertext accessible pair. If there is no
      87             :    * current pair, then returns -1 for the offset and a nullptr for the
      88             :    * accessible.
      89             :    */
      90           0 :   inline HyperTextAccessible* AccessibleWithCaret(int32_t* aCaret)
      91             :   {
      92           0 :     if (aCaret)
      93           0 :       *aCaret = mCaretOffset;
      94             : 
      95           0 :     return mAccWithCaret;
      96             :   }
      97             : 
      98             :   /**
      99             :    * Update caret offset when it doesn't go through a caret move event.
     100             :    */
     101           0 :   inline void UpdateCaretOffset(HyperTextAccessible* aItem, int32_t aOffset)
     102             :   {
     103           0 :     mAccWithCaret = aItem;
     104           0 :     mCaretOffset = aOffset;
     105           0 :   }
     106             : 
     107           0 :   inline void ResetCaretOffset()
     108             :   {
     109           0 :     mCaretOffset = -1;
     110           0 :     mAccWithCaret = nullptr;
     111           0 :   }
     112             : 
     113             : protected:
     114             : 
     115             :   SelectionManager();
     116             : 
     117             :   /**
     118             :    * Process DOM selection change. Fire selection and caret move events.
     119             :    */
     120             :   void ProcessSelectionChanged(SelData* aSelData);
     121             : 
     122             : private:
     123             :   // Currently focused control.
     124             :   WeakFrame mCurrCtrlFrame;
     125             :   int32_t mCaretOffset;
     126             :   HyperTextAccessible* mAccWithCaret;
     127             : };
     128             : 
     129             : } // namespace a11y
     130             : } // namespace mozilla
     131             : 
     132             : #endif