accessible/base/SelectionManager.h

   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 "nsISelectionListener.h"
  10 #include "mozilla/WeakPtr.h"
  11
  12 namespace mozilla {
  13
  14 class PresShell;
  15
  16 namespace dom {
  17 class Element;
  18 class Selection;
  19 }  // namespace dom
  20
  21 namespace a11y {
  22
  23 class AccEvent;
  24 class HyperTextAccessible;
  25
  26 /**
  27  * This special accessibility class is for the caret and selection management.
  28  * There is only 1 visible caret per top level window. However, there may be
  29  * several visible selections.
  30  *
  31  * The important selections are the one owned by each document, and the one in
  32  * the currently focused control.
  33  *
  34  * On Windows this class is used to move an invisible system caret that
  35  * shadows the Mozilla caret. Windows will also automatically map this to
  36  * the MSAA caret accessible object (via OBJID_CARET) (as opposed to the root
  37  * accessible tree for a window which is retrieved with OBJID_CLIENT).
  38  *
  39  * For ATK and IAccessible2, this class is used to fire caret move and
  40  * selection change events.
  41  */
  42
  43 struct SelData;
  44
  45 class SelectionManager : public nsISelectionListener {
  46  public:
  47   // nsISupports
  48   // implemented by derived nsAccessibilityService
  49
  50   // nsISelectionListener
  51   NS_DECL_NSISELECTIONLISTENER
  52
  53   // SelectionManager
  54   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(PresShell* aPresShell);
  73
  74   /**
  75    * Stop listening to selection events for a given document
  76    */
  77   void RemoveDocSelectionListener(PresShell* aPresShell);
  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   inline HyperTextAccessible* AccessibleWithCaret(int32_t* aCaret) {
  91     if (aCaret) *aCaret = mCaretOffset;
  92
  93     return mAccWithCaret;
  94   }
  95
  96   /**
  97    * Update caret offset when it doesn't go through a caret move event.
  98    */
  99   inline void UpdateCaretOffset(HyperTextAccessible* aItem, int32_t aOffset) {
 100     mAccWithCaret = aItem;
 101     mCaretOffset = aOffset;
 102   }
 103
 104   inline void ResetCaretOffset() {
 105     mCaretOffset = -1;
 106     mAccWithCaret = nullptr;
 107   }
 108
 109   ~SelectionManager();
 110
 111  protected:
 112   SelectionManager();
 113
 114   /**
 115    * Process DOM selection change. Fire selection and caret move events.
 116    */
 117   void ProcessSelectionChanged(SelData* aSelData);
 118
 119  private:
 120   // Currently focused control.
 121   int32_t mCaretOffset;
 122   HyperTextAccessible* mAccWithCaret;
 123   WeakPtr<dom::Selection> mCurrCtrlNormalSel;
 124   WeakPtr<dom::Selection> mCurrCtrlSpellSel;
 125 };
 126
 127 }  // namespace a11y
 128 }  // namespace mozilla
 129
 130 #endif