tor-browser

The Tor Browser
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EventQueue.h (2234B)

      1 /* -*- Mode: C++; tab-width: 2; 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_EventQueue_h_
      7 #define mozilla_a11y_EventQueue_h_
      8 
      9 #include "AccEvent.h"
     10 #include "mozilla/Assertions.h"
     11 
     12 namespace mozilla {
     13 namespace a11y {
     14 
     15 class DocAccessible;
     16 
     17 /**
     18 * Used to organize and coalesce pending events.
     19 */
     20 class EventQueue {
     21 protected:
     22  explicit EventQueue(DocAccessible* aDocument) : mDocument(aDocument) {
     23    MOZ_ASSERT(mDocument,
     24               "There's no point creating an event queue for a null document");
     25  }
     26 
     27  /**
     28   * Put an accessible event into the queue to process it later.
     29   */
     30  bool PushEvent(AccEvent* aEvent);
     31 
     32  bool PushNameOrDescriptionChangeToRelations(LocalAccessible* aAccessible,
     33                                              RelationType aType);
     34 
     35  /**
     36   * Puts name and/or description change events into the queue, if needed.
     37   */
     38  bool PushNameOrDescriptionChange(AccEvent* aOrigEvent);
     39 
     40  /**
     41   * Process events from the queue and fires events.
     42   */
     43  void ProcessEventQueue();
     44 
     45 private:
     46  EventQueue(const EventQueue&) = delete;
     47  EventQueue& operator=(const EventQueue&) = delete;
     48 
     49  // Event queue processing
     50  /**
     51   * Coalesce redundant events from the queue.
     52   */
     53  void CoalesceEvents();
     54 
     55  /**
     56   * Coalesce events from the same subtree.
     57   */
     58  void CoalesceReorderEvents(AccEvent* aTailEvent);
     59 
     60  /**
     61   * Coalesce two selection change events within the same select control.
     62   */
     63  void CoalesceSelChangeEvents(AccSelChangeEvent* aTailEvent,
     64                               AccSelChangeEvent* aThisEvent,
     65                               uint32_t aThisIndex);
     66 
     67 protected:
     68  /**
     69   * The document accessible reference owning this queue.
     70   */
     71  DocAccessible* mDocument;
     72 
     73  /**
     74   * Pending events array. Don't make this an AutoTArray; we use
     75   * SwapElements() on it.
     76   */
     77  nsTArray<RefPtr<AccEvent>> mEvents;
     78 
     79  // Pending focus event.
     80  RefPtr<AccEvent> mFocusEvent;
     81 };
     82 
     83 }  // namespace a11y
     84 }  // namespace mozilla
     85 
     86 #endif  // mozilla_a11y_EventQueue_h_