accessible/base/EventQueue.h

   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
  11 namespace mozilla {
  12 namespace a11y {
  13
  14 class DocAccessible;
  15
  16 /**
  17  * Used to organize and coalesce pending events.
  18  */
  19 class EventQueue
  20 {
  21 protected:
  22   EventQueue(DocAccessible* aDocument) : mDocument(aDocument) { }
  23
  24   /**
  25    * Put an accessible event into the queue to process it later.
  26    */
  27   bool PushEvent(AccEvent* aEvent);
  28
  29   /**
  30    * Process events from the queue and fires events.
  31    */
  32   void ProcessEventQueue();
  33
  34 private:
  35   EventQueue(const EventQueue&) MOZ_DELETE;
  36   EventQueue& operator = (const EventQueue&) MOZ_DELETE;
  37
  38   // Event queue processing
  39   /**
  40    * Coalesce redundant events from the queue.
  41    */
  42   void CoalesceEvents();
  43
  44   /**
  45    * Coalesce events from the same subtree.
  46    */
  47   void CoalesceReorderEvents(AccEvent* aTailEvent);
  48
  49   /**
  50    * Coalesce two selection change events within the same select control.
  51    */
  52   void CoalesceSelChangeEvents(AccSelChangeEvent* aTailEvent,
  53                                AccSelChangeEvent* aThisEvent,
  54                                uint32_t aThisIndex);
  55
  56   /**
  57    * Coalesce text change events caused by sibling hide events.
  58    */
  59   void CoalesceTextChangeEventsFor(AccHideEvent* aTailEvent,
  60                                    AccHideEvent* aThisEvent);
  61   void CoalesceTextChangeEventsFor(AccShowEvent* aTailEvent,
  62                                    AccShowEvent* aThisEvent);
  63
  64   /**
  65     * Create text change event caused by hide or show event. When a node is
  66     * hidden/removed or shown/appended, the text in an ancestor hyper text will
  67     * lose or get new characters.
  68     */
  69    void CreateTextChangeEventFor(AccMutationEvent* aEvent);
  70
  71 protected:
  72
  73   /**
  74    * The document accessible reference owning this queue.
  75    */
  76   DocAccessible* mDocument;
  77
  78   /**
  79    * Pending events array. Don't make this an nsAutoTArray; we use
  80    * SwapElements() on it.
  81    */
  82   nsTArray<nsRefPtr<AccEvent> > mEvents;
  83 };
  84
  85 } // namespace a11y
  86 } // namespace mozilla
  87
  88 #endif // mozilla_a11y_EventQueue_h_