accessible/base/EventTree.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_EventTree_h_
   7 #define mozilla_a11y_EventTree_h_
   8
   9 #include "AccEvent.h"
  10 #include "LocalAccessible.h"
  11
  12 #include "mozilla/a11y/DocAccessible.h"
  13 #include "mozilla/RefPtr.h"
  14 #include "mozilla/UniquePtr.h"
  15
  16 namespace mozilla {
  17 namespace a11y {
  18
  19 class NotificationController;
  20
  21 /**
  22  * This class makes sure required tasks are done before and after tree
  23  * mutations. Currently this only includes group info invalidation. You must
  24  * have an object of this class on the stack when calling methods that mutate
  25  * the accessible tree.
  26  */
  27 class TreeMutation final {
  28  public:
  29   static const bool kNoEvents = true;
  30   static const bool kNoShutdown = true;
  31
  32   explicit TreeMutation(LocalAccessible* aParent, bool aNoEvents = false);
  33   ~TreeMutation();
  34
  35   void AfterInsertion(LocalAccessible* aChild);
  36   void BeforeRemoval(LocalAccessible* aChild, bool aNoShutdown = false);
  37   void Done();
  38
  39  private:
  40   NotificationController* Controller() const {
  41     return mParent->Document()->Controller();
  42   }
  43
  44   static EventTree* const kNoEventTree;
  45
  46 #ifdef A11Y_LOG
  47   static const char* PrefixLog(void* aData, LocalAccessible*);
  48 #endif
  49
  50   LocalAccessible* mParent;
  51   uint32_t mStartIdx;
  52   uint32_t mStateFlagsCopy;
  53
  54   /*
  55    * True if mutation events should be queued.
  56    */
  57   bool mQueueEvents;
  58
  59 #ifdef DEBUG
  60   bool mIsDone;
  61 #endif
  62 };
  63
  64 /**
  65  * A mutation events coalescence structure.
  66  */
  67 class EventTree final {
  68  public:
  69   EventTree()
  70       : mFirst(nullptr),
  71         mNext(nullptr),
  72         mContainer(nullptr),
  73         mFireReorder(false) {}
  74   explicit EventTree(LocalAccessible* aContainer, bool aFireReorder)
  75       : mFirst(nullptr),
  76         mNext(nullptr),
  77         mContainer(aContainer),
  78         mFireReorder(aFireReorder) {}
  79   ~EventTree() { Clear(); }
  80
  81   void Shown(LocalAccessible* aTarget);
  82   void Hidden(LocalAccessible*, bool);
  83
  84   /**
  85    * Return an event tree node for the given accessible.
  86    */
  87   const EventTree* Find(const LocalAccessible* aContainer) const;
  88
  89   /**
  90    * Add a mutation event to this event tree.
  91    */
  92   void Mutated(AccMutationEvent* aEv);
  93
  94 #ifdef A11Y_LOG
  95   void Log(uint32_t aLevel = UINT32_MAX) const;
  96 #endif
  97
  98  private:
  99   /**
 100    * Processes the event queue and fires events.
 101    */
 102   void Process(const RefPtr<DocAccessible>& aDeathGrip);
 103
 104   /**
 105    * Return an event subtree for the given accessible.
 106    */
 107   EventTree* FindOrInsert(LocalAccessible* aContainer);
 108
 109   void Clear();
 110
 111   UniquePtr<EventTree> mFirst;
 112   UniquePtr<EventTree> mNext;
 113
 114   LocalAccessible* mContainer;
 115   nsTArray<RefPtr<AccMutationEvent>> mDependentEvents;
 116   bool mFireReorder;
 117
 118   static NotificationController* Controller(LocalAccessible* aAcc) {
 119     return aAcc->Document()->Controller();
 120   }
 121
 122   friend class NotificationController;
 123 };
 124
 125 }  // namespace a11y
 126 }  // namespace mozilla
 127
 128 #endif  // mozilla_a11y_EventQueue_h_