summaryrefslogtreecommitdiffstats
path: root/accessible/base/NotificationController.h
blob: bc1a692c23d8599512a5ce956d99998640347c46 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_a11y_NotificationController_h_
#define mozilla_a11y_NotificationController_h_

#include "EventQueue.h"

#include "nsClassHashtable.h"
#include "nsCycleCollectionParticipant.h"
#include "nsIFrame.h"
#include "nsRefreshObservers.h"
#include "nsTHashSet.h"

#include <utility>

#ifdef A11Y_LOG
#  include "Logging.h"
#endif

namespace mozilla {

class PresShell;

namespace a11y {

class DocAccessible;

/**
 * Notification interface.
 */
class Notification {
 public:
  NS_INLINE_DECL_REFCOUNTING(mozilla::a11y::Notification)

  /**
   * Process notification.
   */
  virtual void Process() = 0;

 protected:
  Notification() {}

  /**
   * Protected destructor, to discourage deletion outside of Release():
   */
  virtual ~Notification() {}

 private:
  Notification(const Notification&);
  Notification& operator=(const Notification&);
};

/**
 * Template class for generic notification.
 *
 * @note  Instance is kept as a weak ref, the caller must guarantee it exists
 *        longer than the document accessible owning the notification controller
 *        that this notification is processed by.
 */
template <class Class, class... Args>
class TNotification : public Notification {
 public:
  typedef void (Class::*Callback)(Args*...);

  TNotification(Class* aInstance, Callback aCallback, Args*... aArgs)
      : mInstance(aInstance), mCallback(aCallback), mArgs(aArgs...) {}
  virtual ~TNotification() { mInstance = nullptr; }

  virtual void Process() override {
    ProcessHelper(std::index_sequence_for<Args...>{});
  }

 private:
  TNotification(const TNotification&);
  TNotification& operator=(const TNotification&);

  template <size_t... Indices>
  void ProcessHelper(std::index_sequence<Indices...>) {
    (mInstance->*mCallback)(std::get<Indices>(mArgs)...);
  }

  Class* mInstance;
  Callback mCallback;
  std::tuple<RefPtr<Args>...> mArgs;
};

/**
 * Used to process notifications from core for the document accessible.
 */
class NotificationController final : public EventQueue,
                                     public nsARefreshObserver {
 public:
  NotificationController(DocAccessible* aDocument, PresShell* aPresShell);

  NS_IMETHOD_(MozExternalRefCountType) AddRef(void) override;
  NS_IMETHOD_(MozExternalRefCountType) Release(void) override;

  NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS(NotificationController)

  /**
   * Shutdown the notification controller.
   */
  void Shutdown();

  /**
   * Add an accessible event into the queue to process it later.
   */
  void QueueEvent(AccEvent* aEvent) {
    if (PushEvent(aEvent)) {
      ScheduleProcessing();
    }
  }

  /**
   * Queue a mutation event to emit if not coalesced away.  Returns true if the
   * event was queued and has not yet been coalesced.
   */
  bool QueueMutationEvent(AccTreeMutationEvent* aEvent);

  /**
   * Coalesce all queued mutation events.
   */
  void CoalesceMutationEvents();

  /**
   * Schedule binding the child document to the tree of this document.
   */
  void ScheduleChildDocBinding(DocAccessible* aDocument);

  /**
   * Schedule the accessible tree update because of rendered text changes.
   */
  inline void ScheduleTextUpdate(nsIContent* aTextNode) {
    // Make sure we are not called with a node that is not in the DOM tree or
    // not visible.
    MOZ_ASSERT(aTextNode->GetParentNode(), "A text node is not in DOM");
    MOZ_ASSERT(aTextNode->GetPrimaryFrame(),
               "A text node doesn't have a frame");
    MOZ_ASSERT(aTextNode->GetPrimaryFrame()->StyleVisibility()->IsVisible(),
               "A text node is not visible");

    mTextHash.Insert(aTextNode);

    ScheduleProcessing();
  }

  /**
   * Pend accessible tree update for content insertion.
   */
  void ScheduleContentInsertion(LocalAccessible* aContainer,
                                nsTArray<nsCOMPtr<nsIContent>>& aInsertions);

  /**
   * Pend an accessible subtree relocation.
   */
  void ScheduleRelocation(LocalAccessible* aOwner) {
    if (!mRelocations.Contains(aOwner)) {
      // XXX(Bug 1631371) Check if this should use a fallible operation as it
      // pretended earlier, or change the return type to void.
      mRelocations.AppendElement(aOwner);
      ScheduleProcessing();
    }
  }

  /**
   * Start to observe refresh to make notifications and events processing after
   * layout.
   */
  void ScheduleProcessing();

  /**
   * Process the generic notification synchronously if there are no pending
   * layout changes and no notifications are pending or being processed right
   * now. Otherwise, queue it up to process asynchronously.
   *
   * @note  The caller must guarantee that the given instance still exists when
   *        the notification is processed.
   */
  template <class Class, class... Args>
  inline void HandleNotification(
      Class* aInstance,
      typename TNotification<Class, Args...>::Callback aMethod,
      Args*... aArgs) {
    if (!IsUpdatePending()) {
#ifdef A11Y_LOG
      if (mozilla::a11y::logging::IsEnabled(
              mozilla::a11y::logging::eNotifications)) {
        mozilla::a11y::logging::Text("sync notification processing");
      }
#endif
      (aInstance->*aMethod)(aArgs...);
      return;
    }

    RefPtr<Notification> notification =
        new TNotification<Class, Args...>(aInstance, aMethod, aArgs...);
    if (notification) {
      // XXX(Bug 1631371) Check if this should use a fallible operation as it
      // pretended earlier.
      mNotifications.AppendElement(notification);
      ScheduleProcessing();
    }
  }

  /**
   * Schedule the generic notification to process asynchronously.
   *
   * @note  The caller must guarantee that the given instance still exists when
   *        the notification is processed.
   */
  template <class Class>
  inline void ScheduleNotification(
      Class* aInstance, typename TNotification<Class>::Callback aMethod) {
    RefPtr<Notification> notification =
        new TNotification<Class>(aInstance, aMethod);
    if (notification) {
      // XXX(Bug 1631371) Check if this should use a fallible operation as it
      // pretended earlier.
      mNotifications.AppendElement(notification);
      ScheduleProcessing();
    }
  }

  template <class Class, class Arg>
  inline void ScheduleNotification(
      Class* aInstance, typename TNotification<Class, Arg>::Callback aMethod,
      Arg* aArg) {
    RefPtr<Notification> notification =
        new TNotification<Class, Arg>(aInstance, aMethod, aArg);
    if (notification) {
      // XXX(Bug 1631371) Check if this should use a fallible operation as it
      // pretended earlier.
      mNotifications.AppendElement(notification);
      ScheduleProcessing();
    }
  }

#ifdef DEBUG
  bool IsUpdating() const {
    return mObservingState == eRefreshProcessingForUpdate;
  }
#endif

 protected:
  virtual ~NotificationController();

  nsCycleCollectingAutoRefCnt mRefCnt;
  NS_DECL_OWNINGTHREAD

  /**
   * Return true if the accessible tree state update is pending.
   */
  bool IsUpdatePending();

  /**
   * Return true if we should wait for processing from the parent before we can
   * process our own queue.
   */
  bool WaitingForParent();

 private:
  NotificationController(const NotificationController&);
  NotificationController& operator=(const NotificationController&);

  // nsARefreshObserver
  virtual void WillRefresh(mozilla::TimeStamp aTime) override;

 private:
  /**
   * Remove a specific hide event if it should not be propagated.
   */
  void CoalesceHideEvent(AccHideEvent* aHideEvent);

  /**
   * get rid of a mutation event that is no longer necessary.
   */
  void DropMutationEvent(AccTreeMutationEvent* aEvent);

  /**
   * Fire all necessary mutation events.
   */
  void ProcessMutationEvents();

  /**
   * Indicates whether we're waiting on an event queue processing from our
   * notification controller to flush events.
   */
  enum eObservingState {
    eNotObservingRefresh,
    eRefreshObserving,
    eRefreshProcessing,
    eRefreshProcessingForUpdate
  };
  eObservingState mObservingState;

  /**
   * The presshell of the document accessible.
   */
  PresShell* mPresShell;

  /**
   * Child documents that needs to be bound to the tree.
   */
  nsTArray<RefPtr<DocAccessible>> mHangingChildDocuments;

  /**
   * Pending accessible tree update notifications for content insertions.
   */
  nsClassHashtable<nsRefPtrHashKey<LocalAccessible>,
                   nsTArray<nsCOMPtr<nsIContent>>>
      mContentInsertions;

  template <class T>
  class nsCOMPtrHashKey : public PLDHashEntryHdr {
   public:
    typedef T* KeyType;
    typedef const T* KeyTypePointer;

    explicit nsCOMPtrHashKey(const T* aKey) : mKey(const_cast<T*>(aKey)) {}
    nsCOMPtrHashKey(nsCOMPtrHashKey<T>&& aOther)
        : PLDHashEntryHdr(std::move(aOther)), mKey(std::move(aOther.mKey)) {}
    ~nsCOMPtrHashKey() {}

    KeyType GetKey() const { return mKey; }
    bool KeyEquals(KeyTypePointer aKey) const { return aKey == mKey; }

    static KeyTypePointer KeyToPointer(KeyType aKey) { return aKey; }
    static PLDHashNumber HashKey(KeyTypePointer aKey) {
      return NS_PTR_TO_INT32(aKey) >> 2;
    }

    enum { ALLOW_MEMMOVE = true };

   protected:
    nsCOMPtr<T> mKey;
  };

  /**
   * Pending accessible tree update notifications for rendered text changes.
   */
  nsTHashSet<nsCOMPtrHashKey<nsIContent>> mTextHash;

  /**
   * Other notifications like DOM events. Don't make this an AutoTArray; we
   * use SwapElements() on it.
   */
  nsTArray<RefPtr<Notification>> mNotifications;

  /**
   * Holds all scheduled relocations.
   */
  nsTArray<RefPtr<LocalAccessible>> mRelocations;

  /**
   * A list of all mutation events we may want to emit.  Ordered from the first
   * event that should be emitted to the last one to emit.
   */
  RefPtr<AccTreeMutationEvent> mFirstMutationEvent;
  RefPtr<AccTreeMutationEvent> mLastMutationEvent;

  /**
   * A class to map an accessible and event type to an event.
   */
  class EventMap {
   public:
    enum EventType {
      ShowEvent = 0x0,
      HideEvent = 0x1,
      ReorderEvent = 0x2,
    };

    void PutEvent(AccTreeMutationEvent* aEvent);
    AccTreeMutationEvent* GetEvent(LocalAccessible* aTarget, EventType aType);
    void RemoveEvent(AccTreeMutationEvent* aEvent);
    void Clear() { mTable.Clear(); }

   private:
    EventType GetEventType(AccTreeMutationEvent* aEvent);

    nsRefPtrHashtable<nsUint64HashKey, AccTreeMutationEvent> mTable;
  };

  EventMap mMutationMap;
  uint32_t mEventGeneration;
};

}  // namespace a11y
}  // namespace mozilla

#endif  // mozilla_a11y_NotificationController_h_