accessible/src/base/EventQueue.cpp@97036ab72558
accessible/src/base/EventQueue.cpp
Tue, 06 Jan 2015 21:39:09 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Tue, 06 Jan 2015 21:39:09 +0100
- branch
- TOR_BUG_9701
- changeset 8
- 97036ab72558
- permissions
- -rw-r--r--
Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.
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/. */
6 #include "EventQueue.h"
8 #include "Accessible-inl.h"
9 #include "nsEventShell.h"
10 #include "DocAccessible.h"
11 #include "nsAccessibilityService.h"
12 #include "nsTextEquivUtils.h"
13 #ifdef A11Y_LOG
14 #include "Logging.h"
15 #endif
17 using namespace mozilla;
18 using namespace mozilla::a11y;
20 // Defines the number of selection add/remove events in the queue when they
21 // aren't packed into single selection within event.
22 const unsigned int kSelChangeCountToPack = 5;
24 ////////////////////////////////////////////////////////////////////////////////
25 // EventQueue
26 ////////////////////////////////////////////////////////////////////////////////
28 bool
29 EventQueue::PushEvent(AccEvent* aEvent)
30 {
31 NS_ASSERTION((aEvent->mAccessible && aEvent->mAccessible->IsApplication()) ||
32 aEvent->GetDocAccessible() == mDocument,
33 "Queued event belongs to another document!");
35 if (!mEvents.AppendElement(aEvent))
36 return false;
38 // Filter events.
39 CoalesceEvents();
41 // Fire name change event on parent given that this event hasn't been
42 // coalesced, the parent's name was calculated from its subtree, and the
43 // subtree was changed.
44 Accessible* target = aEvent->mAccessible;
45 if (aEvent->mEventRule != AccEvent::eDoNotEmit &&
46 target->HasNameDependentParent() &&
47 (aEvent->mEventType == nsIAccessibleEvent::EVENT_NAME_CHANGE ||
48 aEvent->mEventType == nsIAccessibleEvent::EVENT_TEXT_REMOVED ||
49 aEvent->mEventType == nsIAccessibleEvent::EVENT_TEXT_INSERTED ||
50 aEvent->mEventType == nsIAccessibleEvent::EVENT_SHOW ||
51 aEvent->mEventType == nsIAccessibleEvent::EVENT_HIDE)) {
52 // Only continue traversing up the tree if it's possible that the parent
53 // accessible's name can depend on this accessible's name.
54 Accessible* parent = target->Parent();
55 while (parent &&
56 nsTextEquivUtils::HasNameRule(parent, eNameFromSubtreeIfReqRule)) {
57 // Test possible name dependent parent.
58 if (nsTextEquivUtils::HasNameRule(parent, eNameFromSubtreeRule)) {
59 nsAutoString name;
60 ENameValueFlag nameFlag = parent->Name(name);
61 // If name is obtained from subtree, fire name change event.
62 if (nameFlag == eNameFromSubtree) {
63 nsRefPtr<AccEvent> nameChangeEvent =
64 new AccEvent(nsIAccessibleEvent::EVENT_NAME_CHANGE, parent);
65 PushEvent(nameChangeEvent);
66 }
67 break;
68 }
69 parent = parent->Parent();
70 }
71 }
73 // Associate text change with hide event if it wasn't stolen from hiding
74 // siblings during coalescence.
75 AccMutationEvent* showOrHideEvent = downcast_accEvent(aEvent);
76 if (showOrHideEvent && !showOrHideEvent->mTextChangeEvent)
77 CreateTextChangeEventFor(showOrHideEvent);
79 return true;
80 }
82 ////////////////////////////////////////////////////////////////////////////////
83 // EventQueue: private
85 void
86 EventQueue::CoalesceEvents()
87 {
88 NS_ASSERTION(mEvents.Length(), "There should be at least one pending event!");
89 uint32_t tail = mEvents.Length() - 1;
90 AccEvent* tailEvent = mEvents[tail];
92 switch(tailEvent->mEventRule) {
93 case AccEvent::eCoalesceReorder:
94 CoalesceReorderEvents(tailEvent);
95 break; // case eCoalesceReorder
97 case AccEvent::eCoalesceMutationTextChange:
98 {
99 for (uint32_t index = tail - 1; index < tail; index--) {
100 AccEvent* thisEvent = mEvents[index];
101 if (thisEvent->mEventRule != tailEvent->mEventRule)
102 continue;
104 // We don't currently coalesce text change events from show/hide events.
105 if (thisEvent->mEventType != tailEvent->mEventType)
106 continue;
108 // Show events may be duped because of reinsertion (removal is ignored
109 // because initial insertion is not processed). Ignore initial
110 // insertion.
111 if (thisEvent->mAccessible == tailEvent->mAccessible)
112 thisEvent->mEventRule = AccEvent::eDoNotEmit;
114 AccMutationEvent* tailMutationEvent = downcast_accEvent(tailEvent);
115 AccMutationEvent* thisMutationEvent = downcast_accEvent(thisEvent);
116 if (tailMutationEvent->mParent != thisMutationEvent->mParent)
117 continue;
119 // Coalesce text change events for hide and show events.
120 if (thisMutationEvent->IsHide()) {
121 AccHideEvent* tailHideEvent = downcast_accEvent(tailEvent);
122 AccHideEvent* thisHideEvent = downcast_accEvent(thisEvent);
123 CoalesceTextChangeEventsFor(tailHideEvent, thisHideEvent);
124 break;
125 }
127 AccShowEvent* tailShowEvent = downcast_accEvent(tailEvent);
128 AccShowEvent* thisShowEvent = downcast_accEvent(thisEvent);
129 CoalesceTextChangeEventsFor(tailShowEvent, thisShowEvent);
130 break;
131 }
132 } break; // case eCoalesceMutationTextChange
134 case AccEvent::eCoalesceOfSameType:
135 {
136 // Coalesce old events by newer event.
137 for (uint32_t index = tail - 1; index < tail; index--) {
138 AccEvent* accEvent = mEvents[index];
139 if (accEvent->mEventType == tailEvent->mEventType &&
140 accEvent->mEventRule == tailEvent->mEventRule) {
141 accEvent->mEventRule = AccEvent::eDoNotEmit;
142 return;
143 }
144 }
145 } break; // case eCoalesceOfSameType
147 case AccEvent::eCoalesceSelectionChange:
148 {
149 AccSelChangeEvent* tailSelChangeEvent = downcast_accEvent(tailEvent);
150 for (uint32_t index = tail - 1; index < tail; index--) {
151 AccEvent* thisEvent = mEvents[index];
152 if (thisEvent->mEventRule == tailEvent->mEventRule) {
153 AccSelChangeEvent* thisSelChangeEvent =
154 downcast_accEvent(thisEvent);
156 // Coalesce selection change events within same control.
157 if (tailSelChangeEvent->mWidget == thisSelChangeEvent->mWidget) {
158 CoalesceSelChangeEvents(tailSelChangeEvent, thisSelChangeEvent, index);
159 return;
160 }
161 }
162 }
164 } break; // eCoalesceSelectionChange
166 case AccEvent::eCoalesceStateChange:
167 {
168 // If state change event is duped then ignore previous event. If state
169 // change event is opposite to previous event then no event is emitted
170 // (accessible state wasn't changed).
171 for (uint32_t index = tail - 1; index < tail; index--) {
172 AccEvent* thisEvent = mEvents[index];
173 if (thisEvent->mEventRule != AccEvent::eDoNotEmit &&
174 thisEvent->mEventType == tailEvent->mEventType &&
175 thisEvent->mAccessible == tailEvent->mAccessible) {
176 AccStateChangeEvent* thisSCEvent = downcast_accEvent(thisEvent);
177 AccStateChangeEvent* tailSCEvent = downcast_accEvent(tailEvent);
178 if (thisSCEvent->mState == tailSCEvent->mState) {
179 thisEvent->mEventRule = AccEvent::eDoNotEmit;
180 if (thisSCEvent->mIsEnabled != tailSCEvent->mIsEnabled)
181 tailEvent->mEventRule = AccEvent::eDoNotEmit;
182 }
183 }
184 }
185 break; // eCoalesceStateChange
186 }
188 case AccEvent::eCoalesceTextSelChange:
189 {
190 // Coalesce older event by newer event for the same selection or target.
191 // Events for same selection may have different targets and vice versa one
192 // target may be pointed by different selections (for latter see
193 // bug 927159).
194 for (uint32_t index = tail - 1; index < tail; index--) {
195 AccEvent* thisEvent = mEvents[index];
196 if (thisEvent->mEventRule != AccEvent::eDoNotEmit &&
197 thisEvent->mEventType == tailEvent->mEventType) {
198 AccTextSelChangeEvent* thisTSCEvent = downcast_accEvent(thisEvent);
199 AccTextSelChangeEvent* tailTSCEvent = downcast_accEvent(tailEvent);
200 if (thisTSCEvent->mSel == tailTSCEvent->mSel ||
201 thisEvent->mAccessible == tailEvent->mAccessible)
202 thisEvent->mEventRule = AccEvent::eDoNotEmit;
203 }
205 }
206 } break; // eCoalesceTextSelChange
208 case AccEvent::eRemoveDupes:
209 {
210 // Check for repeat events, coalesce newly appended event by more older
211 // event.
212 for (uint32_t index = tail - 1; index < tail; index--) {
213 AccEvent* accEvent = mEvents[index];
214 if (accEvent->mEventType == tailEvent->mEventType &&
215 accEvent->mEventRule == tailEvent->mEventRule &&
216 accEvent->mAccessible == tailEvent->mAccessible) {
217 tailEvent->mEventRule = AccEvent::eDoNotEmit;
218 return;
219 }
220 }
221 } break; // case eRemoveDupes
223 default:
224 break; // case eAllowDupes, eDoNotEmit
225 } // switch
226 }
228 void
229 EventQueue::CoalesceReorderEvents(AccEvent* aTailEvent)
230 {
231 uint32_t count = mEvents.Length();
232 for (uint32_t index = count - 2; index < count; index--) {
233 AccEvent* thisEvent = mEvents[index];
235 // Skip events of different types and targeted to application accessible.
236 if (thisEvent->mEventType != aTailEvent->mEventType ||
237 thisEvent->mAccessible->IsApplication())
238 continue;
240 // If thisEvent target is not in document longer, i.e. if it was
241 // removed from the tree then do not emit the event.
242 if (!thisEvent->mAccessible->IsDoc() &&
243 !thisEvent->mAccessible->IsInDocument()) {
244 thisEvent->mEventRule = AccEvent::eDoNotEmit;
245 continue;
246 }
248 // Coalesce earlier event of the same target.
249 if (thisEvent->mAccessible == aTailEvent->mAccessible) {
250 if (thisEvent->mEventRule == AccEvent::eDoNotEmit) {
251 AccReorderEvent* tailReorder = downcast_accEvent(aTailEvent);
252 tailReorder->DoNotEmitAll();
253 } else {
254 thisEvent->mEventRule = AccEvent::eDoNotEmit;
255 }
257 return;
258 }
260 // If tailEvent contains thisEvent
261 // then
262 // if show or hide of tailEvent contains a grand parent of thisEvent
263 // then ignore thisEvent and its show and hide events
264 // otherwise ignore thisEvent but not its show and hide events
265 Accessible* thisParent = thisEvent->mAccessible;
266 while (thisParent && thisParent != mDocument) {
267 if (thisParent->Parent() == aTailEvent->mAccessible) {
268 AccReorderEvent* tailReorder = downcast_accEvent(aTailEvent);
269 uint32_t eventType = tailReorder->IsShowHideEventTarget(thisParent);
271 // Sometimes InvalidateChildren() and
272 // DocAccessible::CacheChildrenInSubtree() can conspire to reparent an
273 // accessible in this case no need for mutation events. Se bug 883708
274 // for details.
275 if (eventType == nsIAccessibleEvent::EVENT_SHOW ||
276 eventType == nsIAccessibleEvent::EVENT_HIDE) {
277 AccReorderEvent* thisReorder = downcast_accEvent(thisEvent);
278 thisReorder->DoNotEmitAll();
279 } else {
280 thisEvent->mEventRule = AccEvent::eDoNotEmit;
281 }
283 return;
284 }
286 thisParent = thisParent->Parent();
287 }
289 // If tailEvent is contained by thisEvent
290 // then
291 // if show of thisEvent contains the tailEvent
292 // then ignore tailEvent
293 // if hide of thisEvent contains the tailEvent
294 // then assert
295 // otherwise ignore tailEvent but not its show and hide events
296 Accessible* tailParent = aTailEvent->mAccessible;
297 while (tailParent && tailParent != mDocument) {
298 if (tailParent->Parent() == thisEvent->mAccessible) {
299 AccReorderEvent* thisReorder = downcast_accEvent(thisEvent);
300 AccReorderEvent* tailReorder = downcast_accEvent(aTailEvent);
301 uint32_t eventType = thisReorder->IsShowHideEventTarget(tailParent);
302 if (eventType == nsIAccessibleEvent::EVENT_SHOW)
303 tailReorder->DoNotEmitAll();
304 else if (eventType == nsIAccessibleEvent::EVENT_HIDE)
305 NS_ERROR("Accessible tree was modified after it was removed! Huh?");
306 else
307 aTailEvent->mEventRule = AccEvent::eDoNotEmit;
309 return;
310 }
312 tailParent = tailParent->Parent();
313 }
315 } // for (index)
316 }
318 void
319 EventQueue::CoalesceSelChangeEvents(AccSelChangeEvent* aTailEvent,
320 AccSelChangeEvent* aThisEvent,
321 uint32_t aThisIndex)
322 {
323 aTailEvent->mPreceedingCount = aThisEvent->mPreceedingCount + 1;
325 // Pack all preceding events into single selection within event
326 // when we receive too much selection add/remove events.
327 if (aTailEvent->mPreceedingCount >= kSelChangeCountToPack) {
328 aTailEvent->mEventType = nsIAccessibleEvent::EVENT_SELECTION_WITHIN;
329 aTailEvent->mAccessible = aTailEvent->mWidget;
330 aThisEvent->mEventRule = AccEvent::eDoNotEmit;
332 // Do not emit any preceding selection events for same widget if they
333 // weren't coalesced yet.
334 if (aThisEvent->mEventType != nsIAccessibleEvent::EVENT_SELECTION_WITHIN) {
335 for (uint32_t jdx = aThisIndex - 1; jdx < aThisIndex; jdx--) {
336 AccEvent* prevEvent = mEvents[jdx];
337 if (prevEvent->mEventRule == aTailEvent->mEventRule) {
338 AccSelChangeEvent* prevSelChangeEvent =
339 downcast_accEvent(prevEvent);
340 if (prevSelChangeEvent->mWidget == aTailEvent->mWidget)
341 prevSelChangeEvent->mEventRule = AccEvent::eDoNotEmit;
342 }
343 }
344 }
345 return;
346 }
348 // Pack sequential selection remove and selection add events into
349 // single selection change event.
350 if (aTailEvent->mPreceedingCount == 1 &&
351 aTailEvent->mItem != aThisEvent->mItem) {
352 if (aTailEvent->mSelChangeType == AccSelChangeEvent::eSelectionAdd &&
353 aThisEvent->mSelChangeType == AccSelChangeEvent::eSelectionRemove) {
354 aThisEvent->mEventRule = AccEvent::eDoNotEmit;
355 aTailEvent->mEventType = nsIAccessibleEvent::EVENT_SELECTION;
356 aTailEvent->mPackedEvent = aThisEvent;
357 return;
358 }
360 if (aThisEvent->mSelChangeType == AccSelChangeEvent::eSelectionAdd &&
361 aTailEvent->mSelChangeType == AccSelChangeEvent::eSelectionRemove) {
362 aTailEvent->mEventRule = AccEvent::eDoNotEmit;
363 aThisEvent->mEventType = nsIAccessibleEvent::EVENT_SELECTION;
364 aThisEvent->mPackedEvent = aTailEvent;
365 return;
366 }
367 }
369 // Unpack the packed selection change event because we've got one
370 // more selection add/remove.
371 if (aThisEvent->mEventType == nsIAccessibleEvent::EVENT_SELECTION) {
372 if (aThisEvent->mPackedEvent) {
373 aThisEvent->mPackedEvent->mEventType =
374 aThisEvent->mPackedEvent->mSelChangeType == AccSelChangeEvent::eSelectionAdd ?
375 nsIAccessibleEvent::EVENT_SELECTION_ADD :
376 nsIAccessibleEvent::EVENT_SELECTION_REMOVE;
378 aThisEvent->mPackedEvent->mEventRule =
379 AccEvent::eCoalesceSelectionChange;
381 aThisEvent->mPackedEvent = nullptr;
382 }
384 aThisEvent->mEventType =
385 aThisEvent->mSelChangeType == AccSelChangeEvent::eSelectionAdd ?
386 nsIAccessibleEvent::EVENT_SELECTION_ADD :
387 nsIAccessibleEvent::EVENT_SELECTION_REMOVE;
389 return;
390 }
392 // Convert into selection add since control has single selection but other
393 // selection events for this control are queued.
394 if (aTailEvent->mEventType == nsIAccessibleEvent::EVENT_SELECTION)
395 aTailEvent->mEventType = nsIAccessibleEvent::EVENT_SELECTION_ADD;
396 }
398 void
399 EventQueue::CoalesceTextChangeEventsFor(AccHideEvent* aTailEvent,
400 AccHideEvent* aThisEvent)
401 {
402 // XXX: we need a way to ignore SplitNode and JoinNode() when they do not
403 // affect the text within the hypertext.
405 AccTextChangeEvent* textEvent = aThisEvent->mTextChangeEvent;
406 if (!textEvent)
407 return;
409 if (aThisEvent->mNextSibling == aTailEvent->mAccessible) {
410 aTailEvent->mAccessible->AppendTextTo(textEvent->mModifiedText);
412 } else if (aThisEvent->mPrevSibling == aTailEvent->mAccessible) {
413 uint32_t oldLen = textEvent->GetLength();
414 aTailEvent->mAccessible->AppendTextTo(textEvent->mModifiedText);
415 textEvent->mStart -= textEvent->GetLength() - oldLen;
416 }
418 aTailEvent->mTextChangeEvent.swap(aThisEvent->mTextChangeEvent);
419 }
421 void
422 EventQueue::CoalesceTextChangeEventsFor(AccShowEvent* aTailEvent,
423 AccShowEvent* aThisEvent)
424 {
425 AccTextChangeEvent* textEvent = aThisEvent->mTextChangeEvent;
426 if (!textEvent)
427 return;
429 if (aTailEvent->mAccessible->IndexInParent() ==
430 aThisEvent->mAccessible->IndexInParent() + 1) {
431 // If tail target was inserted after this target, i.e. tail target is next
432 // sibling of this target.
433 aTailEvent->mAccessible->AppendTextTo(textEvent->mModifiedText);
435 } else if (aTailEvent->mAccessible->IndexInParent() ==
436 aThisEvent->mAccessible->IndexInParent() -1) {
437 // If tail target was inserted before this target, i.e. tail target is
438 // previous sibling of this target.
439 nsAutoString startText;
440 aTailEvent->mAccessible->AppendTextTo(startText);
441 textEvent->mModifiedText = startText + textEvent->mModifiedText;
442 textEvent->mStart -= startText.Length();
443 }
445 aTailEvent->mTextChangeEvent.swap(aThisEvent->mTextChangeEvent);
446 }
448 void
449 EventQueue::CreateTextChangeEventFor(AccMutationEvent* aEvent)
450 {
451 Accessible* container = aEvent->mAccessible->Parent();
452 if (!container)
453 return;
455 HyperTextAccessible* textAccessible = container->AsHyperText();
456 if (!textAccessible)
457 return;
459 // Don't fire event for the first html:br in an editor.
460 if (aEvent->mAccessible->Role() == roles::WHITESPACE) {
461 nsCOMPtr<nsIEditor> editor = textAccessible->GetEditor();
462 if (editor) {
463 bool isEmpty = false;
464 editor->GetDocumentIsEmpty(&isEmpty);
465 if (isEmpty)
466 return;
467 }
468 }
470 int32_t offset = textAccessible->GetChildOffset(aEvent->mAccessible);
472 nsAutoString text;
473 aEvent->mAccessible->AppendTextTo(text);
474 if (text.IsEmpty())
475 return;
477 aEvent->mTextChangeEvent =
478 new AccTextChangeEvent(textAccessible, offset, text, aEvent->IsShow(),
479 aEvent->mIsFromUserInput ? eFromUserInput : eNoUserInput);
480 }
482 ////////////////////////////////////////////////////////////////////////////////
483 // EventQueue: event queue
485 void
486 EventQueue::ProcessEventQueue()
487 {
488 // Process only currently queued events.
489 nsTArray<nsRefPtr<AccEvent> > events;
490 events.SwapElements(mEvents);
492 uint32_t eventCount = events.Length();
493 #ifdef A11Y_LOG
494 if (eventCount > 0 && logging::IsEnabled(logging::eEvents)) {
495 logging::MsgBegin("EVENTS", "events processing");
496 logging::Address("document", mDocument);
497 logging::MsgEnd();
498 }
499 #endif
501 for (uint32_t idx = 0; idx < eventCount; idx++) {
502 AccEvent* event = events[idx];
503 if (event->mEventRule != AccEvent::eDoNotEmit) {
504 Accessible* target = event->GetAccessible();
505 if (!target || target->IsDefunct())
506 continue;
508 // Dispatch the focus event if target is still focused.
509 if (event->mEventType == nsIAccessibleEvent::EVENT_FOCUS) {
510 FocusMgr()->ProcessFocusEvent(event);
511 continue;
512 }
514 // Dispatch caret moved and text selection change events.
515 if (event->mEventType == nsIAccessibleEvent::EVENT_TEXT_SELECTION_CHANGED) {
516 SelectionMgr()->ProcessTextSelChangeEvent(event);
517 continue;
518 }
520 // Fire selected state change events in support to selection events.
521 if (event->mEventType == nsIAccessibleEvent::EVENT_SELECTION_ADD) {
522 nsEventShell::FireEvent(event->mAccessible, states::SELECTED,
523 true, event->mIsFromUserInput);
525 } else if (event->mEventType == nsIAccessibleEvent::EVENT_SELECTION_REMOVE) {
526 nsEventShell::FireEvent(event->mAccessible, states::SELECTED,
527 false, event->mIsFromUserInput);
529 } else if (event->mEventType == nsIAccessibleEvent::EVENT_SELECTION) {
530 AccSelChangeEvent* selChangeEvent = downcast_accEvent(event);
531 nsEventShell::FireEvent(event->mAccessible, states::SELECTED,
532 (selChangeEvent->mSelChangeType == AccSelChangeEvent::eSelectionAdd),
533 event->mIsFromUserInput);
535 if (selChangeEvent->mPackedEvent) {
536 nsEventShell::FireEvent(selChangeEvent->mPackedEvent->mAccessible,
537 states::SELECTED,
538 (selChangeEvent->mPackedEvent->mSelChangeType == AccSelChangeEvent::eSelectionAdd),
539 selChangeEvent->mPackedEvent->mIsFromUserInput);
540 }
541 }
543 nsEventShell::FireEvent(event);
545 // Fire text change events.
546 AccMutationEvent* mutationEvent = downcast_accEvent(event);
547 if (mutationEvent) {
548 if (mutationEvent->mTextChangeEvent)
549 nsEventShell::FireEvent(mutationEvent->mTextChangeEvent);
550 }
551 }
553 if (event->mEventType == nsIAccessibleEvent::EVENT_HIDE)
554 mDocument->ShutdownChildrenInSubtree(event->mAccessible);
556 if (!mDocument)
557 return;
558 }
559 }
