gecko-dev/accessible/base/NotificationController.cpp
James Teh 095a80c647 Bug 1897349: Don't update CSS pseudo-element TextLeafAccessibles if there is CSS content alt text. r=eeejay
When we create a TextLeafAccessible for a CSS pseudo-element, we already use the alt text if present.
However, it seems layout sometimes re-renders the text of pseudo-elements.
Previously, a11y would update the text in this case like it would for any other TextLeafAccessible, thus overwriting the alt text with the text rendered by layout.
To fix this, we now skip updating text if CSS alt text is present.

Differential Revision: https://phabricator.services.mozilla.com/D211139
2024-05-22 22:14:33 +00:00

1117 lines
40 KiB
C++

/* -*- 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/. */
#include "NotificationController.h"
#include "CssAltContent.h"
#include "DocAccessible-inl.h"
#include "DocAccessibleChild.h"
#include "LocalAccessible-inl.h"
#include "nsEventShell.h"
#include "TextLeafAccessible.h"
#include "TextUpdater.h"
#include "nsIContentInlines.h"
#include "mozilla/dom/BrowserChild.h"
#include "mozilla/dom/Element.h"
#include "mozilla/ipc/ProcessChild.h"
#include "mozilla/PresShell.h"
#include "mozilla/ProfilerMarkers.h"
#include "nsAccessibilityService.h"
#include "mozilla/Telemetry.h"
using namespace mozilla;
using namespace mozilla::a11y;
using namespace mozilla::dom;
////////////////////////////////////////////////////////////////////////////////
// NotificationCollector
////////////////////////////////////////////////////////////////////////////////
NotificationController::NotificationController(DocAccessible* aDocument,
PresShell* aPresShell)
: EventQueue(aDocument),
mObservingState(eNotObservingRefresh),
mPresShell(aPresShell),
mEventGeneration(0) {
// Schedule initial accessible tree construction.
ScheduleProcessing();
}
NotificationController::~NotificationController() {
NS_ASSERTION(!mDocument, "Controller wasn't shutdown properly!");
if (mDocument) {
Shutdown();
}
MOZ_RELEASE_ASSERT(mObservingState == eNotObservingRefresh,
"Must unregister before being destroyed");
}
////////////////////////////////////////////////////////////////////////////////
// NotificationCollector: AddRef/Release and cycle collection
NS_IMPL_CYCLE_COLLECTING_NATIVE_ADDREF(NotificationController)
NS_IMPL_CYCLE_COLLECTING_NATIVE_RELEASE(NotificationController)
NS_IMPL_CYCLE_COLLECTION_CLASS(NotificationController)
NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(NotificationController)
if (tmp->mDocument) {
tmp->Shutdown();
}
NS_IMPL_CYCLE_COLLECTION_UNLINK_END
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(NotificationController)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mHangingChildDocuments)
for (const auto& entry : tmp->mContentInsertions) {
NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mContentInsertions key");
cb.NoteXPCOMChild(entry.GetKey());
nsTArray<nsCOMPtr<nsIContent>>* list = entry.GetData().get();
for (uint32_t i = 0; i < list->Length(); i++) {
NS_CYCLE_COLLECTION_NOTE_EDGE_NAME(cb, "mContentInsertions value item");
cb.NoteXPCOMChild(list->ElementAt(i));
}
}
NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mFocusEvent)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mEvents)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mRelocations)
NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
////////////////////////////////////////////////////////////////////////////////
// NotificationCollector: public
void NotificationController::Shutdown() {
if (mObservingState != eNotObservingRefresh &&
mPresShell->RemoveRefreshObserver(this, FlushType::Display)) {
// Note, this was our last chance to unregister, since we're about to
// clear mPresShell further down in this function.
mObservingState = eNotObservingRefresh;
}
MOZ_RELEASE_ASSERT(mObservingState == eNotObservingRefresh,
"Must unregister before being destroyed (and we just "
"passed our last change to unregister)");
// Immediately null out mPresShell, to prevent us from being registered as a
// refresh observer again.
mPresShell = nullptr;
// Shutdown handling child documents.
int32_t childDocCount = mHangingChildDocuments.Length();
for (int32_t idx = childDocCount - 1; idx >= 0; idx--) {
if (!mHangingChildDocuments[idx]->IsDefunct()) {
mHangingChildDocuments[idx]->Shutdown();
}
}
mHangingChildDocuments.Clear();
mDocument = nullptr;
mTextArray.Clear();
mContentInsertions.Clear();
mNotifications.Clear();
mFocusEvent = nullptr;
mEvents.Clear();
mRelocations.Clear();
}
void NotificationController::CoalesceHideEvent(AccHideEvent* aHideEvent) {
LocalAccessible* parent = aHideEvent->LocalParent();
while (parent) {
if (parent->IsDoc()) {
break;
}
if (parent->HideEventTarget()) {
DropMutationEvent(aHideEvent);
break;
}
if (parent->ShowEventTarget()) {
AccShowEvent* showEvent =
downcast_accEvent(mMutationMap.GetEvent(parent, EventMap::ShowEvent));
if (showEvent->EventGeneration() < aHideEvent->EventGeneration()) {
DropMutationEvent(aHideEvent);
break;
}
}
parent = parent->LocalParent();
}
}
bool NotificationController::QueueMutationEvent(AccTreeMutationEvent* aEvent) {
if (aEvent->GetEventType() == nsIAccessibleEvent::EVENT_HIDE) {
// We have to allow there to be a hide and then a show event for a target
// because of targets getting moved. However we need to coalesce a show and
// then a hide for a target which means we need to check for that here.
if (aEvent->GetAccessible()->ShowEventTarget()) {
AccTreeMutationEvent* showEvent =
mMutationMap.GetEvent(aEvent->GetAccessible(), EventMap::ShowEvent);
DropMutationEvent(showEvent);
return false;
}
// Don't queue a hide event on an accessible that's already being moved. It
// or an ancestor should already have a hide event queued.
if (mDocument &&
mDocument->IsAccessibleBeingMoved(aEvent->GetAccessible())) {
return false;
}
// If this is an additional hide event, the accessible may be hidden, or
// moved again after a move. Preserve the original hide event since
// its properties are consistent with the tree that existed before
// the next batch of mutation events is processed.
if (aEvent->GetAccessible()->HideEventTarget()) {
return false;
}
}
AccMutationEvent* mutEvent = downcast_accEvent(aEvent);
mEventGeneration++;
mutEvent->SetEventGeneration(mEventGeneration);
if (!mFirstMutationEvent) {
mFirstMutationEvent = aEvent;
ScheduleProcessing();
}
if (mLastMutationEvent) {
NS_ASSERTION(!mLastMutationEvent->NextEvent(),
"why isn't the last event the end?");
mLastMutationEvent->SetNextEvent(aEvent);
}
aEvent->SetPrevEvent(mLastMutationEvent);
mLastMutationEvent = aEvent;
mMutationMap.PutEvent(aEvent);
// Because we could be hiding the target of a show event we need to get rid
// of any such events.
if (aEvent->GetEventType() == nsIAccessibleEvent::EVENT_HIDE) {
CoalesceHideEvent(downcast_accEvent(aEvent));
// mLastMutationEvent will point to something other than aEvent if and only
// if aEvent was just coalesced away. In that case a parent accessible
// must already have the required reorder and text change events so we are
// done here.
if (mLastMutationEvent != aEvent) {
return false;
}
}
// We need to fire a reorder event after all of the events targeted at shown
// or hidden children of a container. So either queue a new one, or move an
// existing one to the end of the queue if the container already has a
// reorder event.
LocalAccessible* container = aEvent->GetAccessible()->LocalParent();
RefPtr<AccReorderEvent> reorder;
if (!container->ReorderEventTarget()) {
reorder = new AccReorderEvent(container);
container->SetReorderEventTarget(true);
mMutationMap.PutEvent(reorder);
// Since this is the first child of container that is changing, the name
// and/or description of dependent Accessibles may be changing.
if (PushNameOrDescriptionChange(aEvent)) {
ScheduleProcessing();
}
} else {
AccReorderEvent* event = downcast_accEvent(
mMutationMap.GetEvent(container, EventMap::ReorderEvent));
reorder = event;
if (mFirstMutationEvent == event) {
mFirstMutationEvent = event->NextEvent();
} else {
event->PrevEvent()->SetNextEvent(event->NextEvent());
}
event->NextEvent()->SetPrevEvent(event->PrevEvent());
event->SetNextEvent(nullptr);
}
reorder->SetEventGeneration(mEventGeneration);
reorder->SetPrevEvent(mLastMutationEvent);
mLastMutationEvent->SetNextEvent(reorder);
mLastMutationEvent = reorder;
// It is not possible to have a text change event for something other than a
// hyper text accessible.
if (!container->IsHyperText()) {
return true;
}
MOZ_ASSERT(mutEvent);
nsString text;
aEvent->GetAccessible()->AppendTextTo(text);
if (text.IsEmpty()) {
return true;
}
LocalAccessible* target = aEvent->GetAccessible();
int32_t offset = container->AsHyperText()->GetChildOffset(target);
AccTreeMutationEvent* prevEvent = aEvent->PrevEvent();
while (prevEvent &&
prevEvent->GetEventType() == nsIAccessibleEvent::EVENT_REORDER) {
prevEvent = prevEvent->PrevEvent();
}
if (prevEvent &&
prevEvent->GetEventType() == nsIAccessibleEvent::EVENT_HIDE &&
mutEvent->IsHide()) {
AccHideEvent* prevHide = downcast_accEvent(prevEvent);
AccTextChangeEvent* prevTextChange = prevHide->mTextChangeEvent;
if (prevTextChange && prevHide->LocalParent() == mutEvent->LocalParent()) {
if (prevHide->mNextSibling == target) {
target->AppendTextTo(prevTextChange->mModifiedText);
prevHide->mTextChangeEvent.swap(mutEvent->mTextChangeEvent);
} else if (prevHide->mPrevSibling == target) {
nsString temp;
target->AppendTextTo(temp);
uint32_t extraLen = temp.Length();
temp += prevTextChange->mModifiedText;
;
prevTextChange->mModifiedText = temp;
prevTextChange->mStart -= extraLen;
prevHide->mTextChangeEvent.swap(mutEvent->mTextChangeEvent);
}
}
} else if (prevEvent && mutEvent->IsShow() &&
prevEvent->GetEventType() == nsIAccessibleEvent::EVENT_SHOW) {
AccShowEvent* prevShow = downcast_accEvent(prevEvent);
AccTextChangeEvent* prevTextChange = prevShow->mTextChangeEvent;
if (prevTextChange && prevShow->LocalParent() == target->LocalParent()) {
int32_t index = target->IndexInParent();
int32_t prevIndex = prevShow->GetAccessible()->IndexInParent();
if (prevIndex + 1 == index) {
target->AppendTextTo(prevTextChange->mModifiedText);
prevShow->mTextChangeEvent.swap(mutEvent->mTextChangeEvent);
} else if (index + 1 == prevIndex) {
nsString temp;
target->AppendTextTo(temp);
prevTextChange->mStart -= temp.Length();
temp += prevTextChange->mModifiedText;
prevTextChange->mModifiedText = temp;
prevShow->mTextChangeEvent.swap(mutEvent->mTextChangeEvent);
}
}
}
if (!mutEvent->mTextChangeEvent) {
mutEvent->mTextChangeEvent = new AccTextChangeEvent(
container, offset, text, mutEvent->IsShow(),
aEvent->mIsFromUserInput ? eFromUserInput : eNoUserInput);
}
return true;
}
void NotificationController::DropMutationEvent(AccTreeMutationEvent* aEvent) {
const uint32_t eventType = aEvent->GetEventType();
MOZ_ASSERT(eventType != nsIAccessibleEvent::EVENT_INNER_REORDER,
"Inner reorder has already been dropped, cannot drop again");
if (eventType == nsIAccessibleEvent::EVENT_REORDER) {
// We don't fully drop reorder events, we just change them to inner reorder
// events.
AccReorderEvent* reorderEvent = downcast_accEvent(aEvent);
MOZ_ASSERT(reorderEvent);
reorderEvent->SetInner();
return;
}
if (eventType == nsIAccessibleEvent::EVENT_SHOW) {
// unset the event bits since the event isn't being fired any more.
aEvent->GetAccessible()->SetShowEventTarget(false);
} else if (eventType == nsIAccessibleEvent::EVENT_HIDE) {
// unset the event bits since the event isn't being fired any more.
aEvent->GetAccessible()->SetHideEventTarget(false);
AccHideEvent* hideEvent = downcast_accEvent(aEvent);
MOZ_ASSERT(hideEvent);
if (hideEvent->NeedsShutdown()) {
mDocument->ShutdownChildrenInSubtree(aEvent->GetAccessible());
}
} else {
MOZ_ASSERT_UNREACHABLE("Mutation event has non-mutation event type");
}
// Do the work to splice the event out of the list.
if (mFirstMutationEvent == aEvent) {
mFirstMutationEvent = aEvent->NextEvent();
} else {
aEvent->PrevEvent()->SetNextEvent(aEvent->NextEvent());
}
if (mLastMutationEvent == aEvent) {
mLastMutationEvent = aEvent->PrevEvent();
} else {
aEvent->NextEvent()->SetPrevEvent(aEvent->PrevEvent());
}
aEvent->SetPrevEvent(nullptr);
aEvent->SetNextEvent(nullptr);
mMutationMap.RemoveEvent(aEvent);
}
void NotificationController::CoalesceMutationEvents() {
AccTreeMutationEvent* event = mFirstMutationEvent;
while (event) {
AccTreeMutationEvent* nextEvent = event->NextEvent();
uint32_t eventType = event->GetEventType();
if (event->GetEventType() == nsIAccessibleEvent::EVENT_REORDER) {
LocalAccessible* acc = event->GetAccessible();
while (acc) {
if (acc->IsDoc()) {
break;
}
// if a parent of the reorder event's target is being hidden that
// hide event's target must have a parent that is also a reorder event
// target. That means we don't need this reorder event.
if (acc->HideEventTarget()) {
DropMutationEvent(event);
break;
}
LocalAccessible* parent = acc->LocalParent();
if (parent && parent->ReorderEventTarget()) {
AccReorderEvent* reorder = downcast_accEvent(
mMutationMap.GetEvent(parent, EventMap::ReorderEvent));
// We want to make sure that a reorder event comes after any show or
// hide events targeted at the children of its target. We keep the
// invariant that event generation goes up as you are farther in the
// queue, so we want to use the spot of the event with the higher
// generation number, and keep that generation number.
if (reorder &&
reorder->EventGeneration() < event->EventGeneration()) {
reorder->SetEventGeneration(event->EventGeneration());
// It may be true that reorder was before event, and we coalesced
// away all the show / hide events between them. In that case
// event is already immediately after reorder in the queue and we
// do not need to rearrange the list of events.
if (event != reorder->NextEvent()) {
// There really should be a show or hide event before the first
// reorder event.
if (reorder->PrevEvent()) {
reorder->PrevEvent()->SetNextEvent(reorder->NextEvent());
} else {
mFirstMutationEvent = reorder->NextEvent();
}
reorder->NextEvent()->SetPrevEvent(reorder->PrevEvent());
event->PrevEvent()->SetNextEvent(reorder);
reorder->SetPrevEvent(event->PrevEvent());
event->SetPrevEvent(reorder);
reorder->SetNextEvent(event);
}
}
DropMutationEvent(event);
break;
}
acc = parent;
}
} else if (eventType == nsIAccessibleEvent::EVENT_SHOW) {
LocalAccessible* parent = event->GetAccessible()->LocalParent();
while (parent) {
if (parent->IsDoc()) {
break;
}
// if the parent of a show event is being either shown or hidden then
// we don't need to fire a show event for a subtree of that change.
if (parent->ShowEventTarget() || parent->HideEventTarget()) {
DropMutationEvent(event);
break;
}
parent = parent->LocalParent();
}
} else if (eventType == nsIAccessibleEvent::EVENT_HIDE) {
MOZ_ASSERT(eventType == nsIAccessibleEvent::EVENT_HIDE,
"mutation event list has an invalid event");
AccHideEvent* hideEvent = downcast_accEvent(event);
CoalesceHideEvent(hideEvent);
}
event = nextEvent;
}
}
void NotificationController::ScheduleChildDocBinding(DocAccessible* aDocument) {
// Schedule child document binding to the tree.
mHangingChildDocuments.AppendElement(aDocument);
ScheduleProcessing();
}
void NotificationController::ScheduleContentInsertion(
LocalAccessible* aContainer, nsTArray<nsCOMPtr<nsIContent>>& aInsertions) {
if (!aInsertions.IsEmpty()) {
mContentInsertions.GetOrInsertNew(aContainer)->AppendElements(aInsertions);
ScheduleProcessing();
}
}
void NotificationController::ScheduleProcessing() {
// If notification flush isn't planned yet, start notification flush
// asynchronously (after style and layout).
// Note: the mPresShell null-check might be unnecessary; it's just to prevent
// a null-deref here, if we somehow get called after we've been shut down.
if (mObservingState == eNotObservingRefresh && mPresShell) {
if (mPresShell->AddRefreshObserver(this, FlushType::Display,
"Accessibility notifications")) {
mObservingState = eRefreshObserving;
}
}
}
////////////////////////////////////////////////////////////////////////////////
// NotificationCollector: protected
bool NotificationController::IsUpdatePending() {
return mPresShell->ObservingStyleFlushes() ||
mObservingState == eRefreshProcessingForUpdate || WaitingForParent() ||
mContentInsertions.Count() != 0 || mNotifications.Length() != 0 ||
!mTextArray.IsEmpty() ||
!mDocument->HasLoadState(DocAccessible::eTreeConstructed);
}
bool NotificationController::WaitingForParent() {
DocAccessible* parentdoc = mDocument->ParentDocument();
if (!parentdoc) {
return false;
}
NotificationController* parent = parentdoc->mNotificationController;
if (!parent || parent == this) {
// Do not wait for nothing or ourselves
return false;
}
// Wait for parent's notifications processing
return parent->mContentInsertions.Count() != 0 ||
parent->mNotifications.Length() != 0;
}
void NotificationController::ProcessMutationEvents() {
// Firing an event can indirectly run script; e.g. an XPCOM event observer
// or querying a XUL interface. Further mutations might be queued as a result.
// It's important that the mutation queue and state bits from one tick don't
// interfere with the next tick. Otherwise, we can end up dropping events.
// Therefore:
// 1. Clear the state bits, which we only need for coalescence.
for (AccTreeMutationEvent* event = mFirstMutationEvent; event;
event = event->NextEvent()) {
LocalAccessible* acc = event->GetAccessible();
acc->SetShowEventTarget(false);
acc->SetHideEventTarget(false);
acc->SetReorderEventTarget(false);
}
// 2. Keep the current queue locally, but clear the queue on the instance.
RefPtr<AccTreeMutationEvent> firstEvent = mFirstMutationEvent;
mFirstMutationEvent = mLastMutationEvent = nullptr;
mMutationMap.Clear();
mEventGeneration = 0;
// Group the show events by the parent of their target.
nsTHashMap<nsPtrHashKey<LocalAccessible>, nsTArray<AccTreeMutationEvent*>>
showEvents;
for (AccTreeMutationEvent* event = firstEvent; event;
event = event->NextEvent()) {
if (event->GetEventType() != nsIAccessibleEvent::EVENT_SHOW) {
continue;
}
LocalAccessible* parent = event->GetAccessible()->LocalParent();
showEvents.LookupOrInsert(parent).AppendElement(event);
}
// We need to fire show events for the children of an accessible in the order
// of their indices at this point. So sort each set of events for the same
// container by the index of their target. We do this before firing any events
// because firing an event might indirectly run script which might alter the
// tree, breaking our sort. However, we don't actually fire the events yet.
for (auto iter = showEvents.Iter(); !iter.Done(); iter.Next()) {
struct AccIdxComparator {
bool LessThan(const AccTreeMutationEvent* a,
const AccTreeMutationEvent* b) const {
int32_t aIdx = a->GetAccessible()->IndexInParent();
int32_t bIdx = b->GetAccessible()->IndexInParent();
MOZ_ASSERT(aIdx >= 0 && bIdx >= 0 && (a == b || aIdx != bIdx));
return aIdx < bIdx;
}
bool Equals(const AccTreeMutationEvent* a,
const AccTreeMutationEvent* b) const {
DebugOnly<int32_t> aIdx = a->GetAccessible()->IndexInParent();
DebugOnly<int32_t> bIdx = b->GetAccessible()->IndexInParent();
MOZ_ASSERT(aIdx >= 0 && bIdx >= 0 && (a == b || aIdx != bIdx));
return a == b;
}
};
nsTArray<AccTreeMutationEvent*>& events = iter.Data();
events.Sort(AccIdxComparator());
}
// there is no reason to fire a hide event for a child of a show event
// target. That can happen if something is inserted into the tree and
// removed before the next refresh driver tick, but it should not be
// observable outside gecko so it should be safe to coalesce away any such
// events. This means that it should be fine to fire all of the hide events
// first, and then deal with any shown subtrees.
for (AccTreeMutationEvent* event = firstEvent; event;
event = event->NextEvent()) {
if (event->GetEventType() != nsIAccessibleEvent::EVENT_HIDE) {
continue;
}
nsEventShell::FireEvent(event);
if (!mDocument) {
return;
}
AccMutationEvent* mutEvent = downcast_accEvent(event);
if (mutEvent->mTextChangeEvent) {
nsEventShell::FireEvent(mutEvent->mTextChangeEvent);
if (!mDocument) {
return;
}
}
// Fire menupopup end event before a hide event if a menu goes away.
// XXX: We don't look into children of hidden subtree to find hiding
// menupopup (as we did prior bug 570275) because we don't do that when
// menu is showing (and that's impossible until bug 606924 is fixed).
// Nevertheless we should do this at least because layout coalesces
// the changes before our processing and we may miss some menupopup
// events. Now we just want to be consistent in content insertion/removal
// handling.
if (event->mAccessible->ARIARole() == roles::MENUPOPUP) {
nsEventShell::FireEvent(nsIAccessibleEvent::EVENT_MENUPOPUP_END,
event->mAccessible);
if (!mDocument) {
return;
}
}
AccHideEvent* hideEvent = downcast_accEvent(event);
if (hideEvent->NeedsShutdown()) {
mDocument->ShutdownChildrenInSubtree(event->mAccessible);
}
}
// Fire the show events we sorted earlier.
for (auto iter = showEvents.Iter(); !iter.Done(); iter.Next()) {
nsTArray<AccTreeMutationEvent*>& events = iter.Data();
for (AccTreeMutationEvent* event : events) {
nsEventShell::FireEvent(event);
if (!mDocument) {
return;
}
AccMutationEvent* mutEvent = downcast_accEvent(event);
if (mutEvent->mTextChangeEvent) {
nsEventShell::FireEvent(mutEvent->mTextChangeEvent);
if (!mDocument) {
return;
}
}
}
}
// Now we can fire the reorder events after all the show and hide events.
for (const uint32_t reorderType : {nsIAccessibleEvent::EVENT_INNER_REORDER,
nsIAccessibleEvent::EVENT_REORDER}) {
for (AccTreeMutationEvent* event = firstEvent; event;
event = event->NextEvent()) {
if (event->GetEventType() != reorderType) {
continue;
}
if (event->GetAccessible()->IsDefunct()) {
// An inner reorder target may have been hidden itself and no
// longer bound to the document.
MOZ_ASSERT(reorderType == nsIAccessibleEvent::EVENT_INNER_REORDER,
"An 'outer' reorder target should not be defunct");
continue;
}
nsEventShell::FireEvent(event);
if (!mDocument) {
return;
}
LocalAccessible* target = event->GetAccessible();
target->Document()->MaybeNotifyOfValueChange(target);
if (!mDocument) {
return;
}
}
}
// Our events are in a doubly linked list. Clear the pointers to reduce
// pressure on the cycle collector. Even though clearing the previous pointers
// removes cycles, this isn't enough. The cycle collector still gets bogged
// down when there are lots of mutation events if the next pointers aren't
// cleared. Even without the cycle collector, not clearing the next pointers
// potentially results in deep recursion because releasing each event releases
// its next event.
RefPtr<AccTreeMutationEvent> event = firstEvent;
while (event) {
RefPtr<AccTreeMutationEvent> next = event->NextEvent();
event->SetNextEvent(nullptr);
event->SetPrevEvent(nullptr);
event = next;
}
}
////////////////////////////////////////////////////////////////////////////////
// NotificationCollector: private
void NotificationController::WillRefresh(mozilla::TimeStamp aTime) {
AUTO_PROFILER_MARKER_TEXT("NotificationController::WillRefresh", A11Y, {},
""_ns);
Telemetry::AutoTimer<Telemetry::A11Y_TREE_UPDATE_TIMING_MS> timer;
// DO NOT ADD CODE ABOVE THIS BLOCK: THIS CODE IS MEASURING TIMINGS.
AUTO_PROFILER_LABEL("NotificationController::WillRefresh", A11Y);
// If mDocument is null, the document accessible that this notification
// controller was created for is now shut down. This means we've lost our
// ability to unregister ourselves, which is bad. (However, it also shouldn't
// be logically possible for us to get here with a null mDocument; the only
// thing that clears that pointer is our Shutdown() method, which first
// unregisters and fatally asserts if that fails).
MOZ_RELEASE_ASSERT(
mDocument,
"The document was shut down while refresh observer is attached!");
if (ipc::ProcessChild::ExpectingShutdown()) {
return;
}
// Wait until an update, we have started, or an interruptible reflow is
// finished. We also check the existance of our pres context and root pres
// context, since if we can't reach either of these the frame tree is being
// destroyed.
nsPresContext* pc = mPresShell->GetPresContext();
if (mObservingState == eRefreshProcessing ||
mObservingState == eRefreshProcessingForUpdate ||
mPresShell->IsReflowInterrupted() || !pc || !pc->GetRootPresContext()) {
return;
}
// Process parent's notifications before ours, to get proper ordering between
// e.g. tab event and content event.
if (WaitingForParent()) {
mDocument->ParentDocument()->mNotificationController->WillRefresh(aTime);
if (!mDocument || ipc::ProcessChild::ExpectingShutdown()) {
return;
}
}
// Any generic notifications should be queued if we're processing content
// insertions or generic notifications.
mObservingState = eRefreshProcessingForUpdate;
// Initial accessible tree construction.
if (!mDocument->HasLoadState(DocAccessible::eTreeConstructed)) {
// (1) If document is not bound to parent at this point, or
// (2) the PresShell is not initialized (and it isn't about:blank),
// then the document is not ready yet (process notifications later).
if (!mDocument->IsBoundToParent() ||
(!mPresShell->DidInitialize() &&
!mDocument->DocumentNode()->IsInitialDocument())) {
mObservingState = eRefreshObserving;
return;
}
#ifdef A11Y_LOG
if (logging::IsEnabled(logging::eTree)) {
logging::MsgBegin("TREE", "initial tree created");
logging::Address("document", mDocument);
logging::MsgEnd();
}
#endif
mDocument->DoInitialUpdate();
if (ipc::ProcessChild::ExpectingShutdown()) {
return;
}
NS_ASSERTION(mContentInsertions.Count() == 0,
"Pending content insertions while initial accessible tree "
"isn't created!");
}
mDocument->ProcessPendingUpdates();
// Process rendered text change notifications. Even though we want to process
// them in the order in which they were queued, we still want to avoid
// duplicates.
nsTHashSet<nsIContent*> textHash;
for (nsIContent* textNode : mTextArray) {
if (!textHash.EnsureInserted(textNode)) {
continue; // Already processed.
}
LocalAccessible* textAcc = mDocument->GetAccessible(textNode);
// If the text node is not in tree or doesn't have a frame, or placed in
// another document, then this case should have been handled already by
// content removal notifications.
nsINode* containerNode = textNode->GetFlattenedTreeParentNode();
if (!containerNode || textNode->OwnerDoc() != mDocument->DocumentNode()) {
MOZ_ASSERT(!textAcc,
"Text node was removed but accessible is kept alive!");
continue;
}
nsIFrame* textFrame = textNode->GetPrimaryFrame();
if (!textFrame) {
MOZ_ASSERT(!textAcc,
"Text node isn't rendered but accessible is kept alive!");
continue;
}
#ifdef A11Y_LOG
nsIContent* containerElm =
containerNode->IsElement() ? containerNode->AsElement() : nullptr;
#endif
nsIFrame::RenderedText text = textFrame->GetRenderedText(
0, UINT32_MAX, nsIFrame::TextOffsetType::OffsetsInContentText,
nsIFrame::TrailingWhitespace::DontTrim);
// Remove text accessible if rendered text is empty.
if (textAcc) {
if (text.mString.IsEmpty()) {
#ifdef A11Y_LOG
if (logging::IsEnabled(logging::eTree | logging::eText)) {
logging::MsgBegin("TREE", "text node lost its content; doc: %p",
mDocument);
logging::Node("container", containerElm);
logging::Node("content", textNode);
logging::MsgEnd();
}
#endif
mDocument->ContentRemoved(textAcc);
continue;
}
// Update text of the accessible and fire text change events.
#ifdef A11Y_LOG
if (logging::IsEnabled(logging::eText)) {
logging::MsgBegin("TEXT", "text may be changed; doc: %p", mDocument);
logging::Node("container", containerElm);
logging::Node("content", textNode);
logging::MsgEntry(
"old text '%s'",
NS_ConvertUTF16toUTF8(textAcc->AsTextLeaf()->Text()).get());
logging::MsgEntry("new text: '%s'",
NS_ConvertUTF16toUTF8(text.mString).get());
logging::MsgEnd();
}
#endif
if (CssAltContent(textNode)) {
// A11y doesn't care about the text rendered by layout if there is CSS
// content alt text. We skip this here rather than when the update is
// queued because the TextLeafAccessible might not exist yet and we
// might need to create it below.
continue;
}
TextUpdater::Run(mDocument, textAcc->AsTextLeaf(), text.mString);
continue;
}
// Append an accessible if rendered text is not empty.
if (!text.mString.IsEmpty()) {
#ifdef A11Y_LOG
if (logging::IsEnabled(logging::eTree | logging::eText)) {
logging::MsgBegin("TREE", "text node gains new content; doc: %p",
mDocument);
logging::Node("container", containerElm);
logging::Node("content", textNode);
logging::MsgEnd();
}
#endif
MOZ_ASSERT(mDocument->AccessibleOrTrueContainer(containerNode),
"Text node having rendered text hasn't accessible document!");
LocalAccessible* container =
mDocument->AccessibleOrTrueContainer(containerNode, true);
if (container) {
nsTArray<nsCOMPtr<nsIContent>>* list =
mContentInsertions.GetOrInsertNew(container);
list->AppendElement(textNode);
}
}
}
textHash.Clear();
mTextArray.Clear();
// Process content inserted notifications to update the tree.
// Processing an insertion can indirectly run script (e.g. querying a XUL
// interface), which might result in another insertion being queued.
// We don't want to lose any queued insertions if this happens. Therefore, we
// move the current insertions into a temporary data structure and process
// them from there. Any insertions queued during processing will get handled
// in subsequent refresh driver ticks.
const auto contentInsertions = std::move(mContentInsertions);
for (const auto& entry : contentInsertions) {
mDocument->ProcessContentInserted(entry.GetKey(), entry.GetData().get());
if (!mDocument) {
return;
}
}
// Bind hanging child documents unless we are using IPC and the
// document has no IPC actor. If we fail to bind the child doc then
// shut it down.
uint32_t hangingDocCnt = mHangingChildDocuments.Length();
nsTArray<RefPtr<DocAccessible>> newChildDocs;
for (uint32_t idx = 0; idx < hangingDocCnt; idx++) {
DocAccessible* childDoc = mHangingChildDocuments[idx];
if (childDoc->IsDefunct()) {
continue;
}
if (IPCAccessibilityActive() && !mDocument->IPCDoc()) {
childDoc->Shutdown();
continue;
}
nsIContent* ownerContent = childDoc->DocumentNode()->GetEmbedderElement();
if (ownerContent) {
LocalAccessible* outerDocAcc = mDocument->GetAccessible(ownerContent);
if (outerDocAcc && outerDocAcc->AppendChild(childDoc)) {
if (mDocument->AppendChildDocument(childDoc)) {
newChildDocs.AppendElement(std::move(mHangingChildDocuments[idx]));
continue;
}
outerDocAcc->RemoveChild(childDoc);
}
// Failed to bind the child document, destroy it.
childDoc->Shutdown();
}
}
// Clear the hanging documents list, even if we didn't bind them.
mHangingChildDocuments.Clear();
MOZ_ASSERT(mDocument, "Illicit document shutdown");
if (!mDocument) {
return;
}
// If the document is ready and all its subdocuments are completely loaded
// then process the document load.
if (mDocument->HasLoadState(DocAccessible::eReady) &&
!mDocument->HasLoadState(DocAccessible::eCompletelyLoaded) &&
hangingDocCnt == 0) {
uint32_t childDocCnt = mDocument->ChildDocumentCount(), childDocIdx = 0;
for (; childDocIdx < childDocCnt; childDocIdx++) {
DocAccessible* childDoc = mDocument->GetChildDocumentAt(childDocIdx);
if (!childDoc->HasLoadState(DocAccessible::eCompletelyLoaded)) {
break;
}
}
if (childDocIdx == childDocCnt) {
mDocument->ProcessLoad();
if (!mDocument) {
return;
}
}
}
// Process invalidation list of the document after all accessible tree
// mutation is done.
mDocument->ProcessInvalidationList();
// Process relocation list.
for (uint32_t idx = 0; idx < mRelocations.Length(); idx++) {
// owner should be in a document and have na associated DOM node (docs
// sometimes don't)
if (mRelocations[idx]->IsInDocument() &&
mRelocations[idx]->HasOwnContent()) {
mDocument->DoARIAOwnsRelocation(mRelocations[idx]);
}
}
mRelocations.Clear();
// Process only currently queued generic notifications.
// These are used for processing aria-activedescendant, DOMMenuItemActive,
// etc. Therefore, they must be processed after relocations, since relocated
// subtrees might not have been created before relocation processing and the
// target might be inside a relocated subtree.
const nsTArray<RefPtr<Notification>> notifications =
std::move(mNotifications);
uint32_t notificationCount = notifications.Length();
for (uint32_t idx = 0; idx < notificationCount; idx++) {
notifications[idx]->Process();
if (!mDocument) {
return;
}
}
if (ipc::ProcessChild::ExpectingShutdown()) {
return;
}
// If a generic notification occurs after this point then we may be allowed to
// process it synchronously. However we do not want to reenter if fireing
// events causes script to run.
mObservingState = eRefreshProcessing;
mDocument->SendAccessiblesWillMove();
// Send any queued cache updates before we fire any mutation events so the
// cache is up to date when mutation events are fired. We do this after
// insertions (but not their events) so that cache updates dependent on the
// tree work correctly; e.g. line start calculation.
if (IPCAccessibilityActive() && mDocument) {
mDocument->ProcessQueuedCacheUpdates();
}
CoalesceMutationEvents();
ProcessMutationEvents();
// When firing mutation events, mObservingState is set to
// eRefreshProcessing. Any calls to ScheduleProcessing() that
// occur before mObservingState is reset will be dropped because we only
// schedule a tick if mObservingState == eNotObservingRefresh.
// This sometimes results in our viewport cache being out-of-date after
// processing mutation events. Call ProcessQueuedCacheUpdates again to
// ensure it is updated.
if (IPCAccessibilityActive() && mDocument) {
mDocument->ProcessQueuedCacheUpdates();
}
if (mDocument) {
mDocument->ClearMutationData();
}
if (ipc::ProcessChild::ExpectingShutdown()) {
return;
}
ProcessEventQueue();
if (IPCAccessibilityActive()) {
size_t newDocCount = newChildDocs.Length();
for (size_t i = 0; i < newDocCount; i++) {
DocAccessible* childDoc = newChildDocs[i];
if (childDoc->IsDefunct()) {
continue;
}
LocalAccessible* parent = childDoc->LocalParent();
DocAccessibleChild* parentIPCDoc = mDocument->IPCDoc();
MOZ_DIAGNOSTIC_ASSERT(parentIPCDoc);
uint64_t id = reinterpret_cast<uintptr_t>(parent->UniqueID());
MOZ_DIAGNOSTIC_ASSERT(id);
DocAccessibleChild* ipcDoc = childDoc->IPCDoc();
if (ipcDoc) {
parentIPCDoc->SendBindChildDoc(WrapNotNull(ipcDoc), id);
continue;
}
ipcDoc = new DocAccessibleChild(childDoc, parentIPCDoc->Manager());
childDoc->SetIPCDoc(ipcDoc);
nsCOMPtr<nsIBrowserChild> browserChild =
do_GetInterface(mDocument->DocumentNode()->GetDocShell());
if (browserChild) {
static_cast<BrowserChild*>(browserChild.get())
->SendPDocAccessibleConstructor(
ipcDoc, parentIPCDoc, id,
childDoc->DocumentNode()->GetBrowsingContext());
}
}
}
if (!mDocument) {
// A null mDocument means we've gotten a Shutdown() call (presumably via
// some script that we triggered above), and that means we're done here.
// Note: in this case, it's important that don't modify mObservingState;
// Shutdown() will have *unregistered* us as a refresh observer, and we
// don't want to mistakenly overwrite mObservingState and fool ourselves
// into thinking we've re-registered when we really haven't!
MOZ_ASSERT(mObservingState == eNotObservingRefresh,
"We've been shutdown, which means we should've been "
"unregistered as a refresh observer");
return;
}
mObservingState = eRefreshObserving;
// Stop further processing if there are no new notifications of any kind or
// events and document load is processed.
if (mContentInsertions.Count() == 0 && mNotifications.IsEmpty() &&
!mFocusEvent && mEvents.IsEmpty() && mTextArray.IsEmpty() &&
mHangingChildDocuments.IsEmpty() &&
mDocument->HasLoadState(DocAccessible::eCompletelyLoaded) &&
mPresShell->RemoveRefreshObserver(this, FlushType::Display)) {
mObservingState = eNotObservingRefresh;
}
}
void NotificationController::EventMap::PutEvent(AccTreeMutationEvent* aEvent) {
EventType type = GetEventType(aEvent);
uint64_t addr = reinterpret_cast<uintptr_t>(aEvent->GetAccessible());
MOZ_ASSERT((addr & 0x3) == 0, "accessible is not 4 byte aligned");
addr |= type;
mTable.InsertOrUpdate(addr, RefPtr{aEvent});
}
AccTreeMutationEvent* NotificationController::EventMap::GetEvent(
LocalAccessible* aTarget, EventType aType) {
uint64_t addr = reinterpret_cast<uintptr_t>(aTarget);
MOZ_ASSERT((addr & 0x3) == 0, "target is not 4 byte aligned");
addr |= aType;
return mTable.GetWeak(addr);
}
void NotificationController::EventMap::RemoveEvent(
AccTreeMutationEvent* aEvent) {
EventType type = GetEventType(aEvent);
uint64_t addr = reinterpret_cast<uintptr_t>(aEvent->GetAccessible());
MOZ_ASSERT((addr & 0x3) == 0, "accessible is not 4 byte aligned");
addr |= type;
MOZ_ASSERT(mTable.GetWeak(addr) == aEvent, "mTable has the wrong event");
mTable.Remove(addr);
}
NotificationController::EventMap::EventType
NotificationController::EventMap::GetEventType(AccTreeMutationEvent* aEvent) {
switch (aEvent->GetEventType()) {
case nsIAccessibleEvent::EVENT_SHOW:
return ShowEvent;
case nsIAccessibleEvent::EVENT_HIDE:
return HideEvent;
case nsIAccessibleEvent::EVENT_REORDER:
case nsIAccessibleEvent::EVENT_INNER_REORDER:
return ReorderEvent;
default:
MOZ_ASSERT_UNREACHABLE("event has invalid type");
return ShowEvent;
}
}