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/* -*- 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
#include "EventQueue.h"
#include "LocalAccessible-inl.h"
#include "nsEventShell.h"
#include "DocAccessibleChild.h"
#include "nsTextEquivUtils.h"
#ifdef A11Y_LOG
# include "Logging.h"
#endif
#include "Relation.h"
namespace mozilla {
namespace a11y {
// Defines the number of selection add/remove events in the queue when they
// aren't packed into single selection within event.
const unsigned int kSelChangeCountToPack = 5;
////////////////////////////////////////////////////////////////////////////////
// EventQueue
////////////////////////////////////////////////////////////////////////////////
bool EventQueue::PushEvent(AccEvent* aEvent) {
NS_ASSERTION((aEvent->mAccessible && aEvent->mAccessible->IsApplication()) ||
aEvent->Document() == mDocument,
"Queued event belongs to another document!");
if (aEvent->mEventType == nsIAccessibleEvent::EVENT_FOCUS) {
mFocusEvent = aEvent;
return true;
}
// pretended earlier, or change the return type to void.
mEvents.AppendElement(aEvent);
// Filter events.
CoalesceEvents();
if (aEvent->mEventRule != AccEvent::eDoNotEmit &&
(aEvent->mEventType == nsIAccessibleEvent::EVENT_NAME_CHANGE ||
aEvent->mEventType == nsIAccessibleEvent::EVENT_TEXT_REMOVED ||
aEvent->mEventType == nsIAccessibleEvent::EVENT_TEXT_INSERTED)) {
PushNameOrDescriptionChange(aEvent);
}
return true;
}
bool EventQueue::PushNameOrDescriptionChange(AccEvent* aOrigEvent) {
// Fire name/description change event on parent or related LocalAccessible
// being labelled/described given that this event hasn't been coalesced, the
// dependent's name/description was calculated from this subtree, and the
// subtree was changed.
LocalAccessible* target = aOrigEvent->mAccessible;
// If the text of a text leaf changed without replacing the leaf, the only
// event we get is text inserted on the container. In this case, we might
// need to fire a name change event on the target itself.
const bool maybeTargetNameChanged =
(aOrigEvent->mEventType == nsIAccessibleEvent::EVENT_TEXT_REMOVED ||
aOrigEvent->mEventType == nsIAccessibleEvent::EVENT_TEXT_INSERTED) &&
nsTextEquivUtils::HasNameRule(target, eNameFromSubtreeRule);
const bool doName = target->HasNameDependent() || maybeTargetNameChanged;
const bool doDesc = target->HasDescriptionDependent();
if (!doName && !doDesc) {
return false;
}
bool pushed = false;
bool nameCheckAncestor = true;
// Only continue traversing up the tree if it's possible that the parent
// LocalAccessible's name (or a LocalAccessible being labelled by this
// LocalAccessible or an ancestor) can depend on this LocalAccessible's name.
LocalAccessible* parent = target;
do {
// Test possible name dependent parent.
if (doName) {
if (nameCheckAncestor && (maybeTargetNameChanged || parent != target) &&
nsTextEquivUtils::HasNameRule(parent, eNameFromSubtreeRule)) {
nsAutoString name;
ENameValueFlag nameFlag = parent->Name(name);
// If name is obtained from subtree, fire name change event.
// HTML file inputs always get part of their name from the subtree, even
// if the author provided a name.
if (nameFlag == eNameFromSubtree || parent->IsHTMLFileInput()) {
RefPtr<AccEvent> nameChangeEvent =
new AccEvent(nsIAccessibleEvent::EVENT_NAME_CHANGE, parent);
pushed |= PushEvent(nameChangeEvent);
}
nameCheckAncestor = false;
}
Relation rel = parent->RelationByType(RelationType::LABEL_FOR);
while (LocalAccessible* relTarget = rel.LocalNext()) {
RefPtr<AccEvent> nameChangeEvent =
new AccEvent(nsIAccessibleEvent::EVENT_NAME_CHANGE, relTarget);
pushed |= PushEvent(nameChangeEvent);
}
}
if (doDesc) {
Relation rel = parent->RelationByType(RelationType::DESCRIPTION_FOR);
while (LocalAccessible* relTarget = rel.LocalNext()) {
RefPtr<AccEvent> descChangeEvent = new AccEvent(
nsIAccessibleEvent::EVENT_DESCRIPTION_CHANGE, relTarget);
pushed |= PushEvent(descChangeEvent);
}
}
if (parent->IsDoc()) {
// Never cross document boundaries.
break;
}
parent = parent->LocalParent();
} while (parent &&
nsTextEquivUtils::HasNameRule(parent, eNameFromSubtreeIfReqRule));
return pushed;
}
////////////////////////////////////////////////////////////////////////////////
// EventQueue: private
void EventQueue::CoalesceEvents() {
NS_ASSERTION(mEvents.Length(), "There should be at least one pending event!");
uint32_t tail = mEvents.Length() - 1;
AccEvent* tailEvent = mEvents[tail];
switch (tailEvent->mEventRule) {
case AccEvent::eCoalesceReorder: {
DebugOnly<LocalAccessible*> target = tailEvent->mAccessible.get();
MOZ_ASSERT(
target->IsApplication() || target->IsOuterDoc() ||
target->IsXULTree(),
"Only app or outerdoc accessible reorder events are in the queue");
MOZ_ASSERT(tailEvent->GetEventType() == nsIAccessibleEvent::EVENT_REORDER,
"only reorder events should be queued");
break; // case eCoalesceReorder
}
case AccEvent::eCoalesceOfSameType: {
// Coalesce old events by newer event.
for (uint32_t index = tail - 1; index < tail; index--) {
AccEvent* accEvent = mEvents[index];
if (accEvent->mEventType == tailEvent->mEventType &&
accEvent->mEventRule == tailEvent->mEventRule) {
accEvent->mEventRule = AccEvent::eDoNotEmit;
return;
}
}
break; // case eCoalesceOfSameType
}
case AccEvent::eCoalesceSelectionChange: {
AccSelChangeEvent* tailSelChangeEvent = downcast_accEvent(tailEvent);
for (uint32_t index = tail - 1; index < tail; index--) {
AccEvent* thisEvent = mEvents[index];
if (thisEvent->mEventRule == tailEvent->mEventRule) {
AccSelChangeEvent* thisSelChangeEvent = downcast_accEvent(thisEvent);
// Coalesce selection change events within same control.
if (tailSelChangeEvent->mWidget == thisSelChangeEvent->mWidget) {
CoalesceSelChangeEvents(tailSelChangeEvent, thisSelChangeEvent,
index);
return;
}
}
}
break; // eCoalesceSelectionChange
}
case AccEvent::eCoalesceStateChange: {
// If state change event is duped then ignore previous event. If state
// change event is opposite to previous event then no event is emitted
// (accessible state wasn't changed).
for (uint32_t index = tail - 1; index < tail; index--) {
AccEvent* thisEvent = mEvents[index];
if (thisEvent->mEventRule != AccEvent::eDoNotEmit &&
thisEvent->mEventType == tailEvent->mEventType &&
thisEvent->mAccessible == tailEvent->mAccessible) {
AccStateChangeEvent* thisSCEvent = downcast_accEvent(thisEvent);
AccStateChangeEvent* tailSCEvent = downcast_accEvent(tailEvent);
if (thisSCEvent->mState == tailSCEvent->mState) {
thisEvent->mEventRule = AccEvent::eDoNotEmit;
if (thisSCEvent->mIsEnabled != tailSCEvent->mIsEnabled) {
tailEvent->mEventRule = AccEvent::eDoNotEmit;
}
}
}
}
break; // eCoalesceStateChange
}
case AccEvent::eCoalesceTextSelChange: {
// Coalesce older event by newer event for the same selection or target.
// Events for same selection may have different targets and vice versa one
// target may be pointed by different selections (for latter see
for (uint32_t index = tail - 1; index < tail; index--) {
AccEvent* thisEvent = mEvents[index];
if (thisEvent->mEventRule != AccEvent::eDoNotEmit &&
thisEvent->mEventType == tailEvent->mEventType) {
AccTextSelChangeEvent* thisTSCEvent = downcast_accEvent(thisEvent);
AccTextSelChangeEvent* tailTSCEvent = downcast_accEvent(tailEvent);
if (thisTSCEvent->mSel == tailTSCEvent->mSel ||
thisEvent->mAccessible == tailEvent->mAccessible) {
thisEvent->mEventRule = AccEvent::eDoNotEmit;
}
}
}
break; // eCoalesceTextSelChange
}
case AccEvent::eRemoveDupes: {
// Check for repeat events, coalesce newly appended event by more older
// event.
for (uint32_t index = tail - 1; index < tail; index--) {
AccEvent* accEvent = mEvents[index];
if (accEvent->mEventType == tailEvent->mEventType &&
accEvent->mEventRule == tailEvent->mEventRule &&
accEvent->mAccessible == tailEvent->mAccessible) {
tailEvent->mEventRule = AccEvent::eDoNotEmit;
return;
}
}
break; // case eRemoveDupes
}
default:
break; // case eAllowDupes, eDoNotEmit
} // switch
}
void EventQueue::CoalesceSelChangeEvents(AccSelChangeEvent* aTailEvent,
AccSelChangeEvent* aThisEvent,
uint32_t aThisIndex) {
aTailEvent->mPreceedingCount = aThisEvent->mPreceedingCount + 1;
// Pack all preceding events into single selection within event
// when we receive too much selection add/remove events.
if (aTailEvent->mPreceedingCount >= kSelChangeCountToPack) {
aTailEvent->mEventType = nsIAccessibleEvent::EVENT_SELECTION_WITHIN;
aTailEvent->mAccessible = aTailEvent->mWidget;
aThisEvent->mEventRule = AccEvent::eDoNotEmit;
// Do not emit any preceding selection events for same widget if they
// weren't coalesced yet.
if (aThisEvent->mEventType != nsIAccessibleEvent::EVENT_SELECTION_WITHIN) {
for (uint32_t jdx = aThisIndex - 1; jdx < aThisIndex; jdx--) {
AccEvent* prevEvent = mEvents[jdx];
if (prevEvent->mEventRule == aTailEvent->mEventRule) {
AccSelChangeEvent* prevSelChangeEvent = downcast_accEvent(prevEvent);
if (prevSelChangeEvent->mWidget == aTailEvent->mWidget) {
prevSelChangeEvent->mEventRule = AccEvent::eDoNotEmit;
}
}
}
}
return;
}
// Pack sequential selection remove and selection add events into
// single selection change event.
if (aTailEvent->mPreceedingCount == 1 &&
aTailEvent->mItem != aThisEvent->mItem) {
if (aTailEvent->mSelChangeType == AccSelChangeEvent::eSelectionAdd &&
aThisEvent->mSelChangeType == AccSelChangeEvent::eSelectionRemove) {
aThisEvent->mEventRule = AccEvent::eDoNotEmit;
aTailEvent->mEventType = nsIAccessibleEvent::EVENT_SELECTION;
aTailEvent->mPackedEvent = aThisEvent;
return;
}
if (aThisEvent->mSelChangeType == AccSelChangeEvent::eSelectionAdd &&
aTailEvent->mSelChangeType == AccSelChangeEvent::eSelectionRemove) {
aTailEvent->mEventRule = AccEvent::eDoNotEmit;
aThisEvent->mEventType = nsIAccessibleEvent::EVENT_SELECTION;
aThisEvent->mPackedEvent = aTailEvent;
return;
}
}
// Unpack the packed selection change event because we've got one
// more selection add/remove.
if (aThisEvent->mEventType == nsIAccessibleEvent::EVENT_SELECTION) {
if (aThisEvent->mPackedEvent) {
aThisEvent->mPackedEvent->mEventType =
aThisEvent->mPackedEvent->mSelChangeType ==
AccSelChangeEvent::eSelectionAdd
? nsIAccessibleEvent::EVENT_SELECTION_ADD
: nsIAccessibleEvent::EVENT_SELECTION_REMOVE;
aThisEvent->mPackedEvent->mEventRule = AccEvent::eCoalesceSelectionChange;
aThisEvent->mPackedEvent = nullptr;
}
aThisEvent->mEventType =
aThisEvent->mSelChangeType == AccSelChangeEvent::eSelectionAdd
? nsIAccessibleEvent::EVENT_SELECTION_ADD
: nsIAccessibleEvent::EVENT_SELECTION_REMOVE;
return;
}
// Convert into selection add since control has single selection but other
// selection events for this control are queued.
if (aTailEvent->mEventType == nsIAccessibleEvent::EVENT_SELECTION) {
aTailEvent->mEventType = nsIAccessibleEvent::EVENT_SELECTION_ADD;
}
}
////////////////////////////////////////////////////////////////////////////////
// EventQueue: event queue
void EventQueue::ProcessEventQueue() {
// Process only currently queued events.
const nsTArray<RefPtr<AccEvent> > events = std::move(mEvents);
nsTArray<uint64_t> selectedIDs;
nsTArray<uint64_t> unselectedIDs;
uint32_t eventCount = events.Length();
#ifdef A11Y_LOG
if ((eventCount > 0 || mFocusEvent) && logging::IsEnabled(logging::eEvents)) {
logging::MsgBegin("EVENTS", "events processing");
logging::Address("document", mDocument);
logging::MsgEnd();
}
#endif
if (mFocusEvent) {
// Always fire a pending focus event before all other events. We do this for
// two reasons:
// 1. It prevents extraneous screen reader speech if the name, states, etc.
// of the currently focused item change at the same time as another item is
// focused. If aria-activedescendant is used, even setting
// aria-activedescendant before changing other properties results in the
// property change events being queued before the focus event because we
// process aria-activedescendant async.
// 2. It improves perceived performance. Focus changes should be reported as
// soon as possible, so clients should handle focus events before they spend
// time on anything else.
RefPtr<AccEvent> event = std::move(mFocusEvent);
if (!event->mAccessible->IsDefunct()) {
FocusMgr()->ProcessFocusEvent(event);
}
}
for (uint32_t idx = 0; idx < eventCount; idx++) {
AccEvent* event = events[idx];
uint32_t eventType = event->mEventType;
LocalAccessible* target = event->GetAccessible();
if (!target || target->IsDefunct()) {
continue;
}
// Collect select changes
if (IPCAccessibilityActive()) {
if ((event->mEventRule == AccEvent::eDoNotEmit &&
(eventType == nsIAccessibleEvent::EVENT_SELECTION_ADD ||
eventType == nsIAccessibleEvent::EVENT_SELECTION_REMOVE ||
eventType == nsIAccessibleEvent::EVENT_SELECTION)) ||
eventType == nsIAccessibleEvent::EVENT_SELECTION_WITHIN) {
// The selection even was either dropped or morphed to a
// selection-within. We need to collect the items from all these events
// and manually push their new state to the parent process.
AccSelChangeEvent* selChangeEvent = downcast_accEvent(event);
LocalAccessible* item = selChangeEvent->mItem;
if (!item->IsDefunct()) {
uint64_t itemID =
item->IsDoc() ? 0 : reinterpret_cast<uint64_t>(item->UniqueID());
bool selected = selChangeEvent->mSelChangeType ==
AccSelChangeEvent::eSelectionAdd;
if (selected) {
selectedIDs.AppendElement(itemID);
} else {
unselectedIDs.AppendElement(itemID);
}
}
}
}
if (event->mEventRule == AccEvent::eDoNotEmit) {
continue;
}
// Dispatch caret moved and text selection change events.
if (eventType == nsIAccessibleEvent::EVENT_TEXT_SELECTION_CHANGED) {
SelectionMgr()->ProcessTextSelChangeEvent(event);
continue;
}
// Fire selected state change events in support to selection events.
if (eventType == nsIAccessibleEvent::EVENT_SELECTION_ADD) {
nsEventShell::FireEvent(event->mAccessible, states::SELECTED, true,
event->mIsFromUserInput);
} else if (eventType == nsIAccessibleEvent::EVENT_SELECTION_REMOVE) {
nsEventShell::FireEvent(event->mAccessible, states::SELECTED, false,
event->mIsFromUserInput);
} else if (eventType == nsIAccessibleEvent::EVENT_SELECTION) {
AccSelChangeEvent* selChangeEvent = downcast_accEvent(event);
nsEventShell::FireEvent(
event->mAccessible, states::SELECTED,
(selChangeEvent->mSelChangeType == AccSelChangeEvent::eSelectionAdd),
event->mIsFromUserInput);
if (selChangeEvent->mPackedEvent) {
nsEventShell::FireEvent(selChangeEvent->mPackedEvent->mAccessible,
states::SELECTED,
(selChangeEvent->mPackedEvent->mSelChangeType ==
AccSelChangeEvent::eSelectionAdd),
selChangeEvent->mPackedEvent->mIsFromUserInput);
}
}
nsEventShell::FireEvent(event);
if (!mDocument) {
return;
}
}
if (mDocument && IPCAccessibilityActive() &&
(!selectedIDs.IsEmpty() || !unselectedIDs.IsEmpty())) {
DocAccessibleChild* ipcDoc = mDocument->IPCDoc();
ipcDoc->SendSelectedAccessiblesChanged(selectedIDs, unselectedIDs);
}
}
} // namespace a11y
} // namespace mozilla