gecko-dev/accessible/base/EventQueue.cpp

560 строки
20 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 "EventQueue.h"
#include "Accessible-inl.h"
#include "nsEventShell.h"
#include "DocAccessible.h"
#include "nsAccessibilityService.h"
#include "nsTextEquivUtils.h"
#ifdef A11Y_LOG
#include "Logging.h"
#endif
using namespace mozilla;
using namespace mozilla::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->GetDocAccessible() == mDocument,
"Queued event belongs to another document!");
if (!mEvents.AppendElement(aEvent))
return false;
// Filter events.
CoalesceEvents();
// Fire name change event on parent given that this event hasn't been
// coalesced, the parent's name was calculated from its subtree, and the
// subtree was changed.
Accessible* target = aEvent->mAccessible;
if (aEvent->mEventRule != AccEvent::eDoNotEmit &&
target->HasNameDependentParent() &&
(aEvent->mEventType == nsIAccessibleEvent::EVENT_NAME_CHANGE ||
aEvent->mEventType == nsIAccessibleEvent::EVENT_TEXT_REMOVED ||
aEvent->mEventType == nsIAccessibleEvent::EVENT_TEXT_INSERTED ||
aEvent->mEventType == nsIAccessibleEvent::EVENT_SHOW ||
aEvent->mEventType == nsIAccessibleEvent::EVENT_HIDE)) {
// Only continue traversing up the tree if it's possible that the parent
// accessible's name can depend on this accessible's name.
Accessible* parent = target->Parent();
while (parent &&
nsTextEquivUtils::HasNameRule(parent, eNameFromSubtreeIfReqRule)) {
// Test possible name dependent parent.
if (nsTextEquivUtils::HasNameRule(parent, eNameFromSubtreeRule)) {
nsAutoString name;
ENameValueFlag nameFlag = parent->Name(name);
// If name is obtained from subtree, fire name change event.
if (nameFlag == eNameFromSubtree) {
nsRefPtr<AccEvent> nameChangeEvent =
new AccEvent(nsIAccessibleEvent::EVENT_NAME_CHANGE, parent);
PushEvent(nameChangeEvent);
}
break;
}
parent = parent->Parent();
}
}
// Associate text change with hide event if it wasn't stolen from hiding
// siblings during coalescence.
AccMutationEvent* showOrHideEvent = downcast_accEvent(aEvent);
if (showOrHideEvent && !showOrHideEvent->mTextChangeEvent)
CreateTextChangeEventFor(showOrHideEvent);
return true;
}
////////////////////////////////////////////////////////////////////////////////
// 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:
CoalesceReorderEvents(tailEvent);
break; // case eCoalesceReorder
case AccEvent::eCoalesceMutationTextChange:
{
for (uint32_t index = tail - 1; index < tail; index--) {
AccEvent* thisEvent = mEvents[index];
if (thisEvent->mEventRule != tailEvent->mEventRule)
continue;
// We don't currently coalesce text change events from show/hide events.
if (thisEvent->mEventType != tailEvent->mEventType)
continue;
// Show events may be duped because of reinsertion (removal is ignored
// because initial insertion is not processed). Ignore initial
// insertion.
if (thisEvent->mAccessible == tailEvent->mAccessible)
thisEvent->mEventRule = AccEvent::eDoNotEmit;
AccMutationEvent* tailMutationEvent = downcast_accEvent(tailEvent);
AccMutationEvent* thisMutationEvent = downcast_accEvent(thisEvent);
if (tailMutationEvent->mParent != thisMutationEvent->mParent)
continue;
// Coalesce text change events for hide and show events.
if (thisMutationEvent->IsHide()) {
AccHideEvent* tailHideEvent = downcast_accEvent(tailEvent);
AccHideEvent* thisHideEvent = downcast_accEvent(thisEvent);
CoalesceTextChangeEventsFor(tailHideEvent, thisHideEvent);
break;
}
AccShowEvent* tailShowEvent = downcast_accEvent(tailEvent);
AccShowEvent* thisShowEvent = downcast_accEvent(thisEvent);
CoalesceTextChangeEventsFor(tailShowEvent, thisShowEvent);
break;
}
} break; // case eCoalesceMutationTextChange
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
// bug 927159).
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::CoalesceReorderEvents(AccEvent* aTailEvent)
{
uint32_t count = mEvents.Length();
for (uint32_t index = count - 2; index < count; index--) {
AccEvent* thisEvent = mEvents[index];
// Skip events of different types and targeted to application accessible.
if (thisEvent->mEventType != aTailEvent->mEventType ||
thisEvent->mAccessible->IsApplication())
continue;
// If thisEvent target is not in document longer, i.e. if it was
// removed from the tree then do not emit the event.
if (!thisEvent->mAccessible->IsDoc() &&
!thisEvent->mAccessible->IsInDocument()) {
thisEvent->mEventRule = AccEvent::eDoNotEmit;
continue;
}
// Coalesce earlier event of the same target.
if (thisEvent->mAccessible == aTailEvent->mAccessible) {
if (thisEvent->mEventRule == AccEvent::eDoNotEmit) {
AccReorderEvent* tailReorder = downcast_accEvent(aTailEvent);
tailReorder->DoNotEmitAll();
} else {
thisEvent->mEventRule = AccEvent::eDoNotEmit;
}
return;
}
// If tailEvent contains thisEvent
// then
// if show or hide of tailEvent contains a grand parent of thisEvent
// then ignore thisEvent and its show and hide events
// otherwise ignore thisEvent but not its show and hide events
Accessible* thisParent = thisEvent->mAccessible;
while (thisParent && thisParent != mDocument) {
if (thisParent->Parent() == aTailEvent->mAccessible) {
AccReorderEvent* tailReorder = downcast_accEvent(aTailEvent);
uint32_t eventType = tailReorder->IsShowHideEventTarget(thisParent);
// Sometimes InvalidateChildren() and
// DocAccessible::CacheChildrenInSubtree() can conspire to reparent an
// accessible in this case no need for mutation events. Se bug 883708
// for details.
if (eventType == nsIAccessibleEvent::EVENT_SHOW ||
eventType == nsIAccessibleEvent::EVENT_HIDE) {
AccReorderEvent* thisReorder = downcast_accEvent(thisEvent);
thisReorder->DoNotEmitAll();
} else {
thisEvent->mEventRule = AccEvent::eDoNotEmit;
}
return;
}
thisParent = thisParent->Parent();
}
// If tailEvent is contained by thisEvent
// then
// if show of thisEvent contains the tailEvent
// then ignore tailEvent
// if hide of thisEvent contains the tailEvent
// then assert
// otherwise ignore tailEvent but not its show and hide events
Accessible* tailParent = aTailEvent->mAccessible;
while (tailParent && tailParent != mDocument) {
if (tailParent->Parent() == thisEvent->mAccessible) {
AccReorderEvent* thisReorder = downcast_accEvent(thisEvent);
AccReorderEvent* tailReorder = downcast_accEvent(aTailEvent);
uint32_t eventType = thisReorder->IsShowHideEventTarget(tailParent);
if (eventType == nsIAccessibleEvent::EVENT_SHOW)
tailReorder->DoNotEmitAll();
else if (eventType == nsIAccessibleEvent::EVENT_HIDE)
NS_ERROR("Accessible tree was modified after it was removed! Huh?");
else
aTailEvent->mEventRule = AccEvent::eDoNotEmit;
return;
}
tailParent = tailParent->Parent();
}
} // for (index)
}
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;
}
void
EventQueue::CoalesceTextChangeEventsFor(AccHideEvent* aTailEvent,
AccHideEvent* aThisEvent)
{
// XXX: we need a way to ignore SplitNode and JoinNode() when they do not
// affect the text within the hypertext.
AccTextChangeEvent* textEvent = aThisEvent->mTextChangeEvent;
if (!textEvent)
return;
if (aThisEvent->mNextSibling == aTailEvent->mAccessible) {
aTailEvent->mAccessible->AppendTextTo(textEvent->mModifiedText);
} else if (aThisEvent->mPrevSibling == aTailEvent->mAccessible) {
uint32_t oldLen = textEvent->GetLength();
aTailEvent->mAccessible->AppendTextTo(textEvent->mModifiedText);
textEvent->mStart -= textEvent->GetLength() - oldLen;
}
aTailEvent->mTextChangeEvent.swap(aThisEvent->mTextChangeEvent);
}
void
EventQueue::CoalesceTextChangeEventsFor(AccShowEvent* aTailEvent,
AccShowEvent* aThisEvent)
{
AccTextChangeEvent* textEvent = aThisEvent->mTextChangeEvent;
if (!textEvent)
return;
if (aTailEvent->mAccessible->IndexInParent() ==
aThisEvent->mAccessible->IndexInParent() + 1) {
// If tail target was inserted after this target, i.e. tail target is next
// sibling of this target.
aTailEvent->mAccessible->AppendTextTo(textEvent->mModifiedText);
} else if (aTailEvent->mAccessible->IndexInParent() ==
aThisEvent->mAccessible->IndexInParent() -1) {
// If tail target was inserted before this target, i.e. tail target is
// previous sibling of this target.
nsAutoString startText;
aTailEvent->mAccessible->AppendTextTo(startText);
textEvent->mModifiedText = startText + textEvent->mModifiedText;
textEvent->mStart -= startText.Length();
}
aTailEvent->mTextChangeEvent.swap(aThisEvent->mTextChangeEvent);
}
void
EventQueue::CreateTextChangeEventFor(AccMutationEvent* aEvent)
{
Accessible* container = aEvent->mAccessible->Parent();
if (!container)
return;
HyperTextAccessible* textAccessible = container->AsHyperText();
if (!textAccessible)
return;
// Don't fire event for the first html:br in an editor.
if (aEvent->mAccessible->Role() == roles::WHITESPACE) {
nsCOMPtr<nsIEditor> editor = textAccessible->GetEditor();
if (editor) {
bool isEmpty = false;
editor->GetDocumentIsEmpty(&isEmpty);
if (isEmpty)
return;
}
}
int32_t offset = textAccessible->GetChildOffset(aEvent->mAccessible);
nsAutoString text;
aEvent->mAccessible->AppendTextTo(text);
if (text.IsEmpty())
return;
aEvent->mTextChangeEvent =
new AccTextChangeEvent(textAccessible, offset, text, aEvent->IsShow(),
aEvent->mIsFromUserInput ? eFromUserInput : eNoUserInput);
}
////////////////////////////////////////////////////////////////////////////////
// EventQueue: event queue
void
EventQueue::ProcessEventQueue()
{
// Process only currently queued events.
nsTArray<nsRefPtr<AccEvent> > events;
events.SwapElements(mEvents);
uint32_t eventCount = events.Length();
#ifdef A11Y_LOG
if (eventCount > 0 && logging::IsEnabled(logging::eEvents)) {
logging::MsgBegin("EVENTS", "events processing");
logging::Address("document", mDocument);
logging::MsgEnd();
}
#endif
for (uint32_t idx = 0; idx < eventCount; idx++) {
AccEvent* event = events[idx];
if (event->mEventRule != AccEvent::eDoNotEmit) {
Accessible* target = event->GetAccessible();
if (!target || target->IsDefunct())
continue;
// Dispatch the focus event if target is still focused.
if (event->mEventType == nsIAccessibleEvent::EVENT_FOCUS) {
FocusMgr()->ProcessFocusEvent(event);
continue;
}
// Dispatch caret moved and text selection change events.
if (event->mEventType == nsIAccessibleEvent::EVENT_TEXT_SELECTION_CHANGED) {
SelectionMgr()->ProcessTextSelChangeEvent(event);
continue;
}
// Fire selected state change events in support to selection events.
if (event->mEventType == nsIAccessibleEvent::EVENT_SELECTION_ADD) {
nsEventShell::FireEvent(event->mAccessible, states::SELECTED,
true, event->mIsFromUserInput);
} else if (event->mEventType == nsIAccessibleEvent::EVENT_SELECTION_REMOVE) {
nsEventShell::FireEvent(event->mAccessible, states::SELECTED,
false, event->mIsFromUserInput);
} else if (event->mEventType == 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);
// Fire text change events.
AccMutationEvent* mutationEvent = downcast_accEvent(event);
if (mutationEvent) {
if (mutationEvent->mTextChangeEvent)
nsEventShell::FireEvent(mutationEvent->mTextChangeEvent);
}
}
if (event->mEventType == nsIAccessibleEvent::EVENT_HIDE)
mDocument->ShutdownChildrenInSubtree(event->mAccessible);
if (!mDocument)
return;
}
}