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<Accessible*> 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
// 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
}
