1 files changed, 335 insertions, 0 deletions
diff --git a/accessible/base/EventQueue.cpp b/accessible/base/EventQueue.cpp
new file mode 100644
index 0000000000..638b2c5b30
--- /dev/null
+++ b/accessible/base/EventQueue.cpp
@@ -0,0 +1,335 @@
+/* -*- 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 "DocAccessibleChild.h"
+#include "nsAccessibilityService.h"
+#include "nsTextEquivUtils.h"
+#ifdef A11Y_LOG
+#  include "Logging.h"
+#endif
+
+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!");
+
+  // XXX(Bug 1631371) Check if this should use a fallible operation as it
+  // 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)) {
+    PushNameChange(aEvent->mAccessible);
+  }
+  return true;
+}
+
+bool EventQueue::PushNameChange(Accessible* aTarget) {
+  // 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.
+  if (aTarget->HasNameDependentParent()) {
+    // 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 = aTarget->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) {
+          RefPtr<AccEvent> nameChangeEvent =
+              new AccEvent(nsIAccessibleEvent::EVENT_NAME_CHANGE, parent);
+          return PushEvent(nameChangeEvent);
+        }
+        break;
+      }
+      parent = parent->Parent();
+    }
+  }
+  return false;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// 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<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
+}
+
+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);
+
+  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);
+    }
+
+    if (!mDocument) return;
+  }
+}
+
+}  // namespace a11y
+}  // namespace mozilla