Bug 764203 - Only notify pivot change if it actually changed. r=davidb

accessible/src/base/nsAccessiblePivot.cpp

@@ -118,7 +118,7 @@ nsAccessiblePivot::SetPosition(nsIAccessible* aPosition)
   mPosition.swap(secondPosition);
   PRInt32 oldStart = mStartOffset, oldEnd = mEndOffset;
   mStartOffset = mEndOffset = -1;
-  NotifyPivotChanged(secondPosition, oldStart, oldEnd);
+  NotifyOfPivotChange(secondPosition, oldStart, oldEnd);
 
   return NS_OK;
 }
@@ -172,7 +172,7 @@ nsAccessiblePivot::SetTextRange(nsIAccessibleText* aTextAccessible,
   nsRefPtr<Accessible> oldPosition = mPosition.forget();
   mPosition = newPosition.forget();
 
-  NotifyPivotChanged(oldPosition, oldStart, oldEnd);
+  NotifyOfPivotChange(oldPosition, oldStart, oldEnd);
 
   return NS_OK;
 }
@@ -199,9 +199,8 @@ nsAccessiblePivot::MoveNext(nsIAccessibleTraversalRule* aRule,
     SearchForward(anchor, aRule, (aArgc > 1) ? aIncludeStart : false, &rv);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  *aResult = accessible;
-  if (*aResult)
-    MovePivotInternal(accessible);
+  if (accessible)
+    *aResult = MovePivotInternal(accessible);
 
   return NS_OK;
 }
@@ -227,9 +226,8 @@ nsAccessiblePivot::MovePrevious(nsIAccessibleTraversalRule* aRule,
     SearchBackward(anchor, aRule, (aArgc > 1) ? aIncludeStart : false, &rv);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  *aResult = accessible;
-  if (*aResult)
-    MovePivotInternal(accessible);
+  if (accessible)
+    *aResult = MovePivotInternal(accessible);
 
   return NS_OK;
 }
@@ -247,9 +245,8 @@ nsAccessiblePivot::MoveFirst(nsIAccessibleTraversalRule* aRule, bool* aResult)
   Accessible* accessible = SearchForward(mRoot, aRule, true, &rv);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  *aResult = accessible;
-  if (*aResult)
-    MovePivotInternal(accessible);
+  if (accessible)
+    *aResult = MovePivotInternal(accessible);
 
   return NS_OK;
 }
@@ -276,9 +273,8 @@ nsAccessiblePivot::MoveLast(nsIAccessibleTraversalRule* aRule, bool* aResult)
   accessible = SearchBackward(lastAccessible, aRule, true, &rv);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  *aResult = accessible;
-  if (*aResult)
-    MovePivotInternal(accessible);
+  if (accessible)
+    *aResult = MovePivotInternal(accessible);
 
   return NS_OK;
 }
@@ -343,7 +339,7 @@ nsAccessiblePivot::IsRootDescendant(Accessible* aAccessible)
   return false;
 }
 
-void
+bool
 nsAccessiblePivot::MovePivotInternal(Accessible* aPosition)
 {
   nsRefPtr<Accessible> oldPosition = mPosition.forget();
@@ -351,7 +347,7 @@ nsAccessiblePivot::MovePivotInternal(Accessible* aPosition)
   PRInt32 oldStart = mStartOffset, oldEnd = mEndOffset;
   mStartOffset = mEndOffset = -1;
 
-  NotifyPivotChanged(oldPosition, oldStart, oldEnd);
+  return NotifyOfPivotChange(oldPosition, oldStart, oldEnd);
 }
 
 Accessible*
@@ -472,15 +468,21 @@ nsAccessiblePivot::SearchForward(Accessible* aAccessible,
   return nsnull;
 }
 
-void
-nsAccessiblePivot::NotifyPivotChanged(Accessible* aOldPosition,
-                                      PRInt32 aOldStart, PRInt32 aOldEnd)
+bool
+nsAccessiblePivot::NotifyOfPivotChange(Accessible* aOldPosition,
+                                       PRInt32 aOldStart, PRInt32 aOldEnd)
 {
+  if (aOldPosition == mPosition &&
+      aOldStart == mStartOffset && aOldEnd == mEndOffset)
+    return false;
+
   nsTObserverArray<nsCOMPtr<nsIAccessiblePivotObserver> >::ForwardIterator iter(mObservers);
   while (iter.HasMore()) {
     nsIAccessiblePivotObserver* obs = iter.GetNext();
     obs->OnPivotChanged(this, aOldPosition, aOldStart, aOldEnd);
   }
+
+  return true;
 }
 
 nsresult

accessible/src/base/nsAccessiblePivot.h

@@ -44,10 +44,11 @@ private:
   void operator = (const nsAccessiblePivot&) MOZ_DELETE;
 
   /*
-   * Notify all observers on a pivot change.
+   * Notify all observers on a pivot change. Return true if it has changed and
+   * observers have been notified.
    */
-  void NotifyPivotChanged(Accessible* aOldAccessible,
-                          PRInt32 aOldStart, PRInt32 aOldEnd);
+  bool NotifyOfPivotChange(Accessible* aOldAccessible,
+                           PRInt32 aOldStart, PRInt32 aOldEnd);
 
   /*
    * Check to see that the given accessible is in the pivot's subtree.
@@ -72,9 +73,9 @@ private:
                              nsresult* aResult);
 
   /*
-   * Update the pivot, and notify observers.
+   * Update the pivot, and notify observers. Return true if it moved.
    */
-  void MovePivotInternal(Accessible* aPosition);
+  bool MovePivotInternal(Accessible* aPosition);
 
   /*
    * The root accessible.