From 98661461cfe256a06fafe9abc4c67caf26f9ae20 Mon Sep 17 00:00:00 2001
From: "aaronleventhal@moonset.net" <aaronleventhal@moonset.net>
Date: Thu, 19 Apr 2007 06:53:34 -0700
Subject: [PATCH] Bug 352205. Swallow duplicate caret move events. r=ginn.chen

---
 accessible/src/base/nsCaretAccessible.cpp | 27 +++++++++++++++++++----
 accessible/src/base/nsCaretAccessible.h   |  4 +++-
 2 files changed, 26 insertions(+), 5 deletions(-)

diff --git a/accessible/src/base/nsCaretAccessible.cpp b/accessible/src/base/nsCaretAccessible.cpp
index 3c953ef87574..ed912c9713db 100644
--- a/accessible/src/base/nsCaretAccessible.cpp
+++ b/accessible/src/base/nsCaretAccessible.cpp
@@ -56,14 +56,16 @@
 NS_IMPL_ISUPPORTS_INHERITED2(nsCaretAccessible, nsLeafAccessible, nsIAccessibleCaret, nsISelectionListener)
 
 nsCaretAccessible::nsCaretAccessible(nsIDOMNode* aDocumentNode, nsIWeakReference* aShell, nsRootAccessible *aRootAccessible):
-nsLeafAccessible(aDocumentNode, aShell), mVisible(PR_TRUE), mCurrentDOMNode(nsnull), mRootAccessible(aRootAccessible)
+nsLeafAccessible(aDocumentNode, aShell), mVisible(PR_TRUE), mLastCaretOffset(-1), mLastNodeWithCaret(nsnull),
+mSelectionControllerNode(nsnull), mRootAccessible(aRootAccessible)
 {
 }
 
 NS_IMETHODIMP nsCaretAccessible::Shutdown()
 {
   mDomSelectionWeak = nsnull;
-  mCurrentDOMNode = nsnull;
+  mLastNodeWithCaret = nsnull;
+  mSelectionControllerNode = nsnull;
   RemoveSelectionListener();
   return NS_OK;
 }
@@ -81,7 +83,8 @@ NS_IMETHODIMP nsCaretAccessible::RemoveSelectionListener()
 
 NS_IMETHODIMP nsCaretAccessible::AttachNewSelectionListener(nsIDOMNode *aCurrentNode)
 {
-  mCurrentDOMNode = aCurrentNode;
+  mSelectionControllerNode = aCurrentNode;
+  mLastNodeWithCaret = nsnull;
 
   // When focus moves such that the caret is part of a new frame selection
   // this removes the old selection listener and attaches a new one for the current focus
@@ -123,7 +126,7 @@ NS_IMETHODIMP nsCaretAccessible::AttachNewSelectionListener(nsIDOMNode *aCurrent
 
 NS_IMETHODIMP nsCaretAccessible::NotifySelectionChanged(nsIDOMDocument *aDoc, nsISelection *aSel, PRInt16 aReason)
 {
-  nsCOMPtr<nsIPresShell> presShell = GetPresShellFor(mCurrentDOMNode);
+  nsCOMPtr<nsIPresShell> presShell = GetPresShellFor(mSelectionControllerNode);
   nsCOMPtr<nsISelection> domSel(do_QueryReferent(mDomSelectionWeak));
   if (!presShell || domSel != aSel)
     return NS_OK;  // Only listening to selection changes in currently focused frame
@@ -181,8 +184,11 @@ NS_IMETHODIMP nsCaretAccessible::NotifySelectionChanged(nsIDOMDocument *aDoc, ns
   nsCOMPtr<nsIDOMNode> focusNode;
   domSel->GetFocusNode(getter_AddRefs(focusNode));
   if (!focusNode) {
+    mLastNodeWithCaret = nsnull;
     return NS_OK; // No selection
   }
+  nsCOMPtr<nsIDOMNode> nodeWithCaret = focusNode;
+
   nsCOMPtr<nsIAccessibleText> textAcc;
   while (focusNode) {
     // Make sure to get the correct starting node for selection events inside XBL content trees
@@ -206,6 +212,19 @@ NS_IMETHODIMP nsCaretAccessible::NotifySelectionChanged(nsIDOMDocument *aDoc, ns
   NS_ASSERTION(textAcc, "No nsIAccessibleText for caret move event!"); // No nsIAccessibleText for caret move event!
   NS_ENSURE_TRUE(textAcc, NS_ERROR_FAILURE);
 
+  PRInt32 caretOffset;
+  textAcc->GetCaretOffset(&caretOffset);
+
+  if (nodeWithCaret == mLastNodeWithCaret && caretOffset == mLastCaretOffset) {
+    PRInt32 selectionCount;
+    textAcc->GetSelectionCount(&selectionCount);   // Don't swallow similar events when selecting text
+    if (!selectionCount) {
+      return NS_OK;  // Swallow duplicate caret event
+    }
+  }
+  mLastCaretOffset = caretOffset;
+  mLastNodeWithCaret = nodeWithCaret;
+
   return mRootAccessible->FireDelayedToolkitEvent(nsIAccessibleEvent::EVENT_TEXT_CARET_MOVED,
                                                   focusNode, nsnull, PR_FALSE);
 }
diff --git a/accessible/src/base/nsCaretAccessible.h b/accessible/src/base/nsCaretAccessible.h
index 3ac49ac29535..4bdbc24b1567 100644
--- a/accessible/src/base/nsCaretAccessible.h
+++ b/accessible/src/base/nsCaretAccessible.h
@@ -91,7 +91,9 @@ public:
 private:
   nsRect mCaretRect;
   PRBool mVisible;
-  nsCOMPtr<nsIDOMNode> mCurrentDOMNode;
+  PRInt32 mLastCaretOffset;
+  nsCOMPtr<nsIDOMNode> mLastNodeWithCaret;
+  nsCOMPtr<nsIDOMNode> mSelectionControllerNode;
   // mListener is not a com pointer. It's a copy of the listener in the nsRootAccessible owner. 
   //See nsRootAccessible.h for details of the lifetime if this listener
   nsRootAccessible *mRootAccessible;