Bug 949518 - keep caret offset syncronized with accessible tree, r=surkov

accessible/src/base/FocusManager.cpp

@@ -364,6 +364,11 @@ FocusManager::ProcessFocusEvent(AccEvent* aEvent)
     logging::FocusNotificationTarget("fire focus event", "Target", target);
 #endif
 
+  // Reset cached caret value. The cache will be updated upon processing the
+  // next caret move event. This ensures that we will return the correct caret
+  // offset before the caret move event is handled.
+  SelectionMgr()->ResetCaretOffset();
+
   nsRefPtr<AccEvent> focusEvent =
     new AccEvent(nsIAccessibleEvent::EVENT_FOCUS, target, aEvent->FromUserInput());
   nsEventShell::FireEvent(focusEvent);

accessible/src/base/SelectionManager.cpp

@@ -6,6 +6,8 @@
 #include "mozilla/a11y/SelectionManager.h"
 
 #include "DocAccessible-inl.h"
+#include "HyperTextAccessible.h"
+#include "HyperTextAccessible-inl.h"
 #include "nsAccessibilityService.h"
 #include "nsAccUtils.h"
 #include "nsCoreUtils.h"
@@ -36,6 +38,12 @@ private:
   ~SelData() {}
 };
 
+SelectionManager::SelectionManager() :
+  mCaretOffset(-1), mAccWithCaret(nullptr)
+{
+
+}
+
 void
 SelectionManager::ClearControlSelectionListener()
 {
@@ -144,10 +152,13 @@ SelectionManager::ProcessTextSelChangeEvent(AccEvent* aEvent)
   if (!caretCntr)
     return;
 
-  int32_t caretOffset = caretCntr->CaretOffset();
-  if (caretOffset != -1) {
+  Selection* selection = caretCntr->DOMSelection();
+  mCaretOffset = caretCntr->DOMPointToOffset(selection->GetFocusNode(),
+                                             selection->FocusOffset());
+  mAccWithCaret = caretCntr;
+  if (mCaretOffset != -1) {
     nsRefPtr<AccCaretMoveEvent> caretMoveEvent =
-      new AccCaretMoveEvent(caretCntr, caretOffset, aEvent->FromUserInput());
+      new AccCaretMoveEvent(caretCntr, mCaretOffset, aEvent->FromUserInput());
     nsEventShell::FireEvent(caretMoveEvent);
   }
 }

accessible/src/base/SelectionManager.h

@@ -20,6 +20,7 @@ class Element;
 namespace a11y {
 
 class AccEvent;
+class HyperTextAccessible;
 
 /**
  * This special accessibility class is for the caret and selection management.
@@ -81,7 +82,38 @@ public:
    */
   void ProcessTextSelChangeEvent(AccEvent* aEvent);
 
+  /**
+   * Gets the current caret offset/hypertext accessible pair. If there is no
+   * current pair, then returns -1 for the offset and a nullptr for the
+   * accessible.
+   */
+  inline HyperTextAccessible* AccessibleWithCaret(int32_t* aCaret)
+  {
+    if (aCaret)
+      *aCaret = mCaretOffset;
+
+    return mAccWithCaret;
+  }
+
+  /**
+   * Update caret offset when it doesn't go through a caret move event.
+   */
+  inline void UpdateCaretOffset(HyperTextAccessible* aItem, int32_t aOffset)
+  {
+    mAccWithCaret = aItem;
+    mCaretOffset = aOffset;
+  }
+
+  inline void ResetCaretOffset()
+  {
+    mCaretOffset = -1;
+    mAccWithCaret = nullptr;
+  }
+
 protected:
+
+  SelectionManager();
+
   /**
    * Process DOM selection change. Fire selection and caret move events.
    */
@@ -90,6 +122,8 @@ protected:
 private:
   // Currently focused control.
   nsWeakFrame mCurrCtrlFrame;
+  int32_t mCaretOffset;
+  HyperTextAccessible* mAccWithCaret;
 };
 
 } // namespace a11y

accessible/src/generic/Accessible.cpp

@@ -2453,6 +2453,8 @@ Accessible::Shutdown()
 
   mContent = nullptr;
   mDoc = nullptr;
+  if (SelectionMgr()->AccessibleWithCaret(nullptr) == this)
+    SelectionMgr()->ResetCaretOffset();
 }
 
 // Accessible protected

accessible/src/generic/HyperTextAccessible-inl.h

@@ -32,6 +32,15 @@ HyperTextAccessible::IsValidRange(int32_t aStartOffset, int32_t aEndOffset)
     endOffset <= CharacterCount();
 }
 
+inline void
+HyperTextAccessible::SetCaretOffset(int32_t aOffset)
+{
+  SetSelectionRange(aOffset, aOffset);
+  // XXX: Force cache refresh until a good solution for AT emulation of user
+  // input is implemented (AccessFu caret movement).
+  SelectionMgr()->UpdateCaretOffset(this, aOffset);
+}
+
 inline bool
 HyperTextAccessible::AddToSelection(int32_t aStartOffset, int32_t aEndOffset)
 {

accessible/src/generic/HyperTextAccessible.cpp

@@ -1162,6 +1162,22 @@ HyperTextAccessible::CaretOffset() const
     return -1;
   }
 
+  // Check cached value.
+  int32_t caretOffset = -1;
+  HyperTextAccessible* text = SelectionMgr()->AccessibleWithCaret(&caretOffset);
+
+  // Use cached value if it corresponds to this accessible.
+  if (caretOffset != -1) {
+    if (text == this)
+      return caretOffset;
+
+    nsINode* textNode = text->GetNode();
+    // Ignore offset if cached accessible isn't a text leaf.
+    if (nsCoreUtils::IsAncestorOf(GetNode(), textNode))
+      return TransformOffset(text,
+        textNode->IsNodeOfType(nsINode::eTEXT) ? caretOffset : 0, false);
+  }
+
   // No caret if the focused node is not inside this DOM node and this DOM node
   // is not inside of focused node.
   FocusManager::FocusDisposition focusDisp =

accessible/src/generic/HyperTextAccessible.h

@@ -302,7 +302,7 @@ public:
    * Get/set caret offset, if no caret then -1.
    */
   int32_t CaretOffset() const;
-  void SetCaretOffset(int32_t aOffset) { SetSelectionRange(aOffset, aOffset); }
+  void SetCaretOffset(int32_t aOffset);
 
   /**
    * Provide the line number for the caret.
@@ -406,6 +406,11 @@ public:
    */
   virtual already_AddRefed<nsIEditor> GetEditor() const;
 
+  /**
+   * Return DOM selection object for the accessible.
+   */
+  dom::Selection* DOMSelection() const;
+
 protected:
   // Accessible
   virtual ENameValueFlag NativeName(nsString& aName) MOZ_OVERRIDE;
@@ -486,10 +491,9 @@ protected:
   // Selection helpers
 
   /**
-   * Return frame/DOM selection object for the accessible.
+   * Return frame selection object for the accessible.
    */
   already_AddRefed<nsFrameSelection> FrameSelection() const;
-  dom::Selection* DOMSelection() const;
 
   /**
    * Return selection ranges within the accessible subtree.

accessible/tests/mochitest/events.js

@@ -1766,8 +1766,7 @@ function textSelectionChecker(aID, aStartOffset, aEndOffset)
   this.check = function textSelectionChecker_check(aEvent)
   {
     if (aStartOffset == aEndOffset) {
-      is(getAccessible(aID, [nsIAccessibleText]).caretOffset, aStartOffset,
-         "Wrong collapsed selection!");
+      ok(true, "Collapsed selection triggered text selection change event.");
     } else {
       testTextGetSelection(aID, aStartOffset, aEndOffset, 0);
     }

accessible/tests/mochitest/events/test_textselchange.html

@@ -46,7 +46,8 @@
                                     new textSelectionChecker("ta1", 0, 1),
                                     { shiftKey: true }));
       gQueue.push(new synthLeftKey("ta1",
-                                    new textSelectionChecker("ta1", 0, 0)));
+                                    [new textSelectionChecker("ta1", 0, 0),
+                                     new caretMoveChecker(0, "ta1")]));
 
       gQueue.invoke(); // Will call SimpleTest.finish();
     }