Merge r228417 - AX: defer focusedUIElement notifications

https://bugs.webkit.org/show_bug.cgi?id=182643 <rdar://problem/37394310> Reviewed by Zalan Bujtas. Source/WebCore: Deferring focus changes for accessibility has a number of benefits. 1) Reduces the chance of calling into layout during layout. 2) Coalesces multiple focus notifications that would be needlessly sent. 3) Improves performance by not calling out to the accessibility notification machinery during layout. In this patch, I also started making more AXObjectCache calls private. This will reduce the chance that clients will call into AXObjectCache during unexpected times. * accessibility/AXObjectCache.cpp: (WebCore::AXObjectCache::deferFocusedUIElementChangeIfNeeded): (WebCore::conditionallyAddNodeToFilterList): (WebCore::filterVectorPairForRemoval): (WebCore::filterMapForRemoval): (WebCore::filterListForRemoval): (WebCore::AXObjectCache::prepareForDocumentDestruction): (WebCore::AXObjectCache::performDeferredCacheUpdate): * accessibility/AXObjectCache.h: * dom/Document.cpp: (WebCore::Document::setFocusedElement): LayoutTests: * accessibility/mac/aria-menu-item-selected-notification.html: Rewrite test to accomodate that focus changes happen asynchronously. * accessibility/mac/selection-notification-focus-change-expected.txt: * platform/mac-wk2/accessibility/mac/selection-notification-focus-change-expected.txt: The order of notifications is different now that focus changes happen later.
WebKit · Feb 20, 2018 · f8fab14 · f8fab14
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diff --git a/LayoutTests/ChangeLog b/LayoutTests/ChangeLog
@@ -1,3 +1,17 @@
+2018-02-12  Chris Fleizach  <cfleizach@apple.com>
+
+        AX: defer focusedUIElement notifications
+        https://bugs.webkit.org/show_bug.cgi?id=182643
+        <rdar://problem/37394310>
+
+        Reviewed by Zalan Bujtas.
+
+        * accessibility/mac/aria-menu-item-selected-notification.html:
+             Rewrite test to accomodate that focus changes happen asynchronously.
+        * accessibility/mac/selection-notification-focus-change-expected.txt:
+        * platform/mac-wk2/accessibility/mac/selection-notification-focus-change-expected.txt:
+             The order of notifications is different now that focus changes happen later.
+
 2018-02-12  John Wilander  <wilander@apple.com>
 
         Resource Load Statistics: Classify resources as prevalent based on redirects to other prevalent resources

diff --git a/LayoutTests/accessibility/mac/aria-menu-item-selected-notification.html b/LayoutTests/accessibility/mac/aria-menu-item-selected-notification.html
@@ -46,14 +46,20 @@
         // Trigger notification through focus.
         document.getElementById("item1").focus();
 
-        // Trigger notification through aria-selected.
-        document.getElementById("item2").setAttribute("aria-selected", "true");
+        setTimeout(function() {
+            // Trigger notification through aria-selected.
+            document.getElementById("item2").setAttribute("aria-selected", "true");
 
-        // Ensure we don't get a notification when aria-selected is false.
-        document.getElementById("item2").setAttribute("aria-selected", "false");
+            setTimeout(function() {
+                // Ensure we don't get a notification when aria-selected is false.
+                document.getElementById("item2").setAttribute("aria-selected", "false");
 
-        // Trigger another notification through focus to ensure we don't
-        document.getElementById("item3").focus();
+                setTimeout(function() {
+                    // Trigger another notification through focus to ensure we don't
+                    document.getElementById("item3").focus();
+                }, 1);
+            }, 1);
+        }, 1);
     }
 
 </script>

diff --git a/LayoutTests/accessibility/mac/selection-notification-focus-change-expected.txt b/LayoutTests/accessibility/mac/selection-notification-focus-change-expected.txt
@@ -16,9 +16,9 @@ accessibilityController.accessibleElementById("1").takeFocus()
 Received AXFocusChanged
 
 eventSender.keyDown(tabCharacter)
-Received AXFocusChanged
 Received AXSelectedTextChanged
 PASS userInfo["AXTextSelectionChangedFocus"] is true
+Received AXFocusChanged
 Received AXSelectedTextChanged
 PASS userInfo["AXTextSelectionChangedFocus"] is true
 PASS successfullyParsed is true

diff --git a/...Tests/platform/mac-wk2/accessibility/mac/selection-notification-focus-change-expected.txt b/...Tests/platform/mac-wk2/accessibility/mac/selection-notification-focus-change-expected.txt
@@ -7,18 +7,18 @@ PASS webArea.addNotificationListener(notificationCallback) is true
 eventSender.keyDown(tabCharacter);
 Received AXSelectedTextChanged
 PASS userInfo["AXTextSelectionChangedFocus"] is true
-Received AXFocusChanged
 Received AXSelectedTextChanged
 PASS userInfo["AXTextSelectionChangedFocus"] is true
+Received AXFocusChanged
 
 PASS accessibilityController.accessibleElementById("1").isFocusable is true
 accessibilityController.accessibleElementById("1").takeFocus()
 Received AXFocusChanged
 
 eventSender.keyDown(tabCharacter)
-Received AXFocusChanged
 Received AXSelectedTextChanged
 PASS userInfo["AXTextSelectionChangedFocus"] is true
+Received AXFocusChanged
 PASS successfullyParsed is true
 
 TEST COMPLETE

diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
@@ -1,3 +1,31 @@
+2018-02-12  Chris Fleizach  <cfleizach@apple.com>
+
+        AX: defer focusedUIElement notifications
+        https://bugs.webkit.org/show_bug.cgi?id=182643
+        <rdar://problem/37394310>
+
+        Reviewed by Zalan Bujtas.
+
+        Deferring focus changes for accessibility has a number of benefits.
+            1) Reduces the chance of calling into layout during layout.
+            2) Coalesces multiple focus notifications that would be needlessly sent.
+            3) Improves performance by not calling out to the accessibility notification machinery during layout.
+
+        In this patch, I also started making more AXObjectCache calls private. This will reduce the chance that clients
+        will call into AXObjectCache during unexpected times.
+
+        * accessibility/AXObjectCache.cpp:
+        (WebCore::AXObjectCache::deferFocusedUIElementChangeIfNeeded):
+        (WebCore::conditionallyAddNodeToFilterList):
+        (WebCore::filterVectorPairForRemoval):
+        (WebCore::filterMapForRemoval):
+        (WebCore::filterListForRemoval):
+        (WebCore::AXObjectCache::prepareForDocumentDestruction):
+        (WebCore::AXObjectCache::performDeferredCacheUpdate):
+        * accessibility/AXObjectCache.h:
+        * dom/Document.cpp:
+        (WebCore::Document::setFocusedElement):
+
 2018-02-12  John Wilander  <wilander@apple.com>
 
         Resource Load Statistics: Classify resources as prevalent based on redirects to other prevalent resources

diff --git a/Source/WebCore/accessibility/AXObjectCache.cpp b/Source/WebCore/accessibility/AXObjectCache.cpp
@@ -1017,6 +1017,14 @@ void AXObjectCache::handleMenuItemSelected(Node* node)
     postNotification(getOrCreate(node), &document(), AXMenuListItemSelected);
 }
 
+void AXObjectCache::deferFocusedUIElementChangeIfNeeded(Node* oldNode, Node* newNode)
+{
+    if (nodeAndRendererAreValid(newNode) && rendererNeedsDeferredUpdate(*newNode->renderer()))
+        m_deferredFocusedNodeChange.append({ oldNode, newNode });
+    else
+        handleFocusedUIElementChanged(oldNode, newNode);
+}
+
 void AXObjectCache::handleFocusedUIElementChanged(Node* oldNode, Node* newNode)
 {
     handleMenuItemSelected(newNode);
@@ -2777,25 +2785,33 @@ const Element* AXObjectCache::rootAXEditableElement(const Node* node)
     return result;
 }
 
-template<typename T, typename U>
-static void filterMapForRemoval(const HashMap<T, U>& list, const Document& document, HashSet<Node*>& nodesToRemove)
+static void conditionallyAddNodeToFilterList(Node* node, const Document& document, HashSet<Node*>& nodesToRemove)
 {
-    for (auto& entry : list) {
-        auto* node = entry.key;
-        if (node->isConnected() && &node->document() != &document)
-            continue;
+    if (node && (!node->isConnected() || &node->document() == &document))
         nodesToRemove.add(node);
+}
+
+template<typename T>
+static void filterVectorPairForRemoval(const Vector<std::pair<T, T>>& list, const Document& document, HashSet<Node*>& nodesToRemove)
+{
+    for (auto& entry : list) {
+        conditionallyAddNodeToFilterList(entry.first, document, nodesToRemove);
+        conditionallyAddNodeToFilterList(entry.second, document, nodesToRemove);
     }
 }
+
+template<typename T, typename U>
+static void filterMapForRemoval(const HashMap<T, U>& list, const Document& document, HashSet<Node*>& nodesToRemove)
+{
+    for (auto& entry : list)
+        conditionallyAddNodeToFilterList(entry.key, document, nodesToRemove);
+}
 
 template<typename T>
 static void filterListForRemoval(const ListHashSet<T>& list, const Document& document, HashSet<Node*>& nodesToRemove)
 {
-    for (auto* node : list) {
-        if (node->isConnected() && &node->document() != &document)
-            continue;
-        nodesToRemove.add(node);
-    }
+    for (auto* node : list)
+        conditionallyAddNodeToFilterList(node, document, nodesToRemove);
 }
 
 void AXObjectCache::prepareForDocumentDestruction(const Document& document)
@@ -2808,6 +2824,7 @@ void AXObjectCache::prepareForDocumentDestruction(const Document& document)
     filterListForRemoval(m_deferredSelectedChildredChangedList, document, nodesToRemove);
     filterMapForRemoval(m_deferredTextFormControlValue, document, nodesToRemove);
     filterMapForRemoval(m_deferredAttributeChange, document, nodesToRemove);
+    filterVectorPairForRemoval(m_deferredFocusedNodeChange, document, nodesToRemove);
 
     for (auto* node : nodesToRemove)
         remove(*node);
@@ -2851,6 +2868,10 @@ void AXObjectCache::performDeferredCacheUpdate()
     for (auto& deferredAttributeChangeContext : m_deferredAttributeChange)
         handleAttributeChange(deferredAttributeChangeContext.value, deferredAttributeChangeContext.key);
     m_deferredAttributeChange.clear();
+
+    for (auto& deferredFocusedChangeContext : m_deferredFocusedNodeChange)
+        handleFocusedUIElementChanged(deferredFocusedChangeContext.first, deferredFocusedChangeContext.second);
+    m_deferredFocusedNodeChange.clear();
 }
 
 void AXObjectCache::deferRecomputeIsIgnoredIfNeeded(Element* element)

diff --git a/Source/WebCore/accessibility/AXObjectCache.h b/Source/WebCore/accessibility/AXObjectCache.h
@@ -168,21 +168,13 @@ class AXObjectCache {
     void childrenChanged(RenderObject*, RenderObject* newChild = nullptr);
     void childrenChanged(AccessibilityObject*);
     void checkedStateChanged(Node*);
-    void selectedChildrenChanged(Node*);
-    void selectedChildrenChanged(RenderObject*);
-    // Called by a node when text or a text equivalent (e.g. alt) attribute is changed.
-    void textChanged(Node*);
     // Called when a node has just been attached, so we can make sure we have the right subclass of AccessibilityObject.
     void updateCacheAfterNodeIsAttached(Node*);
 
-    void handleActiveDescendantChanged(Node*);
-    void handleAriaRoleChanged(Node*);
-    void handleFocusedUIElementChanged(Node* oldFocusedNode, Node* newFocusedNode);
+    void deferFocusedUIElementChangeIfNeeded(Node* oldFocusedNode, Node* newFocusedNode);
     void handleScrolledToAnchor(const Node* anchorNode);
-    void handleAriaExpandedChange(Node*);
     void handleScrollbarUpdate(ScrollView*);
 
-    void handleModalChange(Node*);
     Node* modalNode();
 
     void deferAttributeChangeIfNeeded(const QualifiedName&, Element*);
@@ -411,11 +403,20 @@ class AXObjectCache {
     void handleMenuItemSelected(Node*);
     void handleAttributeChange(const QualifiedName&, Element*);
     bool shouldProcessAttributeChange(const QualifiedName&, Element*);
-
+    void selectedChildrenChanged(Node*);
+    void selectedChildrenChanged(RenderObject*);
+    // Called by a node when text or a text equivalent (e.g. alt) attribute is changed.
+    void textChanged(Node*);
+    void handleActiveDescendantChanged(Node*);
+    void handleAriaRoleChanged(Node*);
+    void handleAriaExpandedChange(Node*);
+    void handleFocusedUIElementChanged(Node* oldFocusedNode, Node* newFocusedNode);
+
     // aria-modal related
     void findModalNodes();
     void updateCurrentModalNode();
     bool isNodeVisible(Node*) const;
+    void handleModalChange(Node*);
 
     Document& m_document;
     HashMap<AXID, RefPtr<AccessibilityObject>> m_objects;
@@ -449,6 +450,7 @@ class AXObjectCache {
     ListHashSet<Element*> m_deferredSelectedChildredChangedList;
     HashMap<Element*, String> m_deferredTextFormControlValue;
     HashMap<Element*, QualifiedName> m_deferredAttributeChange;
+    Vector<std::pair<Node*, Node*>> m_deferredFocusedNodeChange;
     bool m_isSynchronizingSelection { false };
     bool m_performingDeferredCacheUpdate { false };
 };

diff --git a/Source/WebCore/dom/Document.cpp b/Source/WebCore/dom/Document.cpp
@@ -3972,7 +3972,7 @@ bool Document::setFocusedElement(Element* element, FocusDirection direction, Foc
     if (!focusChangeBlocked && m_focusedElement) {
         // Create the AXObject cache in a focus change because GTK relies on it.
         if (AXObjectCache* cache = axObjectCache())
-            cache->handleFocusedUIElementChanged(oldFocusedElement.get(), newFocusedElement.get());
+            cache->deferFocusedUIElementChangeIfNeeded(oldFocusedElement.get(), newFocusedElement.get());
     }
 
     if (!focusChangeBlocked && page())