Various fixes for aria-activedescendant.

third_party/WebKit/Source/modules/accessibility/AXObject.cpp

 /*
  * Copyright (C) 2008, 2009, 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 312 matching lines @@
     "scrollbar",
     "slider",
     "spinbutton",
     "status",
     "tab",
     "tabpanel",
     "textbox",
     "timer",
     "tooltip",
     "treeitem",
-    // Composite user interface widgets.  This list is also from w3.org site refrerenced above.
+    // Composite user interface widgets.
+    // This list is also from the w3.org site referenced above.
     "combobox",
     "grid",
     "listbox",
     "menu",
     "menubar",
     "radiogroup",
     "tablist",
     "tree",
     "treegrid"
 };
@@ skipping 37 matching lines @@
     , m_role(UnknownRole)
     , m_lastKnownIsIgnoredValue(DefaultBehavior)
     , m_parent(nullptr)
     , m_lastModificationCount(-1)
     , m_cachedIsIgnored(false)
     , m_cachedIsInertOrAriaHidden(false)
     , m_cachedIsDescendantOfLeafNode(false)
     , m_cachedIsDescendantOfDisabledNode(false)
     , m_cachedHasInheritedPresentationalRole(false)
     , m_cachedIsPresentationalChild(false)
+    , m_cachedAncestorExposesActiveDescendant(false)
     , m_cachedLiveRegionRoot(nullptr)
     , m_axObjectCache(&axObjectCache)
 {
     ++s_numberOfLiveAXObjects;
 }
 
 AXObject::~AXObject()
 {
     ASSERT(isDetached());
     --s_numberOfLiveAXObjects;
@@ skipping 113 matching lines @@
     m_lastModificationCount = cache.modificationCount();
     m_cachedIsInertOrAriaHidden = computeIsInertOrAriaHidden();
     m_cachedIsDescendantOfLeafNode = (leafNodeAncestor() != 0);
     m_cachedIsDescendantOfDisabledNode = (disabledAncestor() != 0);
     m_cachedHasInheritedPresentationalRole = (inheritsPresentationalRoleFrom() != 0);
     m_cachedIsPresentationalChild = (ancestorForWhichThisIsAPresentationalChild() != 0);
     m_cachedIsIgnored = computeAccessibilityIsIgnored();
     m_cachedLiveRegionRoot = isLiveRegion() ?
         this :
         (parentObjectIfExists() ? parentObjectIfExists()->liveRegionRoot() : 0);
+    m_cachedAncestorExposesActiveDescendant = computeAncestorExposesActiveDescendant();
 }
 
 bool AXObject::accessibilityIsIgnoredByDefault(IgnoredReasons* ignoredReasons) const
 {
     return defaultObjectInclusion(ignoredReasons) == IgnoreObject;
 }
 
 AXObjectInclusion AXObject::accessibilityPlatformIncludesObject() const
 {
     if (isMenuListPopup() || isMenuListOption())
@@ skipping 135 matching lines @@
     updateCachedAttributeValuesIfNeeded();
     return m_cachedHasInheritedPresentationalRole;
 }
 
 bool AXObject::isPresentationalChild() const
 {
     updateCachedAttributeValuesIfNeeded();
     return m_cachedIsPresentationalChild;
 }
 
+bool AXObject::ancestorExposesActiveDescendant() const
+{
+    updateCachedAttributeValuesIfNeeded();
+    return m_cachedAncestorExposesActiveDescendant;
+}
+
+bool AXObject::computeAncestorExposesActiveDescendant() const
+{
+    for (const AXObject* object = this; object; object = object->parentObjectUnignored()) {

[dmazzoni, 2016/04/06 15:51:12]

Should this return true for itself or only for an ancestor? I'd expect it to
only return true if activeDescendant is set on an ancestor, but it actually
returns true for the object it's called on if that object has an
activeDescendant.

Also, I think it should call ancestorExposesActiveDescendant() recursively
because then you can take advantage of memoization and make it log(n) times
faster. So something like this:

    AXObject* parent = parentObjectUnignored();
    if (!parent)
        return false;

    if (parent->supportsActiveDescendant() &&
!parent->getAttribute(aria_activedescendantAttr).isEmpty())
        return true;

    return parent->ancestorExposesActiveDescendant();

+        if (object->supportsActiveDescendant()
+            && !object->getAttribute(aria_activedescendantAttr).isEmpty()) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
 // Simplify whitespace, but preserve a single leading and trailing whitespace character if it's present.
 // static
 String AXObject::collapseWhitespace(const String& str)
 {
     StringBuilder result;
     if (!str.isEmpty() && isHTMLSpace<UChar>(str[0]))
         result.append(' ');
     result.append(str.simplifyWhiteSpace(isHTMLSpace<UChar>));
     if (!str.isEmpty() && isHTMLSpace<UChar>(str[str.length() - 1]))
         result.append(' ');
@@ skipping 283 matching lines @@
         return false;
 
     return equalIgnoringCase(getAttribute(aria_multilineAttr), "true");
 }
 
 bool AXObject::ariaPressedIsPresent() const
 {
     return !getAttribute(aria_pressedAttr).isEmpty();
 }
 
+bool AXObject::supportsActiveDescendant() const
+{
+    // According to the ARIA Spec, all ARIA composite widgets, ARIA text boxes
+    // and ARIA groups should be able to expose an active descendant.
+    // Implicitly, <input> and <textarea> elements should also have this ability.
+    switch (ariaRoleAttribute()) {
+    case ComboBoxRole:
+    case GridRole:
+    case GroupRole:
+    case ListBoxRole:
+    case MenuRole:
+    case MenuBarRole:
+    case RadioGroupRole:
+    case RowRole:
+    case SearchBoxRole:
+    case TabListRole:
+    case TextFieldRole:
+    case ToolbarRole:
+    case TreeRole:
+    case TreeGridRole:
+        return true;
+    default:
+        return false;
+    }
+}
+
 bool AXObject::supportsARIAAttributes() const
 {
     return isLiveRegion()
         || supportsARIADragging()
         || supportsARIADropping()
         || supportsARIAFlowTo()
         || supportsARIAOwns()
         || hasAttribute(aria_labelAttr);
 }
 
@@ skipping 693 matching lines @@
 
 DEFINE_TRACE(AXObject)
 {
     visitor->trace(m_children);
     visitor->trace(m_parent);
     visitor->trace(m_cachedLiveRegionRoot);
     visitor->trace(m_axObjectCache);
 }
 
 } // namespace blink