Bug 786143 - inherit aria-hidden through subtree, r=yzen

accessible/base/ARIAMap.cpp

@@ -711,7 +711,7 @@ static const AttrCharacteristics gWAIUnivAttrMap[] = {
   {&nsGkAtoms::aria_flowto,            ATTR_BYPASSOBJ                 | ATTR_GLOBAL },
   {&nsGkAtoms::aria_grabbed,                            ATTR_VALTOKEN | ATTR_GLOBAL },
   {&nsGkAtoms::aria_haspopup,          ATTR_BYPASSOBJ | ATTR_VALTOKEN | ATTR_GLOBAL },
-  {&nsGkAtoms::aria_hidden,   ATTR_BYPASSOBJ_IF_FALSE | ATTR_VALTOKEN | ATTR_GLOBAL },
+  {&nsGkAtoms::aria_hidden,            ATTR_BYPASSOBJ | ATTR_VALTOKEN | ATTR_GLOBAL }, /* handled special way */
   {&nsGkAtoms::aria_invalid,           ATTR_BYPASSOBJ | ATTR_VALTOKEN | ATTR_GLOBAL },
   {&nsGkAtoms::aria_label,             ATTR_BYPASSOBJ                 | ATTR_GLOBAL },
   {&nsGkAtoms::aria_labelledby,        ATTR_BYPASSOBJ                 | ATTR_GLOBAL },
@@ -798,6 +798,15 @@ aria::AttrCharacteristicsFor(nsIAtom* aAtom)
   return 0;
 }
 
+bool
+aria::HasDefinedARIAHidden(nsIContent* aContent)
+{
+  return aContent &&
+    nsAccUtils::HasDefinedARIAToken(aContent, nsGkAtoms::aria_hidden) &&
+    !aContent->AttrValueIs(kNameSpaceID_None, nsGkAtoms::aria_hidden,
+                           nsGkAtoms::_false, eCaseMatters);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // AttrIterator class
 

accessible/base/ARIAMap.h

@@ -227,6 +227,11 @@ uint64_t UniversalStatesFor(mozilla::dom::Element* aElement);
  */
 uint8_t AttrCharacteristicsFor(nsIAtom* aAtom);
 
+/**
+ * Return true if the element has defined aria-hidden.
+ */
+bool HasDefinedARIAHidden(nsIContent* aContent);
+
  /**
   * Represents a simple enumerator for iterating through ARIA attributes
   * exposed as object attributes on a given accessible.

accessible/base/nsAccessiblePivot.cpp

@@ -892,11 +892,7 @@ RuleCache::ApplyFilter(Accessible* aAccessible, uint16_t* aResult)
       return NS_OK;
 
     if (nsIAccessibleTraversalRule::PREFILTER_ARIA_HIDDEN & mPreFilter) {
-      nsIContent* content = aAccessible->GetContent();
-      if (content &&
-          nsAccUtils::HasDefinedARIAToken(content, nsGkAtoms::aria_hidden) &&
-          !content->AttrValueIs(kNameSpaceID_None, nsGkAtoms::aria_hidden,
-                                nsGkAtoms::_false, eCaseMatters)) {
+      if (aAccessible->IsARIAHidden()) {
         *aResult |= nsIAccessibleTraversalRule::FILTER_IGNORE_SUBTREE;
         return NS_OK;
       }

accessible/generic/Accessible.cpp

@@ -873,6 +873,11 @@ Accessible::Attributes()
   while(attribIter.Next(name, value))
     attributes->SetStringProperty(NS_ConvertUTF16toUTF8(name), value, unused);
 
+  if (IsARIAHidden()) {
+    nsAccUtils::SetAccAttr(attributes, nsGkAtoms::hidden,
+                           NS_LITERAL_STRING("true"));
+  }
+
   // If there is no aria-live attribute then expose default value of 'live'
   // object attribute used for ARIA role of this accessible.
   if (mRoleMapEntry) {
@@ -1920,6 +1925,9 @@ Accessible::BindToParent(Accessible* aParent, uint32_t aIndexInParent)
     mContextFlags |= eHasNameDependentParent;
   else
     mContextFlags &= ~eHasNameDependentParent;
+
+  if (mParent->IsARIAHidden() || aria::HasDefinedARIAHidden(mContent))
+    SetARIAHidden(true);
 }
 
 // Accessible protected
@@ -2377,6 +2385,20 @@ Accessible::ContainerWidget() const
   return nullptr;
 }
 
+void
+Accessible::SetARIAHidden(bool aIsDefined)
+{
+  if (aIsDefined)
+    mContextFlags |= eARIAHidden;
+  else
+    mContextFlags &= ~eARIAHidden;
+
+  uint32_t length = mChildren.Length();
+  for (uint32_t i = 0; i < length; i++) {
+    mChildren[i]->SetARIAHidden(aIsDefined);
+  }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Accessible protected methods
 

accessible/generic/Accessible.h

@@ -889,6 +889,13 @@ public:
   bool HasNameDependentParent() const
     { return mContextFlags & eHasNameDependentParent; }
 
+  /**
+   * Return true if aria-hidden="true" is applied to the accessible or inherited
+   * from the parent.
+   */
+  bool IsARIAHidden() const { return mContextFlags & eARIAHidden; }
+  void SetARIAHidden(bool aIsDefined);
+
 protected:
 
   virtual ~Accessible();
@@ -975,8 +982,9 @@ protected:
    */
   enum ContextFlags {
     eHasNameDependentParent = 1 << 0, // Parent's name depends on this accessible.
+    eARIAHidden = 1 << 1,
 
-    eLastContextFlag = eHasNameDependentParent
+    eLastContextFlag = eARIAHidden
   };
 
 protected:
@@ -1082,7 +1090,7 @@ protected:
 
   static const uint8_t kChildrenFlagsBits = 2;
   static const uint8_t kStateFlagsBits = 9;
-  static const uint8_t kContextFlagsBits = 1;
+  static const uint8_t kContextFlagsBits = 2;
   static const uint8_t kTypeBits = 6;
   static const uint8_t kGenericTypesBits = 13;
 

accessible/generic/DocAccessible.cpp

@@ -955,6 +955,22 @@ DocAccessible::ARIAAttributeChanged(Accessible* aAccessible, nsIAtom* aAttribute
 
   nsIContent* elm = aAccessible->GetContent();
 
+  // Update aria-hidden flag for the whole subtree iff aria-hidden is changed
+  // on the root, i.e. ignore any affiliated aria-hidden changes in the subtree
+  // of top aria-hidden.
+  if (aAttribute == nsGkAtoms::aria_hidden) {
+    bool isDefined = aria::HasDefinedARIAHidden(elm);
+    if (isDefined != aAccessible->IsARIAHidden() &&
+        !aAccessible->Parent()->IsARIAHidden()) {
+      aAccessible->SetARIAHidden(isDefined);
+
+      nsRefPtr<AccEvent> event =
+        new AccObjectAttrChangedEvent(aAccessible, aAttribute);
+      FireDelayedEvent(event);
+    }
+    return;
+  }
+
   if (aAttribute == nsGkAtoms::aria_checked ||
       (aAccessible->IsButton() &&
        aAttribute == nsGkAtoms::aria_pressed)) {

accessible/tests/mochitest/events/test_aria_objattr.html

@@ -11,6 +11,8 @@
 
   <script type="application/javascript"
           src="../common.js"></script>
+  <script type="application/javascript"
+          src="../attributes.js"></script>
   <script type="application/javascript"
           src="../events.js"></script>
 
@@ -40,6 +42,23 @@
       };
     }
 
+    function updateARIAHidden(aID, aIsDefined, aChildId)
+    {
+      this.__proto__ = new updateAttribute(aID, "aria-hidden",
+                                           aIsDefined ? "true" : "false");
+
+      this.finalCheck = function updateARIAHidden()
+      {
+        if (aIsDefined) {
+          testAttrs(aID, {"hidden" : "true"}, true);
+          testAttrs(aChildId, {"hidden" : "true"}, true);
+        } else {
+          testAbsentAttrs(aID, { "hidden": "true"});
+          testAbsentAttrs(aChildId, { "hidden": "true"});
+        }
+      }
+    }
+
     // Debug stuff.
     // gA11yEventDumpID = "eventdump";
     //gA11yEventDumpToConsole = true;
@@ -48,7 +67,8 @@
     {
       gQueue = new eventQueue();
 
-      gQueue.push(new updateAttribute("hideable", "aria-hidden", "true"));
+      gQueue.push(new updateARIAHidden("hideable", true, "hideable_child"));
+      gQueue.push(new updateARIAHidden("hideable", false, "hideable_child"));
 
       gQueue.push(new updateAttribute("sortable", "aria-sort", "ascending"));
 
@@ -89,7 +109,7 @@
   </pre>
   <div id="eventdump"></div>
 
-  <div id="hideable"><div>Hi</div><div>there</div></div>
+  <div id="hideable"><div id="hideable_child">Hi</div><div>there</div></div>
 
   <div id="sortable" role="columnheader" aria-sort="none">aria-sort</div>