Bug 1176123 - Add NODE_CHILD_OF/NODE_PARENT_OF relations to mroot. r=surkov

accessible/generic/HyperTextAccessible.cpp

@@ -1755,6 +1755,42 @@ HyperTextAccessible::RemoveChild(Accessible* aAccessible)
   return Accessible::RemoveChild(aAccessible);
 }
 
+Relation
+HyperTextAccessible::RelationByType(RelationType aType)
+{
+  Relation rel = Accessible::RelationByType(aType);
+
+  switch (aType) {
+    case RelationType::NODE_CHILD_OF:
+      if (mContent->IsMathMLElement()) {
+        Accessible* parent = Parent();
+        if (parent) {
+          nsIContent* parentContent = parent->GetContent();
+          if (parentContent->IsMathMLElement(nsGkAtoms::mroot_)) {
+            // Add a relation pointing to the parent <mroot>.
+            rel.AppendTarget(parent);
+          }
+        }
+      }
+      break;
+    case RelationType::NODE_PARENT_OF:
+      if (mContent->IsMathMLElement(nsGkAtoms::mroot_)) {
+        Accessible* base = GetChildAt(0);
+        Accessible* index = GetChildAt(1);
+        if (base && index) {
+          // Append the <mroot> children in the order index, base.
+          rel.AppendTarget(index);
+          rel.AppendTarget(base);
+        }
+      }
+      break;
+    default:
+      break;
+  }
+
+  return rel;
+}
+
 void
 HyperTextAccessible::CacheChildren()
 {

accessible/generic/HyperTextAccessible.h

@@ -62,6 +62,7 @@ public:
 
   virtual void InvalidateChildren() override;
   virtual bool RemoveChild(Accessible* aAccessible) override;
+  virtual Relation RelationByType(RelationType aType) override;
 
   // HyperTextAccessible (static helper method)
 

accessible/tests/mochitest/elm/test_MathMLSpec.html

@@ -125,6 +125,19 @@
 
       obj = {
         role: ROLE_MATHML_ROOT,
+        relations: {
+          RELATION_NODE_PARENT_OF: ["mroot_index", "mroot_base"]
+        },
+        children: [
+          {
+            role: ROLE_MATHML_IDENTIFIER,
+            relations: { RELATION_NODE_CHILD_OF: "mroot" }
+          },
+          {
+            role: ROLE_MATHML_NUMBER,
+            relations: { RELATION_NODE_CHILD_OF: "mroot" }
+          }
+        ]
       };
       testElm("mroot", obj);
 
@@ -386,8 +399,8 @@
       <mn>2</mn>
     </mfrac>
     <mroot id="mroot">
-      <mi>x</mi>
-      <mn>5</mn>
+      <mi id="mroot_base">x</mi>
+      <mn id="mroot_index">5</mn>
     </mroot>
     <mspace width="1em"/>
     <mfenced id="mfenced" close="[" open="]" separators=".">