Naive functionality for AXNode PosInSet and SetSize

Added functionality for AXNode::PosInSet(), which determines a node's
position within an ordered container, and AXNode::SetSize, which
determines the total number of elements within the node's container.

Change-Id: Idd1849891db8cb96c30edda4d4b85b9a206220f2
Reviewed-on: https://chromium-review.googlesource.com/c/1336327
Commit-Queue: Akihiro Ota <akihiroota@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608241}

ui/accessibility/ax_node.cc

@@ -473,4 +473,68 @@ void AXNode::IdVectorToNodeVector(std::vector<int32_t>& ids,
   }
 }
 
+bool AXNode::IsPosInSetUsedInRole() const {
+  switch (data().role) {
+    case ax::mojom::Role::kArticle:
+    case ax::mojom::Role::kListItem:
+    case ax::mojom::Role::kMenuItem:
+    case ax::mojom::Role::kMenuItemRadio:
+    case ax::mojom::Role::kTab:
+    case ax::mojom::Role::kMenuItemCheckBox:
+    case ax::mojom::Role::kTreeItem:
+    case ax::mojom::Role::kListBoxOption:
+    case ax::mojom::Role::kRadioButton:
+      return true;
+
+    default:
+      return false;
+  }
+}
+
+// Finds the position of this node within a list.
+// Only takes into account elements that have same role as node.
+int32_t AXNode::PosInSet() const {
+  AXNode* parent = GetUnignoredParent();
+
+  // Error checks
+  if (!parent)
+    return 0;
+  if (parent->data().role != ax::mojom::Role::kList)
+    return 0;
+  if (!IsPosInSetUsedInRole())
+    return 0;
+
+  int position = 0;
+  for (int i = 0; i < parent->GetUnignoredChildCount(); ++i) {
+    AXNode* candidate = parent->GetUnignoredChildAtIndex(i);
+    if (candidate->data().role == data().role)
+      ++position;
+    if (candidate == this)
+      return position;
+  }
+  return 0;
+}
+
+// Finds the total number of elements of the list this node is contained within.
+// Only counts the elements that have the same role as node.
+int32_t AXNode::SetSize() const {
+  AXNode* parent = GetUnignoredParent();
+
+  // Error checks
+  if (!parent)
+    return 0;
+  if (parent->data().role != ax::mojom::Role::kList)
+    return 0;
+  if (!IsPosInSetUsedInRole())
+    return 0;
+
+  int count = 0;
+  for (int i = 0; i < parent->GetUnignoredChildCount(); ++i) {
+    AXNode* child = parent->GetUnignoredChildAtIndex(i);
+    if (child->data().role == data().role)
+      ++count;
+  }
+  return count;
+}
+
 }  // namespace ui

ui/accessibility/ax_node.h

@@ -181,6 +181,15 @@ class AX_EXPORT AXNode final {
     return data().GetHtmlAttribute(attribute, value);
   }
 
+  // Returns the position of node within a list. Returns 1-based index if
+  // contained within a list, and 0 if not.
+  int32_t PosInSet() const;
+  // Returns the total number of nodes in the same list as node. Returns 0
+  // if the node is not contained wihtin a list.
+  int32_t SetSize() const;
+  // Returns true if the aria-posinset attribute is used in node's role
+  bool IsPosInSetUsedInRole() const;
+
   const std::string& GetInheritedStringAttribute(
       ax::mojom::StringAttribute attribute) const;
   base::string16 GetInheritedString16Attribute(

ui/accessibility/ax_tree_unittest.cc

@@ -1472,4 +1472,83 @@ TEST(AXTreeTest, ChildTreeIds) {
   EXPECT_EQ(0U, child_tree_93_nodes.size());
 }
 
+// Simple test for PosInSet and SetSize.
+TEST(AXTreeTest, GetPosInSetSetSize) {
+  AXTreeUpdate tree_update;
+  tree_update.root_id = 1;
+  tree_update.nodes.resize(4);
+  tree_update.nodes[0].id = 1;
+  tree_update.nodes[0].role = ax::mojom::Role::kList;
+  tree_update.nodes[0].child_ids = {2, 3, 4};
+  tree_update.nodes[1].id = 2;
+  tree_update.nodes[1].role = ax::mojom::Role::kListItem;
+  tree_update.nodes[2].id = 3;
+  tree_update.nodes[2].role = ax::mojom::Role::kListItem;
+  tree_update.nodes[3].id = 4;
+  tree_update.nodes[3].role = ax::mojom::Role::kListItem;
+  AXTree tree(tree_update);
+
+  AXNode* item1 = tree.GetFromId(2);
+  EXPECT_EQ(item1->PosInSet(), 1);
+  EXPECT_EQ(item1->SetSize(), 3);
+  AXNode* item2 = tree.GetFromId(3);
+  EXPECT_EQ(item2->PosInSet(), 2);
+  EXPECT_EQ(item2->SetSize(), 3);
+  AXNode* item3 = tree.GetFromId(4);
+  EXPECT_EQ(item3->PosInSet(), 3);
+  EXPECT_EQ(item3->SetSize(), 3);
+}
+
+// A test for PosInSet and SetSize on a list containing various roles.
+TEST(AXTreeTest, GetPosInSetSetSizeDiverseList) {
+  AXTreeUpdate tree_update;
+  tree_update.root_id = 1;
+  tree_update.nodes.resize(9);
+  tree_update.nodes[0].id = 1;
+  tree_update.nodes[0].role = ax::mojom::Role::kList;
+  tree_update.nodes[0].child_ids = {2, 3, 4, 5, 6, 7, 8, 9};
+  tree_update.nodes[1].id = 2;
+  tree_update.nodes[1].role = ax::mojom::Role::kListItem;
+  tree_update.nodes[2].id = 3;
+  tree_update.nodes[2].role = ax::mojom::Role::kListItem;
+  tree_update.nodes[3].id = 4;
+  tree_update.nodes[3].role = ax::mojom::Role::kMenuItem;
+  tree_update.nodes[4].id = 5;
+  tree_update.nodes[4].role = ax::mojom::Role::kMenuItem;
+  tree_update.nodes[5].id = 6;
+  tree_update.nodes[5].role = ax::mojom::Role::kArticle;
+  tree_update.nodes[6].id = 7;
+  tree_update.nodes[6].role = ax::mojom::Role::kArticle;
+  tree_update.nodes[7].id = 8;
+  tree_update.nodes[7].role = ax::mojom::Role::kListItem;
+  tree_update.nodes[8].id = 9;
+  tree_update.nodes[8].role = ax::mojom::Role::kImage;
+  AXTree tree(tree_update);
+
+  AXNode* listitem1 = tree.GetFromId(2);
+  EXPECT_EQ(listitem1->PosInSet(), 1);
+  EXPECT_EQ(listitem1->SetSize(), 3);
+  AXNode* listitem2 = tree.GetFromId(3);
+  EXPECT_EQ(listitem2->PosInSet(), 2);
+  EXPECT_EQ(listitem2->SetSize(), 3);
+  AXNode* menuitem1 = tree.GetFromId(4);
+  EXPECT_EQ(menuitem1->PosInSet(), 1);
+  EXPECT_EQ(menuitem1->SetSize(), 2);
+  AXNode* menuitem2 = tree.GetFromId(5);
+  EXPECT_EQ(menuitem2->PosInSet(), 2);
+  EXPECT_EQ(menuitem2->SetSize(), 2);
+  AXNode* article1 = tree.GetFromId(6);
+  EXPECT_EQ(article1->PosInSet(), 1);
+  EXPECT_EQ(article1->SetSize(), 2);
+  AXNode* article2 = tree.GetFromId(7);
+  EXPECT_EQ(article2->PosInSet(), 2);
+  EXPECT_EQ(article2->SetSize(), 2);
+  AXNode* listitem3 = tree.GetFromId(8);
+  EXPECT_EQ(listitem3->PosInSet(), 3);
+  EXPECT_EQ(listitem3->SetSize(), 3);
+  AXNode* image1 = tree.GetFromId(9);
+  EXPECT_EQ(image1->PosInSet(), 0);
+  EXPECT_EQ(image1->SetSize(), 0);
+}
+
 }  // namespace ui