Adds fuchsia node roles to accessibility bridge updates. (flutter#20385)

Author: abrush21

lib/ui/semantics.dart

@@ -300,8 +300,12 @@ class SemanticsFlag {
   static const int _kIsReadOnlyIndex = 1 << 20;
   static const int _kIsFocusableIndex = 1 << 21;
   static const int _kIsLinkIndex = 1 << 22;
+  static const int _kIsSliderIndex = 1 << 23;
   // READ THIS: if you add a flag here, you MUST update the numSemanticsFlags
-  // value in testing/dart/semantics_test.dart, or tests will fail.
+  // value in testing/dart/semantics_test.dart, or tests will fail. Also,
+  // please update the Flag enum in
+  // flutter/shell/platform/android/io/flutter/view/AccessibilityBridge.java,
+  // and the SemanticsFlag class in lib/web_ui/lib/src/ui/semantics.dart.
 
   const SemanticsFlag._(this.index) : assert(index != null); // ignore: unnecessary_null_comparison
 
@@ -355,6 +359,9 @@ class SemanticsFlag {
   /// affordances.
   static const SemanticsFlag isTextField = SemanticsFlag._(_kIsTextFieldIndex);
 
+  /// Whether the semantic node represents a slider.
+  static const SemanticsFlag isSlider = SemanticsFlag._(_kIsSliderIndex);
+
   /// Whether the semantic node is read only.
   ///
   /// Only applicable when [isTextField] is true.
@@ -551,7 +558,8 @@ class SemanticsFlag {
     _kIsReadOnlyIndex: isReadOnly,
     _kIsFocusableIndex: isFocusable,
     _kIsLinkIndex: isLink,
-  };
+    _kIsSliderIndex: isSlider,
+};
 
   @override
   String toString() {
@@ -602,6 +610,8 @@ class SemanticsFlag {
         return 'SemanticsFlag.isFocusable';
       case _kIsLinkIndex:
         return 'SemanticsFlag.isLink';
+      case _kIsSliderIndex:
+        return 'SemanticsFlag.isSlider';
     }
     assert(false, 'Unhandled index: $index');
     return '';

lib/ui/semantics/semantics_node.h

@@ -79,6 +79,7 @@ enum class SemanticsFlags : int32_t {
   kIsReadOnly = 1 << 20,
   kIsFocusable = 1 << 21,
   kIsLink = 1 << 22,
+  kIsSlider = 1 << 23,
 };
 
 const int kScrollableSemanticsFlags =

lib/web_ui/lib/src/ui/semantics.dart

@@ -156,6 +156,7 @@ class SemanticsFlag {
   static const int _kIsReadOnlyIndex = 1 << 20;
   static const int _kIsFocusableIndex = 1 << 21;
   static const int _kIsLinkIndex = 1 << 22;
+  static const int _kIsSliderIndex = 1 << 23;
 
   const SemanticsFlag._(this.index) : assert(index != null); // ignore: unnecessary_null_comparison
   final int index;
@@ -182,12 +183,14 @@ class SemanticsFlag {
   static const SemanticsFlag isToggled = SemanticsFlag._(_kIsToggledIndex);
   static const SemanticsFlag hasImplicitScrolling = SemanticsFlag._(_kHasImplicitScrollingIndex);
   static const SemanticsFlag isMultiline = SemanticsFlag._(_kIsMultilineIndex);
+  static const SemanticsFlag isSlider = SemanticsFlag._(_kIsSliderIndex);
   static const Map<int, SemanticsFlag> values = <int, SemanticsFlag>{
     _kHasCheckedStateIndex: hasCheckedState,
     _kIsCheckedIndex: isChecked,
     _kIsSelectedIndex: isSelected,
     _kIsButtonIndex: isButton,
     _kIsLinkIndex: isLink,
+    _kIsSliderIndex: isSlider,
     _kIsTextFieldIndex: isTextField,
     _kIsFocusableIndex: isFocusable,
     _kIsFocusedIndex: isFocused,

shell/platform/fuchsia/flutter/accessibility_bridge.cc

@@ -115,6 +115,31 @@ fuchsia::accessibility::semantics::States AccessibilityBridge::GetNodeStates(
   return states;
 }
 
+fuchsia::accessibility::semantics::Role AccessibilityBridge::GetNodeRole(
+    const flutter::SemanticsNode& node) const {
+  if (node.HasFlag(flutter::SemanticsFlags::kIsButton)) {
+    return fuchsia::accessibility::semantics::Role::BUTTON;
+  }
+
+  if (node.HasFlag(flutter::SemanticsFlags::kIsHeader)) {
+    return fuchsia::accessibility::semantics::Role::HEADER;
+  }
+
+  if (node.HasFlag(flutter::SemanticsFlags::kIsImage)) {
+    return fuchsia::accessibility::semantics::Role::IMAGE;
+  }
+
+  if (node.HasFlag(flutter::SemanticsFlags::kIsTextField)) {
+    return fuchsia::accessibility::semantics::Role::TEXT_FIELD;
+  }
+
+  if (node.HasFlag(flutter::SemanticsFlags::kIsSlider)) {
+    return fuchsia::accessibility::semantics::Role::SLIDER;
+  }
+
+  return fuchsia::accessibility::semantics::Role::UNKNOWN;
+}
+
 std::unordered_set<int32_t> AccessibilityBridge::GetDescendants(
     int32_t node_id) const {
   std::unordered_set<int32_t> descendents;
@@ -227,6 +252,7 @@ void AccessibilityBridge::AddSemanticsNodeUpdate(
         .set_transform(GetNodeTransform(flutter_node))
         .set_attributes(GetNodeAttributes(flutter_node, &this_node_size))
         .set_states(GetNodeStates(flutter_node, &this_node_size))
+        .set_role(GetNodeRole(flutter_node))
         .set_child_ids(child_ids);
     this_node_size +=
         kNodeIdSize * flutter_node.childrenInTraversalOrder.size();

shell/platform/fuchsia/flutter/accessibility_bridge.h

@@ -145,6 +145,11 @@ class AccessibilityBridge
       const flutter::SemanticsNode& node,
       size_t* additional_size) const;
 
+  // Derives the role for a Fuchsia semantics node from a Flutter semantics
+  // node.
+  fuchsia::accessibility::semantics::Role GetNodeRole(
+      const flutter::SemanticsNode& node) const;
+
   // Gets the set of reachable descendants from the given node id.
   std::unordered_set<int32_t> GetDescendants(int32_t node_id) const;
 

shell/platform/fuchsia/flutter/accessibility_bridge_unittest.cc

@@ -19,6 +19,20 @@
 
 namespace flutter_runner_test {
 
+namespace {
+
+void ExpectNodeHasRole(
+    const fuchsia::accessibility::semantics::Node& node,
+    const std::unordered_map<uint32_t, fuchsia::accessibility::semantics::Role>
+        roles_by_node_id) {
+  ASSERT_TRUE(node.has_node_id());
+  ASSERT_NE(roles_by_node_id.find(node.node_id()), roles_by_node_id.end());
+  EXPECT_TRUE(node.has_role());
+  EXPECT_EQ(node.role(), roles_by_node_id.at(node.node_id()));
+}
+
+}  // namespace
+
 class AccessibilityBridgeTestDelegate
     : public flutter_runner::AccessibilityBridge::Delegate {
  public:
@@ -89,6 +103,67 @@ TEST_F(AccessibilityBridgeTest, EnableDisable) {
   EXPECT_TRUE(accessibility_delegate_.enabled());
 }
 
+TEST_F(AccessibilityBridgeTest, UpdatesNodeRoles) {
+  flutter::SemanticsNodeUpdates updates;
+
+  flutter::SemanticsNode node0;
+  node0.id = 0;
+  node0.flags |= static_cast<int>(flutter::SemanticsFlags::kIsButton);
+  node0.childrenInTraversalOrder = {1, 2, 3, 4};
+  node0.childrenInHitTestOrder = {1, 2, 3, 4};
+  updates.emplace(0, node0);
+
+  flutter::SemanticsNode node1;
+  node1.id = 1;
+  node1.flags |= static_cast<int>(flutter::SemanticsFlags::kIsHeader);
+  node1.childrenInTraversalOrder = {};
+  node1.childrenInHitTestOrder = {};
+  updates.emplace(1, node1);
+
+  flutter::SemanticsNode node2;
+  node2.id = 2;
+  node2.flags |= static_cast<int>(flutter::SemanticsFlags::kIsImage);
+  node2.childrenInTraversalOrder = {};
+  node2.childrenInHitTestOrder = {};
+  updates.emplace(2, node2);
+
+  flutter::SemanticsNode node3;
+  node3.id = 3;
+  node3.flags |= static_cast<int>(flutter::SemanticsFlags::kIsTextField);
+  node3.childrenInTraversalOrder = {};
+  node3.childrenInHitTestOrder = {};
+  updates.emplace(3, node3);
+
+  flutter::SemanticsNode node4;
+  node4.childrenInTraversalOrder = {};
+  node4.childrenInHitTestOrder = {};
+  node4.id = 4;
+  node4.flags |= static_cast<int>(flutter::SemanticsFlags::kIsSlider);
+  updates.emplace(4, node4);
+
+  accessibility_bridge_->AddSemanticsNodeUpdate(std::move(updates));
+  RunLoopUntilIdle();
+
+  std::unordered_map<uint32_t, fuchsia::accessibility::semantics::Role>
+      roles_by_node_id = {
+          {0u, fuchsia::accessibility::semantics::Role::BUTTON},
+          {1u, fuchsia::accessibility::semantics::Role::HEADER},
+          {2u, fuchsia::accessibility::semantics::Role::IMAGE},
+          {3u, fuchsia::accessibility::semantics::Role::TEXT_FIELD},
+          {4u, fuchsia::accessibility::semantics::Role::SLIDER}};
+
+  EXPECT_EQ(0, semantics_manager_.DeleteCount());
+  EXPECT_EQ(1, semantics_manager_.UpdateCount());
+  EXPECT_EQ(1, semantics_manager_.CommitCount());
+  EXPECT_EQ(5U, semantics_manager_.LastUpdatedNodes().size());
+  for (const auto& node : semantics_manager_.LastUpdatedNodes()) {
+    ExpectNodeHasRole(node, roles_by_node_id);
+  }
+
+  EXPECT_FALSE(semantics_manager_.DeleteOverflowed());
+  EXPECT_FALSE(semantics_manager_.UpdateOverflowed());
+}
+
 TEST_F(AccessibilityBridgeTest, DeletesChildrenTransitively) {
   // Test that when a node is deleted, so are its transitive children.
   flutter::SemanticsNode node2;

testing/dart/semantics_test.dart

@@ -9,7 +9,7 @@ import 'package:test/test.dart' hide TypeMatcher, isInstanceOf;
 /// Verifies Semantics flags and actions.
 void main() {
   // This must match the number of flags in lib/ui/semantics.dart
-  const int numSemanticsFlags = 23;
+  const int numSemanticsFlags = 24;
   test('SemanticsFlag.values refers to all flags.', () async {
     expect(SemanticsFlag.values.length, equals(numSemanticsFlags));
     for (int index = 0; index < numSemanticsFlags; ++index) {