Add 'header' SemanticsFlag to AppBar, NavBar (#18289)

packages/flutter/lib/src/cupertino/nav_bar.dart

@@ -147,7 +147,7 @@ class CupertinoNavigationBar extends StatelessWidget implements ObstructingPrefe
       child: new _CupertinoPersistentNavigationBar(
         leading: leading,
         automaticallyImplyLeading: automaticallyImplyLeading,
-        middle: middle,
+        middle: new Semantics(child: middle, header: true),
         trailing: trailing,
         actionsForegroundColor: actionsForegroundColor,
       ),
@@ -491,7 +491,7 @@ class _CupertinoLargeTitleNavigationBarSliverDelegate
         new _CupertinoPersistentNavigationBar(
       leading: leading,
       automaticallyImplyLeading: automaticallyImplyLeading,
-      middle: middle ?? title,
+      middle: new Semantics(child: middle ?? title, header: true),
       trailing: trailing,
       // If middle widget exists, always show it. Otherwise, show title
       // when collapsed.
@@ -533,7 +533,10 @@ class _CupertinoLargeTitleNavigationBarSliverDelegate
                       child: new SafeArea(
                         top: false,
                         bottom: false,
-                        child: title,
+                        child: new Semantics(
+                          header: true,
+                          child: title,
+                        ),
                       ),
                     ),
                   ),

packages/flutter/lib/src/material/app_bar.dart

@@ -393,20 +393,24 @@ class _AppBarState extends State<AppBar> {
 
     Widget title = widget.title;
     if (title != null) {
+      bool namesRoute;
       switch (defaultTargetPlatform) {
         case TargetPlatform.android:
         case TargetPlatform.fuchsia:
-           title = new Semantics(namesRoute: true, child: title);
+           namesRoute = true;
            break;
         case TargetPlatform.iOS:
           break;
       }
-
       title = new DefaultTextStyle(
         style: centerStyle,
         softWrap: false,
         overflow: TextOverflow.ellipsis,
-        child: title,
+        child: new Semantics(
+          namesRoute: namesRoute,
+          child: title,
+          header: true,
+        ),
       );
     }
 
@@ -626,7 +630,9 @@ class _SliverAppBarDelegate extends SliverPersistentHeaderDelegate {
         automaticallyImplyLeading: automaticallyImplyLeading,
         title: title,
         actions: actions,
-        flexibleSpace: flexibleSpace,
+        flexibleSpace: (title == null && flexibleSpace != null)
+          ? new Semantics(child: flexibleSpace, header: true)
+          : flexibleSpace,
         bottom: bottom,
         elevation: forceElevated || overlapsContent || (pinned && shrinkOffset > maxExtent - minExtent) ? elevation ?? 4.0 : 0.0,
         backgroundColor: backgroundColor,

packages/flutter/test/cupertino/nav_bar_test.dart

@@ -8,6 +8,8 @@ import 'package:flutter/cupertino.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart' hide TypeMatcher;
 
+import '../widgets/semantics_tester.dart';
+
 int count = 0;
 
 void main() {
@@ -567,6 +569,68 @@ void main() {
     expect(decoration.border, isNull);
   });
 
+  testWidgets('CupertinoSliverNavigationBar has semantics', (WidgetTester tester) async {
+    final SemanticsTester semantics = new SemanticsTester(tester);
+
+    await tester.pumpWidget(new WidgetsApp(
+        color: const Color(0xFFFFFFFF),
+        onGenerateRoute: (RouteSettings settings) {
+          return new CupertinoPageRoute<void>(
+            settings: settings,
+            builder: (BuildContext context) {
+              return new CupertinoPageScaffold(
+                child: new CustomScrollView(
+                  slivers: const <Widget>[
+                    const CupertinoSliverNavigationBar(
+                      largeTitle: const Text('Large Title'),
+                      border: null,
+                    ),
+                  ],
+                ),
+              );
+            },
+          );
+        }
+    ));
+
+    expect(semantics.nodesWith(
+      label: 'Large Title',
+      flags: <SemanticsFlag>[SemanticsFlag.isHeader],
+      textDirection: TextDirection.ltr,
+    ), hasLength(1));
+
+    semantics.dispose();
+  });
+
+  testWidgets('CupertinoNavigationBar has semantics', (WidgetTester tester) async {
+    final SemanticsTester semantics = new SemanticsTester(tester);
+
+    await tester.pumpWidget(new WidgetsApp(
+        color: const Color(0xFFFFFFFF),
+        onGenerateRoute: (RouteSettings settings) {
+          return new CupertinoPageRoute<void>(
+            settings: settings,
+            builder: (BuildContext context) {
+              return new CupertinoPageScaffold(
+                navigationBar: const CupertinoNavigationBar(
+                  middle: const Text('Fixed Title'),
+                ),
+                child: new Container(),
+              );
+            },
+          );
+        }
+    ));
+
+    expect(semantics.nodesWith(
+      label: 'Fixed Title',
+      flags: <SemanticsFlag>[SemanticsFlag.isHeader],
+      textDirection: TextDirection.ltr,
+    ), hasLength(1));
+
+    semantics.dispose();
+  });
+
   testWidgets(
       'Border can be overridden in sliver nav bar',
       (WidgetTester tester) async {

packages/flutter/test/material/app_bar_test.dart

@@ -1214,7 +1214,10 @@ void main() {
                         textDirection: TextDirection.ltr,
                       ),
                       new TestSemantics(
-                        flags: <SemanticsFlag>[SemanticsFlag.namesRoute],
+                        flags: <SemanticsFlag>[
+                          SemanticsFlag.namesRoute,
+                          SemanticsFlag.isHeader,
+                        ],
                         label: 'Title',
                         textDirection: TextDirection.ltr,
                       ),
@@ -1297,7 +1300,10 @@ void main() {
                             textDirection: TextDirection.rtl,
                           ),
                           new TestSemantics(
-                            flags: <SemanticsFlag>[SemanticsFlag.namesRoute],
+                            flags: <SemanticsFlag>[
+                              SemanticsFlag.namesRoute,
+                              SemanticsFlag.isHeader,
+                            ],
                             label: 'Title',
                             textDirection: TextDirection.rtl,
                           ),

packages/flutter/test/widgets/navigator_test.dart

@@ -789,7 +789,10 @@ void main() {
     ));
     expect(semantics, includesNodeWith(
       label: 'Page 1',
-      flags: <SemanticsFlag>[SemanticsFlag.namesRoute],
+      flags: <SemanticsFlag>[
+        SemanticsFlag.namesRoute,
+        SemanticsFlag.isHeader,
+      ],
     ));
 
     await tester.tap(find.text('1')); // pushNamed('/A')
@@ -801,7 +804,10 @@ void main() {
     ));
     expect(semantics, includesNodeWith(
       label: 'Page 2',
-      flags: <SemanticsFlag>[SemanticsFlag.namesRoute],
+      flags: <SemanticsFlag>[
+        SemanticsFlag.namesRoute,
+        SemanticsFlag.isHeader,
+      ],
     ));
 
     await tester.tap(find.text('2')); // pushNamed('/B/C')
@@ -809,11 +815,16 @@ void main() {
     await tester.pump(const Duration(seconds: 1));
 
     expect(semantics, includesNodeWith(
-      flags: <SemanticsFlag>[SemanticsFlag.scopesRoute],
+      flags: <SemanticsFlag>[
+        SemanticsFlag.scopesRoute,
+      ],
     ));
     expect(semantics, includesNodeWith(
       label: 'Page 3',
-      flags: <SemanticsFlag>[SemanticsFlag.namesRoute],
+      flags: <SemanticsFlag>[
+        SemanticsFlag.namesRoute,
+        SemanticsFlag.isHeader,
+      ],
     ));
 
 

packages/flutter/test/widgets/sliver_semantics_test.dart

@@ -79,7 +79,10 @@ void _tests() {
                         children: <TestSemantics>[
                           new TestSemantics(
                             id: 8,
-                            flags: <SemanticsFlag>[SemanticsFlag.namesRoute],
+                            flags: <SemanticsFlag>[
+                              SemanticsFlag.namesRoute,
+                              SemanticsFlag.isHeader,
+                            ],
                             label: 'Semantics Test with Slivers',
                             textDirection: TextDirection.ltr,
                           ),
@@ -140,7 +143,10 @@ void _tests() {
                     children: <TestSemantics>[
                       new TestSemantics(
                         id: 8,
-                        flags: <SemanticsFlag>[SemanticsFlag.namesRoute],
+                        flags: <SemanticsFlag>[
+                          SemanticsFlag.namesRoute,
+                          SemanticsFlag.isHeader,
+                        ],
                         label: 'Semantics Test with Slivers',
                         textDirection: TextDirection.ltr,
                       ),
@@ -219,7 +225,10 @@ void _tests() {
                         children: <TestSemantics>[
                           new TestSemantics(
                             id: 8,
-                            flags: <SemanticsFlag>[SemanticsFlag.namesRoute],
+                            flags: <SemanticsFlag>[
+                              SemanticsFlag.namesRoute,
+                              SemanticsFlag.isHeader,
+                            ],
                             label: 'Semantics Test with Slivers',
                             textDirection: TextDirection.ltr,
                           ),
@@ -458,7 +467,10 @@ void _tests() {
                     tags: <SemanticsTag>[RenderViewport.excludeFromScrolling],
                     children: <TestSemantics>[
                       new TestSemantics(
-                        flags: <SemanticsFlag>[SemanticsFlag.namesRoute],
+                        flags: <SemanticsFlag>[
+                          SemanticsFlag.namesRoute,
+                          SemanticsFlag.isHeader,
+                        ],
                         label: 'AppBar',
                         textDirection: TextDirection.ltr,
                       ),
@@ -557,7 +569,10 @@ void _tests() {
                     tags: <SemanticsTag>[RenderViewport.excludeFromScrolling],
                     children: <TestSemantics>[
                       new TestSemantics(
-                        flags: <SemanticsFlag>[SemanticsFlag.namesRoute],
+                        flags: <SemanticsFlag>[
+                          SemanticsFlag.namesRoute,
+                          SemanticsFlag.isHeader,
+                        ],
                         label: 'AppBar',
                         textDirection: TextDirection.ltr,
                       ),
@@ -693,7 +708,10 @@ void _tests() {
                     tags: <SemanticsTag>[RenderViewport.excludeFromScrolling],
                     children: <TestSemantics>[
                       new TestSemantics(
-                        flags: <SemanticsFlag>[SemanticsFlag.namesRoute],
+                        flags: <SemanticsFlag>[
+                          SemanticsFlag.namesRoute,
+                          SemanticsFlag.isHeader,
+                        ],
                         label: 'AppBar',
                         textDirection: TextDirection.ltr,
                       ),
@@ -791,7 +809,10 @@ void _tests() {
                     tags: <SemanticsTag>[RenderViewport.excludeFromScrolling],
                     children: <TestSemantics>[
                       new TestSemantics(
-                        flags: <SemanticsFlag>[SemanticsFlag.namesRoute],
+                        flags: <SemanticsFlag>[
+                          SemanticsFlag.namesRoute,
+                          SemanticsFlag.isHeader,
+                        ],
                         label: 'AppBar',
                         textDirection: TextDirection.ltr,
                       ),
@@ -883,7 +904,10 @@ void _tests() {
                     tags: <SemanticsTag>[RenderViewport.excludeFromScrolling],
                     children: <TestSemantics>[
                       new TestSemantics(
-                        flags: <SemanticsFlag>[SemanticsFlag.namesRoute],
+                        flags: <SemanticsFlag>[
+                          SemanticsFlag.namesRoute,
+                          SemanticsFlag.isHeader,
+                        ],
                         label: 'Forward app bar',
                         textDirection: TextDirection.ltr,
                       ),
@@ -986,7 +1010,10 @@ void _tests() {
                     tags: <SemanticsTag>[RenderViewport.excludeFromScrolling],
                     children: <TestSemantics>[
                       new TestSemantics(
-                        flags: <SemanticsFlag>[SemanticsFlag.namesRoute],
+                        flags: <SemanticsFlag>[
+                          SemanticsFlag.namesRoute,
+                          SemanticsFlag.isHeader,
+                        ],
                         label: 'Backward app bar',
                         textDirection: TextDirection.ltr,
                       ),