migrate complex layout to null safety (#83894)

dev/benchmarks/complex_layout/lib/main.dart

@@ -14,12 +14,12 @@ void main() {
 enum ScrollMode { complex, tile }
 
 class ComplexLayoutApp extends StatefulWidget {
-  const ComplexLayoutApp({Key key}) : super(key: key);
+  const ComplexLayoutApp({Key? key}) : super(key: key);
 
   @override
   ComplexLayoutAppState createState() => ComplexLayoutAppState();
 
-  static ComplexLayoutAppState of(BuildContext context) => context.findAncestorStateOfType<ComplexLayoutAppState>();
+  static ComplexLayoutAppState? of(BuildContext context) => context.findAncestorStateOfType<ComplexLayoutAppState>();
 }
 
 class ComplexLayoutAppState extends State<ComplexLayoutApp> {
@@ -55,7 +55,7 @@ class ComplexLayoutAppState extends State<ComplexLayoutApp> {
 }
 
 class TileScrollLayout extends StatelessWidget {
-  const TileScrollLayout({ Key key }) : super(key: key);
+  const TileScrollLayout({ Key? key }) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
@@ -81,12 +81,12 @@ class TileScrollLayout extends StatelessWidget {
 }
 
 class ComplexLayout extends StatefulWidget {
-  const ComplexLayout({ Key key }) : super(key: key);
+  const ComplexLayout({ Key? key }) : super(key: key);
 
   @override
   ComplexLayoutState createState() => ComplexLayoutState();
 
-  static ComplexLayoutState of(BuildContext context) => context.findAncestorStateOfType<ComplexLayoutState>();
+  static ComplexLayoutState? of(BuildContext context) => context.findAncestorStateOfType<ComplexLayoutState>();
 }
 
 class ComplexLayoutState extends State<ComplexLayout> {
@@ -129,7 +129,7 @@ class ComplexLayoutState extends State<ComplexLayout> {
 }
 
 class TopBarMenu extends StatelessWidget {
-  const TopBarMenu({Key key}) : super(key: key);
+  const TopBarMenu({Key? key}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
@@ -182,7 +182,7 @@ class TopBarMenu extends StatelessWidget {
 }
 
 class MenuItemWithIcon extends StatelessWidget {
-  const MenuItemWithIcon(this.icon, this.title, this.subtitle, {Key key}) : super(key: key);
+  const MenuItemWithIcon(this.icon, this.title, this.subtitle, {Key? key}) : super(key: key);
 
   final IconData icon;
   final String title;
@@ -204,7 +204,7 @@ class MenuItemWithIcon extends StatelessWidget {
 }
 
 class FancyImageItem extends StatelessWidget {
-  const FancyImageItem(this.index, {Key key}) : super(key: key);
+  const FancyImageItem(this.index, {Key? key}) : super(key: key);
 
   final int index;
 
@@ -228,7 +228,7 @@ class FancyImageItem extends StatelessWidget {
 }
 
 class FancyGalleryItem extends StatelessWidget {
-  const FancyGalleryItem(this.index, {Key key}) : super(key: key);
+  const FancyGalleryItem(this.index, {Key? key}) : super(key: key);
 
   final int index;
   @override
@@ -250,7 +250,7 @@ class FancyGalleryItem extends StatelessWidget {
 }
 
 class InfoBar extends StatelessWidget {
-  const InfoBar({Key key}) : super(key: key);
+  const InfoBar({Key? key}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
@@ -268,7 +268,7 @@ class InfoBar extends StatelessWidget {
 }
 
 class IconBar extends StatelessWidget {
-  const IconBar({Key key}) : super(key: key);
+  const IconBar({Key? key}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
@@ -287,7 +287,7 @@ class IconBar extends StatelessWidget {
 }
 
 class IconWithText extends StatelessWidget {
-  const IconWithText(this.icon, this.title, {Key key}) : super(key: key);
+  const IconWithText(this.icon, this.title, {Key? key}) : super(key: key);
 
   final IconData icon;
   final String title;
@@ -308,7 +308,7 @@ class IconWithText extends StatelessWidget {
 }
 
 class MiniIconWithText extends StatelessWidget {
-  const MiniIconWithText(this.icon, this.title, {Key key}) : super(key: key);
+  const MiniIconWithText(this.icon, this.title, {Key? key}) : super(key: key);
 
   final IconData icon;
   final String title;
@@ -337,7 +337,7 @@ class MiniIconWithText extends StatelessWidget {
 }
 
 class FatDivider extends StatelessWidget {
-  const FatDivider({Key key}) : super(key: key);
+  const FatDivider({Key? key}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
@@ -349,7 +349,7 @@ class FatDivider extends StatelessWidget {
 }
 
 class UserHeader extends StatelessWidget {
-  const UserHeader(this.userName, {Key key}) : super(key: key);
+  const UserHeader(this.userName, {Key? key}) : super(key: key);
 
   final String userName;
 
@@ -384,7 +384,7 @@ class UserHeader extends StatelessWidget {
                 Row(
                   children: <Widget>[
                     Text('Yesterday at 11:55 • ', style: Theme.of(context).textTheme.caption),
-                    Icon(Icons.people, size: 16.0, color: Theme.of(context).textTheme.caption.color),
+                    Icon(Icons.people, size: 16.0, color: Theme.of(context).textTheme.caption!.color),
                   ],
                 ),
               ],
@@ -398,7 +398,7 @@ class UserHeader extends StatelessWidget {
 }
 
 class ItemDescription extends StatelessWidget {
-  const ItemDescription({Key key}) : super(key: key);
+  const ItemDescription({Key? key}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
@@ -410,7 +410,7 @@ class ItemDescription extends StatelessWidget {
 }
 
 class ItemImageBox extends StatelessWidget {
-  const ItemImageBox({Key key}) : super(key: key);
+  const ItemImageBox({Key? key}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
@@ -491,7 +491,7 @@ class ItemImageBox extends StatelessWidget {
 }
 
 class ItemGalleryBox extends StatelessWidget {
-  const ItemGalleryBox(this.index, {Key key}) : super(key: key);
+  const ItemGalleryBox(this.index, {Key? key}) : super(key: key);
 
   final int index;
 
@@ -521,7 +521,7 @@ class ItemGalleryBox extends StatelessWidget {
                               child: Container(
                                 color: Theme.of(context).primaryColor,
                                 child: Center(
-                                  child: Text(tabName, style: Theme.of(context).textTheme.headline5.copyWith(color: Colors.white)),
+                                  child: Text(tabName, style: Theme.of(context).textTheme.headline5!.copyWith(color: Colors.white)),
                                 ),
                               ),
                             ),
@@ -560,7 +560,7 @@ class ItemGalleryBox extends StatelessWidget {
 }
 
 class BottomBar extends StatelessWidget {
-  const BottomBar({Key key}) : super(key: key);
+  const BottomBar({Key? key}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {
@@ -588,7 +588,7 @@ class BottomBar extends StatelessWidget {
 }
 
 class BottomBarButton extends StatelessWidget {
-  const BottomBarButton(this.icon, this.title, {Key key}) : super(key: key);
+  const BottomBarButton(this.icon, this.title, {Key? key}) : super(key: key);
 
   final IconData icon;
   final String title;
@@ -611,19 +611,19 @@ class BottomBarButton extends StatelessWidget {
 }
 
 class GalleryDrawer extends StatelessWidget {
-  const GalleryDrawer({ Key key }) : super(key: key);
+  const GalleryDrawer({ Key? key }) : super(key: key);
 
   void _changeTheme(BuildContext context, bool value) {
-    ComplexLayoutApp.of(context).lightTheme = value;
+    ComplexLayoutApp.of(context)?.lightTheme = value;
   }
 
   void _changeScrollMode(BuildContext context, ScrollMode mode) {
-    ComplexLayoutApp.of(context).scrollMode = mode;
+    ComplexLayoutApp.of(context)?.scrollMode = mode;
   }
 
   @override
   Widget build(BuildContext context) {
-    final ScrollMode currentMode = ComplexLayoutApp.of(context).scrollMode;
+    final ScrollMode currentMode = ComplexLayoutApp.of(context)!.scrollMode;
     return Drawer(
       // Note: for real apps, see the Gallery material Drawer demo. More
       // typically, a drawer would have a fixed header with a scrolling body
@@ -646,22 +646,22 @@ class GalleryDrawer extends StatelessWidget {
             leading: const Icon(Icons.brightness_5),
             title: const Text('Light'),
             onTap: () { _changeTheme(context, true); },
-            selected: ComplexLayoutApp.of(context).lightTheme,
+            selected: ComplexLayoutApp.of(context)!.lightTheme,
             trailing: Radio<bool>(
               value: true,
-              groupValue: ComplexLayoutApp.of(context).lightTheme,
-              onChanged: (bool value) { _changeTheme(context, value); },
+              groupValue: ComplexLayoutApp.of(context)!.lightTheme,
+              onChanged: (bool? value) { _changeTheme(context, value!); },
             ),
           ),
           ListTile(
             leading: const Icon(Icons.brightness_7),
             title: const Text('Dark'),
             onTap: () { _changeTheme(context, false); },
-            selected: !ComplexLayoutApp.of(context).lightTheme,
+            selected: !ComplexLayoutApp.of(context)!.lightTheme,
             trailing: Radio<bool>(
               value: false,
-              groupValue: ComplexLayoutApp.of(context).lightTheme,
-              onChanged: (bool value) { _changeTheme(context, value); },
+              groupValue: ComplexLayoutApp.of(context)!.lightTheme,
+              onChanged: (bool? value) { _changeTheme(context, value!); },
             ),
           ),
           const Divider(),
@@ -669,10 +669,10 @@ class GalleryDrawer extends StatelessWidget {
             leading: const Icon(Icons.hourglass_empty),
             title: const Text('Animate Slowly'),
             selected: timeDilation != 1.0,
-            onTap: () { ComplexLayoutApp.of(context).toggleAnimationSpeed(); },
+            onTap: () { ComplexLayoutApp.of(context)!.toggleAnimationSpeed(); },
             trailing: Checkbox(
               value: timeDilation != 1.0,
-              onChanged: (bool value) { ComplexLayoutApp.of(context).toggleAnimationSpeed(); },
+              onChanged: (bool? value) { ComplexLayoutApp.of(context)!.toggleAnimationSpeed(); },
             ),
           ),
         ],
@@ -682,7 +682,7 @@ class GalleryDrawer extends StatelessWidget {
 }
 
 class FancyDrawerHeader extends StatelessWidget {
-  const FancyDrawerHeader({Key key}) : super(key: key);
+  const FancyDrawerHeader({Key? key}) : super(key: key);
 
   @override
   Widget build(BuildContext context) {

dev/benchmarks/complex_layout/pubspec.yaml

@@ -2,7 +2,7 @@ name: complex_layout
 description: A benchmark of a relatively complex layout.
 
 environment:
-  sdk: ">=2.2.2 <3.0.0"
+  sdk: ">=2.12.0 <3.0.0"
 
 dependencies:
   flutter:

dev/benchmarks/complex_layout/test/measure_scroll_smoothness.dart

@@ -66,7 +66,7 @@ class ResampleFlagVariant extends TestVariant<TestScenario> {
   @override
   final Set<TestScenario> values = Set<TestScenario>.from(TestScenario.values);
 
-  TestScenario currentValue;
+  late TestScenario currentValue;
   bool get resample {
     switch(currentValue) {
       case TestScenario.resampleOn90Hz:
@@ -76,7 +76,6 @@ class ResampleFlagVariant extends TestVariant<TestScenario> {
       case TestScenario.resampleOff59Hz:
         return false;
     }
-    throw ArgumentError;
   }
   double get frequency {
     switch(currentValue) {
@@ -87,10 +86,9 @@ class ResampleFlagVariant extends TestVariant<TestScenario> {
       case TestScenario.resampleOff59Hz:
         return 59.0;
     }
-    throw ArgumentError;
   }
 
-  Map<String, dynamic> result;
+  Map<String, dynamic>? result;
 
   @override
   String describeValue(TestScenario value) {
@@ -104,7 +102,6 @@ class ResampleFlagVariant extends TestVariant<TestScenario> {
       case TestScenario.resampleOff59Hz:
         return 'resample off with 59Hz input';
     }
-    throw ArgumentError;
   }
 
   @override
@@ -118,7 +115,7 @@ class ResampleFlagVariant extends TestVariant<TestScenario> {
   @override
   Future<void> tearDown(TestScenario value, bool memento) async {
     binding.resamplingEnabled = memento;
-    binding.reportData[describeValue(value)] = result;
+    binding.reportData![describeValue(value)] = result;
   }
 }
 
@@ -134,16 +131,16 @@ Future<void> main() async {
     await tester.pumpAndSettle();
     final Finder scrollerFinder = find.byKey(const ValueKey<String>('complex-scroll'));
     final ListView scroller = tester.widget<ListView>(scrollerFinder);
-    final ScrollController controller = scroller.controller;
+    final ScrollController? controller = scroller.controller;
     final List<int> frameTimestamp = <int>[];
     final List<double> scrollOffset = <double>[];
     final List<Duration> delays = <Duration>[];
     binding.addPersistentFrameCallback((Duration timeStamp) {
-      if (controller.hasClients) {
+      if (controller?.hasClients == true) {
         // This if is necessary because by the end of the test the widget tree
         // is destroyed.
         frameTimestamp.add(timeStamp.inMicroseconds);
-        scrollOffset.add(controller.offset);
+        scrollOffset.add(controller!.offset);
       }
     });
 

dev/benchmarks/complex_layout/test_driver/measure_scroll_smoothness_test.dart

@@ -8,7 +8,7 @@ import 'package:integration_test/integration_test_driver.dart' as driver;
 
 Future<void> main() => driver.integrationDriver(
   timeout: const Duration(minutes: 5),
-  responseDataCallback: (Map<String, dynamic> data) async {
+  responseDataCallback: (Map<String, dynamic>? data) async {
     await driver.writeResponseData(
       data,
       testOutputFilename: 'scroll_smoothness_test',

dev/benchmarks/complex_layout/test_driver/scroll_perf_test.dart

@@ -9,7 +9,7 @@ import 'package:test/test.dart' hide TypeMatcher, isInstanceOf;
 
 void main() {
   group('scrolling performance test', () {
-    FlutterDriver driver;
+    late FlutterDriver driver;
 
     setUpAll(() async {
       driver = await FlutterDriver.connect();

dev/benchmarks/complex_layout/test_driver/semantics_perf_test.dart

@@ -12,7 +12,7 @@ import 'package:test/test.dart' hide TypeMatcher, isInstanceOf;
 
 void main() {
   group('semantics performance test', () {
-    FlutterDriver driver;
+    late FlutterDriver driver;
 
     setUpAll(() async {
       driver = await FlutterDriver.connect(printCommunication: true);
@@ -33,10 +33,10 @@ void main() {
         expect(await driver.setSemantics(true), isTrue);
       });
 
-      final Iterable<TimelineEvent> semanticsEvents = timeline.events.where((TimelineEvent event) => event.name == 'Semantics');
-      if (semanticsEvents.length != 2)
-        fail('Expected exactly two semantics events, got ${semanticsEvents.length}');
-      final Duration semanticsTreeCreation = Duration(microseconds: semanticsEvents.last.timestampMicros - semanticsEvents.first.timestampMicros);
+      final Iterable<TimelineEvent>? semanticsEvents = timeline.events?.where((TimelineEvent event) => event.name == 'Semantics');
+      if (semanticsEvents?.length != 2)
+        fail('Expected exactly two semantics events, got ${semanticsEvents?.length}');
+      final Duration semanticsTreeCreation = Duration(microseconds: semanticsEvents!.last.timestampMicros! - semanticsEvents.first.timestampMicros!);
 
       final String jsonEncoded = json.encode(<String, dynamic>{'initialSemanticsTreeCreation': semanticsTreeCreation.inMilliseconds});
       File(p.join(testOutputsDirectory, 'complex_layout_semantics_perf.json')).writeAsStringSync(jsonEncoded);

dev/benchmarks/complex_layout/test_memory/scroll_perf.dart

@@ -32,7 +32,7 @@ Future<void> main() async {
       child: ComplexLayoutApp(),
     ),
   ));
-  await SchedulerBinding.instance.endOfFrame;
+  await SchedulerBinding.instance?.endOfFrame;
 
   /// Wait 50ms to allow the raster thread to actually put up the frame. (The
   /// endOfFrame future ends when we send the data to the engine, before
@@ -50,9 +50,9 @@ Future<void> main() async {
       child: ComplexLayoutApp(),
     ),
   ));
-  await SchedulerBinding.instance.endOfFrame;
+  await SchedulerBinding.instance?.endOfFrame;
 
-  final WidgetController controller = LiveWidgetController(WidgetsBinding.instance);
+  final WidgetController controller = LiveWidgetController(WidgetsBinding.instance!);
 
   // Scroll down
   for (int iteration = 0; iteration < maxIterations; iteration += 1) {