Migrate all of examples/layers to sound null safety (#68744)

dev/bots/test.dart

@@ -604,7 +604,7 @@ Future<void> _runFrameworkTests() async {
     await _runFlutterTest(path.join(flutterRoot, 'dev', 'manual_tests'), tableData: bigqueryApi?.tabledata);
     await _runFlutterTest(path.join(flutterRoot, 'dev', 'tools', 'vitool'), tableData: bigqueryApi?.tabledata);
     await _runFlutterTest(path.join(flutterRoot, 'examples', 'hello_world'), tableData: bigqueryApi?.tabledata);
-    await _runFlutterTest(path.join(flutterRoot, 'examples', 'layers'), tableData: bigqueryApi?.tabledata, options: mixedModeNullSafetyOptions);
+    await _runFlutterTest(path.join(flutterRoot, 'examples', 'layers'), tableData: bigqueryApi?.tabledata, options: soundNullSafetyOptions);
     await _runFlutterTest(path.join(flutterRoot, 'dev', 'benchmarks', 'test_apps', 'stocks'), tableData: bigqueryApi?.tabledata);
     await _runFlutterTest(path.join(flutterRoot, 'packages', 'flutter_driver'), tableData: bigqueryApi?.tabledata, tests: <String>[path.join('test', 'src', 'real_tests')]);
     await _runFlutterTest(path.join(flutterRoot, 'packages', 'flutter_goldens'), tableData: bigqueryApi?.tabledata);

examples/layers/pubspec.yaml

@@ -2,7 +2,7 @@ name: flutter_examples_layers
 
 environment:
   # The pub client defaults to an <2.0.0 sdk constraint which we need to explicitly overwrite.
-  sdk: ">=2.0.0-dev.68.0 <3.0.0"
+  sdk: ">=2.10.0-0.0.dev <3.0.0"
 
 dependencies:
   flutter:

examples/layers/raw/text.dart

@@ -9,7 +9,7 @@ import 'dart:typed_data';
 import 'dart:ui' as ui;
 
 // A paragraph represents a rectangular region that contains some text.
-ui.Paragraph paragraph;
+late ui.Paragraph paragraph;
 
 ui.Picture paint(ui.Rect paintBounds) {
   final ui.PictureRecorder recorder = ui.PictureRecorder();

examples/layers/raw/touch_input.dart

@@ -8,7 +8,7 @@
 import 'dart:typed_data';
 import 'dart:ui' as ui;
 
-ui.Color color;
+late ui.Color color;
 
 ui.Picture paint(ui.Rect paintBounds) {
   // First we create a PictureRecorder to record the commands we're going to

examples/layers/rendering/custom_coordinate_systems.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.10
-
 // This example shows how to build a render tree with a non-cartesian coordinate
 // system. Most of the guts of this examples are in src/sector_layout.dart.
 

examples/layers/rendering/flex_layout.dart

@@ -48,7 +48,7 @@ void main() {
     subrow.add(RenderSolidColorBox(const Color(0x7FCCFFFF), desiredSize: const Size(30.0, 40.0)));
     row.add(subrow);
     table.add(row);
-    final FlexParentData rowParentData = row.parentData as FlexParentData;
+    final FlexParentData rowParentData = row.parentData! as FlexParentData;
     rowParentData.flex = 1;
   }
 
@@ -71,7 +71,7 @@ void main() {
     row.add(RenderSolidColorBox(const Color(0xFFCCCCFF), desiredSize: const Size(160.0, 60.0)));
     row.mainAxisAlignment = justify;
     table.add(row);
-    final FlexParentData rowParentData = row.parentData as FlexParentData;
+    final FlexParentData rowParentData = row.parentData! as FlexParentData;
     rowParentData.flex = 1;
   }
 

examples/layers/rendering/src/sector_layout.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @dart = 2.10
-
 import 'dart:math' as math;
 
 import 'package:flutter/rendering.dart';

examples/layers/rendering/touch_input.dart

@@ -20,7 +20,7 @@ List<Color> _kColors = <Color>[
 
 /// A simple model object for a dot that reacts to pointer pressure.
 class Dot {
-  Dot({ Color color }) : _paint = Paint()..color = color;
+  Dot({ required Color color }) : _paint = Paint()..color = color;
 
   final Paint _paint;
   Offset position = Offset.zero;
@@ -65,7 +65,7 @@ class RenderDots extends RenderBox {
   @override
   void handleEvent(PointerEvent event, BoxHitTestEntry entry) {
     if (event is PointerDownEvent) {
-      final Color color = _kColors[event.pointer.remainder(_kColors.length) as int];
+      final Color color = _kColors[event.pointer.remainder(_kColors.length)];
       _dots[event.pointer] = Dot(color: color)..update(event);
       // We call markNeedsPaint to indicate that our painting commands have
       // changed and that paint needs to be called before displaying a new frame
@@ -76,7 +76,7 @@ class RenderDots extends RenderBox {
       _dots.remove(event.pointer);
       markNeedsPaint();
     } else if (event is PointerMoveEvent) {
-      _dots[event.pointer].update(event);
+      _dots[event.pointer]!.update(event);
       markNeedsPaint();
     }
   }
@@ -126,7 +126,7 @@ void main() {
   //
   // We use the StackParentData of the paragraph to position the text in the top
   // left corner of the screen.
-  final StackParentData paragraphParentData = paragraph.parentData as StackParentData;
+  final StackParentData paragraphParentData = paragraph.parentData! as StackParentData;
   paragraphParentData
     ..top = 40.0
     ..left = 20.0;

examples/layers/services/isolate.dart

@@ -5,7 +5,6 @@
 import 'dart:convert';
 import 'dart:isolate';
 
-import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
@@ -17,7 +16,7 @@ typedef OnResultListener = void Function(String result);
 // The choice of JSON parsing here is meant as an example that might surface
 // in real-world applications.
 class Calculator {
-  Calculator({ @required this.onProgressListener, @required this.onResultListener, String data })
+  Calculator({ required this.onProgressListener, required this.onResultListener, String? data })
     : assert(onProgressListener != null),
       assert(onResultListener != null),
       // In order to keep the example files smaller, we "cheat" a little and
@@ -53,7 +52,7 @@ class Calculator {
     }
   }
 
-  static String _replicateJson(String data, int count) {
+  static String _replicateJson(String? data, int count) {
     final StringBuffer buffer = StringBuffer()..write('[');
     for (int i = 0; i < count; i++) {
       buffer.write(data);
@@ -85,7 +84,7 @@ class CalculationMessage {
 // This class manages these ports and maintains state related to the
 // progress of the background computation.
 class CalculationManager {
-  CalculationManager({ @required this.onProgressListener, @required this.onResultListener })
+  CalculationManager({ required this.onProgressListener, required this.onResultListener })
     : assert(onProgressListener != null),
       assert(onResultListener != null),
       _receivePort = ReceivePort() {
@@ -120,7 +119,7 @@ class CalculationManager {
     if (isRunning) {
       _state = CalculationState.idle;
       if (_isolate != null) {
-        _isolate.kill(priority: Isolate.immediate);
+        _isolate!.kill(priority: Isolate.immediate);
         _isolate = null;
         _completed = 0.0;
         _total = 1.0;
@@ -129,7 +128,7 @@ class CalculationManager {
   }
 
   final ReceivePort _receivePort;
-  Isolate _isolate;
+  Isolate? _isolate;
 
   void _runCalculation() {
     // Load the JSON string. This is done in the main isolate because spawned
@@ -209,8 +208,8 @@ class IsolateExampleState extends State<StatefulWidget> with SingleTickerProvide
   String _label = 'Start';
   String _result = ' ';
   double _progress = 0.0;
-  AnimationController _animation;
-  CalculationManager _calculationManager;
+  late AnimationController _animation;
+  late CalculationManager _calculationManager;
 
   @override
   void initState() {

examples/layers/services/lifecycle.dart

@@ -5,7 +5,7 @@
 import 'package:flutter/widgets.dart';
 
 class LifecycleWatcher extends StatefulWidget {
-  const LifecycleWatcher({ Key key }) : super(key: key);
+  const LifecycleWatcher({ Key? key }) : super(key: key);
 
   @override
   _LifecycleWatcherState createState() => _LifecycleWatcherState();
@@ -13,17 +13,17 @@ class LifecycleWatcher extends StatefulWidget {
 
 class _LifecycleWatcherState extends State<LifecycleWatcher>
                              with WidgetsBindingObserver {
-  AppLifecycleState _lastLifecycleState;
+  AppLifecycleState? _lastLifecycleState;
 
   @override
   void initState() {
     super.initState();
-    WidgetsBinding.instance.addObserver(this);
+    WidgetsBinding.instance!.addObserver(this);
   }
 
   @override
   void dispose() {
-    WidgetsBinding.instance.removeObserver(this);
+    WidgetsBinding.instance!.removeObserver(this);
     super.dispose();
   }
 

examples/layers/widgets/custom_render_box.dart

@@ -39,7 +39,7 @@ class RenderDots extends RenderConstrainedBox {
 }
 
 class Dots extends SingleChildRenderObjectWidget {
-  const Dots({ Key key, Widget child }) : super(key: key, child: child);
+  const Dots({ Key? key, Widget? child }) : super(key: key, child: child);
 
   @override
   RenderDots createRenderObject(BuildContext context) => RenderDots();

examples/layers/widgets/gestures.dart

@@ -6,14 +6,14 @@ import 'package:flutter/material.dart';
 
 class _GesturePainter extends CustomPainter {
   const _GesturePainter({
-    this.zoom,
-    this.offset,
-    this.swatch,
-    this.forward,
-    this.scaleEnabled,
-    this.tapEnabled,
-    this.doubleTapEnabled,
-    this.longPressEnabled,
+    required this.zoom,
+    required this.offset,
+    required this.swatch,
+    required this.forward,
+    required this.scaleEnabled,
+    required this.tapEnabled,
+    required this.doubleTapEnabled,
+    required this.longPressEnabled,
   });
 
   final double zoom;
@@ -61,12 +61,12 @@ class GestureDemo extends StatefulWidget {
 
 class GestureDemoState extends State<GestureDemo> {
 
-  Offset _startingFocalPoint;
+  late Offset _startingFocalPoint;
 
-  Offset _previousOffset;
+  late Offset _previousOffset;
   Offset _offset = Offset.zero;
 
-  double _previousZoom;
+  late double _previousZoom;
   double _zoom = 1.0;
 
   static const List<MaterialColor> kSwatches = <MaterialColor>[
@@ -175,7 +175,7 @@ class GestureDemoState extends State<GestureDemo> {
                     children: <Widget>[
                       Checkbox(
                         value: _scaleEnabled,
-                        onChanged: (bool value) { setState(() { _scaleEnabled = value; }); },
+                        onChanged: (bool? value) { setState(() { _scaleEnabled = value!; }); },
                       ),
                       const Text('Scale'),
                     ],
@@ -184,7 +184,7 @@ class GestureDemoState extends State<GestureDemo> {
                     children: <Widget>[
                       Checkbox(
                         value: _tapEnabled,
-                        onChanged: (bool value) { setState(() { _tapEnabled = value; }); },
+                        onChanged: (bool? value) { setState(() { _tapEnabled = value!; }); },
                       ),
                       const Text('Tap'),
                     ],
@@ -193,7 +193,7 @@ class GestureDemoState extends State<GestureDemo> {
                     children: <Widget>[
                       Checkbox(
                         value: _doubleTapEnabled,
-                        onChanged: (bool value) { setState(() { _doubleTapEnabled = value; }); },
+                        onChanged: (bool? value) { setState(() { _doubleTapEnabled = value!; }); },
                       ),
                       const Text('Double Tap'),
                     ],
@@ -202,7 +202,7 @@ class GestureDemoState extends State<GestureDemo> {
                     children: <Widget>[
                       Checkbox(
                         value: _longPressEnabled,
-                        onChanged: (bool value) { setState(() { _longPressEnabled = value; }); },
+                        onChanged: (bool? value) { setState(() { _longPressEnabled = value!; }); },
                       ),
                       const Text('Long Press'),
                     ],

examples/layers/widgets/media_query.dart

@@ -5,7 +5,7 @@
 import 'package:flutter/material.dart';
 
 class AdaptedListItem extends StatelessWidget {
-  const AdaptedListItem({ Key key, this.name }) : super(key: key);
+  const AdaptedListItem({ Key? key, required this.name }) : super(key: key);
 
   final String name;
 
@@ -26,7 +26,7 @@ class AdaptedListItem extends StatelessWidget {
 }
 
 class AdaptedGridItem extends StatelessWidget {
-  const AdaptedGridItem({ Key key, this.name }) : super(key: key);
+  const AdaptedGridItem({ Key? key, required this.name }) : super(key: key);
 
   final String name;
 
@@ -65,13 +65,13 @@ const double _kMaxTileWidth = 150.0;
 const double _kGridViewBreakpoint = 450.0;
 
 class AdaptiveContainer extends StatelessWidget {
-  const AdaptiveContainer({ Key key, this.names }) : super(key: key);
+  const AdaptiveContainer({ Key? key, required this.names }) : super(key: key);
 
   final List<String> names;
 
   @override
   Widget build(BuildContext context) {
-    if (MediaQuery.of(context).size.width < _kGridViewBreakpoint) {
+    if (MediaQuery.of(context)!.size.width < _kGridViewBreakpoint) {
       return ListView(
         itemExtent: _kListItemExtent,
         children: names.map<Widget>((String name) => AdaptedListItem(name: name)).toList(),

examples/layers/widgets/sectors.dart

@@ -54,9 +54,9 @@ class SectorAppState extends State<SectorApp> {
     int index = 0;
     while (index < actualSectorSizes.length && index < wantedSectorSizes.length && actualSectorSizes[index] == wantedSectorSizes[index])
       index += 1;
-    final RenderSectorRing ring = sectors.child as RenderSectorRing;
+    final RenderSectorRing ring = sectors.child! as RenderSectorRing;
     while (index < actualSectorSizes.length) {
-      ring.remove(ring.lastChild);
+      ring.remove(ring.lastChild!);
       actualSectorSizes.removeLast();
     }
     while (index < wantedSectorSizes.length) {

examples/layers/widgets/spinning_mixed.dart

@@ -11,13 +11,13 @@ import '../rendering/src/solid_color_box.dart';
 void addFlexChildSolidColor(RenderFlex parent, Color backgroundColor, { int flex = 0 }) {
   final RenderSolidColorBox child = RenderSolidColorBox(backgroundColor);
   parent.add(child);
-  final FlexParentData childParentData = child.parentData as FlexParentData;
+  final FlexParentData childParentData = child.parentData! as FlexParentData;
   childParentData.flex = flex;
 }
 
 // Solid color, Widget version
 class Rectangle extends StatelessWidget {
-  const Rectangle(this.color, { Key key }) : super(key: key);
+  const Rectangle(this.color, { Key? key }) : super(key: key);
 
   final Color color;
 
@@ -31,8 +31,8 @@ class Rectangle extends StatelessWidget {
   }
 }
 
-double value;
-RenderObjectToWidgetElement<RenderBox> element;
+double? value;
+RenderObjectToWidgetElement<RenderBox>? element;
 BuildOwner owner = BuildOwner();
 void attachWidgetTreeToRenderTree(RenderProxyBox container) {
   element = RenderObjectToWidgetAdapter<RenderBox>(
@@ -58,7 +58,7 @@ void attachWidgetTreeToRenderTree(RenderProxyBox container) {
                         ],
                       ),
                       onPressed: () {
-                        value = value == null ? 0.1 : (value + 0.1) % 1.0;
+                        value = value == null ? 0.1 : (value! + 0.1) % 1.0;
                         attachWidgetTreeToRenderTree(container);
                       },
                     ),
@@ -77,17 +77,17 @@ void attachWidgetTreeToRenderTree(RenderProxyBox container) {
   ).attachToRenderTree(owner, element);
 }
 
-Duration timeBase;
-RenderTransform transformBox;
+Duration? timeBase;
+late RenderTransform transformBox;
 
 void rotate(Duration timeStamp) {
   timeBase ??= timeStamp;
-  final double delta = (timeStamp - timeBase).inMicroseconds.toDouble() / Duration.microsecondsPerSecond; // radians
+  final double delta = (timeStamp - timeBase!).inMicroseconds.toDouble() / Duration.microsecondsPerSecond; // radians
 
   transformBox.setIdentity();
   transformBox.rotateZ(delta);
 
-  owner.buildScope(element);
+  owner.buildScope(element!);
 }
 
 void main() {

examples/layers/widgets/spinning_square.dart

@@ -10,7 +10,7 @@ class SpinningSquare extends StatefulWidget {
 }
 
 class _SpinningSquareState extends State<SpinningSquare> with SingleTickerProviderStateMixin {
-  AnimationController _animation;
+  late AnimationController _animation;
 
   @override
   void initState() {

examples/layers/widgets/styled_text.dart

@@ -78,13 +78,7 @@ class StyledTextDemo extends StatefulWidget {
 }
 
 class _StyledTextDemoState extends State<StyledTextDemo> {
-  @override
-  void initState() {
-    super.initState();
-    _toText = toStyledText;
-  }
-
-  _TextTransformer _toText;
+  _TextTransformer _toText = toStyledText;
 
   void _handleTap() {
     setState(() {