flutter · auto-submit · Oct 31, 2022 · Oct 27, 2022 · Oct 27, 2022 · Oct 27, 2022
diff --git a/dev/integration_tests/flutter_gallery/lib/demo/material/expansion_panels_demo.dart b/dev/integration_tests/flutter_gallery/lib/demo/material/expansion_panels_demo.dart
@@ -210,8 +210,8 @@ class _ExpansionPanelsDemoState extends State<ExpansionPanelsDemo> {
               builder: (BuildContext context) {
                 return CollapsibleBody(
                   margin: const EdgeInsets.symmetric(horizontal: 16.0),
-                  onSave: () { Form.of(context)!.save(); close(); },
-                  onCancel: () { Form.of(context)!.reset(); close(); },
+                  onSave: () { Form.of(context).save(); close(); },
+                  onCancel: () { Form.of(context).reset(); close(); },
                   child: Padding(
                     padding: const EdgeInsets.symmetric(horizontal: 16.0),
                     child: TextFormField(
@@ -244,8 +244,8 @@ class _ExpansionPanelsDemoState extends State<ExpansionPanelsDemo> {
             child: Builder(
               builder: (BuildContext context) {
                 return CollapsibleBody(
-                  onSave: () { Form.of(context)!.save(); close(); },
-                  onCancel: () { Form.of(context)!.reset(); close(); },
+                  onSave: () { Form.of(context).save(); close(); },
+                  onCancel: () { Form.of(context).reset(); close(); },
                   child: FormField<Location>(
                     initialValue: item.value,
                     onSaved: (Location? result) { item.value = result; },
@@ -298,8 +298,8 @@ class _ExpansionPanelsDemoState extends State<ExpansionPanelsDemo> {
             child: Builder(
               builder: (BuildContext context) {
                 return CollapsibleBody(
-                  onSave: () { Form.of(context)!.save(); close(); },
-                  onCancel: () { Form.of(context)!.reset(); close(); },
+                  onSave: () { Form.of(context).save(); close(); },
+                  onCancel: () { Form.of(context).reset(); close(); },
                   child: FormField<double>(
                     initialValue: item.value,
                     onSaved: (double? value) { item.value = value; },

diff --git a/dev/integration_tests/flutter_gallery/lib/demo/material/page_selector_demo.dart b/dev/integration_tests/flutter_gallery/lib/demo/material/page_selector_demo.dart
@@ -12,15 +12,15 @@ class _PageSelector extends StatelessWidget {
   final List<Icon>? icons;
 
   void _handleArrowButtonPress(BuildContext context, int delta) {
-    final TabController controller = DefaultTabController.of(context)!;
+    final TabController controller = DefaultTabController.of(context);
     if (!controller.indexIsChanging) {
       controller.animateTo((controller.index + delta).clamp(0, icons!.length - 1));
     }
   }
 
   @override
   Widget build(BuildContext context) {
-    final TabController? controller = DefaultTabController.of(context);
+    final TabController? controller = DefaultTabController.maybeOf(context);
     final Color color = Theme.of(context).colorScheme.secondary;
     return SafeArea(
       top: false,

diff --git a/dev/integration_tests/flutter_gallery/lib/gallery/demo.dart b/dev/integration_tests/flutter_gallery/lib/gallery/demo.dart
@@ -63,7 +63,7 @@ class TabbedComponentDemoScaffold extends StatefulWidget {
 
 class _TabbedComponentDemoScaffoldState extends State<TabbedComponentDemoScaffold> {
   void _showExampleCode(BuildContext context) {
-    final String? tag = widget.demos![DefaultTabController.of(context)!.index].exampleCodeTag;
+    final String? tag = widget.demos![DefaultTabController.of(context).index].exampleCodeTag;
     if (tag != null) {
       Navigator.push(context, MaterialPageRoute<FullScreenCodeDialog>(
         builder: (BuildContext context) => FullScreenCodeDialog(exampleCodeTag: tag)
@@ -72,7 +72,7 @@ class _TabbedComponentDemoScaffoldState extends State<TabbedComponentDemoScaffol
   }
 
   Future<void> _showApiDocumentation(BuildContext context) async {
-    final String? url = widget.demos![DefaultTabController.of(context)!.index].documentationUrl;
+    final String? url = widget.demos![DefaultTabController.of(context).index].documentationUrl;
     if (url == null) {
       return;
     }

diff --git a/dev/manual_tests/lib/material_arc.dart b/dev/manual_tests/lib/material_arc.dart
@@ -451,7 +451,7 @@ class _AnimationDemoState extends State<AnimationDemo> with TickerProviderStateM
             return FloatingActionButton(
               child: const Icon(Icons.refresh),
               onPressed: () {
-                _play(_allDemos[DefaultTabController.of(context)!.index]);
+                _play(_allDemos[DefaultTabController.of(context).index]);
               },
             );
           },

diff --git a/dev/manual_tests/lib/overlay_geometry.dart b/dev/manual_tests/lib/overlay_geometry.dart
@@ -172,8 +172,8 @@ class OverlayGeometryAppState extends State<OverlayGeometryApp> {
       markers[MarkerType.topLeft] = box!.localToGlobal(Offset.zero);
       final Size size = box.size;
       markers[MarkerType.bottomRight] = box.localToGlobal(Offset(size.width, size.height));
-      final ScrollableState? scrollable = Scrollable.of(target.currentContext!);
-      markersScrollOffset = scrollable!.position.pixels;
+      final ScrollableState scrollable = Scrollable.of(target.currentContext!);
+      markersScrollOffset = scrollable.position.pixels;
     });
   }
 

diff --git a/examples/api/lib/cupertino/text_form_field_row/cupertino_text_form_field_row.1.dart b/examples/api/lib/cupertino/text_form_field_row/cupertino_text_form_field_row.1.dart
@@ -34,7 +34,7 @@ class FromSectionExample extends StatelessWidget {
         child: Form(
           autovalidateMode: AutovalidateMode.always,
           onChanged: () {
-            Form.of(primaryFocus!.context!)?.save();
+            Form.maybeOf(primaryFocus!.context!)?.save();
           },
           child: CupertinoFormSection.insetGrouped(
             header: const Text('SECTION 1'),

diff --git a/examples/api/lib/material/tab_controller/tab_controller.1.dart b/examples/api/lib/material/tab_controller/tab_controller.1.dart
@@ -38,7 +38,7 @@ class MyStatelessWidget extends StatelessWidget {
       // The Builder widget is used to have a different BuildContext to access
       // closest DefaultTabController.
       child: Builder(builder: (BuildContext context) {
-        final TabController tabController = DefaultTabController.of(context)!;
+        final TabController tabController = DefaultTabController.of(context);
         tabController.addListener(() {
           if (!tabController.indexIsChanging) {
             // Your code goes here.

diff --git a/examples/api/lib/material/text_form_field/text_form_field.1.dart b/examples/api/lib/material/text_form_field/text_form_field.1.dart
@@ -44,7 +44,7 @@ class _MyStatefulWidgetState extends State<MyStatefulWidget> {
             child: Form(
               autovalidateMode: AutovalidateMode.always,
               onChanged: () {
-                Form.of(primaryFocus!.context!)!.save();
+                Form.of(primaryFocus!.context!).save();
               },
               child: Wrap(
                 children: List<Widget>.generate(5, (int index) {

diff --git a/packages/flutter/lib/src/cupertino/page_scaffold.dart b/packages/flutter/lib/src/cupertino/page_scaffold.dart
@@ -90,7 +90,7 @@ class CupertinoPageScaffold extends StatefulWidget {
 class _CupertinoPageScaffoldState extends State<CupertinoPageScaffold> {
 
   void _handleStatusBarTap() {
-    final ScrollController? primaryScrollController = PrimaryScrollController.of(context);
+    final ScrollController? primaryScrollController = PrimaryScrollController.maybeOf(context);
     // Only act on the scroll controller if it has any attached scroll positions.
     if (primaryScrollController != null && primaryScrollController.hasClients) {
       primaryScrollController.animateTo(

diff --git a/packages/flutter/lib/src/material/about.dart b/packages/flutter/lib/src/material/about.dart
@@ -602,7 +602,7 @@ class _PackagesViewState extends State<_PackagesView> {
     }
     final String packageName = data.packages[widget.selectedId.value ?? 0];
     final List<int> bindings = data.packageLicenseBindings[packageName]!;
-    _MasterDetailFlow.of(context)!.setInitialDetailPage(
+    _MasterDetailFlow.of(context).setInitialDetailPage(
       _DetailArguments(
         packageName,
         bindings.map((int i) => data.licenses[i]).toList(growable: false),
@@ -632,7 +632,7 @@ class _PackagesViewState extends State<_PackagesView> {
           numberLicenses: bindings.length,
           onTap: () {
             widget.selectedId.value = packageIndex;
-            _MasterDetailFlow.of(context)!.openDetailPage(_DetailArguments(
+            _MasterDetailFlow.of(context).openDetailPage(_DetailArguments(
               packageName,
               bindings.map((int i) => data.licenses[i]).toList(growable: false),
             ));
@@ -1073,7 +1073,7 @@ class _MasterDetailFlow extends StatefulWidget {
   // ```dart
   // _MasterDetailFlow.of(context).openDetailPage(arguments);
   // ```
-  static _MasterDetailFlowProxy? of(BuildContext context) {
+  static _MasterDetailFlowProxy of(BuildContext context) {
     _PageOpener? pageOpener = context.findAncestorStateOfType<_MasterDetailScaffoldState>();
     pageOpener ??= context.findAncestorStateOfType<_MasterDetailFlowState>();
     assert(() {
@@ -1086,7 +1086,7 @@ class _MasterDetailFlow extends StatefulWidget {
       }
       return true;
     }());
-    return pageOpener != null ? _MasterDetailFlowProxy._(pageOpener) : null;
+    return _MasterDetailFlowProxy._(pageOpener!);
   }
 }
 
@@ -1339,13 +1339,13 @@ class _MasterDetailScaffoldState extends State<_MasterDetailScaffold>
   @override
   void openDetailPage(Object arguments) {
     SchedulerBinding.instance.addPostFrameCallback((_) => _detailArguments.value = arguments);
-    _MasterDetailFlow.of(context)!.openDetailPage(arguments);
+    _MasterDetailFlow.of(context).openDetailPage(arguments);
   }
 
   @override
   void setInitialDetailPage(Object arguments) {
     SchedulerBinding.instance.addPostFrameCallback((_) => _detailArguments.value = arguments);
-    _MasterDetailFlow.of(context)!.setInitialDetailPage(arguments);
+    _MasterDetailFlow.of(context).setInitialDetailPage(arguments);
   }
 
   @override

diff --git a/packages/flutter/lib/src/material/app_bar.dart b/packages/flutter/lib/src/material/app_bar.dart
@@ -820,13 +820,9 @@ class _AppBarState extends State<AppBar> {
   @override
   void didChangeDependencies() {
     super.didChangeDependencies();
-    if (_scrollNotificationObserver != null) {
-      _scrollNotificationObserver!.removeListener(_handleScrollNotification);
-    }
-    _scrollNotificationObserver = ScrollNotificationObserver.of(context);
-    if (_scrollNotificationObserver != null) {
-      _scrollNotificationObserver!.addListener(_handleScrollNotification);
-    }
+    _scrollNotificationObserver?.removeListener(_handleScrollNotification);
+    _scrollNotificationObserver = ScrollNotificationObserver.maybeOf(context);
+    _scrollNotificationObserver?.addListener(_handleScrollNotification);
   }
 
   @override

diff --git a/packages/flutter/lib/src/material/calendar_date_picker.dart b/packages/flutter/lib/src/material/calendar_date_picker.dart
@@ -806,7 +806,7 @@ class _FocusedDate extends InheritedWidget {
     return !DateUtils.isSameDay(date, oldWidget.date);
   }
 
-  static DateTime? of(BuildContext context) {
+  static DateTime? maybeOf(BuildContext context) {
     final _FocusedDate? focusedDate = context.dependOnInheritedWidgetOfExactType<_FocusedDate>();
     return focusedDate?.date;
   }
@@ -887,7 +887,7 @@ class _DayPickerState extends State<_DayPicker> {
   void didChangeDependencies() {
     super.didChangeDependencies();
     // Check to see if the focused date is in this month, if so focus it.
-    final DateTime? focusedDate = _FocusedDate.of(context);
+    final DateTime? focusedDate = _FocusedDate.maybeOf(context);
     if (focusedDate != null && DateUtils.isSameMonth(widget.displayedMonth, focusedDate)) {
       _dayFocusNodes[focusedDate.day - 1].requestFocus();
     }

diff --git a/packages/flutter/lib/src/material/date_picker.dart b/packages/flutter/lib/src/material/date_picker.dart
@@ -1940,12 +1940,11 @@ class _FocusedDate extends InheritedWidget {
     return !DateUtils.isSameDay(date, oldWidget.date) || scrollDirection != oldWidget.scrollDirection;
   }
 
-  static _FocusedDate? of(BuildContext context) {
+  static _FocusedDate? maybeOf(BuildContext context) {
     return context.dependOnInheritedWidgetOfExactType<_FocusedDate>();
   }
 }
 
-
 class _DayHeaders extends StatelessWidget {
   const _DayHeaders();
 
@@ -2217,7 +2216,7 @@ class _MonthItemState extends State<_MonthItem> {
   void didChangeDependencies() {
     super.didChangeDependencies();
     // Check to see if the focused date is in this month, if so focus it.
-    final DateTime? focusedDate = _FocusedDate.of(context)?.date;
+    final DateTime? focusedDate = _FocusedDate.maybeOf(context)?.date;
     if (focusedDate != null && DateUtils.isSameMonth(widget.displayedMonth, focusedDate)) {
       _dayFocusNodes[focusedDate.day - 1].requestFocus();
     }
@@ -2237,7 +2236,7 @@ class _MonthItemState extends State<_MonthItem> {
 
   void _dayFocusChanged(bool focused) {
     if (focused) {
-      final TraversalDirection? focusDirection = _FocusedDate.of(context)?.scrollDirection;
+      final TraversalDirection? focusDirection = _FocusedDate.maybeOf(context)?.scrollDirection;
       if (focusDirection != null) {
         ScrollPositionAlignmentPolicy policy = ScrollPositionAlignmentPolicy.explicit;
         switch (focusDirection) {

diff --git a/packages/flutter/lib/src/material/expansion_tile.dart b/packages/flutter/lib/src/material/expansion_tile.dart
@@ -332,7 +332,7 @@ class _ExpansionTileState extends State<ExpansionTile> with SingleTickerProvider
     _iconColor = _controller.drive(_iconColorTween.chain(_easeInTween));
     _backgroundColor = _controller.drive(_backgroundColorTween.chain(_easeOutTween));
 
-    _isExpanded = PageStorage.of(context)?.readState(context) as bool? ?? widget.initiallyExpanded;
+    _isExpanded = PageStorage.maybeOf(context)?.readState(context) as bool? ?? widget.initiallyExpanded;
     if (_isExpanded) {
       _controller.value = 1.0;
     }
@@ -359,7 +359,7 @@ class _ExpansionTileState extends State<ExpansionTile> with SingleTickerProvider
           });
         });
       }
-      PageStorage.of(context)?.writeState(context, _isExpanded);
+      PageStorage.maybeOf(context)?.writeState(context, _isExpanded);
     });
     widget.onExpansionChanged?.call(_isExpanded);
   }

diff --git a/packages/flutter/lib/src/material/ink_decoration.dart b/packages/flutter/lib/src/material/ink_decoration.dart
@@ -284,7 +284,7 @@ class _InkState extends State<Ink> {
       _ink = InkDecoration(
         decoration: widget.decoration,
         configuration: createLocalImageConfiguration(context),
-        controller: Material.of(context)!,
+        controller: Material.of(context),
         referenceBox: _boxKey.currentContext!.findRenderObject()! as RenderBox,
         onRemoved: _handleRemoved,
       );

diff --git a/packages/flutter/lib/src/material/ink_well.dart b/packages/flutter/lib/src/material/ink_well.dart
@@ -197,7 +197,7 @@ class _ParentInkResponseProvider extends InheritedWidget {
   @override
   bool updateShouldNotify(_ParentInkResponseProvider oldWidget) => state != oldWidget.state;
 
-  static _ParentInkResponseState? of(BuildContext context) {
+  static _ParentInkResponseState? maybeOf(BuildContext context) {
     return context.dependOnInheritedWidgetOfExactType<_ParentInkResponseProvider>()?.state;
   }
 }
@@ -600,7 +600,7 @@ class InkResponse extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final _ParentInkResponseState? parentState = _ParentInkResponseProvider.of(context);
+    final _ParentInkResponseState? parentState = _ParentInkResponseProvider.maybeOf(context);
     return _InkResponseStateWidget(
       onTap: onTap,
       onTapDown: onTapDown,
@@ -916,7 +916,7 @@ class _InkResponseState extends State<_InkResponseStateWidget>
         }
         final RenderBox referenceBox = context.findRenderObject()! as RenderBox;
         _highlights[type] = InkHighlight(
-          controller: Material.of(context)!,
+          controller: Material.of(context),
           referenceBox: referenceBox,
           color: resolvedOverlayColor,
           shape: widget.highlightShape,
@@ -952,7 +952,7 @@ class _InkResponseState extends State<_InkResponseStateWidget>
   }
 
   InteractiveInkFeature _createInkFeature(Offset globalPosition) {
-    final MaterialInkController inkController = Material.of(context)!;
+    final MaterialInkController inkController = Material.of(context);
     final RenderBox referenceBox = context.findRenderObject()! as RenderBox;
     final Offset position = referenceBox.globalToLocal(globalPosition);
     final Color color =  widget.overlayColor?.resolve(statesController.value) ?? widget.splashColor ?? Theme.of(context).splashColor;

diff --git a/packages/flutter/lib/src/material/material.dart b/packages/flutter/lib/src/material/material.dart
@@ -348,14 +348,55 @@ class Material extends StatefulWidget {
   /// Typical usage is as follows:
   ///
   /// ```dart
-  /// MaterialInkController? inkController = Material.of(context);
+  /// MaterialInkController? inkController = Material.maybeOf(context);
   /// ```
   ///
   /// This method can be expensive (it walks the element tree).
-  static MaterialInkController? of(BuildContext context) {
+  ///
+  /// See also:
+  ///
+  /// * [Material.of], which is similar to this method, but asserts if
+  ///   no [Material] ancestor is found.
+  static MaterialInkController? maybeOf(BuildContext context) {
     return context.findAncestorRenderObjectOfType<_RenderInkFeatures>();
   }
 
+  /// The ink controller from the closest instance of [Material] that encloses
+  /// the given context.
+  ///
+  /// If no [Material] widget ancestor can be found then this method will assert
+  /// in debug mode, and throw an exception in release mode.
+  ///
+  /// Typical usage is as follows:
+  ///
+  /// ```dart
+  /// MaterialInkController inkController = Material.of(context);
+  /// ```
+  ///
+  /// This method can be expensive (it walks the element tree).
+  ///
+  /// See also:
+  ///
+  /// * [Material.maybeOf], which is similar to this method, but returns null if
+  ///   no [Material] ancestor is found.
+  static MaterialInkController of(BuildContext context) {
+    final MaterialInkController? controller = maybeOf(context);
+    assert(() {
+      if (controller == null) {
+        throw FlutterError(
+          'Material.of() was called with a context that does not contain a Material widget.\n'
+          'No Material widget ancestor could be found starting from the context that was passed to '
+          'Material.of(). This can happen because you are using a widget that looks for a Material '
+          'ancestor, but no such ancestor exists.\n'
+          'The context used was:\n'
+          '  $context',
+        );
+      }
+      return true;
+    }());
+    return controller!;
+  }
+
   @override
   State<Material> createState() => _MaterialState();
 

diff --git a/packages/flutter/lib/src/material/menu_anchor.dart b/packages/flutter/lib/src/material/menu_anchor.dart
@@ -305,7 +305,7 @@ class _MenuAnchorState extends State<MenuAnchor> {
     _parent = _MenuAnchorState._maybeOf(context);
     _parent?._addChild(this);
     _position?.isScrollingNotifier.removeListener(_handleScroll);
-    _position = Scrollable.of(context)?.position;
+    _position = Scrollable.maybeOf(context)?.position;
     _position?.isScrollingNotifier.addListener(_handleScroll);
     final Size newSize = MediaQuery.of(context).size;
     if (_viewSize != null && newSize != _viewSize) {

diff --git a/packages/flutter/lib/src/material/paginated_data_table.dart b/packages/flutter/lib/src/material/paginated_data_table.dart
@@ -267,7 +267,7 @@ class PaginatedDataTableState extends State<PaginatedDataTable> {
   @override
   void initState() {
     super.initState();
-    _firstRowIndex = PageStorage.of(context)?.readState(context) as int? ?? widget.initialFirstRowIndex ?? 0;
+    _firstRowIndex = PageStorage.maybeOf(context)?.readState(context) as int? ?? widget.initialFirstRowIndex ?? 0;
     widget.source.addListener(_handleDataSourceChanged);
     _handleDataSourceChanged();
   }

diff --git a/packages/flutter/lib/src/material/scaffold.dart b/packages/flutter/lib/src/material/scaffold.dart
@@ -2536,7 +2536,7 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin, Resto
   // top. We implement this by looking up the primary scroll controller and
   // scrolling it to the top when tapped.
   void _handleStatusBarTap() {
-    final ScrollController? primaryScrollController = PrimaryScrollController.of(context);
+    final ScrollController? primaryScrollController = PrimaryScrollController.maybeOf(context);
     if (primaryScrollController != null && primaryScrollController.hasClients) {
       primaryScrollController.animateTo(
         0.0,