Add Directionality.maybeOf (#69117)

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

@@ -1834,7 +1834,7 @@ class _RawChipState extends State<RawChip> with TickerProviderStateMixin<RawChip
 
     final ThemeData theme = Theme.of(context)!;
     final ChipThemeData chipTheme = ChipTheme.of(context);
-    final TextDirection? textDirection = Directionality.of(context);
+    final TextDirection? textDirection = Directionality.maybeOf(context);
     final ShapeBorder shape = widget.shape ?? chipTheme.shape;
     final double elevation = widget.elevation ?? chipTheme.elevation ?? _defaultElevation;
     final double pressElevation = widget.pressElevation ?? chipTheme.pressElevation ?? _defaultPressElevation;

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

@@ -469,7 +469,7 @@ class AlertDialog extends StatelessWidget {
     // The paddingScaleFactor is used to adjust the padding of Dialog's
     // children.
     final double paddingScaleFactor = _paddingScaleFactor(MediaQuery.of(context)!.textScaleFactor);
-    final TextDirection? textDirection = Directionality.of(context);
+    final TextDirection? textDirection = Directionality.maybeOf(context);
 
     Widget? titleWidget;
     Widget? contentWidget;
@@ -826,7 +826,7 @@ class SimpleDialog extends StatelessWidget {
     // The paddingScaleFactor is used to adjust the padding of Dialog
     // children.
     final double paddingScaleFactor = _paddingScaleFactor(MediaQuery.of(context)!.textScaleFactor);
-    final TextDirection? textDirection = Directionality.of(context);
+    final TextDirection? textDirection = Directionality.maybeOf(context);
 
     Widget? titleWidget;
     if (title != null) {

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

@@ -499,11 +499,11 @@ class DrawerControllerState extends State<DrawerController> with SingleTickerPro
   Widget _buildDrawer(BuildContext context) {
     final bool drawerIsStart = widget.alignment == DrawerAlignment.start;
     final EdgeInsets padding = MediaQuery.of(context)!.padding;
-    final TextDirection? textDirection = Directionality.of(context);
+    final TextDirection textDirection = Directionality.of(context)!;
 
     double? dragAreaWidth = widget.edgeDragWidth;
     if (widget.edgeDragWidth == null) {
-      switch (textDirection!) {
+      switch (textDirection) {
         case TextDirection.ltr:
           dragAreaWidth = _kEdgeDragWidth +
             (drawerIsStart ? padding.left : padding.right);

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

@@ -564,7 +564,7 @@ class _DropdownRoutePage<T> extends StatelessWidget {
       route.scrollController = ScrollController(initialScrollOffset: menuLimits.scrollOffset);
     }
 
-    final TextDirection? textDirection = Directionality.of(context);
+    final TextDirection? textDirection = Directionality.maybeOf(context);
     final Widget menu = _DropdownMenu<T>(
       route: route,
       padding: padding.resolve(textDirection),
@@ -1178,7 +1178,7 @@ class _DropdownButtonState<T> extends State<DropdownButton<T>> with WidgetsBindi
   void _handleTap() {
     final RenderBox itemBox = context.findRenderObject()! as RenderBox;
     final Rect itemRect = itemBox.localToGlobal(Offset.zero) & itemBox.size;
-    final TextDirection? textDirection = Directionality.of(context);
+    final TextDirection? textDirection = Directionality.maybeOf(context);
     final EdgeInsetsGeometry menuMargin = ButtonTheme.of(context).alignedDropdown
       ? _kAlignedMenuMargin
       : _kUnalignedMenuMargin;

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

@@ -453,7 +453,7 @@ class _MaterialState extends State<Material> with TickerProviderStateMixin {
       child: child,
       clipper: ShapeBorderClipper(
         shape: shape,
-        textDirection: Directionality.of(context),
+        textDirection: Directionality.maybeOf(context),
       ),
       clipBehavior: clipBehavior,
     );
@@ -787,7 +787,7 @@ class _MaterialInteriorState extends AnimatedWidgetBaseState<_MaterialInterior>
       ),
       clipper: ShapeBorderClipper(
         shape: shape,
-        textDirection: Directionality.of(context),
+        textDirection: Directionality.maybeOf(context),
       ),
       clipBehavior: widget.clipBehavior,
       elevation: elevation,
@@ -812,8 +812,8 @@ class _ShapeBorderPaint extends StatelessWidget {
   Widget build(BuildContext context) {
     return CustomPaint(
       child: child,
-      painter: borderOnForeground ? null : _ShapeBorderPainter(shape, Directionality.of(context)),
-      foregroundPainter: borderOnForeground ? _ShapeBorderPainter(shape, Directionality.of(context)) : null,
+      painter: borderOnForeground ? null : _ShapeBorderPainter(shape, Directionality.maybeOf(context)),
+      foregroundPainter: borderOnForeground ? _ShapeBorderPainter(shape, Directionality.maybeOf(context)) : null,
     );
   }
 }

packages/flutter/lib/src/material/pickers/calendar_date_picker.dart

@@ -494,7 +494,7 @@ class _MonthPickerState extends State<_MonthPicker> {
   late DateTime _previousMonthDate;
   PageController? _pageController;
   late MaterialLocalizations _localizations;
-  TextDirection? _textDirection;
+  late TextDirection _textDirection;
   Map<LogicalKeySet, Intent>? _shortcutMap;
   Map<Type, Action<Intent>>? _actionMap;
   FocusNode? _dayGridFocus;
@@ -525,7 +525,7 @@ class _MonthPickerState extends State<_MonthPicker> {
   void didChangeDependencies() {
     super.didChangeDependencies();
     _localizations = MaterialLocalizations.of(context);
-    _textDirection = Directionality.of(context);
+    _textDirection = Directionality.of(context)!;
   }
 
   @override
@@ -595,7 +595,7 @@ class _MonthPickerState extends State<_MonthPicker> {
     if (!_isDisplayingLastMonth) {
       SemanticsService.announce(
         _localizations.formatMonthYear(_nextMonthDate),
-        _textDirection!,
+        _textDirection,
       );
       _pageController!.nextPage(
         duration: _monthScrollDuration,
@@ -609,7 +609,7 @@ class _MonthPickerState extends State<_MonthPicker> {
     if (!_isDisplayingFirstMonth) {
       SemanticsService.announce(
         _localizations.formatMonthYear(_previousMonthDate),
-        _textDirection!,
+        _textDirection,
       );
       _pageController!.previousPage(
         duration: _monthScrollDuration,

packages/flutter/lib/src/material/pickers/calendar_date_range_picker.dart

@@ -707,7 +707,7 @@ class _MonthItemState extends State<_MonthItem> {
     final ColorScheme colorScheme = theme.colorScheme;
     final TextTheme textTheme = theme.textTheme;
     final MaterialLocalizations localizations = MaterialLocalizations.of(context);
-    final TextDirection? textDirection = Directionality.of(context);
+    final TextDirection textDirection = Directionality.of(context)!;
     final Color highlightColor = _highlightColor(context);
     final int day = dayToBuild.day;
 

packages/flutter/lib/src/widgets/animated_size.dart

@@ -116,7 +116,7 @@ class AnimatedSize extends SingleChildRenderObjectWidget {
       reverseDuration: reverseDuration,
       curve: curve,
       vsync: vsync,
-      textDirection: Directionality.of(context),
+      textDirection: Directionality.maybeOf(context),
       clipBehavior: clipBehavior,
     );
   }
@@ -129,7 +129,7 @@ class AnimatedSize extends SingleChildRenderObjectWidget {
       ..reverseDuration = reverseDuration
       ..curve = curve
       ..vsync = vsync
-      ..textDirection = Directionality.of(context)
+      ..textDirection = Directionality.maybeOf(context)
       ..clipBehavior = clipBehavior;
   }
 

packages/flutter/lib/src/widgets/basic.dart

@@ -107,11 +107,28 @@ class Directionality extends InheritedWidget {
   /// ```dart
   /// TextDirection textDirection = Directionality.of(context);
   /// ```
+  // TODO(goderbauer): Make this non-null when customers have upgraded to Directionality.maybeOf.
   static TextDirection? of(BuildContext context) {
     final Directionality? widget = context.dependOnInheritedWidgetOfExactType<Directionality>();
     return widget?.textDirection;
   }
 
+  /// The text direction from the closest instance of this class that encloses
+  /// the given context.
+  ///
+  /// If there is no [Directionality] ancestor widget in the tree at the given
+  /// context, then this will return null.
+  ///
+  /// Typical usage is as follows:
+  ///
+  /// ```dart
+  /// TextDirection? textDirection = Directionality.maybeOf(context);
+  /// ```
+  static TextDirection? maybeOf(BuildContext context) {
+    final Directionality? widget = context.dependOnInheritedWidgetOfExactType<Directionality>();
+    return widget?.textDirection;
+  }
+
   @override
   bool updateShouldNotify(Directionality oldWidget) => textDirection != oldWidget.textDirection;
 
@@ -831,7 +848,7 @@ class ClipPath extends SingleChildRenderObjectWidget {
         return ClipPath(
           clipper: ShapeBorderClipper(
             shape: shape,
-            textDirection: Directionality.of(context),
+            textDirection: Directionality.maybeOf(context),
           ),
           clipBehavior: clipBehavior,
           child: child,
@@ -1258,7 +1275,7 @@ class Transform extends SingleChildRenderObjectWidget {
       transform: transform,
       origin: origin,
       alignment: alignment,
-      textDirection: Directionality.of(context),
+      textDirection: Directionality.maybeOf(context),
       transformHitTests: transformHitTests,
     );
   }
@@ -1269,7 +1286,7 @@ class Transform extends SingleChildRenderObjectWidget {
       ..transform = transform
       ..origin = origin
       ..alignment = alignment
-      ..textDirection = Directionality.of(context)
+      ..textDirection = Directionality.maybeOf(context)
       ..transformHitTests = transformHitTests;
   }
 }
@@ -1495,7 +1512,7 @@ class FittedBox extends SingleChildRenderObjectWidget {
     return RenderFittedBox(
       fit: fit,
       alignment: alignment,
-      textDirection: Directionality.of(context),
+      textDirection: Directionality.maybeOf(context),
       clipBehavior: clipBehavior,
     );
   }
@@ -1505,7 +1522,7 @@ class FittedBox extends SingleChildRenderObjectWidget {
     renderObject
       ..fit = fit
       ..alignment = alignment
-      ..textDirection = Directionality.of(context)
+      ..textDirection = Directionality.maybeOf(context)
       ..clipBehavior = clipBehavior;
   }
 
@@ -1689,7 +1706,7 @@ class Padding extends SingleChildRenderObjectWidget {
   RenderPadding createRenderObject(BuildContext context) {
     return RenderPadding(
       padding: padding,
-      textDirection: Directionality.of(context),
+      textDirection: Directionality.maybeOf(context),
     );
   }
 
@@ -1697,7 +1714,7 @@ class Padding extends SingleChildRenderObjectWidget {
   void updateRenderObject(BuildContext context, RenderPadding renderObject) {
     renderObject
       ..padding = padding
-      ..textDirection = Directionality.of(context);
+      ..textDirection = Directionality.maybeOf(context);
   }
 
   @override
@@ -1884,7 +1901,7 @@ class Align extends SingleChildRenderObjectWidget {
       alignment: alignment,
       widthFactor: widthFactor,
       heightFactor: heightFactor,
-      textDirection: Directionality.of(context),
+      textDirection: Directionality.maybeOf(context),
     );
   }
 
@@ -1894,7 +1911,7 @@ class Align extends SingleChildRenderObjectWidget {
       ..alignment = alignment
       ..widthFactor = widthFactor
       ..heightFactor = heightFactor
-      ..textDirection = Directionality.of(context);
+      ..textDirection = Directionality.maybeOf(context);
   }
 
   @override
@@ -2334,7 +2351,7 @@ class UnconstrainedBox extends SingleChildRenderObjectWidget {
   @override
   void updateRenderObject(BuildContext context, covariant RenderUnconstrainedBox renderObject) {
     renderObject
-      ..textDirection = textDirection ?? Directionality.of(context)
+      ..textDirection = textDirection ?? Directionality.maybeOf(context)
       ..alignment = alignment
       ..constrainedAxis = constrainedAxis
       ..clipBehavior = clipBehavior;
@@ -2342,7 +2359,7 @@ class UnconstrainedBox extends SingleChildRenderObjectWidget {
 
   @override
   RenderUnconstrainedBox createRenderObject(BuildContext context) => RenderUnconstrainedBox(
-    textDirection: textDirection ?? Directionality.of(context),
+    textDirection: textDirection ?? Directionality.maybeOf(context),
     alignment: alignment,
     constrainedAxis: constrainedAxis,
     clipBehavior: clipBehavior,
@@ -2431,7 +2448,7 @@ class FractionallySizedBox extends SingleChildRenderObjectWidget {
       alignment: alignment,
       widthFactor: widthFactor,
       heightFactor: heightFactor,
-      textDirection: Directionality.of(context),
+      textDirection: Directionality.maybeOf(context),
     );
   }
 
@@ -2441,7 +2458,7 @@ class FractionallySizedBox extends SingleChildRenderObjectWidget {
       ..alignment = alignment
       ..widthFactor = widthFactor
       ..heightFactor = heightFactor
-      ..textDirection = Directionality.of(context);
+      ..textDirection = Directionality.maybeOf(context);
   }
 
   @override
@@ -2594,7 +2611,7 @@ class OverflowBox extends SingleChildRenderObjectWidget {
       maxWidth: maxWidth,
       minHeight: minHeight,
       maxHeight: maxHeight,
-      textDirection: Directionality.of(context),
+      textDirection: Directionality.maybeOf(context),
     );
   }
 
@@ -2606,7 +2623,7 @@ class OverflowBox extends SingleChildRenderObjectWidget {
       ..maxWidth = maxWidth
       ..minHeight = minHeight
       ..maxHeight = maxHeight
-      ..textDirection = Directionality.of(context);
+      ..textDirection = Directionality.maybeOf(context);
   }
 
   @override
@@ -3400,7 +3417,7 @@ class Stack extends MultiChildRenderObjectWidget {
     assert(_debugCheckHasDirectionality(context));
     return RenderStack(
       alignment: alignment,
-      textDirection: textDirection ?? Directionality.of(context),
+      textDirection: textDirection ?? Directionality.maybeOf(context),
       fit: fit,
       clipBehavior: overflow == Overflow.visible ? Clip.none : clipBehavior,
     );
@@ -3411,7 +3428,7 @@ class Stack extends MultiChildRenderObjectWidget {
     assert(_debugCheckHasDirectionality(context));
     renderObject
       ..alignment = alignment
-      ..textDirection = textDirection ?? Directionality.of(context)
+      ..textDirection = textDirection ?? Directionality.maybeOf(context)
       ..fit = fit
       ..clipBehavior = overflow == Overflow.visible ? Clip.none : clipBehavior;
   }
@@ -3461,7 +3478,7 @@ class IndexedStack extends Stack {
     return RenderIndexedStack(
       index: index,
       alignment: alignment,
-      textDirection: textDirection ?? Directionality.of(context),
+      textDirection: textDirection ?? Directionality.maybeOf(context),
     );
   }
 
@@ -3471,7 +3488,7 @@ class IndexedStack extends Stack {
     renderObject
       ..index = index
       ..alignment = alignment
-      ..textDirection = textDirection ?? Directionality.of(context);
+      ..textDirection = textDirection ?? Directionality.maybeOf(context);
   }
 }
 
@@ -4084,7 +4101,7 @@ class Flex extends MultiChildRenderObjectWidget {
   /// the logic for providing a text direction only when it is necessary.
   @protected
   TextDirection? getEffectiveTextDirection(BuildContext context) {
-    return textDirection ?? (_needTextDirection ? Directionality.of(context) : null);
+    return textDirection ?? (_needTextDirection ? Directionality.maybeOf(context) : null);
   }
 
   @override
@@ -4954,7 +4971,7 @@ class Wrap extends MultiChildRenderObjectWidget {
       runAlignment: runAlignment,
       runSpacing: runSpacing,
       crossAxisAlignment: crossAxisAlignment,
-      textDirection: textDirection ?? Directionality.of(context),
+      textDirection: textDirection ?? Directionality.maybeOf(context),
       verticalDirection: verticalDirection,
       clipBehavior: clipBehavior,
     );
@@ -4969,7 +4986,7 @@ class Wrap extends MultiChildRenderObjectWidget {
       ..runAlignment = runAlignment
       ..runSpacing = runSpacing
       ..crossAxisAlignment = crossAxisAlignment
-      ..textDirection = textDirection ?? Directionality.of(context)
+      ..textDirection = textDirection ?? Directionality.maybeOf(context)
       ..verticalDirection = verticalDirection
       ..clipBehavior = clipBehavior;
   }
@@ -6879,7 +6896,7 @@ class Semantics extends SingleChildRenderObjectWidget {
     if (!containsText)
       return null;
 
-    return Directionality.of(context);
+    return Directionality.maybeOf(context);
   }
 
   @override

packages/flutter/lib/src/widgets/container.dart

@@ -406,7 +406,7 @@ class Container extends StatelessWidget {
       assert(decoration != null);
       current = ClipPath(
         clipper: _DecorationClipper(
-          textDirection: Directionality.of(context),
+          textDirection: Directionality.maybeOf(context),
           decoration: decoration!,
         ),
         clipBehavior: clipBehavior,

packages/flutter/lib/src/widgets/image.dart

@@ -52,7 +52,7 @@ ImageConfiguration createLocalImageConfiguration(BuildContext context, { Size? s
     bundle: DefaultAssetBundle.of(context),
     devicePixelRatio: MediaQuery.of(context, nullOk: true)?.devicePixelRatio ?? 1.0,
     locale: Localizations.localeOf(context, nullOk: true),
-    textDirection: Directionality.of(context),
+    textDirection: Directionality.maybeOf(context),
     size: size,
     platform: defaultTargetPlatform,
   );

packages/flutter/test/widgets/directionality_test.dart

@@ -55,11 +55,29 @@ void main() {
     bool good = false;
     await tester.pumpWidget(Builder(
       builder: (BuildContext context) {
-        expect(Directionality.of(context), isNull);
+        expect(Directionality.maybeOf(context), isNull);
         good = true;
         return const Placeholder();
       },
     ));
     expect(good, isTrue);
   });
+
+  testWidgets('Directionality.maybeOf', (WidgetTester tester) async {
+    final GlobalKey hasDirectionality = GlobalKey();
+    final GlobalKey noDirectionality = GlobalKey();
+    await tester.pumpWidget(
+      Container(
+        key: noDirectionality,
+        child: Directionality(
+          textDirection: TextDirection.rtl,
+          child: Container(
+            key: hasDirectionality,
+          ),
+        )
+      )
+    );
+    expect(Directionality.maybeOf(noDirectionality.currentContext!), isNull);
+    expect(Directionality.maybeOf(hasDirectionality.currentContext!), TextDirection.rtl);
+  });
 }