Update Material 3 bottom sheet (#122445)

* M3 bottomsheet

* Update bottom_sheet.dart

* Update bottom_sheet.dart

* Update bottom_sheet.dart

* Update bottom_sheet.dart

* Update bottom_sheet.dart

* Update bottom_sheet.dart

* Update bottom_sheet.dart

* Update bottom_sheet.dart

* Update bottom_sheet.dart

* Update bottom_sheet.dart

* Update packages/flutter/lib/src/material/bottom_sheet.dart

Co-authored-by: Pierre-Louis <6655696+guidezpl@users.noreply.github.com>

* Update packages/flutter/lib/src/material/bottom_sheet.dart

Co-authored-by: Pierre-Louis <6655696+guidezpl@users.noreply.github.com>

* Update packages/flutter/lib/src/material/bottom_sheet.dart

Co-authored-by: Pierre-Louis <6655696+guidezpl@users.noreply.github.com>

* Update packages/flutter/lib/src/material/bottom_sheet.dart

Co-authored-by: Pierre-Louis <6655696+guidezpl@users.noreply.github.com>

* Update packages/flutter/lib/src/material/bottom_sheet.dart

Co-authored-by: Pierre-Louis <6655696+guidezpl@users.noreply.github.com>

* Update packages/flutter/lib/src/material/bottom_sheet.dart

Co-authored-by: Pierre-Louis <6655696+guidezpl@users.noreply.github.com>

* Update bottom_sheet.dart

Update bottom_sheet_test.dart

Update bottom_sheet.dart

* showDragHandle defaults to false

* fix test

---------

Co-authored-by: Pierre-Louis <6655696+guidezpl@users.noreply.github.com>

dev/tools/gen_defaults/lib/bottom_sheet_template.dart

@@ -17,6 +17,7 @@ class _${blockName}DefaultsM3 extends BottomSheetThemeData {
       elevation: ${elevation("md.comp.sheet.bottom.docked.standard.container")},
       modalElevation: ${elevation("md.comp.sheet.bottom.docked.modal.container")},
       shape: ${shape("md.comp.sheet.bottom.docked.container")},
+      constraints: const BoxConstraints(maxWidth: 640),
     );
 
   final BuildContext context;
@@ -30,6 +31,12 @@ class _${blockName}DefaultsM3 extends BottomSheetThemeData {
 
   @override
   Color? get shadowColor => Colors.transparent;
+
+  @override
+  Color? get dragHandleColor => ${componentColor("md.comp.sheet.bottom.docked.drag-handle")};
+
+  @override
+  Size? get dragHandleSize => ${size("md.comp.sheet.bottom.docked.drag-handle")};
 }
 ''';
 }

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

@@ -5,16 +5,19 @@
 import 'dart:ui' show lerpDouble;
 
 import 'package:flutter/foundation.dart';
+import 'package:flutter/gestures.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';
 
 import 'bottom_sheet_theme.dart';
 import 'color_scheme.dart';
 import 'colors.dart';
+import 'constants.dart';
 import 'curves.dart';
 import 'debug.dart';
 import 'material.dart';
 import 'material_localizations.dart';
+import 'material_state.dart';
 import 'scaffold.dart';
 import 'theme.dart';
 
@@ -65,7 +68,8 @@ typedef BottomSheetDragEndHandler = void Function(
 ///    sheet.
 ///  * [BottomSheetThemeData], which can be used to customize the default
 ///    bottom sheet property values.
-///  * <https://material.io/design/components/sheets-bottom.html>
+///  * The Material 2 spec at <https://m2.material.io/components/sheets-bottom>.
+///  * The Material 3 spec at <https://m3.material.io/components/bottom-sheets/overview>.
 class BottomSheet extends StatefulWidget {
   /// Creates a bottom sheet.
   ///
@@ -76,6 +80,9 @@ class BottomSheet extends StatefulWidget {
     super.key,
     this.animationController,
     this.enableDrag = true,
+    this.showDragHandle,
+    this.dragHandleColor,
+    this.dragHandleSize,
     this.onDragStart,
     this.onDragEnd,
     this.backgroundColor,
@@ -111,9 +118,34 @@ class BottomSheet extends StatefulWidget {
   /// If true, the bottom sheet can be dragged up and down and dismissed by
   /// swiping downwards.
   ///
+  /// If [showDragHandle] is true, this only applies to the content below the drag handle,
+  /// because the drag handle is always draggable.
+  ///
   /// Default is true.
   final bool enableDrag;
 
+  /// Specifies whether a drag handle is shown.
+  ///
+  /// The drag handle appears at the top of the bottom sheet. The default color is
+  /// [ColorScheme.onSurfaceVariant] with an opacity of 0.4 and can be customized
+  /// using [dragHandleColor]. The default size is `Size(32,4)` and can be customized
+  /// with [dragHandleSize].
+  ///
+  /// If null, then the value of  [BottomSheetThemeData.showDragHandle] is used. If
+  /// that is also null, defaults to false.
+  final bool? showDragHandle;
+
+  /// The bottom sheet drag handle's color.
+  ///
+  /// Defaults to [BottomSheetThemeData.dragHandleColor].
+  /// If that is also null, defaults to [ColorScheme.onSurfaceVariant]
+  /// with an opacity of 0.4.
+  final Color? dragHandleColor;
+
+  /// Defaults to [BottomSheetThemeData.dragHandleSize].
+  /// If that is also null, defaults to Size(32, 4).
+  final Size? dragHandleSize;
+
   /// Called when the user begins dragging the bottom sheet vertically, if
   /// [enableDrag] is true.
   ///
@@ -222,14 +254,19 @@ class _BottomSheetState extends State<BottomSheet> {
 
   bool get _dismissUnderway => widget.animationController!.status == AnimationStatus.reverse;
 
+  Set<MaterialState> dragHandleMaterialState = <MaterialState>{};
+
   void _handleDragStart(DragStartDetails details) {
+    setState(() {
+      dragHandleMaterialState.add(MaterialState.dragged);
+    });
     widget.onDragStart?.call(details);
   }
 
   void _handleDragUpdate(DragUpdateDetails details) {
     assert(
-      widget.enableDrag && widget.animationController != null,
+      (widget.enableDrag || (widget.showDragHandle?? false)) && widget.animationController != null,
-      "'BottomSheet.animationController' can not be null when 'BottomSheet.enableDrag' is true. "
+      "'BottomSheet.animationController' cannot be null when 'BottomSheet.enableDrag' or 'BottomSheet.showDragHandle' is true. "
       "Use 'BottomSheet.createAnimationController' to create one, or provide another AnimationController.",
     );
     if (_dismissUnderway) {
@@ -240,13 +277,16 @@ class _BottomSheetState extends State<BottomSheet> {
 
   void _handleDragEnd(DragEndDetails details) {
     assert(
-      widget.enableDrag && widget.animationController != null,
+      (widget.enableDrag || (widget.showDragHandle?? false)) && widget.animationController != null,
-      "'BottomSheet.animationController' can not be null when 'BottomSheet.enableDrag' is true. "
+      "'BottomSheet.animationController' cannot be null when 'BottomSheet.enableDrag' or 'BottomSheet.showDragHandle' is true. "
       "Use 'BottomSheet.createAnimationController' to create one, or provide another AnimationController.",
     );
     if (_dismissUnderway) {
       return;
     }
+    setState(() {
+      dragHandleMaterialState.remove(MaterialState.dragged);
+    });
     bool isClosing = false;
     if (details.velocity.pixelsPerSecond.dy > _minFlingVelocity) {
       final double flingVelocity = -details.velocity.pixelsPerSecond.dy / _childHeight;
@@ -282,17 +322,55 @@ class _BottomSheetState extends State<BottomSheet> {
     return false;
   }
 
+  void _handleDragHandleHover(bool hovering) {
+    if (hovering != dragHandleMaterialState.contains(MaterialState.hovered)) {
+      setState(() {
+        if(hovering){
+          dragHandleMaterialState.add(MaterialState.hovered);
+        }
+        else{
+          dragHandleMaterialState.remove(MaterialState.hovered);
+        }
+      });
+    }
+  }
+
   @override
   Widget build(BuildContext context) {
     final BottomSheetThemeData bottomSheetTheme = Theme.of(context).bottomSheetTheme;
-    final BottomSheetThemeData defaults = Theme.of(context).useMaterial3 ? _BottomSheetDefaultsM3(context) : const BottomSheetThemeData();
+    final bool useMaterial3 = Theme.of(context).useMaterial3;
-    final BoxConstraints? constraints = widget.constraints ?? bottomSheetTheme.constraints;
+    final BottomSheetThemeData defaults = useMaterial3 ? _BottomSheetDefaultsM3(context) : const BottomSheetThemeData();
+    final BoxConstraints? constraints = widget.constraints ?? bottomSheetTheme.constraints ?? defaults.constraints;
     final Color? color = widget.backgroundColor ?? bottomSheetTheme.backgroundColor ?? defaults.backgroundColor;
     final Color? surfaceTintColor = bottomSheetTheme.surfaceTintColor ?? defaults.surfaceTintColor;
     final Color? shadowColor = widget.shadowColor ?? bottomSheetTheme.shadowColor ?? defaults.shadowColor;
     final double elevation = widget.elevation ?? bottomSheetTheme.elevation ?? defaults.elevation ?? 0;
     final ShapeBorder? shape = widget.shape ?? bottomSheetTheme.shape ?? defaults.shape;
     final Clip clipBehavior = widget.clipBehavior ?? bottomSheetTheme.clipBehavior ?? Clip.none;
+    final bool showDragHandle = widget.showDragHandle ?? (widget.enableDrag && (bottomSheetTheme.showDragHandle ?? false));
+
+    Widget? dragHandle;
+    if (showDragHandle){
+      dragHandle = _DragHandle(
+        onSemanticsTap: widget.onClosing,
+        handleHover: _handleDragHandleHover,
+        materialState: dragHandleMaterialState,
+        dragHandleColor: widget.dragHandleColor,
+        dragHandleSize: widget.dragHandleSize,
+      );
+      // Only add [GestureDetector] to the drag handle when the rest of the
+      // bottom sheet is not draggable. If the whole bottom sheet is draggable,
+      // no need to add it.
+      if(!widget.enableDrag) {
+        dragHandle = GestureDetector(
+          onVerticalDragStart: _handleDragStart,
+          onVerticalDragUpdate: _handleDragUpdate,
+          onVerticalDragEnd: _handleDragEnd,
+          excludeFromSemantics: true,
+          child: dragHandle,
+        );
+      }
+    }
 
     Widget bottomSheet = Material(
       key: _childKey,
@@ -304,7 +382,18 @@ class _BottomSheetState extends State<BottomSheet> {
       clipBehavior: clipBehavior,
       child: NotificationListener<DraggableScrollableNotification>(
         onNotification: extentChanged,
-        child: widget.builder(context),
+        child: !showDragHandle
+          ? widget.builder(context)
+          : Stack(
+              alignment: Alignment.topCenter,
+              children: <Widget>[
+                dragHandle!,
+                Padding(
+                  padding: const EdgeInsets.only(top: kMinInteractiveDimension),
+                  child: widget.builder(context),
+                ),
+              ],
+            ),
       ),
     );
 
@@ -335,6 +424,55 @@ class _BottomSheetState extends State<BottomSheet> {
 
 typedef _SizeChangeCallback<Size> = void Function(Size);
 
+class _DragHandle extends StatelessWidget {
+  const _DragHandle({
+    required this.onSemanticsTap,
+    required this.handleHover,
+    required this.materialState,
+    this.dragHandleColor,
+    this.dragHandleSize,
+  });
+
+  final VoidCallback? onSemanticsTap;
+  final Function(bool) handleHover;
+  final Set<MaterialState> materialState;
+  final Color? dragHandleColor;
+  final Size? dragHandleSize;
+
+  @override
+  Widget build(BuildContext context) {
+    final BottomSheetThemeData bottomSheetTheme = Theme.of(context).bottomSheetTheme;
+    final BottomSheetThemeData m3Defaults = _BottomSheetDefaultsM3(context);
+    final Size handleSize = dragHandleSize ?? bottomSheetTheme.dragHandleSize ?? m3Defaults.dragHandleSize!;
+
+    return MouseRegion(
+      onEnter: (PointerEnterEvent event) => handleHover(true),
+      onExit: (PointerExitEvent event) => handleHover(false),
+      child: Semantics(
+        label: MaterialLocalizations.of(context).modalBarrierDismissLabel,
+        container: true,
+        onTap: onSemanticsTap,
+        child: SizedBox(
+          height: kMinInteractiveDimension,
+          width: kMinInteractiveDimension,
+          child: Center(
+            child: Container(
+              height: handleSize.height,
+              width: handleSize.width,
+              decoration: BoxDecoration(
+                borderRadius: BorderRadius.circular(handleSize.height/2),
+                color: MaterialStateProperty.resolveAs<Color?>(dragHandleColor, materialState)
+                  ?? MaterialStateProperty.resolveAs<Color?>(bottomSheetTheme.dragHandleColor, materialState)
+                  ?? m3Defaults.dragHandleColor,
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+}
+
 class _BottomSheetLayoutWithSizeListener extends SingleChildRenderObjectWidget {
 
   const _BottomSheetLayoutWithSizeListener({
@@ -500,6 +638,7 @@ class _ModalBottomSheet<T> extends StatefulWidget {
     this.constraints,
     this.isScrollControlled = false,
     this.enableDrag = true,
+    this.showDragHandle = false,
   });
 
   final ModalBottomSheetRoute<T> route;
@@ -510,6 +649,7 @@ class _ModalBottomSheet<T> extends StatefulWidget {
   final Clip? clipBehavior;
   final BoxConstraints? constraints;
   final bool enableDrag;
+  final bool showDragHandle;
 
   @override
   _ModalBottomSheetState<T> createState() => _ModalBottomSheetState<T>();
@@ -571,6 +711,7 @@ class _ModalBottomSheetState<T> extends State<_ModalBottomSheet<T>> {
         clipBehavior: widget.clipBehavior,
         constraints: widget.constraints,
         enableDrag: widget.enableDrag,
+        showDragHandle: widget.showDragHandle,
         onDragStart: handleDragStart,
         onDragEnd: handleDragEnd,
       ),
@@ -658,7 +799,8 @@ class _ModalBottomSheetState<T> extends State<_ModalBottomSheet<T>> {
 ///    and then becomes scrollable once it reaches its maximum size.
 ///  * [DisplayFeatureSubScreen], which documents the specifics of how
 ///    [DisplayFeature]s can split the screen into sub-screens.
-///  * <https://material.io/design/components/sheets-bottom.html#modal-bottom-sheet>
+///  * The Material 2 spec at <https://m2.material.io/components/sheets-bottom>.
+///  * The Material 3 spec at <https://m3.material.io/components/bottom-sheets/overview>.
 class ModalBottomSheetRoute<T> extends PopupRoute<T> {
   /// A modal bottom sheet route.
   ModalBottomSheetRoute({
@@ -674,6 +816,7 @@ class ModalBottomSheetRoute<T> extends PopupRoute<T> {
     this.modalBarrierColor,
     this.isDismissible = true,
     this.enableDrag = true,
+    this.showDragHandle,
     required this.isScrollControlled,
     super.settings,
     this.transitionAnimationController,
@@ -773,9 +916,22 @@ class ModalBottomSheetRoute<T> extends PopupRoute<T> {
   /// If true, the bottom sheet can be dragged up and down and dismissed by
   /// swiping downwards.
   ///
+  /// This applies to the content below the drag handle, if showDragHandle is true.
+  ///
   /// Defaults is true.
   final bool enableDrag;
 
+  /// Specifies whether a drag handle is shown.
+  ///
+  /// The drag handle appears at the top of the bottom sheet. The default color is
+  /// [ColorScheme.onSurfaceVariant] with an opacity of 0.4 and can be customized
+  /// using dragHandleColor. The default size is `Size(32,4)` and can be customized
+  /// with dragHandleSize.
+  ///
+  /// If null, then the value of  [BottomSheetThemeData.showDragHandle] is used. If
+  /// that is also null, defaults to false.
+  final bool? showDragHandle;
+
   /// The animation controller that controls the bottom sheet's entrance and
   /// exit animations.
   ///
@@ -875,6 +1031,7 @@ class ModalBottomSheetRoute<T> extends PopupRoute<T> {
             constraints: constraints,
             isScrollControlled: isScrollControlled,
             enableDrag: enableDrag,
+            showDragHandle: showDragHandle ?? (enableDrag && (sheetTheme.showDragHandle ?? false)),
           );
         },
       ),
@@ -1023,7 +1180,8 @@ class _BottomSheetSuspendedCurve extends ParametricCurve<double> {
 ///    and then becomes scrollable once it reaches its maximum size.
 ///  * [DisplayFeatureSubScreen], which documents the specifics of how
 ///    [DisplayFeature]s can split the screen into sub-screens.
-///  * <https://material.io/design/components/sheets-bottom.html#modal-bottom-sheet>
+///  * The Material 2 spec at <https://m2.material.io/components/sheets-bottom>.
+///  * The Material 3 spec at <https://m3.material.io/components/bottom-sheets/overview>.
 Future<T?> showModalBottomSheet<T>({
   required BuildContext context,
   required WidgetBuilder builder,
@@ -1037,6 +1195,7 @@ Future<T?> showModalBottomSheet<T>({
   bool useRootNavigator = false,
   bool isDismissible = true,
   bool enableDrag = true,
+  bool? showDragHandle,
   bool useSafeArea = false,
   RouteSettings? routeSettings,
   AnimationController? transitionAnimationController,
@@ -1061,6 +1220,7 @@ Future<T?> showModalBottomSheet<T>({
     isDismissible: isDismissible,
     modalBarrierColor: barrierColor ?? Theme.of(context).bottomSheetTheme.modalBarrierColor,
     enableDrag: enableDrag,
+    showDragHandle: showDragHandle,
     settings: routeSettings,
     transitionAnimationController: transitionAnimationController,
     anchorPoint: anchorPoint,
@@ -1111,7 +1271,8 @@ Future<T?> showModalBottomSheet<T>({
 ///  * [showModalBottomSheet], which can be used to display a modal bottom
 ///    sheet.
 ///  * [Scaffold.of], for information about how to obtain the [BuildContext].
-///  * <https://material.io/design/components/sheets-bottom.html#standard-bottom-sheet>
+///  * The Material 2 spec at <https://m2.material.io/components/sheets-bottom>.
+///  * The Material 3 spec at <https://m3.material.io/components/bottom-sheets/overview>.
 PersistentBottomSheetController<T> showBottomSheet<T>({
   required BuildContext context,
   required WidgetBuilder builder,
@@ -1154,19 +1315,26 @@ class _BottomSheetDefaultsM3 extends BottomSheetThemeData {
       elevation: 1.0,
       modalElevation: 1.0,
       shape: const RoundedRectangleBorder(borderRadius: BorderRadius.vertical(top: Radius.circular(28.0))),
+      constraints: const BoxConstraints(maxWidth: 640),
     );
 
   final BuildContext context;
   late final ColorScheme _colors = Theme.of(context).colorScheme;
 
   @override
-  Color? get backgroundColor => _colors.surface;
+  Color get backgroundColor => _colors.surface;
 
   @override
-  Color? get surfaceTintColor => _colors.surfaceTint;
+  Color get surfaceTintColor => _colors.surfaceTint;
 
   @override
-  Color? get shadowColor => Colors.transparent;
+  Color get shadowColor => Colors.transparent;
+
+  @override
+  Color get dragHandleColor => Theme.of(context).colorScheme.onSurfaceVariant.withOpacity(0.4);
+
+  @override
+  Size get dragHandleSize => const Size(32, 4);
 }
 
 // END GENERATED TOKEN PROPERTIES - BottomSheet

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

@@ -36,6 +36,9 @@ class BottomSheetThemeData with Diagnosticable {
     this.shadowColor,
     this.modalElevation,
     this.shape,
+    this.showDragHandle,
+    this.dragHandleColor,
+    this.dragHandleSize,
     this.clipBehavior,
     this.constraints,
   });
@@ -80,6 +83,15 @@ class BottomSheetThemeData with Diagnosticable {
   /// [BottomSheet] is rectangular.
   final ShapeBorder? shape;
 
+  /// Overrides the default value for [BottomSheet.showDragHandle].
+  final bool? showDragHandle;
+
+  /// Overrides the default value for [BottomSheet.dragHandleColor].
+  final Color? dragHandleColor;
+
+  /// Overrides the default value for [BottomSheet.dragHandleSize].
+  final Size? dragHandleSize;
+
   /// Overrides the default value for [BottomSheet.clipBehavior].
   ///
   /// If null, [BottomSheet] uses [Clip.none].
@@ -101,6 +113,9 @@ class BottomSheetThemeData with Diagnosticable {
     Color? shadowColor,
     double? modalElevation,
     ShapeBorder? shape,
+    bool? showDragHandle,
+    Color? dragHandleColor,
+    Size? dragHandleSize,
     Clip? clipBehavior,
     BoxConstraints? constraints,
   }) {
@@ -113,6 +128,9 @@ class BottomSheetThemeData with Diagnosticable {
       shadowColor: shadowColor ?? this.shadowColor,
       modalElevation: modalElevation ?? this.modalElevation,
       shape: shape ?? this.shape,
+      showDragHandle: showDragHandle ?? this.showDragHandle,
+      dragHandleColor: dragHandleColor ?? this.dragHandleColor,
+      dragHandleSize: dragHandleSize ?? this.dragHandleSize,
       clipBehavior: clipBehavior ?? this.clipBehavior,
       constraints: constraints ?? this.constraints,
     );
@@ -136,6 +154,9 @@ class BottomSheetThemeData with Diagnosticable {
       shadowColor: Color.lerp(a?.shadowColor, b?.shadowColor, t),
       modalElevation: lerpDouble(a?.modalElevation, b?.modalElevation, t),
       shape: ShapeBorder.lerp(a?.shape, b?.shape, t),
+      showDragHandle: t < 0.5 ? a?.showDragHandle : b?.showDragHandle,
+      dragHandleColor: Color.lerp(a?.dragHandleColor, b?.dragHandleColor, t),
+      dragHandleSize: Size.lerp(a?.dragHandleSize, b?.dragHandleSize, t),
       clipBehavior: t < 0.5 ? a?.clipBehavior : b?.clipBehavior,
       constraints: BoxConstraints.lerp(a?.constraints, b?.constraints, t),
     );
@@ -151,6 +172,9 @@ class BottomSheetThemeData with Diagnosticable {
     shadowColor,
     modalElevation,
     shape,
+    showDragHandle,
+    dragHandleColor,
+    dragHandleSize,
     clipBehavior,
     constraints,
   );
@@ -172,6 +196,9 @@ class BottomSheetThemeData with Diagnosticable {
         && other.modalBarrierColor == modalBarrierColor
         && other.modalElevation == modalElevation
         && other.shape == shape
+        && other.showDragHandle == showDragHandle
+        && other.dragHandleColor == dragHandleColor
+        && other.dragHandleSize == dragHandleSize
         && other.clipBehavior == clipBehavior
         && other.constraints == constraints;
   }
@@ -187,6 +214,9 @@ class BottomSheetThemeData with Diagnosticable {
     properties.add(ColorProperty('modalBarrierColor', modalBarrierColor, defaultValue: null));
     properties.add(DoubleProperty('modalElevation', modalElevation, defaultValue: null));
     properties.add(DiagnosticsProperty<ShapeBorder>('shape', shape, defaultValue: null));
+    properties.add(DiagnosticsProperty<bool>('showDragHandle', showDragHandle, defaultValue: null));
+    properties.add(ColorProperty('dragHandleColor', dragHandleColor, defaultValue: null));
+    properties.add(DiagnosticsProperty<Size>('dragHandleSize', dragHandleSize, defaultValue: null));
     properties.add(DiagnosticsProperty<Clip>('clipBehavior', clipBehavior, defaultValue: null));
     properties.add(DiagnosticsProperty<BoxConstraints>('constraints', constraints, defaultValue: null));
   }

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

@@ -2425,7 +2425,8 @@ class ScaffoldState extends State<Scaffold> with TickerProviderStateMixin, Resto
   ///  * [showModalBottomSheet], which can be used to display a modal bottom
   ///    sheet.
   ///  * [Scaffold.of], for information about how to obtain the [ScaffoldState].
-  ///  * <https://material.io/design/components/sheets-bottom.html#standard-bottom-sheet>
+  ///  * The Material 2 spec at <https://m2.material.io/components/sheets-bottom>.
+  ///  * The Material 3 spec at <https://m3.material.io/components/bottom-sheets/overview>.
   PersistentBottomSheetController<T> showBottomSheet<T>(
     WidgetBuilder builder, {
     Color? backgroundColor,

packages/flutter/test/material/bottom_sheet_test.dart

@@ -1008,6 +1008,138 @@ void main() {
     semantics.dispose();
   });
 
+  testWidgets('modal BottomSheet with drag handle has semantics', (WidgetTester tester) async {
+    final SemanticsTester semantics = SemanticsTester(tester);
+    final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
+
+    await tester.pumpWidget(MaterialApp(
+      theme: ThemeData.light(useMaterial3: true),
+      home: Scaffold(
+        key: scaffoldKey,
+        body: const Center(child: Text('body')),
+      ),
+    ));
+
+
+    showModalBottomSheet<void>(
+      context: scaffoldKey.currentContext!,
+      showDragHandle: true,
+      builder: (BuildContext context) {
+        return const Text('BottomSheet');
+      },
+    );
+
+    await tester.pump(); // bottom sheet show animation starts
+    await tester.pump(const Duration(seconds: 1)); // animation done
+
+    expect(semantics, hasSemantics(TestSemantics.root(
+      children: <TestSemantics>[
+        TestSemantics.rootChild(
+          children: <TestSemantics>[
+            TestSemantics(
+              children: <TestSemantics>[
+                TestSemantics(
+                  label: 'Dialog',
+                  textDirection: TextDirection.ltr,
+                  flags: <SemanticsFlag>[
+                    SemanticsFlag.scopesRoute,
+                    SemanticsFlag.namesRoute,
+                  ],
+                  children: <TestSemantics>[
+                    TestSemantics(
+                      label: 'BottomSheet',
+                      textDirection: TextDirection.ltr,
+                      children: <TestSemantics>[
+                        TestSemantics(
+                          actions: <SemanticsAction>[SemanticsAction.tap],
+                          label: 'Dismiss',
+                          textDirection: TextDirection.ltr,
+                        ),
+                      ],
+                    ),
+                  ],
+                ),
+              ],
+            ),
+            TestSemantics(
+              children: <TestSemantics>[
+                TestSemantics(
+                  actions: <SemanticsAction>[SemanticsAction.tap, SemanticsAction.dismiss],
+                  label: 'Scrim',
+                  textDirection: TextDirection.ltr,
+                ),
+              ],
+            ),
+          ],
+        ),
+      ],
+    ), ignoreTransform: true, ignoreRect: true, ignoreId: true));
+    semantics.dispose();
+  });
+
+  testWidgets('Drag handle color can take MaterialStateProperty', (WidgetTester tester) async {
+    final GlobalKey<ScaffoldState> scaffoldKey = GlobalKey<ScaffoldState>();
+    const Color defaultColor=Colors.blue;
+    const Color hoveringColor=Colors.green;
+
+    await tester.pumpWidget(MaterialApp(
+      theme: ThemeData.light(useMaterial3: true).copyWith(
+        bottomSheetTheme:  BottomSheetThemeData(
+          dragHandleColor: MaterialStateColor.resolveWith((Set<MaterialState> states) {
+            if (states.contains(MaterialState.hovered)) {
+              return hoveringColor;
+            }
+            return defaultColor;
+          }),
+        ),
+      ),
+      home: Scaffold(
+        key: scaffoldKey,
+        body: const Center(child: Text('body')),
+      ),
+    ));
+
+
+    showModalBottomSheet<void>(
+      context: scaffoldKey.currentContext!,
+      showDragHandle: true,
+      builder: (BuildContext context) {
+        return const Text('BottomSheet');
+      },
+    );
+
+    await tester.pump(); // bottom sheet show animation starts
+    await tester.pump(const Duration(seconds: 1)); // animation done
+
+    final Finder dragHandle = find.bySemanticsLabel('Dismiss');
+    expect(
+      tester.getSize(dragHandle),
+      const Size(48, 48),
+    );
+    final Offset center = tester.getCenter(dragHandle);
+    final Offset edge = tester.getTopLeft(dragHandle) - const Offset(1, 1);
+
+    // Shows default drag handle color
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse, pointer: 1);
+    await gesture.addPointer(location: edge);
+    await tester.pump();
+    BoxDecoration boxDecoration=tester.widget<Container>(find.descendant(
+      of: dragHandle,
+      matching: find.byWidgetPredicate((Widget widget) => widget is Container && widget.decoration != null),
+    )).decoration! as BoxDecoration;
+    expect(boxDecoration.color, defaultColor);
+
+    // Shows hovering drag handle color
+    await gesture.moveTo(center);
+    await tester.pump();
+    boxDecoration = tester.widget<Container>(find.descendant(
+     of: dragHandle,
+     matching: find.byWidgetPredicate((Widget widget) => widget is Container && widget.decoration != null),
+   )).decoration! as BoxDecoration;
+
+    expect(boxDecoration.color, hoveringColor);
+  });
+
   testWidgets('showModalBottomSheet does not use root Navigator by default', (WidgetTester tester) async {
     await tester.pumpWidget(MaterialApp(
       home: Scaffold(
@@ -1617,6 +1749,21 @@ void main() {
   });
 
   group('constraints', () {
+      testWidgets('default constraints are max width 640 in material 3', (WidgetTester tester) async {
+      await tester.pumpWidget(
+        MaterialApp(
+          theme: ThemeData.light(useMaterial3: true),
+          home: const MediaQuery(
+            data: MediaQueryData(size: Size(1000, 1000)),
+            child: Scaffold(
+              body: Center(child: Text('body')),
+              bottomSheet: Placeholder(fallbackWidth: 800),
+            ),
+          ),
+        ),
+      );
+      expect(tester.getSize(find.byType(Placeholder)).width, 640);
+    });
 
     testWidgets('No constraints by default for bottomSheet property', (WidgetTester tester) async {
       await tester.pumpWidget(const MaterialApp(

packages/flutter/test/material/bottom_sheet_theme_test.dart

@@ -32,6 +32,8 @@ void main() {
     expect(bottomSheetTheme.shape, null);
     expect(bottomSheetTheme.clipBehavior, null);
     expect(bottomSheetTheme.constraints, null);
+    expect(bottomSheetTheme.dragHandleColor, null);
+    expect(bottomSheetTheme.dragHandleSize, null);
   });
 
   testWidgets('Default BottomSheetThemeData debugFillProperties', (WidgetTester tester) async {
@@ -55,6 +57,8 @@ void main() {
       shape: RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(2.0))),
       clipBehavior: Clip.antiAlias,
       constraints: BoxConstraints(minWidth: 200, maxWidth: 640),
+      dragHandleColor: Color(0xFFFFFFFF),
+      dragHandleSize: Size(20, 20)
     ).debugFillProperties(builder);
 
     final List<String> description = builder.properties
@@ -67,6 +71,8 @@ void main() {
       'elevation: 2.0',
       'shadowColor: Color(0xff00ffff)',
       'shape: RoundedRectangleBorder(BorderSide(width: 0.0, style: none), BorderRadius.circular(2.0))',
+      'dragHandleColor: Color(0xffffffff)',
+      'dragHandleSize: Size(20.0, 20.0)',
       'clipBehavior: Clip.antiAlias',
       'constraints: BoxConstraints(200.0<=w<=640.0, 0.0<=h<=Infinity)',
     ]);