Add splashBorderRadius to TabBar (#97204)

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

@@ -644,6 +644,7 @@ class TabBar extends StatefulWidget implements PreferredSizeWidget {
     this.onTap,
     this.physics,
     this.splashFactory,
+    this.splashBorderRadius,
   }) : assert(tabs != null),
        assert(isScrollable != null),
        assert(dragStartBehavior != null),
@@ -720,6 +721,11 @@ class TabBar extends StatefulWidget implements PreferredSizeWidget {
   /// occupied by the tab in the tab bar. If [indicatorSize] is
   /// [TabBarIndicatorSize.label], then the tab's bounds are only as wide as
   /// the tab widget itself.
+  ///
+  /// See also:
+  ///
+  ///  * [splashBorderRadius], which defines the clipping radius of the splash
+  ///    and is generally used with [BoxDecoration.borderRadius].
   final Decoration? indicator;
 
   /// Whether this tab bar should automatically adjust the [indicatorColor].
@@ -849,6 +855,22 @@ class TabBar extends StatefulWidget implements PreferredSizeWidget {
   /// ```
   final InteractiveInkFeatureFactory? splashFactory;
 
+  /// Defines the clipping radius of splashes that extend outside the bounds of the tab.
+  ///
+  /// This can be useful to match the [BoxDecoration.borderRadius] provided as [indicator].
+  /// ```dart
+  /// TabBar(
+  ///   indicator: BoxDecoration(
+  ///     borderRadius: BorderRadius.circular(40),
+  ///   ),
+  ///   splashBorderRadius: BorderRadius.circular(40),
+  ///   ...
+  /// )
+  /// ```
+  ///
+  /// If this property is null, it is interpreted as [BorderRadius.zero].
+  final BorderRadius? splashBorderRadius;
+
   /// A size whose height depends on if the tabs have both icons and text.
   ///
   /// [AppBar] uses this size to compute its own preferred size.
@@ -1206,6 +1228,7 @@ class _TabBarState extends State<TabBar> {
         enableFeedback: widget.enableFeedback ?? true,
         overlayColor: widget.overlayColor ?? tabBarTheme.overlayColor,
         splashFactory: widget.splashFactory ?? tabBarTheme.splashFactory,
+        borderRadius: widget.splashBorderRadius,
         child: Padding(
           padding: EdgeInsets.only(bottom: widget.indicatorWeight),
           child: Stack(

packages/flutter/test/material/tabs_test.dart

@@ -4378,6 +4378,50 @@ void main() {
     expect(tester.widget<InkWell>(find.byType(InkWell)).splashFactory, splashFactory);
     expect(tester.widget<InkWell>(find.byType(InkWell)).overlayColor, overlayColor);
   });
+
+  testWidgets('splashBorderRadius is passed to InkWell.borderRadius', (WidgetTester tester) async {
+    const Color hoverColor = Color(0xfff44336);
+    const double radius = 20;
+    await tester.pumpWidget(
+      boilerplate(
+        child: DefaultTabController(
+          length: 1,
+          child: TabBar(
+            overlayColor: MaterialStateProperty.resolveWith<Color>(
+              (Set<MaterialState> states) {
+                if (states.contains(MaterialState.hovered)) {
+                  return hoverColor;
+                }
+                return Colors.black54;
+              },
+            ),
+            splashBorderRadius: BorderRadius.circular(radius),
+            tabs: const <Widget>[
+              Tab(
+                child: Text(''),
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+    await tester.pumpAndSettle();
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse, pointer: 1);
+    await gesture.moveTo(tester.getCenter(find.byType(Tab)));
+    await tester.pumpAndSettle();
+    final RenderObject object = tester.allRenderObjects.firstWhere((RenderObject element) => element.runtimeType.toString() == '_RenderInkFeatures');
+    expect(
+      object,
+      paints..rrect(
+        color: hoverColor,
+        rrect: RRect.fromRectAndRadius(
+          tester.getRect(find.byType(InkWell)),
+          const Radius.circular(radius)
+        ),
+      ),
+    );
+    gesture.removePointer();
+  });
 }
 
 class KeepAliveInk extends StatefulWidget {