`CupertinoSlider`: Add clickable cursor for web (#99557)

packages/flutter/lib/src/cupertino/slider.dart

@@ -5,9 +5,10 @@
 import 'dart:math' as math;
 import 'dart:ui' show lerpDouble;
 
-import 'package:flutter/foundation.dart' show clampDouble;
+import 'package:flutter/foundation.dart';
 import 'package:flutter/gestures.dart';
 import 'package:flutter/rendering.dart';
+import 'package:flutter/services.dart';
 import 'package:flutter/widgets.dart';
 
 import 'colors.dart';
@@ -294,6 +295,7 @@ class _CupertinoSliderRenderObjectWidget extends LeafRenderObjectWidget {
       onChangeEnd: onChangeEnd,
       vsync: vsync,
       textDirection: Directionality.of(context),
+      cursor: kIsWeb ? SystemMouseCursors.click : MouseCursor.defer,
     );
   }
 
@@ -322,7 +324,7 @@ const Duration _kDiscreteTransitionDuration = Duration(milliseconds: 500);
 
 const double _kAdjustmentUnit = 0.1; // Matches iOS implementation of material slider.
 
-class _RenderCupertinoSlider extends RenderConstrainedBox {
+class _RenderCupertinoSlider extends RenderConstrainedBox implements MouseTrackerAnnotation {
   _RenderCupertinoSlider({
     required double value,
     int? divisions,
@@ -334,8 +336,11 @@ class _RenderCupertinoSlider extends RenderConstrainedBox {
     this.onChangeEnd,
     required TickerProvider vsync,
     required TextDirection textDirection,
+    MouseCursor cursor = MouseCursor.defer,
   }) : assert(value != null && value >= 0.0 && value <= 1.0),
        assert(textDirection != null),
+       assert(cursor != null),
+       _cursor = cursor,
        _value = value,
        _divisions = divisions,
        _activeColor = activeColor,
@@ -584,4 +589,27 @@ class _RenderCupertinoSlider extends RenderConstrainedBox {
       onChanged!(clampDouble(value - _semanticActionUnit, 0.0, 1.0));
     }
   }
+
+  @override
+  MouseCursor get cursor => _cursor;
+  MouseCursor _cursor;
+  set cursor(MouseCursor value) {
+    if (_cursor != value) {
+      _cursor = value;
+      // A repaint is needed in order to trigger a device update of
+      // [MouseTracker] so that this new value can be found.
+      markNeedsPaint();
+    }
+  }
+
+  @override
+  PointerEnterEventListener? onEnter;
+
+  PointerHoverEventListener? onHover;
+
+  @override
+  PointerExitEventListener? onExit;
+
+  @override
+  bool get validForMouseTracker => false;
 }

packages/flutter/test/cupertino/slider_test.dart

@@ -3,6 +3,8 @@
 // found in the LICENSE file.
 
 import 'package:flutter/cupertino.dart';
+import 'package:flutter/foundation.dart';
+import 'package:flutter/gestures.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/scheduler.dart';
@@ -613,4 +615,46 @@ void main() {
           ..rrect(color: CupertinoColors.activeOrange.color),
     );
   });
+
+  testWidgets('Hovering over Cupertino slider thumb updates cursor to clickable on Web', (WidgetTester tester) async {
+    final Key sliderKey = UniqueKey();
+    double value = 0.0;
+
+    await tester.pumpWidget(
+      CupertinoApp(
+        home: Directionality(
+          textDirection: TextDirection.ltr,
+          child: StatefulBuilder(
+            builder: (BuildContext context, StateSetter setState) {
+              return Material(
+                child: Center(
+                  child: CupertinoSlider(
+                    key: sliderKey,
+                    value: value,
+                    onChanged: (double newValue) {
+                      setState(() { value = newValue; });
+                    },
+                  ),
+                ),
+              );
+            },
+          ),
+        ),
+      ),
+    );
+
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse, pointer: 1);
+    await gesture.addPointer(location: const Offset(10, 10));
+    await tester.pumpAndSettle();
+    expect(RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1), SystemMouseCursors.basic);
+
+    final Offset topLeft = tester.getTopLeft(find.byKey(sliderKey));
+    await gesture.moveTo(topLeft + const Offset(15, 0));
+    addTearDown(gesture.removePointer);
+    await tester.pumpAndSettle();
+    expect(
+      RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1),
+      kIsWeb ? SystemMouseCursors.click : SystemMouseCursors.basic,
+    );
+  });
 }