#163840 - CupertinoButton cursor doesn't change to clickable on desktop (#164196)

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This PR addresses Issue number: 163840, where when hovering over a
Cupertino button the mouse cursor wouldn't switch to clickable and there
wasn't any option to configure it.

Adds Mouse cursor to CupertinoButton, CupertinoButton.Filled and
CupertinoButton.Tinted

Fixes https://github.com/flutter/flutter/issues/163840
Part of https://github.com/flutter/flutter/issues/58192

Demo of the changes


https://github.com/user-attachments/assets/2e5d874e-cdfe-44bf-9710-bbbde99be3f7

Code snippet showing new behavior

```dart
import 'package:flutter/cupertino.dart';

void main() => runApp(
  // const Center(child: Text('Hello, world!', key: Key('title'), textDirection: TextDirection.ltr)),
  CupertinoApp(
    theme: const CupertinoThemeData(
      brightness: Brightness.light,
    ),
    home: Center(
      child: Column(
        spacing: 5.0,
        mainAxisAlignment: MainAxisAlignment.center,
        crossAxisAlignment: CrossAxisAlignment.center,
        children: <Widget>[
          CupertinoButton(
            onPressed: (){},
            child: const Text('Default Cursor'),
          ),
          CupertinoButton(
            onPressed: (){},
            mouseCursor: SystemMouseCursors.grab,
            child: const Text('Custom Cursor'),
          ),
          CupertinoButton.filled(
            onPressed: (){},
            mouseCursor: SystemMouseCursors.copy,
            child: const Text('Custom Cursor 2'),
          ),
          CupertinoButton.tinted(
            onPressed: (){},
            mouseCursor: SystemMouseCursors.help,
            child: const Text('Custom Cursor 2'),
          ),
        ],
      )
    ),
  ),
);
```


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---------

Co-authored-by: Tong Mu <dkwingsmt@users.noreply.github.com>
Co-authored-by: Tirth <pateltirth454@gmail.com>
Co-authored-by: Victor Sanni <victorsanniay@gmail.com>

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

@@ -90,6 +90,7 @@ class CupertinoButton extends StatefulWidget {
     this.focusNode,
     this.onFocusChange,
     this.autofocus = false,
+    this.mouseCursor,
     this.onLongPress,
     required this.onPressed,
   }) : assert(pressedOpacity == null || (pressedOpacity >= 0.0 && pressedOpacity <= 1.0)),
@@ -125,6 +126,7 @@ class CupertinoButton extends StatefulWidget {
     this.focusNode,
     this.onFocusChange,
     this.autofocus = false,
+    this.mouseCursor,
     this.onLongPress,
     required this.onPressed,
   }) : assert(minimumSize == null || minSize == null),
@@ -154,6 +156,7 @@ class CupertinoButton extends StatefulWidget {
     this.focusNode,
     this.onFocusChange,
     this.autofocus = false,
+    this.mouseCursor,
     this.onLongPress,
     required this.onPressed,
   }) : assert(pressedOpacity == null || (pressedOpacity >= 0.0 && pressedOpacity <= 1.0)),
@@ -258,6 +261,23 @@ class CupertinoButton extends StatefulWidget {
   /// {@macro flutter.widgets.Focus.autofocus}
   final bool autofocus;
 
+  /// The cursor for a mouse pointer when it enters or is hovering over the widget.
+  ///
+  /// If [mouseCursor] is a [WidgetStateMouseCursor],
+  /// [WidgetStateProperty.resolve] is used for the following [WidgetState]:
+  ///  * [WidgetState.disabled].
+  ///
+  /// If null, then [MouseCursor.defer] is used when the button is disabled.
+  /// When the button is enabled, [SystemMouseCursors.click] is used on Web
+  /// and [MouseCursor.defer] is used on other platforms.
+  ///
+  /// See also:
+  ///
+  ///  * [WidgetStateMouseCursor], a [MouseCursor] that implements
+  ///    [WidgetStateProperty] which is used in APIs that need to accept
+  ///    either a [MouseCursor] or a [WidgetStateProperty].
+  final MouseCursor? mouseCursor;
+
   final _CupertinoButtonStyle _style;
 
   /// Whether the button is enabled or disabled. Buttons are disabled by default. To
@@ -297,6 +317,13 @@ class _CupertinoButtonState extends State<CupertinoButton> with SingleTickerProv
 
   late bool isFocused;
 
+  static final WidgetStateProperty<MouseCursor> _defaultCursor =
+      WidgetStateProperty.resolveWith<MouseCursor>((Set<WidgetState> states) {
+        return !states.contains(WidgetState.disabled) && kIsWeb
+            ? SystemMouseCursors.click
+            : MouseCursor.defer;
+      });
+
   @override
   void initState() {
     super.initState();
@@ -459,9 +486,16 @@ class _CupertinoButtonState extends State<CupertinoButton> with SingleTickerProv
       size:
           textStyle.fontSize != null ? textStyle.fontSize! * 1.2 : kCupertinoButtonDefaultIconSize,
     );
+
     final DeviceGestureSettings? gestureSettings = MediaQuery.maybeGestureSettingsOf(context);
+
+    final Set<WidgetState> states = <WidgetState>{if (!enabled) WidgetState.disabled};
+    final MouseCursor effectiveMouseCursor =
+        WidgetStateProperty.resolveAs<MouseCursor?>(widget.mouseCursor, states) ??
+        _defaultCursor.resolve(states);
+
     return MouseRegion(
-      cursor: enabled && kIsWeb ? SystemMouseCursors.click : MouseCursor.defer,
+      cursor: effectiveMouseCursor,
       child: FocusableActionDetector(
         actions: _actionMap,
         focusNode: widget.focusNode,

packages/flutter/test/cupertino/button_test.dart

@@ -941,8 +941,63 @@ void main() {
     await gesture.up();
     expect(value, isTrue);
   });
+
+  testWidgets('Mouse cursor resolves in enabled/disabled states', (WidgetTester tester) async {
+    Widget buildButton({required bool enabled, MouseCursor? cursor}) {
+      return CupertinoApp(
+        home: Center(
+          child: CupertinoButton(
+            onPressed: enabled ? () {} : null,
+            mouseCursor: cursor,
+            child: const Text('Tap Me'),
+          ),
+        ),
+      );
+    }
+
+    // Test default mouse cursor
+    final TestGesture gesture = await tester.createGesture(
+      kind: PointerDeviceKind.mouse,
+      pointer: 1,
+    );
+    await tester.pumpWidget(buildButton(enabled: true, cursor: const _ButtonMouseCursor()));
+    await gesture.addPointer(location: tester.getCenter(find.byType(CupertinoButton)));
+    await tester.pump();
+    await gesture.moveTo(tester.getCenter(find.byType(CupertinoButton)));
+    expect(
+      RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1),
+      SystemMouseCursors.basic,
+    );
+    await gesture.removePointer();
+
+    // Test disabled state mouse cursor
+    await tester.pumpWidget(buildButton(enabled: false, cursor: const _ButtonMouseCursor()));
+    await gesture.addPointer(location: tester.getCenter(find.byType(CupertinoButton)));
+    await tester.pump();
+    await gesture.moveTo(tester.getCenter(find.byType(CupertinoButton)));
+    expect(
+      RendererBinding.instance.mouseTracker.debugDeviceActiveCursor(1),
+      SystemMouseCursors.forbidden,
+    );
+    await gesture.removePointer();
+  });
 }
 
 Widget boilerplate({required Widget child}) {
   return Directionality(textDirection: TextDirection.ltr, child: Center(child: child));
 }
+
+class _ButtonMouseCursor extends WidgetStateMouseCursor {
+  const _ButtonMouseCursor();
+
+  @override
+  MouseCursor resolve(Set<WidgetState> states) {
+    if (states.contains(WidgetState.disabled)) {
+      return SystemMouseCursors.forbidden;
+    }
+    return SystemMouseCursors.basic;
+  }
+
+  @override
+  String get debugDescription => '_ButtonMouseCursor()';
+}