Feat: Add fillColor property for cupertinoCheckbox (#151761)

Feat: Add `fillColor` property for `CupertinoCheckbox`

Required for #151252

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

@@ -104,6 +104,7 @@ class CupertinoCheckbox extends StatefulWidget {
     required this.onChanged,
     this.activeColor,
     this.inactiveColor,
+    this.fillColor,
     this.checkColor,
     this.focusColor,
     this.focusNode,
@@ -152,11 +153,51 @@ class CupertinoCheckbox extends StatefulWidget {
 
   /// The color to use when this checkbox is checked.
   ///
+  /// If [fillColor] returns a non-null color in the [WidgetState.selected]
+  /// state, [fillColor] will be used instead of [activeColor].
+  ///
   /// Defaults to [CupertinoColors.activeBlue].
   final Color? activeColor;
 
+  /// {@template flutter.cupertino.CupertinoCheckbox.fillColor}
+  /// The color used to fill this checkbox.
+  ///
+  /// Resolves in the following states:
+  ///  * [WidgetState.selected].
+  ///  * [WidgetState.hovered].
+  ///  * [WidgetState.focused].
+  ///  * [WidgetState.disabled].
+  ///
+  /// {@tool snippet}
+  /// This example resolves the [fillColor] based on the current [WidgetState]
+  /// of the [CupertinoCheckbox], providing a different [Color] when it is
+  /// [WidgetState.disabled].
+  ///
+  /// ```dart
+  /// CupertinoCheckbox(
+  ///   value: true,
+  ///   onChanged: (_){},
+  ///   fillColor: WidgetStateProperty.resolveWith<Color>((Set<WidgetState> states) {
+  ///     if (states.contains(WidgetState.disabled)) {
+  ///       return Colors.orange.withOpacity(.32);
+  ///     }
+  ///     return Colors.orange;
+  ///   })
+  /// )
+  /// ```
+  /// {@end-tool}
+  /// {@endtemplate}
+  ///
+  /// If [fillColor] resolves to null for the requested state, then the fill color
+  /// falls back to [activeColor] if the state includes [WidgetState.selected],
+  /// or [inactiveColor] otherwise.
+  final WidgetStateProperty<Color?>? fillColor;
+
   /// The color used if the checkbox is inactive.
   ///
+  /// If [fillColor] returns a non-null color in the unselected
+  /// state, [fillColor] will be used instead of [inactiveColor].
+  ///
   /// By default, [CupertinoColors.inactiveGray] is used.
   final Color? inactiveColor;
 
@@ -318,6 +359,7 @@ class _CupertinoCheckboxState extends State<CupertinoCheckbox> with TickerProvid
   @override
   Widget build(BuildContext context) {
     // Colors need to be resolved in selected and non selected states separately.
+    // The `states` getter constructs a new set every time, making it safe to edit in place.
     final Set<WidgetState> activeStates = states..add(WidgetState.selected);
     final Set<WidgetState> inactiveStates = states..remove(WidgetState.selected);
 
@@ -325,7 +367,11 @@ class _CupertinoCheckboxState extends State<CupertinoCheckbox> with TickerProvid
     // throughout the lifecycle of this build method.
     final Set<WidgetState> currentStates = states;
 
-    final Color effectiveActiveColor = _defaultFillColor.resolve(activeStates);
+    final Color effectiveActiveColor = widget.fillColor?.resolve(activeStates)
+        ?? _defaultFillColor.resolve(activeStates);
+
+    final Color effectiveInactiveColor = widget.fillColor?.resolve(inactiveStates)
+        ?? _defaultFillColor.resolve(inactiveStates);
 
     final BorderSide effectiveBorderSide = _resolveSide(widget.side, currentStates)
       ?? _defaultSide.resolve(currentStates);
@@ -353,7 +399,7 @@ class _CupertinoCheckboxState extends State<CupertinoCheckbox> with TickerProvid
           ..isFocused = currentStates.contains(WidgetState.focused)
           ..isHovered = currentStates.contains(WidgetState.hovered)
           ..activeColor = effectiveActiveColor
-          ..inactiveColor = _defaultFillColor.resolve(inactiveStates)
+          ..inactiveColor = effectiveInactiveColor
           ..checkColor = _defaultCheckColor.resolve(currentStates)
           ..value = value
           ..previousValue = _previousValue

packages/flutter/test/cupertino/checkbox_test.dart

@@ -7,6 +7,7 @@
 //   machines.
 @Tags(<String>['reduced-test-set'])
 library;
+import 'dart:ui';
 
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/foundation.dart';
@@ -575,6 +576,134 @@ void main() {
     );
   });
 
+  testWidgets('Checkbox fill color resolves in enabled/disabled states', (WidgetTester tester) async {
+    const Color activeEnabledFillColor = Color(0xFF000001);
+    const Color activeDisabledFillColor = Color(0xFF000002);
+
+    Color getFillColor(Set<WidgetState> states) {
+      if (states.contains(WidgetState.disabled)) {
+        return activeDisabledFillColor;
+      }
+      return activeEnabledFillColor;
+    }
+
+    final WidgetStateProperty<Color> fillColor = WidgetStateColor.resolveWith(getFillColor);
+
+    Widget buildApp({required bool enabled}) {
+      return CupertinoApp(
+        home: CupertinoCheckbox(
+          value: true,
+          fillColor: fillColor,
+          onChanged: enabled ? (bool? value) { } : null,
+        ),
+      );
+    }
+
+    RenderBox getCheckboxRenderer() {
+      return tester.renderObject<RenderBox>(find.byType(CupertinoCheckbox));
+    }
+
+    await tester.pumpWidget(buildApp(enabled: true));
+    await tester.pumpAndSettle();
+    expect(getCheckboxRenderer(), paints..path(color: activeEnabledFillColor));
+
+    await tester.pumpWidget(buildApp(enabled: false));
+    await tester.pumpAndSettle();
+    expect(getCheckboxRenderer(), paints..path(color: activeDisabledFillColor));
+  });
+
+  testWidgets('Checkbox fill color take precedence over active/inactive colors', (WidgetTester tester) async {
+    const Color activeEnabledFillColor = Color(0xFF000001);
+    const Color activeDisabledFillColor = Color(0xFF000002);
+    const Color activeColor = Color(0xFF000003);
+    const Color inactiveColor = Color(0xFF000004);
+
+    Color getFillColor(Set<WidgetState> states) {
+      if (states.contains(WidgetState.disabled)) {
+        return activeDisabledFillColor;
+      }
+      return activeEnabledFillColor;
+    }
+
+    final WidgetStateProperty<Color> fillColor = WidgetStateColor.resolveWith(getFillColor);
+
+    Widget buildApp({required bool enabled}) {
+      return CupertinoApp(
+        home: CupertinoCheckbox(
+          value: true,
+          fillColor: fillColor,
+          activeColor: activeColor,
+          inactiveColor: inactiveColor,
+          onChanged: enabled ? (bool? value) { } : null,
+        ),
+      );
+    }
+
+    RenderBox getCheckboxRenderer() {
+      return tester.renderObject<RenderBox>(find.byType(CupertinoCheckbox));
+    }
+
+    await tester.pumpWidget(buildApp(enabled: true));
+    await tester.pumpAndSettle();
+    expect(getCheckboxRenderer(), paints..path(color: activeEnabledFillColor));
+
+    await tester.pumpWidget(buildApp(enabled: false));
+    await tester.pumpAndSettle();
+    expect(getCheckboxRenderer(), paints..path(color: activeDisabledFillColor));
+  });
+
+  testWidgets('Checkbox fill color resolves in hovered/focused states', (WidgetTester tester) async {
+    final FocusNode focusNode = FocusNode(debugLabel: 'checkbox');
+    addTearDown(focusNode.dispose);
+
+    tester.binding.focusManager.highlightStrategy = FocusHighlightStrategy.alwaysTraditional;
+    const Color hoveredFillColor = Color(0xFF000001);
+    const Color focusedFillColor = Color(0xFF000002);
+    const Color transparentColor = Color(0x00000000);
+
+    Color getFillColor(Set<WidgetState> states) {
+      if (states.contains(WidgetState.hovered)) {
+        return hoveredFillColor;
+      }
+      if (states.contains(WidgetState.focused)) {
+        return focusedFillColor;
+      }
+      return transparentColor;
+    }
+
+    final WidgetStateProperty<Color> fillColor = WidgetStateColor.resolveWith(getFillColor);
+
+    Widget buildApp({required bool enabled}) {
+      return CupertinoApp(
+        home: CupertinoCheckbox(
+          focusNode: focusNode,
+          value: enabled,
+          fillColor: fillColor,
+          onChanged: enabled ? (bool? value) { } : null,
+        ),
+      );
+    }
+
+    RenderBox getCheckboxRenderer() {
+      return tester.renderObject<RenderBox>(find.byType(CupertinoCheckbox));
+    }
+
+    await tester.pumpWidget(buildApp(enabled: true));
+    focusNode.requestFocus();
+    await tester.pumpAndSettle();
+    expect(focusNode.hasPrimaryFocus, isTrue);
+    expect(getCheckboxRenderer(), paints..path(color: focusedFillColor));
+
+    // Start hovering.
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse);
+    await gesture.addPointer();
+    addTearDown(gesture.removePointer);
+    await gesture.moveTo(tester.getCenter(find.byType(CupertinoCheckbox)));
+    await tester.pumpAndSettle();
+
+    expect(getCheckboxRenderer(), paints..path(color: hoveredFillColor));
+  });
+
   testWidgets('Checkbox configures focus color', (WidgetTester tester) async {
     const Color defaultCheckColor = Color(0xffffffff);
     const Color defaultActiveFillColor = Color(0xff007aff);