悬停在 FAB 上时，我不想重建 CustomPaint 小部件

Question

我以为当我悬停在 FAB 上时，只有 FAB 会发生变化，其他一切都会保持不变，但是当我悬停在 FAB 上时，CustomPaint 小部件正在重新绘制。我想知道为什么会这样，因为我认为 CustomPaint 只是在我按下 FAB 时才重新绘制。

我的代码如下

class HomePage extends HookWidget {
  const HomePage({super.key});

  @override
  Widget build(BuildContext context) {
    final toggle = useState(false);

    debugPrint('HomePage rebuild');

    return Scaffold(
      body: Center(
        child: Container(
          height: 250,
          width: 250,
          child: CustomPaint(
            painter: PanelBackend(Colors.red, toggle),
            foregroundPainter:
                PanelFrontend(Colors.blue.withOpacity(1), toggle),
            child: Container(
              height: 100.0,
              width: 100.0,
              color: Colors.transparent,
              child: const Text('Middle'),
            ),
          ),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () => toggle.value = !toggle.value,
        child: const Icon(Icons.add),
      ),
    );
  }
}

class PanelBackend extends CustomPainter {
  final Color color;
  final ValueNotifier<bool> notifier;

  PanelBackend(this.color, this.notifier) : super(repaint: notifier);

  @override
  void paint(Canvas canvas, Size size) {
    final paint = Paint()..color = color;

    final stamp = DateTime.now().millisecondsSinceEpoch;
    debugPrint('$stamp : Backend painted, size: ${size.toString()}');

    canvas.drawRect(
        Rect.fromPoints(Offset.zero, Offset(size.width, size.height)), paint);
  }

  @override
  bool shouldRepaint(covariant PanelBackend oldDelegate) {
    return notifier.value != oldDelegate.notifier.value;
  }
}

class PanelFrontend extends CustomPainter {
  final Color color;

  final ValueNotifier<bool> notifier;

  PanelFrontend(this.color, this.notifier) : super(repaint: notifier);

  @override
  void paint(Canvas canvas, Size size) {
    final paint = Paint()..color = color;

    final stamp = DateTime.now().millisecondsSinceEpoch;
    debugPrint('$stamp : Front painted, size: ${size.toString()}');

    canvas.drawRect(
        Rect.fromPoints(Offset.zero, Offset(size.width, size.height)), paint);
  }

  @override
  bool shouldRepaint(covariant PanelFrontend oldDelegate) {
    return notifier.value != oldDelegate.notifier.value;
  }
}

我尝试使用 ElevatedButton 而不是 FAB，但结果相同，即悬停时，CustomPaint 已重建。

然而，我尝试使用 GestureDetector 而不是 FAB 或 ElevatedButton，然后它就像我想象的那样。