如何在flutter中调用圆形滑块的值？

import 'package:flutter/material.dart';

class CircleSlider extends StatefulWidget {
  @override
  _CircleSliderState createState() => _CircleSliderState();
}

class _CircleSliderState extends State<CircleSlider> {
  double _sliderValue = 0.0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Circle Slider'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            CustomPaint(
              size: Size(200, 200),
              painter: CirclePainter(value: _sliderValue),
            ),
            SizedBox(height: 20),
            Slider(
              min: 0.0,
              max: 100.0,
              value: _sliderValue,
              onChanged: (value) {
                setState(() {
                  _sliderValue = value;
                });
              },
            ),
          ],
        ),
      ),
    );
  }
}

class CirclePainter extends CustomPainter {
  final double value;

  CirclePainter({required this.value});

  @override
  void paint(Canvas canvas, Size size) {
    double radius = size.width / 2;
    double angle = 2 * value * 3.14 / 100;

    Offset center = Offset(radius, radius);
    Paint outerCircle = Paint()
      ..strokeWidth = 10
      ..color = Colors.blue
      ..style = PaintingStyle.stroke;

    canvas.drawCircle(center, radius, outerCircle);

    Paint progressArc = Paint()
      ..strokeWidth = 10
      ..color = Colors.green
      ..style = PaintingStyle.stroke
      ..strokeCap = StrokeCap.round;

    canvas.drawArc(
        Rect.fromCircle(center: center, radius: radius),
        -90 * 3.14 / 180,
        angle,
        false,
        progressArc);
  }

  @override
  bool shouldRepaint(CustomPainter oldDelegate) {
    return true;
  }
}

void main() {
  runApp(MaterialApp(
    home: CircleSlider(),
  ));
}