Flutter使用3种颜色和值绘制一个圆圈边框

import 'package:flutter/material.dart';

class CircleBorderWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return CustomPaint(
      painter: CircleBorderPainter(),
    );
  }
}

class CircleBorderPainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final center = Offset(size.width / 2, size.height / 2);
    final radius = size.width / 2;

    final outerCircle = Paint()
      ..color = Colors.red
      ..style = PaintingStyle.stroke
      ..strokeWidth = 2.0;

    final middleCircle = Paint()
      ..color = Colors.green
      ..style = PaintingStyle.stroke
      ..strokeWidth = 4.0;

    final innerCircle = Paint()
      ..color = Colors.blue
      ..style = PaintingStyle.stroke
      ..strokeWidth = 6.0;

    canvas.drawCircle(center, radius, outerCircle);
    canvas.drawCircle(center, radius - 3.0, middleCircle);
    canvas.drawCircle(center, radius - 6.0, innerCircle);
  }

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