CustomPainter navbar with center floating

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CustomPainter navbar with center floating.dart

// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  const MyHomePage({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('CustomPainter'),
      ),
      body: SingleChildScrollView(
        padding: const EdgeInsets.all(20),
        child: Column(
          children: [
            Stack(
              children: [
                Padding(
                  padding: const EdgeInsets.only(top: 45),
                  child: SizedBox(
                    width: double.infinity,
                    child: CustomPaint(
                      size: const Size(double.infinity, 64),
                      painter: ClipperNavbar(),
                    ),
                  ),
                ),
                Align(
                  alignment: Alignment.topCenter,
                  child: Center(
                    child: FloatingActionButton(
                      onPressed: () {},
                      child: const Icon(Icons.home),
                    ),
                  ),
                ),
              ],
            ),
          ],
        ),
      ),
    );
  }
}

class ClipperNavbar extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    Paint paint = Paint()
      ..color = Colors.redAccent
      ..style = PaintingStyle.fill;

    final double sw = size.width;
    final double sh = size.height;

    const double radius = 20;
    const double cradius = 45; // center radius width
    const double ipy = cradius / 3;

    Path path = Path()
      ..moveTo(0, radius)
      ..quadraticBezierTo(0, 0, radius, 0) // radius left
      ..lineTo(sw / 2 - cradius, 0)
      ..quadraticBezierTo(
          sw / 2 - cradius * 0.75, ipy / 3, sw / 2 - cradius * 0.5, ipy)
      ..arcToPoint(
        Offset(sw / 2 + cradius * 0.5, ipy),
        radius: const Radius.circular(cradius),
        clockwise: false,
      )
      ..quadraticBezierTo(
          sw / 2 + cradius * 0.75, ipy / 3, (sw / 2) + cradius, 0)
      ..lineTo(sw - radius, 0)
      ..quadraticBezierTo(sw, 0, sw, radius) // radius right
      ..lineTo(sw, sh)
      ..lineTo(0, sh)
      ..close();

    canvas.drawPath(path, paint);
  }

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