Flutter Container - Border Radius, Box Shape, Circle Avatar

import 'package:flutter/material.dart';

class RegisterScreen extends StatefulWidget {
  const RegisterScreen({Key? key}) : super(key: key);

  @override
  _RegisterScreenState createState() => _RegisterScreenState();
}

class _RegisterScreenState extends State<RegisterScreen> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          elevation: 0,
          title: Text("Container Examples"),
        ),
        body: Container(
          width: double.infinity,
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.center,
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              Container(
                height: 150,
                width: 150,
                decoration: BoxDecoration(
                  color: Colors.teal,
                  borderRadius: BorderRadius.all(Radius.circular(20)),
                ),
              ),
              SizedBox(
                height: 10,
              ),
              Container(
                height: 150,
                width: 150,
                decoration: BoxDecoration(
                  shape: BoxShape.circle,
                  color: Colors.green,
                ),
              ),
              Center(
                child: Container(
                  margin: EdgeInsets.all(16),
                  height: 100,
                  width: 100,
                  decoration: BoxDecoration(
                      borderRadius: BorderRadius.circular(52.5),
                      boxShadow: [
                        BoxShadow(
                          color: Colors.black,
                          spreadRadius: 4,
                        )
                      ]),
                  child: CircleAvatar(
                    radius: 30,
                    backgroundImage: NetworkImage('https://randomuser.me/api/portraits/women/26.jpg'),
                  ),
                ),
              ),
            ],
          ),
        ));
  }
}

class HexColor {
  static hexToColor(String hexString) {
    final buffer = StringBuffer();
    if (hexString.length == 6 || hexString.length == 7) buffer.write('FF');
    buffer.write(hexString.replaceFirst('#', ''));
    return Color(int.parse(buffer.toString(), radix: 16));
  }
}

Screenshot :