How to use LinearGradinet with transparent AppBar

 

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(
        extendBodyBehindAppBar: true,
        appBar: AppBar(
          backgroundColor: Colors.transparent,
          elevation: 0,
          title: Text("AppBar Title"),
        ),
        body: Container(
          decoration: BoxDecoration(
            gradient: LinearGradient(
                begin: Alignment.topCenter,
                end: Alignment.bottomCenter,
                colors: [
                  HexColor.hexToColor("#D76984"),
                  HexColor.hexToColor("#2369C0")
                ]),
          ),
        ));
  }
}

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 :