Counter example

readme.md

Counter example

Created with <3 with dartpad.dev.

main.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 MyAppWrapper(title: 'Flutter Full Page Overlay'),
    );
  }
}

class LoadingOverlay {
  LoadingOverlay();

  OverlayEntry? _overlay;

  void show(BuildContext context) {
    if (_overlay == null) {
      _overlay = OverlayEntry(
        builder: (context) => Container(
          alignment: Alignment.center,
          color: const Color(0xc0000000),
          height: double.infinity,
          width: double.infinity,
          child: Container(
            color: Colors.white,
            padding: const EdgeInsets.all(24),
            child: ElevatedButton(
              onPressed: hide,
              child: const Text('Close Overlay'),                  
            ),
          ),
        ),
      );

      Overlay.of(context).insert(_overlay!);
    }
  }

  void hide() {
    if (_overlay != null) {
      _overlay!.remove();
      _overlay = null;
    }
  }
}

class MyAppWrapper extends StatelessWidget {
  const MyAppWrapper({required this.title});
  
  final String title;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text("Nested App Bar"),),
      bottomNavigationBar: BottomNavigationBar(
        backgroundColor: Colors.white,
        items: const [
          BottomNavigationBarItem(
            icon: Icon(Icons.home),
            label: 'Home',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.business),
            label: 'Business',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.school),
            label: 'School',
          ),
        ]
      ),
      body: const MyHomePage(title: 'Nested Scaffold'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  final String title;

  const MyHomePage({
    Key? key,
    required this.title,
  }) : super(key: key);

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {

  final _overlay = LoadingOverlay();
  
  void _showOverlay() {
    _overlay.show(context);  
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: const Center(
        child: Text('Press the FAB to show the overlay'),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _showOverlay,
        tooltip: 'overlay',
        child: const Icon(Icons.add),
      ),
    );
  }
}