pageview.dart

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  static const Widget _home = HomePage();
  @override
  Widget build(BuildContext context) => MaterialApp(
        home: _home,
      );
}

class HomePage extends StatefulWidget {
  const HomePage();

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

class _HomePageState extends State<HomePage> {
  PageController _controller;
  List<int> _lenght = [0, 1, 2];
  @override
  void initState() {
    super.initState();
    _controller = PageController(initialPage: 1, viewportFraction: 0.8);
  }

  @override
  void dispose() {
    _controller?.dispose();
    super.dispose();
  }

  void _add() => setState(() {
        _lenght.add(_lenght.length);
      });

  void _remove() => setState(() {
        if (_lenght.length > 1) {
          _lenght.removeAt(0);
          _controller.jumpToPage(_controller.page.floor() - 1);
        }
      });

  void _reset() => setState(() {
        _lenght = [0, 1, 2];
      });

  @override
  Widget build(BuildContext context) => Scaffold(
        appBar: AppBar(
          actions: <Widget>[
            Padding(
              padding: const EdgeInsets.only(right: 20.0),
              child: IconButton(
                icon: const Icon(Icons.refresh),
                onPressed: _reset,
              ),
            ),
            Padding(
              padding: const EdgeInsets.only(right: 20.0),
              child: IconButton(
                icon: const Icon(Icons.remove),
                onPressed: _remove,
              ),
            ),
            Padding(
              padding: const EdgeInsets.only(right: 20.0),
              child: IconButton(
                icon: const Icon(Icons.add),
                onPressed: _add,
              ),
            ),
          ],
        ),
        body: PageView(
          controller: _controller,
          children: <Widget>[
            for (int i in _lenght)
              Padding(
                padding: const EdgeInsets.all(32.0),
                child: Container(
                  color: Colors.blueAccent[100],
                  alignment: Alignment.center,
                  child: Text(
                    '$i',
                    style: const TextStyle(fontSize: 32),
                  ),
                ),
              ),
          ],
        ),
      );
}