animations package OpenContainer

main.dart

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:animations/animations.dart';

void main() async {
  runApp(
    MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Container(
          color: Colors.black54,
          child: Align(
            alignment: Alignment.bottomCenter,
            child: OpenContainer(
              closedBuilder: (BuildContext context, void Function() action) {
                return RaisedButton(
                  child: Text('Open Content'),
                  onPressed: action,
                );
              },
              openBuilder: (_, __) {
                return NextScreen(
                  deleted: true,
                );
              },
            ),
          ),
        ),
      ),
    ),
  );
}

class NextScreen extends StatelessWidget {
  final bool deleted;

  const NextScreen({Key key, this.deleted}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Builder(builder: (context) {
      if (deleted) {
        Timer(
            Duration.zero,
            () => showDialog(
                context: context,
                builder: (_) => AlertDialog(
                      title: Text('Content Deleted'),
                      actions: <Widget>[FlatButton(child: Text('Ok'), onPressed: () => Navigator.pop(context))],
                    )));
      }
      return Scaffold(
        appBar: AppBar(),
        body: Container(
          color: Colors.white,
          child: Center(child: Text('Content')),
        ),
      );
    });
  }
}