Flutter AnimatedSwitcher SlideTransition

main.dart

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  bool isLoggedIn = false;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: AnimatedSwitcher(
        duration: Duration(seconds: 1),
        switchInCurve: Curves.ease,
        switchOutCurve: Threshold(0),
        transitionBuilder: (child, animation) => SlideTransition(
          child: child,
          position: Tween(
            begin: Offset(1, 0),
            end: Offset.zero,
          ).animate(animation),
        ),
        child: isLoggedIn
            ? Scaffold(
                key: ValueKey(1),
                backgroundColor: Colors.blue,
              )
            : Scaffold(
                key: ValueKey(2),
                backgroundColor: Colors.orange,
                body: Center(
                  child: ElevatedButton(
                    onPressed: () => setState(() {
                      isLoggedIn = true;
                    }),
                    child: Text('Log in'),
                  ),
                ),
              ),
      ),
    );
  }
}