AnimatedContainer

HomeView

class HomeView extends StatefulWidget {
  const HomeView({Key key}) : super(key: key);

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

class _HomeViewState extends State<HomeView> {

  // Add variable to top of class
  Alignment childAlignment = Alignment.center;

  @override
  Widget build(BuildContext context) {
    
    return Scaffold(
      backgroundColor: Colors.white30,
      body: AnimatedContainer(
        curve: Curves.easeOut,
        duration: Duration(
          milliseconds: 1000,
        ),
        width: double.infinity,
        height: double.infinity,
        padding: const EdgeInsets.all(20),
        alignment: Alignment.bottomCenter,
        child: Container(
          margin: const EdgeInsets.only(bottom: 50),
          decoration: BoxDecoration(
            borderRadius: BorderRadius.all(
              Radius.circular(10)
            ),
            color: Colors.white.withAlpha(200),
          ),
          width: 360,
          height: 200,
          padding: const EdgeInsets.all(20),
          alignment: Alignment.center,
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: <Widget>[
              Text(
                'teste',
                style: TextStyle(fontSize: 30),
              ),
              TextField(
                decoration: InputDecoration(
                  hasFloatingPlaceholder: true, 
                  hintText: 'Enter things here'
                  ),
              )
            ],
          ),
        ),
      ),
    );
  }
}