import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Teste Animação',
      home: Animacao(),
    );
  }
}

class Animacao extends StatefulWidget {
  @override
  _AnimacaoState createState() => _AnimacaoState();
}

class _AnimacaoState extends State<Animacao> {
  double containerHeight = 150;
  double containerWidth = 150;
  bool isExpanded = false;


  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Exemplo'),
      ),
      body: Center(
        child: GestureDetector(
          onTap: () {
            setState((){
              isExpanded = !isExpanded;
            });
          },
          child: AnimatedContainer(
            duration: Duration(
              milliseconds: 1000,
            ),
            curve: Curves.bounceOut,

            decoration: BoxDecoration(
              borderRadius: BorderRadius.all(
                Radius.circular(isExpanded ? 32 : 4),
              ),
              color: isExpanded ? Colors.green : Colors.blue,
            ),            
            height: isExpanded ? 250 : 150,
            width: isExpanded ? 250 : 150,
          ),
        ),
      ),
    );
  }
}