import 'package:flutter/material.dart';

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

class MyApp extends StatefulWidget {
  // This widget is the root of your application.
  @override
  MyAppState createState() {
    return new MyAppState();
  }
}

class MyAppState extends State<MyApp> {
  CrossFadeState xFadeState = CrossFadeState.showFirst;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Issue Demo',
      home: Scaffold(
        body: Center(
          child: Container(
            color: Colors.red,
            width: 50,
            height: 50,
            child: GestureDetector(
              onTap: () {
                setState(() {
                  xFadeState == CrossFadeState.showSecond ? xFadeState = CrossFadeState.showFirst : xFadeState = CrossFadeState.showSecond;
                });
              },
              child: Center(
                child: AnimatedCrossFade(
                  firstChild: Text('data'),
                  secondChild: SizedBox(
                    height: 20,
                    width: 20,
                    child: CircularProgressIndicator(),
                  ),
                  duration: Duration(milliseconds: 250),
                  crossFadeState: xFadeState,
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }
}