how to animate widgets just once? about animator HOT 1 CLOSED

class MyHomePage extends StatelessWidget {
  ///Use a GlobalKey to gain access to the [AnimatorWidgetState],
  ///every animated widget from the flutter_animator package uses this state.
  final GlobalKey<AnimatorWidgetState> _animationKey =
      GlobalKey<AnimatorWidgetState>();

  MyHomePage();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Animate once'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: <Widget>[
            FadeInRight(
                ///We pass in the _animationKey to control our animation
                key: _animationKey,
                preferences: AnimationPreferences(
                  autoPlay: AnimationPlayStates.None,
                ),
                child: Text(
                  'FadeInRight',
                  textAlign: TextAlign.center,
                )),
            FloatingActionButton(
              onPressed: () {
                ///Animate forward once, using the _animationKey supplied
                ///to the BounceInDownWidget above.
                _animationKey.currentState.forward();
              },
              child: Text('Animate Once'),
            )
          ],
        ),
      ),
    );
  }
}