Flutter: Perform an action when a countdown timer reaches 0 - flutter

Question

I've created a screen in Flutter that displays a countdown timer. I'm able to play, pause and restart the timer, but I am trying to figure out how to perform an action when the timer reaches 0 (for example, restart itself).
As the dart file is fairly lengthy, I'm just copying below what I believe to be the relevant portions here. But I can add more if needed.
First I create a widget/class for the countdown timer:
class Countdown extends AnimatedWidget {
Countdown({ Key key, this.animation }) : super(key: key, listenable: animation);
Animation<int> animation;
#override
build(BuildContext context){
return Text(
animation.value.toString(),
style: TextStyle(
fontSize: 120,
color: Colors.deepOrange
),
);
}
}
I then have a stateful widget which creates the controller and also imports some data (gameData.countdownClock is the countdown timer's start time, it comes from user input at an earlier screen):
class _GameScreenState extends State<GameScreen> with TickerProviderStateMixin {
AnimationController _controller;
_GameScreenState(this.gameData);
GameData gameData;
#override
void initState() {
super.initState();
_controller = AnimationController(
vsync: this,
duration: Duration(seconds: gameData.countdownClock),
);
}
And then the container that displays the clock:
Container(
child: Countdown(
animation: StepTween(
begin: gameData.countdownClock,
end: 0,
).animate(_controller),
),
),
Do I have to add a listener in that last container? Or somewhere else? (Or something else entirely!)
Any help is appreciated. Thank you

Answer 1

I found the answer on this page:
After complete the widget animation run a function in Flutter
I needed to add .addStatusListener to the animation controller in the initState().
So the new initState() code looks like this:
void initState() {
super.initState();
_controller = AnimationController(
vsync: this,
duration: Duration(seconds: gameData.countdownClock),
);
_controller.addStatusListener((status){
if(status == AnimationStatus.completed){
_controller.reset();
}
}
);
}

Answer 2

Possible value of Animation controller is between 0 to 1.
So I think you have to add listener on gamedata.countDownClock
Please check the below code you might get some idea from it.
import 'dart:async';
import 'package:flutter/material.dart';
class GameScreen extends StatefulWidget {
#override
_GameScreenState createState() => _GameScreenState();
}
class _GameScreenState extends State<GameScreen> with SingleTickerProviderStateMixin {
int countdownClock = 10;
#override
void initState() {
super.initState();
// Your Game Data Counter Change every one Second
const oneSec = const Duration(seconds:1);
new Timer.periodic(oneSec, (Timer t) {
// Restart The Counter Logic
if (countdownClock == 0)
countdownClock = 11;
setState(() { countdownClock = countdownClock - 1; });
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text("")),
body: Center(
child: Text('$countdownClock')
),
);
}
}