Add 30 seconds more to the timer - flutter

Question

Hello I am doing a flutter app , and I want to use a button to add 30s more to the time when it's pressed. The timer starts with 60 seconds , but I want the user to be able to add 30 seconds more if he needs . I only find at the controller(of time) the options like: reverse() , reset() , resync() but nothing to add the time. This is what I used in the beginning of the code ( I will post only some paths because the code is very big)
class _CountDownTimerState extends State<CountDownTimer>
with TickerProviderStateMixin {
AnimationController controller;
String get timerString {
Duration duration = controller.duration * controller.value;
return '${duration.inMinutes}:${(duration.inSeconds % 60).toString().padLeft(2, '0')}';
}
#override
void initState() {
super.initState();
controller = AnimationController(
vsync: this,
duration: Duration(seconds: 60),
);
}
and this is how I write my code for the button with +30s but it only reset the time to 00:30seconds.
child: RaisedButton(
onPressed: () {
if (controller.isAnimating)
controller.duration = Duration(seconds: 30);
},
color: Colors.white,
shape: RoundedRectangleBorder(
borderRadius: new BorderRadius.circular(30),
),
textColor: Colors.black,
child: Text("Give player +30s ")),
),

Answer 1

Here is a Solution using an AnimationController combined with a Timer. I used an initial time of 10 seconds and a time increase of 5 seconds for a faster demo.
import 'dart:async';
import 'package:flutter/material.dart';
void main() {
runApp(
MaterialApp(
debugShowCheckedModeBanner: false,
title: 'Timer Demo',
home: HomePage(),
),
);
}
class HomePage extends StatefulWidget {
#override
_HomePageState createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
bool done = false;
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: done
? Text('TIME OUT')
: CountDownTimer(
onCompleted: () => setState(() => done = true),
),
),
);
}
}
class CountDownTimer extends StatefulWidget {
final VoidCallback onCompleted;
const CountDownTimer({
Key key,
this.onCompleted,
}) : super(key: key);
#override
_CountDownTimerState createState() => _CountDownTimerState();
}
class _CountDownTimerState extends State<CountDownTimer>
with TickerProviderStateMixin {
AnimationController _controller;
Timer _timer;
int _elapsed;
#override
void initState() {
super.initState();
// AnimationController
_controller = AnimationController(vsync: this, duration: kInitialTime);
_controller.addListener(() => setState(() {}));
_controller.addStatusListener(
(AnimationStatus status) {
if (status == AnimationStatus.completed) {
_timer.cancel();
widget.onCompleted();
}
},
);
// Elapsed Counter
_elapsed = 0;
_timer = Timer.periodic(
Duration(seconds: 1),
(_) => setState(() => _elapsed++),
);
// Launch the Controller
_controller.forward();
}
void increaseTime([int extraTime = kExtraTime]) {
_controller.duration =
Duration(seconds: _controller.duration.inSeconds + extraTime);
_controller.reset();
_controller.forward(from: _elapsed / _controller.duration.inSeconds);
}
#override
void dispose() {
_controller.dispose();
_timer.cancel();
super.dispose();
}
#override
Widget build(BuildContext context) {
return Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
CircularProgressIndicator(
value: _controller.value,
backgroundColor: Colors.black12,
),
const SizedBox(height: 12.0),
Text('$_elapsed / ${_controller.duration.inSeconds}'),
const SizedBox(height: 24.0),
ElevatedButton(
onPressed: () => increaseTime(),
child: Text('MORE TIME'),
),
],
);
}
}
// CONFIGURATION
const Duration kInitialTime = Duration(seconds: 10);
const int kExtraTime = 5;

Answer 2

You are setting the duration to 30 seconds, what you need to do instead is add to the remaining duration. You can probably use the + operator of the Duration class: https://api.dart.dev/stable/2.10.5/dart-core/Duration/operator_plus.html
Something like this:
onPressed: () {
if (controller.isAnimating) {
controller.duration += Duration(seconds: 30);
}
},
Not sure if the controller actually supports this.