forward method
Implementation
Future<void> forward() async {
final tween = Tween<double>(
begin: _controller.value,
end: 1,
);
_animation = _controller
.drive(
CurveTween(
curve: Interval(
tween.begin!,
tween.end!,
curve: forwardCurve,
),
),
)
.drive(tween);
await _controller.forward();
_animation = _controller;
}