confirm method
override
Called when the user input that triggered this feature's appearance was confirmed.
Typically causes the ink to propagate faster across the material. By default this method does nothing.
Implementation
@override
void confirm() {
final int duration = (_targetRadius / _kSplashConfirmedVelocity).floor();
_radiusController
..duration = Duration(milliseconds: duration)
..forward();
_alphaController!.forward();
}