About the function of the new button I created

I created a new Button Class. This button has a Timer, which is normally gray and changes color after 5 seconds. When tapped, it turns gray again and changes color after 5 seconds. I want to reset the counter (_counter=0) to change the color, but I don’t know how to do it.　This is my　code.

class NewFloatingButton extends StatefulWidget {
  final VoidCallback onTap;
  NewFloatingButton(this.onTap);

  @override
  State<NewFloatingButton> createState() => _NewFloatingButtonState();
}

class _NewFloatingButtonState extends State<NewFloatingButton> {
  int _counter = 0;
  late Timer timer;

  dynamic buttonColor() {
    if (_counter < 6) {
      return Colors.grey;
    } else{
        return Colors.purple;
    }
  }

  @override
  void initState() {
    super.initState();
    timer = Timer.periodic(
      const Duration(seconds: 1),
          (Timer timer) {
        _counter++;
        setState(() {});
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: widget.onTap,
      child: Container(
        height: 50,
        width: 50,
        decoration: BoxDecoration(
          color: buttonColor(),
          borderRadius: BorderRadius.circular(28),
          boxShadow: const [
            BoxShadow(
                spreadRadius: 2,
                blurRadius: 2,
                color: Colors.black12,
                offset: Offset(1, 1))
          ],
        ),
        alignment: Alignment.center,
        child: const Icon(
          Icons.arrow_forward,
          color: Colors.white,
        ),
      ),
    );
  }
}

Where should I put "_counter=0"?

>Solution :

You can update your GestureDetector onTap to look something like this:

@override
  Widget build(BuildContext context) {
    return GestureDetector(
      // Add this
      onTap: (){
        widget.onTap();
         setState((){
           _counter=0;
         });
         },
      child: Container(
        height: 50,
        width: 50,
        decoration: BoxDecoration(
          color: buttonColor(),
          borderRadius: BorderRadius.circular(28),
          boxShadow: const [
            BoxShadow(
                spreadRadius: 2,
                blurRadius: 2,
                color: Colors.black12,
                offset: Offset(1, 1))
          ],
        ),
        alignment: Alignment.center,
        child: const Icon(
          Icons.arrow_forward,
          color: Colors.white,
        ),
      ),
    );
  }