How to detect If panel in opening or closing of SlidingUpPanel in flutter

Question

I am Using Sliding up Panel using this Package https://pub.dev/packages/sliding_up_panel , I want if Panel of the SlidingPanel is Opening then a value of a variable should be increment ,If Panel is closing then Vakue of variable should be decrement. below is What I have tried .Any help would be apprectiated thanks

  return SlidingUpPanel(
  color: Color(0xFFE44663),
  borderRadius: BorderRadius.only(topLeft: Radius.circular(10.0),topRight:Radius.circular(10.0) ),
  onPanelSlide: (slidingPosition){
    setState(() {
      if(slidingPosition>=0.0 && slidingPosition<1.0){
        amounts++;
      }
      else{
        if(slidingPosition>0.0){
          if(amounts>=1){
            amounts--;
          }
          else{
            amounts=amounts;
          }
        }


      }

    });

Answer 1

as in the link of the package under the Properties headline you can see onPanelOpened, onPanelClosed properties. You can define functions to these properties. onPanelOpened define a function decrease the value, onPanelClosed define a function increase the value.