How to show touch point in front of bar Xamarin ColorPicker

I'm trying to make a color picker bar and customizing I have encountered this problem (I'm learning with Xamarin). The problem is that I don't see how to make a touch pointer in front of the bar. Any idea? How to do it?

Original repo https://github.com/UdaraAlwis/XFColorPickerControl

Color picker

// Painting the Touch point
using (SKPaint paintTouchPoint = new SKPaint())
{
paintTouchPoint.Style = SKPaintStyle.Fill;
paintTouchPoint.Color = SKColors.Black;
paintTouchPoint.IsAntialias = true;

var valueToCalcAgainst = (skCanvasWidth > skCanvasHeight) ? skCanvasWidth : skCanvasHeight;

var pointerCircleDiameterUnits = PointerCircleDiameterUnits+0.05; // 0.6 (Default)
pointerCircleDiameterUnits = (float)pointerCircleDiameterUnits / 10f; //  calculate 1/10th of that value
var pointerCircleDiameter = (float)(valueToCalcAgainst * pointerCircleDiameterUnits);

// Outer circle of the Pointer (Ring)
skCanvas.DrawCircle(
    _lastTouchPoint.X,
    _lastTouchPoint.Y,
    pointerCircleDiameter / 2, paintTouchPoint);

paintTouchPoint.Style = SKPaintStyle.Fill;
paintTouchPoint.Color = SKColors.White;
paintTouchPoint.IsAntialias = true;

valueToCalcAgainst = (skCanvasWidth > skCanvasHeight) ? skCanvasWidth : skCanvasHeight;

pointerCircleDiameterUnits = PointerCircleDiameterUnits; // 0.6 (Default)
pointerCircleDiameterUnits = (float)pointerCircleDiameterUnits / 10f; //  calculate 1/10th of that value
pointerCircleDiameter = (float)(valueToCalcAgainst * pointerCircleDiameterUnits);

// Outer circle of the Pointer (Ring)
skCanvas.DrawCircle(
    _lastTouchPoint.X,
    _lastTouchPoint.Y,
    pointerCircleDiameter / 2, paintTouchPoint);

// Draw another circle with picked color
paintTouchPoint.Color = touchPointColor;

var pointerCircleBorderWidthUnits = PointerCircleBorderUnits; // 0.3 (Default)
var pointerCircleBorderWidth = (float)pointerCircleDiameter *
                                        (float)pointerCircleBorderWidthUnits; // Calculate against Pointer Circle
                
// Inner circle of the Pointer (Ring)
skCanvas.DrawCircle(
    _lastTouchPoint.X,
    _lastTouchPoint.Y,
    ((pointerCircleDiameter - pointerCircleBorderWidth) / 2), paintTouchPoint);
}