Look and feel drawing help

[eokeefee]

I am trying to make a vertical slider show a circle where the value is. I have the following code:

const laf = Engine.createGlobalScriptLookAndFeel();

laf.registerFunction("drawLinearSlider", function(g, obj)
{
    obj.drawOutside = true;

    var a = obj.area;
    var norm = obj.valueNormalized;

    var cx = a[0] + (a[2] / 2);
    var cy = a[1] + a[3] * (1.0 - norm);

    var radius = 15;

    g.setColour(obj.itemColour1);
    g.fillEllipse([cx - radius, cy - radius, radius * 2, radius * 2]);
});

This is working great, however the circle clips when it reaches the top
(The red is the circle).

Is there a way to stop the clipping? I think it's something to do with the bounds of the slider, but I'm not sure...

[ustk]

@eokeefee The full displacement is then the slider height minus the circle height:

laf.registerFunction("drawLinearSlider", function(g, obj)
{
    obj.drawOutside = true;

    var a = obj.area;
    var norm = obj.valueNormalized;

    var radius = 15;
    
    var cx = a[0] + (a[2] / 2);
    
    var start = a[1] + radius;
    var usefulDisplacement = a[3] - 2*radius;
    var cy = start + usefulDisplacement * (1.0 - norm);
    
    g.setColour(obj.itemColour1);
    g.fillEllipse([cx - radius, cy - radius, radius * 2, radius * 2]);
});