Preview custom goo that can cast itself to geometry

Grasshopper Developer
1

Is it possible to make Grasshopper preview a custom data type that can cast itself to geometry automatically?

The custom type, let’s call it CustomType is wrapped inside a GH_Goo<CustomType> which stores among its data a reference to a Curve.

Here is the code I use to cast this to a curve, which works if it is connected to something that expects curves, but it does not preview the curves in Rhino’s viewport.

private Curve m_storedCurve;

public override bool CastTo<Q>(ref Q target) {
    if (typeof(Q).IsAssignableFrom(typeof(CustomType))) {
        if (Value is null)
            target = default(Q);
        else
            target = (Q)(object)Value;
        return true;
    }

    if (typeof(Q).IsAssignableFrom(typeof(GH_Curve))) {
        if (Value is null)
            target = default(Q);
        else
            target = (Q)(object)new GH_Curve(m_storedCurve);
        return true;
    }

    target = default(Q);
    return false;
}

public override bool CastFrom(object source) {
    if (source is null) return false;
    if (source is CustomType) {
        this.Value = (CustomType)source;
        return true;
    }
    return false;
}

Is it possible to make this preview automatically without drawing the curves myself in the DrawViewportWires method?