private void Update() { ILocation center = Center; if ((ParentMap == null) || (center == null)) { return; } IProjection viewPortProjection = ParentMap.ViewPortProjection; double scaleFactor = viewPortProjection.CartesianScaleFactor(center); _ellipse.RadiusY = RadiusY * scaleFactor; _ellipse.RadiusX = RadiusX * scaleFactor; _ellipse.Center = viewPortProjection.ToCartesian(center).ToPoint(); InvalidateMeasure(); }