@Override
    public ToScreenProjector getScreenCoordCalculator() {

          return gp -> {
              if (map == null || map.viewport() == null) {
                  return null;
              }
              final Point pt = new Point();
              map.viewport().toScreenPoint(GP_CONVERTER.to(gp), false, pt);
              return new int[]{(int) pt.x, (int) pt.y};
        };
    }
mimics {@link #removeItem(MarkerInterface)} but w/o calling 'populate'
main/src/main/java/cgeo/geocaching/unifiedmap/geoitemlayer/MapsforgeVtmGeoItemLayer.java