code: public ScaleLevel getLevelFor(Font font, FontRenderContext frc, DoubleTransform transformer, boolean horizontal, double xy)
      {
          return getLevelFor(font, frc, transformer, horizontal, xy, null);
      }
docs: Returns highest level where drawn labels don't overlap
  @param font
  @param frc
  @param transformer
  @param horizontal
  @param xy Lines constant value
  @return