code: public ScaleLevel getLevelFor(Font font, boolean horizontal, double xy)
      {
          return getLevelFor(font, DEFAULT_FONTRENDERCONTEXT, horizontal, xy);
      }
docs: Returns highest level where drawn labels don't overlap using identity
  transformer and FontRenderContext with identity AffineTransform, no
  anti-aliasing and fractional metrics
  @param font
  @param horizontal
  @param xy Lines constant value
  @return