code: @Nonnull
    public final IMPLTYPE scaleBestMatching (@Nonnegative final int nMaxWidth, @Nonnegative final int nMaxHeight)
    {
      if (m_aExtent != null)
        m_aExtent = m_aExtent.getBestMatchingSize (nMaxWidth, nMaxHeight);
      return thisAsT ();
    }
docs: Scales the image so that neither with nor height are exceeded, keeping the
  aspect ratio.
  
  @param nMaxWidth
  Maximum with
  @param nMaxHeight
  Maximum height
  @return the correctly resized image tag