code: public static String makeMarginTransform(double owidth, double oheight, double iwidth, double iheight, double xmargin, double ymargin) {
      return makeMarginTransform(owidth, oheight, iwidth, iheight, xmargin, ymargin, xmargin, ymargin);
    }
docs: Make a transform string to add margins
  
  @param owidth Width of outer (embedding) canvas
  @param oheight Height of outer (embedding) canvas
  @param iwidth Width of inner (embedded) canvas
  @param iheight Height of inner (embedded) canvas
  @param xmargin Left and right margin (in inner canvas' units)
  @param ymargin Top and bottom margin (in inner canvas' units)
  @return Transform string