public static String getPS(Tree t, List<String> ruleNames,
							   String fontName, int fontSize)
	{
		TreePostScriptGenerator psgen =
			new TreePostScriptGenerator(ruleNames, t, fontName, fontSize);
		return psgen.getPS();
	}
Save this tree in a postscript file using a particular font name and size
tool/src/org/antlr/v4/gui/Trees.java