Stretching letter and slanted-baseline formatting for Arabic, Hebrew, and Persian with ditroff/ffortid and dynamic PostScript fonts

This paper describes an extension to ditroff/ffortid, a system for formatting bi-directional text in Arabic, Hebrew and Persian. The previous version of the system is able to format mixed left-to-right and rightto-left text using fonts with separated letters or with connecting letters and only connection stretching, achieved by repeating fixed-length baseline fillers. The latest extension adds the abilities to stretch letters themselves, as is common in Arabic, Hebrew and Persian calligraphic printing, and to slant the baselines of words, as is common in Persian calligraphic printing. The extension consists of modifications in ffortid that allow it to interface with (1) dynamic POSTSCRIPT fonts to which one can pass to the outline procedure for any stretchable and/or connected letter, parameters specifying the amounts of stretch for the letter itself and/or for the connecting parts of the letter, and (2) POSTSCRIPT fonts whose characters are slanted so that merely applying show to a word ends up printing that entire word on a single slanted baseline. As a self-test, this paper was formatted using the described system, and it contains many examples of text written in Arabic, Hebrew and Persian. Copyright  1999 John Wiley & Sons, Ltd.