Re: [NTG-context] Arabic protrosion

On Mon, Apr 06, 2009 at 07:30:33AM -0600, Idris Samawi Hamid ادريس سماوي حامد wrote:

On Mon, 06 Apr 2009 00:40:12 -0600, Khaled Hosny wrote:

...

The attached patch adds Arabic coma, semicolon, full stop (used in Urdu) and question mark to font-ext.lua for protrusion. Now, combined with glyph expansion, I don't get any overfull boxes.

Arabic-script microtypography is one of the cornerstones of the Oriental TeX project. We've been studying this matter for some time now:

Because of

a) the normal wide spacing around Arabic punctuation, and

b) the large size of Arabic punctuation relative to Latin,

I'm not sure that protrusion of Arabic-script punctuation is a good idea. It needs a lot of thought, and a lot of testing, before adding it to the system.

Indeed, more testing is needed, but since neither protrusion nor expansion is on by default, I think it is safe to have them now so we can do more testing and tune it later, when someone enables hz features, he should no enough to judge himself about the quality of the result and he can always turn it back off and will lose nothing.

As for glyph expansion, I don't see how that works at all with the current model, except perhaps with very horizontal fonts. But in that case all that's needed is smart tatweel, not glyph expansion. For hq fonts the current glyph expansion model will mess up the contextual connections.

I think the minimal font expansion, that we have, is very unlikely to be noticed by the reader, but I completely agree that great care should be taken, I've been reading some Arabic book few months ago and I'm pretty sure they used the font expansion feature of InDesign because it was very visible and annoying.

Although one can certainly do things with the current model of protrusion and hz, we need more, much more. Khaled, send me some tests off-list and I'll examine them in light of the overall analysis as we prepare for adding Arabic microtypography support, hopefully pretty soon.

I was preparing some test files, when I accidentally removed all files that I was working on recently, since I don't have a backup, it'll take some time.

سلام وعليكم السلام

Regards, Khaled -- Khaled Hosny Arabic localiser and member of Arabeyes.org team Free font developer