Support Font Shaping for Arabic/Persian

[amrza]

Some languages like Arabic or Persian, needs some sorts of font shaping, because they are not actually fixed-width and most of the time the letters should join together in a word. Linux Distros like Debian, Ubuntu and others compile Emacs with libotf and libm17n to get this ability. in OS X, bidirectional display works great but letters are not display correctly. is it possible for emacsformacosx.com to build Emacs with support of these libraries?

[caldwell]

I don't know much about Emacs font support, but after a cursory look it appears that libotf and libm17n are only used in the X backend. The Mac stuff appears to use Mac native APIs to get the shapes, directions, etc. In the NEWS file (C-h n) I see this:

** For OSX >= 10.5, the Core text based font backend from the Mac port is used.
For GNUStep and OSX 10.4 the old backend is used.
To use the old backend by default, do on the command line:
% defaults write org.gnu.Emacs FontBackend ns

This change seems to have happened around 2013-09-15, so I would suggest trying a nightly build later than that to see if that fixes your issue. I'm using the nightly from 2013-12-24 which has been stable so far (though I only have a few days on it).

If it still doesn't work, I would file a bug with the Emacs maintainers with M-x report-emacs-bug, since I don't believe (at this point) that it is a bug in my Emacs build scripts. Please feel free to reopen this bug if you feel I'm wrong.

[amrza]

You were right... i thought the problem was with libotf and libm17n, but after more research it turns out they are only effective when be used under X backend... as you have suggested, i use a nightly build (Emacs-2013-12-30), and yes, the problem is gone and the fonts looks great. thanks.