Re: [emacs-bidi] state of BIDI within stable GNU emacs (UTF8) nikud

[Eli Zaretskii]

> Date: Mon, 21 Nov 2005 02:56:37 +0330
> From: Hossein Noorikhah <address@hidden>
> 
> I want to know more about using Pango for text rendering that can
> solve these kind of problems. I read in mailing list achieves that
> Emacs developers have tried Pango for text rendering, but they found
> it not suitable for Emcas. I want to know why?

I once wrote here the reason: Pango, like fribidi, is a batch-mode
reordering library: you hand it a buffer with text and it returns it
reordered for display.

By contrast, Emacs needs a reordering function that could be called
repeatedly, and will on every call return the next character in the
visual order.  This is because the Emacs display engine walks the
buffer one character at a time and decides how to display it based on
data structures built by the application.

I wrote such a sequential version of bidi reordering, and it was
integrated into redisplay on a special branch of Emacs CVS.  But no
one had time to debug it and expand it, unfortunately.