Emacs text shaping using Harfbuzz

[Eli Zaretskii <eliz@gnu.org>]

Harfbuzz (harfbuzz.org) is an OpenType text shaping engine.  It is a
modern text shaping engine, is actively developed and maintained, and
supports all the modern platforms which can run Emacs.  Using Harfbuzz
as its text shaping engine will thus allow Emacs to remain on the
leading edge of this technology, and enjoy the advanced features that
become available in other text-editing and reading applications, which
currently Emacs cannot support.  Moreover, we could have a single text
shaping engine supported on all platforms, thus all but eliminating
platform-specific text-shaping issues and limitations.

With this in mind, we asked the Harfbuzz developers to help us
integrate Emacs with Harfbuzz.  The first stage of this job, performed
by the Harfbuzz team, is the new 'harfbuzz' branch now available in
the Emacs Git repository.  This branch currently supports only Posix
platforms, and AFAIK was only tested on GNU/Linux.  Support for other
platforms will be added as the development continues.  (Interested
individuals are, of course, welcome to work on adding their preferred
platforms without waiting for others to do that.)

I'd like to encourage people who build Emacs on GNU/Linux to checkout
and build this branch and report any problems you see.  Please report
these problems using "M-x report-emacs-bug RET", and please CC on the
reports Mohammad Nasirifar <far.nasiri.m@gmail.com>, one of the
Harfbuzz developers who volunteered to help us with this integration.
(You will, of course, need to install or build Harfbuzz on your
system, before building this branch.)

I'd also like to encourage people to study the Harfbuzz integration
code and propose improvements and other changes as you see fit.

Finally, I'd like to take this opportunity to thank the Harfbuzz
development team (CC'ed) for their support.

Enjoy.