Emacs text shaping using Harfbuzz

Emacs text shaping using Harfbuzz

[Eli Zaretskii]

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.

Re: Emacs text shaping using Harfbuzz

[Paul Eggert]

[-- Attachment #1: Type: text/plain, Size: 746 bytes --]

The Emacs harfbuzz branch built fine for me on Fedora 29 (no surprise). 
I saw no problems, not that I would catch many (the Arabic I saw 
displayed OK to me, but I don't read Arabic so am not the best person to 
judge).

One minor tweak proposed in the attached patch, for simplicity/clarity 
in the mainstream-Harbuzz code.

I see that Harbuzz is disabled by default by 'configure', and that 
there's an environment variable to disable it at runtime. I propose 
removing the environment variable, and enabling Harfbuzz by default at 
'configure' time (if the Harbuzz libraries are available), as I don't 
see much point in nudging users away from Harfbuzz.

I see there are some FIXMEs and suchlike comments. Will someone be 
working on them?


[-- Attachment #2: hb.diff --]
[-- Type: text/x-patch, Size: 1169 bytes --]

diff --git a/src/ftfont.c b/src/ftfont.c
index a645bbf029..47442df0e5 100644
--- a/src/ftfont.c
+++ b/src/ftfont.c
@@ -478,28 +478,27 @@ ftfont_get_otf (struct ftfont_info *ftfont_info)
 
 #ifdef HAVE_HARFBUZZ
 
-#ifndef HAVE_HB_FT_FONT_CREATE_REFERENCED
+# ifndef HAVE_HB_FT_FONT_CREATE_REFERENCED
 static void
 ft_face_destroy (void *data)
 {
-  FT_Done_Face ((FT_Face) data);
+  FT_Done_Face (data);
 }
-#endif
+
+static hb_font_t *
+hb_ft_font_create_referenced (FT_Face face)
+{
+  FT_Reference_Face (face);
+  return hb_ft_font_create (face, ft_face_destroy);
+}
+# endif
 
 static hb_font_t *
 ftfont_get_hb_font (struct ftfont_info *ftfont_info)
 {
   if (! ftfont_info->hb_font)
-    {
-      hb_font_t *hb_font;
-#ifdef HAVE_HB_FT_FONT_CREATE_REFERENCED
-      hb_font = hb_ft_font_create_referenced (ftfont_info->ft_size->face);
-#else
-      FT_Reference_Face (ftfont_info->ft_size->face);
-      hb_font = hb_ft_font_create (ftfont_info->ft_size->face, ft_face_destroy);
-#endif
-      ftfont_info->hb_font = hb_font;
-    }
+    ftfont_info->hb_font
+      = hb_ft_font_create_referenced (ftfont_info->ft_size->face);
   return ftfont_info->hb_font;
 }
 

Re: Emacs text shaping using Harfbuzz

[Khaled Hosny]

On Thu, Dec 13, 2018 at 10:47:18AM -0800, Paul Eggert wrote:
> I see that Harbuzz is disabled by default by 'configure', and that there's
> an environment variable to disable it at runtime. I propose removing the
> environment variable, and enabling Harfbuzz by default at 'configure' time
> (if the Harbuzz libraries are available), as I don't see much point in
> nudging users away from Harfbuzz.

The environment variable is to allow for easily switching HarfBuzz
on/off during development without re-compiling, when I ported other
projects to HarfBuzz that was handy in debugging regressions caused by
HarfBuzz integration.

Regards,
Khaled

Re: Emacs text shaping using Harfbuzz

[Eli Zaretskii]

> Cc: Khaled Hosny <dr.khaled.hosny@gmail.com>,
>  Ebrahim Byagowi <ebraminio@gmail.com>, Kenichi Handa <handa@gnu.org>,
>  John Wiegley <johnw@gnu.org>, Mohammad Nasirifar <far.nasiri.m@gmail.com>,
>  Behdad Esfahbod <behdad@behdad.org>
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Thu, 13 Dec 2018 10:47:18 -0800
> 
> The Emacs harfbuzz branch built fine for me on Fedora 29 (no surprise). 
> I saw no problems, not that I would catch many (the Arabic I saw 
> displayed OK to me, but I don't read Arabic so am not the best person to 
> judge).

Thanks for trying the branch.

> One minor tweak proposed in the attached patch, for simplicity/clarity 
> in the mainstream-Harbuzz code.

IMO, for such obviously correct fixes, you should just go ahead and
push.

> I see that Harbuzz is disabled by default by 'configure', and that 
> there's an environment variable to disable it at runtime. I propose 
> removing the environment variable, and enabling Harfbuzz by default at 
> 'configure' time (if the Harbuzz libraries are available), as I don't 
> see much point in nudging users away from Harfbuzz.

I agree to enabling it by default if the necessary libraries are
found.

As for disabling at run time, I think this should be reworked to use
the same framework as with other font back-ends, which can be disabled
at runtime by invoking Emacs with the appropriate -xrm switch.  AFAIU,
currently the Harfbuzz code just piggy-backs xftfont, but it really
should be a separate font backend, IMO.

> I see there are some FIXMEs and suchlike comments. Will someone be 
> working on them?

I very much hope so ;-)  The branch is supposed to be WIP, not a
finished result, not yet anyway.

Re: Emacs text shaping using Harfbuzz

[Eli Zaretskii]

> Date: Thu, 13 Dec 2018 21:48:24 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: dr.khaled.hosny@gmail.com, ebraminio@gmail.com, behdad@behdad.org,
> 	johnw@gnu.org, far.nasiri.m@gmail.com, emacs-devel@gnu.org, handa@gnu.org
> 
> > Cc: Khaled Hosny <dr.khaled.hosny@gmail.com>,
> >  Ebrahim Byagowi <ebraminio@gmail.com>, Kenichi Handa <handa@gnu.org>,
> >  John Wiegley <johnw@gnu.org>, Mohammad Nasirifar <far.nasiri.m@gmail.com>,
> >  Behdad Esfahbod <behdad@behdad.org>
> > From: Paul Eggert <eggert@cs.ucla.edu>
> > Date: Thu, 13 Dec 2018 10:47:18 -0800
> > 
> > The Emacs harfbuzz branch built fine for me on Fedora 29 (no surprise). 
> > I saw no problems, not that I would catch many (the Arabic I saw 
> > displayed OK to me, but I don't read Arabic so am not the best person to 
> > judge).
> 
> Thanks for trying the branch.

Btw, we should be able to get support for popular features that will
benefit users of simple scripts as well, like colored emoji and
ligatures.  We just need to extend Emacs itself for that, but AFAIK
Harfbuzz does support these features.  Work in these areas will be
greatly appreciated.

Re: Emacs text shaping using Harfbuzz

[Eli Zaretskii]

> Date: Thu, 13 Dec 2018 21:48:24 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: dr.khaled.hosny@gmail.com, ebraminio@gmail.com, behdad@behdad.org,
> 	johnw@gnu.org, far.nasiri.m@gmail.com, emacs-devel@gnu.org, handa@gnu.org
> 
> > Cc: Khaled Hosny <dr.khaled.hosny@gmail.com>,
> >  Ebrahim Byagowi <ebraminio@gmail.com>, Kenichi Handa <handa@gnu.org>,
> >  John Wiegley <johnw@gnu.org>, Mohammad Nasirifar <far.nasiri.m@gmail.com>,
> >  Behdad Esfahbod <behdad@behdad.org>
> > From: Paul Eggert <eggert@cs.ucla.edu>
> > Date: Thu, 13 Dec 2018 10:47:18 -0800
> > 
> As for disabling at run time, I think this should be reworked to use
> the same framework as with other font back-ends, which can be disabled
> at runtime by invoking Emacs with the appropriate -xrm switch.

And also by using the corresponding font-backend frame parameter.

Re: Emacs text shaping using Harfbuzz

[Kaushal Modi]

[-- Attachment #1: Type: text/plain, Size: 1130 bytes --]

On Thu, Dec 13, 2018 at 10:41 AM Eli Zaretskii <eliz@gnu.org> wrote:

> 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 do have harfbuzz 1.0.3 installed on my system (RHEL 6.8).

How do I build with harfbuzz? Would I need to pass some switch to configure
to enable that?

Using my regular build script, I get this in the configure step:

  Does Emacs use -lxml2?                                  yes
  Does Emacs use -lfreetype?                              yes
  Does Emacs use HarfBuzz?
no                       <-------------
  Does Emacs use -lm17n-flt?                              yes
  Does Emacs use -lotf?                                   yes
  Does Emacs use -lxft?                                   yes

[-- Attachment #2: Type: text/html, Size: 1872 bytes --]

Re: Emacs text shaping using Harfbuzz

[Paul Eggert]

On 12/13/18 11:38 AM, Kaushal Modi wrote:
> How do I build with harfbuzz? Would I need to pass some switch to 
> configure to enable that?

Yes, run './configure --with-harfbuzz'.

Hmm, there should be something in etc/NEWS about this and about Harfbuzz 
in general.

Re: Emacs text shaping using Harfbuzz

[Eli Zaretskii]

> Cc: dr.khaled.hosny@gmail.com, ebraminio@gmail.com, behdad@behdad.org,
>  John Wiegley <johnw@gnu.org>, far.nasiri.m@gmail.com,
>  Emacs developers <emacs-devel@gnu.org>, "K. Handa" <handa@gnu.org>
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Thu, 13 Dec 2018 11:48:10 -0800
> 
> Yes, run './configure --with-harfbuzz'.
> 
> Hmm, there should be something in etc/NEWS about this and about Harfbuzz 
> in general.

Yes.  Patches are welcome.

Re: Emacs text shaping using Harfbuzz

[Kaushal Modi]

[-- Attachment #1: Type: text/plain, Size: 1197 bytes --]

On Thu, Dec 13, 2018 at 2:48 PM Paul Eggert <eggert@cs.ucla.edu> wrote:

Yes, run './configure --with-harfbuzz'.
>

Thanks. That worked. This time the configure detected harfbuzz and it's
compiling right now.

To the Harfbuzz devs:

I have some specific notes on how to install Harfbuzz. I made these when I
installed 1.0.3.

Notes::

/freetype - last downloaded version -- 2.6/
/harfbuzz - last downloaded version -- 1.0.3/

https://bugs.freedesktop.org/show_bug.cgi?id=75652

freetype depends on harfbuzz and vice versa. To solve this chicken and egg
problem, do this.

1. First install freetype *without harfbuzz*
   #+BEGIN_SRC shell
   make distclean
   ./configure --prefix=$HOME/usr_local/${MY_OSREV} --without-harfbuzz
   make
   make install
   #+END_SRC
2. Then install harfbuzz
   #+BEGIN_SRC shell
   make distclean
   ./configure --prefix=$HOME/usr_local/${MY_OSREV}
   make
   make install
   #+END_SRC
3. Reinstall freetype *with harfbuzz*
   #+BEGIN_SRC shell
   make distclean
   ./configure --prefix=$HOME/usr_local/${MY_OSREV}
   make
   make install
   #+END_SRC

====

Does this harfbuzz/freetype cross-dependency still apply if trying to
install the latest harfbuzz version?

[-- Attachment #2: Type: text/html, Size: 1868 bytes --]

Re: Emacs text shaping using Harfbuzz

[Richard Stallman]

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

Thank you, all of you, for working on this.

-- 
Dr Richard Stallman
President, Free Software Foundation (https://gnu.org, https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)

Re: Emacs text shaping using Harfbuzz

[Ken Brown]

On 12/13/2018 10:39 AM, Eli Zaretskii wrote:
> I'd like to encourage people who build Emacs on GNU/Linux to checkout
> and build this branch and report any problems you see.

It builds on Cygwin (both 32-bit and 64-bit) and appears to run fine.  I tested 
by visiting etc/HELLO, and nothing jumped out at me on visual comparison with 
Emacs built from master.

Ken

Re: Emacs text shaping using Harfbuzz

[Eric Abrahamsen]

Ken Brown <kbrown@cornell.edu> writes:

> On 12/13/2018 10:39 AM, Eli Zaretskii wrote:
>> I'd like to encourage people who build Emacs on GNU/Linux to checkout
>> and build this branch and report any problems you see.
>
> It builds on Cygwin (both 32-bit and 64-bit) and appears to run fine.  I tested 
> by visiting etc/HELLO, and nothing jumped out at me on visual comparison with 
> Emacs built from master.

Likewise on arch linux. Thai and Chinese (the two languages I'm familiar
with) look just fine.

Re: Emacs text shaping using Harfbuzz

[Amin Bandali]

On 2018-12-13  3:23 PM, Eric Abrahamsen wrote:
> Ken Brown <kbrown@cornell.edu> writes:
>
>> On 12/13/2018 10:39 AM, Eli Zaretskii wrote:
>>> I'd like to encourage people who build Emacs on GNU/Linux to checkout
>>> and build this branch and report any problems you see.
>>
>> It builds on Cygwin (both 32-bit and 64-bit) and appears to run fine.  I tested 
>> by visiting etc/HELLO, and nothing jumped out at me on visual comparison with 
>> Emacs built from master.
>
> Likewise on arch linux. Thai and Chinese (the two languages I'm familiar
> with) look just fine.
>

Same goes for Persian and English on my Parabola GNU/Linux-libre setup.

I’d also like to thank everyone on both sides of this collaboration for
working on this.

Re: Emacs text shaping using Harfbuzz

[Eli Zaretskii]

> From: Amin Bandali <bandali@gnu.org>
> Cc: Ken Brown <kbrown@cornell.edu>,  Khaled Hosny <dr.khaled.hosny@gmail.com>,  Ebrahim Byagowi <ebraminio@gmail.com>,  Kenichi Handa <handa@gnu.org>,  John Wiegley <johnw@gnu.org>,  Mohammad Nasirifar <far.nasiri.m@gmail.com>,  "emacs-devel\@gnu.org" <emacs-devel@gnu.org>,  Behdad Esfahbod <behdad@behdad.org>,  Eli Zaretskii <eliz@gnu.org>
> Date: Thu, 13 Dec 2018 19:55:51 -0500
> 
> Same goes for Persian and English on my Parabola GNU/Linux-libre setup.

Thanks for testing.

Re: Emacs text shaping using Harfbuzz

[Basil L. Contovounesios]

Amin Bandali <bandali@gnu.org> writes:

> On 2018-12-13  3:23 PM, Eric Abrahamsen wrote:
>> Ken Brown <kbrown@cornell.edu> writes:
>>
>>> On 12/13/2018 10:39 AM, Eli Zaretskii wrote:
>>>> I'd like to encourage people who build Emacs on GNU/Linux to checkout
>>>> and build this branch and report any problems you see.
>>>
>>> It builds on Cygwin (both 32-bit and 64-bit) and appears to run fine.  I tested 
>>> by visiting etc/HELLO, and nothing jumped out at me on visual comparison with 
>>> Emacs built from master.
>>
>> Likewise on arch linux. Thai and Chinese (the two languages I'm familiar
>> with) look just fine.
>>
>
> Same goes for Persian and English on my Parabola GNU/Linux-libre setup.
>
> I’d also like to thank everyone on both sides of this collaboration for
> working on this.

Sorry if this is getting annoying, but the harfbuzz branch builds on
Debian x86_64 GNU/Linux buster/sid and renders Greek just fine.

Thanks to everyone working on this.

-- 
Basil

Re: Emacs text shaping using Harfbuzz

[Eli Zaretskii]

> From: "Basil L. Contovounesios" <contovob@tcd.ie>
> Date: Fri, 14 Dec 2018 14:40:57 +0000
> Cc: Khaled Hosny <dr.khaled.hosny@gmail.com>,
> 	Ebrahim Byagowi <ebraminio@gmail.com>,
> 	Ken Brown <kbrown@cornell.edu>, Kenichi Handa <handa@gnu.org>,
> 	Eric Abrahamsen <eric@ericabrahamsen.net>, John Wiegley <johnw@gnu.org>,
> 	Mohammad Nasirifar <far.nasiri.m@gmail.com>,
> 	"emacs-devel@gnu.org" <emacs-devel@gnu.org>,
> 	Behdad Esfahbod <behdad@behdad.org>, Eli Zaretskii <eliz@gnu.org>
> 
> Sorry if this is getting annoying

It doesn't.

> the harfbuzz branch builds on Debian x86_64 GNU/Linux buster/sid and
> renders Greek just fine.

Thanks for testing.

Re: Emacs text shaping using Harfbuzz

[Eli Zaretskii]

> From: Eric Abrahamsen <eric@ericabrahamsen.net>
> Cc: Eli Zaretskii <eliz@gnu.org>,  "emacs-devel\@gnu.org" <emacs-devel@gnu.org>,  Khaled Hosny <dr.khaled.hosny@gmail.com>,  Ebrahim Byagowi <ebraminio@gmail.com>,  Behdad Esfahbod <behdad@behdad.org>,  John Wiegley <johnw@gnu.org>,  Mohammad Nasirifar <far.nasiri.m@gmail.com>,  Kenichi Handa <handa@gnu.org>
> Date: Thu, 13 Dec 2018 15:23:55 -0800
> 
> > It builds on Cygwin (both 32-bit and 64-bit) and appears to run fine.  I tested 
> > by visiting etc/HELLO, and nothing jumped out at me on visual comparison with 
> > Emacs built from master.
> 
> Likewise on arch linux. Thai and Chinese (the two languages I'm familiar
> with) look just fine.

Thanks for testing the branch.

Re: Emacs text shaping using Harfbuzz

[Eli Zaretskii]

> From: Ken Brown <kbrown@cornell.edu>
> CC: Khaled Hosny <dr.khaled.hosny@gmail.com>, Ebrahim Byagowi
> 	<ebraminio@gmail.com>, Kenichi Handa <handa@gnu.org>, John Wiegley
> 	<johnw@gnu.org>, Mohammad Nasirifar <far.nasiri.m@gmail.com>, Behdad Esfahbod
> 	<behdad@behdad.org>
> Date: Thu, 13 Dec 2018 21:43:41 +0000
> 
> On 12/13/2018 10:39 AM, Eli Zaretskii wrote:
> > I'd like to encourage people who build Emacs on GNU/Linux to checkout
> > and build this branch and report any problems you see.
> 
> It builds on Cygwin (both 32-bit and 64-bit) and appears to run fine.  I tested 
> by visiting etc/HELLO, and nothing jumped out at me on visual comparison with 
> Emacs built from master.

Thanks for testing.

Re: Emacs text shaping using Harfbuzz

[Florian Beck]

[-- Attachment #1: Type: text/plain, Size: 148 bytes --]

Nice. Build on ubuntu 18.10.

A couple of examples from HELLO (left Harfbuzz, right master). I'm kind 
of suspicious about Burmese and Maldivian.



[-- Attachment #2: burmese.png --]
[-- Type: image/png, Size: 4381 bytes --]

[-- Attachment #3: gujarati.png --]
[-- Type: image/png, Size: 4400 bytes --]

[-- Attachment #4: hindi.png --]
[-- Type: image/png, Size: 4790 bytes --]

[-- Attachment #5: kannada.png --]
[-- Type: image/png, Size: 5316 bytes --]

[-- Attachment #6: lao.png --]
[-- Type: image/png, Size: 5781 bytes --]

[-- Attachment #7: malayalam.png --]
[-- Type: image/png, Size: 5518 bytes --]

[-- Attachment #8: maldivian.png --]
[-- Type: image/png, Size: 5189 bytes --]

[-- Attachment #9: tamil.png --]
[-- Type: image/png, Size: 3788 bytes --]

Re: Emacs text shaping using Harfbuzz

[Kaushal Modi]

[-- Attachment #1: Type: text/plain, Size: 413 bytes --]

On Thu, Dec 13, 2018, 9:12 PM Florian Beck <fb@fbeck.net wrote:

> Nice. Build on ubuntu 18.10.
>
> A couple of examples from HELLO (left Harfbuzz, right master). I'm kind
> of suspicious about Burmese and Maldivian.
>

I know Gujarati and Hindi. The compound glyphs get rendered correctly in
Hindi but not in Gujarati. The discussion on this issue is here:
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=33729

>

[-- Attachment #2: Type: text/html, Size: 967 bytes --]

Re: Emacs text shaping using Harfbuzz

[Eli Zaretskii]

> From: Florian Beck <fb@fbeck.net>
> Date: Fri, 14 Dec 2018 02:11:34 +0100
> 
> A couple of examples from HELLO (left Harfbuzz, right master). I'm kind 
> of suspicious about Burmese and Maldivian.

Thanks for testing, but please report any issues you found using
report-emacs-bug, and please CC on such reports Mohammad Nasirifar
<far.nasiri.m@gmail.com>.

Re: Emacs text shaping using Harfbuzz

[Paul Eggert]

On 12/13/18 11:46 PM, Eli Zaretskii wrote:
>> A couple of examples from HELLO (left Harfbuzz, right master). I'm kind
>> of suspicious about Burmese and Maldivian.
> Thanks for testing, but please report any issues you found using
> report-emacs-bug, and please CC on such reports Mohammad Nasirifar
> <far.nasiri.m@gmail.com>.
>
Good advice for future reports. To try to help out for this particular 
report, I cited it here:

https://bugs.gnu.org/33729#26

and this email was cc'ed to Mohammad. The issues appear to be related to 
Bug#33729 though I'm no expert.

Re: Emacs text shaping using Harfbuzz

[Benjamin Riefenstahl]

Hi all,

Eli Zaretskii writes:
> 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 is very cool, thanks for that.

I compiled and superficially tested the branch, and it generally seems
to work fine.  Is there yet a feature boolean or a frame parameter to
check whether it is enabled?

I will add remarks to the bug reports that already exist about an issue
that I have seen in my test.

benny

Re: Emacs text shaping using Harfbuzz

[Eli Zaretskii]

> From: Benjamin Riefenstahl <b.riefenstahl@turtle-trading.net>
> Cc: emacs-devel@gnu.org,  Khaled Hosny <dr.khaled.hosny@gmail.com>,  Ebrahim Byagowi <ebraminio@gmail.com>,  Kenichi Handa <handa@gnu.org>,  John Wiegley <johnw@gnu.org>,  Mohammad Nasirifar <far.nasiri.m@gmail.com>,  Behdad Esfahbod <behdad@behdad.org>
> Date: Sun, 16 Dec 2018 15:09:16 +0100
> 
> This is very cool, thanks for that.

Thanks for testing the branch.

> Is there yet a feature boolean or a frame parameter to check whether
> it is enabled?

Not yet, this is still very much WIP.  Eventually, I think we should
make Harfbuzz be one of the available font backends, and then you will
be able to see if it's used by looking at frame-parameters.

> I will add remarks to the bug reports that already exist about an issue
> that I have seen in my test.

Thanks.

Re: Emacs text shaping using Harfbuzz

[Mike Kupfer]

Eli Zaretskii wrote:

> I'd like to encourage people who build Emacs on GNU/Linux to checkout
> and build this branch and report any problems you see.

Are reports for other POSIX systems welcome at this time, or would you
rather shake out the issues on GNU/Linux before worrying about other
platforms?

cheers,
mike

Re: Emacs text shaping using Harfbuzz

[Eli Zaretskii]

> From: Mike Kupfer <mkupfer@alum.berkeley.edu>
> cc: emacs-devel@gnu.org, Khaled Hosny <dr.khaled.hosny@gmail.com>,
>         Ebrahim Byagowi <ebraminio@gmail.com>, Kenichi Handa <handa@gnu.org>,
>         John Wiegley <johnw@gnu.org>,
>         Mohammad Nasirifar <far.nasiri.m@gmail.com>,
>         Behdad Esfahbod <behdad@behdad.org>
> Date: Sun, 16 Dec 2018 09:27:23 -0800
> 
> Are reports for other POSIX systems welcome at this time

Of course.  Thanks in advance.