bug#23137: 25.1.50; Subpixel rendering is broken when not running under gnome-session

bug#23137: 25.1.50; Subpixel rendering is broken when not running under gnome-session

[Matthew Leach]

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Hi all,

I sometimes switch between two WMs, namely i3 and GNOME3.  I've noticed
that under GNOME3, the font rendering in Emacs seems to be, in my
opinion, nicer than in i3.  The difference is that under GNOME3 Emacs
uses subpixel rendering and not in i3.

I've tried several configs to get subpixel rendering working in Emacs
under i3: fontconfig and ~/.Xresources (attached).  Unfortunately, Emacs
doesn't conform and still doesn't use subpixel rendering even though
most other applications (gnome-terminal, rhythmbox, firefox, etc...)
do.

I tried running i3 under gnome-session as described at [1] and strangely
this fixes the issue!  Why would running Emacs under gnome-session fix
this?

[1]: http://blog.hugochinchilla.net/2013/03/using-gnome-3-with-i3-window-manager/

In GNU Emacs 25.1.50.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.18.9)
 of 2016-03-24 built on spline
Repository revision: 39577d07124ee16895b9c6aab7e2c6e7d41cc715
Windowing system distributor 'The X.Org Foundation', version 11.0.11802000
Configured using:
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LIBXML2 FREETYPE XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11

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Major mode: Group

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Recent messages:
Opening connection to mx0.mattleach.net via tls...
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Opening nnimap server on Home...done
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-- 
Matt

[-- Attachment #2: .Xresources --]
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Xft.antialias:  1
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Xft.rgba:       rgb

bug#23137: 25.1.50; Subpixel rendering is broken when not running under gnome-session

[Eli Zaretskii]

> From: Matthew Leach <matthew@mattleach.net>
> Date: Mon, 28 Mar 2016 22:16:45 +0100
> 
> I sometimes switch between two WMs, namely i3 and GNOME3.  I've noticed
> that under GNOME3, the font rendering in Emacs seems to be, in my
> opinion, nicer than in i3.  The difference is that under GNOME3 Emacs
> uses subpixel rendering and not in i3.

What is "subpixel rendering"?

bug#23137: 25.1.50; Subpixel rendering is broken when not running under gnome-session

[Matthew Leach]

Hi Eli,

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Matthew Leach <matthew@mattleach.net>
>> Date: Mon, 28 Mar 2016 22:16:45 +0100
>> 
>> I sometimes switch between two WMs, namely i3 and GNOME3.  I've noticed
>> that under GNOME3, the font rendering in Emacs seems to be, in my
>> opinion, nicer than in i3.  The difference is that under GNOME3 Emacs
>> uses subpixel rendering and not in i3.
>
> What is "subpixel rendering"?

[1] gives an overview of what it is and the 'rgba' values in [2] show
how to configure it.  I think MS use the term ClearType on their Windows
platform.

Thanks,
-- 
Matt

[1]: https://en.wikipedia.org/wiki/Subpixel_rendering
[2]: http://linux.die.net/man/5/fonts-conf

bug#23137: 25.1.50; Subpixel rendering is broken when not running under gnome-session

[Eli Zaretskii]

> From: Matthew Leach <matthew@mattleach.net>
> Cc: 23137@debbugs.gnu.org
> Date: Tue, 29 Mar 2016 08:05:20 +0100
> 
> >> I sometimes switch between two WMs, namely i3 and GNOME3.  I've noticed
> >> that under GNOME3, the font rendering in Emacs seems to be, in my
> >> opinion, nicer than in i3.  The difference is that under GNOME3 Emacs
> >> uses subpixel rendering and not in i3.
> >
> > What is "subpixel rendering"?
> 
> [1] gives an overview of what it is and the 'rgba' values in [2] show
> how to configure it.  I think MS use the term ClearType on their Windows
> platform.

Then why do you think it's an Emacs problem?

Are the binaries used on both machines from the same build?  If not,
please show the value of system-configuration-features from both
builds.

Thanks.

bug#23137: 25.1.50; Subpixel rendering is broken when not running under gnome-session

[Matthew Leach]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Matthew Leach <matthew@mattleach.net>
>> Cc: 23137@debbugs.gnu.org
>> Date: Tue, 29 Mar 2016 08:05:20 +0100
>> 
>> >> I sometimes switch between two WMs, namely i3 and GNOME3.  I've noticed
>> >> that under GNOME3, the font rendering in Emacs seems to be, in my
>> >> opinion, nicer than in i3.  The difference is that under GNOME3 Emacs
>> >> uses subpixel rendering and not in i3.
>> >
>> > What is "subpixel rendering"?
>> 
>> [1] gives an overview of what it is and the 'rgba' values in [2] show
>> how to configure it.  I think MS use the term ClearType on their Windows
>> platform.
>
> Then why do you think it's an Emacs problem?

I think it's an Emacs problem, because it is not behaving as configured,
even though other GTK applications do.

> Are the binaries used on both machines from the same build?  

Indeed, it is the same binary on the same machine, I just switch desktop
environments.  If I switch from i3 (an X11 WM) to GNOME3, Emacs uses
subpixel rendering, whereas other packages use it under both scenarios.

> If not, please show the value of system-configuration-features from
> both builds.

The value of this on my machine is:

"XPM JPEG TIFF GIF PNG RSVG SOUND GPM DBUS GSETTINGS NOTIFY ACL GNUTLS
LIBXML2 FREETYPE XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11"

Thanks,
-- 
Matt

bug#23137: 25.1.50; Subpixel rendering is broken when not running under gnome-session

[Eli Zaretskii]

> From: Matthew Leach <matthew@mattleach.net>
> Cc: 23137@debbugs.gnu.org
> Date: Tue, 29 Mar 2016 22:13:14 +0100
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> > What is "subpixel rendering"?
> >> 
> >> [1] gives an overview of what it is and the 'rgba' values in [2] show
> >> how to configure it.  I think MS use the term ClearType on their Windows
> >> platform.
> >
> > Then why do you think it's an Emacs problem?
> 
> I think it's an Emacs problem, because it is not behaving as configured,
> even though other GTK applications do.

What configuration options were supposed to tell Emacs to use subpixel
rendering?

bug#23137: 25.1.50; Subpixel rendering is broken when not running under gnome-session

[Matthew Leach]

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Hi Eli,

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Matthew Leach <matthew@mattleach.net>
>> Cc: 23137@debbugs.gnu.org
>> Date: Tue, 29 Mar 2016 22:13:14 +0100
>> 
>> Eli Zaretskii <eliz@gnu.org> writes:
>> 
>> >> > What is "subpixel rendering"?
>> >> 
>> >> [1] gives an overview of what it is and the 'rgba' values in [2] show
>> >> how to configure it.  I think MS use the term ClearType on their Windows
>> >> platform.
>> >
>> > Then why do you think it's an Emacs problem?
>> 
>> I think it's an Emacs problem, because it is not behaving as configured,
>> even though other GTK applications do.
>
> What configuration options were supposed to tell Emacs to use subpixel
> rendering?

There are two: ~/.Xresources (attached).  On some systems there is
/etc/fonts/conf.avail/10-sub-pixel-*.conf and you can symlink one of
those to /etc/fonts/conf.d (I have attached the one I use).  The 'rgba'
value in both configs controls subpixel rendering.

Thanks,
-- 
Matt

[-- Attachment #2: .Xresources --]
[-- Type: application/octet-stream, Size: 109 bytes --]

Xft.antialias:  1
Xft.hinting:    1
Xft.hintstyle:  hintfull
Xft.lcdfilter:  lcddefault
Xft.rgba:       rgb


[-- Attachment #3: 10-sub-pixel-rgb.conf --]
[-- Type: application/octet-stream, Size: 489 bytes --]

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
<!--  Enable sub-pixel rendering --> 
  <match target="pattern">
    <!--
      This configuration is available on the major desktop environments.
      We shouldn't overwrite it with "assign" unconditionally.
      Most clients may picks up the first value only. so using "append"
      may simply works to avoid it.
    -->
    <edit name="rgba" mode="append"><const>rgb</const></edit>
  </match>
</fontconfig>

bug#23137: 25.1.50; Subpixel rendering is broken when not running under gnome-session

[Wolfgang Jenkner]

On Thu, Mar 31 2016, Matthew Leach wrote:

> On some systems there is
> /etc/fonts/conf.avail/10-sub-pixel-*.conf and you can symlink one of
> those to /etc/fonts/conf.d (I have attached the one I use). 

What about one of 11-lcdfilter-*.conf?

bug#23137: 25.1.50; Subpixel rendering is broken when not running under gnome-session

[Matthew Leach]

Wolfgang Jenkner <wjenkner@inode.at> writes:

> On Thu, Mar 31 2016, Matthew Leach wrote:
>
>> On some systems there is
>> /etc/fonts/conf.avail/10-sub-pixel-*.conf and you can symlink one of
>> those to /etc/fonts/conf.d (I have attached the one I use). 
>
> What about one of 11-lcdfilter-*.conf?

Yes, I forgot about that one, sorry.  I have 11-lcdfilter-default.conf
active on my system.

Thanks,
-- 
Matt

bug#23137: 25.1.50; Subpixel rendering is broken when not running under gnome-session

[Eli Zaretskii]

> From: Matthew Leach <matthew@mattleach.net>
> Cc: 23137@debbugs.gnu.org
> Date: Thu, 31 Mar 2016 08:34:47 +0100
> 
> > What configuration options were supposed to tell Emacs to use subpixel
> > rendering?
> 
> There are two: ~/.Xresources (attached).  On some systems there is
> /etc/fonts/conf.avail/10-sub-pixel-*.conf and you can symlink one of
> those to /etc/fonts/conf.d (I have attached the one I use).  The 'rgba'
> value in both configs controls subpixel rendering.

These are configuration files for software that is external to Emacs,
so I still think the problem might be in the configuration of those
other packages (fontconfig etc.), as I don't think Emacs reads these
files directly.  That's assuming you did make sure that the resources
were read by X.

And I'm really out of my depth here, so if double-checking the setup
of fontconfig and stuff doesn't help, I'm afraid you will have to look
for someone who really knows about this and could help you debug this.
Sorry.

bug#23137: 25.1.50; Subpixel rendering is broken when not running under gnome-session

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> And I'm really out of my depth here, so if double-checking the setup
> of fontconfig and stuff doesn't help, I'm afraid you will have to look
> for someone who really knows about this and could help you debug this.
> Sorry.

(I'm going through old bug reports that unfortunately weren't resolved
at the time.)

Skimming this bug report, I think the conclusion here was that this was
not an Emacs issue, but an OS issue, so I'm closing this bug report.  If
I misunderstood, please respond to the debbugs address and we'll reopen.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#23137: 25.1.50; Subpixel rendering is broken when not running under gnome-session

[Po Lu via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Matthew Leach <matthew@mattleach.net> writes:

> There are two: ~/.Xresources (attached).  On some systems there is
> /etc/fonts/conf.avail/10-sub-pixel-*.conf and you can symlink one of
> those to /etc/fonts/conf.d (I have attached the one I use).  The
> 'rgba' value in both configs controls subpixel rendering.

Firstly, do you still see this problem with Cairo rendering?  Secondly,
please show the output of `xrdb -query'.

Thanks.