Mailinglist Archive: opensuse-bugs (4258 mails)

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[Bug 904015] font aliasing broken under KDE
  • From: bugzilla_noreply@xxxxxxxxxx
  • Date: Thu, 26 Jan 2017 11:11:51 +0000
  • Message-id: <bug-904015-21960-At9PRXgbMB@http.bugzilla.opensuse.org/>
http://bugzilla.opensuse.org/show_bug.cgi?id=904015
http://bugzilla.opensuse.org/show_bug.cgi?id=904015#c30

Marguerite Su <i@xxxxxxxxxxxxx> changed:

What |Removed |Added
----------------------------------------------------------------------------
Status|CONFIRMED |IN_PROGRESS

--- Comment #30 from Marguerite Su <i@xxxxxxxxxxxxx> ---
$ grep -r "Tahoma" fonts.conf_13.2_good (the one the reporter provided in
comment#18)
./usr/share/fontconfig/conf.avail/11-suse-hinting.conf
./usr/share/fontconfig/conf.avail/58-suse-post-user.conf
./usr/share/fontconfig/conf.avail/65-fonts-persian.conf
./usr/share/fontconfig/conf.avail/12-suse-hinting-bc.conf
./usr/share/fontconfig/conf.avail/60-latin.conf
./usr/share/fonts-config/conf.avail/12-suse-hinting-bc.conf
./usr/share/fonts-config/conf.avail/10-group-tt-hinted-fonts.conf

(Everything I said below can be found in "fonts-config"/"fontconfig" packages
in 13.1/13.2 repository on build.opensuse.org)

65-fonts-persian.conf and 60-latin.conf are from fontconfig upstream. there's
no difference between 2.11.0 and 2.11.1

10-group-tt-hinted-fonts.conf is from infinality. it just put fonts into "TT
Instructed Font" category.

58-suse-post-user.conf just disables autohint for Tahoma if its antialias is
disabled. not related to our issue.

12-suse-hinting-bc.conf is from 13.1's fonts-config, it basically does one
thing: disable antialais and autohint for Tahoma if its pixelsize is less than
or equal to 0 (apparently, it means "do nothing").

So the only thing left is 11-suse-hinting.conf, it does the same thing as
12-suse-hinting-bc.conf, but take a look at the beginning:

<!--
Using hinting=true, hintstyle=hintfull and antialias=true
is a good default for most fonts.

Match on "pattern" for the default, not on "font" to make
it easier to override the default using FcPatternDel()
and FcPatternAdd...() (see bugzilla #104365).
-->

<match target="pattern">
<edit name="hinting">
<bool>true</bool>
</edit>
<edit name="antialias">
<bool>true</bool>
</edit>
</match>

In 13.1 (this file is missing from 13.2), it set hinting, antialias to true for
all fonts at first, and tries to disable for those non-fit fonts later.
But as I said, none of the later configurations is able to disable antialias
for Tahoma.

But in 13.2, we let some former self-maintained configurations go.

$ grep -r "antialias" ./usr/share/fonts-config/conf.avail (from fonts-config in
13.2, as I said, no need to research on configurations provided by fontconfig
itself)
./11-base-rendering.conf
./12-tt-monospace-rendering.conf
./13-selective-rendering-ipa.conf
./60-family-prefer.conf

12-tt-monospace-rendering.conf doesn't apply to Tahoma since it's not a
monospace font.

13-selective-rendering-ipa.conf only applies to IPA font which is a Japanese
font.

60-family-prefer.conf has "antialias" inside its comments.

Let's take a look at 11-base-rendering.conf:

<!-- font smooth or don't font smooth -->
<match target="font">
<!-- this test should not be needed,
as antialiasing is done only for outlines,
but workarounds Qt5 issue, see bug 866705 -->
<test name="outline">
<bool>true</bool>
</test>
<edit name="antialias" mode="assign">
<bool>true</bool>
</edit>
</match>

So in 13.2, we only enable antialias for outline fonts. But Tahoma is an
outline font, right?

And I think here's the precise description of the bug:

"Tahoma", an outlined font, didn't get its antialias enabled by fontconfig.


Thanks

Marguerite

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