Comment # 56 on bug 904015 from Petr Gajdos

Indeed, looks like a user setting problem.

Here you are:

(In reply to Vadim Krevs from comment #55)
> <?xml version='1.0'?>
> <!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>
> <fontconfig>
>  <match target="font">

Turn on autohint for every font.

>   <edit mode="assign" name="autohint">
>    <bool>true</bool>
>   </edit>
>  </match>
>  <match target="font">
>   <test compare="more" name="weight">
>    <const>medium</const>
>   </test>
>   <edit mode="assign" name="autohint">
>    <bool>false</bool>
>   </edit>

Do not force autohint, for _every_font_, for weight >= demibold for whatever
reason.

>  </match>
>  <match target="font">
>   <test name="family">
>    <string>Tahoma</string>
>    <string>Andale Mono</string>
>    <string>Arial</string>
>    <string>Comic Sans MS</string>
>    <string>Georgia</string>
>    <string>Impact</string>
>    <string>Trebuchet MS</string>
>    <string>Verdana</string>
>    <string>Courier New</string>
>    <string>Times New Roman</string>
>    <string>Webdings</string>
>    <string>Albany AMT</string>
>    <string>Thorndale AMT</string>
>    <string>Cumberland AMT</string>
>    <string>Andale Sans</string>
>    <string>Andy MT</string>
>    <string>Bell MT</string>
>    <string>Monotype Sorts</string>
>   </test>
>   <!--  
>   <test name="antialias">
>    <bool>false</bool>
>   </test>
> -->
>   <test compare="more_eq" name="size" qual="any">
>    <double>0</double>
>   </test>
>   <test compare="less_eq" name="size" qual="any">
>    <double>9</double>
>   </test>
>   <edit name="autohint">
>    <bool>false</bool>
>   </edit>

Do not force autohint for smaller sizes for certain font families. 

>   <edit mode="assign" name="antialias">
>    <bool>false</bool>
>   </edit>
>  </match>
>  <match target="font">
>   <edit mode="assign" name="rgba">
>    <const>rgb</const>
>   </edit>
>  </match>
>  <dir>~/.fonts</dir>
>  <match target="font">
>   <edit mode="assign" name="hinting">
>    <bool>true</bool>
>   </edit>
>  </match>
>  <match target="font">
>   <edit mode="assign" name="hintstyle">
>    <const>hintfull</const>
>   </edit>
>  </match>
>  <match target="font">
>   <edit mode="assign" name="antialias">
>    <bool>true</bool>
>   </edit>
>  </match>
>  <match target="font">
>   <test compare="more_eq" name="size" qual="any">
>    <double>0</double>
>   </test>
>   <test compare="less_eq" name="size" qual="any">
>    <double>8</double>
>   </test>
>   <edit mode="assign" name="antialias">
>    <bool>false</bool>
>   </edit>
>  </match>
>  <match target="font">
>   <test compare="more_eq" name="pixelsize" qual="any">
>    <double>0</double>
>   </test>
>   <test compare="less_eq" name="pixelsize" qual="any">
>    <double>11</double>
>   </test>
>   <edit mode="assign" name="antialias">
>    <bool>false</bool>
>   </edit>
>  </match>
> </fontconfig>

All in all, autohint is forced for all fonts with weight <= medium and size,
even for Tahoma and others listed in the long match which should not. Also
antialias is set to false for certain families/sizes, then it is set to true
for all fonts and again set to false for all fonts for certain sizes.

Also following warning should not be overlooked:

> Fontconfig warning: "/home/vadymk/.config/fontconfig/fonts.conf", line 37: 
> Having multiple values in <test> isn't supported and may not work as expected

It is evident that the file was written by more entities. I guess you have two
possibilities after backuping and removing this file:

1. rely on distro setting: we do not support for excluding ranges from
antialias though [in fonts-config and/or yast2-fonts, I will consider to add it
at least for fonts-config, for yast2-fonts it won't be trivial and even include
libfontspecimen changes], so you need to add to your
~/.config/fontsconfig/fonts.conf:

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
  <match target="font">
    <test name="font_type">
      <string>TT Instructed Font</string>
    </test>
    <test name="size" compare="less_eq">
      <double>8.0</double>
    </test>
    <edit name="antialias">
      <bool>false</bool>
    </edit>
  </match>
</fontconfig>

Do not use KDE font setting afterwards, without removing the file again.

2. rely on settings written by KDE: After backuping and removing
/home/vadymk/.config/fontconfig/fonts.conf, KDE should write a new one.