Font configuration

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Fontconfig is a library designed to provide a list of available fonts to applications, and also for configuration for how fonts get rendered: see Wikipedia:Fontconfig. The FreeType library freetype2 renders the fonts, based on this configuration.

Though Fontconfig is the standard in modern Linux, some applications rely on the original method of font selection and display, the X Logical Font Description.

The font rendering packages on Arch Linux includes support for freetype2 with the bytecode interpreter (BCI) enabled. For better font rendering, especially with an LCD monitor, see #Fontconfig configuration and Font configuration/Examples.

Font paths

For fonts to be known to applications, they must be cataloged for easy and quick access.

The font paths initially known to Fontconfig are: /usr/share/fonts/, ~/.local/share/fonts (and ~/.fonts/, now deprecated). Fontconfig will scan these directories recursively. For ease of organization and installation, it is recommended to use these font paths when adding fonts.

To see a list of known Fontconfig fonts:

$ fc-list : file

See man fc-list for more output formats.

Check for Xorg's known font paths by reviewing its log:

$ grep /fonts ~/.local/share/xorg/Xorg.0.log
Tip:
  • You can also check the list of Xorg's known font paths using the command xset q.
  • Use /var/log/Xorg.0.log if Xorg is run with root privileges.

Keep in mind that Xorg does not search recursively through the /usr/share/fonts/ directory like Fontconfig does. To add a path, the full path must be used:

Section "Files"
    FontPath     "/usr/share/fonts/local/"
EndSection

If you want font paths to be set on a per-user basis, you can add and remove font paths from the default by adding the following line(s) to ~/.xinitrc:

xset +fp /usr/share/fonts/local/           # Prepend a custom font path to Xorg's list of known font paths
xset -fp /usr/share/fonts/sucky_fonts/     # Remove the specified font path from Xorg's list of known font paths

To see a list of known Xorg fonts use xlsfonts, from the xorg-xlsfonts package.

Fontconfig configuration

Fontconfig is documented in the fonts-conf man page.

Configuration can be done per-user through $XDG_CONFIG_HOME/fontconfig/fonts.conf, and globally with /etc/fonts/local.conf. The settings in the per-user configuration have precedence over the global configuration. Both these files use the same syntax.

Note: Configuration files and directories: ~/.fonts.conf/, ~/.fonts.conf.d/ and ~/.fontconfig/*.cache-* are deprecated since fontconfig 2.10.1 (upstream commit) and will not be read by default in the future versions of the package. New paths are $XDG_CONFIG_HOME/fontconfig/fonts.conf, $XDG_CONFIG_HOME/fontconfig/conf.d/NN-name.conf and $XDG_CACHE_HOME/fontconfig/*.cache-* respectively. If using the second location, make sure the naming is valid (where NN is a two digit number like 00, 10, or 99).

Fontconfig gathers all its configurations in a central file (/etc/fonts/fonts.conf). This file is replaced during fontconfig updates and should not be edited. Fontconfig-aware applications source this file to know available fonts and how they get rendered. This file is a conglomeration of rules from the global configuration (/etc/fonts/local.conf), the configured presets in /etc/fonts/conf.d/, and the user configuration file ($XDG_CONFIG_HOME/fontconfig/fonts.conf). fc-cache can be used to rebuild fontconfig's configuration, although changes will only be visible in newly launched applications.

Note: For some desktop environments (such as GNOME and KDE) using the Font Control Panel will automatically create or overwrite the user font configuration file. For these desktop environments, it is best to match your already defined font configurations to get the expected behavior.

Fontconfig configuration files use XML format and need these headers:

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>

  <!-- settings go here -->

</fontconfig>

The configuration examples in this article omit these tags.

Presets

There are presets installed in the directory /etc/fonts/conf.avail. They can be enabled by creating symbolic links to them, both per-user and globally, as described in /etc/fonts/conf.d/README. These presets will override matching settings in their respective configuration files.

For example, to enable sub-pixel RGB rendering globally:

# cd /etc/fonts/conf.d
# ln -s ../conf.avail/10-sub-pixel-rgb.conf

To do the same but instead for a per-user configuration:

$ mkdir $XDG_CONFIG_HOME/fontconfig/conf.d
$ ln -s /etc/fonts/conf.avail/10-sub-pixel-rgb.conf $XDG_CONFIG_HOME/fontconfig/conf.d

Anti-aliasing

Font rasterization converts vector font data to bitmap data so that it can be displayed. The result can appear jagged due to aliasing. Technique known as anti-aliasing can be used to increase the apparent resolution of font edges. Anti-aliasing is enabled by default. To disable it:

  <match target="font">
    <edit name="antialias" mode="assign">
      <bool>false</bool>
    </edit>
  </match>
Note: Some applications, like GNOME may override default anti-aliasing settings.

Hinting

Font hinting (also known as instructing) is the use of mathematical instructions to adjust the display of an outline font so that it lines up with a rasterized grid, (i.e. the pixel grid of the display). Its intended effect is to make fonts appear more crisp so that they are more readable. Fonts will line up correctly without hinting when displays have around 300 DPI.

Byte-Code Interpreter (BCI)

Using BCI hinting, instructions in TrueType fonts are rendered according to FreeTypes's interpreter. BCI hinting works well with fonts with good hinting instructions. Hinting is enabled by default. To disable it:

  <match target="font">
    <edit name="hinting" mode="assign">
      <bool>false</bool>
    </edit>
  </match>

Autohinter

The autohinter attempts to do automatic hinting and disregards any existing hinting information. Originally it was the default because TrueType2 fonts were patent-protected but now that these patents have expired there is very little reason to use it. It does work better with fonts that have broken or no hinting information but it will be strongly sub-optimal for fonts with good hinting information. Generally common fonts are of the later kind so autohinter will not be useful. Autohinter is disabled by default. To enable it:

  <match target="font">
    <edit name="autohint" mode="assign">
      <bool>true</bool>
    </edit>
  </match>

Hintstyle

Hintstyle is the amount of font reshaping done to line up to the grid. Hinting values are: hintnone, hintslight, hintmedium, and hintfull. hintslight will make the font more fuzzy to line up to the grid but will be better in retaining font shape, while hintfull will be a crisp font that aligns well to the pixel grid but will lose a greater amount of font shape. hintslight is the default setting. To change it:

  <match target="font">
    <edit name="hintstyle" mode="assign">
      <const>hintnone</const>
    </edit>
  </match>
Note: Some applications, like GNOME may override default hinting settings.

Subpixel rendering

Most monitors manufactured today use the Red, Green, Blue (RGB) specification. Fontconfig will need to know your monitor type to be able to display your fonts correctly. Monitors are either: RGB (most common), BGR, V-RGB (vertical), or V-BGR. A monitor test can be found here.

To enable subpixel rendering:

  <match target="font">
    <edit name="rgba" mode="assign">
      <const>rgb</const>
    </edit>
  </match>
Note: Subpixel rendering effectively triples the horizontal (or vertical) resolution for fonts by making use of subpixels. The default autohinter and subpixel rendering are not designed to work together, hence you will want to enable the subpixel autohinter by Infinality, et al. Freetype2 is compiled with the TT_CONFIG_OPTION_SUBPIXEL_HINTING macro. However, it must be enabled by setting the FT2_SUBPIXEL_HINTING environment variable to any value.FS#35274

LCD filter

When using subpixel rendering, you should enable the LCD filter, which is designed to reduce colour fringing. This is described under LCD filtering in the FreeType 2 API reference. Different options are described under FT_LcdFilter, and are illustrated by this LCD filter test page.

The lcddefault filter will work for most users. Other filters are available that can be used in special situations: lcdlight; a lighter filter ideal for fonts that look too bold or fuzzy, lcdlegacy, the original Cairo filter; and lcdnone to disable it entirely.

  <match target="font">
    <edit name="lcdfilter" mode="assign">
      <const>lcddefault</const>
    </edit>
  </match>

Advanced LCD filter specification

If the available, built-in LCD filters are not satisfactory, it is possible to tweak the font rendering very specifically by building a custom freetype2 package and modifying the hardcoded filters. The Arch Build System can be used to build and install packages from source.

Tip: With the Infinality packages, the LCD filter can be modified without rebuilds.

First, refresh the freetype2 PKGBUILD as root:

# abs extra/freetype2

This example uses /var/abs/build as the build directory, substitute it according to your personal ABS setup. Download and extract the freetype2 package as a regular user:

$ cd /var/abs/build
$ cp -r ../extra/freetype2 .
$ cd freetype2
$ makepkg -o

Edit the file src/freetype-VERSION/src/base/ftlcdfil.c and look up the definition of the constant default_filter[5]:

static const FT_Byte  default_filter[5] =
    { 0x10, 0x40, 0x70, 0x40, 0x10 };

This constant defines a low-pass filter applied to the rendered glyph. Modify it as needed. Save the file, build and install the custom package:

$ makepkg -e
# pacman -Rd freetype2
# pacman -U freetype2-VERSION-ARCH.pkg.tar.xz

Reboot or restart X. The lcddefault filter should now render fonts differently.

Disable auto-hinter for bold fonts

The auto-hinter uses sophisticated methods for font rendering, but often makes bold fonts too wide. Fortunately, a solution can be turning off the autohinter for bold fonts while leaving it on for the rest:

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

Replace or set default fonts

The most reliable way to do this is to add an XML fragment similar to the one below. Using the "binding" attribute will give you better results, for example, in Firefox where you may not want to change properties of font being replaced. This will cause Ubuntu to be used in place of Georgia:

...
 <match target="pattern">
   <test qual="any" name="family"><string>georgia</string></test>
   <edit name="family" mode="assign" binding="same"><string>Ubuntu</string></edit>
 </match>
...

An alternate approach is to set the "preferred" font, but this only works if the original font is not on the system, in which case the one specified will be substituted:

...
<!-- Replace Helvetica with Bitstream Vera Sans Mono -->
<!-- Note, an alias for Helvetica should already exist in default conf files -->
<alias>
    <family>Helvetica</family>
    <prefer><family>Bitstream Vera Sans Mono</family></prefer>
    <default><family>fixed</family></default>
</alias>
...

Whitelisting and blacklisting fonts

The element <selectfont> is used in conjunction with the <acceptfont> and <rejectfont> elements to selectively whitelist or blacklist fonts from the resolve list and match requests. The simplest and most typical use case it to reject one font that is needed to be installed, however is getting matched for a generic font query that is causing problems within application user interfaces.

First obtain the Family name as listed in the font itself:

$ fc-scan .fonts/lklug.ttf --format='%{family}\n'
LKLUG

Then use that Family name in a <rejectfont> stanza:

<selectfont>
    <rejectfont>
        <pattern>
            <patelt name="family" >
                <string>LKLUG</string>
            </patelt>
        </pattern>
    </rejectfont>
</selectfont>

Typically when both elements are combined, <rejectfont> is first used on a more general matching glob to reject a large group (such as a whole directory), then <acceptfont> is used after it to whitelist individual fonts out of the larger blacklisted group.

<selectfont>
    <rejectfont>
        <glob>/usr/share/fonts/OTF/*</glob>
    </rejectfont>
    <acceptfont>
        <pattern>
            <patelt name="family" >
                <string>Monaco</string>
            </patelt>
        </pattern>
    </acceptfont>
</selectfont>

Disable bitmap fonts

Bitmap fonts are sometimes used as fallbacks for missing fonts, which may cause text to be rendered pixelated or too large. Use the 70-no-bitmaps.conf preset to disable this behavior.

To disable embedded bitmap for all fonts:
~/.config/fontconfig/conf.d/20-no-embedded.conf
<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
  <match target="font">
    <edit name="embeddedbitmap" mode="assign">
      <bool>false</bool>
    </edit>
  </match>
</fontconfig>

To disable embedded bitmap fonts for a specific font:

<match target="font">
  <test qual="any" name="family">
    <string>Monaco</string>
  </test>
  <edit name="embeddedbitmap"><bool>false</bool></edit>
</match>

Disable scaling of bitmap fonts

To disable scaling of bitmap fonts (which often makes them blurry), remove /etc/fonts/conf.d/10-scale-bitmap-fonts.conf.

Create bold and italic styles for incomplete fonts

FreeType has the ability to automatically create italic and bold styles for fonts that do not have them, but only if explicitly required by the application. Given programs rarely send these requests, this section covers manually forcing generation of missing styles.

Start by editing /usr/share/fonts/fonts.cache-1 as explained below. Store a copy of the modifications on another file, because a font update with fc-cache will overwrite /usr/share/fonts/fonts.cache-1.

Assuming the Dupree font is installed:

"dupree.ttf" 0 "Dupree:style=Regular:slant=0:weight=80:width=100:foundry=unknown:index=0:outline=True:etc...

Duplicate the line, change style=Regular to style=Bold or any other style. Also change slant=0 to slant=100 for italic, weight=80 to weight=200 for bold, or combine them for bold italic:

"dupree.ttf" 0 "Dupree:style=Bold Italic:slant=100:weight=200:width=100:foundry=unknown:index=0:outline=True:etc...

Now add necessary modifications to $XDG_CONFIG_HOME/fontconfig/fonts.conf:

...
<match target="font">
    <test name="family" qual="any">
        <string>Dupree</string>
         <!-- other fonts here .... -->
     </test>
     <test name="weight" compare="more_eq"><int>140</int></test>
     <edit name="embolden" mode="assign"><bool>true</bool></edit>
</match>

<match target="font">
    <test name="family" qual="any">
        <string>Dupree</string>
        <!-- other fonts here .... -->
    </test>
    <test name="slant" compare="more_eq"><int>80</int></test>
    <edit name="matrix" mode="assign">
        <times>
            <name>matrix</name>
                <matrix>
                    <double>1</double><double>0.2</double>
                    <double>0</double><double>1</double>
                </matrix>
        </times>
    </edit>
</match>
...
Tip: Use the value 'embolden' for existing bold fonts in order to make them even bolder.

Change rule overriding

Tango-inaccurate.pngThe factual accuracy of this article or section is disputed.Tango-inaccurate.png

Reason: /etc/fonts/conf.d/50-user.conf will be created again when fontconfig is updated (Discuss in Talk:Font configuration#)

Fontconfig processes files in /etc/fonts/conf.d in numerical order. This enables rules or files to override one another, but often confuses users about what file gets parsed last.

To guarantee that personal settings take precedence over any other rules, change their ordering:

# cd /etc/fonts/conf.d
# mv 50-user.conf 99-user.conf

This change seems however to be unnecessary for the most of the cases, because a user is given enough control by default to set up own font preferences, hinting and antialiasing properties, alias new fonts to generic font families, etc.

Query the current settings

To find out what settings are in effect, use fc-match --verbose. eg.

$ fc-match --verbose Sans
family: "DejaVu Sans"(s)
hintstyle: 3(i)(s)
hinting: True(s)
...

Look up the meaning of the numbers at http://www.freedesktop.org/software/fontconfig/fontconfig-user.html. Eg. 'hintstyle: 3' means 'hintfull'

Applications without fontconfig support

Some applications like URxvt will ignore fontconfig settings. You can work around this by using ~/.Xresources, but it is as flexible as fontconfig. Example (see #Fontconfig configuration for explanations of the options):

~/.Xresources
Xft.autohint: 0
Xft.lcdfilter:  lcddefault
Xft.hintstyle:  hintslight
Xft.hinting: 1
Xft.antialias: 1
Xft.rgba: rgb

Make sure the settings are loaded properly when X starts with xrdb -q (see Xresources for more information).

Troubleshooting

Distorted fonts

Note: 96 DPI is not a standard. You should use your monitor's actual DPI to get proper font rendering, especially when using subpixel rendering.

If fonts are still unexpectedly large or small, poorly proportioned or simply rendering poorly, fontconfig may be using the incorrect DPI.

Fontconfig should be able to detect DPI parameters as discovered by the Xorg server. You can check the automatically discovered DPI with xdpyinfo (provided by the xorg-xdpyinfo package):

$ xdpyinfo | grep dots
  resolution:    102x102 dots per inch

If the DPI is detected incorrectly (usually due to an incorrect monitor EDID), you can specify it manually in the Xorg configuration, see Xorg#Display size and DPI. This is the recommended solution, but it may not work with buggy drivers.

Fontconfig will default to the Xft.dpi variable if it is set. Xft.dpi is usually set by desktop environments (usually to Xorg's DPI setting) or manually in ~/.Xdefaults or ~/.Xresources. Use xrdb to query for the value:

$ xrdb -query | grep dpi
Xft.dpi:	102

Those still having problems can fall back to manually setting the DPI used by fontconfig:

...
<match target="pattern">
   <edit name="dpi" mode="assign"><double>102</double></edit>
</match>
...

Calibri, Cambria, Monaco, etc. not rendering properly

Some scalable fonts have embedded bitmap versions which are rendered instead, mainly at smaller sizes. Using Metric-compatible fonts as replacements can improve the rendering in these cases.

You can also force using scalable fonts at all sizes by #Disabling embedded bitmap, sacrificing some rendering quality.

Applications overriding hinting

Some applications or desktop environments may override default fontconfig hinting and anti-aliasing settings. This may happen with GNOME 3, for example while you are using Qt applications like vlc or smplayer. Use the specific configuration program for the application in such cases. For GNOME, try gnome-tweak-tool.

Applications not picking up hinting from DE's settings

For instance, under GNOME it sometimes happens that Firefox applies full hinting even when it's set to "none" in GNOME's settings, which results in sharp and widened fonts. In this case you would have to add hinting settings to your fonts.conf file:

<?xml version='1.0'?>
<!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>	
<fontconfig>
 <match target="font">
  <edit mode="assign" name="hinting">
   <bool>false</bool>
  </edit>
 </match>
</fontconfig>

In this example, hinting is set to "grayscale".

Incorrect hinting in GTK applications on non-Gnome systems

Tango-inaccurate.pngThe factual accuracy of this article or section is disputed.Tango-inaccurate.png

Reason: Mentions GTK relies on fontconfig, then claims that "some" fonts get the hinting "wrong", and ends up refering to Xft (but see e.g [1]). IOW, unsupported claims and unclear relations (Discuss in Talk:Font configuration#)
GNOME uses the XSETTINGS system to configure font rendering. Without gnome-settings-daemon, GTK applications rely on fontconfig, but some fonts get the hinting wrong causing them to look too bold or too light.

A simple solution is using xsettingsd-gitAUR as a replacement for gnome-settings-daemon to provide the configuration, for example:

~/.xsettingsd
Xft/Hinting 1
Xft/RGBA "rgb"
Xft/HintStyle "hintslight"
Xft/Antialias 1

Alternatively you could just write the font configuration as Xft.* directives in ~/.Xresources without using a settings daemon.

Font problem in Generated PDFs

If the following command

fc-match helvetica

produces

helvR12-ISO8859-1.pcf.gz: "Helvetica" "Regular"

then the bitmap font provided by xorg-fonts-75dpi is likely to be embedded into PDFs generated by "Print to File" or "Export" in various applications. The bitmap font was probably installed as a consequence of installing the whole xorg group (which is usually NOT recommended). To solve the pixelized font problem, you can uninstall the package. Install gsfonts (Type 1) or tex-gyre-fonts (OpenType) for corresponding free subsitute of Helvetica (and other PostScript/PDF base fonts).

You may also experience similar problem when you open a PDF which requires Helvetica but does not have it embedded for viewing.

See also