Font configuration (Italiano)

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Notes: please use the first argument of the template to provide more detailed indications. (Discuss in Talk:Font configuration (Italiano)#)
Summary help replacing me
An overview of font configuration options and various techniques for improving the readability of fonts
Related
Fonts: Information on adding fonts and font recommendations
Java Fonts - Sun JRE: Fonts specific to Sun's Java machine
MS Fonts: Adding Microsoft fonts and mimicking Windows' font settings


Font paths

For fonts to be known to applications, they must be cataloged for easy and quick access. Fontconfig is a library designed to provide a list of available fonts to applications, and also for configuration for how fonts get rendered. Though fontconfig is the standard in today's Linux, some applications still rely on the original method of font categorization: the Xorg server configuration file (Template:Filename).

Fontconfig

Fontconfig gathers all it's configurations in a central file (Template:Filename). Fontconfig-aware applications source this file to know available fonts and how they get rendered. This file is a conglomeration of rules from the various fontconfig configurations (the global configuration (Template:Filename), the configured presets in Template:Filename, and the user configuration file (Template:Filename).

The font paths initially known to fontconfig are: Template:Filename and Template:Filename (of which fontconfig will scan recursively). For ease of organization and installation, it is recommended to use these font paths when installing new fonts.

To see a list of known fontconfig fonts in an easy to read format, type:

fc-list | sed 's,:.*,,' | sort -u

Xorg

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

$ grep /fonts /var/log/Xorg.0.log

Keep in mind that Xorg does not search recursively through the Template:Filename directory like fontconfig does. To add a path, the full path must be used:

Section "Files"
   FontPath     "/usr/share/fonts/example-font-directory"
EndSection

To see a list of known Xorg fonts use Template:Codeline.

Fontconfig configuration

The font rendering packages on Arch Linux includes support for freetype2 with the bytecode interpreter (BCI) enabled. However, defining your own font configuration may at times be necessary. If you have an LCD monitor, consider additionally using the LCD filter packages for better readability.

Configuration can be done either per-user through Template:Filename, or globally with Template:Filename. The settings in the per-user configuration have precedence over the global configuration. Both these files use the same syntax. Remember not to edit the Template:Filename file; it is a temporary file and shouldn't be edited since it's replaced during fontconfig updates.

There are already a number of configured presets in the directory Template:Filename. These presets can be linked to both per-user and globally for quicker configuration. Take note that 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 ~/.fonts.conf.d
$ ln -s /etc/fonts/conf.avail/10-sub-pixel-rgb.conf ~/.fonts.conf.d
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.

Basic settings

The configuration files will need informational headers before settings can be entered:

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

To avoid repetition, the rest of the configuration examples in this article will omit these tags.

Anti-aliasing

Anti-aliasing (aka font rasterization) converts vectors fonts to bitmap for display purposes and in doing so provides a font smoothing effect. Without anti-aliasing (even at higher DPIs) fonts will appear jagged so anti-aliasing is enabled by default.

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

Hinting

Font hinting adjusts the spacing of fonts so that they line up with the pixel grid. Fonts will not line up correctly without hinted until displays have 300 DPI or greater. Two types of hinting are available

To enable normal hinting:

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

Auto-hinting

To enable auto-hinting:

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

Hint style is the amount of influence the hinting mode has. Hinting can be set to: Template:Codeline, Template:Codeline, Template:Codeline (recommended) and Template:Codeline.

  <match target="font">
    <edit name="hintstyle" mode="assign">
      <const>hintslight</const>
    </edit>
  </match>

Subpixel rendering

RGB, BGR, V-RGB (vertical), or V-BGR

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. If you notice unusual colors around font's borders, discover you monitor type here and define it in your font configuration:

  <match target="font">
    <edit name="rgba" mode="assign">
      <const>rgb</const>
    </edit>
  </match>

Like the automatic settings most DE font control panels establish, it is recommended to disable subpixel rendering when using the auto hinter since the combination of the two may result in unsatisfactory rendering.

LCD filter patched packages

Some distributions choose not to use the LCD filter patches for font rendering due to patent ambiguity. If you choose, you can add these patched packages on your own. These patched packages are available in the AUR and easily installable by using an AUR helper. A few considerations:

  • All of these methods are designed for LCD displays but some CRT users may see improvements using the ClearType packages.
  • Configuration is sometimes necessary.
  • The new font effects will not be displayed until the application restarts.

Original LCD packages

These are the vanilla LCD packages and have less pre-configured options and will not have any experimental patches applied.

Remove the conflicting packages:

pacman -Rd libxft cairo

Install the patched packages from the AUR using the AUR helper of your choice. The package names are:

fontconfig-lcd cairo-lcd

Then install the patched packages from the repositories using pacman:

pacman -S libxft-lcd

Ubuntu patched packages

Ubuntu uses the original LCD patched packages and adds extra configurations, and occasionally patches.

First, the conflicting packages need to be removed:

pacman -Rd libxft cairo fontconfig freetype2

Then install the patched packages from the AUR using an AUR helper of your choice. The package names are:

freetype2-ubuntu fontconfig-ubuntu libxft-ubuntu cairo-ubuntu

ClearType packages

Cleartype is a different type of font rendering that is used in Windows systems and is designed to work on both LCD and CRT monitors.

Remove the conflicting packages:

pacman -Rd cairo libxft freetype2

And then install the patched packages from the AUR. Package names:

freetype2-cleartype libxft-cleartype cairo-cleartype

Reverting to original packages

To restore the unpatched packages, first uninstall the patched versions then reinstall the originals:

pacman -S freetype2 libxft cairo

Additional fontconfig configuration

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 auto-hinter 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>
...

Enable anti-aliasing only for bigger fonts

See also sharpfonts.co.cc for related information

Some users prefer the sharper rendering that anti-aliasing doesn't offer:

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

<match target="font" >
    <test name="size" qual="any" compare="more">
        <double>12</double>
    </test>
    <edit name="antialias" mode="assign">
        <bool>true</bool>
    </edit>
</match>

<match target="font" >
    <test name="pixelsize" qual="any" compare="more">
        <double>17</double>
    </test>
    <edit name="antialias" mode="assign">
        <bool>true</bool>
    </edit>
</match>
...

Replace fonts

The most reliable way to do this is to add an XML fragment similar to the one below. This will cause Bitstream Vera Sans to be used in place of Helvetica:

...
<match target="pattern" name="family" >
    <test name="family" qual="any" >
        <string>Helvetica</string>
    </test>
    <edit name="family" mode="assign">
        <string>Bitstream Vera Sans</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>
...

LCD Type

The fontconfig-lcd package by default uses the Template:Codeline (very possible Ubuntu's does too) filter that will work for most users. Other filters are available that can be used in special situations: Template:Codeline; a lighter filter ideal for fonts that look too bold or fuzzy, Template:Codeline, the original Cairo filter; and Template:Codeline to disable it entirely.

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

Disable bitmap fonts

To disable bitmap fonts in fontconfig, use Template:Filename (which is not placed by fontconfig by default):

# rm /etc/fonts/conf.d/70-yes-bitmaps.conf  
# ln -s /etc/fonts/conf.avail/70-no-bitmaps.conf /etc/fonts/conf.d

Depending on the type of fontconfig you are using (default, or -lcd patched) you can choose which fonts to replace bitmaps fonts with (Helvetica, Courier and Times bitmap mapts to TTF fonts) by:

# ln -s /etc/conf.avail/29-replace-bitmap-fonts.conf /etc/fonts/conf.d

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 Template:Filename as explained below. Store a copy of the modifications on another file, because a font update with Template:Codeline will overwrite Template:Filename.

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 Template:Codeline to Template:Codeline or any other style. Also change Template:Codeline to Template:Codeline for italic, Template:Codeline to Template:Codeline 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 Template:Filename:

...
<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

Fontconfig processes files in Template:Filename in reverse 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 00-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.

Example fontconfig configurations

Example fontconfig configurations can be found on this page.

Troubleshooting

Ubuntu-patched fonts

Edits to improve Ubuntu lcd-patched fonts.

Blurry fonts after install

The Ubuntu fontconfig by default doesn't set sub-pixel rendering in it's global configuration. I'm not sure why exactly, I've noticed the same configurations in Template:Filename as when I've loaded and Ubuntu CD but my Ubuntu fonts have always looked blurry after the install. Perhaps it's because I'm using a different desktop environment than Gnome, but to fix this I've always had to set my sub-pixel rendering type on:

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

Then logout and back in again.

Distorted fonts

Main article: Xorg#Display size and DPI

Fontconfig should be able to detect DPI parameters as discovered by the Xorg server and be able to display the fonts correctly. Those having problems can still fall back to setting it manually:

...
<match target="pattern">
   <edit name="dpi" mode="assign"><double>96</double></edit>
</match>
...

If fonts are still unexpectedly large or small, or are poorly proportioned, the Xorg server may be incorrectly detecting the DPI setting.

Missing characters

If using Emacs, the Template:Package Official and Template:Package Official packages need to be installed.

Older GTK and QT applications

Modern GTK apps enable Xft by default but this was not the case before version 2.2. If it is not possible to update these applications, force Xft for old GNOME applications by adding to Template:Filename:

export GDK_USE_XFT=1

For older QT applications:

export QT_XFT=true

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