25 Graphical user interface #

To get an overview about which fonts are installed on your system, ask the commands rpm or fc-list. Both will give you a good answer, but may return a different list depending on system and user configuration:

If you want to know what an installed font family looks like, either use the command ftview (package ft2demos) or visit https://fontinfo.opensuse.org/. For example, to display the FreeMono font in 14 point, use ftview like this:

> ftview 14 /usr/share/fonts/truetype/FreeMono.ttf

If you need further information, go to https://fontinfo.opensuse.org/ to find out which styles (regular, bold, italic, etc.) and languages are supported.

To query which font is used when a pattern is given, use the fc-match command.

For example, if your pattern contains an already installed font, fc-match returns the file name, font family, and the style:

> fc-match 'Liberation Serif'
LiberationSerif-Regular.ttf: "Liberation Serif" "Regular"

If the desired font does not exist on your system, Fontconfig's matching rules take place and try to find the most similar fonts available. This means, your request is substituted:

> fc-match 'Foo Family'
DejaVuSans.ttf: "DejaVu Sans" "Book"

Fontconfig supports aliases: a name is substituted with another family name. A typical example are the generic names such as “sans-serif”, “serif”, and “monospace”. These alias names can be substituted by real family names or even a preference list of family names:

> for font in serif sans mono; do fc-match "$font" ; done
DejaVuSerif.ttf: "DejaVu Serif" "Book"
DejaVuSans.ttf: "DejaVu Sans" "Book"
DejaVuSansMono.ttf: "DejaVu Sans Mono" "Book"

The result may vary on your system, depending on which fonts are currently installed.

Note: Similarity rules according to fontconfig

Fontconfig always returns a real family (if at least one is installed) according to the given request, as similar as possible. “Similarity” depends on Fontconfig's internal metrics and on the user's or administrator's Fontconfig settings.

To install a new font there are these major methods:

Depending on the rendering medium, and font size, the result may be unsatisfactory. For example, an average monitor these days has a resolution of 100dpi which makes pixels too big and glyphs look clunky.

There are several algorithms available to deal with low resolutions, such as anti-aliasing (grayscale smoothing), hinting (fitting to the grid), or subpixel rendering (tripling resolution in one direction). These algorithms can also differ from one font format to another.

Via Fontconfig, it is possible to select a rendering algorithms for every font individually or for a set of fonts.

> sudo /usr/sbin/fonts-config

25.2.5.2 Diving into fontconfig XML #

  

Fontconfig's configuration format is the eXtensible Markup Language (XML). These few examples are not a complete reference, but a brief overview. Details and other inspiration can be found in man 5 fonts-conf or in /etc/fonts/conf.d/.

The central Fontconfig configuration file is /etc/fonts/fonts.conf, which—along other work—includes the whole /etc/fonts/conf.d/ directory. To customize Fontconfig, there are two places where you can insert your changes:

Fontconfig configuration files #

  

1. System-wide changes.  Edit the file /etc/fonts/local.conf (by default, it contains an empty fontconfig element).

2. User-specific changes.  Edit the file ~/.config/fontconfig/fonts.conf. Place Fontconfig configuration files in the ~/.config/fontconfig/conf.d/ directory.

User-specific changes overwrite any system-wide settings.

Note: Deprecated user configuration file

The file ~/.fonts.conf is marked as deprecated and should not be used anymore. Use ~/.config/fontconfig/fonts.conf instead.

Every configuration file needs to have a fontconfig element. As such, the minimal file looks like this:

<?xml version="1.0"?>
   <!DOCTYPE fontconfig SYSTEM "fonts.dtd">
   <fontconfig>
   <!-- Insert your changes here -->
   </fontconfig>

If the default directories are not enough, insert the dir element with the respective directory:

<dir>/usr/share/fonts2</dir>

Fontconfig searches recursively for fonts.

Font-rendering algorithms can be chosen with following Fontconfig snippet (see Example 25.1, “Specifying rendering algorithms”):

Example 25.1: Specifying rendering algorithms #

  

<match target="font">
 <test name="family">
  <string>FAMILY_NAME</string>
 </test>
 <edit name="antialias" mode="assign">
  <bool>true</bool>
 </edit>
 <edit name="hinting" mode="assign">
  <bool>true</bool>
 </edit>
 <edit name="autohint" mode="assign">
  <bool>false</bool>
 </edit>
 <edit name="hintstyle" mode="assign">
  <const>hintfull</const>
 </edit>
</match>

Various properties of fonts can be tested. For example, the <test> element can test for the font family (as shown in the example), size interval, spacing, font format, and others. When abandoning <test> completely, all <edit> elements will be applied to every font (global change).

Example 25.2: Aliases and family name substitutions #

  

Rule 1

<alias>
 <family>Alegreya SC</family>
 <default>
  <family>serif</family>
 </default>
</alias>

Rule 2

<alias>
 <family>serif</family>
 <prefer>
  <family>Droid Serif</family>
 </prefer>
</alias>

Rule 3

<alias>
 <family>serif</family>
 <accept>
  <family>STIXGeneral</family>
 </accept>
</alias>

The rules from Example 25.2, “Aliases and family name substitutions” create a prioritized family list (PFL). Depending on the element, different actions are performed:

<default> from Rule 1

This rule adds a serif family name at the end of the PFL.

<prefer> from Rule 2

This rule adds “Droid Serif” just before the first occurrence of serif in the PFL, whenever Alegreya SC is in PFL.

<accept> from Rule 3

This rule adds a “STIXGeneral” family name just after the first occurrence of the serif family name in the PFL.

Putting this together, when snippets occur in the order Rule 1 - Rule 2 - Rule 3 and the user requests “Alegreya SC”, then the PFL is created as depicted in Table 25.1, “Generating PFL from fontconfig rules”.

Table 25.1: Generating PFL from fontconfig rules #

  

Order	Current PFL
Request	Alegreya SC
Rule 1	Alegreya SC, serif
Rule 2	Alegreya SC, Droid Serif, serif
Rule 3	Alegreya SC, Droid Serif, serif, STIXGeneral

In Fontconfig's metrics, the family name has the highest priority over other patterns, like style, size, etc. Fontconfig checks which family is currently installed on the system. If “Alegreya SC” is installed, then Fontconfig returns it. If not, it asks for “Droid Serif”, etc.

Be careful. When the order of Fontconfig snippets is changed, Fontconfig can return different results, as depicted in Table 25.2, “Results from generating PFL from fontconfig rules with changed order”.

Table 25.2: Results from generating PFL from fontconfig rules with changed order #

  

Order	Current PFL	Note
Request	Alegreya SC	Same request performed.
Rule 2	Alegreya SC	serif not in PFL, nothing is substituted
Rule 3	Alegreya SC	serif not in PFL, nothing is substituted
Rule 1	Alegreya SC, serif	Alegreya SC present in PFL, substitution is performed

Note: Implication

Think of the <default> alias as a classification or inclusion of this group (if not installed). As the example shows, <default> should always precede the <prefer> and <accept> aliases of that group.

<default> classification is not limited to the generic aliases serif, sans-serif and monospace. See /usr/share/fontconfig/conf.avail/30-metric-aliases.conf for a complex example.

The following Fontconfig snippet in Example 25.3, “Aliases and family name substitutions” creates a serif group. Every family in this group could substitute others when a former font is not installed.

Example 25.3: Aliases and family name substitutions #

  

<alias>
 <family>Alegreya SC</family>
 <default>
  <family>serif</family>
 </default>
</alias>
<alias>
 <family>Droid Serif</family>
 <default>
  <family>serif</family>
 </default>
</alias>
<alias>
 <family>STIXGeneral</family>
 <default>
  <family>serif</family>
 </default>
</alias>
<alias>
 <family>serif</family>
 <accept>
  <family>Droid Serif</family>
  <family>STIXGeneral</family>
  <family>Alegreya SC</family>
 </accept>
</alias>

Priority is given by the order in the <accept> alias. Similarly, stronger <prefer> aliases can be used.

Example 25.2, “Aliases and family name substitutions” is expanded by Example 25.4, “Aliases and family names substitutions”.

Example 25.4: Aliases and family names substitutions #

  

Rule 4

<alias>
 <family>serif</family>
 <accept>
  <family>Liberation Serif</family>
 </accept>
</alias>

Rule 5

<alias>
 <family>serif</family>
 <prefer>
  <family>DejaVu Serif</family>
 </prefer>
</alias>

The expanded configuration from Example 25.4, “Aliases and family names substitutions” would lead to the following PFL evolution:

Table 25.3: Results from generating PFL from fontconfig rules #

  

Order	Current PFL
Request	Alegreya SC
Rule 1	Alegreya SC, serif
Rule 2	Alegreya SC, Droid Serif, serif
Rule 3	Alegreya SC, Droid Serif, serif, STIXGeneral
Rule 4	Alegreya SC, Droid Serif, serif, Liberation Serif, STIXGeneral
Rule 5	Alegreya SC, Droid Serif, DejaVu Serif, serif, Liberation Serif, STIXGeneral

Note: Implications.

• In case multiple <accept> declarations for the same generic name exist, the declaration that is parsed last “wins”. If possible, do not use <accept> after user (/etc/fonts/conf.d/*-user.conf) when creating a system-wide configuration.

• In case multiple <prefer declarations for the same generic name exist, the declaration that is parsed last “wins”. If possible, do not use <prefer> before user in the system-wide configuration.

• Every <prefer> declaration overwrites <accept> declarations for the same generic name. If the administrator wants to allow the user to use <accept> and not only <prefer>, the administrator should not use <prefer> in the system-wide configuration. On the other hand, as users mostly use <prefer>, this should not have any detrimental effect. We also see the use of <prefer> in system-wide configurations.

Configuration of the GNOME desktop is managed with dconf. It is a hierarchically structured database or registry that allows users to modify their personal settings, and system administrators to set default or mandatory values for all users. dconf replaces the gconf system of GNOME 2.

Use dconf-editor to view the dconf options with a graphical user interface. Use dconf to access and modify configuration options with the command line.

The GNOME Tweaks tool provides an easy-to-use user interface for additional configuration options beyond the normal GNOME configuration. The tool can be started from the GNOME application menu or from the command line with gnome-tweak-tool.

Global dconf configuration parameters can be set in the /etc/dconf/db/ directory. This includes the configuration for GDM or locking certain configuration options for users.

Use the following procedure as an example to create a system-wide configuration:

You can use the graphical dconf-editor to create a profile with one user and then use dconf dump / to list all configuration options. The configuration options can then be stored in a global profile.

A detailed description of the global configuration is available at https://wiki.gnome.org/Projects/dconf/SystemAdministrators.

If you are running the GNOME desktop on Wayland and want to have your windows arranged next to each other, we recommend using the gTile GNOME extension. gTile lets you re-arrange windows based on a configurable grid scheme. For example, you can launch six terminals and have them arranged in 3 rows and 2 columns so that they use the whole desktop area.

25.3.3.1 Installing gTile #

  

Important

To use the gTile GNOME extension, you need to be running the GNOME desktop and have the chrome-gnome-shell (for SLED 15 SP4 and older) or gnome-browser-connector (for SLED 15 SP5 and newer) package installed.

1. Point your browser to the gTile extension web page https://extensions.gnome.org/extension/28/gtile/. If you see a warning about a missing browser extension, click the link and follow your Web browser's instruction on how to install and enable the GNOME Shell extension.

   

   Figure 25.1: Warning about a missing GNOME Shell extension #

     

2. After the GNOME Shell extension is installed in your Web browser, you can see an OFF button on the top right of the gTile Web page. To activate the gTile extension, switch it to ON by clicking it.

   

   Figure 25.2: GNOME gTile extension activated #

     

3. A gTile tray icon appears in the GNOME tray in the right side of the GNOME panel. You can use it to activate gTile window layouts.

   

   Figure 25.3: gTile tray icon #

     

For more information, see https://help.gnome.org/admin/.

You must have a configured and working NVIDIA Optimus GPU using the NVIDIA drivers included in SUSE Linux Enterprise 15 SP6 (see Section 25.4.3, “Installing NVIDIA drivers”), and an onboard Intel GPU. Bumblebee, the older switching tool for NVIDIA Optimus, must not be installed.

There must not be a /etc/X11/xorg.conf file, and no configuration files with active ServerLayout, Device, or Screen sections in the /etc/X11/xorg.conf.d directory.

SUSE Prime works only with X11. Use the loginctl command to see if your system is using X11 or Wayland:

> loginctl
   SESSION        UID USER             SEAT             TTY             
         2       1000 tux             seat0               
> loginctl show-session 2|grep Type
Type=x11

If your system uses Wayland, disable it by editing /etc/gdm/custom.conf and un-commenting WaylandEnable=false. Then reboot.

Your NVIDIA graphics card should already be installed and working. If it is not, see Section 25.4.3, “Installing NVIDIA drivers”.

Install the suse-prime package:

> sudo zypper install suse-prime

To switch your GPU run one of the following commands, then log out and log back in:

> sudo prime-select intel
> sudo prime-select intel2
> sudo prime-select nvidia

Use the intel driver when it is the modesetting driver. intel2 is for systems that use the xf86-video-intel driver. You can get this information by installing and running inxi:

> inxi -G
Graphics: Device-1: Intel Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics Controller
          Display Server: x11(X.org 1.20.1 ) drivers: modesetting (unloaded: fbdev, vesa)
          Resolution: 1920x1080@60.00hz
          OpenGL: renderer: Mesa DRI Intel Haswell Desktop version: 4.5 Mesa 18.2.8

Which GPU is currently active?

> sudo /usr/sbin/prime-select get-current
Driver configured: intel

If you need to identify your NVIDIA card so you know which driver to use, run the following command:

> /sbin/lspci | grep VGA

Follow these steps to install the drivers with Zypper.

List the available driver packages:

> sudo zypper se nvidia

Then install the drivers for your NVIDIA graphics card:

> sudo zypper se packagename