GtkFontDialogButton and Gsettings

The preference dialog

If the user clicks on the preference menu, a preference dialog appears.

It has only one button, which is a GtkFontDialogButton widget. You can add more widgets on the dialog but this simple dialog isn’t so bad for the first example program.

If the button is clicked, a FontDialog appears like this.

If the user chooses a font and clicks on the select button, the font is changed.

GtkFontDialogButton and GtkFontDialog are available since GTK version 4.10. They replace GtkFontButton and GtkFontChooserDialog, which are deprecated since 4.10.

A composite widget

The preference dialog has GtkBox, GtkLabel and GtkFontButton in it and is defined as a composite widget. The following is the template ui file for TfePref.

<?xml version="1.0" encoding="UTF-8"?>
<interface>
  <template class="TfePref" parent="GtkWindow">
    <property name="title">Preferences</property>
    <property name="resizable">FALSE</property>
    <property name="modal">TRUE</property>
    <child>
      <object class="GtkBox">
        <property name="orientation">GTK_ORIENTATION_HORIZONTAL</property>
        <property name="spacing">12</property>
        <property name="halign">GTK_ALIGN_CENTER</property>
        <property name="margin-start">12</property>
        <property name="margin-end">12</property>
        <property name="margin-top">12</property>
        <property name="margin-bottom">12</property>
        <child>
          <object class="GtkLabel">
            <property name="label">Font:</property>
            <property name="xalign">1</property>
          </object>
        </child>
        <child>
          <object class="GtkFontDialogButton" id="font_dialog_btn">
            <property name="dialog">
              <object class="GtkFontDialog"/>
            </property>
          </object>
        </child>
      </object>
    </child>
  </template>
</interface>

• Template tag specifies a composite widget. The class attribute specifies the class name, which is “TfePref”. The parent attribute is GtkWindow. Therefore. TfePref is a child class of GtkWindow. A parent attribute is optional but it is recommended to write it explicitly. You can make TfePref as a child of GtkDialog, but GtkDialog is deprecated since version 4.10.
• There are three properties, title, resizable and modal.
• TfePref has a child widget GtkBox which is horizontal. The box has two children GtkLabel and GtkFontDialogButton.

The header file

The file tfepref.h defines types and declares a public function.

#pragma once

#include <gtk/gtk.h>

#define TFE_TYPE_PREF tfe_pref_get_type ()
G_DECLARE_FINAL_TYPE (TfePref, tfe_pref, TFE, PREF, GtkWindow)

GtkWidget *
tfe_pref_new (void);

• 5: Defines the type TFE_TYPE_PREF, which is a macro replaced by tfe_pref_get_type ().
• 6: The macro G_DECLAER_FINAL_TYPE expands to:
  • The function tfe_pref_get_type () is declared.
  • TfePrep type is defined as a typedef of struct _TfePrep.
  • TfePrepClass type is defined as a typedef of struct {GtkWindowClass *parent;}.
  • Two functions TFE_PREF () and TFE_IS_PREF () is defined.
• 8-9:The function tfe_pref_new is declared. It creates a new TfePref instance.

The C file for composite widget

The following codes are extracted from the file tfepref.c.

#include <gtk/gtk.h>
#include "tfepref.h"

struct _TfePref
{
  GtkWindow parent;
  GtkFontDialogButton *font_dialog_btn;
};

G_DEFINE_FINAL_TYPE (TfePref, tfe_pref, GTK_TYPE_WINDOW);

static void
tfe_pref_dispose (GObject *gobject) {
  TfePref *pref = TFE_PREF (gobject);
  gtk_widget_dispose_template (GTK_WIDGET (pref), TFE_TYPE_PREF);
  G_OBJECT_CLASS (tfe_pref_parent_class)->dispose (gobject);
}

static void
tfe_pref_init (TfePref *pref) {
  gtk_widget_init_template (GTK_WIDGET (pref));
}

static void
tfe_pref_class_init (TfePrefClass *class) {
  G_OBJECT_CLASS (class)->dispose = tfe_pref_dispose;
  gtk_widget_class_set_template_from_resource (GTK_WIDGET_CLASS (class), "/com/github/ToshioCP/tfe/tfepref.ui");
  gtk_widget_class_bind_template_child (GTK_WIDGET_CLASS (class), TfePref, font_dialog_btn);
}

GtkWidget *
tfe_pref_new (void) {
  return GTK_WIDGET (g_object_new (TFE_TYPE_PREF, NULL));
}

• The structure _TfePref has font_dialog_btn member. It points the GtkFontDialogButton object specified in the XML file “tfepref.ui”. The member name font_dialog_btn must be the same as the GtkFontDialogButton id attribute in the XML file.
• G_DEFINE_FINAL_TYPE macro expands to:
  • The declaration of the functions tfe_pref_init and tfe_pref_class_init. They are defined in the following part of the program.
  • The definition of the variable tfe_pref_parent_class.
  • The definition of the function tfe_pref_get_type.
• The function tfe_pref_class_init initializes the TfePref class. The function gtk_widget_class_set_template_from_resource initializes the composite widget template from the XML resource. The function gtk_widget_class_bind_template_child connects the TfePref structure member font_dialog_btn and the GtkFontDialogButton in the XML. The member name and the id attribute value must be the same.
• The function tfe_pref_init initializes a newly created instance. The function gtk_widget_init_template creates and initializes child widgets.
• The function tfe_pref_dispose releases objects. The function gtk_widget_dispose_template releases child widgets.

GtkFontDialogButton and Pango

If the GtkFontDialogButton button is clicked, the GtkFontDialog dialog appears. A user can choose a font on the dialog. If the user clicks on the “select” button, the dialog disappears. And the font information is given to the GtkFontDialogButton instance. The font data is taken with the method gtk_font_dialog_button_get_font_desc. It returns a pointer to the PangoFontDescription structure.

Pango is a text layout engine. The documentation is on the internet.

PangoFontDescription is a C structure and it isn’t allowed to access directly. The document is here. If you want to retrieve the font information, there are several functions.

• pango_font_description_to_string returns a string like “Jamrul Bold Italic Semi-Expanded 12”.
• pango_font_description_get_family returns a font family like “Jamrul”.
• pango_font_description_get_weight returns a PangoWeight constant like PANGO_WEIGHT_BOLD.
• pango_font_description_get_style returns a PangoStyle constant like PANGO_STYLE_ITALIC.
• pango_font_description_get_stretch returns a PangoStretch constant like PANGO_STRETCH_SEMI_EXPANDED.
• pango_font_description_get_size returns an integer like 12. Its unit is point or pixel (device unit). The function pango_font_description_get_size_is_absolute returns TRUE if the unit is absolute that means device unit. Otherwise the unit is point.

GSettings

We want to maintain the font data after the application quits. There are some ways to implement.

• Make a configuration file. For example, a text file “~/.config/tfe/font_desc.cfg” keeps font information.
• Use GSettings object. The basic idea of GSettings are similar to configuration file. Configuration information data is put into a database file.

GSettings is simple and easy to use but a bit hard to understand the concept. This subsection describes the concept first and then how to program it.

GSettings schema

GSettings schema describes a set of keys, value types and some other information. GSettings object uses this schema and it writes/reads the value of a key to/from the right place in the database.

• A schema has an id. The id must be unique. We often use the same string as application id, but schema id and application id are different. You can use different name from application id. Schema id is a string delimited by periods. For example, “com.github.ToshioCP.tfe” is a correct schema id.
• A schema usually has a path. The path is a location in the database. Each key is stored under the path. For example, if a key font-desc is defined with a path /com/github/ToshioCP/tfe/, the key’s location in the database is /com/github/ToshioCP/tfe/font-desc. Path is a string begins with and ends with a slash (/). And it is delimited by slashes.
• GSettings save information as key-value style. Key is a string begins with a lower case character followed by lower case, digit or dash (-) and ends with lower case or digit. No consecutive dashes are allowed. Values can be any type. GSettings stores values as GVariant type, which can be, for example, integer, double, boolean, string or complex types like an array. The type of values needs to be defined in the schema.
• A default value needs to be set for each key.
• A summery and description can be set for each key optionally.

Schemas are described in an XML format. For example,

<?xml version="1.0" encoding="UTF-8"?>
<schemalist>
  <schema path="/com/github/ToshioCP/tfe/" id="com.github.ToshioCP.tfe">
    <key name="font-desc" type="s">
      <default>'Monospace 12'</default>
      <summary>Font</summary>
      <description>A font to be used for textview.</description>
    </key>
  </schema>
</schemalist>

• 4: The type attribute is “s”. It is GVariant type string. For GVariant type string, see GLib API Reference – GVariant Type Strings. Other common types are:
  • “b”: gboolean
  • “i”: gint32.
  • “d”: double.

Further information is in:

• GLib API Reference – GVariant Format Strings
• GLib API Reference – GVariant Text Format
• GLib API Reference – GVariant
• GLib API Reference – VariantType

Gsettings command

First, let’s try gsettings application. It is a configuration tool for GSettings.

$ gsettings help
Usage:
  gsettings --version
  gsettings [--schemadir SCHEMADIR] COMMAND [ARGS?]

Commands:
  help                      Show this information
  list-schemas              List installed schemas
  list-relocatable-schemas  List relocatable schemas
  list-keys                 List keys in a schema
  list-children             List children of a schema
  list-recursively          List keys and values, recursively
  range                     Queries the range of a key
  describe                  Queries the description of a key
  get                       Get the value of a key
  set                       Set the value of a key
  reset                     Reset the value of a key
  reset-recursively         Reset all values in a given schema
  writable                  Check if a key is writable
  monitor                   Watch for changes

Use "gsettings help COMMAND" to get detailed help.

List schemas.

$ gsettings list-schemas
org.gnome.rhythmbox.podcast
ca.desrt.dconf-editor.Demo.Empty
org.gnome.gedit.preferences.ui
org.gnome.evolution-data-server.calendar
org.gnome.rhythmbox.plugins.generic-player

... ...

Each line is an id of a schema. Each schema has a key-value configuration data. You can see them with list-recursively command. Let’s look at the keys and values of org.gnome.calculator schema.

$ gsettings list-recursively org.gnome.calculator
org.gnome.calculator accuracy 9
org.gnome.calculator angle-units 'degrees'
org.gnome.calculator base 10
org.gnome.calculator button-mode 'basic'
org.gnome.calculator number-format 'automatic'
org.gnome.calculator precision 2000
org.gnome.calculator refresh-interval 604800
org.gnome.calculator show-thousands false
org.gnome.calculator show-zeroes false
org.gnome.calculator source-currency ''
org.gnome.calculator source-units 'degree'
org.gnome.calculator target-currency ''
org.gnome.calculator target-units 'radian'
org.gnome.calculator window-position (-1, -1)
org.gnome.calculator word-size 64

This schema is used by GNOME Calculator. Run the calculator and change the mode, then check the schema again.

$ gnome-calculator

Change the mode to advanced and quit.

Run gsettings and check the value of button-mode.

$ gsettings list-recursively org.gnome.calculator

... ...

org.gnome.calculator button-mode 'advanced'

... ...

Now we know that GNOME Calculator used gsettings and it has set button-mode key to “advanced”. The value remains even the calculator quits. So when the calculator runs again, it will appear as an advanced mode.

Glib-compile-schemas utility

GSettings schemas are specified with an XML format. The XML schema files must have the filename extension .gschema.xml. The following is the XML schema file for the application tfe.

<?xml version="1.0" encoding="UTF-8"?>
<schemalist>
  <schema path="/com/github/ToshioCP/tfe/" id="com.github.ToshioCP.tfe">
    <key name="font-desc" type="s">
      <default>'Monospace 12'</default>
      <summary>Font</summary>
      <description>A font to be used for textview.</description>
    </key>
  </schema>
</schemalist>

The filename is “com.github.ToshioCP.tfe.gschema.xml”. Schema XML filenames are usually the schema id followed by “.gschema.xml” suffix. You can use different name from schema id, but it is not recommended.

• 2: The top level element is <schemalist>.
• 3: schema tag has path and id attributes. A path determines where the settings are stored in the conceptual global tree of settings. An id identifies the schema.
• 4: Key tag has two attributes. Name is the name of the key. Type is the type of the value of the key and it is a GVariant Format String.
• 5: default value of the key font-desc is Monospace 12.
• 6: Summery and description elements describes the key. They are optional, but it is recommended to add them in the XML file.

The XML file is compiled by glib-compile-schemas. When compiling, glib-compile-schemas compiles all the XML files which have “.gschema.xml” file extension in the directory given as an argument. It converts the XML file into a binary file gschemas.compiled. Suppose the XML file above is under tfe6 directory.

$ glib-compile-schemas tfe6

Then, gschemas.compiled is generated under tfe6. When you test your application, set GSETTINGS_SCHEMA_DIR environment variable so that GSettings objet can find gschemas.compiled.

$ GSETTINGS_SCHEMA_DIR=(the directory gschemas.compiled is located):$GSETTINGS_SCHEMA_DIR (your application name)

GSettings object looks for this file by the following process.

• It searches glib-2.0/schemas subdirectories of all the directories specified in the environment variable XDG_DATA_DIRS. Common directores are /usr/share/glib-2.0/schemas and /usr/local/share/glib-2.0/schemas.
• If $HOME/.local/share/glib-2.0/schemas exists, it is also searched.
• If GSETTINGS_SCHEMA_DIR environment variable is defined, it searches all the directories specified in the variable. GSETTINGS_SCHEMA_DIR can specify multiple directories delimited by colon (:).

The directories above includes more than one .gschema.xml file. Therefore, when you install your application, follow the instruction below to install your schemas.

1. Make .gschema.xml file.
2. Copy it to one of the directories above. For example, $HOME/.local/share/glib-2.0/schemas.
3. Run glib-compile-schemas on the directory. It compiles all the schema files in the directory and creates or updates the database file gschemas.compiled.

GSettings object and binding

Now, we go on to the next topic, how to program GSettings.

You need to compile your schema file in advance.

Suppose id, key, class name and a property name are:

• GSettings id: com.github.ToshioCP.sample
• GSettings key: sample_key
• The class name: Sample
• The property to bind: sample_property

The example below uses g_settings_bind. If you use it, GSettings key and instance property must have the same the type. In the example, it is assumed that the type of “sample_key” and “sample_property” are the same.

GSettings *settings;
Sample *sample_object;

settings = g_settings_new ("com.github.ToshioCP.sample");
sample_object = sample_new ();
g_settings_bind (settings, "sample_key", sample_object, "sample_property", G_SETTINGS_BIND_DEFAULT);

The function g_settings_bind binds the GSettings value and the property of the instance. If the property value is changed, the GSettings value is also changed, and vice versa. The two values are always the same.

The function g_settings_bind is simple and easy but it isn’t always possible. The type of GSettings are restricted to the type GVariant has. Some property types are out of GVariant. For example, GtkFontDialogButton has “font-desc” property and its type is PangoFontDescription. PangoFontDescription is a C structure and it is wrapped in a boxed type GValue to store in the property. GVariant doesn’t support boxed type.

In that case, another function g_settings_bind_with_mapping is used. It binds GSettings GVariant value and object property via GValue with mapping functions.

void
g_settings_bind_with_mapping (
  GSettings* settings,
  const gchar* key,
  GObject* object,
  const gchar* property,
  GSettingsBindFlags flags, // G_SETTINGS_BIND_DEFAULT is commonly used
  GSettingsBindGetMapping get_mapping, // GSettings => property, See the example below
  GSettingsBindSetMapping set_mapping, // property => GSettings, See the example below
  gpointer user_data, // NULL if unnecessary
  GDestroyNotify destroy //NULL if unnecessary
)

The mapping functions are defined like these:

gboolean
(* GSettingsBindGetMapping) (
  GValue* value,
  GVariant* variant,
  gpointer user_data
)

GVariant*
(* GSettingsBindSetMapping) (
  const GValue* value,
  const GVariantType* expected_type,
  gpointer user_data
)

The following codes are extracted from tfepref.c.

static gboolean // GSettings => property
get_mapping (GValue* value, GVariant* variant, gpointer user_data) {
  const char *s = g_variant_get_string (variant, NULL);
  PangoFontDescription *font_desc = pango_font_description_from_string (s);
  g_value_take_boxed (value, font_desc);
  return TRUE;
}

static GVariant* // Property => GSettings
set_mapping (const GValue* value, const GVariantType* expected_type, gpointer user_data) {
  char*font_desc_string = pango_font_description_to_string (g_value_get_boxed (value));
  return g_variant_new_take_string (font_desc_string);
}

static void
tfe_pref_init (TfePref *pref) {
  gtk_widget_init_template (GTK_WIDGET (pref));
  pref->settings = g_settings_new ("com.github.ToshioCP.tfe");
  g_settings_bind_with_mapping (pref->settings, "font-desc", pref->font_dialog_btn, "font-desc", G_SETTINGS_BIND_DEFAULT,
      get_mapping, set_mapping, NULL, NULL);
}

• 15-21: This function tfe_pref_init initializes the new TfePref instance.
• 18: Creates a new GSettings instance. The id is “com.github.ToshioCP.tfe”.
• 19-20: Binds the GSettings “font-desc” and the GtkFontDialogButton property “font-desc”. The mapping functions are get_mapping and set_mapping.
• 1-7: The mapping function from GSettings to the property. The first argument value is a GValue to be stored in the property. The second argument variant is a GVarinat structure that comes from the GSettings value.
• 3: Retrieves a string from the GVariant structure.
• 4: Build a PangoFontDescription structure from the string and assigns its address to font_desc.
• 5: Puts font_desc into the GValue value. The ownership of font_desc moves to value.
• 6: Returns TRUE that means the mapping succeeds.
• 9-13: The mapping function from the property to GSettings. The first argument value holds the property data. The second argument expected_type is the type of GVariant that the GSettings value has. It isn’t used in this function.
• 11: Gets the PangoFontDescription structure from value and converts it to string.
• 12: The string is inserted to a GVariant structure. The ownership of the string font_desc_string moves to the returned value.

C file

The following is the full codes of tfepref.c

#include <gtk/gtk.h>
#include "tfepref.h"

struct _TfePref
{
  GtkWindow parent;
  GSettings *settings;
  GtkFontDialogButton *font_dialog_btn;
};

G_DEFINE_FINAL_TYPE (TfePref, tfe_pref, GTK_TYPE_WINDOW);

static void
tfe_pref_dispose (GObject *gobject) {
  TfePref *pref = TFE_PREF (gobject);

  /* GSetting bindings are automatically removed when the object is finalized, so it isn't necessary to unbind them explicitly.*/
  g_clear_object (&pref->settings);
  gtk_widget_dispose_template (GTK_WIDGET (pref), TFE_TYPE_PREF);
  G_OBJECT_CLASS (tfe_pref_parent_class)->dispose (gobject);
}

/* ---------- get_mapping/set_mapping ---------- */
static gboolean // GSettings => property
get_mapping (GValue* value, GVariant* variant, gpointer user_data) {
  const char *s = g_variant_get_string (variant, NULL);
  PangoFontDescription *font_desc = pango_font_description_from_string (s);
  g_value_take_boxed (value, font_desc);
  return TRUE;
}

static GVariant* // Property => GSettings
set_mapping (const GValue* value, const GVariantType* expected_type, gpointer user_data) {
  char*font_desc_string = pango_font_description_to_string (g_value_get_boxed (value));
  return g_variant_new_take_string (font_desc_string);
}

static void
tfe_pref_init (TfePref *pref) {
  gtk_widget_init_template (GTK_WIDGET (pref));
  pref->settings = g_settings_new ("com.github.ToshioCP.tfe");
  g_settings_bind_with_mapping (pref->settings, "font-desc", pref->font_dialog_btn, "font-desc", G_SETTINGS_BIND_DEFAULT,
      get_mapping, set_mapping, NULL, NULL);
}

static void
tfe_pref_class_init (TfePrefClass *class) {
  G_OBJECT_CLASS (class)->dispose = tfe_pref_dispose;
  gtk_widget_class_set_template_from_resource (GTK_WIDGET_CLASS (class), "/com/github/ToshioCP/tfe/tfepref.ui");
  gtk_widget_class_bind_template_child (GTK_WIDGET_CLASS (class), TfePref, font_dialog_btn);
}

GtkWidget *
tfe_pref_new (void) {
  return GTK_WIDGET (g_object_new (TFE_TYPE_PREF, NULL));
}

Test program

There’s a test program located at src/tfe6/test directory.

#include <gtk/gtk.h>
#include "../tfepref.h"

GSettings *settings;

// "changed::font-desc" signal handler
static void
changed_font_desc_cb (GSettings *settings, char *key, gpointer user_data) {
  char *s;
  s = g_settings_get_string (settings, key);
  g_print ("%s\n", s);
  g_free (s);
}

static void
app_shutdown (GApplication *application) {
  g_object_unref (settings);
}

static void
app_activate (GApplication *application) {
  GtkWidget *pref = tfe_pref_new ();

  gtk_window_set_application (GTK_WINDOW (pref), GTK_APPLICATION (application));
  gtk_window_present (GTK_WINDOW (pref));
}

static void
app_startup (GApplication *application) {
  settings = g_settings_new ("com.github.ToshioCP.tfe");
  g_signal_connect (settings, "changed::font-desc", G_CALLBACK (changed_font_desc_cb), NULL);
  g_print ("%s\n", "Change the font with the font button. Then the new font will be printed out.\n");
}

#define APPLICATION_ID "com.github.ToshioCP.test_tfe_pref"

int
main (int argc, char **argv) {
  GtkApplication *app;
  int stat;

  app = gtk_application_new (APPLICATION_ID, G_APPLICATION_DEFAULT_FLAGS);
  g_signal_connect (app, "startup", G_CALLBACK (app_startup), NULL);
  g_signal_connect (app, "activate", G_CALLBACK (app_activate), NULL);
  g_signal_connect (app, "shutdown", G_CALLBACK (app_shutdown), NULL);
  stat =g_application_run (G_APPLICATION (app), argc, argv);
  g_object_unref (app);
  return stat;
}

This program sets its active window to TfePref instance, which is a child object of GtkWindow.

It sets the “changed::font-desc” signal handler in the startup function. The process from the user’s font selection to the handler is:

• The user clicked on the GtkFontDialogButton and GtkFontDialog appears.
• He/she selects a new font.
• The “font-desc” property of the GtkFontDialogButton instance is changed.
• The value of “font-desc” key on the GSettings database is changed since it is bound to the property.
• The “changed::font-desc” signal on the GSettings instance is emitted.
• The handler is called.

The program building is divided into four steps.

• Compile the schema file
• Compile the XML file to a resource (C source file)
• Compile the C files
• Run the executable file

Commands are shown in the next four sub-subsections. You don’t need to try them. The final sub-subsection shows the meson-ninja way, which is the easiest.

Compile the schema file

$ cd src/tef6/test
$ cp ../com.github.ToshioCP.tfe.gschema.xml com.github.ToshioCP.tfe.gschema.xml
$ glib-compile-schemas .

Be careful. The commands glib-compile-schemas has an argument “.”, which means the current directory. This results in creating gschemas.compiled file.

Compile the XML file

$ glib-compile-resources --sourcedir=.. --generate-source --target=resource.c ../tfe.gresource.xml

Compile the C file

$ gcc `pkg-config --cflags gtk4` test_pref.c ../tfepref.c resource.c `pkg-config --libs gtk4`

Run the executable file

$ GSETTINGS_SCHEMA_DIR=. ./a.out

Jamrul Italic Semi-Expanded 12 # <= select Jamrul Italic 12
Monospace 12 #<= select Monospace Regular 12

Meson-ninja way

Meson wraps up the commands above. Create the following text and save it to meson.build.

Note: Gtk4-tutorial repository has meson.build file that defines several tests. So you can try it instead of the following text.

project('tfe_pref_test', 'c')

gtkdep = dependency('gtk4')

gnome=import('gnome')
resources = gnome.compile_resources('resources','../tfe.gresource.xml', source_dir: '..')
gnome.compile_schemas(build_by_default: true, depend_files: 'com.github.ToshioCP.tfe.gschema.xml')

executable('test_pref', ['test_pref.c', '../tfepref.c'], resources, dependencies: gtkdep, export_dynamic: true, install: false)

• Project name is ‘tfe_pref_test’ and it is written in C language.
• It depends on GTK4 library.
• It uses GNOME module. Modules are prepared by Meson.
• GNOME module has compile_resources method. When you call this method, you need the prefix “gnome.”.
  • The target filename is resources.
  • The definition XML file is ‘../tfe.gresource.xml’.
  • The source dir is ‘..’. All the ui files are located there.
• GNOME module has compile_schemas method. It compiles the schema file ‘com.github.ToshioCP.tfe.gschema.xml’. You need to copy ‘../com.github.ToshioCP.tfe.gschema.xml’ to the current directory in advance.
• It creates an executable file ‘test_pref’. The source files are ‘test_pref.c’, ‘../tfepref.c’ and resources, which is made by gnome.compile_resources. It depends on gtkdep, which is GTK4 library. The symbols are exported and no installation support.

Type like this to build and test the program.

$ cd src/tef6/test
$ cp ../com.github.ToshioCP.tfe.gschema.xml com.github.ToshioCP.tfe.gschema.xml
$ meson setup _build
$ ninja -C _build
$ GSETTINGS_SCHEMA_DIR=_build _build/test_pref

A window appears and you can choose a font via GtkFontDialog. If you select a new font, the font string is output through the standard output.