Port wallpaper plugin to new dbus plugin

Add dconf/gsettings as fallback method

yin_yang/plugins/gtk.py

@@ -79,48 +79,52 @@ def available(self) -> bool:
 
 
 class _Kde(DBusPlugin):
-    name = 'GTK'
+    @property
+    def name(self):
+        return 'GTK'
 
     def __init__(self):
         super().__init__()
         self.theme_light = 'Breeze'
         self.theme_dark = 'Breeze'
+        self.message_data = ['org.kde.GtkConfig', '/GtkConfig', 'org.kde.GtkConfig', 'setGtkTheme']
 
-    def create_message(self, theme: str) -> QDBusMessage:
-        message = QDBusMessage.createMethodCall(
-            'org.kde.GtkConfig',
-            '/GtkConfig',
-            'org.kde.GtkConfig',
-            'setGtkTheme'
-        )
-        message.setArguments([theme])
-        return message
+    def create_message(self, theme: str):
+        self.message = QDBusMessage.createMethodCall(*self.message_data)
+        self.message.setArguments([theme])
 
     def set_theme(self, theme: str):
-        response = self.call(self.create_message(theme))
+        """Call DBus interface of kde-ftk-config if installed.
+        Otherwise try changing xsettingsd's conf and dconf"""
 
-        if response.type() != QDBusMessage.MessageType.ErrorMessage:
+        if self.connection.interface().isServiceRegistered('org.kde.GtkConfig'):
+            super().set_theme(theme)
             return
 
-        logger.warning('kde-gtk-config not available, trying xsettingsd')
+        # User don't have kde-gtk-config installed, try xsettingsd and dconf
+        logger.warning('kde-gtk-config not available, trying xsettingsd and dconf')
+
+        # xsettingsd
         xsettingsd_conf_path = Path.home() / '.config/xsettingsd/xsettingsd.conf'
         if not xsettingsd_conf_path.exists():
             logger.warning('xsettingsd not available')
             return
-
         with open(xsettingsd_conf_path, 'r') as f:
             lines = f.readlines()
             for i, line in enumerate(lines):
                 if line.startswith('Net/ThemeName'):
                     lines[i] = f'Net/ThemeName "{theme}"\n'
                     break
-
         with open(xsettingsd_conf_path, 'w') as f:
             f.writelines(lines)
-
         # send signal to read new config
         subprocess.run(['killall', '-HUP', 'xsettingsd'])
 
+        # change dconf db. since dconf sending data as GVariant, use gsettings instead
+        subprocess.run(['gsettings', 'set', 'org.gnome.desktop.interface', 'gtk-theme', '{theme}'])
+        color_scheme = 'prefer-dark' if theme == self.theme_dark else 'prefer-light'
+        subprocess.run(['gsettings', 'set', 'org.gnome.desktop.interface', 'color-scheme', f'{color_scheme}'])
+
 
 class _Xfce(PluginCommandline):
     def __init__(self):