app: move gtk theme management into separate class and module

Author: amezin

ddterm/app/application.js

@@ -42,6 +42,7 @@ const { Gdk, Gtk } = imports.gi;
 
 const { AppWindow } = imports.ddterm.app.appwindow;
 const { PrefsDialog } = imports.ddterm.pref.dialog;
+const { GtkThemeManager } = imports.ddterm.app.gtktheme;
 
 const APP_DIR = Me.dir.get_child('ddterm').get_child('app');
 
@@ -154,8 +155,16 @@ const Application = GObject.registerClass(
                 this.add_action(this.settings.create_action(key));
             });
 
-            this.settings.connect('changed::theme-variant', this.update_theme.bind(this));
-            this.update_theme();
+            this.theme_manager = new GtkThemeManager({
+                'gtk-settings': Gtk.Settings.get_default(),
+            });
+
+            this.settings.bind(
+                'theme-variant',
+                this.theme_manager,
+                'theme-variant',
+                Gio.SettingsBindFlags.GET
+            );
 
             const menus = Gtk.Builder.new_from_file(APP_DIR.get_child('menus.ui').get_path());
 
@@ -308,28 +317,6 @@ const Application = GObject.registerClass(
             return action;
         }
 
-        update_theme() {
-            const gtk_settings = Gtk.Settings.get_default();
-            const theme = this.settings.get_string('theme-variant');
-
-            switch (theme) {
-            case 'system':
-                gtk_settings.reset_property('gtk-application-prefer-dark-theme');
-                break;
-
-            case 'dark':
-                gtk_settings.gtk_application_prefer_dark_theme = true;
-                break;
-
-            case 'light':
-                gtk_settings.gtk_application_prefer_dark_theme = false;
-                break;
-
-            default:
-                printerr(`Unknown theme-variant: ${theme}`);
-            }
-        }
-
         bind_shortcut(action, settings_key) {
             const handler = this.update_shortcut.bind(this, action, settings_key);
 

ddterm/app/gtktheme.js

@@ -0,0 +1,65 @@
+/*
+    Copyright © 2023 Aleksandr Mezin
+
+    This file is part of ddterm GNOME Shell extension.
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+
+'use strict';
+
+const { GObject, Gtk } = imports.gi;
+
+var GtkThemeManager = GObject.registerClass(
+    {
+        Properties: {
+            'gtk-settings': GObject.ParamSpec.object(
+                'gtk-settings',
+                '',
+                '',
+                GObject.ParamFlags.READWRITE | GObject.ParamFlags.CONSTRUCT_ONLY,
+                Gtk.Settings
+            ),
+            'theme-variant': GObject.ParamSpec.string(
+                'theme-variant',
+                '',
+                '',
+                GObject.ParamFlags.WRITABLE,
+                null
+            ),
+        },
+    },
+    class DDTermGtkThemeManager extends GObject.Object {
+        set theme_variant(value) {
+            switch (value) {
+            case 'system':
+                this.gtk_settings.reset_property('gtk-application-prefer-dark-theme');
+                break;
+
+            case 'dark':
+                this.gtk_settings.gtk_application_prefer_dark_theme = true;
+                break;
+
+            case 'light':
+                this.gtk_settings.gtk_application_prefer_dark_theme = false;
+                break;
+
+            default:
+                printerr(`Unknown theme-variant: ${value}`);
+            }
+        }
+    }
+);
+
+/* exported GtkThemeManager */