refactor: refactor the dbus directory

- Move the dbus directory to preferences/window_picker since it's only
  used for window picking within preferences.
- Simplify some of the code.
- Add documentation comments and explain the purpose of the dbus
  service.

src/extension.ts

@@ -12,9 +12,9 @@ import {WindowPreview} from 'resource:///org/gnome/shell/ui/windowPreview.js';
 import {WorkspaceAnimationController} from 'resource:///org/gnome/shell/ui/workspaceAnimation.js';
 
 // local modules
-import {Services} from './dbus/services.js';
 import {LinearFilterEffect} from './effect/linear_filter_effect.js';
 import {disableEffect, enableEffect} from './manager/event_manager.js';
+import {WindowPicker} from './preferences/window_picker/service.js';
 import {connections} from './utils/connections.js';
 import {constants, SHADOW_PADDING} from './utils/constants.js';
 import {_log, stackMsg} from './utils/log.js';
@@ -32,7 +32,7 @@ export default class RoundedWindowCornersReborn extends Extension {
     private _orig_prep_workspace_swt!: (workspaceIndices: number[]) => void;
     private _orig_finish_workspace_swt!: typeof WorkspaceAnimationController.prototype._finishWorkspaceSwitch;
 
-    private _services: Services | null = null;
+    private _windowPicker: WindowPicker | null = null;
 
     enable() {
         init_settings(this.getSettings());
@@ -45,9 +45,9 @@ export default class RoundedWindowCornersReborn extends Extension {
         this._orig_finish_workspace_swt =
             WorkspaceAnimationController.prototype._finishWorkspaceSwitch;
 
-        this._services = new Services();
+        this._windowPicker = new WindowPicker();
 
-        this._services.export();
+        this._windowPicker.export();
 
         // Enable rounded corners effects when gnome-shell is ready
         //
@@ -291,15 +291,15 @@ export default class RoundedWindowCornersReborn extends Extension {
         // Remove the item to open preferences page in background menu
         UI.RestoreBackgroundMenu();
 
-        this._services?.unexport();
+        this._windowPicker?.unexport();
         disableEffect();
 
         // Disconnect all signals in global connections.get()
         connections.get().disconnect_all();
         connections.del();
 
         // Set all props to null
-        this._services = null;
+        this._windowPicker = null;
 
         _log('Disabled');
 

src/preferences/widgets/app_row.ts

@@ -3,7 +3,7 @@ import GObject from 'gi://GObject';
 import Gtk from 'gi://Gtk';
 
 import {gettext as _} from 'resource:///org/gnome/Shell/Extensions/js/extensions/prefs.js';
-import {on_picked, pick} from '../../dbus/client.js';
+import {onPicked, pick} from '../window_picker/client.js';
 import {connections} from '../../utils/connections.js';
 
 export class AppRowClass extends Adw.ExpanderRow {
@@ -84,7 +84,7 @@ export class AppRowClass extends Adw.ExpanderRow {
     }
 
     on_pick(entry: Adw.EntryRow) {
-        on_picked(wm_instance_class => {
+        onPicked(wm_instance_class => {
             if (wm_instance_class === 'window-not-found') {
                 const win = this.root as unknown as Adw.PreferencesDialog;
                 win.add_toast(

src/preferences/window_picker/README.md

@@ -0,0 +1,21 @@
+# `window_picker`
+
+The extensions preferences window runs in a separate isolated process which has
+no access to GNOME Shell methods. However, the window picking functionality is
+based on GNOME Shell's Looking Glass.
+
+To allow the preferences window to communicate with the main process, the code
+in this directory creates a DBus service, which has a method to open the window
+picker and a signal to transmit the class of the selected window.
+
+## `iface.xml`
+
+Defines the DBus interface for the window picker.
+
+## `service.ts`
+
+Contains the implementation of the DBus interface.
+
+## `client.ts`
+
+Provides wrapper JavaScript functions around the DBus method calls.

src/preferences/window_picker/client.ts

@@ -0,0 +1,49 @@
+/**
+ * @file This file provides wrapper functions around the DBus window picker
+ * interface.
+ */
+
+import Gio from 'gi://Gio';
+
+const connection = Gio.DBus.session;
+const busName = 'org.gnome.Shell';
+const interfaceName = 'org.gnome.Shell.Extensions.RoundedWindowCorners';
+const objectPath = '/org/gnome/shell/extensions/RoundedWindowCorners';
+
+/** Open the window picker and select a window. */
+export function pick() {
+    connection.call(
+        busName,
+        objectPath,
+        interfaceName,
+        'pick',
+        null,
+        null,
+        Gio.DBusCallFlags.NO_AUTO_START,
+        -1,
+        null,
+        null,
+    );
+}
+
+/**
+ * Connect a callback to the `picked` signal, which is emitted when a window
+ * is picked.
+ *
+ * @param callback - The function to execute when the window is picked.
+ */
+export function onPicked(callback: (wmInstanceClass: string) => void) {
+    const id = connection.signal_subscribe(
+        busName,
+        interfaceName,
+        'picked',
+        objectPath,
+        null,
+        Gio.DBusSignalFlags.NONE,
+        (_conn, _sender, _objectPath, _iface, _signal, params) => {
+            const val = params.get_child_value(0);
+            callback(val.get_string()[0]);
+            connection.signal_unsubscribe(id);
+        },
+    );
+}

src/dbus/iface.xml → src/preferences/window_picker/iface.xml

@@ -1,10 +1,8 @@
 <node>
   <interface name="org.gnome.Shell.Extensions.RoundedWindowCorners">
-    <!-- This method is called in preferences to pick a window -->
     <method name="pick" />
-    <!-- If window is picked, send a signal to preferences -->
     <signal name="picked">
-      <arg name="window" type="s"/>
+      <arg name="window" type="s" />
     </signal>
   </interface>
 </node>

src/preferences/window_picker/service.ts

@@ -0,0 +1,91 @@
+/**
+ * @file This file contains the implementation of the DBus interface for the
+ * window picker. See the {@link WindowPicker} class for more information.
+ */
+
+import GLib from 'gi://GLib';
+import Gio from 'gi://Gio';
+import Meta from 'gi://Meta';
+
+import {Inspector} from 'resource:///org/gnome/shell/ui/lookingGlass.js';
+import * as Main from 'resource:///org/gnome/shell/ui/main.js';
+
+import {loadFile} from '../../utils/io.js';
+import {_log} from '../../utils/log.js';
+
+const iface = loadFile(import.meta.url, 'iface.xml');
+
+/**
+ * This class provides the implementation of the DBus interface for the window
+ * picker. It implements a single method - `pick` - which opens the window picker
+ * and allows the user to select a window.
+ */
+export class WindowPicker {
+    #dbus = Gio.DBusExportedObject.wrapJSObject(iface, this);
+
+    /** Emit the wm_class of the picked window to the `picked` signal. */
+    #sendPickedWindow(wmClass: string) {
+        this.#dbus.emit_signal('picked', new GLib.Variant('(s)', [wmClass]));
+    }
+
+    /**
+     * Open the window picker and select a window.
+     *
+     * This uses the window picker from GNOME's Looking Glass. This is the
+     * easiest way to pick a window, and this is also what's used by other
+     * extensions such as Blur my Shell.
+     */
+    pick() {
+        const lookingGlass = Main.createLookingGlass();
+        const inspector = new Inspector(lookingGlass);
+
+        inspector.connect('target', (me, target, x, y) => {
+            _log(`${me}: pick ${target} in ${x}, ${y}`);
+
+            // Remove the red border effect when the window is picked.
+            const effectName = 'lookingGlass_RedBorderEffect';
+            for (const effect of target.get_effects()) {
+                if (effect.toString().includes(effectName)) {
+                    target.remove_effect(effect);
+                }
+            }
+
+            let actor = target;
+
+            // If the picked actor is not a Meta.WindowActor, which happens
+            // often since it's usually a Meta.SurfaceActor, try to find its
+            // parent which is a Meta.WindowActor.
+            for (let i = 0; i < 2; i++) {
+                if (actor == null || actor instanceof Meta.WindowActor) {
+                    break;
+                }
+                actor = actor.get_parent();
+            }
+
+            if (!(actor instanceof Meta.WindowActor)) {
+                this.#sendPickedWindow('window-not-found');
+                return;
+            }
+
+            this.#sendPickedWindow(
+                actor.metaWindow.get_wm_class_instance() ?? 'window-not-found',
+            );
+        });
+
+        inspector.connect('closed', () => {
+            lookingGlass.close();
+        });
+    }
+
+    export() {
+        this.#dbus.export(
+            Gio.DBus.session,
+            '/org/gnome/shell/extensions/RoundedWindowCorners',
+        );
+        _log('DBus Service exported');
+    }
+
+    unexport() {
+        this.#dbus.unexport();
+    }
+}