Remodel GestureController lifetimes (#2355)

Co-authored-by: Leo <[email protected]>

Author: leolost2605

src/Gestures/GestureController.vala

@@ -35,12 +35,12 @@ public class Gala.GestureController : Object {
     public GestureAction action { get; construct; }
     public WindowManager wm { get; construct; }
 
-    private GestureTarget? _target;
-    public GestureTarget target {
+    private unowned RootTarget? _target;
+    public RootTarget target {
         get { return _target; }
-        set {
+        private set {
             _target = value;
-            target.propagate (UPDATE, action, progress);
+            _target.propagate (UPDATE, action, progress);
         }
     }
 
@@ -90,8 +90,21 @@ public class Gala.GestureController : Object {
 
     private SpringTimeline? timeline;
 
-    public GestureController (GestureAction action, GestureTarget target, WindowManager wm) {
-        Object (action: action, target: target, wm: wm);
+    public GestureController (GestureAction action, WindowManager wm) {
+        Object (action: action, wm: wm);
+    }
+
+    /**
+     * Do not call this directly, use {@link RooTarget.add_controller} instead.
+     */
+    public void attached (RootTarget target) {
+        ref ();
+        this.target = target;
+    }
+
+    public void detached () {
+        _target = null;
+        unref ();
     }
 
     public void enable_touchpad () {

src/Gestures/RootTarget.vala

@@ -0,0 +1,13 @@
+/*
+ * Copyright 2025 elementary, Inc. (https://elementary.io)
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ *
+ * Authored by: Leonhard Kargl <[email protected]>
+ */
+
+public interface Gala.RootTarget : Object, GestureTarget {
+    public void add_gesture_controller (GestureController controller) requires (controller.target == null) {
+        controller.attached (this);
+        weak_ref (controller.detached);
+    }
+}

src/Gestures/ScrollBackend.vala

@@ -26,7 +26,6 @@ public class Gala.ScrollBackend : Object, GestureBackend {
     private const double FINISH_DELTA_HORIZONTAL = 40;
     private const double FINISH_DELTA_VERTICAL = 30;
 
-    public Clutter.Actor actor { get; construct; }
     public Clutter.Orientation orientation { get; construct; }
     public GestureSettings settings { get; construct; }
 
@@ -46,7 +45,7 @@ public class Gala.ScrollBackend : Object, GestureBackend {
     }
 
     public ScrollBackend (Clutter.Actor actor, Clutter.Orientation orientation, GestureSettings settings) {
-        Object (actor: actor, orientation: orientation, settings: settings);
+        Object (orientation: orientation, settings: settings);
 
         actor.captured_event.connect (on_scroll_event);
         actor.leave_event.connect (on_leave_event);

src/ShellClients/PanelWindow.vala

@@ -5,7 +5,7 @@
  * Authored by: Leonhard Kargl <[email protected]>
  */
 
-public class Gala.PanelWindow : ShellWindow {
+public class Gala.PanelWindow : ShellWindow, RootTarget {
     private const int ANIMATION_DURATION = 250;
 
     private static HashTable<Meta.Window, Meta.Strut?> window_struts = new HashTable<Meta.Window, Meta.Strut?> (null, null);
@@ -50,8 +50,6 @@ public class Gala.PanelWindow : ShellWindow {
             if (window_struts.remove (window)) {
                 update_struts ();
             }
-
-            gesture_controller = null; // make it release its reference on us
         });
 
         notify["anchor"].connect (() => position = Position.from_anchor (anchor));
@@ -63,7 +61,8 @@ public class Gala.PanelWindow : ShellWindow {
         window.size_changed.connect (update_strut);
         window.position_changed.connect (update_strut);
 
-        gesture_controller = new GestureController (DOCK, this, wm);
+        gesture_controller = new GestureController (DOCK, wm);
+        add_gesture_controller (gesture_controller);
 
         window.display.in_fullscreen_changed.connect (() => {
             if (wm.get_display ().get_monitor_in_fullscreen (window.get_monitor ())) {

src/Widgets/MultitaskingView/MultitaskingView.vala

@@ -20,7 +20,7 @@
  * preparing the wm, opening the components and holds containers for
  * the icon groups, the WorkspaceClones and the MonitorClones.
  */
-public class Gala.MultitaskingView : ActorTarget, ActivatableComponent {
+public class Gala.MultitaskingView : ActorTarget, RootTarget, ActivatableComponent {
     public const int ANIMATION_DURATION = 250;
 
     private GestureController workspaces_gesture_controller;
@@ -57,18 +57,20 @@ public class Gala.MultitaskingView : ActorTarget, ActivatableComponent {
         opened = false;
         display = wm.get_display ();
 
-        multitasking_gesture_controller = new GestureController (MULTITASKING_VIEW, this, wm);
+        multitasking_gesture_controller = new GestureController (MULTITASKING_VIEW, wm);
         multitasking_gesture_controller.enable_touchpad ();
+        add_gesture_controller (multitasking_gesture_controller);
 
         add_target (ShellClientsManager.get_instance ()); // For hiding the panels
 
         workspaces = new WorkspaceRow (display);
 
-        workspaces_gesture_controller = new GestureController (SWITCH_WORKSPACE, this, wm) {
+        workspaces_gesture_controller = new GestureController (SWITCH_WORKSPACE, wm) {
             overshoot_upper_clamp = 0.1
         };
         workspaces_gesture_controller.enable_touchpad ();
         workspaces_gesture_controller.enable_scroll (this, HORIZONTAL);
+        add_gesture_controller (workspaces_gesture_controller);
 
         icon_groups = new IconGroupContainer (display.get_monitor_scale (display.get_primary_monitor ()));
 

src/Widgets/MultitaskingView/WindowClone.vala

@@ -8,7 +8,7 @@
  * A container for a clone of the texture of a MetaWindow, a WindowIcon, a Tooltip with the title,
  * a close button and a shadow. Used together with the WindowCloneContainer.
  */
-public class Gala.WindowClone : ActorTarget {
+public class Gala.WindowClone : ActorTarget, RootTarget {
     private const int WINDOW_ICON_SIZE = 64;
     private const int ACTIVE_SHAPE_SIZE = 12;
     private const int FADE_ANIMATION_DURATION = 200;
@@ -93,8 +93,9 @@ public class Gala.WindowClone : ActorTarget {
     construct {
         reactive = true;
 
-        gesture_controller = new GestureController (CLOSE_WINDOW, this, wm);
+        gesture_controller = new GestureController (CLOSE_WINDOW, wm);
         gesture_controller.enable_scroll (this, VERTICAL);
+        add_gesture_controller (gesture_controller);
 
         window.unmanaged.connect (unmanaged);
         window.notify["fullscreen"].connect (check_shadow_requirements);

src/Widgets/WindowOverview.vala

@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: GPL-3.0-or-later
  */
 
-public class Gala.WindowOverview : ActorTarget, ActivatableComponent {
+public class Gala.WindowOverview : ActorTarget, RootTarget, ActivatableComponent {
     private const int BORDER = 10;
     private const int TOP_GAP = 30;
     private const int BOTTOM_GAP = 100;
@@ -26,9 +26,10 @@ public class Gala.WindowOverview : ActorTarget, ActivatableComponent {
     construct {
         visible = false;
         reactive = true;
-        gesture_controller = new GestureController (MULTITASKING_VIEW, this, wm) {
+        gesture_controller = new GestureController (MULTITASKING_VIEW, wm) {
             enabled = false
         };
+        add_gesture_controller (gesture_controller);
     }
 
 

src/Widgets/WindowSwitcher/WindowSwitcher.vala

@@ -7,7 +7,7 @@
  * SPDX-License-Identifier: GPL-3.0-or-later
  */
 
-public class Gala.WindowSwitcher : CanvasActor, GestureTarget {
+public class Gala.WindowSwitcher : CanvasActor, GestureTarget, RootTarget {
     public const int ICON_SIZE = 64;
     public const int WRAPPER_PADDING = 12;
 
@@ -60,13 +60,14 @@ public class Gala.WindowSwitcher : CanvasActor, GestureTarget {
     construct {
         style_manager = Drawing.StyleManager.get_instance ();
 
-        gesture_controller = new GestureController (SWITCH_WINDOWS, this, wm) {
+        gesture_controller = new GestureController (SWITCH_WINDOWS, wm) {
             overshoot_upper_clamp = int.MAX,
             overshoot_lower_clamp = int.MIN,
             snap = false
         };
         gesture_controller.enable_touchpad ();
         gesture_controller.notify["recognizing"].connect (recognizing_changed);
+        add_gesture_controller (gesture_controller);
 
         container = new Clutter.Actor () {
             reactive = true,

src/Zoom.vala

@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: GPL-3.0-or-later
  */
 
-public class Gala.Zoom : Object, GestureTarget {
+public class Gala.Zoom : Object, GestureTarget, RootTarget {
     private const float MIN_ZOOM = 1.0f;
     private const float MAX_ZOOM = 10.0f;
     private const float SHORTCUT_DELTA = 0.5f;
@@ -34,10 +34,11 @@ public class Gala.Zoom : Object, GestureTarget {
         display.add_keybinding ("zoom-in", schema, Meta.KeyBindingFlags.NONE, (Meta.KeyHandlerFunc) zoom_in);
         display.add_keybinding ("zoom-out", schema, Meta.KeyBindingFlags.NONE, (Meta.KeyHandlerFunc) zoom_out);
 
-        gesture_controller = new GestureController (ZOOM, this, wm) {
+        gesture_controller = new GestureController (ZOOM, wm) {
             snap = false
         };
         gesture_controller.enable_touchpad ();
+        add_gesture_controller (gesture_controller);
 
         behavior_settings = new GLib.Settings ("io.elementary.desktop.wm.behavior");
 

src/meson.build

@@ -42,6 +42,7 @@ gala_bin_sources = files(
     'Gestures/GestureSettings.vala',
     'Gestures/GestureTarget.vala',
     'Gestures/PropertyTarget.vala',
+    'Gestures/RootTarget.vala',
     'Gestures/ScrollBackend.vala',
     'Gestures/SpringTimeline.vala',
     'Gestures/ToucheggBackend.vala',