GestureTarget: Require ClutterActor only for RootTarget

lib/Gestures/ActorTarget.vala

@@ -11,12 +11,6 @@
  * If a new child (or target via {@link add_target}) is added, its progress will be synced.
  */
 public class Gala.ActorTarget : Clutter.Actor, GestureTarget {
-    public Clutter.Actor? actor {
-        get {
-            return this;
-        }
-    }
-
     public bool animating { get { return ongoing_animations > 0; } }
 
     private double[] current_progress;

lib/Gestures/GestureTarget.vala

@@ -13,11 +13,5 @@ public interface Gala.GestureTarget : Object {
         END
     }
 
-    /**
-     * The actor manipulated by the gesture. The associated frame clock
-     * will be used for animation timelines.
-     */
-    public abstract Clutter.Actor? actor { get; }
-
     public virtual void propagate (UpdateType update_type, GestureAction action, double progress) { }
 }

lib/Gestures/PropertyTarget.vala

@@ -7,27 +7,34 @@
 
 public class Gala.PropertyTarget : Object, GestureTarget {
     public GestureAction action { get; construct; }
-
-    //we don't want to hold a strong reference to the actor because we might've been added to it which would form a reference cycle
-    private weak Clutter.Actor? _actor;
-    public Clutter.Actor? actor { get { return _actor; } }
-
+    // Don't take a reference since we are most of the time owned by the target
+    public weak Object? target { get; private set; }
     public string property { get; construct; }
 
     public Clutter.Interval interval { get; construct; }
 
-    public PropertyTarget (GestureAction action, Clutter.Actor actor, string property, Type value_type, Value from_value, Value to_value) {
+    public PropertyTarget (GestureAction action, Object target, string property, Type value_type, Value from_value, Value to_value) {
         Object (action: action, property: property, interval: new Clutter.Interval.with_values (value_type, from_value, to_value));
 
-        _actor = actor;
-        _actor.destroy.connect (() => _actor = null);
+        this.target = target;
+        this.target.weak_ref (on_target_disposed);
+    }
+
+    ~PropertyTarget () {
+        if (target != null) {
+            target.weak_unref (on_target_disposed);
+        }
+    }
+
+    private void on_target_disposed () {
+        target = null;
     }
 
     public override void propagate (UpdateType update_type, GestureAction action, double progress) {
-        if (update_type != UPDATE || action != this.action) {
+        if (target == null || update_type != UPDATE || action != this.action) {
             return;
         }
 
-        actor.set_property (property, interval.compute (progress));
+        target.set_property (property, interval.compute (progress));
     }
 }

lib/Gestures/RootTarget.vala

@@ -6,6 +6,12 @@
  */
 
 public interface Gala.RootTarget : Object, GestureTarget {
+    /**
+     * The actor manipulated by the gesture. The associated frame clock
+     * will be used for animation timelines.
+     */
+    public abstract Clutter.Actor? actor { get; }
+
     public void add_gesture_controller (GestureController controller) requires (controller.target == null) {
         controller.attached (this);
         weak_ref (controller.detached);

src/ShellClients/PanelWindow.vala

@@ -8,6 +8,7 @@
 public class Gala.PanelWindow : ShellWindow, RootTarget {
     private static HashTable<Meta.Window, Meta.Strut?> window_struts = new HashTable<Meta.Window, Meta.Strut?> (null, null);
 
+    public Clutter.Actor? actor { get { return (Clutter.Actor) window.get_compositor_private (); } }
     public WindowManager wm { get; construct; }
     public Pantheon.Desktop.Anchor anchor { get; construct set; }
 

src/ShellClients/ShellClientsManager.vala

@@ -20,8 +20,6 @@ public class Gala.ShellClientsManager : Object, GestureTarget {
         return instance;
     }
 
-    public Clutter.Actor? actor { get { return wm.stage; } }
-
     public WindowManager wm { get; construct; }
 
     private NotificationsClient notifications_client;

src/ShellClients/ShellWindow.vala

@@ -6,7 +6,6 @@
  */
 
 public class Gala.ShellWindow : PositionedWindow, GestureTarget {
-    public Clutter.Actor? actor { get { return window_actor; } }
     public bool restore_previous_x11_region { private get; set; default = false; }
 
     private Meta.WindowActor window_actor;

src/Widgets/MultitaskingView/MultitaskingView.vala

@@ -26,6 +26,7 @@ public class Gala.MultitaskingView : ActorTarget, RootTarget, ActivatableCompone
     private GestureController workspaces_gesture_controller;
     private GestureController multitasking_gesture_controller;
 
+    public Clutter.Actor? actor { get { return this; } }
     public WindowManagerGala wm { get; construct; }
 
     private Meta.Display display;

src/Widgets/MultitaskingView/WindowClone.vala

@@ -27,6 +27,7 @@ public class Gala.WindowClone : ActorTarget, RootTarget {
      */
     public signal void request_reposition ();
 
+    public Clutter.Actor? actor { get { return this; } }
     public WindowManager wm { get; construct; }
     public Meta.Window window { get; construct; }
 

src/Widgets/WindowOverview.vala

@@ -10,6 +10,7 @@ public class Gala.WindowOverview : ActorTarget, RootTarget, ActivatableComponent
     private const int TOP_GAP = 30;
     private const int BOTTOM_GAP = 100;
 
+    public Clutter.Actor? actor { get { return this; } }
     public WindowManager wm { get; construct; }
 
     private GestureController gesture_controller; // Currently not used for actual touchpad gestures but only as controller