clutter: Replace ClutterActors resource-scale property with a signal

We're going to refactor resource scales, making the notification of
changes to the resource scale a lot more important than it is right now
(we won't guarantee queried scales are correct outside the paint cycle
anymore).

Having a separate signal/vfunc for this will make the difference between
the new clutter_actor_get_resource_scale() API (which can return a
guessed value) and the notification of changes to the resource scale
(which will be guaranteed to return an up-to-date value) more obvious.

So replace the "resource-scale" property of ClutterActor with a
"resource-scale-changed" signal that's emitted when the resource scale
is recalculated.

https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1276

clutter/clutter/clutter-actor.c

@@ -924,7 +924,6 @@ enum
   PROP_SCALE_X,
   PROP_SCALE_Y,
   PROP_SCALE_Z,
-  PROP_RESOURCE_SCALE,
 
   PROP_ROTATION_ANGLE_X, /* XXX:2.0 rename to rotation-x */
   PROP_ROTATION_ANGLE_Y, /* XXX:2.0 rename to rotation-y */
@@ -1005,6 +1004,7 @@ enum
   TOUCH_EVENT,
   TRANSITION_STOPPED,
   STAGE_VIEWS_CHANGED,
+  RESOURCE_SCALE_CHANGED,
 
   LAST_SIGNAL
 };
@@ -5375,16 +5375,6 @@ clutter_actor_get_property (GObject    *object,
       }
       break;
 
-    case PROP_RESOURCE_SCALE:
-      if (priv->needs_compute_resource_scale)
-        {
-          if (!clutter_actor_update_resource_scale (actor))
-            g_warning ("Getting invalid resource scale property");
-        }
-
-      g_value_set_float (value, priv->resource_scale);
-      break;
-
     case PROP_REACTIVE:
       g_value_set_boolean (value, clutter_actor_get_reactive (actor));
       break;
@@ -6678,19 +6668,6 @@ clutter_actor_class_init (ClutterActorClass *klass)
                          G_PARAM_STATIC_STRINGS |
                          CLUTTER_PARAM_ANIMATABLE);
 
-  /**
-   * ClutterActor:resource-scale:
-   *
-   * The resource-scale of the #ClutterActor if any or -1 if not available
-   */
-  obj_props[PROP_RESOURCE_SCALE] =
-    g_param_spec_float ("resource-scale",
-                        P_("Resource Scale"),
-                        P_("The Scaling factor for resources painting"),
-                        -1.0f, G_MAXFLOAT,
-                        1.0f,
-                        CLUTTER_PARAM_READABLE);
-
   /**
    * ClutterActor:rotation-angle-x:
    *
@@ -7981,6 +7958,23 @@ clutter_actor_class_init (ClutterActorClass *klass)
                   NULL, NULL, NULL,
                   G_TYPE_NONE, 0);
 
+  /**
+   * ClutterActor::resource-scale-changed:
+   * @actor: a #ClutterActor
+   *
+   * The ::resource-scale-changed signal is emitted when the resource scale
+   * value returned by clutter_actor_get_resource_scale() changes.
+   *
+   * This signal can be used to get notified about the correct resource scale
+   * when the scale had to be queried outside of the paint cycle.
+   */
+  actor_signals[RESOURCE_SCALE_CHANGED] =
+    g_signal_new (I_("resource-scale-changed"),
+                  G_TYPE_FROM_CLASS (object_class),
+                  G_SIGNAL_RUN_LAST,
+                  G_STRUCT_OFFSET (ClutterActorClass, resource_scale_changed),
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 0);
 }
 
 static void
@@ -16126,7 +16120,7 @@ clutter_actor_ensure_resource_scale (ClutterActor *self)
     return;
 
   if (clutter_actor_update_resource_scale (self))
-    g_object_notify_by_pspec (G_OBJECT (self), obj_props[PROP_RESOURCE_SCALE]);
+    g_signal_emit (self, actor_signals[RESOURCE_SCALE_CHANGED], 0);
 }
 
 gboolean

clutter/clutter/clutter-actor.h

@@ -296,6 +296,7 @@ struct _ClutterActorClass
   gboolean (* touch_event)          (ClutterActor         *self,
                                      ClutterTouchEvent    *event);
   gboolean (* has_accessible)       (ClutterActor         *self);
+  void     (* resource_scale_changed) (ClutterActor *self);
 
   /*< private >*/
   /* padding for future expansion */

clutter/clutter/clutter-text.c

@@ -187,9 +187,6 @@ struct _ClutterTextPrivate
   ClutterInputContentHintFlags input_hints;
   ClutterInputContentPurpose input_purpose;
 
-  /* Signal handler for when the :resource-scale changes */
-  gulong resource_scale_changed_id;
-
   /* bitfields */
   guint alignment               : 2;
   guint wrap                    : 1;
@@ -922,18 +919,6 @@ clutter_text_direction_changed_cb (GObject    *gobject,
   /* no need to queue a relayout: set_text_direction() will do that for us */
 }
 
-static void
-clutter_text_resource_scale_changed_cb (GObject    *gobject,
-                                        GParamSpec *pspec)
-{
-  ClutterText *self = CLUTTER_TEXT (gobject);
-  ClutterTextPrivate *priv = self->priv;
-
-  g_clear_pointer (&priv->effective_attrs, pango_attr_list_unref);
-  clutter_text_dirty_cache (self);
-  clutter_actor_queue_relayout (CLUTTER_ACTOR (gobject));
-}
-
 /*
  * clutter_text_create_layout:
  * @text: a #ClutterText
@@ -1776,7 +1761,6 @@ clutter_text_dispose (GObject *gobject)
   clutter_text_dirty_cache (self);
 
   g_clear_signal_handler (&priv->direction_changed_id, self);
-  g_clear_signal_handler (&priv->resource_scale_changed_id, self);
   g_clear_signal_handler (&priv->settings_changed_id,
                           clutter_get_default_backend ());
 
@@ -3066,6 +3050,17 @@ clutter_text_has_overlaps (ClutterActor *self)
   return clutter_text_should_draw_cursor ((ClutterText *) self);
 }
 
+static void
+clutter_text_resource_scale_changed (ClutterActor *actor)
+{
+  ClutterText *self = CLUTTER_TEXT (actor);
+  ClutterTextPrivate *priv = self->priv;
+
+  g_clear_pointer (&priv->effective_attrs, pango_attr_list_unref);
+  clutter_text_dirty_cache (self);
+  clutter_actor_queue_relayout (actor);
+}
+
 static void
 clutter_text_im_focus (ClutterText *text)
 {
@@ -3814,6 +3809,7 @@ clutter_text_class_init (ClutterTextClass *klass)
   actor_class->key_focus_in = clutter_text_key_focus_in;
   actor_class->key_focus_out = clutter_text_key_focus_out;
   actor_class->has_overlaps = clutter_text_has_overlaps;
+  actor_class->resource_scale_changed = clutter_text_resource_scale_changed;
 
   /**
    * ClutterText:buffer:
@@ -4621,11 +4617,6 @@ clutter_text_init (ClutterText *self)
                       NULL);
 
   priv->input_focus = clutter_text_input_focus_new (self);
-
-  priv->resource_scale_changed_id =
-    g_signal_connect (self, "notify::resource-scale",
-                      G_CALLBACK (clutter_text_resource_scale_changed_cb),
-                      NULL);
 }
 
 /**