animatable: Deprecate and replace animate_property()

The animate_property() method of the Animatable interface is far less
than optimal:

  • it has a direct reference to ClutterAnimation;
  • it has an interval decomposed as two values.

These issues tie the Animatable interface with the Animation object,
even though it's neither necessary nor future-proof.

Let's introduce a new method, interpolate_value(), which does not
reference ClutterAnimation and uses a ClutterInterval to express the
initial and final states.

clutter/clutter-animatable.c

@@ -84,6 +84,9 @@ clutter_animatable_default_init (ClutterAnimatableInterface *iface)
  *   be applied to the #ClutterAnimatable, and %FALSE otherwise
  *
  * Since: 1.0
+ *
+ * Deprecated: 1.8: Use clutter_animatable_interpolate_value()
+ *   instead
  */
 gboolean
 clutter_animatable_animate_property (ClutterAnimatable *animatable,
@@ -94,6 +97,7 @@ clutter_animatable_animate_property (ClutterAnimatable *animatable,
                                      gdouble            progress,
                                      GValue            *value)
 {
+  ClutterAnimatableIface *iface;
   gboolean res;
 
   g_return_val_if_fail (CLUTTER_IS_ANIMATABLE (animatable), FALSE);
@@ -107,14 +111,26 @@ clutter_animatable_animate_property (ClutterAnimatable *animatable,
                         G_VALUE_TYPE (value) == G_VALUE_TYPE (final_value),
                         FALSE);
 
-  res =
+  iface = CLUTTER_ANIMATABLE_GET_IFACE (animatable);
-    CLUTTER_ANIMATABLE_GET_IFACE (animatable)->animate_property (animatable,
+  if (iface->animate_property == NULL)
-                                                                 animation,
+    {
-                                                                 property_name,
+      ClutterInterval *interval;
-                                                                 initial_value,
+
-                                                                 final_value,
+      interval = clutter_animation_get_interval (animation, property_name);
-                                                                 progress,
+      if (interval == NULL)
-                                                                 value);
+        return FALSE;
+
+      res = clutter_animatable_interpolate_value (animatable, property_name,
+                                                  interval,
+                                                  progress,
+                                                  value);
+    }
+  else
+    res = iface->animate_property (animatable, animation,
+                                   property_name,
+                                   initial_value, final_value,
+                                   progress,
+                                   value);
 
   return res;
 }
@@ -207,3 +223,33 @@ clutter_animatable_set_final_state (ClutterAnimatable *animatable,
   else
     g_object_set_property (G_OBJECT (animatable), property_name, value);
 }
+
+gboolean
+clutter_animatable_interpolate_value (ClutterAnimatable *animatable,
+                                      const gchar       *property_name,
+                                      ClutterInterval   *interval,
+                                      gdouble            progress,
+                                      GValue            *value)
+{
+  ClutterAnimatableIface *iface;
+
+  g_return_val_if_fail (CLUTTER_IS_ANIMATABLE (animatable), FALSE);
+  g_return_val_if_fail (property_name != NULL, FALSE);
+  g_return_val_if_fail (CLUTTER_IS_INTERVAL (interval), FALSE);
+  g_return_val_if_fail (value != NULL, FALSE);
+
+  CLUTTER_NOTE (ANIMATION, "Interpolating '%s' (progress: %.3f)",
+                property_name,
+                progress);
+
+  iface = CLUTTER_ANIMATABLE_GET_IFACE (animatable);
+  if (iface->interpolate_value != NULL)
+    {
+      return iface->interpolate_value (animatable, property_name,
+                                       interval,
+                                       progress,
+                                       value);
+    }
+  else
+    return clutter_interval_compute_value (interval, progress, value);
+}

clutter/clutter-animatable.h

@@ -53,13 +53,15 @@ typedef struct _ClutterAnimatableIface          ClutterAnimatableIface;
 /**
  * ClutterAnimatableIface:
  * @animate_property: virtual function for custom interpolation of a
- *   property
+ *   property. This virtual function is deprecated
  * @find_property: virtual function for retrieving the #GParamSpec of
  *   an animatable property
  * @get_initial_state: virtual function for retrieving the initial
  *   state of an animatable property
  * @set_final_state: virtual function for setting the state of an
  *   animatable property
+ * @interpolate_value: virtual function for interpolating the progress
+ *   of a property
  *
  * Base interface for #GObject<!-- -->s that can be animated by a
  * a #ClutterAnimation.
@@ -87,10 +89,16 @@ struct _ClutterAnimatableIface
   void        (* set_final_state)   (ClutterAnimatable *animatable,
                                      const gchar       *property_name,
                                      const GValue      *value);
+  gboolean    (* interpolate_value) (ClutterAnimatable *animatable,
+                                     const gchar       *property_name,
+                                     ClutterInterval   *interval,
+                                     gdouble            progress,
+                                     GValue            *value);
 };
 
 GType clutter_animatable_get_type (void) G_GNUC_CONST;
 
+#ifndef CLUTTER_DISABLE_DEPRECATED
 gboolean    clutter_animatable_animate_property  (ClutterAnimatable *animatable,
                                                   ClutterAnimation  *animation,
                                                   const gchar       *property_name,
@@ -98,6 +106,7 @@ gboolean    clutter_animatable_animate_property  (ClutterAnimatable *animatable,
                                                   const GValue      *final_value,
                                                   gdouble            progress,
                                                   GValue            *value);
+#endif /* CLUTTER_DISABLE_DEPRECATED */
 
 GParamSpec *clutter_animatable_find_property     (ClutterAnimatable *animatable,
                                                   const gchar       *property_name);
@@ -107,6 +116,11 @@ void        clutter_animatable_get_initial_state (ClutterAnimatable *animatable,
 void        clutter_animatable_set_final_state   (ClutterAnimatable *animatable,
                                                   const gchar       *property_name,
                                                   const GValue      *value);
+gboolean    clutter_animatable_interpolate_value (ClutterAnimatable *animatable,
+                                                  const gchar       *property_name,
+                                                  ClutterInterval   *interval,
+                                                  gdouble            progress,
+                                                  GValue            *value);
 
 G_END_DECLS