Add ActorBox animation methods

ClutterActorBox should have an interpolate() method that allows to
compute the intermediate values between two states, given a progress
value, e.g.:

        clutter_actor_box_interpolate (start, end, alpha, &result);

Another utility method, useful for layout managers, is a modifier
that clamps the members of the actor box to the nearest integer
value.

clutter/clutter-actor.c

@@ -8317,6 +8317,53 @@ clutter_actor_box_from_vertices (ClutterActorBox     *box,
   box->y2 = y_2;
 }
 
+/**
+ * clutter_actor_box_interpolate:
+ * @initial: the initial #ClutterActorBox
+ * @final: the final #ClutterActorBox
+ * @progress: the interpolation progress
+ * @result: (out): return location for the interpolation
+ *
+ * Interpolates between @initial and @final #ClutterActorBox<!-- -->es
+ * using @progress
+ *
+ * Since: 1.2
+ */
+void
+clutter_actor_box_interpolate (const ClutterActorBox *initial,
+                               const ClutterActorBox *final,
+                               gdouble                progress,
+                               ClutterActorBox       *result)
+{
+  g_return_if_fail (initial != NULL);
+  g_return_if_fail (final != NULL);
+  g_return_if_fail (result != NULL);
+
+  result->x1 = initial->x1 + (final->x1 - initial->x1) * progress;
+  result->y1 = initial->y1 + (final->y1 - initial->y1) * progress;
+  result->x2 = initial->x2 + (final->x2 - initial->x2) * progress;
+  result->y2 = initial->y2 + (final->y2 - initial->y2) * progress;
+}
+
+/**
+ * clutter_actor_box_clamp_to_pixel:
+ * @box: (inout): the #ClutterActorBox to clamp
+ *
+ * Clamps the components of @box to the nearest integer
+ *
+ * Since: 1.2
+ */
+void
+clutter_actor_box_clamp_to_pixel (ClutterActorBox *box)
+{
+  g_return_if_fail (box != NULL);
+
+  box->x1 = floorf (box->x1 + 0.5);
+  box->y1 = floorf (box->y1 + 0.5);
+  box->x2 = floorf (box->x2 + 0.5);
+  box->y2 = floorf (box->y2 + 0.5);
+}
+
 /******************************************************************************/
 
 struct _ShaderData

clutter/clutter-types.h

@@ -153,6 +153,11 @@ gboolean         clutter_actor_box_contains      (const ClutterActorBox *box,
                                                   gfloat                 y);
 void             clutter_actor_box_from_vertices (ClutterActorBox       *box,
                                                   const ClutterVertex    verts[]);
+void             clutter_actor_box_interpolate   (const ClutterActorBox *initial,
+                                                  const ClutterActorBox *final,
+                                                  gdouble                progress,
+                                                  ClutterActorBox       *result);
+void             clutter_actor_box_clamp_to_pixel (ClutterActorBox       *box);
 
 /**
  * ClutterGeometry:

doc/reference/clutter/clutter-sections.txt

@@ -414,6 +414,8 @@ clutter_actor_box_get_size
 clutter_actor_box_get_area
 clutter_actor_box_contains
 clutter_actor_box_from_vertices
+clutter_actor_box_clamp_to_pixel
+clutter_actor_box_interpolate
 
 <SUBSECTION>
 ClutterVertex