box-layout: Animate layout properties

Use the newly added animation support inside LayoutManager to animate
between state changes of the BoxLayout properties.

The implementation is based on equivalent code from Mx, written by:

  Thomas Wood <thomas.wood@intel.com>

clutter/clutter-box-layout.c

@@ -94,8 +94,11 @@ struct _ClutterBoxLayoutPrivate
 
   guint spacing;
 
+  GHashTable *allocations;
+
   guint is_vertical   : 1;
   guint is_pack_start : 1;
+  guint is_animating  : 1;
 };
 
 struct _ClutterBoxChild
@@ -169,6 +172,7 @@ box_child_set_align (ClutterBoxChild     *self,
       ClutterLayoutManager *layout;
 
       layout = clutter_layout_meta_get_manager (CLUTTER_LAYOUT_META (self));
+      clutter_layout_manager_begin_animation (layout, 500, CLUTTER_EASE_OUT_CUBIC);
       clutter_layout_manager_layout_changed (layout);
 
       if (x_changed)
@@ -205,6 +209,7 @@ box_child_set_fill (ClutterBoxChild *self,
       ClutterLayoutManager *layout;
 
       layout = clutter_layout_meta_get_manager (CLUTTER_LAYOUT_META (self));
+      clutter_layout_manager_begin_animation (layout, 500, CLUTTER_EASE_OUT_CUBIC);
       clutter_layout_manager_layout_changed (layout);
 
       if (x_changed)
@@ -226,6 +231,7 @@ box_child_set_expand (ClutterBoxChild *self,
       self->expand = expand;
 
       layout = clutter_layout_meta_get_manager (CLUTTER_LAYOUT_META (self));
+      clutter_layout_manager_begin_animation (layout, 500, CLUTTER_EASE_OUT_CUBIC);
       clutter_layout_manager_layout_changed (layout);
 
       g_object_notify (G_OBJECT (self), "expand");
@@ -698,14 +704,6 @@ allocate_box_child (ClutterBoxLayout       *self,
 
       child_box.x1 = 0;
       child_box.x2 = floorf (avail_width + 0.5);
-
-      allocate_fill (child, &child_box, box_child);
-      clutter_actor_allocate (child, &child_box, flags);
-
-      if (box_child->expand)
-        *position += (child_nat + priv->spacing + extra_space);
-      else
-        *position += (child_nat + priv->spacing);
     }
   else
     {
@@ -721,15 +719,64 @@ allocate_box_child (ClutterBoxLayout       *self,
 
       child_box.y1 = 0;
       child_box.y2 = floorf (avail_height + 0.5);
-
-      allocate_fill (child, &child_box, box_child);
-      clutter_actor_allocate (child, &child_box, flags);
-
-      if (box_child->expand)
-        *position += (child_nat + priv->spacing + extra_space);
-      else
-        *position += (child_nat + priv->spacing);
     }
+
+  allocate_fill (child, &child_box, box_child);
+
+  if (priv->is_animating)
+    {
+      ClutterLayoutManager *manager = CLUTTER_LAYOUT_MANAGER (self);
+      ClutterActorBox *start = NULL;
+      ClutterActorBox end = { 0, };
+      gdouble p;
+
+      p = clutter_layout_manager_get_animation_progress (manager);
+
+      start = g_hash_table_lookup (priv->allocations, child);
+      if (start == NULL)
+        {
+          /* if there is no allocation available then the child has just
+           * been added to the container; we put it in the final state
+           * and store its allocation for later
+           */
+          start = clutter_actor_box_copy (&child_box);
+          g_hash_table_insert (priv->allocations, child, start);
+
+          goto do_allocate;
+        }
+
+      end = child_box;
+
+      /* interpolate between the initial and final values */
+      clutter_actor_box_interpolate (start, &end, p, &child_box);
+
+      CLUTTER_NOTE (ANIMATION,
+                    "Animate { %.1f, %.1f, %.1f, %.1f }\t"
+                     "%.3f * { %.1f, %.1f, %.1f, %.1f }\t"
+                         "-> { %.1f, %.1f, %.1f, %.1f }",
+                    start->x1, start->y1,
+                    start->x2, start->y2,
+                    p,
+                    child_box.x1, child_box.y1,
+                    child_box.x2, child_box.y2,
+                    end.x1, end.y1,
+                    end.x2, end.y2);
+    }
+  else
+    {
+      ClutterActorBox *start = clutter_actor_box_copy (&child_box);
+
+      /* store the allocation for later animations */
+      g_hash_table_replace (priv->allocations, child, start);
+    }
+
+do_allocate:
+  clutter_actor_allocate (child, &child_box, flags);
+
+  if (box_child->expand)
+    *position += (child_nat + priv->spacing + extra_space);
+  else
+    *position += (child_nat + priv->spacing);
 }
 
 static void
@@ -887,6 +934,37 @@ clutter_box_layout_allocate (ClutterLayoutManager   *layout,
   g_list_free (children);
 }
 
+static void
+clutter_box_layout_begin_animation (ClutterLayoutManager *manager,
+                                    guint                 duration,
+                                    gulong                easing)
+{
+  ClutterBoxLayoutPrivate *priv = CLUTTER_BOX_LAYOUT (manager)->priv;
+  ClutterLayoutManagerClass *parent_class;
+
+  if (priv->is_animating)
+    return;
+
+  priv->is_animating = TRUE;
+
+  /* we want the default implementation */
+  parent_class = CLUTTER_LAYOUT_MANAGER_CLASS (clutter_box_layout_parent_class);
+  parent_class->begin_animation (manager, duration, easing);
+}
+
+static void
+clutter_box_layout_end_animation (ClutterLayoutManager *manager)
+{
+  ClutterBoxLayoutPrivate *priv = CLUTTER_BOX_LAYOUT (manager)->priv;
+  ClutterLayoutManagerClass *parent_class;
+
+  priv->is_animating = FALSE;
+
+  /* we want the default implementation */
+  parent_class = CLUTTER_LAYOUT_MANAGER_CLASS (clutter_box_layout_parent_class);
+  parent_class->end_animation (manager);
+}
+
 static void
 clutter_box_layout_set_property (GObject      *gobject,
                                  guint         prop_id,
@@ -943,6 +1021,16 @@ clutter_box_layout_get_property (GObject    *gobject,
     }
 }
 
+static void
+clutter_box_layout_finalize (GObject *gobject)
+{
+  ClutterBoxLayoutPrivate *priv = CLUTTER_BOX_LAYOUT (gobject)->priv;
+
+  g_hash_table_destroy (priv->allocations);
+
+  G_OBJECT_CLASS (clutter_box_layout_parent_class)->finalize (gobject);
+}
+
 static void
 clutter_box_layout_class_init (ClutterBoxLayoutClass *klass)
 {
@@ -954,6 +1042,7 @@ clutter_box_layout_class_init (ClutterBoxLayoutClass *klass)
 
   gobject_class->set_property = clutter_box_layout_set_property;
   gobject_class->get_property = clutter_box_layout_get_property;
+  gobject_class->finalize = clutter_box_layout_finalize;
 
   layout_class->get_preferred_width =
     clutter_box_layout_get_preferred_width;
@@ -963,6 +1052,8 @@ clutter_box_layout_class_init (ClutterBoxLayoutClass *klass)
   layout_class->set_container = clutter_box_layout_set_container;
   layout_class->get_child_meta_type =
     clutter_box_layout_get_child_meta_type;
+  layout_class->begin_animation = clutter_box_layout_begin_animation;
+  layout_class->end_animation = clutter_box_layout_end_animation;
 
   g_type_class_add_private (klass, sizeof (ClutterBoxLayoutPrivate));
 
@@ -1022,6 +1113,11 @@ clutter_box_layout_init (ClutterBoxLayout *layout)
   priv->is_vertical = FALSE;
   priv->is_pack_start = FALSE;
   priv->spacing = 0;
+
+  priv->allocations =
+    g_hash_table_new_full (NULL, NULL,
+                           NULL,
+                           (GDestroyNotify) clutter_actor_box_free);
 }
 
 /**
@@ -1065,7 +1161,7 @@ clutter_box_layout_set_spacing (ClutterBoxLayout *layout,
       priv->spacing = spacing;
 
       manager = CLUTTER_LAYOUT_MANAGER (layout);
-      clutter_layout_manager_layout_changed (manager);
+      clutter_layout_manager_begin_animation (manager, 500, CLUTTER_EASE_OUT_CUBIC);
 
       g_object_notify (G_OBJECT (layout), "spacing");
     }
@@ -1116,7 +1212,7 @@ clutter_box_layout_set_vertical (ClutterBoxLayout *layout,
       priv->is_vertical = vertical ? TRUE : FALSE;
 
       manager = CLUTTER_LAYOUT_MANAGER (layout);
-      clutter_layout_manager_layout_changed (manager);
+      clutter_layout_manager_begin_animation (manager, 500, CLUTTER_EASE_OUT_CUBIC);
 
       g_object_notify (G_OBJECT (layout), "vertical");
     }
@@ -1170,7 +1266,7 @@ clutter_box_layout_set_pack_start (ClutterBoxLayout *layout,
       priv->is_pack_start = pack_start ? TRUE : FALSE;
 
       manager = CLUTTER_LAYOUT_MANAGER (layout);
-      clutter_layout_manager_layout_changed (manager);
+      clutter_layout_manager_begin_animation (manager, 500, CLUTTER_EASE_OUT_CUBIC);
 
       g_object_notify (G_OBJECT (layout), "pack-start");
     }