Migrating from ClutterAnimation

Emmanuele Bassi



          

        

The ClutterAnimation class, along with the ClutterActor wrappers clutter_actor_animate(), clutter_actor_animate_with_timeline() and clutter_actor_animate_with_alpha(), has been deprecated in Clutter 1.12, and should not be used in newly written code.

The direct replacement for a ClutterAnimation is the ClutterPropertyTransition class, which allows the transition of a single GObject property from an initial value to a final value over a user-defined time using a user-defined easing curve.

The ClutterPropertyTransition class inherits from ClutterTransition, which allows setting the transition interval, as well as the animatable instance to be transitioned; and from ClutterTimeline, which allows setting the duration and easing curve of the transition.

For instance, the following ClutterAnimation set up:

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
ClutterAnimation *animation = clutter_animation_new ();

clutter_animation_set_mode (animation, CLUTTER_EASE_OUT_CUBIC);
clutter_animation_set_duration (animation, 2500);

/* object_to_animate is set elsewhere */
clutter_animation_set_object (animation, object_to_animate);

ClutterInterval *interval = clutter_interval_new (G_TYPE_FLOAT, 0.0, 100.0);

/* property_name is set elsewhere */
clutter_animation_bind_interval (animation, property_name, interval);

ClutterTimeline *timeline = clutter_animation_get_timeline (animation);
clutter_timeline_start (timeline);

Can be replaced by ClutterPropertyTransition:

1
2
3
4
5
6
7
8
9
10
11
12
ClutterTransition *transition = clutter_property_transition_new (property_name);

clutter_timeline_set_progress_mode (CLUTTER_TIMELINE (transition),
                                    CLUTTER_EASE_OUT_CUBIC);
clutter_timeline_set_duration (CLUTTER_TIMELINE (transition), 2000);

clutter_transition_set_animatable (transition, object_to_animate);

clutter_transition_set_from (transition, G_TYPE_FLOAT, 0.0);
clutter_transition_set_to (transition, G_TYPE_FLOAT, 100.0);

clutter_timeline_start (CLUTTER_TIMELINE (transition));

It is important to note that only ClutterAnimatable implementations can be used directly with ClutterTransition.

A ClutterPropertyTransition can only animate a single property; if more than one property transition is required, you can use the ClutterTransitionGroup class to group the transitions together.

ClutterActor animatable properties can use implicit transitions through their setter functions. The duration and easing curve of the animation is controlled by clutter_actor_set_easing_duration() and by clutter_actor_set_easing_mode(), respectively; for instance, the equivalent of the following clutter_actor_animate() call:

1
2
3
4
5
clutter_actor_animate (actor, CLUTTER_EASE_OUT_BOUNCE, 500,
                       "x", new_x_position,
                       "y", new_y_position,
                       "opacity", 255,
                       NULL);

Can be replaced by the following:

1
2
3
4
clutter_actor_set_easing_mode (actor, CLUTTER_EASE_OUT_BOUNCE);
clutter_actor_set_easing_duration (actor, 500);
clutter_actor_set_position (actor, new_x_position, new_y_position);
clutter_actor_set_opacity (actor, 255);

The default easing duration for the 1.0 API series is set to 0, which means no transition at all.

It is possible to set the easing state of a ClutterActor to its default values by using clutter_actor_save_easing_state(), and return to the previous values by calling clutter_actor_restore_easing_state() instead. The easing state affects all the animatable properties that are modified after changing it; so, for instance:

The animation above will implicitly transition the opacity from its current value to 255 in 500 milliseconds using the default easing curve; at the same time, the size of the actor will be transitioned in 500 milliseconds after a delay of 500 milliseconds to the new size stored in the variables width and height.