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Since version 1.0, Clutter provides the ClutterAnimation API
and the clutter_actor_animate() family of functions as replacements
for the ClutterEffectTemplate and
clutter_effect_* API for creating simple, one-off animations.
clutter_actor_animate()Prior to Clutter 1.0, the way to create simple, one-off animations involving a single actor was the ClutterEffect API. The major downside of this API was that to abstract the duration and easing function of the animation the application developer had to create a ClutterEffectTemplate and keep it around for the duration of the application.
The clutter_actor_animate() function performs all of the
memory management that was delegated to the
ClutterEffectTemplate, freeing the developer
from having to deal with object bookkeeping.
Another downside of the ClutterEffect API is that every possible animation has its own function (scaling, opacity, rotation, movement, etc.), and new functions cannot be added outside of Clutter.
Example 1. Effect example
The following code shows a simple animation using the ClutterEffect API. It animates an actor linearly in 500 milliseconds, by moving it to the (100, 100) coordinates while fading it out.
ClutterEffectTemplate *tmpl;
tmpl = clutter_effect_template_new_for_duration (500, clutter_ramp_inc_func);
clutter_effect_move (tmpl, actor, 100, 100, NULL, NULL);
clutter_effect_fade (tmpl, actor, 0, NULL, NULL);
g_object_unref (tmpl);
The clutter_actor_animate() function will implicitely
create a ClutterAnimation with the passed duration and easing
mode, and will bind all the passed properties. All readable and
writable properties specified by a ClutterActor are animatable
through clutter_actor_animate().
Example 2. Animation example
The following code shows the clutter_actor_animate() call
equivalent to the previous ClutterEffect example.
clutter_actor_animate (actor, CLUTTER_LINEAR, 500,
"x", 100.0,
"y", 100.0,
"opacity", 0,
NULL);
The ClutterEffect API provided a way to be notified of the
effect completion. Since the clutter_actor_animate() function creates
a ClutterAnimation instance it's possible to use the
“completed” signal for the same notification.
Example 3. Effect complete example
The following code shows how to receive notification of the completion of the animation.
static void
on_fade_complete (ClutterActor *actor,
gpointer data)
{
clutter_actor_hide (actor);
}
ClutterEffectTemplate *tmpl;
tmpl = clutter_effect_template_new_for_duration (500, clutter_ramp_inc_func);
clutter_effect_fade (tmpl, actor, 0, on_fade_complete, NULL);
g_object_unref (tmpl);
The clutter_actor_animate() function also has a convenience
wrapper that allows to inline the signal connection:
Example 4. Animation completed example
The following code shows how to get the same notification as the example above.
ClutterAnimation *animation;
animation = clutter_actor_animate (actor, CLUTTER_LINEAR, 500,
"opacity", 0,
NULL);
g_signal_connect_swapped (animation,
"completed", G_CALLBACK (clutter_actor_hide),
actor);
/* OR */
clutter_actor_animate (actor, CLUTTER_LINEAR, 500,
"opacity", 0,
"signal-swapped::completed", clutter_actor_hide, actor,
NULL);