mutter/doc/reference/migrating-ClutterAnimation.xml
Emmanuele Bassi 67bf902022 Move API reference down one level
Since we only have one API reference, we can drop the clutter/
sub-level, and have all the files under doc/reference.
2015-05-19 15:27:30 +01:00

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XML

<?xml version="1.0"?>
<!DOCTYPE chapter PUBLIC
"-//OASIS//DTD DocBook XML V4.3//EN"
"http://www.oasis-open.org/docbook/xml/4.3/docbookx.dtd" [
]>
<chapter id="migrating-ClutterAnimation">
<chapterinfo>
<author>
<firstname>Emmanuele</firstname>
<surname>Bassi</surname>
<affiliation>
<address>
<email>ebassi@gnome.org</email>
</address>
</affiliation>
</author>
</chapterinfo>
<title>Migrating from ClutterAnimation</title>
<para>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.</para>
<para>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.</para>
<para>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.</para>
<para>For instance, the following #ClutterAnimation set up:</para>
<informalexample><programlisting language="C"><![CDATA[
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);
]]></programlisting></informalexample>
<para>Can be replaced by #ClutterPropertyTransition:</para>
<informalexample><programlisting language="C"><![CDATA[
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));
]]></programlisting></informalexample>
<para>It is important to note that only #ClutterAnimatable implementations
can be used directly with #ClutterTransition.</para>
<para>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.</para>
<section>
<title>Migrating clutter_actor_animate()</title>
<para>#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:</para>
<informalexample><programlisting language="C"><![CDATA[
clutter_actor_animate (actor, CLUTTER_EASE_OUT_BOUNCE, 500,
"x", new_x_position,
"y", new_y_position,
"opacity", 255,
NULL);
]]></programlisting></informalexample>
<para>Can be replaced by the following:</para>
<informalexample><programlisting language="C"><![CDATA[
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);
]]></programlisting></informalexample>
<para>The default easing duration for the 1.0 API series is set to 0,
which means no transition at all.</para>
<para>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:</para>
<informalexample><programlisting language="C"><![CDATA[
clutter_actor_save_easing_state (actor);
clutter_actor_set_easing_duration (actor, 500);
clutter_actor_set_opacity (actor, 255);
clutter_actor_save_easing_state (actor);
clutter_actor_set_easing_delay (actor, 500);
clutter_actor_set_easing_duration (actor, 500);
clutter_actor_set_size (actor, width, height);
clutter_actor_restore_easing_state (actor);
clutter_actor_restore_easing_state (actor);
]]></programlisting></informalexample>
<para>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 <emphasis>width</emphasis> and
<emphasis>height</emphasis>.</para>
</section>
</chapter>