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docs: Add sub-classing notes on ActorMeta and Constraint

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This commit is contained in:
Emmanuele Bassi 2010-09-17 14:54:31 +01:00
parent f7e8b47113
commit 68da998c9b
2 changed files with 32 additions and 2 deletions
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8
clutter/clutter-actor-meta.c
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@ -5,10 +5,14 @@
* @See_Also: #ClutterAction, #ClutterConstraint
*
* #ClutterActorMeta is an abstract class providing a common API for
* modifiers of #ClutterActor
* modifiers of #ClutterActor behaviour, appearance or layout.
*
* A #ClutterActorMeta can only be owned by a single #ClutterActor at
* any time
* any time.
*
* Every sub-class of #ClutterActorMeta should check if the
* #ClutterActorMeta:enabled property is set to %TRUE before applying
* any kind of modification.
*
* #ClutterActorMeta is available since Clutter 1.4
*/

26
clutter/clutter-constraint.c
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@ -13,6 +13,32 @@
* allocation of the actor to which they are applied by overriding the
* <function>update_allocation()</function> virtual function.
*
* <refsect2 id="ClutterConstraint-implementation">
* <title>Implemting a ClutterConstraint</title>
* <para>Creating a sub-class of #ClutterConstraint requires the
* implementation of the <function>update_allocation()</function>
* virtual function.</para>
* <para>The <function>update_allocation()</function> virtual function
* is called during the allocation sequence of a #ClutterActor, and
* allows any #ClutterConstraint attached to that actor to modify the
* allocation before it is passed to the <function>allocate()</function>
* implementation.</para>
* <para>The #ClutterActorBox passed to the
* <function>update_allocation()</function> implementation contains the
* original allocation of the #ClutterActor, plus the eventual modifications
* applied by the other #ClutterConstraint<!-- -->s.</para>
* <note><para>Constraints are queried in the same order as they were
* applied using clutter_actor_add_constraint() or
* clutter_actor_add_constraint_with_name().</para></note>
* <para>It is not necessary for a #ClutterConstraint sub-class to chain
* up to the parent's implementation.</para>
* <para>If a #ClutterConstraint is parametrized - i.e. if it contains
* properties that affect the way the constraint is implemented - it should
* call clutter_actor_queue_relayout() on the actor to which it is attached
* to whenever any parameter is changed. The actor to which it is attached
* can be recovered at any point using clutter_actor_meta_get_actor().</para>
* </refsect2>
*
* #ClutterConstraint is available since Clutter 1.4
*/