ClutterBehaviour

ClutterBehaviour — Class for providing behaviours to actors

Synopsis




                    ClutterBehaviourClass;
void                clutter_behaviour_apply             (ClutterBehaviour *behave,
                                                         ClutterActor *actor);
void                clutter_behaviour_remove            (ClutterBehaviour *behave,
                                                         ClutterActor *actor);
void                clutter_behaviour_remove_all        (ClutterBehaviour *behave);
gboolean            clutter_behaviour_is_applied        (ClutterBehaviour *behave,
                                                         ClutterActor *actor);
void                (*ClutterBehaviourForeachFunc)      (ClutterBehaviour *behaviour,
                                                         ClutterActor *actor,
                                                         gpointer data);
void                clutter_behaviour_actors_foreach    (ClutterBehaviour *behave,
                                                         ClutterBehaviourForeachFunc func,
                                                         gpointer data);
GSList*             clutter_behaviour_get_actors        (ClutterBehaviour *behave);
gint                clutter_behaviour_get_n_actors      (ClutterBehaviour *behave);
ClutterActor*       clutter_behaviour_get_nth_actor     (ClutterBehaviour *behave,
                                                         gint index_);
ClutterAlpha*       clutter_behaviour_get_alpha         (ClutterBehaviour *behave);
void                clutter_behaviour_set_alpha         (ClutterBehaviour *behave,
                                                         ClutterAlpha *alpha);


Description

ClutterBehaviour is the base class for implementing behaviours. A behaviour is a controller object for ClutterActors; you can use a behaviour to control one or more properties of an actor (such as its opacity, or its position). A ClutterBehaviour is driven by an "alpha function" stored inside a ClutterAlpha object; an alpha function is a function depending solely on time. The alpha function computes a value which is then applied to the properties of the actors driven by a behaviour.

Clutter provides some pre-defined behaviours, like ClutterBehaviourPath, which controls the position of a set of actors making them "walk" along a set of nodes; ClutterBehaviourOpacity, which controls the opacity of a set of actors; ClutterBehaviourScale, which controls the width and height of a set of actors.

In order to implement a new behaviour you should subclass ClutterBehaviour and override the "alpha_notify" virtual function; inside the overridden function you should obtain the alpha value from the ClutterAlpha instance bound to the behaviour and apply it to the desiderd property (or properties) of every actor controlled by the behaviour.

Details

ClutterBehaviourClass

typedef struct {
  /* vfunc, not signal */
  void (*alpha_notify) (ClutterBehaviour *behave,
                        guint32           alpha_value);

  /* signals */
  void (*applied)  (ClutterBehaviour *behave,
		    ClutterActor     *actor);
  void (*removed)  (ClutterBehaviour *behave,
		    ClutterActor     *actor);
} ClutterBehaviourClass;

Base class for behaviours.

alpha_notify () virtual function, called each time the ClutterAlpha computes a new alpha value; the actors to which the behaviour applies should be changed in this function. Every subclass of ClutterBehaviour must implement this virtual function
applied () signal class handler for the ClutterBehaviour::applied signal
removed () signal class handler for the ClutterBehaviour::removed signal

Since 0.2


clutter_behaviour_apply ()

void                clutter_behaviour_apply             (ClutterBehaviour *behave,
                                                         ClutterActor *actor);

Applies behave to actor. This function adds a reference on the actor.

behave : a ClutterBehaviour
actor : a ClutterActor

Since 0.2


clutter_behaviour_remove ()

void                clutter_behaviour_remove            (ClutterBehaviour *behave,
                                                         ClutterActor *actor);

Removes actor from the list of ClutterActors to which behave applies. This function removes a reference on the actor.

behave : a ClutterBehaviour
actor : a ClutterActor

Since 0.2


clutter_behaviour_remove_all ()

void                clutter_behaviour_remove_all        (ClutterBehaviour *behave);

Removes every actor from the list that behave holds.

behave : a ClutterBehaviour

Since 0.4


clutter_behaviour_is_applied ()

gboolean            clutter_behaviour_is_applied        (ClutterBehaviour *behave,
                                                         ClutterActor *actor);

Check if behave applied to actor.

behave : a ClutterBehaviour
actor : a ClutterActor
Returns : TRUE if actor has behaviour. FALSE otherwise.

Since 0.4


ClutterBehaviourForeachFunc ()

void                (*ClutterBehaviourForeachFunc)      (ClutterBehaviour *behaviour,
                                                         ClutterActor *actor,
                                                         gpointer data);

This function is passed to clutter_behaviour_foreach_actor() and will be called for each actor driven by behaviour.

behaviour : the ClutterBehaviour
actor : an actor driven by behaviour
data : optional data passed to the function

Since 0.2


clutter_behaviour_actors_foreach ()

void                clutter_behaviour_actors_foreach    (ClutterBehaviour *behave,
                                                         ClutterBehaviourForeachFunc func,
                                                         gpointer data);

Calls func for every actor driven by behave.

behave : a ClutterBehaviour
func : a function called for each actor
data : optional data to be passed to the function, or NULL

Since 0.2


clutter_behaviour_get_actors ()

GSList*             clutter_behaviour_get_actors        (ClutterBehaviour *behave);

Retrieves all the actors to which behave applies. It is not recommended for derived classes to use this in there alpha notify method but use clutter_behaviour_actors_foreach as it avoids alot of needless allocations.

behave : a ClutterBehaviour
Returns : a list of actors. You should free the returned list with g_slist_free() when finished using it.

Since 0.2


clutter_behaviour_get_n_actors ()

gint                clutter_behaviour_get_n_actors      (ClutterBehaviour *behave);

Gets the number of actors this behaviour is applied too.

behave : a ClutterBehaviour
Returns : The number of applied actors

Since 0.2


clutter_behaviour_get_nth_actor ()

ClutterActor*       clutter_behaviour_get_nth_actor     (ClutterBehaviour *behave,
                                                         gint index_);

Gets an actor the behaviour was applied to referenced by index num.

behave : a ClutterBehaviour
index_ : the index of an actor this behaviour is applied too.
Returns : A Clutter actor or NULL if index_ is invalid.

Since 0.2


clutter_behaviour_get_alpha ()

ClutterAlpha*       clutter_behaviour_get_alpha         (ClutterBehaviour *behave);

Retrieves the ClutterAlpha object bound to behave.

behave : a ClutterBehaviour
Returns : a ClutterAlpha object, or NULL if no alpha object has been bound to this behaviour.

Since 0.2


clutter_behaviour_set_alpha ()

void                clutter_behaviour_set_alpha         (ClutterBehaviour *behave,
                                                         ClutterAlpha *alpha);

Binds alpha to a ClutterBehaviour. The ClutterAlpha object is what makes a behaviour work: for each tick of the timeline used by ClutterAlpha a new value of the alpha parameter is computed by the alpha function; the value should be used by the ClutterBehaviour to update one or more properties of the actors to which the behaviour applies.

behave : a ClutterBehaviour
alpha : a ClutterAlpha or NULL to unset a previously set alpha

Since 0.2