GstChildProxy

GstChildProxy — Interface for multi child elements.

Synopsis


#include <gst/gst.h>


                    GstChildProxy;
                    GstChildProxyInterface;
guint               gst_child_proxy_get_children_count  (GstChildProxy *parent);
GstObject*          gst_child_proxy_get_child_by_name   (GstChildProxy *parent,
                                                         const gchar *name);
GstObject*          gst_child_proxy_get_child_by_index  (GstChildProxy *parent,
                                                         guint index);
gboolean            gst_child_proxy_lookup              (GstObject *object,
                                                         const gchar *name,
                                                         GstObject **target,
                                                         GParamSpec **pspec);
void                gst_child_proxy_get_property        (GstObject *object,
                                                         const gchar *name,
                                                         GValue *value);
void                gst_child_proxy_get_valist          (GstObject *object,
                                                         const gchar *first_property_name,
                                                         va_list var_args);
void                gst_child_proxy_get                 (GstObject *object,
                                                         const gchar *first_property_name,
                                                         ...);
void                gst_child_proxy_set_property        (GstObject *object,
                                                         const gchar *name,
                                                         const GValue *value);
void                gst_child_proxy_set_valist          (GstObject *object,
                                                         const gchar *first_property_name,
                                                         va_list var_args);
void                gst_child_proxy_set                 (GstObject *object,
                                                         const gchar *first_property_name,
                                                         ...);
void                gst_child_proxy_child_added         (GstObject *object,
                                                         GstObject *child);
void                gst_child_proxy_child_removed       (GstObject *object,
                                                         GstObject *child);


Object Hierarchy


  GInterface
   +----GstChildProxy

Prerequisites

GstChildProxy requires GstObject.

Known Implementations

GstChildProxy is implemented by GstPipeline and GstBin.

Description

This interface abstracts handling of property sets for child elements. Imagine elements such as mixers or polyphonic generators. They all have multiple GstPad or some kind of voice objects. The element acts as a parent for those child objects. Each child has the same properties.

By implementing this interface the child properties can be accessed from the parent element by using gst_child_proxy_get() and gst_child_proxy_set().

Property names are written as "child-name::property-name". The whole naming scheme is recursive. Thus "child1::child2::property" is valid too, if "child1" also implements the GstChildProxy interface.

Details

GstChildProxy

typedef struct _GstChildProxy GstChildProxy;

Opaque GstChildProxy data structure.


GstChildProxyInterface

typedef struct {
  GTypeInterface parent;

  /* methods */
  GstObject *(*get_child_by_index) (GstChildProxy * parent, guint index);
  guint (*get_children_count) (GstChildProxy * parent);
} GstChildProxyInterface;

GstChildProxyInterface interface.

GTypeInterface parent; parent interface type.
get_child_by_index () virtual method to fetch the child
get_children_count () virtual method to get the children count

gst_child_proxy_get_children_count ()

guint               gst_child_proxy_get_children_count  (GstChildProxy *parent);

Gets the number of child objects this parent contains.

parent : the parent object
Returns : the number of child objects MT safe.

gst_child_proxy_get_child_by_name ()

GstObject*          gst_child_proxy_get_child_by_name   (GstChildProxy *parent,
                                                         const gchar *name);

Looks up a child element by the given name.

Implementors can use GstObject together with gst_object_get_name()

parent : the parent object to get the child from
name : the childs name
Returns : the child object or NULL if not found. Unref after usage. MT safe.

gst_child_proxy_get_child_by_index ()

GstObject*          gst_child_proxy_get_child_by_index  (GstChildProxy *parent,
                                                         guint index);

Fetches a child by its number.

parent : the parent object to get the child from
index : the childs position in the child list
Returns : the child object or NULL if not found (index too high). Unref after usage. MT safe.

gst_child_proxy_lookup ()

gboolean            gst_child_proxy_lookup              (GstObject *object,
                                                         const gchar *name,
                                                         GstObject **target,
                                                         GParamSpec **pspec);

Looks up which object and GParamSpec would be effected by the given name.

object : object to lookup the property in
name : name of the property to look up
target : pointer to a GstObject that takes the real object to set property on
pspec : pointer to take the GParamSpec describing the property
Returns : TRUE if target and pspec could be found. FALSE otherwise. In that case the values for pspec and target are not modified. Unref target after usage. MT safe.

gst_child_proxy_get_property ()

void                gst_child_proxy_get_property        (GstObject *object,
                                                         const gchar *name,
                                                         GValue *value);

Gets a single property using the GstChildProxy mechanism. You are responsible for for freeing it by calling g_value_unset()

object : object to query
name : name of the property
value : a GValue that should take the result.

gst_child_proxy_get_valist ()

void                gst_child_proxy_get_valist          (GstObject *object,
                                                         const gchar *first_property_name,
                                                         va_list var_args);

Gets properties of the parent object and its children.

object : the object to query
first_property_name : name of the first property to get
var_args : return location for the first property, followed optionally by more name/return location pairs, followed by NULL

gst_child_proxy_get ()

void                gst_child_proxy_get                 (GstObject *object,
                                                         const gchar *first_property_name,
                                                         ...);

Gets properties of the parent object and its children.

object : the parent object
first_property_name : name of the first property to get
... : return location for the first property, followed optionally by more name/return location pairs, followed by NULL

gst_child_proxy_set_property ()

void                gst_child_proxy_set_property        (GstObject *object,
                                                         const gchar *name,
                                                         const GValue *value);

Sets a single property using the GstChildProxy mechanism.

object : the parent object
name : name of the property to set
value : new GValue for the property

gst_child_proxy_set_valist ()

void                gst_child_proxy_set_valist          (GstObject *object,
                                                         const gchar *first_property_name,
                                                         va_list var_args);

Sets properties of the parent object and its children.

object : the parent object
first_property_name : name of the first property to set
var_args : value for the first property, followed optionally by more name/value pairs, followed by NULL

gst_child_proxy_set ()

void                gst_child_proxy_set                 (GstObject *object,
                                                         const gchar *first_property_name,
                                                         ...);

Sets properties of the parent object and its children.

object : the parent object
first_property_name : name of the first property to set
... : value for the first property, followed optionally by more name/value pairs, followed by NULL

gst_child_proxy_child_added ()

void                gst_child_proxy_child_added         (GstObject *object,
                                                         GstObject *child);

Emits the "child-added" signal.

object : the parent object
child : the newly added child

gst_child_proxy_child_removed ()

void                gst_child_proxy_child_removed       (GstObject *object,
                                                         GstObject *child);

Emits the "child-removed" signal.

object : the parent object
child : the newly added child

See Also

GstBin