GstChildProxy: GStreamer 1.0 Core Reference Manual

GstChildProxy

GstChildProxy — Interface for multi child elements.

Functions

guint	gst_child_proxy_get_children_count ()
GObject *	gst_child_proxy_get_child_by_name ()
GObject *	gst_child_proxy_get_child_by_index ()
gboolean	gst_child_proxy_lookup ()
void	gst_child_proxy_get_property ()
void	gst_child_proxy_get_valist ()
void	gst_child_proxy_get ()
void	gst_child_proxy_set_property ()
void	gst_child_proxy_set_valist ()
void	gst_child_proxy_set ()
void	gst_child_proxy_child_added ()
void	gst_child_proxy_child_removed ()

Signals

void	child-added	Run First
void	child-removed	Run First

Types and Values

	GstChildProxy
struct	GstChildProxyInterface

Object Hierarchy

    GInterface
    ╰── GstChildProxy

Prerequisites

GstChildProxy requires GObject.

Known Implementations

GstChildProxy is implemented by GstBin and GstPipeline.

Includes

#include <gst/gst.h>

Description

This interface abstracts handling of property sets for elements with children. Imagine elements such as mixers or polyphonic generators. They all have multiple GstPad or some kind of voice objects. Another use case are container elements like GstBin. The element implementing the interface acts as a parent for those child objects.

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" and "child2" implement the GstChildProxy interface.

Functions

gst_child_proxy_get_children_count ()

guint
gst_child_proxy_get_children_count (GstChildProxy *parent);

Gets the number of child objects this parent contains.

Parameters

parent

the parent object

Returns

the number of child objects

MT safe.

gst_child_proxy_get_child_by_name ()

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

Looks up a child element by the given name.

This virtual method has a default implementation that uses GstObject together with gst_object_get_name(). If the interface is to be used with GObjects, this methods needs to be overridden.

Parameters

parent	the parent object to get the child from
name	the child's name

Returns

the child object or NULL if not found. Unref after usage.

MT safe.

[transfer full][nullable]

gst_child_proxy_get_child_by_index ()

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

Fetches a child by its number.

Parameters

parent	the parent object to get the child from
index	the child's position in the child list

Returns

the child object or NULL if not found (index too high). Unref after usage.

MT safe.

[transfer full][nullable]

gst_child_proxy_lookup ()

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

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

MT safe.

Parameters

object	child proxy object to lookup the property in
name	name of the property to look up
target	pointer to a GObject that takes the real object to set property on.	[out][allow-none][transfer full]
pspec	pointer to take the GParamSpec describing the property.	[out][allow-none][transfer none]

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. For plain GObjects target is the same as object .

gst_child_proxy_get_property ()

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

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

Parameters

object	object to query
name	name of the property
value	a GValue that should take the result.	[out caller-allocates]

gst_child_proxy_get_valist ()

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

Gets properties of the parent object and its children.

Parameters

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 (GstChildProxy *object,
                     const gchar *first_property_name,
                     ...);

Gets properties of the parent object and its children.

Parameters

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 (GstChildProxy *object,
                              const gchar *name,
                              const GValue *value);

Sets a single property using the GstChildProxy mechanism.

Parameters

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 (GstChildProxy *object,
                            const gchar *first_property_name,
                            va_list var_args);

Sets properties of the parent object and its children.

Parameters

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 (GstChildProxy *object,
                     const gchar *first_property_name,
                     ...);

Sets properties of the parent object and its children.

Parameters

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 (GstChildProxy *parent,
                             GObject *child,
                             const gchar *name);

Emits the "child-added" signal.

Parameters

parent	the parent object
child	the newly added child
name	the name of the new child

gst_child_proxy_child_removed ()

void
gst_child_proxy_child_removed (GstChildProxy *parent,
                               GObject *child,
                               const gchar *name);

Emits the "child-removed" signal.

Parameters

parent	the parent object
child	the removed child
name	the name of the old child

Types and Values

GstChildProxy

typedef struct _GstChildProxy GstChildProxy;

Opaque GstChildProxy data structure.

struct GstChildProxyInterface

struct GstChildProxyInterface {
  GTypeInterface parent;

  /* methods */
  GObject * (*get_child_by_name)  (GstChildProxy * parent, const gchar * name);
  GObject * (*get_child_by_index) (GstChildProxy * parent, guint index);
  guint     (*get_children_count) (GstChildProxy * parent);
};

GstChildProxy interface.

Members

GTypeInterface `parent`;	parent interface type.
`get_child_by_name` ()	virtual method to fetch the child by name
`get_child_by_index` ()	virtual method to fetch the child by index
`get_children_count` ()	virtual method to get the children count

Signal Details

The `“child-added”` signal

void
user_function (GstChildProxy *child_proxy,
               GObject       *object,
               gchar         *name,
               gpointer       user_data)

Will be emitted after the object was added to the child_proxy .

Parameters

child_proxy	the GstChildProxy
object	the GObject that was added
name	the name of the new child
user_data	user data set when the signal handler was connected.

Flags: Run First

The `“child-removed”` signal

void
user_function (GstChildProxy *child_proxy,
               GObject       *object,
               gchar         *name,
               gpointer       user_data)

Will be emitted after the object was removed from the child_proxy .

Parameters

child_proxy	the GstChildProxy
object	the GObject that was removed
name	the name of the old child
user_data	user data set when the signal handler was connected.

Flags: Run First

GstChildProxy

Functions

Signals

Types and Values

Object Hierarchy

Prerequisites

Known Implementations

Includes

Description

Functions

gst_child_proxy_get_children_count ()

Parameters

Returns

gst_child_proxy_get_child_by_name ()

Parameters

Returns

gst_child_proxy_get_child_by_index ()

Parameters

Returns

gst_child_proxy_lookup ()

Parameters

Returns

gst_child_proxy_get_property ()

Parameters

gst_child_proxy_get_valist ()

Parameters

gst_child_proxy_get ()

Parameters

gst_child_proxy_set_property ()

Parameters

gst_child_proxy_set_valist ()

Parameters

gst_child_proxy_set ()

Parameters

gst_child_proxy_child_added ()

Parameters

gst_child_proxy_child_removed ()

Parameters

Types and Values

GstChildProxy

struct GstChildProxyInterface

Members

Signal Details

The “child-added” signal

Parameters

The “child-removed” signal

Parameters

See Also

The `“child-added”` signal

The `“child-removed”` signal