Creates a binding between source_property
on source
and target_property
on target
.
Whenever the source_property
is changed the target_property
is
updated using the same value. For instance:
g_object_bind_property (action, "active", widget, "sensitive", 0);
Will result in the "sensitive" property of the widget #GObject instance to be updated with the same value of the "active" property of the action #GObject instance.
If flags
contains %G_BINDING_BIDIRECTIONAL then the binding will be mutual:
if target_property
on target
changes then the source_property
on source
will be updated as well.
The binding will automatically be removed when either the source
or the
target
instances are finalized. To remove the binding without affecting the
source
and the target
you can just call g_object_unref() on the returned
#GBinding instance.
Removing the binding by calling g_object_unref() on it must only be done if
the binding, source
and target
are only used from a single thread and it
is clear that both source
and target
outlive the binding. Especially it
is not safe to rely on this if the binding, source
or target
can be
finalized from different threads. Keep another reference to the binding and
use g_binding_unbind() instead to be on the safe side.
A #GObject can have multiple bindings.
the property on source
to bind
the target #GObject
the property on target
to bind
flags to pass to #GBinding
Creates a binding between source_property
on source
and target_property
on target,
allowing you to set the transformation functions to be used by
the binding.
This function is the language bindings friendly version of g_object_bind_property_full(), using #GClosures instead of function pointers.
the property on source
to bind
the target #GObject
the property on target
to bind
flags to pass to #GBinding
a #GClosure wrapping the transformation function from the source
to the target,
or %NULL to use the default
a #GClosure wrapping the transformation function from the target
to the source,
or %NULL to use the default
This function is intended for #GObject implementations to re-enforce a [floating][floating-ref] object reference. Doing this is seldom required: all #GInitiallyUnowneds are created with a floating reference which usually just needs to be sunken by calling g_object_ref_sink().
Increases the freeze count on object
. If the freeze count is
non-zero, the emission of "notify" signals on object
is
stopped. The signals are queued until the freeze count is decreased
to zero. Duplicate notifications are squashed so that at most one
#GObject::notify signal is emitted for each property modified while the
object is frozen.
This is necessary for accessors that modify multiple properties to prevent premature notification while the object is still being modified.
Gets a named field from the objects table of associations (see g_object_set_data()).
name of the key for that association
Gets a property of an object.
The value
can be:
In general, a copy is made of the property contents and the caller is responsible for freeing the memory by calling g_value_unset().
Note that g_object_get_property() is really intended for language bindings, g_object_get() is much more convenient for C programming.
the name of the property to get
return location for the property value
This function gets back user data pointers stored via g_object_set_qdata().
A #GQuark, naming the user data pointer
Gets n_properties
properties for an object
.
Obtained properties will be set to values
. All properties must be valid.
Warnings will be emitted and undefined behaviour may result if invalid
properties are passed in.
the names of each property to get
the values of each property to get
Checks whether object
has a [floating][floating-ref] reference.
Emits a "notify" signal for the property property_name
on object
.
When possible, eg. when signaling a property change from within the class that registered the property, you should use g_object_notify_by_pspec() instead.
Note that emission of the notify signal may be blocked with g_object_freeze_notify(). In this case, the signal emissions are queued and will be emitted (in reverse order) when g_object_thaw_notify() is called.
the name of a property installed on the class of object
.
Emits a "notify" signal for the property specified by pspec
on object
.
This function omits the property name lookup, hence it is faster than g_object_notify().
One way to avoid using g_object_notify() from within the class that registered the properties, and using g_object_notify_by_pspec() instead, is to store the GParamSpec used with g_object_class_install_property() inside a static array, e.g.:
enum
{
PROP_0,
PROP_FOO,
PROP_LAST
};
static GParamSpec *properties[PROP_LAST];
static void
my_object_class_init (MyObjectClass *klass)
{
properties[PROP_FOO] = g_param_spec_int ("foo", "Foo", "The foo",
0, 100,
50,
G_PARAM_READWRITE);
g_object_class_install_property (gobject_class,
PROP_FOO,
properties[PROP_FOO]);
}
and then notify a change on the "foo" property with:
g_object_notify_by_pspec (self, properties[PROP_FOO]);
the #GParamSpec of a property installed on the class of object
.
Increase the reference count of object,
and possibly remove the
[floating][floating-ref] reference, if object
has a floating reference.
In other words, if the object is floating, then this call "assumes ownership" of the floating reference, converting it to a normal reference by clearing the floating flag while leaving the reference count unchanged. If the object is not floating, then this call adds a new normal reference increasing the reference count by one.
Since GLib 2.56, the type of object
will be propagated to the return type
under the same conditions as for g_object_ref().
Releases all references to other objects. This can be used to break reference cycles.
This function should only be called from object system implementations.
Sends the indicated command to the navigation interface.
The command to issue
Sends a mouse event to the navigation interface. Mouse event coordinates are sent relative to the display space of the related output area. This is usually the size in pixels of the window associated with the element implementing the #GstNavigation interface.
The type of mouse event, as a text string. Recognised values are "mouse-button-press", "mouse-button-release" and "mouse-move".
The button number of the button being pressed or released. Pass 0 for mouse-move events.
The x coordinate of the mouse event.
The y coordinate of the mouse event.
Sends a mouse scroll event to the navigation interface. Mouse event coordinates are sent relative to the display space of the related output area. This is usually the size in pixels of the window associated with the element implementing the #GstNavigation interface.
The x coordinate of the mouse event.
The y coordinate of the mouse event.
The delta_x coordinate of the mouse event.
The delta_y coordinate of the mouse event.
Each object carries around a table of associations from strings to pointers. This function lets you set an association.
If the object already had an association with that name, the old association will be destroyed.
Internally, the key
is converted to a #GQuark using g_quark_from_string().
This means a copy of key
is kept permanently (even after object
has been
finalized) — so it is recommended to only use a small, bounded set of values
for key
in your program, to avoid the #GQuark storage growing unbounded.
name of the key
data to associate with that key
Sets a property on an object.
the name of the property to set
the value
Remove a specified datum from the object's data associations, without invoking the association's destroy handler.
name of the key
This function gets back user data pointers stored via
g_object_set_qdata() and removes the data
from object
without invoking its destroy() function (if any was
set).
Usually, calling this function is only required to update
user data pointers with a destroy notifier, for example:
void
object_add_to_user_list (GObject *object,
const gchar *new_string)
{
// the quark, naming the object data
GQuark quark_string_list = g_quark_from_static_string ("my-string-list");
// retrieve the old string list
GList *list = g_object_steal_qdata (object, quark_string_list);
// prepend new string
list = g_list_prepend (list, g_strdup (new_string));
// this changed 'list', so we need to set it again
g_object_set_qdata_full (object, quark_string_list, list, free_string_list);
}
static void
free_string_list (gpointer data)
{
GList *node, *list = data;
for (node = list; node; node = node->next)
g_free (node->data);
g_list_free (list);
}
Using g_object_get_qdata() in the above example, instead of g_object_steal_qdata() would have left the destroy function set, and thus the partial string list would have been freed upon g_object_set_qdata_full().
A #GQuark, naming the user data pointer
Reverts the effect of a previous call to
g_object_freeze_notify(). The freeze count is decreased on object
and when it reaches zero, queued "notify" signals are emitted.
Duplicate notifications for each property are squashed so that at most one #GObject::notify signal is emitted for each property, in the reverse order in which they have been queued.
It is an error to call this function when the freeze count is zero.
Decreases the reference count of object
. When its reference count
drops to 0, the object is finalized (i.e. its memory is freed).
If the pointer to the #GObject may be reused in future (for example, if it is an instance variable of another object), it is recommended to clear the pointer to %NULL rather than retain a dangling pointer to a potentially invalid #GObject instance. Use g_clear_object() for this.
Emits a "notify" signal for the property property_name
on object
.
When possible, eg. when signaling a property change from within the class that registered the property, you should use g_object_notify_by_pspec() instead.
Note that emission of the notify signal may be blocked with g_object_freeze_notify(). In this case, the signal emissions are queued and will be emitted (in reverse order) when g_object_thaw_notify() is called.
This function essentially limits the life time of the closure
to
the life time of the object. That is, when the object is finalized,
the closure
is invalidated by calling g_closure_invalidate() on
it, in order to prevent invocations of the closure with a finalized
(nonexisting) object. Also, g_object_ref() and g_object_unref() are
added as marshal guards to the closure,
to ensure that an extra
reference count is held on object
during invocation of the
closure
. Usually, this function will be called on closures that
use this object
as closure data.
#GClosure to watch
Inspect a #GstEvent and return the #GstNavigationEventType of the event, or #GST_NAVIGATION_EVENT_INVALID if the event is not a #GstNavigation event.
Create a new navigation event given navigation command..
The navigation command to use.
Create a new navigation event for the given key press.
A string identifying the key press.
a bit-mask representing the state of the modifier keys (e.g. Control, Shift and Alt).
Create a new navigation event for the given key release.
A string identifying the released key.
a bit-mask representing the state of the modifier keys (e.g. Control, Shift and Alt).
Create a new navigation event for the given key mouse button press.
The number of the pressed mouse button.
The x coordinate of the mouse cursor.
The y coordinate of the mouse cursor.
a bit-mask representing the state of the modifier keys (e.g. Control, Shift and Alt).
Create a new navigation event for the given key mouse button release.
The number of the released mouse button.
The x coordinate of the mouse cursor.
The y coordinate of the mouse cursor.
a bit-mask representing the state of the modifier keys (e.g. Control, Shift and Alt).
Create a new navigation event for the new mouse location.
The x coordinate of the mouse cursor.
The y coordinate of the mouse cursor.
a bit-mask representing the state of the modifier keys (e.g. Control, Shift and Alt).
Create a new navigation event for the mouse scroll.
The x coordinate of the mouse cursor.
The y coordinate of the mouse cursor.
The x component of the scroll movement.
The y component of the scroll movement.
a bit-mask representing the state of the modifier keys (e.g. Control, Shift and Alt).
Create a new navigation event signalling that all currently active touch points are cancelled and should be discarded. For example, under Wayland this event might be sent when a swipe passes the threshold to be recognized as a gesture by the compositor.
a bit-mask representing the state of the modifier keys (e.g. Control, Shift and Alt).
Create a new navigation event for an added touch point.
A number uniquely identifying this touch point. It must stay unique to this touch point at least until an up event is sent for the same identifier, or all touch points are cancelled.
The x coordinate of the new touch point.
The y coordinate of the new touch point.
Pressure data of the touch point, from 0.0 to 1.0, or NaN if no data is available.
a bit-mask representing the state of the modifier keys (e.g. Control, Shift and Alt).
Create a new navigation event signalling the end of a touch frame. Touch frames signal that all previous down, motion and up events not followed by another touch frame event already should be considered simultaneous.
a bit-mask representing the state of the modifier keys (e.g. Control, Shift and Alt).
Create a new navigation event for a moved touch point.
A number uniquely identifying this touch point. It must correlate to exactly one previous touch_start event.
The x coordinate of the touch point.
The y coordinate of the touch point.
Pressure data of the touch point, from 0.0 to 1.0, or NaN if no data is available.
a bit-mask representing the state of the modifier keys (e.g. Control, Shift and Alt).
Create a new navigation event for a removed touch point.
A number uniquely identifying this touch point. It must correlate to exactly one previous down event, but can be reused after sending this event.
The x coordinate of the touch point.
The y coordinate of the touch point.
a bit-mask representing the state of the modifier keys (e.g. Control, Shift and Alt).
Inspect a #GstNavigation command event and retrieve the enum value of the associated command.
Retrieve the details of either a #GstNavigation mouse button press event or a mouse button release event. Determine which type the event is using gst_navigation_event_get_type() to retrieve the #GstNavigationEventType.
Find the #GParamSpec with the given name for an
interface. Generally, the interface vtable passed in as g_iface
will be the default vtable from g_type_default_interface_ref(), or,
if you know the interface has already been loaded,
g_type_default_interface_peek().
any interface vtable for the interface, or the default vtable for the interface
name of a property to look up.
Add a property to an interface; this is only useful for interfaces that are added to GObject-derived types. Adding a property to an interface forces all objects classes with that interface to have a compatible property. The compatible property could be a newly created #GParamSpec, but normally g_object_class_override_property() will be used so that the object class only needs to provide an implementation and inherits the property description, default value, bounds, and so forth from the interface property.
This function is meant to be called from the interface's default
vtable initialization function (the class_init
member of
#GTypeInfo.) It must not be called after after class_init
has
been called for any object types implementing this interface.
If pspec
is a floating reference, it will be consumed.
any interface vtable for the interface, or the default vtable for the interface.
the #GParamSpec for the new property
Lists the properties of an interface.Generally, the interface
vtable passed in as g_iface
will be the default vtable from
g_type_default_interface_ref(), or, if you know the interface has
already been loaded, g_type_default_interface_peek().
any interface vtable for the interface, or the default vtable for the interface
Check a bus message to see if it is a #GstNavigation event, and return the #GstNavigationMessageType identifying the type of the message if so.
Creates a new #GstNavigation message with type #GST_NAVIGATION_MESSAGE_ANGLES_CHANGED for notifying an application that the current angle, or current number of angles available in a multiangle video has changed.
A #GstObject to set as source of the new message.
The currently selected angle.
The number of viewing angles now available.
Creates a new instance of a #GObject subtype and sets its properties.
Construction parameters (see %G_PARAM_CONSTRUCT, %G_PARAM_CONSTRUCT_ONLY) which are not explicitly specified are set to their default values.
the type id of the #GObject subtype to instantiate
an array of #GParameter
Inspect a #GstQuery and return the #GstNavigationQueryType associated with it if it is a #GstNavigation query.
Parse the #GstNavigation command query and retrieve the nth
command from
it into cmd
. If the list contains less elements than nth,
cmd
will be
set to #GST_NAVIGATION_COMMAND_INVALID.
Set the #GstNavigation command query result fields in query
. The number
of commands passed must be equal to n_commands
.
a #GstQuery
An array containing n_cmds
GstNavigationCommand
values.
The Navigation interface is used for creating and injecting navigation related events such as mouse button presses, cursor motion and key presses. The associated library also provides methods for parsing received events, and for sending and receiving navigation related bus events. One main usecase is DVD menu navigation.
The main parts of the API are:
The GstNavigation interface, implemented by elements which provide an application with the ability to create and inject navigation events into the pipeline.
GstNavigation event handling API. GstNavigation events are created in response to calls on a GstNavigation interface implementation, and sent in the pipeline. Upstream elements can use the navigation event API functions to parse the contents of received messages.
GstNavigation message handling API. GstNavigation messages may be sent on the message bus to inform applications of navigation related changes in the pipeline, such as the mouse moving over a clickable region, or the set of available angles changing.
The GstNavigation message functions provide functions for creating and parsing custom bus messages for signaling GstNavigation changes.