DOKK / manpages / debian 12 / libwayland-doc / wl_signal.3.en
wl_signal(3) Wayland wl_signal(3)

wl_signal - A source of a type of observable event.

#include <wayland-server-core.h>


void wl_signal_emit_mutable (struct wl_signal *signal, void *data)
static void wl_signal_init (struct wl_signal *signal)
static void wl_signal_add (struct wl_signal *signal, struct wl_listener *listener)
static struct wl_listener * wl_signal_get (struct wl_signal *signal, wl_notify_func_t notify)
static void wl_signal_emit (struct wl_signal *signal, void *data)


struct wl_list listener_list

A source of a type of observable event.

Signals are recognized points where significant events can be observed. Compositors as well as the server can provide signals. Observers are wl_listener's that are added through wl_signal_add. Signals are emitted using wl_signal_emit, which will invoke all listeners until that listener is removed by wl_list_remove() (or whenever the signal is destroyed).

See also

wl_listener for more information on using wl_signal

Add the specified listener to this signal.

Parameters

signal The signal that will emit events to the listener
listener The listener to add

Emits this signal, notifying all registered listeners.

Parameters

signal The signal object that will emit the signal
data The data that will be emitted with the signal

Emits this signal, notifying all registered listeners.

A safer version of wl_signal_emit() which can gracefully handle additions and deletions of any signal listener from within listener notification callbacks.

Listeners deleted during a signal emission and which have not already been notified at the time of deletion are not notified by that emission.

Listeners added (or readded) during signal emission are ignored by that emission.

Note that repurposing a listener without explicitly removing it and readding it is not supported and can lead to unexpected behavior.

Parameters

signal The signal object that will emit the signal
data The data that will be emitted with the signal

Since

1.20.90

Gets the listener struct for the specified callback.

Parameters

signal The signal that contains the specified listener
notify The listener that is the target of this search

Returns

the list item that corresponds to the specified listener, or NULL if none was found

Initialize a new wl_signal for use.

Parameters

signal The signal that will be initialized

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Fri Jul 8 2022 Version 1.21.0