gstreamer/gst/gstbus.h
Mathieu Duponchelle 5df982fd10 docs: standardize GstBus documentation
* Don't mention explicitly that API is MT safe, this implies that
  other API is not. GStreamer API is assumed to be MT safe, thread
  safety should only be explicitly mentioned when API is *not* MT safe

* Don't repeat what annotations are stating with respect to ownership
  transfer, nullability

* Document virtual methods and the class structure

* Misc cleanup / typo fixes / addition of links

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/753>
2021-02-09 15:32:29 +01:00

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C

/* GStreamer
* Copyright (C) 2004 Wim Taymans <wim@fluendo.com>
*
* gstbus.h: Header for GstBus subsystem
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
* Boston, MA 02110-1301, USA.
*/
#ifndef __GST_BUS_H__
#define __GST_BUS_H__
typedef struct _GstBus GstBus;
typedef struct _GstBusPrivate GstBusPrivate;
typedef struct _GstBusClass GstBusClass;
#include <gst/gstmessage.h>
#include <gst/gstclock.h>
G_BEGIN_DECLS
/* --- standard type macros --- */
#define GST_TYPE_BUS (gst_bus_get_type ())
#define GST_BUS(bus) (G_TYPE_CHECK_INSTANCE_CAST ((bus), GST_TYPE_BUS, GstBus))
#define GST_IS_BUS(bus) (G_TYPE_CHECK_INSTANCE_TYPE ((bus), GST_TYPE_BUS))
#define GST_BUS_CLASS(bclass) (G_TYPE_CHECK_CLASS_CAST ((bclass), GST_TYPE_BUS, GstBusClass))
#define GST_IS_BUS_CLASS(bclass) (G_TYPE_CHECK_CLASS_TYPE ((bclass), GST_TYPE_BUS))
#define GST_BUS_GET_CLASS(bus) (G_TYPE_INSTANCE_GET_CLASS ((bus), GST_TYPE_BUS, GstBusClass))
#define GST_BUS_CAST(bus) ((GstBus*)(bus))
/**
* GstBusFlags:
* @GST_BUS_FLUSHING: The bus is currently dropping all messages
* @GST_BUS_FLAG_LAST: offset to define more flags
*
* The standard flags that a bus may have.
*/
typedef enum {
GST_BUS_FLUSHING = (GST_OBJECT_FLAG_LAST << 0),
/* padding */
GST_BUS_FLAG_LAST = (GST_OBJECT_FLAG_LAST << 1)
} GstBusFlags;
/**
* GstBusSyncReply:
* @GST_BUS_DROP: drop the message
* @GST_BUS_PASS: pass the message to the async queue
* @GST_BUS_ASYNC: pass message to async queue, continue if message is handled
*
* The result values for a GstBusSyncHandler.
*/
typedef enum
{
GST_BUS_DROP = 0,
GST_BUS_PASS = 1,
GST_BUS_ASYNC = 2
} GstBusSyncReply;
/**
* GstBusSyncHandler:
* @bus: the #GstBus that sent the message
* @message: the #GstMessage
* @user_data: user data that has been given, when registering the handler
*
* Handler will be invoked synchronously, when a new message has been injected
* into the bus. This function is mostly used internally. Only one sync handler
* can be attached to a given bus.
*
* If the handler returns %GST_BUS_DROP, it should unref the message, else the
* message should not be unreffed by the sync handler.
*
* Returns: #GstBusSyncReply stating what to do with the message
*/
typedef GstBusSyncReply (*GstBusSyncHandler) (GstBus * bus, GstMessage * message, gpointer user_data);
/**
* GstBusFunc:
* @bus: the #GstBus that sent the message
* @message: the #GstMessage
* @user_data: user data that has been given, when registering the handler
*
* Specifies the type of function passed to gst_bus_add_watch() or
* gst_bus_add_watch_full(), which is called from the mainloop when a message
* is available on the bus.
*
* The message passed to the function will be unreffed after execution of this
* function so it should not be freed in the function.
*
* Note that this function is used as a #GSourceFunc which means that returning
* %FALSE will remove the #GSource from the mainloop.
*
* Returns: %FALSE if the event source should be removed.
*/
typedef gboolean (*GstBusFunc) (GstBus * bus, GstMessage * message, gpointer user_data);
/**
* GstBus:
* @object: the parent structure
*
* The opaque #GstBus data structure.
*/
struct _GstBus
{
GstObject object;
/*< private >*/
GstBusPrivate *priv;
gpointer _gst_reserved[GST_PADDING];
};
/**
* GstBusClass:
* @parent_class: the parent class structure
*
* GStreamer bus class.
*/
struct _GstBusClass
{
GstObjectClass parent_class;
/* signals */
/**
* GstBusClass::message:
* @bus: the #GstBus
* @message: the message that has been posted asynchronously
*
* A message has been posted on the bus.
*/
void (*message) (GstBus *bus, GstMessage *message);
/**
* GstBusClass::sync_message:
* @bus: the #GstBus
* @message: the message that has been posted synchronously
*
* A message has been posted on the bus.
*/
void (*sync_message) (GstBus *bus, GstMessage *message);
/*< private >*/
gpointer _gst_reserved[GST_PADDING];
};
GST_API
GType gst_bus_get_type (void);
GST_API
GstBus* gst_bus_new (void);
GST_API
gboolean gst_bus_post (GstBus * bus, GstMessage * message);
GST_API
gboolean gst_bus_have_pending (GstBus * bus);
GST_API
GstMessage * gst_bus_peek (GstBus * bus);
GST_API
GstMessage * gst_bus_pop (GstBus * bus);
GST_API
GstMessage * gst_bus_pop_filtered (GstBus * bus, GstMessageType types);
GST_API
GstMessage * gst_bus_timed_pop (GstBus * bus, GstClockTime timeout);
GST_API
GstMessage * gst_bus_timed_pop_filtered (GstBus * bus, GstClockTime timeout, GstMessageType types);
GST_API
void gst_bus_set_flushing (GstBus * bus, gboolean flushing);
/* synchronous dispatching */
GST_API
void gst_bus_set_sync_handler (GstBus * bus, GstBusSyncHandler func,
gpointer user_data, GDestroyNotify notify);
/* asynchronous message notifications */
GST_API
void gst_bus_get_pollfd (GstBus * bus, GPollFD *fd);
/* GSource based dispatching */
GST_API
GSource * gst_bus_create_watch (GstBus * bus);
GST_API
guint gst_bus_add_watch_full (GstBus * bus,
gint priority,
GstBusFunc func,
gpointer user_data,
GDestroyNotify notify);
GST_API
guint gst_bus_add_watch (GstBus * bus,
GstBusFunc func,
gpointer user_data);
GST_API
gboolean gst_bus_remove_watch (GstBus * bus);
/* polling the bus */
GST_API
GstMessage* gst_bus_poll (GstBus *bus, GstMessageType events,
GstClockTime timeout);
/* signal based dispatching helper functions. */
GST_API
gboolean gst_bus_async_signal_func (GstBus *bus, GstMessage *message,
gpointer data);
GST_API
GstBusSyncReply gst_bus_sync_signal_handler (GstBus *bus, GstMessage *message,
gpointer data);
/* convenience api to add/remove a gsource that emits the async signals */
GST_API
void gst_bus_add_signal_watch (GstBus * bus);
GST_API
void gst_bus_add_signal_watch_full (GstBus * bus, gint priority);
GST_API
void gst_bus_remove_signal_watch (GstBus * bus);
GST_API
void gst_bus_enable_sync_message_emission (GstBus * bus);
GST_API
void gst_bus_disable_sync_message_emission (GstBus * bus);
G_DEFINE_AUTOPTR_CLEANUP_FUNC(GstBus, gst_object_unref)
G_END_DECLS
#endif /* __GST_BUS_H__ */