Commit 5d76a2e9 authored by Ronald S. Bultje's avatar Ronald S. Bultje
Browse files

Implement generic interface stuff, with per-instance support checking instead of per-class checking

Original commit message from CVS:
Implement generic interface stuff, with per-instance support checking instead of per-class checking
parent 5a26d2f7
......@@ -144,13 +144,76 @@ gst_element_implements_interface (GstElement *element,
return FALSE;
}
Let's now add some functions so we can abuse this in case/check
functions.
GstInterface *
gst_interface_cast (gpointer from,
GType type)
{
GstInterface *iface;
/* check cast, give warning+fail if it's invalid */
if (!(iface = G_TYPE_CHECK_INSTANCE_CAST (G_OBJECT (element),
type, GstInterface))) {
return NULL;
}
/* if we're an element, take care that this interface
* is actually implemented */
if (GST_IS_ELEMENT (from)) {
gboolean interface_is_implemented =
gst_element_implements_interface (GST_ELEMENT (from),
type);
g_return_val_if_fail (interface_is_implemented == TRUE, NULL);
}
return iface;
}
gboolean
gst_interface_check (gpointer from,
GType type)
{
GstInterface *iface;
/* check cast, return FALSE if it fails, don't give a warning... */
if (!G_TYPE_CHECK_INSTANCE_CAST (from, type,
GstInterface)) {
return FALSE;
}
iface = G_TYPE_CHECK_INSTANCE_CAST (G_OBJECT (element),
type, GstInterface);
/* now, if we're an element (or derivative), is this thing
* actually implemented for real? */
if (GST_IS_ELEMENT (from)) {
if (!gst_element_implements_interface (GST_ELEMENT (from),
type)) {
return FALSE;
}
}
return TRUE;
}
#define GST_INTERFACE_CHECK_INSTANCE_CAST(obj, type, cast_t) \
((cast_t *) gst_interface_cast ((obj), (type))
#define GST_INTERFACE_CHECK_INSTANCE_TYPE(obj, type) \
(gst_interface_check ((obj), (type))
We could use this in the GST_IS_... () macros. For example, the
macro GST_IS_MIXER () would then look like this:
macros GST_IS_MIXER () and GST_MIXER () would then look like this:
/* Note that this is a non-standard macro, and with a reason! */
#define GST_MIXER(obj) \
(GST_INTERFACE_CHECK_INSTANCE_CAST ((obj), \
GST_TYPE_MIXER,
GstMixer))
#define GST_IS_MIXER(obj) \
(G_TYPE_CHECK_INSTANCE_TYPE ((obj), GST_TYPE_MIXER) && \
gst_element_implements_interface (GST_ELEMENT (obj), \
GST_TYPE_MIXER))
(GST_INTERFACE_CHECK_INSTANCE_TYPE ((obj), \
GST_TYPE_MIXER))
So the application would just tread it with the known macro, and
everything would look extremely simple to the end user.
......@@ -184,7 +247,8 @@ And alsa* would surely implement the same interface.
/* This is confusing naming... (i.e. FIXME)
* A channel is referred to both as the number of simultaneous
* sounds the input can handle as well as the in-/output itself
* sound streams the input can handle as well as the in-/output
* itself
*/
#define GST_MIXER_CHANNEL_INPUT (1<<0)
......
......@@ -107,6 +107,7 @@ libgstreamer_@GST_MAJORMINOR@_la_SOURCES = \
gstformat.c \
$(GST_INDEX_SRC) \
gstinfo.c \
gstinterface.c \
gstmemchunk.c \
gstpad.c \
gstpipeline.c \
......@@ -167,6 +168,7 @@ gst_headers = \
gstformat.h \
gstindex.h \
gstinfo.h \
gstinterface.h \
gstlog.h \
gstmacros.h \
gstmemchunk.h \
......
......@@ -55,6 +55,7 @@
#include <gst/gstevent.h>
#include <gst/gstclock.h>
#include <gst/gstsystemclock.h>
#include <gst/gstinterface.h>
#include <gst/gstparse.h>
#include <gst/gstregistry.h>
......
/* GStreamer
*
* Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
* 2000 Wim Taymans <wtay@chello.be>
*
* gstinterface.c: Interface functions
*
* 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., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "gstinterface.h"
#include "gstlog.h"
static void gst_interface_class_init (GstInterfaceClass *ifklass);
static gboolean gst_interface_supported_default (GstInterface *iface);
GType
gst_interface_get_type (void)
{
static GType gst_interface_type = 0;
if (!gst_interface_type) {
static const GTypeInfo gst_interface_info = {
sizeof (GstInterfaceClass),
(GBaseInitFunc) gst_interface_class_init,
NULL,
NULL,
NULL,
NULL,
0,
0,
NULL,
NULL
};
gst_interface_type = g_type_register_static (G_TYPE_INTERFACE,
"GstInterface",
&gst_interface_info, 0);
}
return gst_interface_type;
}
static void
gst_interface_class_init (GstInterfaceClass *klass)
{
klass->supported = gst_interface_supported_default;
}
static gboolean
gst_interface_supported_default (GstInterface *interface)
{
/* Well, if someone didn't set the virtual function,
* then something is clearly wrong. So big no-no here */
return FALSE;
}
/**
* gst_element_implements_interface:
* @element: #GstElement to check for the implementation of the interface
* @iface_type: (final) type of the interface which we want to be implemented
*
* Test whether the given element implements a certain interface of type
* iface_type, and test whether it is supported for this specific instance.
*/
gboolean
gst_element_implements_interface (GstElement *element,
GType iface_type)
{
if (G_TYPE_CHECK_INSTANCE_TYPE (G_OBJECT (element),
iface_type)) {
GstInterface *iface;
GstInterfaceClass *ifclass;
iface = G_TYPE_CHECK_INSTANCE_CAST (G_OBJECT (element),
iface_type, GstInterface);
ifclass = GST_INTERFACE_GET_CLASS (iface);
if (ifclass->supported != NULL &&
ifclass->supported (iface) == TRUE) {
return TRUE;
}
}
return FALSE;
}
/**
* gst_interface_cast:
* @from: the object (any sort) from which to cast to the interface
* @type: the interface type to cast to
*
* cast a given object to an interface type, and check whether this
* interface is supported for this specific instance.
*/
GstInterface *
gst_interface_cast (gpointer from,
GType iface_type)
{
GstInterface *iface;
/* check cast, give warning+fail if it's invalid */
if (!(iface = G_TYPE_CHECK_INSTANCE_CAST (from, iface_type,
GstInterface))) {
return NULL;
}
/* if we're an element, take care that this interface
* is actually implemented */
if (GST_IS_ELEMENT (from)) {
gboolean interface_is_implemented =
gst_element_implements_interface (GST_ELEMENT (from), iface_type);
g_return_val_if_fail (interface_is_implemented == TRUE, NULL);
}
return iface;
}
/**
* gst_interface_cast:
* @from: the object (any sort) from which to check from for the interface
* @type: the interface type to check for
*
* check a given object for an interface implementation, and check
* whether this interface is supported for this specific instance.
*/
gboolean
gst_interface_check (gpointer from,
GType type)
{
GstInterface *iface;
/* check cast, return FALSE if it fails, don't give a warning... */
if (!G_TYPE_CHECK_INSTANCE_CAST (from, type, GstInterface)) {
return FALSE;
}
iface = G_TYPE_CHECK_INSTANCE_CAST (from, type, GstInterface);
/* now, if we're an element (or derivative), is this thing
* actually implemented for real? */
if (GST_IS_ELEMENT (from)) {
if (!gst_element_implements_interface (GST_ELEMENT (from), type)) {
return FALSE;
}
}
return TRUE;
}
/* GStreamer
* Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
* 2000 Wim Taymans <wtay@chello.be>
*
* gstinterface.h: Declarations of interface stuff
*
* 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., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#ifndef __GST_INTERFACE_H__
#define __GST_INTERFACE_H__
#include <gst/gstelement.h>
G_BEGIN_DECLS
#define GST_TYPE_INTERFACE \
(gst_interface_get_type ())
#define GST_INTERFACE(obj) \
(GST_INTERFACE_CHECK_INSTANCE_CAST ((obj), GST_TYPE_INTERFACE, GstInterface))
#define GST_INTERFACE_CLASS(klass) \
(G_TYPE_CHECK_CLASS_CAST ((klass), GST_TYPE_INTERFACE, GstInterfaceClass))
#define GST_IS_INTERFACE(obj) \
(GST_INTERFACE_CHECK_INSTANCE_TYPE ((obj), GST_TYPE_INTERFACE))
#define GST_IS_INTERFACE_CLASS(klass) \
(G_TYPE_CHECK_CLASS_TYPE ((klass), GST_TYPE_INTERFACE))
#define GST_INTERFACE_GET_CLASS(inst) \
(G_TYPE_INSTANCE_GET_INTERFACE ((inst), GST_TYPE_INTERFACE, GstInterfaceClass))
typedef struct _GstInterface GstInterface;
/* This small extra virtual function is here to provide an
* interface functionality on a per-instance basis rather
* than a per-class basis, which is the case for glib.
*/
typedef struct _GstInterfaceClass {
GTypeInterface parent;
/* virtual functions */
gboolean (* supported) (GstInterface *iface);
} GstInterfaceClass;
#define GST_INTERFACE_CHECK_INSTANCE_CAST(obj, type, cast_t) \
((cast_t *) gst_interface_cast ((obj), (type)))
#define GST_INTERFACE_CHECK_INSTANCE_TYPE(obj, type) \
(gst_interface_check ((obj), (type)))
GType gst_interface_get_type (void);
/* wrapper functions to check for functionality implementation */
gboolean gst_element_implements_interface(GstElement *element,
GType iface_type);
GstInterface * gst_interface_cast (gpointer from,
GType type);
gboolean gst_interface_check (gpointer from,
GType type);
G_END_DECLS
#endif /* __GST_INTERFACE_H__ */
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