gstreamer/gst/gstelementfactory.c

671 lines
19 KiB
C

/* GStreamer
* Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
* 2000 Wim Taymans <wtay@chello.be>
* 2003 Benjamin Otte <in7y118@public.uni-hamburg.de>
*
* gstelementfactory.c: GstElementFactory object, support routines
*
* 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.
*/
/**
* SECTION:gstelementfactory
* @short_description: Create GstElements from a factory
* @see_also: #GstElement, #GstPlugin, #GstPluginFeature, #GstPadTemplate.
*
* #GstElementFactory is used to create instances of elements. A
* GstElementfactory can be added to a #GstPlugin as it is also a
* #GstPluginFeature.
*
* Use the gst_element_factory_find() and gst_element_factory_create()
* functions to create element instances or use gst_element_factory_make() as a
* convenient shortcut.
*
* The following code example shows you how to create a GstFileSrc element.
*
* <example>
* <title>Using an element factory</title>
* <programlisting language="c">
* #include &lt;gst/gst.h&gt;
*
* GstElement *src;
* GstElementFactory *srcfactory;
*
* gst_init (&amp;argc, &amp;argv);
*
* srcfactory = gst_element_factory_find ("filesrc");
* g_return_if_fail (srcfactory != NULL);
* src = gst_element_factory_create (srcfactory, "src");
* g_return_if_fail (src != NULL);
* ...
* </programlisting>
* </example>
*
* Last reviewed on 2005-11-23 (0.9.5)
*/
#include "gst_private.h"
#include "gstelement.h"
#include "gstelementdetails.h"
#include "gstinfo.h"
#include "gsturi.h"
#include "gstregistry.h"
#include "glib-compat-private.h"
GST_DEBUG_CATEGORY_STATIC (element_factory_debug);
#define GST_CAT_DEFAULT element_factory_debug
static void gst_element_factory_finalize (GObject * object);
static void gst_element_factory_cleanup (GstElementFactory * factory);
static GstPluginFeatureClass *parent_class = NULL;
/* static guint gst_element_factory_signals[LAST_SIGNAL] = { 0 }; */
/* this is defined in gstelement.c */
extern GQuark _gst_elementclass_factory;
#define _do_init \
{ \
GST_DEBUG_CATEGORY_INIT (element_factory_debug, "GST_ELEMENT_FACTORY", \
GST_DEBUG_BOLD | GST_DEBUG_FG_WHITE | GST_DEBUG_BG_RED, \
"element factories keep information about installed elements"); \
}
G_DEFINE_TYPE_WITH_CODE (GstElementFactory, gst_element_factory,
GST_TYPE_PLUGIN_FEATURE, _do_init);
static void
gst_element_factory_class_init (GstElementFactoryClass * klass)
{
GObjectClass *gobject_class = (GObjectClass *) klass;
parent_class = g_type_class_peek_parent (klass);
gobject_class->finalize = gst_element_factory_finalize;
}
static void
gst_element_factory_init (GstElementFactory * factory)
{
factory->staticpadtemplates = NULL;
factory->numpadtemplates = 0;
factory->uri_type = GST_URI_UNKNOWN;
factory->uri_protocols = NULL;
factory->interfaces = NULL;
}
static void
gst_element_factory_finalize (GObject * object)
{
GstElementFactory *factory = GST_ELEMENT_FACTORY (object);
gst_element_factory_cleanup (factory);
G_OBJECT_CLASS (parent_class)->finalize (object);
}
/**
* gst_element_factory_find:
* @name: name of factory to find
*
* Search for an element factory of the given name. Refs the returned
* element factory; caller is responsible for unreffing.
*
* Returns: #GstElementFactory if found, NULL otherwise
*/
GstElementFactory *
gst_element_factory_find (const gchar * name)
{
GstPluginFeature *feature;
g_return_val_if_fail (name != NULL, NULL);
feature = gst_registry_find_feature (gst_registry_get_default (), name,
GST_TYPE_ELEMENT_FACTORY);
if (feature)
return GST_ELEMENT_FACTORY (feature);
/* this isn't an error, for instance when you query if an element factory is
* present */
GST_LOG ("no such element factory \"%s\"", name);
return NULL;
}
static void
gst_element_factory_cleanup (GstElementFactory * factory)
{
GList *item;
__gst_element_details_clear (&factory->details);
if (factory->type) {
factory->type = G_TYPE_INVALID;
}
for (item = factory->staticpadtemplates; item; item = item->next) {
GstStaticPadTemplate *templ = item->data;
GstCaps *caps = (GstCaps *) & (templ->static_caps);
g_free ((gchar *) templ->static_caps.string);
/* FIXME: this is not threadsafe */
if (caps->refcount == 1) {
GstStructure *structure;
guint i;
for (i = 0; i < caps->structs->len; i++) {
structure = (GstStructure *) gst_caps_get_structure (caps, i);
gst_structure_set_parent_refcount (structure, NULL);
gst_structure_free (structure);
}
g_ptr_array_free (caps->structs, TRUE);
caps->refcount = 0;
}
g_slice_free (GstStaticPadTemplate, templ);
}
g_list_free (factory->staticpadtemplates);
factory->staticpadtemplates = NULL;
factory->numpadtemplates = 0;
factory->uri_type = GST_URI_UNKNOWN;
if (factory->uri_protocols) {
g_strfreev (factory->uri_protocols);
factory->uri_protocols = NULL;
}
g_list_foreach (factory->interfaces, (GFunc) g_free, NULL);
g_list_free (factory->interfaces);
factory->interfaces = NULL;
}
/**
* gst_element_register:
* @plugin: #GstPlugin to register the element with, or NULL for a static
* element (note that passing NULL only works in GStreamer 0.10.13 and later)
* @name: name of elements of this type
* @rank: rank of element (higher rank means more importance when autoplugging)
* @type: GType of element to register
*
* Create a new elementfactory capable of instantiating objects of the
* @type and add the factory to @plugin.
*
* Returns: TRUE, if the registering succeeded, FALSE on error
*/
gboolean
gst_element_register (GstPlugin * plugin, const gchar * name, guint rank,
GType type)
{
GstPluginFeature *existing_feature;
GstRegistry *registry;
GstElementFactory *factory;
GType *interfaces;
guint n_interfaces, i;
GstElementClass *klass;
GList *item;
g_return_val_if_fail (name != NULL, FALSE);
g_return_val_if_fail (g_type_is_a (type, GST_TYPE_ELEMENT), FALSE);
registry = gst_registry_get_default ();
/* check if feature already exists, if it exists there is no need to update it
* when the registry is getting updated, outdated plugins and all their
* features are removed and readded.
*/
existing_feature = gst_registry_lookup_feature (registry, name);
if (existing_feature) {
GST_DEBUG_OBJECT (registry, "update existing feature %p (%s)",
existing_feature, name);
factory = GST_ELEMENT_FACTORY_CAST (existing_feature);
factory->type = type;
existing_feature->loaded = TRUE;
g_type_set_qdata (type, _gst_elementclass_factory, factory);
gst_object_unref (existing_feature);
return TRUE;
}
factory =
GST_ELEMENT_FACTORY_CAST (g_object_newv (GST_TYPE_ELEMENT_FACTORY, 0,
NULL));
gst_plugin_feature_set_name (GST_PLUGIN_FEATURE_CAST (factory), name);
GST_LOG_OBJECT (factory, "Created new elementfactory for type %s",
g_type_name (type));
/* provide info needed during class structure setup */
g_type_set_qdata (type, _gst_elementclass_factory, factory);
klass = GST_ELEMENT_CLASS (g_type_class_ref (type));
if ((klass->details.longname == NULL) ||
(klass->details.klass == NULL) || (klass->details.author == NULL))
goto detailserror;
factory->type = type;
__gst_element_details_copy (&factory->details, &klass->details);
for (item = klass->padtemplates; item; item = item->next) {
GstPadTemplate *templ = item->data;
GstStaticPadTemplate *newt;
newt = g_slice_new (GstStaticPadTemplate);
newt->name_template = g_intern_string (templ->name_template);
newt->direction = templ->direction;
newt->presence = templ->presence;
newt->static_caps.caps.refcount = 0;
newt->static_caps.string = gst_caps_to_string (templ->caps);
factory->staticpadtemplates =
g_list_append (factory->staticpadtemplates, newt);
}
factory->numpadtemplates = klass->numpadtemplates;
/* special stuff for URI handling */
if (g_type_is_a (type, GST_TYPE_URI_HANDLER)) {
GstURIHandlerInterface *iface = (GstURIHandlerInterface *)
g_type_interface_peek (klass, GST_TYPE_URI_HANDLER);
if (!iface || (!iface->get_type && !iface->get_type_full) ||
(!iface->get_protocols && !iface->get_protocols_full))
goto urierror;
if (iface->get_type)
factory->uri_type = iface->get_type ();
else if (iface->get_type_full)
factory->uri_type = iface->get_type_full (factory->type);
if (!GST_URI_TYPE_IS_VALID (factory->uri_type))
goto urierror;
if (iface->get_protocols)
factory->uri_protocols = g_strdupv (iface->get_protocols ());
else if (iface->get_protocols_full)
factory->uri_protocols = iface->get_protocols_full (factory->type);
if (!factory->uri_protocols)
goto urierror;
}
interfaces = g_type_interfaces (type, &n_interfaces);
for (i = 0; i < n_interfaces; i++) {
__gst_element_factory_add_interface (factory, g_type_name (interfaces[i]));
}
g_free (interfaces);
if (plugin && plugin->desc.name) {
GST_PLUGIN_FEATURE_CAST (factory)->plugin_name = plugin->desc.name;
} else {
GST_PLUGIN_FEATURE_CAST (factory)->plugin_name = "NULL";
}
gst_plugin_feature_set_rank (GST_PLUGIN_FEATURE_CAST (factory), rank);
GST_PLUGIN_FEATURE_CAST (factory)->loaded = TRUE;
gst_registry_add_feature (registry, GST_PLUGIN_FEATURE_CAST (factory));
return TRUE;
/* ERRORS */
urierror:
{
GST_WARNING_OBJECT (factory, "error with uri handler!");
gst_element_factory_cleanup (factory);
return FALSE;
}
detailserror:
{
GST_WARNING_OBJECT (factory,
"The GstElementDetails don't seem to have been set properly");
gst_element_factory_cleanup (factory);
return FALSE;
}
}
/**
* gst_element_factory_create:
* @factory: factory to instantiate
* @name: name of new element
*
* Create a new element of the type defined by the given elementfactory.
* It will be given the name supplied, since all elements require a name as
* their first argument.
*
* Returns: new #GstElement or NULL if the element couldn't be created
*/
GstElement *
gst_element_factory_create (GstElementFactory * factory, const gchar * name)
{
GstElement *element;
GstElementClass *oclass;
GstElementFactory *newfactory;
g_return_val_if_fail (factory != NULL, NULL);
newfactory =
GST_ELEMENT_FACTORY (gst_plugin_feature_load (GST_PLUGIN_FEATURE
(factory)));
if (newfactory == NULL)
goto load_failed;
factory = newfactory;
if (name)
GST_INFO ("creating element \"%s\" named \"%s\"",
GST_PLUGIN_FEATURE_NAME (factory), GST_STR_NULL (name));
else
GST_INFO ("creating element \"%s\"", GST_PLUGIN_FEATURE_NAME (factory));
if (factory->type == 0)
goto no_type;
/* create an instance of the element, cast so we don't assert on NULL
* also set name as early as we can
*/
if (name)
element =
GST_ELEMENT_CAST (g_object_new (factory->type, "name", name, NULL));
else
element = GST_ELEMENT_CAST (g_object_newv (factory->type, 0, NULL));
if (G_UNLIKELY (element == NULL))
goto no_element;
/* fill in the pointer to the factory in the element class. The
* class will not be unreffed currently.
* Be thread safe as there might be 2 threads creating the first instance of
* an element at the same moment
*/
oclass = GST_ELEMENT_GET_CLASS (element);
if (!g_atomic_pointer_compare_and_exchange (
(gpointer) & oclass->elementfactory, NULL, factory))
gst_object_unref (factory);
GST_DEBUG ("created element \"%s\"", GST_PLUGIN_FEATURE_NAME (factory));
return element;
/* ERRORS */
load_failed:
{
GST_WARNING_OBJECT (factory,
"loading plugin containing feature %s returned NULL!", name);
return NULL;
}
no_type:
{
GST_WARNING_OBJECT (factory, "factory has no type");
gst_object_unref (factory);
return NULL;
}
no_element:
{
GST_WARNING_OBJECT (factory, "could not create element");
gst_object_unref (factory);
return NULL;
}
}
/**
* gst_element_factory_make:
* @factoryname: a named factory to instantiate
* @name: (allow-none): name of new element
*
* Create a new element of the type defined by the given element factory.
* If name is NULL, then the element will receive a guaranteed unique name,
* consisting of the element factory name and a number.
* If name is given, it will be given the name supplied.
*
* Returns: new #GstElement or NULL if unable to create element
*/
GstElement *
gst_element_factory_make (const gchar * factoryname, const gchar * name)
{
GstElementFactory *factory;
GstElement *element;
g_return_val_if_fail (factoryname != NULL, NULL);
GST_LOG ("gstelementfactory: make \"%s\" \"%s\"",
factoryname, GST_STR_NULL (name));
factory = gst_element_factory_find (factoryname);
if (factory == NULL)
goto no_factory;
GST_LOG_OBJECT (factory, "found factory %p", factory);
element = gst_element_factory_create (factory, name);
if (element == NULL)
goto create_failed;
gst_object_unref (factory);
return element;
/* ERRORS */
no_factory:
{
GST_INFO ("no such element factory \"%s\"!", factoryname);
return NULL;
}
create_failed:
{
GST_INFO_OBJECT (factory, "couldn't create instance!");
gst_object_unref (factory);
return NULL;
}
}
void
__gst_element_factory_add_static_pad_template (GstElementFactory * factory,
GstStaticPadTemplate * templ)
{
g_return_if_fail (factory != NULL);
g_return_if_fail (templ != NULL);
factory->staticpadtemplates =
g_list_append (factory->staticpadtemplates, templ);
factory->numpadtemplates++;
}
/**
* gst_element_factory_get_element_type:
* @factory: factory to get managed #GType from
*
* Get the #GType for elements managed by this factory. The type can
* only be retrieved if the element factory is loaded, which can be
* assured with gst_plugin_feature_load().
*
* Returns: the #GType for elements managed by this factory or 0 if
* the factory is not loaded.
*/
GType
gst_element_factory_get_element_type (GstElementFactory * factory)
{
g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), 0);
return factory->type;
}
/**
* gst_element_factory_get_longname:
* @factory: a #GstElementFactory
*
* Gets the longname for this factory
*
* Returns: the longname
*/
G_CONST_RETURN gchar *
gst_element_factory_get_longname (GstElementFactory * factory)
{
g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
return factory->details.longname;
}
/**
* gst_element_factory_get_klass:
* @factory: a #GstElementFactory
*
* Gets the class for this factory.
*
* Returns: the class
*/
G_CONST_RETURN gchar *
gst_element_factory_get_klass (GstElementFactory * factory)
{
g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
return factory->details.klass;
}
/**
* gst_element_factory_get_description:
* @factory: a #GstElementFactory
*
* Gets the description for this factory.
*
* Returns: the description
*/
G_CONST_RETURN gchar *
gst_element_factory_get_description (GstElementFactory * factory)
{
g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
return factory->details.description;
}
/**
* gst_element_factory_get_author:
* @factory: a #GstElementFactory
*
* Gets the author for this factory.
*
* Returns: the author
*/
G_CONST_RETURN gchar *
gst_element_factory_get_author (GstElementFactory * factory)
{
g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
return factory->details.author;
}
/**
* gst_element_factory_get_num_pad_templates:
* @factory: a #GstElementFactory
*
* Gets the number of pad_templates in this factory.
*
* Returns: the number of pad_templates
*/
guint
gst_element_factory_get_num_pad_templates (GstElementFactory * factory)
{
g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), 0);
return factory->numpadtemplates;
}
/**
* __gst_element_factory_add_interface:
* @elementfactory: The elementfactory to add the interface to
* @interfacename: Name of the interface
*
* Adds the given interfacename to the list of implemented interfaces of the
* element.
*/
void
__gst_element_factory_add_interface (GstElementFactory * elementfactory,
const gchar * interfacename)
{
g_return_if_fail (GST_IS_ELEMENT_FACTORY (elementfactory));
g_return_if_fail (interfacename != NULL);
g_return_if_fail (interfacename[0] != '\0'); /* no empty string */
elementfactory->interfaces =
g_list_prepend (elementfactory->interfaces, g_strdup (interfacename));
}
/**
* gst_element_factory_get_static_pad_templates:
* @factory: a #GstElementFactory
*
* Gets the #GList of #GstStaticPadTemplate for this factory.
*
* Returns: the padtemplates
*/
G_CONST_RETURN GList *
gst_element_factory_get_static_pad_templates (GstElementFactory * factory)
{
g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
return factory->staticpadtemplates;
}
/**
* gst_element_factory_get_uri_type:
* @factory: a #GstElementFactory
*
* Gets the type of URIs the element supports or #GST_URI_UNKNOWN if none.
*
* Returns: type of URIs this element supports
*/
gint
gst_element_factory_get_uri_type (GstElementFactory * factory)
{
g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), GST_URI_UNKNOWN);
return factory->uri_type;
}
/**
* gst_element_factory_get_uri_protocols:
* @factory: a #GstElementFactory
*
* Gets a NULL-terminated array of protocols this element supports or NULL if
* no protocols are supported. You may not change the contents of the returned
* array, as it is still owned by the element factory. Use g_strdupv() to
* make a copy of the protocol string array if you need to.
*
* Returns: the supported protocols or NULL
*/
gchar **
gst_element_factory_get_uri_protocols (GstElementFactory * factory)
{
g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), NULL);
return factory->uri_protocols;
}
/**
* gst_element_factory_has_interface:
* @factory: a #GstElementFactory
* @interfacename: an interface name
*
* Check if @factory implements the interface with name @interfacename.
*
* Returns: #TRUE when @factory implement the interface.
*
* Since: 0.10.14
*/
gboolean
gst_element_factory_has_interface (GstElementFactory * factory,
const gchar * interfacename)
{
GList *walk;
g_return_val_if_fail (GST_IS_ELEMENT_FACTORY (factory), FALSE);
for (walk = factory->interfaces; walk; walk = g_list_next (walk)) {
gchar *iname = (gchar *) walk->data;
if (!strcmp (iname, interfacename))
return TRUE;
}
return FALSE;
}