element: add convenience macros to register

Define separate macros to define an element
apart from the plugin itself.
These macros will help to register
elements a part from a plugin.
By example in the case of a gstreamer static build
producing the libgstreamer-full library.

More details here:

https://gitlab.freedesktop.org/gstreamer/gst-build/-/merge_requests/199

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/661>
This commit is contained in:
Julian Bouzas 2020-08-31 14:05:49 -04:00 committed by Stéphane Cerveau
parent 80f671207a
commit 7828237496

View file

@ -28,6 +28,150 @@
G_BEGIN_DECLS
/**
* _GST_ELEMENT_REGISTER_DEFINE_BEGIN: (attributes doc.skip=true)
*/
#define _GST_ELEMENT_REGISTER_DEFINE_BEGIN(element) \
G_BEGIN_DECLS \
gboolean G_PASTE (gst_element_register_, element) (GstPlugin * plugin) \
{ \
gboolean ret = FALSE; \
{\
G_END_DECLS
/**
* _GST_ELEMENT_REGISTER_DEFINE_END: (attributes doc.skip=true)
*/
#define _GST_ELEMENT_REGISTER_DEFINE_END(element_name, rank, type) \
G_BEGIN_DECLS \
} \
ret |= gst_element_register (plugin, element_name, rank, type); \
return ret; \
} \
G_END_DECLS
/**
* GST_ELEMENT_REGISTER_DEFINE_CUSTOM:
*
* @element: The element name in lower case, with words separated by '_'.
* Used to generate `gst_element_register_*(GstPlugin* plugin)`.
* @register_func: pointer to a method with the format: `gboolean register_func (GstPlugin* plugin);`
*
* A convenience macro to define the entry point of an
* element `gst_element_register_*(GstPlugin* plugin)` which uses
* register_func as the main registration method for the element.
* As an example, you may define the element named "streamer-filter"
* with the namespace `my` as following using `element_register_custom`:
*
* ```
* GST_ELEMENT_REGISTER_DEFINE_CUSTOM (my_element, element_register_custom)
* ```
*
* Since: 1.20
*/
#define GST_ELEMENT_REGISTER_DEFINE_CUSTOM(element, register_func) \
G_BEGIN_DECLS \
gboolean G_PASTE (gst_element_register_, element) (GstPlugin * plugin) \
{ \
return register_func (plugin); \
} \
G_END_DECLS
/**
* GST_ELEMENT_REGISTER_DEFINE:
*
* @e: The element name in lower case, with words separated by '_'.
* Used to generate `gst_element_register_*(GstPlugin* plugin)`.
* @e_n: The public name of the element
* @r: The #GstRank of the element (higher rank means more importance when autoplugging, see #GstRank)
* @t: The #GType of the element.
*
* A convenience macro to define the entry point of an
* element `gst_element_register_*(GstPlugin* plugin)`.
* As an example, you may define the element named "streamer-filter"
* with the namespace `my` as following:
*
* ```
* GST_ELEMENT_REGISTER_REGISTER_DEFINE (stream_filter, "stream-filter", GST_RANK_PRIMARY, MY_TYPE_STREAM_FILTER)
* ```
*
* Since: 1.20
*/
#define GST_ELEMENT_REGISTER_DEFINE(e, e_n, r, t) _GST_ELEMENT_REGISTER_DEFINE_BEGIN(e) _GST_ELEMENT_REGISTER_DEFINE_END(e_n, r, t)
/**
* GST_ELEMENT_REGISTER_DEFINE_WITH_CODE:
*
* @e: The element name in lower case, with words separated by '_'.
* Used to generate `gst_element_register_*(GstPlugin* plugin)`.
* @e_n: The public name of the element
* @r: The #GstRank of the element (higher rank means more importance when autoplugging, see #GstRank)
* @t: The #GType of the element.
* @_c_: Custom code that gets inserted in the gst_element_register_*() function.
*
* A convenience macro to define the entry point of an
* element `gst_element_register_*(GstPlugin* plugin)` executing code
* before gst_element_register in `gst_element_register_*(GstPlugin* plugin)`.
* As an example, you may define the element named "stream-filter"
* with the namespace `my` as following:
*
* ```
* #define _pre_register_init \
* ret |= my_stream_filter_pre_register (plugin);
* GST_ELEMENT_REGISTER_DEFINE_WITH_CODE (stream_filter, "stream-filter", GST_RANK_PRIMARY, MY_TYPE_STREAM_FILTER, _pre_register_init)
* ```
*
* Since: 1.20
*/
#define GST_ELEMENT_REGISTER_DEFINE_WITH_CODE(e, e_n, r, t, _c_) _GST_ELEMENT_REGISTER_DEFINE_BEGIN(e) {_c_;} _GST_ELEMENT_REGISTER_DEFINE_END(e_n, r, t)
/**
* GST_ELEMENT_REGISTER_DECLARE:
* @element: The element name in lower case, with words separated by '_'.
*
* This macro can be used to declare a new element.
* It has to be used in combination with #GST_ELEMENT_REGISTER_DEFINE macros
* and must be placed outside any block to declare the element registration
* function.
* As an example, you may declare the element named "stream-filter"
* with the namespace `my` as following:
*
* ```
* GST_ELEMENT_REGISTER_DECLARE (stream_filter)
* ```
*
* Since: 1.20
*/
#define GST_ELEMENT_REGISTER_DECLARE(element) \
G_BEGIN_DECLS \
gboolean G_PASTE(gst_element_register_, element) (GstPlugin * plugin) \
G_END_DECLS
/**
* GST_ELEMENT_REGISTER:
* @element: The element name in lower case, with words separated by '_'.
* @plugin: The #GstPlugin where to register the element.
*
* This macro can be used to register an element into a #GstPlugin.
* This method will be usually called in the plugin init function
* but can also be called with a NULL plugin,
* for example with a static registration of the element.
* It has to be used in combination with #GST_ELEMENT_REGISTER_DECLARE.
*
* ```
* GstPlugin* plugin;
*
* ...
*
* GST_ELEMENT_REGISTER (stream_filter, plugin);
* ```
*
* Since: 1.20
*/
#define GST_ELEMENT_REGISTER(element, plugin) G_PASTE(gst_element_register_, element) (plugin)
/* gstelement.h and gstelementfactory.h include each other */
typedef struct _GstElement GstElement;
typedef struct _GstElementClass GstElementClass;