2 * Copyright (C) 1999,2000 Erik Walthinsen <omega@cse.ogi.edu>
3 * 2000 Wim Taymans <wtay@chello.be>
5 * gstpadtemplate.c: Templates for pad creation
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Library General Public
9 * License as published by the Free Software Foundation; either
10 * version 2 of the License, or (at your option) any later version.
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Library General Public License for more details.
17 * You should have received a copy of the GNU Library General Public
18 * License along with this library; if not, write to the
19 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20 * Boston, MA 02111-1307, USA.
24 * SECTION:gstpadtemplate
25 * @short_description: Describe the media type of a pad.
26 * @see_also: #GstPad, #GstElementFactory
28 * Padtemplates describe the possible media types a pad or an elementfactory can
29 * handle. This allows for both inspection of handled types before loading the
30 * element plugin as well as identifying pads on elements that are not yet
31 * created (request or sometimes pads).
33 * Pad and PadTemplates have #GstCaps attached to it to describe the media type
34 * they are capable of dealing with. gst_pad_template_get_caps() or
35 * GST_PAD_TEMPLATE_CAPS() are used to get the caps of a padtemplate. It's not
36 * possible to modify the caps of a padtemplate after creation.
38 * PadTemplates have a #GstPadPresence property which identifies the lifetime
39 * of the pad and that can be retrieved with GST_PAD_TEMPLATE_PRESENCE(). Also
40 * the direction of the pad can be retrieved from the #GstPadTemplate with
41 * GST_PAD_TEMPLATE_DIRECTION().
43 * The GST_PAD_TEMPLATE_NAME_TEMPLATE () is important for GST_PAD_REQUEST pads
44 * because it has to be used as the name in the gst_element_get_request_pad()
45 * call to instantiate a pad from this template.
47 * Padtemplates can be created with gst_pad_template_new() or with
48 * gst_static_pad_template_get (), which creates a #GstPadTemplate from a
49 * #GstStaticPadTemplate that can be filled with the
50 * convenient GST_STATIC_PAD_TEMPLATE() macro.
52 * A padtemplate can be used to create a pad (see gst_pad_new_from_template()
53 * or gst_pad_new_from_static_template ()) or to add to an element class
54 * (see gst_element_class_add_pad_template ()).
56 * The following code example shows the code to create a pad from a padtemplate.
58 * <title>Create a pad from a padtemplate</title>
60 * GstStaticPadTemplate my_template =
61 * GST_STATIC_PAD_TEMPLATE (
62 * "sink", // the name of the pad
63 * GST_PAD_SINK, // the direction of the pad
64 * GST_PAD_ALWAYS, // when this pad will be present
65 * GST_STATIC_CAPS ( // the capabilities of the padtemplate
67 * "channels = (int) [ 1, 6 ]"
74 * pad = gst_pad_new_from_static_template (&my_template, "sink");
80 * The following example shows you how to add the padtemplate to an
81 * element class, this is usually done in the class_init of the class:
85 * my_element_class_init (GstMyElementClass *klass)
87 * GstElementClass *gstelement_class = GST_ELEMENT_CLASS (klass);
89 * gst_element_class_add_pad_template (gstelement_class,
90 * gst_static_pad_template_get (&my_template));
95 * Last reviewed on 2006-02-14 (0.10.3)
98 #include "gst_private.h"
101 #include "gstpadtemplate.h"
102 #include "gstenumtypes.h"
103 #include "gstutils.h"
105 #include "gsterror.h"
106 #include "gstvalue.h"
108 #define GST_CAT_DEFAULT GST_CAT_PADS
112 PROP_NAME_TEMPLATE = 1,
125 static guint gst_pad_template_signals[LAST_SIGNAL] = { 0 };
127 static void gst_pad_template_dispose (GObject * object);
128 static void gst_pad_template_set_property (GObject * object, guint prop_id,
129 const GValue * value, GParamSpec * pspec);
130 static void gst_pad_template_get_property (GObject * object, guint prop_id,
131 GValue * value, GParamSpec * pspec);
133 #define gst_pad_template_parent_class parent_class
134 G_DEFINE_TYPE (GstPadTemplate, gst_pad_template, GST_TYPE_OBJECT);
137 gst_pad_template_class_init (GstPadTemplateClass * klass)
139 GObjectClass *gobject_class;
140 GstObjectClass *gstobject_class;
142 gobject_class = (GObjectClass *) klass;
143 gstobject_class = (GstObjectClass *) klass;
146 * GstPadTemplate::pad-created:
147 * @pad_template: the object which received the signal.
148 * @pad: the pad that was created.
150 * This signal is fired when an element creates a pad from this template.
152 gst_pad_template_signals[TEMPL_PAD_CREATED] =
153 g_signal_new ("pad-created", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST,
154 G_STRUCT_OFFSET (GstPadTemplateClass, pad_created),
155 NULL, NULL, g_cclosure_marshal_generic, G_TYPE_NONE, 1, GST_TYPE_PAD);
157 gobject_class->dispose = gst_pad_template_dispose;
159 gobject_class->get_property = gst_pad_template_get_property;
160 gobject_class->set_property = gst_pad_template_set_property;
163 * GstPadTemplate:name-template
165 * The name template of the pad template.
169 g_object_class_install_property (gobject_class, PROP_NAME_TEMPLATE,
170 g_param_spec_string ("name-template", "Name template",
171 "The name template of the pad template", NULL,
172 G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS));
175 * GstPadTemplate:direction
177 * The direction of the pad described by the pad template.
181 g_object_class_install_property (gobject_class, PROP_DIRECTION,
182 g_param_spec_enum ("direction", "Direction",
183 "The direction of the pad described by the pad template",
184 GST_TYPE_PAD_DIRECTION, GST_PAD_UNKNOWN,
185 G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS));
188 * GstPadTemplate:presence
190 * When the pad described by the pad template will become available.
194 g_object_class_install_property (gobject_class, PROP_PRESENCE,
195 g_param_spec_enum ("presence", "Presence",
196 "When the pad described by the pad template will become available",
197 GST_TYPE_PAD_PRESENCE, GST_PAD_ALWAYS,
198 G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS));
201 * GstPadTemplate:caps
203 * The capabilities of the pad described by the pad template.
207 g_object_class_install_property (gobject_class, PROP_CAPS,
208 g_param_spec_boxed ("caps", "Caps",
209 "The capabilities of the pad described by the pad template",
211 G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS));
213 gstobject_class->path_string_separator = "*";
217 gst_pad_template_init (GstPadTemplate * templ)
222 gst_pad_template_dispose (GObject * object)
224 GstPadTemplate *templ = GST_PAD_TEMPLATE (object);
226 g_free (GST_PAD_TEMPLATE_NAME_TEMPLATE (templ));
227 if (GST_PAD_TEMPLATE_CAPS (templ)) {
228 gst_caps_unref (GST_PAD_TEMPLATE_CAPS (templ));
231 G_OBJECT_CLASS (parent_class)->dispose (object);
234 /* ALWAYS padtemplates cannot have conversion specifications (like src_%d),
235 * since it doesn't make sense.
236 * SOMETIMES padtemplates can do whatever they want, they are provided by the
238 * REQUEST padtemplates can be reverse-parsed (the user asks for 'sink1', the
239 * 'sink%d' template is automatically selected), so we need to restrict their
243 name_is_valid (const gchar * name, GstPadPresence presence)
247 if (presence == GST_PAD_ALWAYS) {
248 if (strchr (name, '%')) {
249 g_warning ("invalid name template %s: conversion specifications are not"
250 " allowed for GST_PAD_ALWAYS padtemplates", name);
253 } else if (presence == GST_PAD_REQUEST) {
254 if ((str = strchr (name, '%')) && strchr (str + 1, '%')) {
255 g_warning ("invalid name template %s: only one conversion specification"
256 " allowed in GST_PAD_REQUEST padtemplate", name);
259 if (str && (*(str + 1) != 's' && *(str + 1) != 'd' && *(str + 1) != 'u')) {
260 g_warning ("invalid name template %s: conversion specification must be of"
261 " type '%%d', '%%u' or '%%s' for GST_PAD_REQUEST padtemplate", name);
264 if (str && (*(str + 2) != '\0')) {
265 g_warning ("invalid name template %s: conversion specification must"
266 " appear at the end of the GST_PAD_REQUEST padtemplate name", name);
274 G_DEFINE_POINTER_TYPE (GstStaticPadTemplate, gst_static_pad_template);
277 * gst_static_pad_template_get:
278 * @pad_template: the static pad template
280 * Converts a #GstStaticPadTemplate into a #GstPadTemplate.
282 * Returns: (transfer full): a new #GstPadTemplate.
284 /* FIXME0.11: rename to gst_pad_template_new_from_static_pad_template() */
286 gst_static_pad_template_get (GstStaticPadTemplate * pad_template)
291 if (!name_is_valid (pad_template->name_template, pad_template->presence))
294 caps = gst_static_caps_get (&pad_template->static_caps);
296 new = g_object_new (gst_pad_template_get_type (),
297 "name", pad_template->name_template,
298 "name-template", pad_template->name_template,
299 "direction", pad_template->direction,
300 "presence", pad_template->presence, "caps", caps, NULL);
302 gst_caps_unref (caps);
308 * gst_pad_template_new:
309 * @name_template: the name template.
310 * @direction: the #GstPadDirection of the template.
311 * @presence: the #GstPadPresence of the pad.
312 * @caps: (transfer none): a #GstCaps set for the template.
314 * Creates a new pad template with a name according to the given template
315 * and with the given arguments.
317 * Returns: (transfer floating): a new #GstPadTemplate.
320 gst_pad_template_new (const gchar * name_template,
321 GstPadDirection direction, GstPadPresence presence, GstCaps * caps)
325 g_return_val_if_fail (name_template != NULL, NULL);
326 g_return_val_if_fail (caps != NULL, NULL);
327 g_return_val_if_fail (direction == GST_PAD_SRC
328 || direction == GST_PAD_SINK, NULL);
329 g_return_val_if_fail (presence == GST_PAD_ALWAYS
330 || presence == GST_PAD_SOMETIMES || presence == GST_PAD_REQUEST, NULL);
332 if (!name_is_valid (name_template, presence)) {
336 new = g_object_new (gst_pad_template_get_type (),
337 "name", name_template, "name-template", name_template,
338 "direction", direction, "presence", presence, "caps", caps, NULL);
344 * gst_static_pad_template_get_caps:
345 * @templ: a #GstStaticPadTemplate to get capabilities of.
347 * Gets the capabilities of the static pad template.
349 * Returns: (transfer full): the #GstCaps of the static pad template.
350 * Unref after usage. Since the core holds an additional
351 * ref to the returned caps, use gst_caps_make_writable()
352 * on the returned caps to modify it.
355 gst_static_pad_template_get_caps (GstStaticPadTemplate * templ)
357 g_return_val_if_fail (templ, NULL);
359 return gst_static_caps_get (&templ->static_caps);
363 * gst_pad_template_get_caps:
364 * @templ: a #GstPadTemplate to get capabilities of.
366 * Gets the capabilities of the pad template.
368 * Returns: (transfer full): the #GstCaps of the pad template.
372 gst_pad_template_get_caps (GstPadTemplate * templ)
375 g_return_val_if_fail (GST_IS_PAD_TEMPLATE (templ), NULL);
377 caps = GST_PAD_TEMPLATE_CAPS (templ);
379 return (caps ? gst_caps_ref (caps) : NULL);
383 * gst_pad_template_pad_created:
384 * @templ: a #GstPadTemplate that has been created
385 * @pad: the #GstPad that created it
387 * Emit the pad-created signal for this template when created by this pad.
390 gst_pad_template_pad_created (GstPadTemplate * templ, GstPad * pad)
392 g_signal_emit (templ, gst_pad_template_signals[TEMPL_PAD_CREATED], 0, pad);
396 gst_pad_template_set_property (GObject * object, guint prop_id,
397 const GValue * value, GParamSpec * pspec)
399 /* these properties are all construct-only */
401 case PROP_NAME_TEMPLATE:
402 GST_PAD_TEMPLATE_NAME_TEMPLATE (object) = g_value_dup_string (value);
405 GST_PAD_TEMPLATE_DIRECTION (object) =
406 (GstPadDirection) g_value_get_enum (value);
409 GST_PAD_TEMPLATE_PRESENCE (object) =
410 (GstPadPresence) g_value_get_enum (value);
413 GST_PAD_TEMPLATE_CAPS (object) = g_value_dup_boxed (value);
416 G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
422 gst_pad_template_get_property (GObject * object, guint prop_id, GValue * value,
425 /* these properties are all construct-only */
427 case PROP_NAME_TEMPLATE:
428 g_value_set_string (value, GST_PAD_TEMPLATE_NAME_TEMPLATE (object));
431 g_value_set_enum (value, GST_PAD_TEMPLATE_DIRECTION (object));
434 g_value_set_enum (value, GST_PAD_TEMPLATE_PRESENCE (object));
437 g_value_set_boxed (value, GST_PAD_TEMPLATE_CAPS (object));
440 G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);