File: gstchildproxy.c

package info (click to toggle)
gstreamer1.0 1.4.4-2%2Bdeb8u1
  • links: PTS
  • area: main
  • in suites: jessie
  • size: 30,228 kB
  • ctags: 22,496
  • sloc: ansic: 137,307; xml: 18,193; sh: 12,851; makefile: 2,105; perl: 1,537; yacc: 865; python: 433; lex: 164; lisp: 154; cpp: 38; sed: 16
file content (565 lines) | stat: -rw-r--r-- 15,514 bytes parent folder | download | duplicates (3)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
/* GStreamer
 * Copyright (C) 2005 Stefan Kost <ensonic@users.sf.net>
 *
 * gstchildproxy.c: interface for multi child elements
 *
 * 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.
 */

/**
 * SECTION:gstchildproxy
 * @short_description: Interface for multi child elements.
 * @see_also: #GstBin
 *
 * This interface abstracts handling of property sets for elements with
 * children. Imagine elements such as mixers or polyphonic generators. They all
 * have multiple #GstPad or some kind of voice objects. Another use case are
 * container elements like #GstBin.
 * The element implementing the interface acts as a parent for those child
 * objects.
 *
 * By implementing this interface the child properties can be accessed from the
 * parent element by using gst_child_proxy_get() and gst_child_proxy_set().
 *
 * Property names are written as "child-name::property-name". The whole naming
 * scheme is recursive. Thus "child1::child2::property" is valid too, if
 * "child1" and "child2" implement the #GstChildProxy interface.
 */

#include "gst_private.h"

#include "gstchildproxy.h"
#include <gobject/gvaluecollector.h>

/* signals */
enum
{
  CHILD_ADDED,
  CHILD_REMOVED,
  LAST_SIGNAL
};

static guint signals[LAST_SIGNAL] = { 0 };

static GObject *
gst_child_proxy_default_get_child_by_name (GstChildProxy * parent,
    const gchar * name)
{
  guint count, i;
  GObject *object, *result;
  gchar *object_name;

  g_return_val_if_fail (GST_IS_CHILD_PROXY (parent), NULL);
  g_return_val_if_fail (name != NULL, NULL);

  result = NULL;

  count = gst_child_proxy_get_children_count (parent);
  for (i = 0; i < count; i++) {
    gboolean eq;

    if (!(object = gst_child_proxy_get_child_by_index (parent, i)))
      continue;

    if (!GST_IS_OBJECT (object)) {
      goto next;
    }
    object_name = gst_object_get_name (GST_OBJECT_CAST (object));
    if (object_name == NULL) {
      g_warning ("child %u of parent %s has no name", i,
          GST_OBJECT_NAME (parent));
      goto next;
    }
    eq = g_str_equal (object_name, name);
    g_free (object_name);

    if (eq) {
      result = object;
      break;
    }
  next:
    g_object_unref (object);
  }
  return result;
}


/**
 * gst_child_proxy_get_child_by_name:
 * @parent: the parent object to get the child from
 * @name: the child's name
 *
 * Looks up a child element by the given name.
 *
 * This virtual method has a default implementation that uses #GstObject
 * together with gst_object_get_name(). If the interface is to be used with
 * #GObjects, this methods needs to be overridden.
 *
 * Returns: (transfer full) (nullable): the child object or %NULL if
 *     not found. Unref after usage.
 *
 * MT safe.
 */
GObject *
gst_child_proxy_get_child_by_name (GstChildProxy * parent, const gchar * name)
{
  g_return_val_if_fail (GST_IS_CHILD_PROXY (parent), 0);

  return (GST_CHILD_PROXY_GET_INTERFACE (parent)->get_child_by_name (parent,
          name));
}

/**
 * gst_child_proxy_get_child_by_index:
 * @parent: the parent object to get the child from
 * @index: the child's position in the child list
 *
 * Fetches a child by its number.
 *
 * Returns: (transfer full) (nullable): the child object or %NULL if
 *     not found (index too high). Unref after usage.
 *
 * MT safe.
 */
GObject *
gst_child_proxy_get_child_by_index (GstChildProxy * parent, guint index)
{
  g_return_val_if_fail (GST_IS_CHILD_PROXY (parent), NULL);

  return (GST_CHILD_PROXY_GET_INTERFACE (parent)->get_child_by_index (parent,
          index));
}

/**
 * gst_child_proxy_get_children_count:
 * @parent: the parent object
 *
 * Gets the number of child objects this parent contains.
 *
 * Returns: the number of child objects
 *
 * MT safe.
 */
guint
gst_child_proxy_get_children_count (GstChildProxy * parent)
{
  g_return_val_if_fail (GST_IS_CHILD_PROXY (parent), 0);

  return (GST_CHILD_PROXY_GET_INTERFACE (parent)->get_children_count (parent));
}

/**
 * gst_child_proxy_lookup:
 * @object: child proxy object to lookup the property in
 * @name: name of the property to look up
 * @target: (out) (allow-none) (transfer full): pointer to a #GObject that
 *     takes the real object to set property on
 * @pspec: (out) (allow-none) (transfer none): pointer to take the #GParamSpec
 *     describing the property
 *
 * Looks up which object and #GParamSpec would be effected by the given @name.
 *
 * MT safe.
 *
 * Returns: %TRUE if @target and @pspec could be found. %FALSE otherwise. In that
 * case the values for @pspec and @target are not modified. Unref @target after
 * usage. For plain GObjects @target is the same as @object.
 */
gboolean
gst_child_proxy_lookup (GstChildProxy * object, const gchar * name,
    GObject ** target, GParamSpec ** pspec)
{
  GObject *obj;
  gboolean res = FALSE;
  gchar **names, **current;

  g_return_val_if_fail (GST_IS_CHILD_PROXY (object), FALSE);
  g_return_val_if_fail (name != NULL, FALSE);

  obj = g_object_ref (object);

  current = names = g_strsplit (name, "::", -1);
  /* find the owner of the property */
  while (current[1]) {
    GObject *next;

    if (!GST_IS_CHILD_PROXY (obj)) {
      GST_INFO
          ("object %s is not a parent, so you cannot request a child by name %s",
          (GST_IS_OBJECT (obj) ? GST_OBJECT_NAME (obj) : ""), current[0]);
      break;
    }
    next = gst_child_proxy_get_child_by_name (GST_CHILD_PROXY (obj),
        current[0]);
    if (!next) {
      GST_INFO ("no such object %s", current[0]);
      break;
    }
    g_object_unref (obj);
    obj = next;
    current++;
  }

  /* look for psec */
  if (current[1] == NULL) {
    GParamSpec *spec =
        g_object_class_find_property (G_OBJECT_GET_CLASS (obj), current[0]);
    if (spec == NULL) {
      GST_INFO ("no param spec named %s", current[0]);
    } else {
      if (pspec)
        *pspec = spec;
      if (target) {
        g_object_ref (obj);
        *target = obj;
      }
      res = TRUE;
    }
  }
  g_object_unref (obj);
  g_strfreev (names);
  return res;
}

/**
 * gst_child_proxy_get_property:
 * @object: object to query
 * @name: name of the property
 * @value: (out caller-allocates): a #GValue that should take the result.
 *
 * Gets a single property using the GstChildProxy mechanism.
 * You are responsible for freeing it by calling g_value_unset()
 */
void
gst_child_proxy_get_property (GstChildProxy * object, const gchar * name,
    GValue * value)
{
  GParamSpec *pspec;
  GObject *target;

  g_return_if_fail (GST_IS_CHILD_PROXY (object));
  g_return_if_fail (name != NULL);
  g_return_if_fail (G_IS_VALUE (value));

  if (!gst_child_proxy_lookup (object, name, &target, &pspec))
    goto not_found;

  g_object_get_property (target, pspec->name, value);
  g_object_unref (target);

  return;

not_found:
  {
    g_warning ("no property %s in object %s", name,
        (GST_IS_OBJECT (object) ? GST_OBJECT_NAME (object) : ""));
    return;
  }
}

/**
 * gst_child_proxy_get_valist:
 * @object: the object to query
 * @first_property_name: name of the first property to get
 * @var_args: return location for the first property, followed optionally by more name/return location pairs, followed by %NULL
 *
 * Gets properties of the parent object and its children.
 */
void
gst_child_proxy_get_valist (GstChildProxy * object,
    const gchar * first_property_name, va_list var_args)
{
  const gchar *name;
  gchar *error = NULL;
  GValue value = { 0, };
  GParamSpec *pspec;
  GObject *target;

  g_return_if_fail (GST_IS_CHILD_PROXY (object));

  name = first_property_name;

  /* iterate over pairs */
  while (name) {
    if (!gst_child_proxy_lookup (object, name, &target, &pspec))
      goto not_found;

    g_value_init (&value, pspec->value_type);
    g_object_get_property (target, pspec->name, &value);
    g_object_unref (target);

    G_VALUE_LCOPY (&value, var_args, 0, &error);
    if (error)
      goto cant_copy;
    g_value_unset (&value);
    name = va_arg (var_args, gchar *);
  }
  return;

not_found:
  {
    g_warning ("no property %s in object %s", name,
        (GST_IS_OBJECT (object) ? GST_OBJECT_NAME (object) : ""));
    return;
  }
cant_copy:
  {
    g_warning ("error copying value %s in object %s: %s", pspec->name,
        (GST_IS_OBJECT (object) ? GST_OBJECT_NAME (object) : ""), error);
    g_value_unset (&value);
    return;
  }
}

/**
 * gst_child_proxy_get:
 * @object: the parent object
 * @first_property_name: name of the first property to get
 * @...: return location for the first property, followed optionally by more name/return location pairs, followed by %NULL
 *
 * Gets properties of the parent object and its children.
 */
void
gst_child_proxy_get (GstChildProxy * object, const gchar * first_property_name,
    ...)
{
  va_list var_args;

  g_return_if_fail (GST_IS_CHILD_PROXY (object));

  va_start (var_args, first_property_name);
  gst_child_proxy_get_valist (object, first_property_name, var_args);
  va_end (var_args);
}

/**
 * gst_child_proxy_set_property:
 * @object: the parent object
 * @name: name of the property to set
 * @value: new #GValue for the property
 *
 * Sets a single property using the GstChildProxy mechanism.
 */
void
gst_child_proxy_set_property (GstChildProxy * object, const gchar * name,
    const GValue * value)
{
  GParamSpec *pspec;
  GObject *target;

  g_return_if_fail (GST_IS_CHILD_PROXY (object));
  g_return_if_fail (name != NULL);
  g_return_if_fail (G_IS_VALUE (value));

  if (!gst_child_proxy_lookup (object, name, &target, &pspec))
    goto not_found;

  g_object_set_property (target, pspec->name, value);
  g_object_unref (target);
  return;

not_found:
  {
    g_warning ("cannot set property %s on object %s", name,
        (GST_IS_OBJECT (object) ? GST_OBJECT_NAME (object) : ""));
    return;
  }
}

/**
 * gst_child_proxy_set_valist:
 * @object: the parent object
 * @first_property_name: name of the first property to set
 * @var_args: value for the first property, followed optionally by more name/value pairs, followed by %NULL
 *
 * Sets properties of the parent object and its children.
 */
void
gst_child_proxy_set_valist (GstChildProxy * object,
    const gchar * first_property_name, va_list var_args)
{
  const gchar *name;
  gchar *error = NULL;
  GValue value = { 0, };
  GParamSpec *pspec;
  GObject *target;

  g_return_if_fail (GST_IS_CHILD_PROXY (object));

  name = first_property_name;

  /* iterate over pairs */
  while (name) {
    if (!gst_child_proxy_lookup (object, name, &target, &pspec))
      goto not_found;

    G_VALUE_COLLECT_INIT (&value, pspec->value_type, var_args,
        G_VALUE_NOCOPY_CONTENTS, &error);

    if (error)
      goto cant_copy;

    g_object_set_property (target, pspec->name, &value);
    g_object_unref (target);

    g_value_unset (&value);
    name = va_arg (var_args, gchar *);
  }
  return;

not_found:
  {
    g_warning ("no property %s in object %s", name,
        (GST_IS_OBJECT (object) ? GST_OBJECT_NAME (object) : ""));
    return;
  }
cant_copy:
  {
    g_warning ("error copying value %s in object %s: %s", pspec->name,
        (GST_IS_OBJECT (object) ? GST_OBJECT_NAME (object) : ""), error);
    g_value_unset (&value);
    g_object_unref (target);
    return;
  }
}

/**
 * gst_child_proxy_set:
 * @object: the parent object
 * @first_property_name: name of the first property to set
 * @...: value for the first property, followed optionally by more name/value pairs, followed by %NULL
 *
 * Sets properties of the parent object and its children.
 */
void
gst_child_proxy_set (GstChildProxy * object, const gchar * first_property_name,
    ...)
{
  va_list var_args;

  g_return_if_fail (GST_IS_CHILD_PROXY (object));

  va_start (var_args, first_property_name);
  gst_child_proxy_set_valist (object, first_property_name, var_args);
  va_end (var_args);
}

/**
 * gst_child_proxy_child_added:
 * @parent: the parent object
 * @child: the newly added child
 * @name: the name of the new child
 *
 * Emits the "child-added" signal.
 */
void
gst_child_proxy_child_added (GstChildProxy * parent, GObject * child,
    const gchar * name)
{
  g_signal_emit (parent, signals[CHILD_ADDED], 0, child, name);
}

/**
 * gst_child_proxy_child_removed:
 * @parent: the parent object
 * @child: the removed child
 * @name: the name of the old child
 *
 * Emits the "child-removed" signal.
 */
void
gst_child_proxy_child_removed (GstChildProxy * parent, GObject * child,
    const gchar * name)
{
  g_signal_emit (parent, signals[CHILD_REMOVED], 0, child, name);
}

/* gobject methods */

static void
gst_child_proxy_class_init (gpointer g_class, gpointer class_data)
{
  GstChildProxyInterface *iface = (GstChildProxyInterface *) g_class;

  iface->get_child_by_name = gst_child_proxy_default_get_child_by_name;
}

static void
gst_child_proxy_base_init (gpointer g_class)
{
  static gboolean initialized = FALSE;

  if (!initialized) {
    /* create interface signals and properties here. */
    /**
     * GstChildProxy::child-added:
     * @child_proxy: the #GstChildProxy
     * @object: the #GObject that was added
     * @name: the name of the new child
     *
     * Will be emitted after the @object was added to the @child_proxy.
     */
    signals[CHILD_ADDED] =
        g_signal_new ("child-added", G_TYPE_FROM_CLASS (g_class),
        G_SIGNAL_RUN_FIRST, G_STRUCT_OFFSET (GstChildProxyInterface,
            child_added), NULL, NULL, g_cclosure_marshal_generic, G_TYPE_NONE,
        2, G_TYPE_OBJECT, G_TYPE_STRING);

    /**
     * GstChildProxy::child-removed:
     * @child_proxy: the #GstChildProxy
     * @object: the #GObject that was removed
     * @name: the name of the old child
     *
     * Will be emitted after the @object was removed from the @child_proxy.
     */
    signals[CHILD_REMOVED] =
        g_signal_new ("child-removed", G_TYPE_FROM_CLASS (g_class),
        G_SIGNAL_RUN_FIRST, G_STRUCT_OFFSET (GstChildProxyInterface,
            child_removed), NULL, NULL, g_cclosure_marshal_generic, G_TYPE_NONE,
        2, G_TYPE_OBJECT, G_TYPE_STRING);

    initialized = TRUE;
  }
}

GType
gst_child_proxy_get_type (void)
{
  static volatile gsize type = 0;

  if (g_once_init_enter (&type)) {
    GType _type;
    static const GTypeInfo info = {
      sizeof (GstChildProxyInterface),
      gst_child_proxy_base_init,        /* base_init */
      NULL,                     /* base_finalize */
      gst_child_proxy_class_init,       /* class_init */
      NULL,                     /* class_finalize */
      NULL,                     /* class_data */
      0,
      0,                        /* n_preallocs */
      NULL                      /* instance_init */
    };

    _type =
        g_type_register_static (G_TYPE_INTERFACE, "GstChildProxy", &info, 0);

    g_type_interface_add_prerequisite (_type, G_TYPE_OBJECT);
    g_once_init_leave (&type, (gsize) _type);
  }
  return type;
}