ges:clip: Add a method to look for a list of TrackElement-s

+ Add unit tests to check it works properly.

API:
  + ges_clip_find_track_elements

docs/libs/ges-sections.txt

@@ -497,6 +497,7 @@ GESCreateTrackElementsFunc
 GESFillTrackElementFunc
 ges_clip_get_layer
 ges_clip_find_track_element
+ges_clip_find_track_elements
 ges_clip_add_asset
 ges_clip_get_top_effects
 ges_clip_get_top_effect_position

ges/ges-clip.c

@@ -1424,4 +1424,58 @@ ges_clip_add_asset (GESClip * clip, GESAsset * asset)
     return NULL;
 
   return element;
+
+}
+
+/**
+ * ges_clip_find_track_elements:
+ * @clip: a #GESClip
+ * @track: (allow-none): a #GESTrack or NULL
+ * @track_type: a #GESTrackType indicating the type of tracks in which elements
+ * should be searched.
+ * @type: a #GType indicating the type of track element you are looking
+ * for or %G_TYPE_NONE if you do not care about the track type.
+ *
+ * Finds all the #GESTrackElement controlled by @clip that is used in @track. You
+ * may optionally specify a GType to further narrow search criteria.
+ *
+ * Returns: (transfer full) (element-type GESTrackElement): a #GList of the
+ * #GESTrackElement contained in @clip.
+ * The refcount of the objects will be increased. The user will have to
+ * unref each #GESTrackElement and free the #GList.
+ */
+
+GList *
+ges_clip_find_track_elements (GESClip * clip, GESTrack * track,
+    GESTrackType track_type, GType type)
+{
+  GList *tmp;
+  GESTrack *tmptrack;
+  GESTrackElement *otmp;
+  GESTrackElement *foundElement;
+
+  GList *ret = NULL;
+
+  g_return_val_if_fail (GES_IS_CLIP (clip), NULL);
+  g_return_val_if_fail (!(track == NULL && type == G_TYPE_NONE &&
+          track_type == GES_TRACK_TYPE_UNKNOWN), NULL);
+
+  for (tmp = GES_CONTAINER_CHILDREN (clip); tmp; tmp = g_list_next (tmp)) {
+    otmp = (GESTrackElement *) tmp->data;
+
+    if ((type != G_TYPE_NONE) && !G_TYPE_CHECK_INSTANCE_TYPE (tmp->data, type))
+      continue;
+
+    tmptrack = ges_track_element_get_track (otmp);
+    if (((track != NULL && tmptrack == track)) ||
+        (track_type != GES_TRACK_TYPE_UNKNOWN
+            && tmptrack->type == track_type)) {
+
+      foundElement = GES_TRACK_ELEMENT (tmp->data);
+
+      ret = g_list_append (ret, gst_object_ref (foundElement));
+    }
+  }
+
+  return ret;
 }

ges/ges-clip.h

@@ -147,6 +147,8 @@ void              ges_clip_set_supported_formats  (GESClip *clip, GESTrackType
 GESTrackElement*  ges_clip_add_asset              (GESClip *clip, GESAsset *asset);
 GESTrackElement*  ges_clip_find_track_element     (GESClip *clip, GESTrack *track,
                                                    GType type);
+GList *           ges_clip_find_track_elements    (GESClip * clip, GESTrack * track,
+                                                   GESTrackType track_type, GType type);
 
 /****************************************************
  *                     Layer                        *

tests/check/ges/clip.c

@@ -361,6 +361,72 @@ GST_START_TEST (test_clip_refcount_remove_child)
 
 GST_END_TEST;
 
+GST_START_TEST (test_clip_find_track_element)
+{
+  GESClip *clip;
+  GList *foundelements;
+  GESTimeline *timeline;
+  GESTrack *track, *track1, *track2;
+
+  GESTrackElement *effect, *effect1, *effect2, *foundelem;
+
+  ges_init ();
+
+  clip = GES_CLIP (ges_test_clip_new ());
+  track = GES_TRACK (ges_audio_track_new ());
+  track1 = GES_TRACK (ges_audio_track_new ());
+  track2 = GES_TRACK (ges_video_track_new ());
+
+  timeline = ges_timeline_new ();
+  fail_unless (ges_timeline_add_track (timeline, track));
+  fail_unless (ges_timeline_add_track (timeline, track1));
+  fail_unless (ges_timeline_add_track (timeline, track2));
+
+  effect = GES_TRACK_ELEMENT (ges_effect_new ("identity"));
+  fail_unless (ges_track_add_element (track, effect));
+  fail_unless (ges_container_add (GES_CONTAINER (clip),
+          GES_TIMELINE_ELEMENT (effect)));
+
+  effect1 = GES_TRACK_ELEMENT (ges_effect_new ("identity"));
+  fail_unless (ges_track_add_element (track1, effect1));
+  fail_unless (ges_container_add (GES_CONTAINER (clip),
+          GES_TIMELINE_ELEMENT (effect1)));
+
+  effect2 = GES_TRACK_ELEMENT (ges_effect_new ("identity"));
+  fail_unless (ges_track_add_element (track2, effect2));
+  fail_unless (ges_container_add (GES_CONTAINER (clip),
+          GES_TIMELINE_ELEMENT (effect2)));
+
+  foundelem = ges_clip_find_track_element (clip, track, G_TYPE_NONE);
+  fail_unless (foundelem == effect);
+  gst_object_unref (foundelem);
+
+  foundelem = ges_clip_find_track_element (clip, NULL, GES_TYPE_SOURCE);
+  fail_unless (foundelem == NULL);
+
+  foundelements = ges_clip_find_track_elements (clip, NULL,
+      GES_TRACK_TYPE_AUDIO, G_TYPE_NONE);
+  fail_unless_equals_int (g_list_length (foundelements), 2);
+  g_list_free_full (foundelements, gst_object_unref);
+
+  foundelements = ges_clip_find_track_elements (clip, NULL,
+      GES_TRACK_TYPE_VIDEO, G_TYPE_NONE);
+  fail_unless_equals_int (g_list_length (foundelements), 1);
+  g_list_free_full (foundelements, gst_object_unref);
+
+  foundelements = ges_clip_find_track_elements (clip, track,
+      GES_TRACK_TYPE_VIDEO, G_TYPE_NONE);
+  fail_unless_equals_int (g_list_length (foundelements), 2);
+  fail_unless (g_list_find (foundelements, effect2) != NULL,
+      "In the video track");
+  fail_unless (g_list_find (foundelements, effect2) != NULL, "In 'track'");
+  g_list_free_full (foundelements, gst_object_unref);
+
+  gst_object_unref (timeline);
+}
+
+GST_END_TEST;
+
 static Suite *
 ges_suite (void)
 {
@@ -373,6 +439,7 @@ ges_suite (void)
   tcase_add_test (tc_chain, test_split_object);
   tcase_add_test (tc_chain, test_clip_group_ungroup);
   tcase_add_test (tc_chain, test_clip_refcount_remove_child);
+  tcase_add_test (tc_chain, test_clip_find_track_element);
 
   return s;
 }