GESTrackObject: Add create_element vmethod

API: GESTrackObjectClass::gnlobject_factorytype
API: GESTrackObjectClass::create_element

Most track objects are only specific by the contents of the gnlobject,
therefore move the 'create_element' vmethod which was already present
in some subclasses to the top-level class.

Also make the code more robust

ges/ges-track-audio-test-source.c

@@ -51,20 +51,17 @@ static void ges_track_audio_test_source_get_property (GObject * object, guint
 static void ges_track_audio_test_source_set_property (GObject * object, guint
     property_id, const GValue * value, GParamSpec * pspec);
 
-static GstElement *ges_track_audio_test_source_create_element (GESTrackSource *
+static GstElement *ges_track_audio_test_source_create_element (GESTrackObject *
     self);
 
 static void
 ges_track_audio_test_source_class_init (GESTrackAudioTestSourceClass * klass)
 {
-  GObjectClass *object_class;
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
-  GESTrackSourceClass *bg_class;
+  GESTrackObjectClass *bg_class = GES_TRACK_OBJECT_CLASS (klass);
 
   g_type_class_add_private (klass, sizeof (GESTrackAudioTestSourcePrivate));
 
-  object_class = G_OBJECT_CLASS (klass);
-  bg_class = GES_TRACK_SOURCE_CLASS (klass);
-
   object_class->get_property = ges_track_audio_test_source_get_property;
   object_class->set_property = ges_track_audio_test_source_set_property;
 
@@ -102,7 +99,7 @@ ges_track_audio_test_source_set_property (GObject * object,
 }
 
 static GstElement *
-ges_track_audio_test_source_create_element (GESTrackSource * trksrc)
+ges_track_audio_test_source_create_element (GESTrackObject * trksrc)
 {
   GESTrackAudioTestSource *self;
   GstElement *ret;
@@ -122,7 +119,7 @@ ges_track_audio_test_source_set_freq (GESTrackAudioTestSource * self,
   GstElement *element;
 
   self->freq = freq;
-  element = ((GESTrackSource *) self)->element;
+  element = ((GESTrackObject *) self)->element;
   if (element)
     g_object_set (element, "freq", (gdouble) freq, NULL);
 }
@@ -134,7 +131,7 @@ ges_track_audio_test_source_set_volume (GESTrackAudioTestSource * self,
   GstElement *element;
 
   self->volume = volume;
-  element = ((GESTrackSource *) self)->element;
+  element = ((GESTrackObject *) self)->element;
   if (element)
     g_object_set (element, "volume", (gdouble) volume, NULL);
 }

ges/ges-track-audio-transition.c

@@ -47,7 +47,7 @@ enum
 static void
 ges_track_audio_transition_duration_changed (GESTrackObject * self, guint64);
 
-static GstElement *ges_track_audio_transition_create_element (GESTrackTransition
+static GstElement *ges_track_audio_transition_create_element (GESTrackObject
     * self);
 
 static void ges_track_audio_transition_dispose (GObject * object);
@@ -65,13 +65,11 @@ ges_track_audio_transition_class_init (GESTrackAudioTransitionClass * klass)
 {
   GObjectClass *object_class;
   GESTrackObjectClass *toclass;
-  GESTrackTransitionClass *pclass;
 
   g_type_class_add_private (klass, sizeof (GESTrackAudioTransitionPrivate));
 
   object_class = G_OBJECT_CLASS (klass);
   toclass = GES_TRACK_OBJECT_CLASS (klass);
-  pclass = GES_TRACK_TRANSITION_CLASS (klass);
 
   object_class->get_property = ges_track_audio_transition_get_property;
   object_class->set_property = ges_track_audio_transition_set_property;
@@ -80,7 +78,7 @@ ges_track_audio_transition_class_init (GESTrackAudioTransitionClass * klass)
 
   toclass->duration_changed = ges_track_audio_transition_duration_changed;
 
-  pclass->create_element = ges_track_audio_transition_create_element;
+  toclass->create_element = ges_track_audio_transition_create_element;
 
 }
 
@@ -166,7 +164,7 @@ link_element_to_mixer_with_volume (GstBin * bin, GstElement * element,
 }
 
 static GstElement *
-ges_track_audio_transition_create_element (GESTrackTransition * object)
+ges_track_audio_transition_create_element (GESTrackObject * object)
 {
   GESTrackAudioTransition *self;
   GstElement *topbin, *iconva, *iconvb, *oconv;

ges/ges-track-image-source.c

@@ -111,7 +111,7 @@ pad_added_cb (GstElement * timeline, GstPad * pad, GstElement * scale)
 }
 
 static GstElement *
-ges_track_image_source_create_element (GESTrackSource * object)
+ges_track_image_source_create_element (GESTrackObject * object)
 {
   GstElement *bin, *source, *scale, *freeze, *iconv;
   GstPad *src, *target;
@@ -151,7 +151,7 @@ static void
 ges_track_image_source_class_init (GESTrackImageSourceClass * klass)
 {
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
-  GESTrackSourceClass *source_class = GES_TRACK_SOURCE_CLASS (klass);
+  GESTrackObjectClass *gesobj_class = GES_TRACK_OBJECT_CLASS (klass);
 
   g_type_class_add_private (klass, sizeof (GESTrackImageSourcePrivate));
 
@@ -167,7 +167,7 @@ ges_track_image_source_class_init (GESTrackImageSourceClass * klass)
   g_object_class_install_property (object_class, PROP_URI,
       g_param_spec_string ("uri", "URI", "uri of the resource",
           NULL, G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY));
-  source_class->create_element = ges_track_image_source_create_element;
+  gesobj_class->create_element = ges_track_image_source_create_element;
 }
 
 static void

ges/ges-track-object.c

@@ -497,10 +497,84 @@ gnlobject_active_cb (GstElement * gnlobject, GParamSpec * arg G_GNUC_UNUSED,
 
 /* default 'create_gnl_object' virtual method implementation */
 static gboolean
-ges_track_object_create_gnl_object_func (GESTrackObject * object)
+ges_track_object_create_gnl_object_func (GESTrackObject * self)
 {
+  GESTrackObjectClass *klass = NULL;
+  GstElement *child = NULL;
+  GstElement *gnlobject;
 
-  return FALSE;
+  klass = GES_TRACK_OBJECT_GET_CLASS (self);
+
+  if (G_UNLIKELY (self->gnlobject != NULL))
+    goto already_have_gnlobject;
+
+  if (G_UNLIKELY (klass->gnlobject_factorytype == NULL))
+    goto no_gnlfactory;
+
+  GST_DEBUG ("Creating a supporting gnlobject of type '%s'",
+      klass->gnlobject_factorytype);
+
+  gnlobject = gst_element_factory_make (klass->gnlobject_factorytype, NULL);
+
+  if (G_UNLIKELY (gnlobject == NULL))
+    goto no_gnlobject;
+
+  if (klass->create_element) {
+    GST_DEBUG ("Calling subclass 'create_element' vmethod");
+    child = klass->create_element (self);
+
+    if (G_UNLIKELY (!child))
+      goto child_failure;
+
+    if (!gst_bin_add (GST_BIN (gnlobject), child))
+      goto add_failure;
+
+    GST_DEBUG ("Succesfully got the element to put in the gnlobject");
+    self->element = child;
+  }
+
+  self->gnlobject = gnlobject;
+
+  GST_DEBUG ("done");
+  return TRUE;
+
+
+  /* ERROR CASES */
+
+already_have_gnlobject:
+  {
+    GST_ERROR ("Already controlling a GnlObject %s",
+        GST_ELEMENT_NAME (self->gnlobject));
+    return FALSE;
+  }
+
+no_gnlfactory:
+  {
+    GST_ERROR ("No GESTrackObject::gnlobject_factorytype implementation!");
+    return FALSE;
+  }
+
+no_gnlobject:
+  {
+    GST_ERROR ("Error creating a gnlobject of type '%s'",
+        klass->gnlobject_factorytype);
+    return FALSE;
+  }
+
+child_failure:
+  {
+    GST_ERROR ("create_element returned NULL");
+    gst_object_unref (gnlobject);
+    return FALSE;
+  }
+
+add_failure:
+  {
+    GST_ERROR ("Error adding the contents to the gnlobject");
+    gst_object_unref (child);
+    gst_object_unref (gnlobject);
+    return FALSE;
+  }
 }
 
 static gboolean

ges/ges-track-object.h

@@ -132,7 +132,8 @@ struct _GESTrackObject {
   guint32 pending_gnl_priority;
   gboolean pending_active;
 
-  GstElement *gnlobject;
+  GstElement *gnlobject;  /* The GnlObject */
+  GstElement *element;	  /* The element contained in the gnlobject (can be NULL) */
 
   GESTrackObjectPrivate *priv;
 
@@ -142,7 +143,12 @@ struct _GESTrackObject {
 
 /**
  * GESTrackObjectClass:
+ * @gnlobject_factorytype: name of the GNonLin GStElementFactory type to use.
  * @create_gnl_object: method to create the GNonLin container object.
+ * Create and fill the gnlobject and set it to GESTrackObject->gnlobject.
+ * The default implementation will create an object of type @gnlobject_factorytype
+ * and call @create_element.
+ * @create_element: method to return the GstElement to put in the gnlobject.
  * @start_changed: start property of gnlobject has changed
  * @media_start_changed: media-start property of gnlobject has changed
  * @duration_changed: duration property glnobject has changed
@@ -158,7 +164,9 @@ struct _GESTrackObjectClass {
 
   /*< public >*/
   /* virtual methods for subclasses */
+  const gchar *gnlobject_factorytype;
   gboolean (*create_gnl_object) (GESTrackObject * object);
+  GstElement* (*create_element) (GESTrackObject * object);
 
   void (*start_changed) (GESTrackObject *object, guint64 start);
   void (*media_start_changed) (GESTrackObject *object, guint64 media_start);

ges/ges-track-operation.c

@@ -36,36 +36,6 @@ struct _GESTrackOperationPrivate
   void *nothing;
 };
 
-static gboolean
-ges_track_operation_create_gnl_object (GESTrackObject * object)
-{
-  GESTrackOperationClass *klass = NULL;
-  GESTrackOperation *self = NULL;
-  GstElement *child = NULL;
-  GstElement *gnlobject;
-
-  self = GES_TRACK_OPERATION (object);
-  klass = GES_TRACK_OPERATION_GET_CLASS (self);
-
-  gnlobject = gst_element_factory_make ("gnloperation", NULL);
-
-  if (klass->create_element) {
-    child = klass->create_element (self);
-
-    if (G_UNLIKELY (!child)) {
-      GST_ERROR ("create_element returned NULL");
-      return TRUE;
-    }
-
-    gst_bin_add (GST_BIN (gnlobject), child);
-    self->element = child;
-  }
-
-  object->gnlobject = gnlobject;
-
-  return TRUE;
-}
-
 static void
 ges_track_operation_class_init (GESTrackOperationClass * klass)
 {
@@ -73,8 +43,7 @@ ges_track_operation_class_init (GESTrackOperationClass * klass)
 
   g_type_class_add_private (klass, sizeof (GESTrackOperationPrivate));
 
-  track_class->create_gnl_object = ges_track_operation_create_gnl_object;
+  track_class->gnlobject_factorytype = "gnloperation";
-  klass->create_element = NULL;
 }
 
 static void

ges/ges-track-operation.h

@@ -57,8 +57,6 @@ struct _GESTrackOperation {
   /*< private >*/
   GESTrackObject parent;
 
-  GstElement *element;
-
   GESTrackOperationPrivate *priv;
 
   /* Padding for API extension */
@@ -67,17 +65,12 @@ struct _GESTrackOperation {
 
 /**
  * GESTrackOperationClass:
- * @create_element: virtual method which creates the GStreamer element for
- * this object
  */
 
 struct _GESTrackOperationClass {
   /*< private >*/
   GESTrackObjectClass parent_class;
 
-  /*< public >*/
-  GstElement *(*create_element) (GESTrackOperation *);
-
   /*< private >*/
   /* Padding for API extension */
   gpointer _ges_reserved[GES_PADDING];

ges/ges-track-source.c

@@ -35,36 +35,6 @@ struct _GESTrackSourcePrivate
   void *nothing;
 };
 
-static gboolean
-ges_track_source_create_gnl_object (GESTrackObject * object)
-{
-  GESTrackSourceClass *klass = NULL;
-  GESTrackSource *self = NULL;
-  GstElement *child = NULL;
-  GstElement *gnlobject;
-
-  self = GES_TRACK_SOURCE (object);
-  klass = GES_TRACK_SOURCE_GET_CLASS (self);
-
-  gnlobject = gst_element_factory_make ("gnlsource", NULL);
-
-  if (klass->create_element) {
-    child = klass->create_element (self);
-
-    if (G_UNLIKELY (!child)) {
-      GST_ERROR ("create_element returned NULL");
-      return TRUE;
-    }
-
-    gst_bin_add (GST_BIN (gnlobject), child);
-    self->element = child;
-  }
-
-  object->gnlobject = gnlobject;
-
-  return TRUE;
-}
-
 static void
 ges_track_source_class_init (GESTrackSourceClass * klass)
 {
@@ -72,8 +42,8 @@ ges_track_source_class_init (GESTrackSourceClass * klass)
 
   g_type_class_add_private (klass, sizeof (GESTrackSourcePrivate));
 
-  track_class->create_gnl_object = ges_track_source_create_gnl_object;
+  track_class->gnlobject_factorytype = "gnlsource";
-  klass->create_element = NULL;
+  track_class->create_element = NULL;
 }
 
 static void

ges/ges-track-source.h

@@ -57,8 +57,6 @@ struct _GESTrackSource {
   /*< private >*/
   GESTrackObject parent;
 
-  GstElement *element;
-
   GESTrackSourcePrivate *priv;
 
   /* Padding for API extension */
@@ -67,18 +65,12 @@ struct _GESTrackSource {
 
 /**
  * GESTrackSourceClass:
- * @create_element: virtual method which creates the GStreamer element for
- * this object
- *
  */
 
 struct _GESTrackSourceClass {
   /*< private >*/
   GESTrackObjectClass parent_class;
 
-  /*< public >*/
-  GstElement *(*create_element) (GESTrackSource *);
-
   /*< private >*/
   /* Padding for API extension */
   gpointer _ges_reserved[GES_PADDING];

ges/ges-track-text-overlay.c

@@ -54,20 +54,17 @@ static void ges_track_text_overlay_get_property (GObject * object, guint
 static void ges_track_text_overlay_set_property (GObject * object, guint
     property_id, const GValue * value, GParamSpec * pspec);
 
-static GstElement *ges_track_text_overlay_create_element (GESTrackOperation
+static GstElement *ges_track_text_overlay_create_element (GESTrackObject
     * self);
 
 static void
 ges_track_text_overlay_class_init (GESTrackTextOverlayClass * klass)
 {
-  GObjectClass *object_class;
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
-  GESTrackOperationClass *bg_class;
+  GESTrackObjectClass *bg_class = GES_TRACK_OBJECT_CLASS (klass);
 
   g_type_class_add_private (klass, sizeof (GESTrackTextOverlayPrivate));
 
-  object_class = G_OBJECT_CLASS (klass);
-  bg_class = GES_TRACK_OPERATION_CLASS (klass);
-
   object_class->get_property = ges_track_text_overlay_get_property;
   object_class->set_property = ges_track_text_overlay_set_property;
   object_class->dispose = ges_track_text_overlay_dispose;
@@ -136,7 +133,7 @@ ges_track_text_overlay_set_property (GObject * object,
 }
 
 static GstElement *
-ges_track_text_overlay_create_element (GESTrackOperation * object)
+ges_track_text_overlay_create_element (GESTrackObject * object)
 {
   GstElement *ret, *text, *iconv, *oconv;
   GstPad *src_target, *sink_target;

ges/ges-track-title-source.c

@@ -50,19 +50,16 @@ static void ges_track_title_src_get_property (GObject * object, guint
 static void ges_track_title_src_set_property (GObject * object, guint
     property_id, const GValue * value, GParamSpec * pspec);
 
-static GstElement *ges_track_title_src_create_element (GESTrackSource * self);
+static GstElement *ges_track_title_src_create_element (GESTrackObject * self);
 
 static void
 ges_track_title_src_class_init (GESTrackTitleSourceClass * klass)
 {
-  GObjectClass *object_class;
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
-  GESTrackSourceClass *bg_class;
+  GESTrackObjectClass *bg_class = GES_TRACK_OBJECT_CLASS (klass);
 
   g_type_class_add_private (klass, sizeof (GESTrackTitleSourcePrivate));
 
-  object_class = G_OBJECT_CLASS (klass);
-  bg_class = GES_TRACK_SOURCE_CLASS (klass);
-
   object_class->get_property = ges_track_title_src_get_property;
   object_class->set_property = ges_track_title_src_set_property;
   object_class->dispose = ges_track_title_src_dispose;
@@ -130,7 +127,7 @@ ges_track_title_src_set_property (GObject * object,
 }
 
 static GstElement *
-ges_track_title_src_create_element (GESTrackSource * object)
+ges_track_title_src_create_element (GESTrackObject * object)
 {
   GESTrackTitleSource *self = GES_TRACK_TITLE_SOURCE (object);
   GstElement *topbin, *background, *text;

ges/ges-track-transition.c

@@ -36,52 +36,11 @@ struct _GESTrackTransitionPrivate
   void *nothing;
 };
 
-GstElement *ges_track_transition_create_element (GESTrackTransition * self);
-
-static gboolean
-ges_track_transition_create_gnl_object (GESTrackObject * object)
-{
-  GESTrackTransition *self;
-  GESTrackTransitionClass *klass;
-  GstElement *element;
-  gchar *name;
-  static gint tnum = 0;
-
-  self = GES_TRACK_TRANSITION (object);
-  klass = GES_TRACK_TRANSITION_GET_CLASS (object);
-
-  name = g_strdup_printf ("transition-operation%d", tnum++);
-  object->gnlobject = gst_element_factory_make ("gnloperation", name);
-  g_free (name);
-
-  g_object_set (object->gnlobject, "priority", 0, NULL);
-
-  element = klass->create_element (self);
-  if (!GST_IS_ELEMENT (element))
-    return FALSE;
-
-  gst_bin_add (GST_BIN (object->gnlobject), element);
-
-  return TRUE;
-}
-
-GstElement *
-ges_track_transition_create_element (GESTrackTransition * self)
-{
-  GST_WARNING ("transitions don't handle this track type!");
-
-  return NULL;
-}
 
 static void
 ges_track_transition_class_init (GESTrackTransitionClass * klass)
 {
-  GESTrackObjectClass *track_class = GES_TRACK_OBJECT_CLASS (klass);
-
   g_type_class_add_private (klass, sizeof (GESTrackTransitionPrivate));
-
-  track_class->create_gnl_object = ges_track_transition_create_gnl_object;
-  klass->create_element = ges_track_transition_create_element;
 }
 
 static void
@@ -89,5 +48,4 @@ ges_track_transition_init (GESTrackTransition * self)
 {
   self->priv = G_TYPE_INSTANCE_GET_PRIVATE (self,
       GES_TYPE_TRACK_TRANSITION, GESTrackTransitionPrivate);
-
 }

ges/ges-track-transition.h

@@ -71,16 +71,12 @@ struct _GESTrackTransition
 
 /**
  * GESTrackTransitionClass:
- * @create_element: return the element that should be controlled by the transition
  */
 
 struct _GESTrackTransitionClass {
   /*< private >*/
   GESTrackOperationClass parent_class;
   
-  /*< public >*/
-  GstElement* (*create_element) (GESTrackTransition *self);
-
   /*< private >*/
   /* Padding for API extension */
   gpointer _ges_reserved[GES_PADDING];

ges/ges-track-video-test-source.c

@@ -36,19 +36,17 @@ struct _GESTrackVideoTestSourcePrivate
   void *nothing;
 };
 
-static GstElement *ges_track_video_test_source_create_element (GESTrackSource *
+static GstElement *ges_track_video_test_source_create_element (GESTrackObject *
     self);
 
 static void
 ges_track_video_test_source_class_init (GESTrackVideoTestSourceClass * klass)
 {
-  GESTrackSourceClass *track_source_class;
+  GESTrackObjectClass *track_object_class = GES_TRACK_OBJECT_CLASS (klass);
 
   g_type_class_add_private (klass, sizeof (GESTrackVideoTestSourcePrivate));
 
-  track_source_class = GES_TRACK_SOURCE_CLASS (klass);
+  track_object_class->create_element =
-
-  track_source_class->create_element =
       ges_track_video_test_source_create_element;
 }
 
@@ -62,7 +60,7 @@ ges_track_video_test_source_init (GESTrackVideoTestSource * self)
 }
 
 static GstElement *
-ges_track_video_test_source_create_element (GESTrackSource * self)
+ges_track_video_test_source_create_element (GESTrackObject * self)
 {
   GstElement *ret;
   gint pattern;
@@ -81,7 +79,7 @@ ges_track_video_test_source_set_pattern (GESTrackVideoTestSource
 {
   GstElement *element;
 
-  element = GES_TRACK_SOURCE (self)->element;
+  element = GES_TRACK_OBJECT (self)->element;
   self->pattern = pattern;
 
   if (element)

ges/ges-track-video-transition.c

@@ -53,7 +53,7 @@ static void
 ges_track_video_transition_duration_changed (GESTrackObject * self,
     guint64 duration);
 
-static GstElement *ges_track_video_transition_create_element (GESTrackTransition
+static GstElement *ges_track_video_transition_create_element (GESTrackObject
     * self);
 
 static void ges_track_video_transition_dispose (GObject * object);
@@ -71,13 +71,11 @@ ges_track_video_transition_class_init (GESTrackVideoTransitionClass * klass)
 {
   GObjectClass *object_class;
   GESTrackObjectClass *toclass;
-  GESTrackTransitionClass *pclass;
 
   g_type_class_add_private (klass, sizeof (GESTrackVideoTransitionPrivate));
 
   object_class = G_OBJECT_CLASS (klass);
   toclass = GES_TRACK_OBJECT_CLASS (klass);
-  pclass = GES_TRACK_TRANSITION_CLASS (klass);
 
   object_class->get_property = ges_track_video_transition_get_property;
   object_class->set_property = ges_track_video_transition_set_property;
@@ -85,8 +83,7 @@ ges_track_video_transition_class_init (GESTrackVideoTransitionClass * klass)
   object_class->finalize = ges_track_video_transition_finalize;
 
   toclass->duration_changed = ges_track_video_transition_duration_changed;
-
+  toclass->create_element = ges_track_video_transition_create_element;
-  pclass->create_element = ges_track_video_transition_create_element;
 }
 
 static void
@@ -169,7 +166,7 @@ ges_track_video_transition_set_property (GObject * object,
 }
 
 static GstElement *
-ges_track_video_transition_create_element (GESTrackTransition * object)
+ges_track_video_transition_create_element (GESTrackObject * object)
 {
   GstElement *topbin, *iconva, *iconvb, *oconv;
   GObject *target = NULL;