nlecomposition: Add a 'query-position' signal

In order to get the precise position of the pipeline, the only
way is to ask the 'application' to query the pipeline position and
use it.

ges/ges-internal.h

@@ -320,8 +320,9 @@ G_GNUC_INTERNAL void ges_track_element_split_bindings (GESTrackElement *element,
 						       guint64 position);
 
 G_GNUC_INTERNAL GstElement *ges_source_create_topbin (const gchar * bin_name, GstElement * sub_element, ...);
-
-G_GNUC_INTERNAL void ges_track_set_caps (GESTrack *track, const GstCaps *caps);
+G_GNUC_INTERNAL void ges_track_set_caps                (GESTrack *track,
+                                                        const GstCaps *caps);
+G_GNUC_INTERNAL GstElement * ges_track_get_composition (GESTrack *track);
 
 
 /*********************************************

ges/ges-pipeline.c

@@ -52,6 +52,8 @@ typedef struct
   GstPad *srcpad;               /* Timeline source pad */
   GstPad *playsinkpad;
   GstPad *encodebinpad;
+
+  guint query_position_id;
 } OutputChain;
 
 
@@ -629,6 +631,18 @@ no_track:
   }
 }
 
+static GstClockTime
+_query_position_cb (GstElement * composition, GESPipeline * self)
+{
+  gint64 position;
+
+  if (gst_element_query_position (GST_ELEMENT (self), GST_FORMAT_TIME,
+          &position))
+    return position;
+
+  return GST_CLOCK_TIME_NONE;
+}
+
 static void
 _link_track (GESPipeline * self, GESTrack * track)
 {
@@ -673,6 +687,10 @@ _link_track (GESPipeline * self, GESTrack * track)
   if (chain->tee)
     return;
 
+  chain->query_position_id =
+      g_signal_connect (ges_track_get_composition (track), "query-position",
+      G_CALLBACK (_query_position_cb), self);
+
   chain->srcpad = pad;
   gst_object_unref (pad);
 
@@ -835,6 +853,11 @@ _unlink_track (GESPipeline * self, GESTrack * track)
   gst_object_unref (peer);
   gst_element_set_state (chain->tee, GST_STATE_NULL);
   gst_bin_remove (GST_BIN (self), chain->tee);
+  if (chain->query_position_id) {
+    g_signal_handler_disconnect (ges_track_get_composition (track),
+        chain->query_position_id);
+    chain->query_position_id = 0;
+  }
 
   self->priv->chains = g_list_remove (self->priv->chains, chain);
   g_free (chain);

ges/ges-track.c

@@ -309,6 +309,13 @@ composition_duration_cb (GstElement * composition,
   }
 }
 
+/* Internal */
+GstElement *
+ges_track_get_composition (GESTrack * track)
+{
+  return track->priv->composition;
+}
+
 /* FIXME: Find out how to avoid doing this "hack" using the GDestroyNotify
  * function pointer in the trackelements_by_start GSequence
  *

ges/nle/nlecomposition.c

@@ -68,6 +68,7 @@ enum
 {
   COMMIT_SIGNAL,
   COMMITED_SIGNAL,
+  QUERY_POSITION_SIGNAL,
   LAST_SIGNAL
 };
 
@@ -907,6 +908,22 @@ nle_composition_class_init (NleCompositionClass * klass)
       0, NULL, NULL, g_cclosure_marshal_generic, G_TYPE_NONE, 1,
       G_TYPE_BOOLEAN);
 
+  /**
+   * NleComposition::query-position
+   * @comp: a #NleComposition
+   *
+   * A signal that *has* to be connected and which should return the current
+   * position of the pipeline.
+   *
+   * This signal is used in order to know the current position of the whole
+   * pipeline so it is user's responsability to give that answer as there
+   * is no other way to precisely know the position in the whole pipeline.
+   */
+  _signals[QUERY_POSITION_SIGNAL] =
+      g_signal_new ("query-position", G_TYPE_FROM_CLASS (klass),
+      G_SIGNAL_RUN_LAST | G_SIGNAL_NO_RECURSE,
+      0, NULL, NULL, g_cclosure_marshal_generic, G_TYPE_UINT64, 0, NULL);
+
   useless = GST_DEBUG_FUNCPTR (_seek_pipeline_func);
   useless = GST_DEBUG_FUNCPTR (_remove_object_func);
   useless = GST_DEBUG_FUNCPTR (_add_object_func);
@@ -1340,10 +1357,19 @@ get_current_position (NleComposition * comp)
   gboolean res;
   gint64 value = GST_CLOCK_TIME_NONE;
 
-  GstPad *peer = gst_pad_get_peer (NLE_OBJECT (comp)->srcpad);
+  GstPad *peer;
+
+  g_signal_emit (comp, _signals[QUERY_POSITION_SIGNAL], 0, &value);
+
+  if (value >= 0) {
+    GST_DEBUG_OBJECT (comp, "Got position %" GST_TIME_FORMAT,
+        GST_TIME_ARGS (value));
+
+    return value;
+  }
 
   /* Try querying position downstream */
-
+  peer = gst_pad_get_peer (NLE_OBJECT (comp)->srcpad);
   if (peer) {
     res = gst_pad_query_position (peer, GST_FORMAT_TIME, &value);
     gst_object_unref (peer);