gstreamer/docs/random/scenarios
2015-06-25 10:54:13 +02:00

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SCENARIOS
* Adding a TimelineObject to a TimelineLayer
--------------------------------------------
* Create a Timeline
* Create a Track
* Add the track to the Timeline (==> ges_timeline_add_track (track);)
The Timeline adds the Track to itself (i.e. gst_bin_add())
'track-added' is emitted
* Create a TimelineLayer
* Add the TimelineLayer to the Timeline (ges_timeline_add_layer (layer);)
The Timeline takes a reference on the layer and stores it
The Timeline tells the TimelineLayer that it now belongs to the given Timeline (weak reference)
==> ges_timeline_layer_set_timeline ();
'layer-added' is emitted
* Create a TimelineObject
* Add the TimelineObject to the TimelineLayer (ges_timeline_layer_add_object (object);)
The TimelineLayer takes a reference on the TimelineObject and stores it
The timelineLayer tells the TimelineObject that it now belongs to the given layer (weak reference)
==> ges_timeline_object_set_layer ();
'object-added' is emitted by TimelineLayer
The Timeline requests a new TrackObject from the new TimelineObject for each Track
==> ges_timeline_object_create_track_object (track)
The TimelineObject calls the 'create_track_object' virtual method with the given track
Example implementation
Create a GESTrackSource
(GESTimelineObject is a constructor property of track objects)
A GESTrackObject CAN NOT EXIST WITHOUT A GESTimelineObject !
The Timeline adds the newly created TrackObject to the Track
==> ges_track_add_object (track, trackobject);
Set the track on the TrackObject
==> ges_track_object_set_track (track)
The GESTrackObject can create the NleObject
Methods
-------
[ GESTimeline ]
* gboolean
ges_timeline_add_track (GESTimeline * timeline, GESTrack * track);
* The Timeline adds the track to itself (gst_bin_add ()) # reference implicitely taken
* The Timeline adds the track to its list of tracked tracks
* The Timeline sets the Timeline on the track
=> ges_track_set_timeline (GESTrack * track, GESTimeline * timeline);
Just sets the timeline field of the track.
* emits 'track-added'
* gboolean
ges_timeline_add_layer (GESTimeline * timeline, GESTimelineLayer * layer);
* The Timeline takes a reference on the layer and stores it
* The Timeline tells the Layer that it now belongs to the given Timeline
=> ges_timeline_layer_set_timeline (GESTimelineLayer * layer, GESTimeline * timeline);
Just sets the timeline field of the layer.
* Connect to the layer's 'object-added' signal
* emits 'layer-added'
* GESTimeline's
callback for GESTimelineLayer::object-added (GESTimelineLayer * layer, GESTimelineObject * object);
* For each GESTrack in the Timeline:
* The timeline requests a new TrackObject for the new TimelineObject for each Track
trackobj = ges_timeline_object_create_track_object (timelineobj, track);
* The timeline adds the newly created TrackObject to the track
ges_track_add_object (track, trackobj);
[ GESTimelineLayer ]
* gboolean
ges_timeline_layer_add_object (GESTimelineLayer * layer, GESTimelineObject * object);
* The TimelineLayer takes a reference on the TimelineObject and stores it
* The TimelineLayer tells the TimelineObject it now belongs to the given Layer
=> ges_timeline_object_set_layer (GESTimelineObject * object, GESTimelineLayer * layer);
Just sets the layer field of the timeline object.
* emits 'object-added'
[ GESTimelineObject ]
* GESTrackObject *
ges_timeline_object_create_track_object (GESTimelineObject * object, GESTrack * track);
* The TimelineObject calls the 'create_track_object' virtual method
* The TimelineObject sets the TimelineObject on the new TrackObject
=> ges_track_object_set_timeline_object (track_object, timeline_object);
Just sets the timeline-object field of the TrackObject
* Return the newly created GESTrackObject
* Virtual-method for GESTimelineObject::create_track_object (GESTimelineObject * object, GESTrack * track);
* Create a track object of the proper type
Ex (for a source) :
return ges_track_source_new();
* gboolean
ges_timeline_object_fill_track_object (GESTimelineObject *tlo, GESTrackObject *tro, GstElement *nleobj);
* up to the implementation :)
[ GESTrack ]
* gboolean
ges_track_add_object (GESTrack * track, GESTrackObject * object);
* Set the track on the track_object
ges_track_object_set_track (object, track);
* Add the NleObject of the TrackObject to the composition
gst_bin_add (track->composition, object->nleobject);
[ GESTrackObject ]
* gboolean
ges_track_object_set_track (GESTrackObject * object, GESTrack * track);
* Set the track field of the TrackObject
* if no NleObject is available yet:
* Call the 'create_gnl_object' virtual method
* Virtual-method for GESTrackObject::create_gnl_object
* Create a NleObject of the proper type
Ex : nleobject = gst_element_factory_make("nlesource", NULL);
* Ask the TimelineObject to fill in the NleObject
=> ges_timeline_object_fill_track_object (GESTimelineObject * tlo, GESTrackObject * tro, GstElement * nleobj);