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random: Add explanation about TimelineObject<=>TrackObject mapping

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This commit is contained in:
Edward Hervey 2010-12-16 19:24:52 +01:00
parent 73209e1f21
commit d7ae369084
1 changed files with 45 additions and 2 deletions
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47
docs/random/mapping.txt
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@ -10,7 +10,7 @@ TrackObject/TimelineObject basic properties (hereafter position):
Use Cases:
A TimelineObject can be tracking one or many TrackObject(s).
A TimelineObject tracks one or many TrackObject(s).
When the TimelineObject position is modified we might need
to cascade those changes to the controlled TrackObject(s) if those
@ -52,5 +52,48 @@ Main Problem:
Design:
TBD
The TimelineObject listen to TrackObject 'notify' signals
When it sets a property on its trackobjects, it 'ignores' all
notifications that happen while setting them.
Setting a property on a TrackObject will see its property changed,
and then it emits a notify with the modified property.
TrackObject::locked
ges_track_object_set_locked()
ges_track_object_is_locked()
Mapping {
GESTrackObject *object;
gint64 start_offset;
gint64 duration_offset;
gint64 inpoint_offset;
gint32 priority_offset;
/* Track ??? */
}
P : property
V : value
TimelineObject set_property(P,V)
ignore_notifies = TRUE
parent.P = V
foreach child in trackobjects:
if child.is_locked():
child.set_property(P, parent.P + mapping(child).P_offset)
ignore_notifies = FALSE
TimelineObject child 'notify::P' handler:
if ignore_notifies:
return
if not child.is_locked():
mapping(child).P_offset = timeline.P - child.P
else:
TimelineObject.set_property(P, child value + mapping(child).P_offset)
TrackObject set_property(P, V)
update the property locally (P = V)
emit 'notify::P' signal
TODO : When do we resync the parent values to have minimal offsets ?