Add a dedicated export method to MidiRegion

To export a MIDI region to a file, the code used MidiRegion::clone()
since it takes care of creating a new file-backed source with the wanted
contents. Nevertheless, it had several side-effects:
- it created and registered a new region which is confusing to users
- it only exported notes that were in the region range, but didn't
  remove the region start offset from MIDI events, essentially producing
  a spurious silence at the beginning of the exported file (this is not
  a problem for region cloning because the newly created region is made
  aware of the offset and caters for it).

Add a dedicated code path for export, that uses the new offsetting
capabilities of MidiModel::write_section_to().

1 files changed, 17 insertions, 0 deletions

diff --git a/libs/ardour/midi_source.cc b/libs/ardour/midi_source.cc
index 5b671b4a26..97bce4b1ab 100644
--- a/libs/ardour/midi_source.cc
+++ b/libs/ardour/midi_source.cc
@@ -385,6 +385,23 @@ MidiSource::mark_streaming_write_completed (const Lock& lock)
 }
 
 int
+MidiSource::export_write_to (const Lock& lock, boost::shared_ptr<MidiSource> newsrc, Evoral::Beats begin, Evoral::Beats end)
+{
+	Lock newsrc_lock (newsrc->mutex ());
+
+	if (!_model) {
+		error << string_compose (_("programming error: %1"), X_("no model for MidiSource during export"));
+		return -1;
+	}
+
+	_model->write_section_to (newsrc, newsrc_lock, begin, end, true);
+
+	newsrc->flush_midi(newsrc_lock);
+
+	return 0;
+}
+
+int
 MidiSource::write_to (const Lock& lock, boost::shared_ptr<MidiSource> newsrc, Evoral::Beats begin, Evoral::Beats end)
 {
 	Lock newsrc_lock (newsrc->mutex ());