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, 2 insertions, 0 deletions

diff --git a/libs/ardour/ardour/midi_region.h b/libs/ardour/ardour/midi_region.h
index 197dcdbe6c..5a1dfe0b44 100644
--- a/libs/ardour/ardour/midi_region.h
+++ b/libs/ardour/ardour/midi_region.h
@@ -61,6 +61,8 @@ class LIBARDOUR_API MidiRegion : public Region
 
 	~MidiRegion();
 
+	bool do_export (std::string path) const;
+
 	boost::shared_ptr<MidiRegion> clone (std::string path = std::string()) const;
 	boost::shared_ptr<MidiRegion> clone (boost::shared_ptr<MidiSource>) const;