Handle edits while playing precisely.

This avoids stuck notes if active notes are edited, but without stopping all
active notes in the region on any edit as before.

This implementation injects note ons in places that aren't actually note
starts.  Depending on how percussive the instrument is, this may not be
desired.  In the future, an option for this would be an improvement, but there
are other places where "start notes in the middle" is a reasonable option.  I
think that should be handled universally if we're to do it at all, so not
considering it a part of this fix for now.

1 files changed, 9 insertions, 4 deletions

diff --git a/libs/ardour/midi_source.cc b/libs/ardour/midi_source.cc
index 8d3b130594..47cfb1b0a0 100644
--- a/libs/ardour/midi_source.cc
+++ b/libs/ardour/midi_source.cc
@@ -177,10 +177,10 @@ MidiSource::update_length (framecnt_t)
 }
 
 void
-MidiSource::invalidate (const Lock& lock)
+MidiSource::invalidate (const Lock& lock, std::set<Evoral::Sequence<Evoral::Beats>::WeakNotePtr>* notes)
 {
 	_model_iter_valid = false;
-	_model_iter.invalidate();
+	_model_iter.invalidate(notes);
 }
 
 framecnt_t
@@ -201,10 +201,15 @@ MidiSource::midi_read (const Lock&                        lm,
 	if (_model) {
 		// Find appropriate model iterator
 		Evoral::Sequence<Evoral::Beats>::const_iterator& i = _model_iter;
-		if (_last_read_end == 0 || start != _last_read_end || !_model_iter_valid) {
+		const bool linear_read = _last_read_end != 0 && start == _last_read_end;
+		if (!linear_read || !_model_iter_valid) {
 			// Cached iterator is invalid, search for the first event past start
-			i                 = _model->begin(converter.from(start), false, filtered);
+			i = _model->begin(converter.from(start), false, filtered,
+			                  linear_read ? &_model->active_notes() : NULL);
 			_model_iter_valid = true;
+			if (!linear_read) {
+				_model->active_notes().clear();
+			}
 		}
 
 		_last_read_end = start + cnt;