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, 145 insertions, 0 deletions

diff --git a/libs/ardour/note_fixer.cc b/libs/ardour/note_fixer.cc
new file mode 100644
index 0000000000..749d873779
--- /dev/null
+++ b/libs/ardour/note_fixer.cc
@@ -0,0 +1,145 @@
+/*
+    Copyright (C) 2015 Paul Davis
+    Author: David Robillard
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include "evoral/EventList.hpp"
+
+#include "ardour/beats_frames_converter.h"
+#include "ardour/midi_state_tracker.h"
+#include "ardour/note_fixer.h"
+#include "ardour/tempo.h"
+
+namespace ARDOUR {
+
+NoteFixer::~NoteFixer()
+{
+	clear();
+}
+
+void
+NoteFixer::clear()
+{
+	for (Events::iterator i = _events.begin(); i != _events.end(); ++i) {
+		delete *i;
+	}
+}
+
+void
+NoteFixer::prepare(TempoMap&                          tempo_map,
+                   const MidiModel::NoteDiffCommand*  cmd,
+                   const framepos_t                   origin,
+                   const framepos_t                   pos,
+                   std::set< boost::weak_ptr<Note> >& active_notes)
+{
+	typedef MidiModel::NoteDiffCommand Command;
+
+	BeatsFramesConverter converter(tempo_map, origin);
+
+	for (Command::NoteList::const_iterator i = cmd->removed_notes().begin();
+	     i != cmd->removed_notes().end(); ++i) {
+		if (note_is_active(converter, *i, pos)) {
+			/* Deleted note spans the end of the latest read, so we will never
+			   read its off event.  Emit a note off to prevent a stuck note. */
+			_events.push_back(copy_event(pos, (*i)->off_event()));
+			active_notes.erase(*i);
+		}
+	}
+
+	for (Command::NoteList::const_iterator i = cmd->added_notes().begin();
+	     i != cmd->added_notes().end(); ++i) {
+		if (note_is_active(converter, *i, pos)) {
+			/* Added note spans the end of the latest read, so we missed its on
+			   event.  Emit note on immediately to make the state consistent. */
+			_events.push_back(copy_event(pos, (*i)->on_event()));
+			active_notes.insert(*i);
+		}
+	}
+
+	for (Command::ChangeList::const_iterator i = cmd->changes().begin();
+	     i != cmd->changes().end(); ++i) {
+		if (!note_is_active(converter, i->note, pos)) {
+			/* Note is not currently active, no compensation needed. */
+			continue;
+		}
+
+		/* Changed note spans the end of the latest read. */
+		if (i->property == Command::NoteNumber) {
+			/* Note number has changed, end the old note. */
+			_events.push_back(copy_event(pos, i->note->off_event()));
+
+			/* Start a new note on the new note number.  The same note object
+			   is active, so we leave active_notes alone. */
+			Event* on = copy_event(pos, i->note->on_event());
+			on->buffer()[1] = (uint8_t)i->new_value.get_int();
+			_events.push_back(on);
+		} else if (i->property == Command::StartTime &&
+		           converter.to(i->new_value.get_beats()) >= pos) {
+			/* Start time has moved from before to after the end of the
+			   latest read, end the old note. */
+			_events.push_back(copy_event(pos, i->note->off_event()));
+			active_notes.erase(i->note);
+		} else if (i->property == Command::Length &&
+		           converter.to(i->note->time() + i->new_value.get_beats()) < pos) {
+			/* Length has shortened to before the end of the latest read,
+			   end the note. */
+			_events.push_back(copy_event(pos, i->note->off_event()));
+			active_notes.erase(i->note);
+		} else if (i->property == Command::Channel) {
+			/* Channel has changed, end the old note. */
+			_events.push_back(copy_event(pos, i->note->off_event()));
+
+			/* Start a new note on the new channel.  See number change above. */
+			Event* on = copy_event(pos, i->note->on_event());
+			on->buffer()[0] &= 0xF0;
+			on->buffer()[0] |= (uint8_t)i->new_value.get_int();
+			_events.push_back(on);
+		}
+	}
+}
+
+void
+NoteFixer::emit(Evoral::EventSink<framepos_t>& dst,
+                framepos_t                     pos,
+                MidiStateTracker&              tracker)
+{
+	for (Events::iterator i = _events.begin(); i != _events.end(); ++i) {
+		dst.write(pos, (*i)->event_type(), (*i)->size(), (*i)->buffer());
+		tracker.track(**i);
+		delete *i;
+	}
+	_events.clear();
+}
+
+NoteFixer::Event*
+NoteFixer::copy_event(framepos_t time, const Evoral::Event<Evoral::Beats>& ev)
+{
+	return new Event(ev.event_type(), time, ev.size(), ev.buffer());
+}
+
+bool
+NoteFixer::note_is_active(const BeatsFramesConverter& converter,
+                          boost::shared_ptr<Note>     note,
+                          framepos_t                  pos)
+{
+	const framepos_t start_time = converter.to(note->time());
+	const framepos_t end_time   = converter.to(note->end_time());
+
+	return (start_time < pos && end_time >= pos);
+}
+
+} // namespace ARDOUR