Add a control surface MCU basic interface

Adds compatibility with:
- Play button
- Stop button
- Loop button
- Record button
- Jog wheel to select instrument

include/ControlSurface.h

@@ -0,0 +1,66 @@
+/*
+ * ControlSurface.h - Common control surface actions to lmms
+ *
+ * Copyright (c) 2025 - altrouge
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * 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 (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
+#ifndef LMMS_CONTROL_SURFACE_H
+#define LMMS_CONTROL_SURFACE_H
+
+#include <QObject>
+
+#include "lmms_export.h"
+
+namespace lmms {
+//! Implements functions linking controller to LMMS.
+class LMMS_EXPORT ControlSurface : public QObject
+{
+	Q_OBJECT
+public:
+	ControlSurface();
+
+public:
+signals:
+	void requestPlay();
+	void requestStop();
+	void requestLoop();
+	void requestRecord();
+	void requestPreviousInstrumentTrack();
+	void requestNextInstrumentTrack();
+
+	// Use slots to call from correct thread.
+private slots:
+	///! Starts playing.
+	void play();
+	///! Stops playing.
+	void stop();
+	///! Activate/deactivate the loop.
+	void loop();
+	///! Starts recording.
+	void record();
+	///! Selects previous instrument track.
+	void previousInstrumentTrack();
+	///! Selects next instrument track.
+	void nextInstrumentTrack();
+};
+} // namespace lmms
+
+#endif

include/ControlSurfaceMCU.h

@@ -0,0 +1,49 @@
+/*
+ * ControlSurfaceMCU.h - A controller to receive MIDI MCU control
+ *
+ * Copyright (c) 2025 - altrouge
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * 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 (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
+#ifndef LMMS_CONTROL_SURFACE_MCU_H
+#define LMMS_CONTROL_SURFACE_MCU_H
+
+#include "ControlSurface.h"
+#include "MidiEventProcessor.h"
+#include "MidiPort.h"
+#include "Note.h"
+
+namespace lmms {
+//! Implements the Mackie control protocol to control the DAW.
+class LMMS_EXPORT ControlSurfaceMCU : public MidiEventProcessor
+{
+public:
+	ControlSurfaceMCU(const QString& device);
+
+	void processInEvent(const MidiEvent& event, const TimePos& time = TimePos(), f_cnt_t offset = 0) override;
+	void processOutEvent(const MidiEvent& event, const TimePos& time = TimePos(), f_cnt_t offset = 0) override;
+
+private:
+	MidiPort m_midiPort;
+	ControlSurface m_controlSurface;
+};
+} // namespace lmms
+
+#endif

include/InstrumentTrack.h

@@ -240,6 +240,9 @@ class LMMS_EXPORT InstrumentTrack : public Track, public MidiEventProcessor
 
 	void autoAssignMidiDevice( bool );
 
+        /// Gets the auto assigned track (more or less the selected track).
+        static InstrumentTrack* getAutoAssignedTrack() { return InstrumentTrack::s_autoAssignedTrack; }
+
 signals:
 	void instrumentChanged();
 	void midiNoteOn( const lmms::Note& );

include/SetupDialog.h

@@ -189,6 +189,7 @@ private slots:
 	MswMap m_midiIfaceSetupWidgets;
 	trMap m_midiIfaceNames;
 	QComboBox * m_assignableMidiDevices;
+	QComboBox* m_MCUDawMidiDevices;
 	bool m_midiAutoQuantize;
 
 	// Paths settings widgets.

include/Song.h

@@ -44,6 +44,7 @@ namespace lmms
 {
 
 class AutomationTrack;
+class ControlSurfaceMCU;
 class Keymap;
 class MidiClip;
 class Scale;
@@ -378,6 +379,9 @@ class LMMS_EXPORT Song : public TrackContainer
 
 	Metronome& metronome() { return m_metronome; }
 
+	/// Set a DAW MCU surface control.
+	void setControlSurfaceMCU();
+
 public slots:
 	void playSong();
 	void record();
@@ -512,6 +516,7 @@ private slots:
 	TimePos m_exportSongEnd;
 	TimePos m_exportEffectiveLength;
 
+	std::shared_ptr<ControlSurfaceMCU> m_mcu_controller = nullptr;
 	std::shared_ptr<Scale> m_scales[MaxScaleCount];
 	std::shared_ptr<Keymap> m_keymaps[MaxKeymapCount];
 

src/core/CMakeLists.txt

@@ -14,6 +14,7 @@ set(LMMS_SRCS
 	core/Clipboard.cpp
 	core/ComboBoxModel.cpp
 	core/ConfigManager.cpp
+	core/ControlSurface.cpp
 	core/Controller.cpp
 	core/ControllerConnection.cpp
 	core/DataFile.cpp
@@ -120,6 +121,7 @@ set(LMMS_SRCS
 	core/lv2/Lv2UridMap.cpp
 	core/lv2/Lv2Worker.cpp
 
+	core/midi/ControlSurfaceMCU.cpp
 	core/midi/MidiAlsaRaw.cpp
 	core/midi/MidiAlsaSeq.cpp
 	core/midi/MidiClient.cpp

src/core/ControlSurface.cpp

@@ -0,0 +1,131 @@
+/*
+ * ControlSurface.cpp - Common control surface actions to lmms
+ *
+ * Copyright (c) 2025 - altrouge
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * 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 (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include "ControlSurface.h"
+
+#include "Engine.h"
+#include "GuiApplication.h"
+#include "InstrumentTrack.h"
+#include "MidiClip.h"
+#include "PianoRoll.h"
+#include "Song.h"
+#include "SongEditor.h"
+
+namespace lmms {
+
+ControlSurface::ControlSurface()
+{
+	QObject::connect(this, &ControlSurface::requestPlay, this, &ControlSurface::play);
+	QObject::connect(this, &ControlSurface::requestStop, this, &ControlSurface::stop);
+	QObject::connect(this, &ControlSurface::requestLoop, this, &ControlSurface::loop);
+	QObject::connect(this, &ControlSurface::requestRecord, this, &ControlSurface::record);
+	QObject::connect(
+		this, &ControlSurface::requestPreviousInstrumentTrack, this, &ControlSurface::previousInstrumentTrack);
+	QObject::connect(this, &ControlSurface::requestNextInstrumentTrack, this, &ControlSurface::nextInstrumentTrack);
+}
+
+void ControlSurface::play()
+{
+	Engine::getSong()->playSong();
+}
+
+void ControlSurface::stop()
+{
+	auto piano_roll = gui::getGUI()->pianoRoll();
+	if (piano_roll != nullptr) { piano_roll->stop(); }
+	Engine::getSong()->stop();
+}
+
+void ControlSurface::loop()
+{
+	// Activate on MidiClip for piano roll and Song for whole song.
+	auto& timeline_midi = Engine::getSong()->getTimeline(Song::PlayMode::MidiClip);
+	timeline_midi.setLoopEnabled(!timeline_midi.loopEnabled());
+	auto& timeline = Engine::getSong()->getTimeline(Song::PlayMode::Song);
+	timeline.setLoopEnabled(!timeline.loopEnabled());
+}
+
+void ControlSurface::record()
+{
+	// Get the clip.
+	auto assigned_instrument_track = InstrumentTrack::getAutoAssignedTrack();
+	if (assigned_instrument_track != nullptr)
+	{
+		std::vector<Clip*> clips;
+		auto current_time = Engine::getSong()->getPlayPos(Song::PlayMode::Song);
+		assigned_instrument_track->getClipsInRange(clips, current_time, current_time);
+		MidiClip* current_clip = nullptr;
+
+		// If there are no available clips, create a clip.
+		if (!clips.empty()) { current_clip = dynamic_cast<MidiClip*>(clips.front()); }
+		else { current_clip = dynamic_cast<MidiClip*>(assigned_instrument_track->createClip(current_time)); }
+
+		auto piano_roll = gui::getGUI()->pianoRoll();
+		piano_roll->setCurrentMidiClip(current_clip);
+		piano_roll->recordAccompany();
+	}
+}
+
+void followingInstrumentTrack(bool reverse)
+{
+	// Get the clip.
+	auto assigned_instrument_track = InstrumentTrack::getAutoAssignedTrack();
+	const auto track_list = Engine::getSong()->tracks();
+	int next = reverse ? -1 : 1;
+	if (track_list.empty()) { return; }
+
+	int start_ind = reverse ? track_list.size() - 1 : 0;
+	if (assigned_instrument_track != nullptr)
+	{
+		for (size_t ind = 0; ind < track_list.size(); ++ind)
+		{
+			if (track_list[ind] == assigned_instrument_track)
+			{
+				start_ind = (ind + track_list.size() + next) % track_list.size();
+				break;
+			}
+		}
+	}
+	for (size_t iteration = 0; iteration < track_list.size(); ++iteration)
+	{
+		size_t current_ind = (start_ind + track_list.size() + next * iteration) % track_list.size();
+		if (track_list[current_ind]->type() == Track::Type::Instrument)
+		{
+			assigned_instrument_track = dynamic_cast<InstrumentTrack*>(track_list[current_ind]);
+			assigned_instrument_track->autoAssignMidiDevice(true);
+			break;
+		}
+	}
+}
+
+void ControlSurface::previousInstrumentTrack()
+{
+	followingInstrumentTrack(true);
+}
+
+void ControlSurface::nextInstrumentTrack()
+{
+	followingInstrumentTrack(false);
+}
+} // namespace lmms

src/core/Song.cpp

@@ -37,6 +37,7 @@
 #include "ConfigManager.h"
 #include "ControllerRackView.h"
 #include "ControllerConnection.h"
+#include "ControlSurfaceMCU.h"
 #include "EnvelopeAndLfoParameters.h"
 #include "Mixer.h"
 #include "MixerView.h"
@@ -45,6 +46,7 @@
 #include "InstrumentTrack.h"
 #include "Keymap.h"
 #include "NotePlayHandle.h"
+#include "MidiClient.h"
 #include "MidiClip.h"
 #include "PatternEditor.h"
 #include "PatternStore.h"
@@ -167,8 +169,16 @@ void Song::setTempo()
 	emit tempoChanged( tempo );
 }
 
-
-
+void Song::setControlSurfaceMCU()
+{
+	m_mcu_controller.reset();
+	const QString& device = ConfigManager::inst()->value("midi", "midimcudaw");
+	// Check if the device exists
+	if (Engine::audioEngine()->midiClient()->readablePorts().indexOf(device) >= 0)
+	{
+		m_mcu_controller = std::make_shared<ControlSurfaceMCU>(device);
+	}
+}
 
 void Song::setTimeSignature()
 {
@@ -1169,6 +1179,14 @@ void Song::loadProject( const QString & fileName )
 		node = node.nextSibling();
 	}
 
+	// Set the midi MCU controller and update it when the config is updated.
+	setControlSurfaceMCU();
+	connect(ConfigManager::inst(), &ConfigManager::valueChanged,
+		[this](QString const& cls, QString const& attribute, QString const& value) {
+			if (!(cls == "midi" && attribute == "midimcudaw")) { return; }
+			setControlSurfaceMCU();
+		});
+
 	// quirk for fixing projects with broken positions of Clips inside pattern tracks
 	Engine::patternStore()->fixIncorrectPositions();