feat(tracker): add support for a MIDI controller to the standalone tracker

Closes #132.

tracker/action.go

@@ -1,6 +1,7 @@
 package tracker
 
 import (
+	"fmt"
 	"os"
 
 	"github.com/vsariola/sointu"
@@ -444,6 +445,14 @@ func (m *Model) Cancel() Action      { return Allow(func() { m.dialog = NoDialog
 func (m *Model) Export() Action      { return Allow(func() { m.dialog = Export }) }
 func (m *Model) ExportFloat() Action { return Allow(func() { m.dialog = ExportFloatExplorer }) }
 func (m *Model) ExportInt16() Action { return Allow(func() { m.dialog = ExportInt16Explorer }) }
+func (m *Model) SelectMidiInput(item MIDIDevicer) Action {
+	return Allow(func() {
+		if !m.MIDI.OpenInputDevice(item) {
+			message := fmt.Sprintf("Could not open MIDI device %s\n", item)
+			m.Alerts().Add(message, Error)
+		}
+	})
+}
 
 func (m *Model) completeAction(checkSave bool) {
 	if checkSave && m.d.ChangedSinceSave {

tracker/gioui/songpanel.go

@@ -48,12 +48,15 @@ type SongPanel struct {
 	followOnHint, followOffHint string
 	panicHint                   string
 	loopOffHint, loopOnHint     string
+
+	// Midi menu items
+	midiMenuItems []MenuItem
 }
 
 func NewSongPanel(model *tracker.Model) *SongPanel {
 	ret := &SongPanel{
-		MenuBar:        make([]widget.Clickable, 2),
-		Menus:          make([]Menu, 2),
+		MenuBar:        make([]widget.Clickable, 3),
+		Menus:          make([]Menu, 3),
 		BPM:            NewNumberInput(model.BPM().Int()),
 		RowsPerPattern: NewNumberInput(model.RowsPerPattern().Int()),
 		RowsPerBeat:    NewNumberInput(model.RowsPerBeat().Int()),
@@ -81,6 +84,13 @@ func NewSongPanel(model *tracker.Model) *SongPanel {
 		{IconBytes: icons.ContentRedo, Text: "Redo", ShortcutText: keyActionMap["Redo"], Doer: model.Redo()},
 		{IconBytes: icons.ImageCrop, Text: "Remove unused data", ShortcutText: keyActionMap["RemoveUnused"], Doer: model.RemoveUnused()},
 	}
+	for input := range model.MIDI.ListInputDevices() {
+		ret.midiMenuItems = append(ret.midiMenuItems, MenuItem{
+			IconBytes: icons.ImageControlPoint,
+			Text:      input.String(),
+			Doer:      model.SelectMidiInput(input),
+		})
+	}
 	ret.rewindHint = makeHint("Rewind", "\n(%s)", "PlaySongStartUnfollow")
 	ret.playHint = makeHint("Play", " (%s)", "PlayCurrentPosUnfollow")
 	ret.stopHint = makeHint("Stop", " (%s)", "StopPlaying")
@@ -91,6 +101,7 @@ func NewSongPanel(model *tracker.Model) *SongPanel {
 	ret.followOffHint = makeHint("Follow off", " (%s)", "FollowToggle")
 	ret.loopOffHint = makeHint("Loop off", " (%s)", "LoopToggle")
 	ret.loopOnHint = makeHint("Loop on", " (%s)", "LoopToggle")
+
 	return ret
 }
 
@@ -112,6 +123,7 @@ func (t *SongPanel) layoutMenuBar(gtx C, tr *Tracker) D {
 	return layout.Flex{Axis: layout.Horizontal, Alignment: layout.End}.Layout(gtx,
 		layout.Rigid(tr.layoutMenu(gtx, "File", &t.MenuBar[0], &t.Menus[0], unit.Dp(200), t.fileMenuItems...)),
 		layout.Rigid(tr.layoutMenu(gtx, "Edit", &t.MenuBar[1], &t.Menus[1], unit.Dp(200), t.editMenuItems...)),
+		layout.Rigid(tr.layoutMenu(gtx, "MIDI", &t.MenuBar[2], &t.Menus[2], unit.Dp(200), t.midiMenuItems...)),
 	)
 }
 

tracker/gomidi/midi.go

@@ -0,0 +1,115 @@
+package gomidi
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/vsariola/sointu/tracker"
+	"gitlab.com/gomidi/midi/v2"
+	"gitlab.com/gomidi/midi/v2/drivers"
+	"gitlab.com/gomidi/midi/v2/drivers/rtmididrv"
+)
+
+type (
+	MIDIContext struct {
+		driver          *rtmididrv.Driver
+		inputAvailable  bool
+		driverAvailable bool
+		currentIn       MIDIDevicer
+		events          chan midi.Message
+	}
+	MIDIDevicer drivers.In
+)
+
+func (m *MIDIContext) ListInputDevices() <-chan tracker.MIDIDevicer {
+
+	ins, err := m.driver.Ins()
+	channel := make(chan tracker.MIDIDevicer, len(ins))
+	if err != nil {
+		m.driver.Close()
+		m.driverAvailable = false
+		return nil
+	}
+	go func() {
+		for i := 0; i < len(ins); i++ {
+			channel <- ins[i].(MIDIDevicer)
+		}
+		close(channel)
+	}()
+	return channel
+}
+
+// Open the driver.
+func CreateContext() *MIDIContext {
+	m := MIDIContext{}
+	var err error
+	m.driver, err = rtmididrv.New()
+	m.driverAvailable = err == nil
+	if m.driverAvailable {
+		m.events = make(chan midi.Message)
+	}
+	return &m
+}
+
+// Open an input device while closing the currently open if necessary.
+func (m *MIDIContext) OpenInputDevice(in tracker.MIDIDevicer) bool {
+	fmt.Printf("Opening midi device %s\n.", in)
+	if m.driverAvailable {
+		if m.currentIn == in {
+			return false
+		}
+		if m.inputAvailable && m.currentIn.IsOpen() {
+			m.currentIn.Close()
+		}
+		m.currentIn = in.(MIDIDevicer)
+		m.currentIn.Open()
+		_, err := midi.ListenTo(m.currentIn, m.HandleMessage)
+		if err != nil {
+			m.inputAvailable = false
+			return false
+		}
+	}
+	return true
+}
+
+func (m *MIDIContext) HandleMessage(msg midi.Message, timestampms int32) {
+	go func() {
+		m.events <- msg
+		time.Sleep(time.Nanosecond)
+	}()
+}
+
+func (c *MIDIContext) NextEvent() (event tracker.MIDINoteEvent, ok bool) {
+	select {
+	case msg := <-c.events:
+		{
+			var channel uint8
+			var velocity uint8
+			var key uint8
+			var controller uint8
+			var value uint8
+			if msg.GetNoteOn(&channel, &key, &velocity) {
+				return tracker.MIDINoteEvent{Frame: 0, On: true, Channel: int(channel), Note: key}, true
+			} else if msg.GetNoteOff(&channel, &key, &velocity) {
+				return tracker.MIDINoteEvent{Frame: 0, On: false, Channel: int(channel), Note: key}, true
+			} else if msg.GetControlChange(&channel, &controller, &value) {
+				fmt.Printf("CC @ Channel: %d, Controller: %d, Value: %d\n", channel, controller, value)
+			} else {
+				fmt.Printf("Unhandled MIDI message: %s\n", msg)
+			}
+		}
+	default:
+		// Note (@LeStahL): This empty select case is needed to make the implementation non-blocking.
+	}
+	return tracker.MIDINoteEvent{}, false
+}
+
+func (c *MIDIContext) BPM() (bpm float64, ok bool) {
+	return 0, false
+}
+
+func (c *MIDIContext) DestroyContext() {
+	close(c.events)
+	c.currentIn.Close()
+	c.driver.Close()
+}

tracker/model.go

@@ -75,6 +75,8 @@ type (
 
 		PlayerMessages chan PlayerMsg
 		modelMessages  chan<- interface{}
+
+		MIDI MIDIContexter
 	}
 
 	// Cursor identifies a row and a track in a song score.
@@ -120,6 +122,18 @@ type (
 	ChangeType     int
 
 	Dialog int
+
+	MIDIContexter interface {
+		ListInputDevices() <-chan MIDIDevicer
+		OpenInputDevice(item MIDIDevicer) bool
+		DestroyContext()
+		BPM() (bpm float64, ok bool)
+		NextEvent() (event MIDINoteEvent, ok bool)
+	}
+
+	MIDIDevicer interface {
+		String() string
+	}
 )
 
 const (