feat(tracker): add ability to loop part of song during playback

Closes #128.

CHANGELOG.md

@@ -5,6 +5,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## Unreleased
 ### Added
+- Ability to loop certain section of the song when playing. The loop can be set
+  by using the toggle button in the song panel, or by hitting Ctrl+L.
+  ([#128][i128])
 - Disable units temporarily. The disabled units are shown in gray and are not
   compiled into the patch and are considered for all purposes non-existent.
   Hitting Ctrl-D disables/re-enables the selected unit(s). The yaml file has
@@ -139,5 +142,6 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 [i120]: https://github.com/vsariola/sointu/issues/120
 [i121]: https://github.com/vsariola/sointu/issues/121
 [i122]: https://github.com/vsariola/sointu/issues/122
+[i128]: https://github.com/vsariola/sointu/issues/128
 [i129]: https://github.com/vsariola/sointu/issues/129
 [i130]: https://github.com/vsariola/sointu/issues/130

tracker/bool.go

@@ -20,6 +20,7 @@ type (
 	NoteTracking    Model
 	UnitSearching   Model
 	UnitDisabled    Model
+	LoopToggle      Model
 )
 
 func (v Bool) Toggle() {
@@ -43,6 +44,7 @@ func (m *Model) CommentExpanded() *CommentExpanded { return (*CommentExpanded)(m
 func (m *Model) NoteTracking() *NoteTracking       { return (*NoteTracking)(m) }
 func (m *Model) UnitSearching() *UnitSearching     { return (*UnitSearching)(m) }
 func (m *Model) UnitDisabled() *UnitDisabled       { return (*UnitDisabled)(m) }
+func (m *Model) LoopToggle() *LoopToggle           { return (*LoopToggle)(m) }
 
 // Panic methods
 
@@ -161,3 +163,20 @@ func (m *UnitDisabled) Enabled() bool {
 	}
 	return true
 }
+
+// LoopToggle methods
+
+func (m *LoopToggle) Bool() Bool  { return Bool{m} }
+func (m *LoopToggle) Value() bool { return m.d.Loop.Length > 0 }
+func (t *LoopToggle) setValue(val bool) {
+	m := (*Model)(t)
+	defer m.change("SetLoopAction", LoopChange, MinorChange)()
+	if !val {
+		m.d.Loop = Loop{}
+		return
+	}
+	l := m.OrderRows().List()
+	a, b := l.listRange()
+	m.d.Loop = Loop{a, b - a + 1}
+}
+func (m *LoopToggle) Enabled() bool { return true }

tracker/gioui/keyevent.go

@@ -69,6 +69,11 @@ func (t *Tracker) KeyEvent(e key.Event, o *op.Ops) {
 				t.Model.UnitDisabled().Bool().Toggle()
 				return
 			}
+		case "L":
+			if e.Modifiers.Contain(key.ModShortcut) {
+				t.Model.LoopToggle().Bool().Toggle()
+				return
+			}
 		case "N":
 			if e.Modifiers.Contain(key.ModShortcut) {
 				t.NewSong().Do()

tracker/gioui/note_editor.go

@@ -202,9 +202,13 @@ func (te *NoteEditor) layoutTracks(gtx C, t *Tracker) D {
 		pat := j / rpp
 		row := j % rpp
 		w := pxPatMarkWidth + pxRowMarkWidth
-		paint.ColorOp{Color: rowMarkerPatternTextColor}.Add(gtx.Ops)
 		defer op.Offset(image.Pt(0, -2)).Push(gtx.Ops).Pop()
 		if row == 0 {
+			color := rowMarkerPatternTextColor
+			if l := t.Loop(); pat >= l.Start && pat < l.Start+l.Length {
+				color = loopMarkerColor
+			}
+			paint.ColorOp{Color: color}.Add(gtx.Ops)
 			widget.Label{}.Layout(gtx, t.Theme.Shaper, trackerFont, trackerFontSize, strings.ToUpper(fmt.Sprintf("%02x", pat)), op.CallOp{})
 		}
 		defer op.Offset(image.Pt(pxPatMarkWidth, 0)).Push(gtx.Ops).Pop()

tracker/gioui/order_editor.go

@@ -81,11 +81,15 @@ func (oe *OrderEditor) Layout(gtx C, t *Tracker) D {
 	}
 
 	rowTitle := func(gtx C, j int) D {
+		w := gtx.Dp(unit.Dp(30))
 		if playPos := t.PlayPosition(); t.SongPanel.PlayingBtn.Bool.Value() && j == playPos.OrderRow {
 			paint.FillShape(gtx.Ops, patternPlayColor, clip.Rect{Max: image.Pt(gtx.Constraints.Max.X, patternCellHeight)}.Op())
 		}
-		w := gtx.Dp(unit.Dp(30))
+		color := rowMarkerPatternTextColor
-		paint.ColorOp{Color: rowMarkerPatternTextColor}.Add(gtx.Ops)
+		if l := t.Loop(); j >= l.Start && j < l.Start+l.Length {
+			color = loopMarkerColor
+		}
+		paint.ColorOp{Color: color}.Add(gtx.Ops)
 		defer op.Offset(image.Pt(0, -2)).Push(gtx.Ops).Pop()
 		widget.Label{}.Layout(gtx, t.Theme.Shaper, trackerFont, trackerFontSize, strings.ToUpper(fmt.Sprintf("%02x", j)), op.CallOp{})
 		return D{Size: image.Pt(w, patternCellHeight)}

tracker/gioui/songpanel.go

@@ -26,6 +26,7 @@ type SongPanel struct {
 	RecordBtn    *BoolClickable
 	NoteTracking *BoolClickable
 	PanicBtn     *BoolClickable
+	LoopBtn      *BoolClickable
 
 	// File menu items
 	fileMenuItems  []MenuItem
@@ -50,6 +51,7 @@ func NewSongPanel(model *tracker.Model) *SongPanel {
 		Step:           NewNumberInput(model.Step().Int()),
 		SongLength:     NewNumberInput(model.SongLength().Int()),
 		PanicBtn:       NewBoolClickable(model.Panic().Bool()),
+		LoopBtn:        NewBoolClickable(model.LoopToggle().Bool()),
 		RecordBtn:      NewBoolClickable(model.IsRecording().Bool()),
 		NoteTracking:   NewBoolClickable(model.NoteTracking().Bool()),
 		PlayingBtn:     NewBoolClickable(model.Playing().Bool()),
@@ -106,6 +108,7 @@ func (t *SongPanel) layoutSongOptions(gtx C, tr *Tracker) D {
 	playBtnStyle := ToggleIcon(tr.Theme, t.PlayingBtn, icons.AVPlayArrow, icons.AVStop, "Play (F6 / Space)", "Stop (F6 / Space)")
 	recordBtnStyle := ToggleIcon(tr.Theme, t.RecordBtn, icons.AVFiberManualRecord, icons.AVFiberSmartRecord, "Record (F7)", "Stop (F7)")
 	noteTrackBtnStyle := ToggleIcon(tr.Theme, t.NoteTracking, icons.ActionSpeakerNotesOff, icons.ActionSpeakerNotes, "Follow\nOff\n(F8)", "Follow\nOn\n(F8)")
+	loopBtnStyle := ToggleIcon(tr.Theme, t.LoopBtn, icons.NavigationArrowForward, icons.AVLoop, "Loop\nOff\n(Ctrl+L)", "Loop\nOn\n(Ctrl+L)")
 
 	return layout.Flex{Axis: layout.Vertical}.Layout(gtx,
 		layout.Rigid(func(gtx C) D {
@@ -174,6 +177,7 @@ func (t *SongPanel) layoutSongOptions(gtx C, tr *Tracker) D {
 				layout.Rigid(playBtnStyle.Layout),
 				layout.Rigid(recordBtnStyle.Layout),
 				layout.Rigid(noteTrackBtnStyle.Layout),
+				layout.Rigid(loopBtnStyle.Layout),
 			)
 		}),
 		layout.Rigid(panicBtnStyle.Layout),

tracker/gioui/theme.go

@@ -44,6 +44,7 @@ var twoBeatHighlight = color.NRGBA{R: 31, G: 51, B: 53, A: 255}
 var patternPlayColor = color.NRGBA{R: 55, G: 55, B: 61, A: 255}
 var patternTextColor = primaryColor
 var patternCellColor = color.NRGBA{R: 255, G: 255, B: 255, A: 3}
+var loopMarkerColor = color.NRGBA{R: 252, G: 186, B: 3, A: 255}
 
 var instrumentHoverColor = color.NRGBA{R: 30, G: 31, B: 38, A: 255}
 var instrumentNameColor = color.NRGBA{R: 255, G: 255, B: 255, A: 255}

tracker/gioui/tracker.go

@@ -72,7 +72,7 @@ func NewTracker(model *tracker.Model) *Tracker {
 		OctaveNumberInput: NewNumberInput(model.Octave().Int()),
 		InstrumentVoices:  NewNumberInput(model.InstrumentVoices().Int()),
 
-		TopHorizontalSplit:    &Split{Ratio: -.6},
+		TopHorizontalSplit:    &Split{Ratio: -.5},
 		BottomHorizontalSplit: &Split{Ratio: -.6},
 		VerticalSplit:         &Split{Axis: layout.Vertical},
 

tracker/model.go

@@ -36,6 +36,7 @@ type (
 		ChangedSinceSave        bool
 		RecoveryFilePath        string
 		ChangedSinceRecovery    bool
+		Loop                    Loop
 	}
 
 	Model struct {
@@ -81,6 +82,12 @@ type (
 		sointu.SongPos
 	}
 
+	// Loop identifier the order rows, which are the loop positions
+	// Length = 0 means no loop is chosen, regardless of start
+	Loop struct {
+		Start, Length int
+	}
+
 	Explore struct {
 		IsSave       bool         // true if this is a save operation, false if open operation
 		IsSong       bool         // true if this is a song, false if instrument
@@ -125,6 +132,7 @@ const (
 	ScoreChange
 	BPMChange
 	RowsPerBeatChange
+	LoopChange
 	SongChange ChangeType = PatchChange | ScoreChange | BPMChange | RowsPerBeatChange
 )
 
@@ -148,6 +156,7 @@ const maxUndo = 64
 func (m *Model) AverageVolume() Volume        { return m.avgVolume }
 func (m *Model) PeakVolume() Volume           { return m.peakVolume }
 func (m *Model) PlayPosition() sointu.SongPos { return m.playPosition }
+func (m *Model) Loop() Loop                   { return m.d.Loop }
 func (m *Model) PlaySongRow() int             { return m.d.Song.Score.SongRow(m.playPosition) }
 func (m *Model) ChangedSinceSave() bool       { return m.d.ChangedSinceSave }
 func (m *Model) Dialog() Dialog               { return m.dialog }
@@ -233,6 +242,9 @@ func (m *Model) change(kind string, t ChangeType, severity ChangeSeverity) func(
 			if m.changeType&RowsPerBeatChange != 0 {
 				m.send(RowsPerBeatMsg{m.d.Song.RowsPerBeat})
 			}
+			if m.changeType&LoopChange != 0 {
+				m.send(m.d.Loop)
+			}
 			m.undoSkipCounter++
 			var limit int
 			switch m.changeSeverity {
@@ -385,6 +397,7 @@ func (m *Model) resetSong() {
 	}
 	m.d.FilePath = ""
 	m.d.ChangedSinceSave = false
+	m.d.Loop = Loop{}
 }
 
 // send sends a message to the player

tracker/player.go

@@ -24,6 +24,7 @@ type (
 		peakVolumeMeter VolumeAnalyzer         // the volume analyzer used to calculate the peak volume
 		voiceLevels     [vm.MAX_VOICES]float32 // a level that can be used to visualize the volume of each voice
 		voices          [vm.MAX_VOICES]voice
+		loop            Loop
 
 		recState  recState  // is the recording off; are we waiting for a note; or are we recording
 		recording Recording // the recorded MIDI events and BPM
@@ -192,6 +193,10 @@ func (p *Player) advanceRow() {
 		return
 	}
 	p.songPos.PatternRow++ // advance row (this is why we subtracted one in Play())
+	if p.loop.Length > 0 && p.songPos.PatternRow >= p.song.Score.RowsPerPattern && p.songPos.OrderRow == p.loop.Start+p.loop.Length-1 {
+		p.songPos.PatternRow = 0
+		p.songPos.OrderRow = p.loop.Start
+	}
 	p.songPos = p.song.Score.Wrap(p.songPos)
 	p.send(nil) // just send volume and song row information
 	lastVoice := 0
@@ -230,6 +235,8 @@ loop:
 				p.compileOrUpdateSynth()
 			case sointu.Score:
 				p.song.Score = m
+			case Loop:
+				p.loop = m
 			case IsPlayingMsg:
 				p.playing = bool(m.bool)
 				if !p.playing {