feat(tracker): adding, setting, unsetting and deleting units

compiler/encoded_patch.go

@@ -33,6 +33,9 @@ func Encode(patch *sointu.Patch, featureSet FeatureSet) (*EncodedPatch, error) {
 			return nil, errors.New("Each instrument must have at least 1 voice")
 		}
 		for _, unit := range instr.Units {
+			if unit.Type == "" { // empty units are just ignored & skipped
+				continue
+			}
 			if unit.Type == "oscillator" && unit.Parameters["type"] == 4 {
 				s := SampleOffset{Start: uint32(unit.Parameters["start"]), LoopStart: uint16(unit.Parameters["loopstart"]), LoopLength: uint16(unit.Parameters["looplength"])}
 				index, ok := sampleOffsetMap[s]

tracker/defaultsong.go

@@ -1,14 +1,65 @@
 package tracker
 
-import "github.com/vsariola/sointu"
+import (
+	"sort"
+
+	"github.com/vsariola/sointu"
+)
+
+var defaultUnits = map[string]sointu.Unit{
+	"envelope":   {Type: "envelope", Parameters: map[string]int{"stereo": 0, "attack": 64, "decay": 64, "sustain": 64, "release": 64, "gain": 64}},
+	"oscillator": {Type: "oscillator", Parameters: map[string]int{"stereo": 0, "transpose": 64, "detune": 64, "phase": 0, "color": 64, "shape": 64, "gain": 64, "type": sointu.Sine}},
+	"noise":      {Type: "noise", Parameters: map[string]int{"stereo": 0, "shape": 64, "gain": 64}},
+	"mulp":       {Type: "mulp", Parameters: map[string]int{"stereo": 0}},
+	"mul":        {Type: "mul", Parameters: map[string]int{"stereo": 0}},
+	"add":        {Type: "add", Parameters: map[string]int{"stereo": 0}},
+	"addp":       {Type: "addp", Parameters: map[string]int{"stereo": 0}},
+	"push":       {Type: "push", Parameters: map[string]int{"stereo": 0}},
+	"pop":        {Type: "pop", Parameters: map[string]int{"stereo": 0}},
+	"xch":        {Type: "xch", Parameters: map[string]int{"stereo": 0}},
+	"receive":    {Type: "receive", Parameters: map[string]int{"stereo": 0}},
+	"loadnote":   {Type: "loadnote", Parameters: map[string]int{"stereo": 0}},
+	"loadval":    {Type: "loadval", Parameters: map[string]int{"stereo": 0, "value": 64}},
+	"pan":        {Type: "pan", Parameters: map[string]int{"stereo": 0, "panning": 64}},
+	"gain":       {Type: "gain", Parameters: map[string]int{"stereo": 0, "gain": 64}},
+	"invgain":    {Type: "invgain", Parameters: map[string]int{"stereo": 0, "invgain": 64}},
+	"crush":      {Type: "crush", Parameters: map[string]int{"stereo": 0, "resolution": 64}},
+	"clip":       {Type: "clip", Parameters: map[string]int{"stereo": 0}},
+	"hold":       {Type: "hold", Parameters: map[string]int{"stereo": 0, "holdfreq": 64}},
+	"distort":    {Type: "distort", Parameters: map[string]int{"stereo": 0, "drive": 64}},
+	"filter":     {Type: "filter", Parameters: map[string]int{"stereo": 0, "frequency": 64, "resonance": 64, "lowpass": 1, "bandpass": 0, "highpass": 0, "negbandpass": 0, "neghighpass": 0}},
+	"out":        {Type: "out", Parameters: map[string]int{"stereo": 1, "gain": 64}},
+	"outaux":     {Type: "outaux", Parameters: map[string]int{"stereo": 1, "outgain": 64, "auxgain": 64}},
+	"aux":        {Type: "aux", Parameters: map[string]int{"stereo": 1, "gain": 64, "channel": 2}},
+	"delay": {Type: "delay",
+		Parameters: map[string]int{"damp": 0, "dry": 128, "feedback": 96, "notetracking": 0, "pregain": 40, "stereo": 0},
+		VarArgs: []int{1116, 1188, 1276, 1356, 1422, 1492, 1556, 1618,
+			1140, 1212, 1300, 1380, 1446, 1516, 1580, 1642,
+		}},
+	"in":         {Type: "in", Parameters: map[string]int{"stereo": 1, "channel": 2}},
+	"speed":      {Type: "speed", Parameters: map[string]int{}},
+	"compressor": {Type: "compressor", Parameters: map[string]int{"stereo": 0, "attack": 64, "release": 64, "invgain": 64, "threshold": 64, "ratio": 64}},
+}
+
+var allUnits []string
+
+func init() {
+	allUnits = make([]string, 0, len(sointu.UnitTypes))
+	for k := range sointu.UnitTypes {
+		allUnits = append(allUnits, k)
+	}
+	sort.Strings(allUnits)
+}
 
 var defaultInstrument = sointu.Instrument{
 	NumVoices: 1,
 	Units: []sointu.Unit{
-		{Type: "envelope", Parameters: map[string]int{"stereo": 1, "attack": 32, "decay": 32, "sustain": 64, "release": 64, "gain": 64}},
-		{Type: "oscillator", Parameters: map[string]int{"stereo": 1, "transpose": 64, "detune": 64, "phase": 0, "color": 128, "shape": 64, "gain": 64, "type": sointu.Sine}},
-		{Type: "mulp", Parameters: map[string]int{"stereo": 1}},
-		{Type: "out", Parameters: map[string]int{"stereo": 1, "gain": 64}},
+		defaultUnits["envelope"],
+		defaultUnits["oscillator"],
+		defaultUnits["mulp"],
+		defaultUnits["delay"],
+		defaultUnits["pan"],
+		defaultUnits["out"],
 	},
 }
 
@@ -20,16 +71,5 @@ var defaultSong = sointu.Song{
 		{NumVoices: 2, Sequence: []byte{0, 0, 0, 1}, Patterns: [][]byte{{64, 0, 68, 0, 32, 0, 0, 0, 75, 0, 78, 0, 0, 0, 0, 0}, {64, 0, 68, 0, 32, 0, 0, 0, 75, 0, 75, 0, 75, 0, 80, 0}}},
 		{NumVoices: 2, Sequence: []byte{0, 0, 0, 1}, Patterns: [][]byte{{0, 0, 64, 0, 68, 0, 32, 0, 0, 0, 75, 0, 78, 0, 0, 0}, {32, 0, 64, 0, 68, 0, 32, 0, 0, 0, 75, 0, 68, 0, 68, 0}}},
 	},
-	Patch: sointu.Patch{
-		Instruments: []sointu.Instrument{{NumVoices: 4, Units: []sointu.Unit{
-			{Type: "envelope", Parameters: map[string]int{"stereo": 1, "attack": 32, "decay": 32, "sustain": 64, "release": 64, "gain": 64}},
-			{Type: "oscillator", Parameters: map[string]int{"stereo": 1, "transpose": 64, "detune": 64, "phase": 0, "color": 128, "shape": 64, "gain": 64, "type": sointu.Sine}},
-			{Type: "mulp", Parameters: map[string]int{"stereo": 1}},
-			{Type: "delay",
-				Parameters: map[string]int{"damp": 0, "dry": 128, "feedback": 96, "notetracking": 0, "pregain": 40, "stereo": 1},
-				VarArgs: []int{1116, 1188, 1276, 1356, 1422, 1492, 1556, 1618,
-					1140, 1212, 1300, 1380, 1446, 1516, 1580, 1642,
-				}},
-			{Type: "out", Parameters: map[string]int{"stereo": 1, "gain": 64}},
-		}}}},
+	Patch: sointu.Patch{Instruments: []sointu.Instrument{{NumVoices: 4, Units: defaultInstrument.Units}}},
 }

tracker/instruments.go

@@ -2,7 +2,8 @@ package tracker
 
 import (
 	"fmt"
-	"sort"
+	"image"
+	"image/color"
 
 	"gioui.org/layout"
 	"gioui.org/op"
@@ -52,7 +53,7 @@ func (t *Tracker) layoutInstruments() layout.Widget {
 
 func (t *Tracker) layoutInstrumentHeader() layout.Widget {
 	headerBg := func(gtx C) D {
-		paint.FillShape(gtx.Ops, trackMenuSurfaceColor, clip.Rect{
+		paint.FillShape(gtx.Ops, instrumentSurfaceColor, clip.Rect{
 			Max: gtx.Constraints.Min,
 		}.Op())
 		return layout.Dimensions{Size: gtx.Constraints.Min}
@@ -129,82 +130,65 @@ func (t *Tracker) layoutInstrumentNames() layout.Widget {
 	}
 }
 func (t *Tracker) layoutInstrumentEditor() layout.Widget {
+	for t.AddUnitBtn.Clicked() {
+		t.AddUnit()
+	}
+	addUnitBtnStyle := material.IconButton(t.Theme, t.AddUnitBtn, widgetForIcon(icons.ContentAdd))
+	addUnitBtnStyle.Inset = layout.UniformInset(unit.Dp(4))
+	margin := layout.UniformInset(unit.Dp(2))
+
 	return func(gtx C) D {
-		paint.FillShape(gtx.Ops, instrumentSurfaceColor, clip.Rect{
-			Max: gtx.Constraints.Max,
-		}.Op())
 		return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
-			layout.Rigid(t.layoutUnitList()),
-			layout.Rigid(t.layoutUnitControls()))
+			layout.Rigid(func(gtx C) D {
+				return layout.Stack{Alignment: layout.SE}.Layout(gtx,
+					layout.Expanded(t.layoutUnitList()),
+					layout.Stacked(func(gtx C) D {
+						return margin.Layout(gtx, addUnitBtnStyle.Layout)
+					}))
+			}),
+			layout.Rigid(t.layoutUnitEditor()))
 	}
 }
 
 func (t *Tracker) layoutUnitList() layout.Widget {
 	return func(gtx C) D {
+		paint.FillShape(gtx.Ops, unitListSurfaceColor, clip.Rect{Max: image.Pt(gtx.Constraints.Max.X, gtx.Constraints.Max.Y)}.Op())
+		defer op.Save(gtx.Ops).Load()
+
+		gtx.Constraints.Min.Y = gtx.Constraints.Max.Y
 		units := t.song.Patch.Instruments[t.CurrentInstrument].Units
 		count := len(units)
-		if len(t.UnitBtns) < count {
-			tail := make([]*widget.Clickable, count-len(t.UnitBtns))
-			for t := range tail {
-				tail[t] = new(widget.Clickable)
-			}
-			t.UnitBtns = append(t.UnitBtns, tail...)
+		for len(t.UnitBtns) < count {
+			t.UnitBtns = append(t.UnitBtns, new(widget.Clickable))
 		}
-		children := make([]layout.FlexChild, len(t.song.Patch.Instruments[t.CurrentInstrument].Units))
-		for i, u := range t.song.Patch.Instruments[t.CurrentInstrument].Units {
+
+		listElem := func(gtx C, i int) D {
 			for t.UnitBtns[i].Clicked() {
 				t.CurrentUnit = i
+				op.InvalidateOp{}.Add(gtx.Ops)
 			}
-			i2 := i
+			u := t.song.Patch.Instruments[t.CurrentInstrument].Units[i]
 			labelStyle := LabelStyle{Text: u.Type, ShadeColor: black, Color: white, Font: labelDefaultFont, FontSize: unit.Sp(12)}
-			children[i] = layout.Rigid(func(gtx C) D {
-				dims := labelStyle.Layout(gtx)
-				gtx.Constraints = layout.Exact(dims.Size)
-				t.UnitBtns[i2].Layout(gtx)
-				return dims
-			})
+			if labelStyle.Text == "" {
+				labelStyle.Text = "---"
+				labelStyle.Alignment = layout.Center
+			}
+			bg := func(gtx C) D {
+				gtx.Constraints = layout.Exact(image.Pt(120, 20))
+				var color color.NRGBA
+				if t.CurrentUnit == i {
+					color = unitListSelectedColor
+				} else if t.UnitBtns[i].Hovered() {
+					color = unitListHighlightColor
+				}
+				paint.FillShape(gtx.Ops, color, clip.Rect{Max: image.Pt(gtx.Constraints.Min.X, gtx.Constraints.Min.Y)}.Op())
+				return D{Size: gtx.Constraints.Min}
+			}
+			return layout.Stack{Alignment: layout.W}.Layout(gtx,
+				layout.Stacked(bg),
+				layout.Expanded(labelStyle.Layout),
+				layout.Expanded(t.UnitBtns[i].Layout))
 		}
-		return layout.Flex{Axis: layout.Vertical}.Layout(gtx, children...)
-	}
-}
-
-func (t *Tracker) layoutUnitControls() layout.Widget {
-	return func(gtx C) D {
-		params := t.song.Patch.Instruments[t.CurrentInstrument].Units[t.CurrentUnit].Parameters
-		count := len(params)
-		children := make([]layout.FlexChild, 0, count)
-		if len(t.ParameterSliders) < count {
-			tail := make([]*widget.Float, count-len(t.ParameterSliders))
-			for t := range tail {
-				tail[t] = new(widget.Float)
-			}
-			t.ParameterSliders = append(t.ParameterSliders, tail...)
-		}
-		keys := make([]string, 0, len(params))
-		for k := range params {
-			keys = append(keys, k)
-		}
-		sort.Strings(keys)
-		for i, k := range keys {
-			for t.ParameterSliders[i].Changed() {
-				params[k] = int(t.ParameterSliders[i].Value)
-				// TODO: tracker should have functions to update parameters and
-				// to do this efficiently i.e. not compile the whole patch again
-				t.LoadSong(t.song)
-			}
-			t.ParameterSliders[i].Value = float32(params[k])
-			sliderStyle := material.Slider(t.Theme, t.ParameterSliders[i], 0, 128)
-			sliderStyle.Color = t.Theme.Fg
-			k2 := k // avoid k changing in the closure
-			children = append(children, layout.Rigid(func(gtx C) D {
-				return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
-					layout.Rigid(Label(k2, white)),
-					layout.Rigid(func(gtx C) D {
-						gtx.Constraints.Min.X = 200
-						return sliderStyle.Layout(gtx)
-					}))
-			}))
-		}
-		return layout.Flex{Axis: layout.Vertical}.Layout(gtx, children...)
+		return t.UnitList.Layout(gtx, len(t.song.Patch.Instruments[t.CurrentInstrument].Units), listElem)
 	}
 }

tracker/label.go

@@ -17,12 +17,13 @@ type LabelStyle struct {
 	Text       string
 	Color      color.NRGBA
 	ShadeColor color.NRGBA
+	Alignment  layout.Direction
 	Font       text.Font
 	FontSize   unit.Value
 }
 
 func (l LabelStyle) Layout(gtx layout.Context) layout.Dimensions {
-	return layout.Stack{Alignment: layout.Center}.Layout(gtx,
+	return layout.Stack{Alignment: l.Alignment}.Layout(gtx,
 		layout.Stacked(func(gtx layout.Context) layout.Dimensions {
 			defer op.Save(gtx.Ops).Load()
 			paint.ColorOp{Color: l.ShadeColor}.Add(gtx.Ops)
@@ -46,6 +47,6 @@ func (l LabelStyle) Layout(gtx layout.Context) layout.Dimensions {
 	)
 }
 
-func Label(text string, color color.NRGBA) layout.Widget {
-	return LabelStyle{Text: text, Color: color, ShadeColor: black, Font: labelDefaultFont, FontSize: labelDefaultFontSize}.Layout
+func Label(str string, color color.NRGBA) layout.Widget {
+	return LabelStyle{Text: str, Color: color, ShadeColor: black, Font: labelDefaultFont, FontSize: labelDefaultFontSize, Alignment: layout.W}.Layout
 }

tracker/popup.go

@@ -56,6 +56,7 @@ func (s PopupStyle) Layout(gtx C, contents layout.Widget) D {
 	}
 
 	bg := func(gtx C) D {
+		pointer.PassOp{Pass: true}.Add(gtx.Ops)
 		pointer.InputOp{Tag: s.Visible,
 			Types: pointer.Press,
 		}.Add(gtx.Ops)

tracker/theme.go

@@ -85,9 +85,16 @@ var patternSelectionColor = color.NRGBA{R: 19, G: 40, B: 60, A: 128}
 
 var inactiveBtnColor = color.NRGBA{R: 61, G: 55, B: 55, A: 255}
 
-var instrumentSurfaceColor = color.NRGBA{R: 37, G: 37, B: 38, A: 255}
+var instrumentSurfaceColor = color.NRGBA{R: 45, G: 45, B: 45, A: 255}
 
 var songSurfaceColor = color.NRGBA{R: 37, G: 37, B: 38, A: 255}
 
-var popupSurfaceColor = color.NRGBA{R: 45, G: 45, B: 46, A: 255}
+var popupSurfaceColor = color.NRGBA{R: 50, G: 50, B: 51, A: 255}
 var popupShadowColor = color.NRGBA{R: 0, G: 0, B: 0, A: 192}
+
+var unitListSurfaceColor = color.NRGBA{R: 37, G: 37, B: 38, A: 255}
+var unitListSelectedColor = color.NRGBA{R: 55, G: 55, B: 61, A: 255}
+var unitListHighlightColor = color.NRGBA{R: 42, G: 45, B: 61, A: 255}
+
+var unitSurfaceColor = color.NRGBA{R: 30, G: 30, B: 30, A: 255}
+var unitTypeListHighlightColor = color.NRGBA{R: 42, G: 45, B: 61, A: 255}

tracker/tracker.go

@@ -25,6 +25,9 @@ type Tracker struct {
 	CursorColumn          int
 	CurrentInstrument     int
 	CurrentUnit           int
+	UnitGroupMenuVisible  bool
+	UnitGroupMenuIndex    int
+	UnitSubMenuIndex      int
 	NoteTracking          bool
 	Theme                 *material.Theme
 	Octave                *NumberInput
@@ -47,7 +50,13 @@ type Tracker struct {
 	FileMenuVisible       bool
 	ParameterSliders      []*widget.Float
 	UnitBtns              []*widget.Clickable
+	UnitList              *layout.List
+	DeleteUnitBtn         *widget.Clickable
+	ClearUnitBtn          *widget.Clickable
+	ChooseUnitTypeList    *layout.List
+	ChooseUnitTypeBtns    []*widget.Clickable
 	InstrumentBtns        []*widget.Clickable
+	AddUnitBtn            *widget.Clickable
 	InstrumentList        *layout.List
 	TrackHexCheckBoxes    []*widget.Bool
 	TrackShowHex          []bool
@@ -329,6 +338,51 @@ func (t *Tracker) SetRowsPerPattern(value int) {
 	}
 }
 
+func (t *Tracker) SetUnit(typ string) {
+	unit, ok := defaultUnits[typ]
+	if !ok {
+		return
+	}
+	if unit.Type == t.song.Patch.Instruments[t.CurrentInstrument].Units[t.CurrentUnit].Type {
+		return
+	}
+	t.SaveUndo()
+	t.song.Patch.Instruments[t.CurrentInstrument].Units[t.CurrentUnit] = unit.Copy()
+	t.sequencer.SetPatch(t.song.Patch)
+}
+
+func (t *Tracker) AddUnit() {
+	t.SaveUndo()
+	units := make([]sointu.Unit, len(t.song.Patch.Instruments[t.CurrentInstrument].Units)+1)
+	copy(units, t.song.Patch.Instruments[t.CurrentInstrument].Units[:t.CurrentUnit+1])
+	copy(units[t.CurrentUnit+2:], t.song.Patch.Instruments[t.CurrentInstrument].Units[t.CurrentUnit+1:])
+	t.song.Patch.Instruments[t.CurrentInstrument].Units = units
+	t.CurrentUnit++
+	t.sequencer.SetPatch(t.song.Patch)
+}
+
+func (t *Tracker) ClearUnit() {
+	t.SaveUndo()
+	t.song.Patch.Instruments[t.CurrentInstrument].Units[t.CurrentUnit].Type = ""
+	t.song.Patch.Instruments[t.CurrentInstrument].Units[t.CurrentUnit].Parameters = make(map[string]int)
+	t.sequencer.SetPatch(t.song.Patch)
+}
+
+func (t *Tracker) DeleteUnit() {
+	if len(t.song.Patch.Instruments[t.CurrentInstrument].Units) <= 1 {
+		return
+	}
+	t.SaveUndo()
+	units := make([]sointu.Unit, len(t.song.Patch.Instruments[t.CurrentInstrument].Units)-1)
+	copy(units, t.song.Patch.Instruments[t.CurrentInstrument].Units[:t.CurrentUnit])
+	copy(units[t.CurrentUnit:], t.song.Patch.Instruments[t.CurrentInstrument].Units[t.CurrentUnit+1:])
+	t.song.Patch.Instruments[t.CurrentInstrument].Units = units
+	if t.CurrentUnit > 0 {
+		t.CurrentUnit--
+	}
+	t.sequencer.SetPatch(t.song.Patch)
+}
+
 func (t *Tracker) ClampPositions() {
 	t.PlayPosition.Clamp(t.song)
 	t.Cursor.Clamp(t.song)
@@ -416,6 +470,10 @@ func New(audioContext sointu.AudioContext) *Tracker {
 		SubtractSemitoneBtn:   new(widget.Clickable),
 		AddOctaveBtn:          new(widget.Clickable),
 		SubtractOctaveBtn:     new(widget.Clickable),
+		AddUnitBtn:            new(widget.Clickable),
+		DeleteUnitBtn:         new(widget.Clickable),
+		ClearUnitBtn:          new(widget.Clickable),
+		UnitList:              &layout.List{Axis: layout.Vertical},
 		setPlaying:            make(chan bool),
 		rowJump:               make(chan int),
 		patternJump:           make(chan int),
@@ -427,12 +485,16 @@ func New(audioContext sointu.AudioContext) *Tracker {
 		TopHorizontalSplit:    new(Split),
 		BottomHorizontalSplit: new(Split),
 		VerticalSplit:         new(Split),
+		ChooseUnitTypeList:    &layout.List{Axis: layout.Vertical},
 	}
 	t.Octave.Value = 4
 	t.VerticalSplit.Axis = layout.Vertical
 	t.BottomHorizontalSplit.Ratio = -.5
 	t.Theme.Palette.Fg = primaryColor
 	t.Theme.Palette.ContrastFg = black
+	for range allUnits {
+		t.ChooseUnitTypeBtns = append(t.ChooseUnitTypeBtns, new(widget.Clickable))
+	}
 	go t.sequencerLoop(t.closer)
 	if err := t.LoadSong(defaultSong.Copy()); err != nil {
 		panic(fmt.Errorf("cannot load default song: %w", err))

tracker/uniteditor.go

@@ -0,0 +1,132 @@
+package tracker
+
+import (
+	"image"
+	"image/color"
+	"sort"
+
+	"gioui.org/layout"
+	"gioui.org/op"
+	"gioui.org/op/clip"
+	"gioui.org/op/paint"
+	"gioui.org/unit"
+	"gioui.org/widget"
+	"gioui.org/widget/material"
+	"golang.org/x/exp/shiny/materialdesign/icons"
+)
+
+func (t *Tracker) layoutUnitEditor() layout.Widget {
+	editorFunc := t.layoutUnitSliders
+	if t.song.Patch.Instruments[t.CurrentInstrument].Units[t.CurrentUnit].Type == "" {
+		editorFunc = t.layoutUnitTypeChooser
+	}
+	return func(gtx C) D {
+		paint.FillShape(gtx.Ops, unitSurfaceColor, clip.Rect{Max: image.Pt(gtx.Constraints.Max.X, gtx.Constraints.Max.Y)}.Op())
+		return layout.Flex{Axis: layout.Vertical}.Layout(gtx,
+			layout.Flexed(1, editorFunc()),
+			layout.Rigid(t.layoutUnitFooter()),
+		)
+	}
+}
+
+func (t *Tracker) layoutUnitSliders() layout.Widget {
+	return func(gtx C) D {
+		params := t.song.Patch.Instruments[t.CurrentInstrument].Units[t.CurrentUnit].Parameters
+		count := len(params)
+		children := make([]layout.FlexChild, 0, count)
+		if len(t.ParameterSliders) < count {
+			tail := make([]*widget.Float, count-len(t.ParameterSliders))
+			for t := range tail {
+				tail[t] = new(widget.Float)
+			}
+			t.ParameterSliders = append(t.ParameterSliders, tail...)
+		}
+		keys := make([]string, 0, len(params))
+		for k := range params {
+			keys = append(keys, k)
+		}
+		sort.Strings(keys)
+		for i, k := range keys {
+			for t.ParameterSliders[i].Changed() {
+				params[k] = int(t.ParameterSliders[i].Value)
+				// TODO: tracker should have functions to update parameters and
+				// to do this efficiently i.e. not compile the whole patch again
+				t.LoadSong(t.song)
+			}
+			t.ParameterSliders[i].Value = float32(params[k])
+			sliderStyle := material.Slider(t.Theme, t.ParameterSliders[i], 0, 128)
+			sliderStyle.Color = t.Theme.Fg
+			k2 := k // avoid k changing in the closure
+			children = append(children, layout.Rigid(func(gtx C) D {
+				return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
+					layout.Rigid(Label(k2, white)),
+					layout.Rigid(func(gtx C) D {
+						gtx.Constraints.Min.X = 200
+						return sliderStyle.Layout(gtx)
+					}))
+			}))
+		}
+		return layout.Flex{Axis: layout.Vertical}.Layout(gtx, children...)
+	}
+}
+
+func (t *Tracker) layoutUnitFooter() layout.Widget {
+	return func(gtx C) D {
+		for t.ClearUnitBtn.Clicked() {
+			t.ClearUnit()
+			op.InvalidateOp{}.Add(gtx.Ops)
+		}
+		for t.DeleteUnitBtn.Clicked() {
+			t.DeleteUnit()
+			op.InvalidateOp{}.Add(gtx.Ops)
+		}
+		deleteUnitBtnStyle := material.IconButton(t.Theme, t.DeleteUnitBtn, widgetForIcon(icons.ActionDelete))
+		deleteUnitBtnStyle.Background = transparent
+		deleteUnitBtnStyle.Inset = layout.UniformInset(unit.Dp(6))
+		if len(t.song.Patch.Instruments[t.CurrentInstrument].Units) > 1 {
+			deleteUnitBtnStyle.Color = primaryColor
+		} else {
+			deleteUnitBtnStyle.Color = disabledTextColor
+		}
+		if t.song.Patch.Instruments[t.CurrentInstrument].Units[t.CurrentUnit].Type == "" {
+			return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
+				layout.Flexed(1, func(gtx C) D { return layout.Dimensions{Size: gtx.Constraints.Min} }),
+				layout.Rigid(deleteUnitBtnStyle.Layout))
+		}
+		clearUnitBtnStyle := material.IconButton(t.Theme, t.ClearUnitBtn, widgetForIcon(icons.ContentClear))
+		clearUnitBtnStyle.Color = primaryColor
+		clearUnitBtnStyle.Background = transparent
+		clearUnitBtnStyle.Inset = layout.UniformInset(unit.Dp(6))
+		return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
+			layout.Flexed(1, func(gtx C) D { return layout.Dimensions{Size: gtx.Constraints.Min} }),
+			layout.Rigid(clearUnitBtnStyle.Layout),
+			layout.Rigid(deleteUnitBtnStyle.Layout))
+	}
+}
+
+func (t *Tracker) layoutUnitTypeChooser() layout.Widget {
+	return func(gtx C) D {
+		paint.FillShape(gtx.Ops, unitSurfaceColor, clip.Rect{Max: image.Pt(gtx.Constraints.Max.X, gtx.Constraints.Max.Y)}.Op())
+		listElem := func(gtx C, i int) D {
+			for t.ChooseUnitTypeBtns[i].Clicked() {
+				u := defaultUnits[allUnits[i]]
+				t.song.Patch.Instruments[t.CurrentInstrument].Units[t.CurrentUnit] = (&u).Copy()
+			}
+			labelStyle := LabelStyle{Text: allUnits[i], ShadeColor: black, Color: white, Font: labelDefaultFont, FontSize: unit.Sp(12)}
+			bg := func(gtx C) D {
+				gtx.Constraints = layout.Exact(image.Pt(120, 20))
+				var color color.NRGBA
+				if t.ChooseUnitTypeBtns[i].Hovered() {
+					color = unitTypeListHighlightColor
+				}
+				paint.FillShape(gtx.Ops, color, clip.Rect{Max: image.Pt(gtx.Constraints.Min.X, gtx.Constraints.Min.Y)}.Op())
+				return D{Size: gtx.Constraints.Min}
+			}
+			return layout.Stack{Alignment: layout.W}.Layout(gtx,
+				layout.Stacked(bg),
+				layout.Expanded(labelStyle.Layout),
+				layout.Expanded(t.ChooseUnitTypeBtns[i].Layout))
+		}
+		return t.ChooseUnitTypeList.Layout(gtx, len(allUnits), listElem)
+	}
+}