feat(tracker): add panic button to quickly disable the sound & show when synth crashes

tracker/sequencer.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"math"
 	"sync"
+	"sync/atomic"
 
 	"github.com/vsariola/sointu"
 )
@@ -21,9 +22,10 @@ const SEQUENCER_MAX_READ_TRIES = 1000
 type Sequencer struct {
 	// we use mutex to ensure that voices are not triggered during readaudio or
 	// that the synth is not changed when audio is being read
-	mutex   sync.Mutex
-	synth   sointu.Synth
-	service sointu.SynthService
+	mutex      sync.Mutex
+	synth      sointu.Synth
+	validSynth int32
+	service    sointu.SynthService
 	// this iterator is a bit unconventional in the sense that it might return
 	// hasNext false, but might still return hasNext true in future attempts if
 	// new rows become available.
@@ -72,10 +74,10 @@ func (s *Sequencer) ReadAudio(buffer []float32) (int, error) {
 		if !gotRow {
 			rowTimeRemaining = math.MaxInt32
 		}
-		if s.synth != nil {
+		if s.Enabled() {
 			rendered, timeAdvanced, err := s.synth.Render(buffer[totalRendered*2:], rowTimeRemaining)
 			if err != nil {
-				s.synth = nil
+				s.Disable()
 			}
 			totalRendered += rendered
 			s.rowTime += timeAdvanced
@@ -98,14 +100,26 @@ func (s *Sequencer) ReadAudio(buffer []float32) (int, error) {
 // Updates the patch of the synth
 func (s *Sequencer) SetPatch(patch sointu.Patch) {
 	s.mutex.Lock()
-	if s.synth != nil {
-		s.synth.Update(patch)
+	var err error
+	if s.Enabled() {
+		err = s.synth.Update(patch)
 	} else {
-		s.synth, _ = s.service.Compile(patch)
+		s.synth, err = s.service.Compile(patch)
+	}
+	if err == nil {
+		atomic.StoreInt32(&s.validSynth, 1)
 	}
 	s.mutex.Unlock()
 }
 
+func (s *Sequencer) Enabled() bool {
+	return atomic.LoadInt32(&s.validSynth) == 1
+}
+
+func (s *Sequencer) Disable() {
+	atomic.StoreInt32(&s.validSynth, 0)
+}
+
 func (s *Sequencer) SetRowLength(rowLength int) {
 	s.mutex.Lock()
 	s.rowLength = rowLength

tracker/songpanel.go

@@ -17,7 +17,7 @@ import (
 func (t *Tracker) layoutSongPanel(gtx C) D {
 	return layout.Flex{Axis: layout.Vertical}.Layout(gtx,
 		layout.Rigid(t.layoutSongButtons),
-		layout.Flexed(1, t.layoutSongOptions),
+		layout.Rigid(t.layoutSongOptions),
 	)
 }
 
@@ -100,6 +100,23 @@ func (t *Tracker) layoutSongOptions(gtx C) D {
 
 	in := layout.UniformInset(unit.Dp(1))
 
+	panicBtnStyle := material.Button(t.Theme, t.PanicBtn, "Panic")
+	if t.sequencer.Enabled() {
+		panicBtnStyle.Background = transparent
+		panicBtnStyle.Color = t.Theme.Palette.Fg
+	} else {
+		panicBtnStyle.Background = t.Theme.Palette.Fg
+		panicBtnStyle.Color = t.Theme.Palette.ContrastFg
+	}
+
+	for t.PanicBtn.Clicked() {
+		if t.sequencer.Enabled() {
+			t.sequencer.Disable()
+		} else {
+			t.sequencer.SetPatch(t.song.Patch)
+		}
+	}
+
 	return layout.Flex{Axis: layout.Vertical}.Layout(gtx,
 		layout.Rigid(func(gtx C) D {
 			return layout.Flex{Axis: layout.Horizontal}.Layout(gtx,
@@ -158,5 +175,9 @@ func (t *Tracker) layoutSongOptions(gtx C) D {
 				}),
 			)
 		}),
+		layout.Rigid(func(gtx C) D {
+			gtx.Constraints.Min = image.Pt(0, 0)
+			return panicBtnStyle.Layout(gtx)
+		}),
 	)
 }

tracker/tracker.go

@@ -60,6 +60,7 @@ type Tracker struct {
 	SongLength            *NumberInput
 	SaveSongFileBtn       *widget.Clickable
 	FileMenuBtn           *widget.Clickable
+	PanicBtn              *widget.Clickable
 	FileMenuVisible       bool
 	ParameterSliders      []*widget.Float
 	ParameterList         *layout.List
@@ -550,6 +551,7 @@ func New(audioContext sointu.AudioContext, synthService sointu.SynthService) *Tr
 		AddUnitBtn:            new(widget.Clickable),
 		DeleteUnitBtn:         new(widget.Clickable),
 		ClearUnitBtn:          new(widget.Clickable),
+		PanicBtn:              new(widget.Clickable),
 		UnitDragList:          &DragList{List: &layout.List{Axis: layout.Vertical}},
 		setPlaying:            make(chan bool),
 		rowJump:               make(chan int),