thread safety for event loop and redraw loop

screen.go

@@ -11,7 +11,11 @@ import (
 type Screen struct {
 	scr tcell.Screen
 	buf *ViewBuffer
+
 	stopCh   chan error
+	redrawCh chan struct{}
+
+	// Root is the root view which is currently shown on screen
 	Root View
 
 	// KeyPressed is called every time a key or key-combination is pressed.
@@ -31,29 +35,15 @@ func NewScreen(root View) (*Screen, error) {
 		Root:     root,
 		scr:      scr,
 		stopCh:   make(chan error, 1),
+		redrawCh: make(chan struct{}, 1),
 	}
 
 	go s.eventloop()
+	go s.drawloop()
 
 	return s, nil
 }
 
-func (s *Screen) eventloop() {
-	for evt := s.scr.PollEvent(); evt != nil; evt = s.scr.PollEvent() {
-		switch event := evt.(type) {
-		case *tcell.EventResize:
-			go s.Redraw()
-		case *tcell.EventKey:
-			go s.onKeyPressed(event)
-		case *tcell.EventMouse:
-			go s.onMouseClicked(convertMouseEvent(event))
-		default:
-			s.StopWithError(errors.New(fmt.Sprintf("%#v", event)))
-		}
-	}
-	s.StopWithError(errors.New("unknown error occured"))
-}
-
 func (s *Screen) Start() error {
 	err := s.scr.Init()
 	if err != nil {
@@ -99,6 +89,31 @@ func convertMouseEvent(original *tcell.EventMouse) *MouseEvent {
 }
 
 func (s *Screen) Redraw() {
+	s.redrawCh <- struct{}{}
+}
+
+func (s *Screen) eventloop() {
+	defer s.stopOnPanic()
+
+	for evt := s.scr.PollEvent(); evt != nil; evt = s.scr.PollEvent() {
+		switch event := evt.(type) {
+		case *tcell.EventResize:
+			go s.Redraw()
+		case *tcell.EventKey:
+			go s.onKeyPressed(event)
+		case *tcell.EventMouse:
+			go s.onMouseClicked(convertMouseEvent(event))
+		default:
+			s.StopWithError(errors.New(fmt.Sprintf("%#v", event)))
+		}
+	}
+	s.StopWithError(errors.New("unknown error occured"))
+}
+
+func (s *Screen) drawloop() {
+	defer s.stopOnPanic()
+
+	for range s.redrawCh {
 		w, h := s.scr.Size()
 
 		if s.buf == nil || s.buf.Width() != w || s.buf.Height() != h {
@@ -109,3 +124,10 @@ func (s *Screen) Redraw() {
 		s.Root.Draw(truncateBuffer(s.buf, rw, rh))
 		drawBuffer(s.scr, s.buf)
 	}
+}
+
+func (s *Screen) stopOnPanic() {
+	if err := recover(); err != nil {
+		s.StopWithError(fmt.Errorf("%v", err))
+	}
+}