The piano plays sound

examples/piano/main.go

@@ -1,12 +1,23 @@
 package main
 
+import "github.com/faiface/beep"
+import "github.com/faiface/beep/speaker"
+import "github.com/faiface/beep/generators"
 import "git.tebibyte.media/sashakoshka/tomo"
-import "git.tebibyte.media/sashakoshka/tomo/layouts/basic"
 import "git.tebibyte.media/sashakoshka/tomo/elements/fun"
+import "git.tebibyte.media/sashakoshka/tomo/layouts/basic"
 import "git.tebibyte.media/sashakoshka/tomo/elements/basic"
+import "git.tebibyte.media/sashakoshka/tomo/elements/fun/music"
 import _ "git.tebibyte.media/sashakoshka/tomo/backends/x"
 
+const sampleRate = 44100
+const bufferSize = 256
+var   tuning     = music.EqualTemparment { A4: 440 }
+
+var playing = map[music.Note] *beep.Ctrl { }
+
 func main () {
+	speaker.Init(sampleRate, bufferSize)
 	tomo.Run(run)
 }
 
@@ -20,7 +31,29 @@ func run () {
 	container.Adopt(label, false)
 	piano := fun.NewPiano(3, 5)
 	container.Adopt(piano, true)
+	piano.OnPress(playNote)
+	piano.OnRelease(stopNote)
 	
 	window.OnClose(tomo.Stop)
 	window.Show()
 }
+
+func stopNote (note music.Note) {
+	if _, is := playing[note]; !is { return }
+	
+	speaker.Lock() 
+	playing[note].Streamer = nil
+	delete(playing, note)
+	speaker.Unlock()
+}
+
+func playNote (note music.Note) {
+	streamer, err := generators.SinTone(sampleRate, int(tuning.Tune(note)))
+	if err != nil { panic(err.Error()) }
+
+	stopNote(note)
+	speaker.Lock()
+	playing[note] = &beep.Ctrl { Streamer: streamer }
+	speaker.Unlock()
+	speaker.Play(playing[note])
+}