The piano plays sound

elements/fun/music/music.go

@@ -0,0 +1,69 @@
+package music
+
+import "math"
+
+var semitone = math.Pow(2, 1.0 / 12.0)
+
+// Tuning is an interface representing a tuning.
+type Tuning interface {
+	// Tune returns the frequency of a given note in Hz.
+	Tune (Note) float64
+}
+
+// EqualTemparment implements twelve-tone equal temparment.
+type EqualTemparment struct { A4 float64 }
+
+// Tune returns the EqualTemparment frequency of a given note in Hz.
+func (tuning EqualTemparment) Tune (note Note) float64 {
+	return tuning.A4 * math.Pow(semitone, float64(note - NoteA4))
+}
+
+// Octave represents a MIDI octave.
+type Octave int
+
+// Note returns the note at the specified scale degree in the chromatic scale.
+func (octave Octave) Note (degree int) Note {
+	return Note(int(octave + 1) * 12 + degree)
+}
+
+// Note represents a MIDI note.
+type Note int
+
+const (
+	NoteC0 Note = iota
+	NoteDb0
+	NoteD0
+	NoteEb0
+	NoteE0
+	NoteF0
+	NoteGb0
+	NoteG0
+	NoteAb0
+	NoteA0
+	NoteBb0
+	NoteB0
+
+	NoteA4 Note = 69
+)
+
+// Octave returns the octave of the note
+func (note Note) Octave () int {
+	return int(note / 12 - 1)
+}
+
+// Degree returns the scale degree of the note in the chromatic scale.
+func (note Note) Degree () int {
+	mod := note % 12
+	if mod < 0 { mod += 12 }
+	return int(mod)
+}
+
+// IsSharp returns whether or not the note is a sharp.
+func (note Note) IsSharp () bool {
+	degree := note.Degree()
+	return degree == 1 ||
+		degree == 3 ||
+		degree == 6 ||
+		degree == 8 ||
+		degree == 10
+}

elements/fun/piano.go

@@ -6,51 +6,19 @@ import "git.tebibyte.media/sashakoshka/tomo/theme"
 import "git.tebibyte.media/sashakoshka/tomo/config"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
 import "git.tebibyte.media/sashakoshka/tomo/elements/core"
-
-// Octave represents a MIDI octave.
-type Octave int
-
-// Note returns the note at the specified scale degree in the chromatic scale.
-func (octave Octave) Note (degree int) Note {
-	return Note(int(octave + 1) * 12 + degree)
-}
-
-// Note represents a MIDI note.
-type Note int
-
-// Octave returns the octave of the note
-func (note Note) Octave () int {
-	return int(note / 12 - 1)
-}
-
-// Degree returns the scale degree of the note in the chromatic scale.
-func (note Note) Degree () int {
-	mod := note % 12
-	if mod < 0 { mod += 12 }
-	return int(mod)
-}
-
-// IsSharp returns whether or not the note is a sharp.
-func (note Note) IsSharp () bool {
-	degree := note.Degree()
-	return degree == 1 ||
-		degree == 3 ||
-		degree == 6 ||
-		degree == 8 ||
-		degree == 10
-}
+import "git.tebibyte.media/sashakoshka/tomo/elements/fun/music"
 
 const pianoKeyWidth = 18
 
 type pianoKey struct {
 	image.Rectangle
-	Note
+	music.Note
 }
 
 type Piano struct {
 	*core.Core
 	core core.CoreControl
-	low, high Octave
+	low, high music.Octave
 	
 	config config.Wrapped
 	theme  theme.Wrapped
@@ -60,11 +28,11 @@ type Piano struct {
 
 	pressed *pianoKey
 
-	onPress   func (Note)
-	onRelease func (Note)
+	onPress   func (music.Note)
+	onRelease func (music.Note)
 }
 
-func NewPiano (low, high Octave) (element *Piano) {
+func NewPiano (low, high music.Octave) (element *Piano) {
 	element = &Piano {
 		low:  low,
 		high: high,
@@ -79,12 +47,12 @@ func NewPiano (low, high Octave) (element *Piano) {
 }
 
 // OnPress sets a function to be called when a key is pressed.
-func (element *Piano) OnPress (callback func (note Note)) {
+func (element *Piano) OnPress (callback func (note music.Note)) {
 	element.onPress = callback
 }
 
 // OnRelease sets a function to be called when a key is released.
-func (element *Piano) OnRelease (callback func (note Note)) {
+func (element *Piano) OnRelease (callback func (note music.Note)) {
 	element.onRelease = callback
 }
 
@@ -110,11 +78,6 @@ func (element *Piano) HandleMouseMove (x, y int) {
 func (element *Piano) HandleMouseScroll (x, y int, deltaX, deltaY float64) { }
 
 func (element *Piano) pressUnderMouseCursor (point image.Point) {
-	// release previous note
-	if element.pressed != nil && element.onRelease != nil {
-		element.onRelease((*element.pressed).Note)
-	}
-
 	// find out which note is being pressed
 	newKey := (*pianoKey)(nil)
 	for index, key := range element.flatKeys {
@@ -132,6 +95,11 @@ func (element *Piano) pressUnderMouseCursor (point image.Point) {
 	if newKey == nil { return }
 	
 	if newKey != element.pressed {
+		// release previous note
+		if element.pressed != nil && element.onRelease != nil {
+			element.onRelease((*element.pressed).Note)
+		}
+	
 		// press new note
 		element.pressed = newKey
 		if element.onPress != nil {
@@ -198,7 +166,7 @@ func (element *Piano) recalculate () {
 			element.sharpKeys[sharpIndex].Rectangle = image.Rect (
 				-(pianoKeyWidth * 3) / 7, 0,
 				(pianoKeyWidth * 3) / 7,
-				bounds.Dy() / 2).Add(dot)
+				(bounds.Dy() * 5) / 8).Add(dot)
 			element.sharpKeys[sharpIndex].Note = note
 			sharpIndex ++
 		} else {