Piano keyboard

In plain words

A keyboard you can play with the mouse: click a key to play a note, drag across the keys to slide from one to the next. Notes played from elsewhere (a MIDI keyboard, a sequencer) light up.

from pyzed import audio, ui

engine = audio.Engine()
synth = engine.add("midi_in")  # notes from note_on/note_off reach the midi_in modules
...

ui.audio.Piano(start=48, octaves=3, pressed=sorted(self.held),
               on_note_on=lambda e: engine.note_on(e.value.note, e.value.velocity),
               on_note_off=lambda e: engine.note_off(e.value))

Notes and velocity

Notes are MIDI numbers: 60 is middle C (C4), 69 is the A at 440 Hz. note_on gives a Note(note, velocity); the lower on a key you click, the louder (velocity 30 to 127). note_off gives the note number. Dragging across keys releases one and presses the next.

ui.audio.note_name(61) gives "C#4", handy for labels.

Playing from the computer keyboard

ui.audio.KEYBOARD maps keys to semitones like most music apps: the row a s d f g h j k is the white keys and w e t y u o p the black ones.

def on_key(self, combo):
    if combo in ui.audio.KEYBOARD and combo not in self.keys:
        self.keys.add(combo)
        note = self.octave * 12 + ui.audio.KEYBOARD[combo]
        engine.note_on(note)

def on_key_up(self, key):
    if key in self.keys:
        self.keys.discard(key)
        engine.note_off(self.octave * 12 + ui.audio.KEYBOARD[key])

Property	Default	What it does
start	48	The first note (rounded down to a C).
octaves	2	How many octaves (plus the last C).
pressed	()	Notes to light, played from elsewhere.
color	"accent"	Color of pressed keys.
key_width, height	24, 110	Size of a white key.
labels	True	Writes the name of every C.

Events: on_note_on (Note(note, velocity)), on_note_off (the note number).