A midi plugin for a 3x3 pad.

midipad.py

from rtmidi.midiutil import open_midiport

NOTEON = 144
NOTEOFF = 128
BASE = 65
SCALE = [1, 2, 1, 1, 2, 2, 1, 2]
NOTE = BASE
STEP = 0

TOPBASE = BASE + 24

P1, P2, P3, P4, P5, P6, P7, P8, P9 = [60, 62, 64, 65, 67, 69, 71, 72, 74]


def move_up_in_scale():
    global STEP, NOTE
    NOTE += SCALE[STEP]
    STEP += 1
    if STEP > len(SCALE) - 1:
        STEP = 0


def move_down_in_scale():
    global STEP, NOTE
    NOTE -= SCALE[STEP]        
    STEP -= 1
    if STEP < 0:
        STEP = len(SCALE) - 1


def ping(event, data=None):
    global NOTE, STEP
    etype, note, value = event[0]
    if etype == NOTEON:
        print "Received NOTEON for:", note, value
        if note == P1:
            move_down_in_scale()
        elif note == P2:
            NOTE = TOPBASE
            STEP = 0
        elif note == P3:
            move_up_in_scale()
        elif note == P4:
            move_down_in_scale()
            move_down_in_scale()
        elif note == P5:
            pass
        elif note == P6:
            move_up_in_scale()
            move_up_in_scale()
        elif note == P7:
            move_down_in_scale()
            move_down_in_scale()
            move_down_in_scale()
        elif note == P8:
            NOTE = BASE
            STEP = 0
        elif note == P9:
            move_up_in_scale()
            move_up_in_scale()
            move_up_in_scale()
        else:
            print "Unknown PAD", note
            
        midiout.send_message([NOTEON, NOTE, value])

midiout, outport_name = open_midiport(type_="output", use_virtual=True)
midiin, inport_name = open_midiport(type_="input", use_virtual=True)

midiin.set_callback(ping)

while True:
    pass