huion-keys/huion_keys.py

#!/usr/bin/env python3
import os
import time

from _xdo_cffi import ffi, lib

CONFIG_FILE_PATH = os.path.expanduser('~/.config/huion_keys.conf')

TABLET_MODELS = {
    "Kamvas Pro (2019)": "256c:006e",
    "Q620M": "256c:006d",
}

BUTTON_BINDINGS = {}

def main():
    xdo = lib.xdo_new(ffi.NULL)
    if os.path.isfile(CONFIG_FILE_PATH):
        read_config(CONFIG_FILE_PATH)
    else:
        print("No config file found.")
        create_default_config(CONFIG_FILE_PATH)
        print("Created an example config file at " + CONFIG_FILE_PATH)
        return 1
    prev_button = None
    while True:
        hidraw_path = None
        # search for a known tablet device
        for device_name, device_id in TABLET_MODELS.items():
            hidraw_path = get_tablet_hidraw(device_id)
            if hidraw_path is not None:
                print("Found %s at %s" % (device_name, hidraw_path))
                break
        if hidraw_path is None:
            print("Could not find tablet hidraw device")
            time.sleep(2)
            continue
        try:
            hidraw = open(hidraw_path, 'rb')
        except PermissionError as e:
            print(e)
            print("Trying again in 5 seconds...")
            time.sleep(5)
            continue
        while True:
            try:
                btn = get_button_press(hidraw)
            except OSError as e:
                print("Lost connection with the tablet - searching for tablet...")
                time.sleep(3)
                break
            print("Got button %s" % (btn,))
            if btn == 3:
                print("Pressing ctrl")
                lib.xdo_send_keysequence_window_down(xdo, lib.CURRENTWINDOW, b'ctrl', 12000)
                get_button_release(hidraw)
                print("Releasing ctrl")
                lib.xdo_send_keysequence_window_up(xdo, lib.CURRENTWINDOW, b'ctrl', 12000)
            elif btn in BUTTON_BINDINGS:
                print("Sending %s" % (BUTTON_BINDINGS[btn],))
                lib.xdo_send_keysequence_window(
                    xdo, lib.CURRENTWINDOW, BUTTON_BINDINGS[btn], 1000)


def get_tablet_hidraw(device_id):
    """Finds the /dev/hidrawX file that belongs to the given device ID (in xxxx:xxxx format)."""
    # TODO: is this too fragile?
    hidraws = os.listdir('/sys/class/hidraw')
    for h in hidraws:
        device_path = os.readlink(os.path.join('/sys/class/hidraw', h, 'device'))
        if device_id.upper() in device_path:
            # need to confirm that there's "input" because there are two hidraw
            # files listed for the tablet, but only one of them carries the
            # mouse/keyboard input
            if os.path.exists(os.path.join('/sys/class/hidraw', h, 'device/input')):
                return os.path.join('/dev', os.path.basename(h))
    return None


def read_config(config_file):
    with open(config_file, 'r') as config:
        for line in config.readlines():
            # strip out any comment
            if line.find('#') > -1:
                line = line[:line.find('#')]
            if line.find('='):
                setting = line[:line.find('=')].strip()
                value = line[line.find('=')+1:].strip()
                if setting.isdigit():
                    # store button configs with their 1-indexed ID
                    BUTTON_BINDINGS[int(setting)] = value.encode('utf-8')
                elif setting == 'scroll_up':
                    BUTTON_BINDINGS['scroll_up'] = value.encode('utf-8')
                elif setting == 'scroll_down':
                    BUTTON_BINDINGS['scroll_down'] = value.encode('utf-8')
                elif setting == 'dial_cw':
                    BUTTON_BINDINGS['dial_cw'] = value.encode('utf-8')
                elif setting == 'dial_ccw':
                    BUTTON_BINDINGS['dial_ccw'] = value.encode('utf-8')
                elif setting == '':
                    continue # ignore empty line
                else:
                    print("[WARN] unrecognized setting '%s'" % (setting,))


def create_default_config(config_file):
    with open(config_file, 'w') as config:
        config.write("""
# use one line for each button you want to configure
# buttons that aren't in this file will be ignored by this program
# (but may be handled by another driver)
4=ctrl+s
5=ctrl+z
6=ctrl+shift+equal
7=ctrl+minus
# etc. up to the highest button number
16=Tab
scroll_up=bracketright
scroll_down=bracketleft
#Q620M Dial
dial_cw=6
dial_ccw=4
""")


BUTTON_BITS = {
    0x01: 1,
    0x02: 2,
    0x04: 3,
    0x08: 4,
    0x10: 5,
    0x20: 6,
    0x40: 7,
    0x80: 8,
}

SCROLL_STATE=None

def get_button_press(hidraw):
    global SCROLL_STATE
    while True:
        sequence = hidraw.read(12)
        # 0xf7 is what my Kamvas Pro 22 reads
        # another model seems to send 0x08
        # Q620M reads as 0xf9
        if sequence[0] != 0xf7 and sequence[0] != 0x08 and sequence[0] != 0xf9:
            pass
        if sequence[1] == 0xe0: # buttons
            # doesn't seem like the tablet will let you push two buttons at once
            if sequence[4] > 0:
                return BUTTON_BITS[sequence[4]]
            elif sequence[5] > 0:
                # right-side buttons are 8-15, so add 8
                return BUTTON_BITS[sequence[5]] + 8
            else:
                # must be button release (all zeros)
                continue
        elif sequence[1] == 0xf0: # scroll strip
            scroll_pos = sequence[5]
            if scroll_pos == 0:
                # reset scroll state after lifting finger off scroll strip
                SCROLL_STATE = None
            elif SCROLL_STATE is not None:
                # scroll strip is numbered from top to bottom so a greater new
                # value means they scrolled down
                if scroll_pos > SCROLL_STATE:
                    SCROLL_STATE = scroll_pos
                    return 'scroll_down'
                elif scroll_pos < SCROLL_STATE:
                    SCROLL_STATE = scroll_pos
                    return 'scroll_up'
            else:
                SCROLL_STATE = scroll_pos
                continue
        elif sequence[1] == 0xf1: # dial on Q620M, practically 2 buttons
            if sequence[5] == 0x1:
                return 'dial_cw'
            elif sequence[5] == 0xff: 
                return 'dial_ccw'
        else:
            continue

def get_button_release(hidraw):
    while True:
        sequence = hidraw.read(12)
        if sequence[1] == 0xe0 and sequence[4] == 0 and sequence[5] == 0:
            return True


if __name__ == "__main__":
    main()