Scroll with Microsoft Natural® zoom slider

61-microsoft-4000.hwdb

# installed in /etc/udev/hwdb.d/
# after installing run
# $ sudo udevadm hwdb --update
# $ sudo udevadm control --reload

# Microsoft Natural Ergonomic Keyboard 4000
evdev:input:b0003v045Ep00DB*
 KEYBOARD_KEY_c022d=scrollup      # zoomin
 KEYBOARD_KEY_c022e=scrolldown    # zoomout

scroll-mapper.py

#!/usr/bin/env python3
# start as root (I run as systemd service)
# or from group with access to input devices
import sys
import glob

# python-libevdev package on ArchLinux
import libevdev

for f in glob.glob('/dev/input/event*'):
    f = open(f, 'rb')
    d = libevdev.Device(f)
    if 'Microsoft Natural' in d.name and d.has(libevdev.EV_REL.REL_HWHEEL):
        break
    f.close()
else:
    print("Can't find Microsoft Natural device with wheel event")
    sys.exit(1)

fake_mouse = libevdev.Device()
fake_mouse.name = 'fake mouse'
fake_mouse.enable(libevdev.EV_REL.REL_WHEEL)
uinput = fake_mouse.create_uinput_device()
for e in d.events():
    fake_events = []
    if e.matches(libevdev.EV_KEY.KEY_SCROLLUP) and e.value in (1, 2):
        fake_events.append(libevdev.InputEvent(libevdev.EV_REL.REL_WHEEL, value=1))
    if e.matches(libevdev.EV_KEY.KEY_SCROLLDOWN) and e.value in (1, 2):
        fake_events.append(libevdev.InputEvent(libevdev.EV_REL.REL_WHEEL, value=-1))

    if fake_events:
        fake_events.append(libevdev.InputEvent(libevdev.EV_SYN.SYN_REPORT, value=0))
        uinput.send_events(fake_events)