I would like to simulate a graphics tablet (like wacom's ones) from a script. The "good" way to proceed seems to use libevent that is an abstract layer above uinput. So I tried to write a script that sends some event like EV_ABS.ABS_X or EV_ABS.ABS_PRESSURE, using the python library of libevent. Unfortunately, when I use Krita/Gimp/... to test it, the line that it draws does not change it's shape depending on the pressure, and xinput test-xi2 does not display any pressure event. Any idea why?
Thanks!
Steps to reproduce
Execute the code below:
sudo pip3 install libevdev
chmod +x ./simulate_graphics_tablet.py
sudo ./simulate_graphics_tablet.py
Then you have 30 seconds to:
- either run
xinput listand thenxinput test-xi2 <number of Tablet alone> - or open Gimp, go to 'Edit/Input device' and configure the device 'Tablet alone' to 'Screen', save and close the pop up,create a new file (Ctrl-N), Zoom and press 'tab' to have a drawing surface covering most of the screen. Switch to brush using 'p' key, by making sure the brush is set to
Pressure size.
What I get: a uniform line, and on xinput I don't have any reference to pressure and I just have things like:
EVENT type 17 (RawMotion)
device: 11 (11)
detail: 0
flags:
valuators:
0: 29897.54 (29897.54)
1: 29897.54 (29897.54)
What I expect: a line whose size is not constatn (the script increase the pressure linearly), or to see some pressure-related events on xinput.
#!/usr/bin/env python3
import sys
import libevdev
import time
def main(args):
dev = libevdev.Device()
dev.name = "Tablet alone"
dev.enable(libevdev.EV_ABS.ABS_X,
libevdev.InputAbsInfo(minimum=0, maximum=32767))
dev.enable(libevdev.EV_ABS.ABS_Y,
libevdev.InputAbsInfo(minimum=0, maximum=32767))
dev.enable(libevdev.EV_ABS.ABS_Z,
libevdev.InputAbsInfo(minimum=0, maximum=8191))
# dev.enable(libevdev.EV_ABS.ABS_0B,
# libevdev.InputAbsInfo(minimum=0, maximum=8191))
# dev.enable(libevdev.EV_ABS.ABS_DISTANCE,
# libevdev.InputAbsInfo(minimum=0, maximum=8191))
dev.enable(libevdev.EV_ABS.ABS_PRESSURE,
libevdev.InputAbsInfo(minimum=0, maximum=8191))
dev.enable(libevdev.EV_MSC.MSC_SCAN)
dev.enable(libevdev.EV_KEY.KEY_P)
dev.enable(libevdev.EV_KEY.BTN_LEFT)
dev.enable(libevdev.EV_KEY.BTN_RIGHT)
dev.enable(libevdev.EV_KEY.BTN_MIDDLE)
dev.enable(libevdev.EV_KEY.BTN_TOUCH)
dev.enable(libevdev.EV_SYN.SYN_REPORT)
dev.enable(libevdev.EV_SYN.SYN_CONFIG)
dev.enable(libevdev.EV_SYN.SYN_MT_REPORT)
dev.enable(libevdev.EV_SYN.SYN_DROPPED)
dev.enable(libevdev.EV_SYN.SYN_04)
dev.enable(libevdev.EV_SYN.SYN_05)
dev.enable(libevdev.EV_SYN.SYN_06)
dev.enable(libevdev.EV_SYN.SYN_07)
dev.enable(libevdev.EV_SYN.SYN_08)
dev.enable(libevdev.EV_SYN.SYN_09)
dev.enable(libevdev.EV_SYN.SYN_0A)
dev.enable(libevdev.EV_SYN.SYN_0B)
dev.enable(libevdev.EV_SYN.SYN_0C)
dev.enable(libevdev.EV_SYN.SYN_0D)
dev.enable(libevdev.EV_SYN.SYN_0E)
dev.enable(libevdev.EV_SYN.SYN_MAX)
try:
uinput = dev.create_uinput_device()
print("New device at {} ({})".format(uinput.devnode, uinput.syspath))
# Sleep for a bit so udev, libinput, Xorg, Wayland, ...
# all have had a chance to see the device and initialize
# it. Otherwise the event will be sent by the kernel but
# nothing is ready to listen to the device yet.
print("Waiting 30s to let you:")
print("1) open Gimp")
print("2) Go to 'Edit/Input device' and configure the device 'Tablet alone' to 'Screen'.")
print("3) Save and close the pop up")
print("4) Create a new file (Ctrl-N)")
print("5) Zoom and press 'tab' to have a drawing surface coverint most of the screen.")
print("6) Switch to brush using 'p' key.")
time.sleep(30)
pc = 0
direc = +1
already_pressed_one = False
# uinput.send_events([
# libevdev.InputEvent(libevdev.EV_KEY.KEY_P, 1),
# libevdev.InputEvent(libevdev.EV_SYN.SYN_REPORT, 0),
# ])
# time.sleep(0.1)
# uinput.send_events([
# libevdev.InputEvent(libevdev.EV_KEY.KEY_P, 0),
# libevdev.InputEvent(libevdev.EV_SYN.SYN_REPORT, 0),
# ])
for i in range(250):
pc_ = pc/100
val_x = int(pc_*10000 + (1-pc_)*17767)
val_y = int(pc_*5000 + (1-pc_)*22767)
val_pres = int(pc_*10 + (1-pc_)*6000)
print("Will send: x={}, y={}, press={} (pc={})".format(
val_x,
val_y,
val_pres,
pc))
uinput.send_events([
libevdev.InputEvent(libevdev.EV_ABS.ABS_PRESSURE, val_pres),
libevdev.InputEvent(libevdev.EV_ABS.ABS_X, val_y),
libevdev.InputEvent(libevdev.EV_ABS.ABS_Y, val_y),
libevdev.InputEvent(libevdev.EV_SYN.SYN_REPORT, 0),
])
pc += direc
if not already_pressed_one:
print("Press!")
uinput.send_events([
libevdev.InputEvent(libevdev.EV_KEY.BTN_LEFT, 1),
libevdev.InputEvent(libevdev.EV_SYN.SYN_REPORT, 0),
])
already_pressed_one = True
if pc >= 100 or pc <=0 :
print("Release click.")
uinput.send_events([
libevdev.InputEvent(libevdev.EV_KEY.BTN_LEFT, 0),
libevdev.InputEvent(libevdev.EV_SYN.SYN_REPORT, 0),
])
if pc >= 100:
pc = 100
direc = -1
if pc <= 0:
pc = 0
direc = +1
time.sleep(10)
print("Press!")
uinput.send_events([
libevdev.InputEvent(libevdev.EV_KEY.BTN_LEFT, 1),
libevdev.InputEvent(libevdev.EV_SYN.SYN_REPORT, 0),
])
already_pressed_one = True
time.sleep(0.1)
except KeyboardInterrupt:
pass
except OSError as e:
print(e)
if __name__ == "__main__":
if len(sys.argv) > 2:
print("Usage: {}")
sys.exit(1)
main(sys.argv)
EDIT:
I tried to play with ABS_KEY.BTN_TOOL_PEN as explained here, but I don't know why the second I enable it it stops being detected by xinput list:
dev.enable(libevdev.EV_KEY.BTN_TOOL_PEN)
