Keyboard LED indicators don't work when grab device

[ellysh]

Hi,

I have a question about your code sample from this issue:
link

This is source code:

dev = InputDevice(...)
dev.grab()

for ev in dev.read_loop():
    if ev.code not in (KEY_LEFTCTRL, KEY_RIGHTCTRL, KEY_Q):
        ui.write_event(ev)
        continue

    # lots of messy checks for when Q is pressed/depressed while a
    # Ctrl key is pressed (ev.value == 1)

The LED indicators don't work when device is grabbed and events are resended by ui.write_event function. Is it possible to fix the LEDs work?

[gvalkov]

Hello,

I must admit I don't know how to fix this at the moment. My initial idea was to add EV_LED and EV_MSC to the UInput constructor (by default, the uinput device can inject only EV_KEY + EV_BTN events).

from evdev import *

cap = {
   ecodes.EV_KEY: list(ecodes.keys.keys()),
   ecodes.EV_LED: list(ecodes.LED.keys())[:-2],
   ecodes.EV_MSC: list(ecodes.MSC.keys())[:-2],
}

dev = InputDevice('/dev/input/event3')
ui = UInput(cap)
dev.grab()

for ev in dev.read_loop():
   ui.write_event(ev)

The events emitted through UInput and those that my keyboard typically emits when NUM_LOCK is pressed apprear to be the same.

I'll look in to it. Thank you for reporting this.

[ellysh]

Thank you very much for your answer!

I will be wait a solution. This is very usefull feature for the keys mapping applications.

[gvalkov]

Hello @ellysh . Pull request #13 introduced a viable workaround to this problem. Leds can now be set through dev.set_led(...).

I'm still not sure why this happens, but I have a feeling it's not entirely related to python-evdev.

[ellysh]

Thank you very much!

Now it works well.