Get key presses within a frame on Linux in Python

Question

I'm trying to make a function that, while called, creates a temporary listener (about 0.01s), records keys pressed in that current timeframe, and returns a list of those keys. Something like this would be easy to do with the win32api GetAsyncKeyState , but I'm not quite sure how to do it on Linux.

I found the pynput module to be quite useful, but the way it handles listeners has confused me.

I currently have something like this:

from pynput import keyboard
import time

t0 = time.time()
def on_press_loop(key):
    pressed_keys = []
    if time.time() - t0 < 0.01:
        pressed_keys.append(key.char)
    return pressed_keys

with keyboard.Listener(on_press=on_press_loop) as listener:
    listener.join()

Answer 1

On Posix terminals you have to reconfigure stdin to be non-blocking, and change it back. It can be done in a stand-alone way, but maybe you are better using a 3rdy party library for that.

Terminedia (the development branch) makes the reconfiguration, and hav a getch function that will return the first keypress - it can be easily addaptted for all kepresses on the interval: https://github.com/jsbueno/terminedia/blob/d97976fb11ac54b527db4183497730883ba71515/terminedia/input.py#L116

So, adapting that getch you can use:

from terminedia import keyboard, inkey
import time


def collect_keys(timeout=0.1) -> str:
    """Returns all keys pressed in given time interval
    """
    step = 1 / 30
    ellapsed = step
    with keyboard():
        time.sleep(step)
        key = inkey()
        while True:
            key = inkey()
            time.sleep(step)
            ellapsed += step
            if ellapsed >= timeout:
                break
    return key

You can install the development version with pip install git+https://github.com/jsbueno/terminedia.git - the needed "inkey" and "keyboard" will be available by default when release 0.3 of the project is done.

disclaimer : I am the author of the terminedia package. Although there were hints, sorry for not making it clear from the start.

(Also that code should work on Windows as well)