Polling the keyboard (detect a keypress) in python

You might look at how pygame handles this to steal some ideas.

From the comments:

import msvcrt # built-in module

def kbfunc():
    return ord(msvcrt.getch()) if msvcrt.kbhit() else 0

Thanks for the help. I ended up writing a C DLL called PyKeyboardAccess.dll and accessing the crt conio functions, exporting this routine:

#include <conio.h>

int kb_inkey () {
   int rc;
   int key;

   key = _kbhit();

   if (key == 0) {
      rc = 0;
   } else {
      rc = _getch();
   }

   return rc;
}

And I access it in python using the ctypes module (built into python 2.5):

import ctypes
import time

# first, load the DLL
try:
    kblib = ctypes.CDLL("PyKeyboardAccess.dll")
except:
    raise ("Error Loading PyKeyboardAccess.dll")

# now, find our function
try:
    kbfunc = kblib.kb_inkey
except:
    raise ("Could not find the kb_inkey function in the dll!")

# Ok, now let's demo the capability  
while True:
    x = kbfunc()

    if x != 0:
        print "Got key: %d" % x
    else:
        time.sleep(.01)

Ok, since my attempt to post my solution in a comment failed, here’s what I was trying to say. I could do exactly what I wanted from native Python (on Windows, not anywhere else though) with the following code:

import msvcrt 

def kbfunc(): 
   x = msvcrt.kbhit()
   if x: 
      ret = ord(msvcrt.getch()) 
   else: 
      ret = 0 
   return ret

import sys
import select

def heardEnter():
    i,o,e = select.select([sys.stdin],[],[],0.0001)
    for s in i:
        if s == sys.stdin:
            input = sys.stdin.readline()
            return True
    return False

A solution using the curses module. Printing a numeric value corresponding to each key pressed:

import curses

def main(stdscr):
    # do not wait for input when calling getch
    stdscr.nodelay(1)
    while True:
        # get keyboard input, returns -1 if none available
        c = stdscr.getch()
        if c != -1:
            # print numeric value
            stdscr.addstr(str(c) + ' ')
            stdscr.refresh()
            # return curser to start position
            stdscr.move(0, 0)

if __name__ == '__main__':
    curses.wrapper(main)

If you combine time.sleep, threading.Thread, and sys.stdin.read you can easily wait for a specified amount of time for input and then continue,
also this should be cross-platform compatible.

t = threading.Thread(target=sys.stdin.read(1) args=(1,))
t.start()
time.sleep(5)
t.join()

You could also place this into a function like so

def timed_getch(self, bytes=1, timeout=1):
    t = threading.Thread(target=sys.stdin.read, args=(bytes,))
    t.start()
    time.sleep(timeout)
    t.join()
    del t

Although this will not return anything so instead you should use the multiprocessing pool module you can find that here: how to get the return value from a thread in python?

None of these answers worked well for me. This package, pynput, does exactly what I need.

https://pypi.python.org/pypi/pynput

from pynput.keyboard import Key, Listener

def on_press(key):
    print('{0} pressed'.format(
        key))

def on_release(key):
    print('{0} release'.format(
        key))
    if key == Key.esc:
        # Stop listener
        return False

# Collect events until released
with Listener(
        on_press=on_press,
        on_release=on_release) as listener:
    listener.join()

I am using this for checking for key presses, can’t get much simpler:

#!/usr/bin/python3
# -*- coding: UTF-8 -*-

import curses, time

def main(stdscr):
    """checking for keypress"""
    stdscr.nodelay(True)  # do not wait for input when calling getch
    return stdscr.getch()

while True:
    print("key:", curses.wrapper(main)) # prints: 'key: 97' for 'a' pressed
                                        # '-1' on no presses
    time.sleep(1)

While curses is not working on windows, there is a ‘unicurses’ version, supposedly working on Linux, Windows, Mac but I could not get this to work

I’ve come across a cross-platform implementation of kbhit at http://home.wlu.edu/~levys/software/kbhit.py (made edits to remove irrelevant code):

import os
if os.name == 'nt':
    import msvcrt
else:
    import sys, select

def kbhit():
    ''' Returns True if a keypress is waiting to be read in stdin, False otherwise.
    '''
    if os.name == 'nt':
        return msvcrt.kbhit()
    else:
        dr,dw,de = select.select([sys.stdin], [], [], 0)
        return dr != []

Make sure to read() the waiting character(s) — the function will keep returning True until you do!

This can be done using ‘pynput’ module in python,
You press a key and it gets printed It’s that easy!

1. PIP Install the module in command prompt, write following text and press enter

   pip install pynput

2. Run the following code:

   from pynput.keyboard import Key, Listener
   
   def pressed(key):
       print('Pressed:',key)
   
   def released(key):
       print('Released:',key)
       if key == Key.enter:
           # Stop detecting when enter key is pressed
           return False
   
   # Below loop for Detcting keys runs until enter key is pressed
   with Listener(on_press=pressed, on_release=released) as detector:
       detector.join()
   

3. You can end the loop with any key you want by changing Key.enter to some other key in the 8th line of the code.

One more option would be to use sshkeyboard library to enable reacting to key presses instead of polling them periodically, and potentially missing the key press:

from sshkeyboard import listen_keyboard, stop_listening

def press(key):
    print(f"'{key}' pressed")
    if key == "z":
        stop_listening()

listen_keyboard(on_press=press)

Simply pip install sshkeyboard to use it.