Key Listeners in python?
It's unfortunately not so easy to do that. If you're trying to make some sort of text user interface, you may want to look into curses
. If you want to display things like you normally would in a terminal, but want input like that, then you'll have to work with termios
, which unfortunately appears to be poorly documented in Python. Neither of these options are that simple, though, unfortunately. Additionally, they do not work under Windows; if you need them to work under Windows, you'll have to use PDCurses as a replacement for curses
or pywin32 rather than termios
.
I was able to get this working decently. It prints out the hexadecimal representation of keys you type. As I said in the comments of your question, arrows are tricky; I think you'll agree.
#!/usr/bin/env python
import sys
import termios
import contextlib
@contextlib.contextmanager
def raw_mode(file):
old_attrs = termios.tcgetattr(file.fileno())
new_attrs = old_attrs[:]
new_attrs[3] = new_attrs[3] & ~(termios.ECHO | termios.ICANON)
try:
termios.tcsetattr(file.fileno(), termios.TCSADRAIN, new_attrs)
yield
finally:
termios.tcsetattr(file.fileno(), termios.TCSADRAIN, old_attrs)
def main():
print 'exit with ^C or ^D'
with raw_mode(sys.stdin):
try:
while True:
ch = sys.stdin.read(1)
if not ch or ch == chr(4):
break
print '%02x' % ord(ch),
except (KeyboardInterrupt, EOFError):
pass
if __name__ == '__main__':
main()
There is a way to do key listeners in python. This functionality is available through pynput.
Command line:
$ pip install pynput
Python code:
from pynput import keyboard
# your code here
Here's how can do it on Windows:
"""
Display series of numbers in infinite loop
Listen to key "s" to stop
Only works on Windows because listening to keys
is platform dependent
"""
# msvcrt is a windows specific native module
import msvcrt
import time
# asks whether a key has been acquired
def kbfunc():
#this is boolean for whether the keyboard has bene hit
x = msvcrt.kbhit()
if x:
#getch acquires the character encoded in binary ASCII
ret = msvcrt.getch()
else:
ret = False
return ret
#begin the counter
number = 1
#infinite loop
while True:
#acquire the keyboard hit if exists
x = kbfunc()
#if we got a keyboard hit
if x != False and x.decode() == 's':
#we got the key!
#because x is a binary, we need to decode to string
#use the decode() which is part of the binary object
#by default, decodes via utf8
#concatenation auto adds a space in between
print ("STOPPING, KEY:", x.decode())
#break loop
break
else:
#prints the number
print (number)
#increment, there's no ++ in python
number += 1
#wait half a second
time.sleep(0.5)
I was searching for a simple solution without window focus. Jayk's answer, pynput
, works perfect for me. Here is the example how I use it.
from pynput import keyboard
def on_press(key):
if key == keyboard.Key.esc:
return False # stop listener
try:
k = key.char # single-char keys
except:
k = key.name # other keys
if k in ['1', '2', 'left', 'right']: # keys of interest
# self.keys.append(k) # store it in global-like variable
print('Key pressed: ' + k)
return False # stop listener; remove this if want more keys
listener = keyboard.Listener(on_press=on_press)
listener.start() # start to listen on a separate thread
listener.join() # remove if main thread is polling self.keys