Script to pretty-print the codes received for the kitty keyboard protocol

kitty-echo.py

#!/usr/bin/env python3

'''
Program to Show what codes are sent by key presses using the kitty protocol

The flags for progressive-enhancement can be passed as an integer argument (hex is allowed).
Defaults to 1
'''

import sys
import termios
import tty

if len(sys.argv) >= 2:
    # get the mode to use from the first argument
    if sys.argv[1] == 'n':
        flags = None
    else:
        flags = int(sys.argv[1], 0)
else:
    flags = 1

buffer = bytearray(1)

def encoded(b):
    'Encode a byte as printable text'
    if 32 <= b < 127 or b == 0x0A:
        return chr(b)
    elif b == 0x1B:
        return '\\e'
    else:
        return '\\{:02x}'.format(b)


def echo_next():
    'Read the next byte from input, and print a representation of it to stdout'
    if sys.stdin.buffer.readinto(buffer) != 1:
        raise EOFError()
    fwrite(encoded(buffer[0]))
    if buffer == b'Q':
        raise EOFError()

def fwrite(s):
    'Write some output to stdout and flush'
    print(s, end='', flush=True)


old_attrs = tty.setcbreak(sys.stdin)
try:
    # Tell the terminal to use kitty protocol
    # TODO: support using other modes?
    if flags is not None:
        fwrite(f'\x1B[>{flags}u')
    while True:
        # TODO: terminate somehow
        echo_next()
except EOFError:
    pass
finally:
    termios.tcsetattr(sys.stdin, termios.TCSAFLUSH, old_attrs)
    if flags is not None:
        print('\x1B[<u', flush=True)