music keys CLI

musicKeys.py

#!/usr/bin/env python
'''
A brittle little program that emits media keys on the :0 X11 display
when it gets certain input characters at the command line.
I use this for transforming my phone into a gestural remote control for my
Google Play Music on my desktop, using Server Auditor as an Android SSH client,
and this extension to listen for media key presses and send them to Google Play Music:
https://chrome.google.com/webstore/detail/key-socket-media-keys/fphfgdknbpakeedbaenojjdcdoajihik
.

I adapt the code from this SO question:
http://stackoverflow.com/questions/22397289/finding-the-values-of-the-arrow-keys-in-python-why-are-they-triples
'''

import sys, tty, termios
from os import system


class _Getch:       
    def __call__(self):
            fd = sys.stdin.fileno()
            old_settings = termios.tcgetattr(fd)
            try:
                tty.setraw(sys.stdin.fileno())
                ch = sys.stdin.read(1)
            finally:
                termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
            return ch


def musNext():
    system('export DISPLAY=:0; xdotool key XF86AudioNext')    
def musPrev():
    system('export DISPLAY=:0; xdotool key XF86AudioPrev')    
def musPlay():
    system('export DISPLAY=:0; xdotool key XF86AudioPlay')    
def volUp():
    system('export DISPLAY=:0; xdotool key XF86AudioRaiseVolume')    
def volDown():
    system('export DISPLAY=:0; xdotool key XF86AudioLowerVolume')    
def volMute():
    system('export DISPLAY=:0; xdotool key XF86AudioMute')    


class Handler(object):
    '''Accumulates a sequence of key ords.
    Starts the sequence from scratch if a control character (ord==27)
    is encountered.
    For a few special keys or sequences, does some actions.'''
    def __init__(self):
        print "press x to exit"
        self.seq = []
    def handle(self, key):
        i = ord(key)
        if i == 32 or i == 9:  # space or tab
            print "toggle play/pause"
            musPlay()
        if i == 109: # m
            print "toggle mute"
            volMute()
        if i == 120: # x
            print "exiting"
            exit()
        if i == 27:  # control character
            self.seq = [] 
        self.seq.append(i)
        if len(self.seq) == 3:
            # first sequence is for desktop; second is for phone
            # (using Server Auditor with the UTF8 charset and xterm "Emulation Type")
            if self.seq[1:] in ([91, 68], [79, 68]):  # left arrow
                print "previous"
                musPrev()
            elif self.seq[1:] in ([91, 67], [79, 67]):  # right arrow
                print "next"
                musNext()
            elif self.seq[1:] in ([91, 65], [79, 65]):  # up arrow
                volUp()
            elif self.seq[1:] in ([91, 66], [79, 66]):  # down arrow
                volDown()

def get(h):
    inkey = _Getch()
    
    while True:
        k=inkey()
        if k!='':
            break
    h.handle(k)

def main():
    h = Handler()
    while True:
        get(h)

if __name__=='__main__':
    main()