pixel.py

#!/usr/bin/env python2

# Requirements: Python, PyGTK, seems like it wants NumPy as well
# Arch Linux: pygtk, python2-numpy

# Use `xdotool getmouselocation` to find coordinates



coords = (1864, 185)
min_difference = 10 # percent
command = 'mpg123 ping.mp3'
check_interval = 1 # check every second
cooldown = 5*60 # do nothing for 5 minutes after a ping



import subprocess
import time

import gtk.gdk


root_window = gtk.gdk.get_default_root_window()

def pixel_at(x, y):
    pixel_at.pixbuf = pixel_at.pixbuf.get_from_drawable(
        root_window, root_window.get_colormap(), x, y, 0, 0, 1, 1
    )
    return tuple(int(x) for x in pixel_at.pixbuf.pixel_array[0, 0])

pixel_at.pixbuf = gtk.gdk.Pixbuf(gtk.gdk.COLORSPACE_RGB, False, 8, 1, 1)


min_difference *= 256 / 100.0 # convert to 0-255 range

prev_pixel = pixel_at(*coords)
print("Started")
while True:
    time.sleep(check_interval)
    
    pixel = pixel_at(*coords)
    if any(
        abs(a - b) > min_difference # check for difference in every color component individually
        for a, b in zip(prev_pixel, pixel)
    ):
        print("Running {!r}".format(command))
        subprocess.Popen(command, shell=True)
        print("Waiting {} seconds".format(cooldown))
        time.sleep(cooldown)
        print("Resumed")
        pixel = pixel_at(*coords)

    prev_pixel = pixel