#!/usr/bin/python

import Xlib
import Xlib.display
import random
import time
import sys
import os


# Quoth http://www.dis.uniroma1.it/~liberato/screensaver/simplesquares.html
#
#    1. Open the display: this is used to connect to the X server, and
#       allows the program to draw.

def run_saver(window=None):

    display = Xlib.display.Display()

#    2. Determine the root window: this is the window that is used by
#       xscreensaver modules as a canvas for drawing.
    rootscreen = display.screen()
    if window:
        window = int(window, 16)
        window = display.create_resource_object('window', window)
    else:
        window = rootscreen.root

#    3. Create a graphic context: a graphic context tells how drawing
#       is made (for example, it contains the foreground color).

    gc = window.create_gc(
        foreground = rootscreen.white_pixel,
        )

#    4. Draw something.

    while True:
        window.rectangle(gc,
                         random.randint(0, 800), # x
                         random.randint(0, 400), # y
                         50, # width
                         40, # height
                         )
        if random.randint(0, 500) < 1:
            window.clear_area(0,0,0,0) # clear_window
#    5. Flush the output (make drawing visible).
        display.flush()
        time.sleep(0.01) # not 10us...


    display.flush()

if __name__ == "__main__":
    run_saver(os.getenv('XSCREENSAVER_WINDOW'))
    # see http://www.dis.uniroma1.it/~liberato/screensaver/install.html
    # for how to configure your .xscreensaver entry