xsetbg.py

   1 #! /usr/bin/env python
   2 """Set a random background image (XWin)
   3
   4 Select a random image from a (list of) directory(s)
   5 and set it as the desktop wallpaper (display it in the root window)
   6 using xli program.
   7
   8 """
   9
  10 __author__ = "Oleg Broytman <phd@phdru.name>"
  11 __copyright__ = "Copyright (C) 2000-2014 PhiloSoft Design"
  12 __license__ = "GNU GPL"
  13
  14 __all__ = ['host', 'port', 'change']
  15
  16
  17 import anydbm
  18 from fcntl import flock, LOCK_EX, LOCK_UN, LOCK_NB
  19 from datetime import timedelta
  20 import os
  21 import random
  22 import re
  23 import shelve
  24 import subprocess
  25 import sys
  26 from time import time
  27
  28 from xsetbg_conf import xsetbg_dir, xsetbg_conf
  29 from xsetbg_db import xsetbg_db_path
  30
  31
  32 def error(error_str, error_code=1):
  33    sys.stderr.write("%s: Error: %s\n" % (sys.argv[0], error_str))
  34    sys.exit(error_code)
  35
  36
  37 if xsetbg_conf.has_option("images", "directory") or \
  38    xsetbg_conf.has_option("images", "directory0") or \
  39    xsetbg_conf.has_option("images", "directory1"):
  40    image_dirs = []
  41    if xsetbg_conf.has_option("images", "directory"):
  42       image_dirs.append(xsetbg_conf.get("images", "directory"))
  43    if xsetbg_conf.has_option("images", "directory0"):
  44       image_dirs.append(xsetbg_conf.get("images", "directory0"))
  45    if xsetbg_conf.has_option("images", "directory1"):
  46       image_dirs.append(xsetbg_conf.get("images", "directory1"))
  47    i = 2
  48    while True:
  49       option = "directory%d" % i
  50       if xsetbg_conf.has_option("images", option):
  51          image_dirs.append(xsetbg_conf.get("images", option))
  52          i += 1
  53       else:
  54          break
  55 else:
  56    image_dirs = ["images"]
  57
  58 image_dirs = [os.path.join(xsetbg_dir,
  59    os.path.expandvars(os.path.expanduser(dirname)))
  60       for dirname in image_dirs
  61 ]
  62
  63 # minimum time in seconds between background image changes
  64 if xsetbg_conf.has_option("xsetbg", "min_pause"):
  65    min_pause = xsetbg_conf.getint("xsetbg", "min_pause")
  66 else:
  67    min_pause = 60
  68
  69 borders = xsetbg_conf.get("xsetbg", "borders").split(',')
  70 if xsetbg_conf.has_option("xsetbg", "borders"):
  71    borders = [border.strip() for border in xsetbg_conf.get("xsetbg", "borders").split(',')]
  72 else:
  73    borders = ["darkcyan", "steelblue", "midnightblue"]
  74
  75 # minimum time in seconds between occurences of the same image
  76 if xsetbg_conf.has_option("xsetbg", "min_delay"):
  77    min_delay = xsetbg_conf.get("xsetbg", "min_delay")
  78
  79    # Borrowed from http://stackoverflow.com/a/2765366
  80    td_re  = re.compile('(?:(?P<years>\d+)y)?(?:(?P<months>\d+)m)?(?:(?P<days>\d+)d)?(?:T(?:(?P<hours>\d+)h)?(?:(?P<minutes>\d+)m)?(?:(?P<seconds>\d+)s)?)?')
  81    td_dict = td_re.match(min_delay).groupdict(0)
  82    delta = timedelta(days=int(td_dict['days']) + (int(td_dict['months']) * 30) + (int(td_dict['years']) * 365),
  83                      hours=int(td_dict['hours']),
  84                      minutes=int(td_dict['minutes']),
  85                      seconds=int(td_dict['seconds']))
  86
  87    if delta:
  88       min_delay = delta.days * 24*3600 + delta.seconds
  89    else:
  90       min_delay = int(min_delay)
  91
  92 else:
  93    min_delay = 3600*24 # 24 hours
  94
  95 # httpd settings
  96 if xsetbg_conf.has_option("httpd", "host"):
  97    host = xsetbg_conf.get("httpd", "host")
  98 else:
  99    host = 'localhost'
 100
 101 if xsetbg_conf.has_option("httpd", "port"):
 102    port = xsetbg_conf.getint("httpd", "port")
 103 else:
 104    error("Config must specify a port to listen. Abort.")
 105
 106
 107 # DB keys
 108 timestamp_key = "timestamp"
 109 filename_key = "filename"
 110 old_filename_key = "old_filename"
 111
 112
 113 # Create the database if it is not exists yet.
 114
 115 os.umask(0066) # octal; -rw-------; make the global persistent dictionary
 116                # readable only by the user
 117
 118 try:
 119    xsetbg_db = shelve.open(xsetbg_db_path, flag='c')
 120 except anydbm.error, msg:
 121    if str(msg) == "db type could not be determined":
 122       os.remove(xsetbg_db_path)
 123       xsetbg_db = shelve.open(xsetbg_db_path, flag='c')
 124
 125 # Remove old filenames
 126 old_time = time() - min_delay
 127
 128 to_delete = [timestamp_key]
 129 for key in xsetbg_db.keys():
 130    if key.startswith('/') and xsetbg_db[key] < old_time:
 131       to_delete.append(key)
 132
 133 for key in to_delete:
 134    try:
 135       del xsetbg_db[key]
 136    except KeyError:
 137       pass
 138
 139 xsetbg_db.close() # Close DB in the parent process
 140
 141
 142 images = []
 143
 144 for image_dir in image_dirs:
 145    # List images in all subdirectories
 146    for dirpath, dirs, files in os.walk(image_dir):
 147       images.extend([os.path.join(dirpath, file) for file in files])
 148
 149 if not images:
 150    error("No images found. Abort.")
 151
 152
 153 def change(force=False):
 154    # Use the program's file as the lock file:
 155    # lock it to prevent two processes run in parallel.
 156    lock_file = open(os.path.join(xsetbg_dir, 'xsetbg.py'), 'r')
 157
 158    try:
 159       flock(lock_file, LOCK_EX|LOCK_NB)
 160    except IOError: # already locked
 161       lock_file.close()
 162       return
 163
 164
 165    xsetbg_db = None
 166    try:
 167       # Reopen the global persistent dictionary
 168       xsetbg_db = shelve.open(xsetbg_db_path, 'w')
 169
 170       timestamp = xsetbg_db.get(timestamp_key)
 171       current_time = time()
 172
 173       if not force and timestamp is not None and \
 174          current_time - timestamp < min_pause: # Too early to change background
 175             return
 176
 177       # Save current time
 178       xsetbg_db[timestamp_key] = current_time
 179
 180       # Select a random image and check if we've seen it recently;
 181       # loop until we can find a new image (never seen before) or old enough.
 182       for i in xrange(len(images)): # ensure the loop is not infinite
 183          image_name = random.choice(images)
 184          if xsetbg_db.has_key(image_name):
 185             image_time = xsetbg_db[image_name]
 186             if current_time - image_time > min_delay:
 187                break
 188          else:
 189             break
 190       xsetbg_db[image_name] = current_time
 191
 192       # Save filename
 193       if xsetbg_db.has_key(filename_key):
 194          xsetbg_db[old_filename_key] = xsetbg_db[filename_key]
 195       xsetbg_db[filename_key] = image_name
 196
 197       program_options = ["xli", "-onroot", "-quiet"] + \
 198          ["-center", "-border", random.choice(borders), "-zoom", "auto",
 199             image_name]
 200
 201       rc = subprocess.call(program_options)
 202       if rc:
 203          error("cannot execute xli!")
 204
 205    finally:
 206       # Unlock and close the lock file
 207       flock(lock_file, LOCK_UN)
 208       lock_file.close()
 209       # Flush and close the global persistent dictionary
 210       if xsetbg_db: xsetbg_db.close()