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) 2000-2012 PhiloSoft Design"
  12 __license__ = "GNU GPL"
  13
  14 __all__ = ['host', 'port', 'change']
  15
  16
  17 import sys, os
  18 from ConfigParser import SafeConfigParser
  19
  20 import anydbm
  21 from datetime import timedelta
  22 import random
  23 import re
  24 import shelve
  25 import subprocess
  26 from time import time
  27 from fcntl import flock, LOCK_EX, LOCK_UN, LOCK_NB
  28
  29 def error(error_str, error_code=1):
  30    sys.stderr.write("%s: Error: %s\n" % (sys.argv[0], error_str))
  31    sys.exit(error_code)
  32
  33
  34 xsetbg_dir = os.path.dirname(os.path.abspath(__file__))
  35 os.chdir(xsetbg_dir)
  36
  37 config = SafeConfigParser()
  38 config.read("xsetbg.conf")
  39
  40 if config.has_option("images", "directory") or \
  41    config.has_option("images", "directory0") or \
  42    config.has_option("images", "directory1"):
  43    image_dirs = []
  44    if config.has_option("images", "directory"):
  45       image_dirs.append(config.get("images", "directory"))
  46    if config.has_option("images", "directory0"):
  47       image_dirs.append(config.get("images", "directory0"))
  48    if config.has_option("images", "directory1"):
  49       image_dirs.append(config.get("images", "directory1"))
  50    i = 2
  51    while True:
  52       option = "directory%d" % i
  53       if config.has_option("images", option):
  54          image_dirs.append(config.get("images", option))
  55          i += 1
  56       else:
  57          break
  58 else:
  59    image_dirs = ["images"]
  60
  61 image_dirs = [os.path.join(xsetbg_dir,
  62    os.path.expandvars(os.path.expanduser(dirname)))
  63       for dirname in image_dirs
  64 ]
  65
  66 # minimum time in seconds between background image changes
  67 if config.has_option("xsetbg", "min_pause"):
  68    min_pause = config.getint("xsetbg", "min_pause")
  69 else:
  70    min_pause = 60
  71
  72 borders = config.get("xsetbg", "borders").split(',')
  73 if config.has_option("xsetbg", "borders"):
  74    borders = [border.strip() for border in config.get("xsetbg", "borders").split(',')]
  75 else:
  76    borders = ["darkcyan", "steelblue", "midnightblue"]
  77
  78 # minimum time in seconds between occurences of the same image
  79 if config.has_option("xsetbg", "min_delay"):
  80    min_delay = config.get("xsetbg", "min_delay")
  81
  82    # Borrowed from http://stackoverflow.com/a/2765366
  83    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)?)?')
  84    td_dict = td_re.match(min_delay).groupdict(0)
  85    delta = timedelta(days=int(td_dict['days']) + (int(td_dict['months']) * 30) + (int(td_dict['years']) * 365),
  86                      hours=int(td_dict['hours']),
  87                      minutes=int(td_dict['minutes']),
  88                      seconds=int(td_dict['seconds']))
  89
  90    if delta:
  91       min_delay = delta.days * 24*3600 + delta.seconds
  92    else:
  93       min_delay = int(min_delay)
  94
  95 else:
  96    min_delay = 3600*24 # 24 hours
  97
  98 # httpd settings
  99 if config.has_option("httpd", "host"):
 100    host = config.get("httpd", "host")
 101 else:
 102    host = 'localhost'
 103
 104 if config.has_option("httpd", "port"):
 105    port = config.getint("httpd", "port")
 106 else:
 107    error("Config must specify a port to listen. Abort.")
 108
 109 del config
 110
 111
 112 os.umask(0066) # octal; -rw-------; make the global persistent dictionary
 113                # readable only by the user
 114 global_db_name = "xsetbg.db"
 115
 116
 117 # DB keys
 118 timestamp_key = "timestamp"
 119 filename_key = "filename"
 120 old_filename_key = "old_filename"
 121
 122
 123 # Create the database if it is not exists yet.
 124
 125 try:
 126    global_db = shelve.open(global_db_name, flag='c')
 127 except anydbm.error, msg:
 128    if str(msg) == "db type could not be determined":
 129       os.remove(global_db_name)
 130       global_db = shelve.open(global_db_name, flag='c')
 131
 132 # Remove old filenames
 133 old_time = time() - min_delay
 134
 135 to_delete = [timestamp_key]
 136 for key in global_db.keys():
 137    if key.startswith('/') and global_db[key] < old_time:
 138       to_delete.append(key)
 139
 140 for key in to_delete:
 141    try:
 142       del global_db[key]
 143    except KeyError:
 144       pass
 145
 146 global_db.close() # Close DB in the parent process
 147
 148
 149 images = []
 150
 151 for image_dir in image_dirs:
 152    # List images in all subdirectories
 153    for dirpath, dirs, files in os.walk(image_dir):
 154       images.extend([os.path.join(dirpath, file) for file in files])
 155
 156 if not images:
 157    error("No images found. Abort.")
 158
 159
 160 def change(force=False):
 161    # Use the program's file as the lock file:
 162    # lock it to prevent two processes run in parallel.
 163    lock_file = open("xsetbg.py", 'r')
 164    try:
 165       flock(lock_file, LOCK_EX|LOCK_NB)
 166    except IOError: # already locked
 167       lock_file.close()
 168       return
 169
 170
 171    global_db = None
 172    try:
 173       # Reopen the global persistent dictionary
 174       global_db = shelve.open(global_db_name, 'w')
 175
 176       timestamp = global_db.get(timestamp_key)
 177       current_time = time()
 178
 179       if not force and timestamp is not None and \
 180          current_time - timestamp < min_pause: # Too early to change background
 181             return
 182
 183       # Save current time
 184       global_db[timestamp_key] = current_time
 185
 186       # Select a random image and check if we've seen it recently;
 187       # loop until we can find a new image (never seen before) or old enough.
 188       for i in xrange(len(images)): # ensure the loop is not infinite
 189          image_name = random.choice(images)
 190          if global_db.has_key(image_name):
 191             image_time = global_db[image_name]
 192             if current_time - image_time > min_delay:
 193                break
 194          else:
 195             break
 196       global_db[image_name] = current_time
 197
 198       # Save filename
 199       if global_db.has_key(filename_key):
 200          global_db[old_filename_key] = global_db[filename_key]
 201       global_db[filename_key] = image_name
 202
 203       program_options = ["xli", "-onroot", "-quiet"] + \
 204          ["-center", "-border", random.choice(borders), "-zoom", "auto",
 205             image_name]
 206
 207       rc = subprocess.call(program_options)
 208       if rc:
 209          error("cannot execute xli!")
 210
 211    finally:
 212       # Unlock and close the lock file
 213       flock(lock_file, LOCK_UN)
 214       lock_file.close()
 215       # Flush and close the global persistent dictionary
 216       if global_db: global_db.close()