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 or xsetbg programs.
   7
   8 """
   9
  10 __version__ = "$Revision$"[11:-2]
  11 __revision__ = "$Id$"[5:-2]
  12 __date__ = "$Date$"[7:-2]
  13
  14 __author__ = "Oleg Broytman <phd@phd.pp.ru>"
  15 __copyright__ = "Copyright (C) 2000-2010 PhiloSoft Design"
  16 __license__ = "GNU GPL"
  17
  18
  19 import sys, os
  20 import subprocess
  21
  22
  23 def error(error_str, error_code=1):
  24    sys.stderr.write("%s: Error: %s\n" % (sys.argv[0], error_str))
  25    sys.exit(error_code)
  26
  27
  28 from ConfigParser import SafeConfigParser
  29
  30 xsetbg_dir = os.path.dirname(os.path.abspath(__file__))
  31 os.chdir(xsetbg_dir)
  32
  33 config = SafeConfigParser()
  34 config.read("xsetbg.conf")
  35
  36 if config.has_option("images", "directory") or \
  37    config.has_option("images", "directory0") or \
  38    config.has_option("images", "directory1"):
  39    image_dirs = []
  40    if config.has_option("images", "directory"):
  41       image_dirs.append(config.get("images", "directory"))
  42    if config.has_option("images", "directory0"):
  43       image_dirs.append(config.get("images", "directory0"))
  44    if config.has_option("images", "directory1"):
  45       image_dirs.append(config.get("images", "directory1"))
  46    i = 2
  47    while True:
  48       option = "directory%d" % i
  49       if config.has_option("images", option):
  50          image_dirs.append(config.get("images", option))
  51          i += 1
  52       else:
  53          break
  54 else:
  55    image_dirs = ["images"]
  56
  57 image_dirs = [os.path.join(xsetbg_dir,
  58    os.path.expandvars(os.path.expanduser(dirname)))
  59       for dirname in image_dirs
  60 ]
  61
  62 # minimum time in seconds between background image changes
  63 if config.has_option("xsetbg", "min_pause"):
  64    min_pause = config.getint("xsetbg", "min_pause")
  65 else:
  66    min_pause = 60
  67
  68 borders = config.get("xsetbg", "borders").split(',')
  69 if config.has_option("xsetbg", "borders"):
  70    borders = [border.strip() for border in config.get("xsetbg", "borders").split(',')]
  71 else:
  72    borders = ["darkcyan", "steelblue", "midnightblue"]
  73
  74 # minimum time in seconds between occurences of the same image
  75 if config.has_option("xsetbg", "min_delay"):
  76    min_delay = config.getint("xsetbg", "min_delay")
  77 else:
  78    min_delay = 3600*24 # 24 hours
  79
  80 # httpd settings
  81 if config.has_option("httpd", "host"):
  82    host = config.get("httpd", "host")
  83 else:
  84    host = 'localhost'
  85
  86 if config.has_option("httpd", "port"):
  87    port = config.getint("httpd", "port")
  88 else:
  89    error("Config must specify a port to listen. Abort.")
  90
  91 del config
  92
  93
  94 os.umask(0066) # octal; -rw-------; make the global persistent dictionary
  95                # readable only by the user
  96 global_db_name = "xsetbg.db"
  97
  98
  99 # DB keys
 100 timestamp_key = "timestamp"
 101 filename_key = "filename"
 102 old_filename_key = "old_filename"
 103
 104
 105 import random
 106 import anydbm, shelve
 107 from time import time
 108 from fcntl import flock, LOCK_EX, LOCK_UN, LOCK_NB
 109
 110 # Create the database if it is not exists yet.
 111
 112 try:
 113    global_db = shelve.open(global_db_name, flag='c')
 114 except anydbm.error, msg:
 115    if str(msg) == "db type could not be determined":
 116       os.remove(global_db_name)
 117       global_db = shelve.open(global_db_name, flag='c')
 118
 119 # Remove old filenames
 120 old_time = time() - min_delay
 121
 122 to_delete = [timestamp_key]
 123 for key in global_db.keys():
 124    if key.startswith('/') and global_db[key] < old_time:
 125       to_delete.append(key)
 126
 127 for key in to_delete:
 128    try:
 129       del global_db[key]
 130    except KeyError:
 131       pass
 132
 133 global_db.close() # Close DB in the parent process
 134
 135
 136 images = []
 137
 138 for image_dir in image_dirs:
 139    # List images in all subdirectories
 140    for dirpath, dirs, files in os.walk(image_dir):
 141       images.extend([os.path.join(dirpath, file) for file in files])
 142
 143 if not images:
 144    error("No images found. Abort.")
 145
 146
 147 def published(func):
 148     func._wsgi_published = True
 149     return func
 150
 151 @published
 152 def ping(force=False):
 153    # Use the program's file as the lock file:
 154    # lock it to prevent two processes run in parallel.
 155    lock_file = open("xsetbg.py", 'r')
 156    try:
 157       flock(lock_file, LOCK_EX|LOCK_NB)
 158    except IOError: # already locked
 159       lock_file.close()
 160       return
 161
 162
 163    global_db = None
 164    try:
 165       # Reopen the global persistent dictionary
 166       global_db = shelve.open(global_db_name, 'w')
 167
 168       timestamp = global_db.get(timestamp_key)
 169       current_time = time()
 170
 171       if not force and timestamp is not None and \
 172          current_time - timestamp < min_pause: # Too early to change background
 173             return
 174
 175       # Save current time
 176       global_db[timestamp_key] = current_time
 177
 178       # Select a random image and check if we've seen it recently;
 179       # loop until we can find a new image (never seen before) or old enough.
 180       for i in xrange(len(images)): # ensure the loop is not infinite
 181          image_name = random.choice(images)
 182          if global_db.has_key(image_name):
 183             image_time = global_db[image_name]
 184             if current_time - image_time > min_delay:
 185                break
 186          else:
 187             break
 188       global_db[image_name] = current_time
 189
 190       # Save filename
 191       if global_db.has_key(filename_key):
 192          global_db[old_filename_key] = global_db[filename_key]
 193       global_db[filename_key] = image_name
 194
 195       program_options = ["xli", "-onroot", "-quiet"] + \
 196          ["-center", "-border", random.choice(borders), "-zoom", "auto",
 197             image_name]
 198
 199       rc = subprocess.call(program_options)
 200       if rc:
 201          error("cannot execute xli!")
 202
 203    finally:
 204       # Unlock and close the lock file
 205       flock(lock_file, LOCK_UN)
 206       lock_file.close()
 207       # Flush and close the global persistent dictionary
 208       if global_db: global_db.close()
 209
 210 @published
 211 def force():
 212     ping(force=True)
 213
 214 @published
 215 def stop():
 216     QuitWSGIServer._quit_flag = True
 217
 218
 219 from wsgiref.handlers import SimpleHandler
 220 from wsgiref import simple_server
 221 simple_server.ServerHandler = SimpleHandler # Stop logging to stdout
 222 from wsgiref.simple_server import WSGIServer, make_server
 223
 224 g = globals().copy()
 225 commands = dict([(name, g[name]) for name in g
 226     if getattr(g[name], '_wsgi_published', False)])
 227 del g
 228
 229 class QuitWSGIServer(WSGIServer):
 230     _quit_flag = False
 231
 232     def serve_forever(self):
 233         while not self._quit_flag:
 234             self.handle_request()
 235
 236 def app(env, start_response):
 237     command = env['PATH_INFO'][1:] # Remove the leading slash
 238     if command not in commands:
 239         status = '404 Not found'
 240         response_headers = [('Content-type', 'text/plain')]
 241         start_response(status, response_headers)
 242         return ['The command was not found.\n']
 243
 244     try:
 245         commands[command]()
 246     except:
 247         status = '500 Error'
 248         response_headers = [('Content-type', 'text/plain')]
 249         start_response(status, response_headers)
 250         return ['Error occured!\n']
 251
 252     status = '200 OK'
 253     response_headers = [('Content-type', 'text/plain')]
 254     start_response(status, response_headers)
 255     return ['Ok\n']
 256
 257 force()
 258 httpd = make_server(host, port, app, server_class=QuitWSGIServer)
 259 httpd.serve_forever()