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