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