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