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
 110 os.umask(0066) # octal; -rw-------; make the global persistent dictionary
 111                # readable only by the user
 112 global_db_name = "xsetbg.db"
 113
 114
 115 # DB keys
 116 timestamp_key = "timestamp"
 117 filename_key = "filename"
 118 old_filename_key = "old_filename"
 119
 120
 121 # Create the database if it is not exists yet.
 122
 123 try:
 124    global_db = shelve.open(global_db_name, flag='c')
 125 except anydbm.error, msg:
 126    if str(msg) == "db type could not be determined":
 127       os.remove(global_db_name)
 128       global_db = shelve.open(global_db_name, flag='c')
 129
 130 # Remove old filenames
 131 old_time = time() - min_delay
 132
 133 to_delete = [timestamp_key]
 134 for key in global_db.keys():
 135    if key.startswith('/') and global_db[key] < old_time:
 136       to_delete.append(key)
 137
 138 for key in to_delete:
 139    try:
 140       del global_db[key]
 141    except KeyError:
 142       pass
 143
 144 global_db.close() # Close DB in the parent process
 145
 146
 147 images = []
 148
 149 for image_dir in image_dirs:
 150    # List images in all subdirectories
 151    for dirpath, dirs, files in os.walk(image_dir):
 152       images.extend([os.path.join(dirpath, file) for file in files])
 153
 154 if not images:
 155    error("No images found. Abort.")
 156
 157
 158 def change(force=False):
 159    # Use the program's file as the lock file:
 160    # lock it to prevent two processes run in parallel.
 161    lock_file = open("xsetbg.py", 'r')
 162    try:
 163       flock(lock_file, LOCK_EX|LOCK_NB)
 164    except IOError: # already locked
 165       lock_file.close()
 166       return
 167
 168
 169    global_db = None
 170    try:
 171       # Reopen the global persistent dictionary
 172       global_db = shelve.open(global_db_name, 'w')
 173
 174       timestamp = global_db.get(timestamp_key)
 175       current_time = time()
 176
 177       if not force and timestamp is not None and \
 178          current_time - timestamp < min_pause: # Too early to change background
 179             return
 180
 181       # Save current time
 182       global_db[timestamp_key] = current_time
 183
 184       # Select a random image and check if we've seen it recently;
 185       # loop until we can find a new image (never seen before) or old enough.
 186       for i in xrange(len(images)): # ensure the loop is not infinite
 187          image_name = random.choice(images)
 188          if global_db.has_key(image_name):
 189             image_time = global_db[image_name]
 190             if current_time - image_time > min_delay:
 191                break
 192          else:
 193             break
 194       global_db[image_name] = current_time
 195
 196       # Save filename
 197       if global_db.has_key(filename_key):
 198          global_db[old_filename_key] = global_db[filename_key]
 199       global_db[filename_key] = image_name
 200
 201       program_options = ["xli", "-onroot", "-quiet"] + \
 202          ["-center", "-border", random.choice(borders), "-zoom", "auto",
 203             image_name]
 204
 205       rc = subprocess.call(program_options)
 206       if rc:
 207          error("cannot execute xli!")
 208
 209    finally:
 210       # Unlock and close the lock file
 211       flock(lock_file, LOCK_UN)
 212       lock_file.close()
 213       # Flush and close the global persistent dictionary
 214       if global_db: global_db.close()