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) 2000-2014 PhiloSoft Design"
  12 __license__ = "GNU GPL"
  13
  14 __all__ = ['change']
  15
  16
  17 import anydbm
  18 from fcntl import flock, LOCK_EX, LOCK_UN, LOCK_NB
  19 from datetime import timedelta
  20 import os
  21 import random
  22 import re
  23 import shelve
  24 import subprocess
  25 import sys
  26 from time import time
  27
  28 from xsetbg_conf import xsetbg_dir, xsetbg_conf
  29 from xsetbg_db import xsetbg_db_path
  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 if xsetbg_conf.has_option("images", "directory") or \
  38    xsetbg_conf.has_option("images", "directory0") or \
  39    xsetbg_conf.has_option("images", "directory1"):
  40    image_dirs = []
  41    if xsetbg_conf.has_option("images", "directory"):
  42       image_dirs.append(xsetbg_conf.get("images", "directory"))
  43    if xsetbg_conf.has_option("images", "directory0"):
  44       image_dirs.append(xsetbg_conf.get("images", "directory0"))
  45    if xsetbg_conf.has_option("images", "directory1"):
  46       image_dirs.append(xsetbg_conf.get("images", "directory1"))
  47    i = 2
  48    while True:
  49       option = "directory%d" % i
  50       if xsetbg_conf.has_option("images", option):
  51          image_dirs.append(xsetbg_conf.get("images", option))
  52          i += 1
  53       else:
  54          break
  55 else:
  56    image_dirs = ["images"]
  57
  58 image_dirs = [os.path.join(xsetbg_dir,
  59    os.path.expandvars(os.path.expanduser(dirname)))
  60       for dirname in image_dirs
  61 ]
  62
  63 # minimum time in seconds between background image changes
  64 if xsetbg_conf.has_option("xsetbg", "min_pause"):
  65    min_pause = xsetbg_conf.getint("xsetbg", "min_pause")
  66 else:
  67    min_pause = 60
  68
  69 borders = xsetbg_conf.get("xsetbg", "borders").split(',')
  70 if xsetbg_conf.has_option("xsetbg", "borders"):
  71    borders = [border.strip() for border in xsetbg_conf.get("xsetbg", "borders").split(',')]
  72 else:
  73    borders = ["darkcyan", "steelblue", "midnightblue"]
  74
  75 # minimum time in seconds between occurences of the same image
  76 if xsetbg_conf.has_option("xsetbg", "min_delay"):
  77    min_delay = xsetbg_conf.get("xsetbg", "min_delay")
  78
  79    # Borrowed from http://stackoverflow.com/a/2765366
  80    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)?)?')
  81    td_dict = td_re.match(min_delay).groupdict(0)
  82    delta = timedelta(days=int(td_dict['days']) + (int(td_dict['months']) * 30) + (int(td_dict['years']) * 365),
  83                      hours=int(td_dict['hours']),
  84                      minutes=int(td_dict['minutes']),
  85                      seconds=int(td_dict['seconds']))
  86
  87    if delta:
  88       min_delay = delta.days * 24*3600 + delta.seconds
  89    else:
  90       min_delay = int(min_delay)
  91
  92 else:
  93    min_delay = 3600*24 # 24 hours
  94
  95
  96 # DB keys
  97 timestamp_key = "timestamp"
  98 filename_key = "filename"
  99 old_filename_key = "old_filename"
 100
 101
 102 # Create the database if it is not exists yet.
 103
 104 os.umask(0066) # octal; -rw-------; make the global persistent dictionary
 105                # readable only by the user
 106
 107 try:
 108    xsetbg_db = shelve.open(xsetbg_db_path, flag='c')
 109 except anydbm.error, msg:
 110    if str(msg) == "db type could not be determined":
 111       os.remove(xsetbg_db_path)
 112       xsetbg_db = shelve.open(xsetbg_db_path, flag='c')
 113
 114 # Remove old filenames
 115 old_time = time() - min_delay
 116
 117 to_delete = [timestamp_key]
 118 for key in xsetbg_db.keys():
 119    if key.startswith('/') and xsetbg_db[key] < old_time:
 120       to_delete.append(key)
 121
 122 for key in to_delete:
 123    try:
 124       del xsetbg_db[key]
 125    except KeyError:
 126       pass
 127
 128 xsetbg_db.close() # Close DB in the parent process
 129
 130
 131 images = []
 132
 133 for image_dir in image_dirs:
 134    # List images in all subdirectories
 135    for dirpath, dirs, files in os.walk(image_dir):
 136       images.extend([os.path.join(dirpath, file) for file in files])
 137
 138 if not images:
 139    error("No images found. Abort.")
 140
 141
 142 def change(force=False):
 143    # Use the program's file as the lock file:
 144    # lock it to prevent two processes run in parallel.
 145    lock_file = open(os.path.join(xsetbg_dir, 'xsetbg.py'), 'r')
 146
 147    try:
 148       flock(lock_file, LOCK_EX|LOCK_NB)
 149    except IOError: # already locked
 150       lock_file.close()
 151       return
 152
 153
 154    xsetbg_db = None
 155    try:
 156       # Reopen the global persistent dictionary
 157       xsetbg_db = shelve.open(xsetbg_db_path, 'w')
 158
 159       timestamp = xsetbg_db.get(timestamp_key)
 160       current_time = time()
 161
 162       if not force and timestamp is not None and \
 163          current_time - timestamp < min_pause: # Too early to change background
 164             return
 165
 166       # Save current time
 167       xsetbg_db[timestamp_key] = current_time
 168
 169       # Select a random image and check if we've seen it recently;
 170       # loop until we can find a new image (never seen before) or old enough.
 171       for i in xrange(len(images)): # ensure the loop is not infinite
 172          image_name = random.choice(images)
 173          if xsetbg_db.has_key(image_name):
 174             image_time = xsetbg_db[image_name]
 175             if current_time - image_time > min_delay:
 176                break
 177          else:
 178             break
 179       xsetbg_db[image_name] = current_time
 180
 181       # Save filename
 182       if xsetbg_db.has_key(filename_key):
 183          xsetbg_db[old_filename_key] = xsetbg_db[filename_key]
 184       xsetbg_db[filename_key] = image_name
 185
 186       program_options = ["xli", "-onroot", "-quiet"] + \
 187          ["-center", "-border", random.choice(borders), "-zoom", "auto",
 188             image_name]
 189
 190       rc = subprocess.call(program_options)
 191       if rc:
 192          error("cannot execute xli!")
 193
 194    finally:
 195       # Unlock and close the lock file
 196       flock(lock_file, LOCK_UN)
 197       lock_file.close()
 198       # Flush and close the global persistent dictionary
 199       if xsetbg_db: xsetbg_db.close()