xsetbg.py

   1 """Set a random background image (XWin)
   2
   3 Select a random image from a (list of) directory(s)
   4 and set it as the desktop wallpaper (display it in the root window)
   5 using xli program.
   6
   7 """
   8
   9 __author__ = "Oleg Broytman <phd@phdru.name>"
  10 __copyright__ = "Copyright (C) 2000-2015 PhiloSoft Design"
  11 __license__ = "GNU GPL"
  12
  13 __all__ = ['change']
  14
  15 from fcntl import flock, LOCK_EX, LOCK_UN, LOCK_NB
  16 from datetime import timedelta
  17 import os
  18 import random
  19 import re
  20 import subprocess
  21 import sys
  22 from time import time
  23
  24 from xsetbg_conf import xsetbg_dir, xsetbg_conf
  25 from xsetbg_db import xsetbg_db
  26
  27
  28 def error(error_str):
  29     sys.exit("%s: Error: %s\n" % (sys.argv[0], error_str))
  30
  31
  32 if not xsetbg_db:
  33     error("No database found. Run rescan_fs.py. Abort.")
  34
  35 if xsetbg_db.select().count() == 0:
  36     error("No images found. Run rescan_fs.py. Abort.")
  37
  38
  39 # minimum time in seconds between background image changes
  40 if xsetbg_conf.has_option("xsetbg", "min_pause"):
  41     min_pause = xsetbg_conf.getint("xsetbg", "min_pause")
  42 else:
  43     min_pause = 60
  44
  45 borders = xsetbg_conf.get("xsetbg", "borders").split(',')
  46 if xsetbg_conf.has_option("xsetbg", "borders"):
  47     borders = [border.strip() for border in
  48                xsetbg_conf.get("xsetbg", "borders").split(',')]
  49 else:
  50     borders = ["darkcyan", "steelblue", "midnightblue"]
  51
  52 # minimum time in seconds between occurences of the same image
  53 if xsetbg_conf.has_option("xsetbg", "min_delay"):
  54     min_delay = xsetbg_conf.get("xsetbg", "min_delay")
  55
  56     # Borrowed from http://stackoverflow.com/a/2765366
  57     td_re = re.compile('(?:(?P<years>\d+)y)?'
  58                        '(?:(?P<months>\d+)m)?'
  59                        '(?:(?P<days>\d+)d)?'
  60                        '(?:T(?:(?P<hours>\d+)h)?'
  61                        '(?:(?P<minutes>\d+)m)?(?:(?P<seconds>\d+)s)?)?')
  62     td_dict = td_re.match(min_delay).groupdict(0)
  63     delta = timedelta(days=int(td_dict['days']) +
  64                       (int(td_dict['months']) * 30) +
  65                       (int(td_dict['years']) * 365),
  66                       hours=int(td_dict['hours']),
  67                       minutes=int(td_dict['minutes']),
  68                       seconds=int(td_dict['seconds']))
  69
  70     if delta:
  71         min_delay = delta.days * 24*3600 + delta.seconds
  72     else:
  73         min_delay = int(min_delay)
  74
  75 else:
  76     min_delay = 3600*24  # 24 hours
  77
  78
  79 if xsetbg_db.select('last_shown IS NULL OR last_shown < %d' %
  80                     (time() - min_delay)).count() == 0:
  81     error("No unshown images found. Run rescan_fs.py "
  82           "or decrease min_delay. Abort.")
  83
  84
  85 def change(force=False):
  86     # Use the program's file as the lock file:
  87     # lock it to prevent two processes run in parallel.
  88     lock_file = open(os.path.join(xsetbg_dir, 'xsetbg.py'), 'r')
  89
  90     try:
  91         flock(lock_file, LOCK_EX | LOCK_NB)
  92     except IOError:  # already locked
  93         lock_file.close()
  94         return
  95
  96     try:
  97         timestamp = xsetbg_db.select('last_shown IS NOT NULL',
  98                                      orderBy='-last_shown')[0].last_shown
  99         current_time = time()
 100
 101         if not force and timestamp is not None and \
 102                 current_time - timestamp < min_pause:
 103             # Too early to change background
 104             return
 105
 106         # Select a random image that has never been shown
 107         not_shown_select = xsetbg_db.select('last_shown IS NULL')
 108         not_shown_count = not_shown_select.count()
 109         if not_shown_count:
 110             row = not_shown_select[random.randint(0, not_shown_count - 1)]
 111         else:
 112             old_shown_select = xsetbg_db.select(
 113                 'last_shown IS NOT NULL AND last_shown < %d' %
 114                 current_time - min_delay)
 115             old_shown_count = old_shown_select.count()
 116             if old_shown_count:
 117                 row = old_shown_select[random.randint(0, old_shown_count - 1)]
 118             else:
 119                 error("No images to show found. Run rescan_fs.py "
 120                       "or decrease min_delay. Abort.")
 121
 122         program_options = ["xli", "-border", random.choice(borders),
 123                            "-center", "-onroot", "-quiet", "-zoom", "auto",
 124                            row.full_name]
 125
 126         rc = subprocess.call(program_options)
 127         if rc:
 128             error("cannot execute xli!")
 129         else:
 130             row.last_shown = current_time
 131
 132     finally:
 133         # Unlock and close the lock file
 134         flock(lock_file, LOCK_UN)
 135         lock_file.close()