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up vote 3 down vote favorite

I just started python a few days ago, and I haven't programmed much before. I know my code is terrible; however, I would like someone to look it over. What I'm trying to do is create a photo "loop" that changes my Windows 7 login screen. I had a batch file doing it, but even though my code is crappy it does the job way better.

Here is my code, however it limits the number of photos I can have to 9. If I have 10 or more photos, it starts failing and renaming things wrong.

LoginChanger.py

#!/usr/bin/env python
import os

list1 = []
count1 = 0

# Finds jpg files and makes list.
for filename in os.listdir('.'):
    if filename.endswith(('.jpg', '.JPG', 'jpeg', '.JPEG', '.Jpg', '.Jpeg')):
        list1.append(filename)
        list1end = len(list1)

    # Finds background file and sends it to the back of the list.
    if filename.startswith(('BackgroundDefault', 'backgrounddefault')):

        # If name already exists for some reason, makes old file.
        if str(list1end - 1)+'.jpg' in list1:
            os.rename('BackgroundDefault.jpg', 'OldBackground.jpg')
        else:
            os.rename('BackgroundDefault.jpg', str(list1end - 1)+'.jpg')
# Resets The list.
list1 = []

# Creates a list with all jpgs.
for filename in os.listdir('.'):
    if filename.endswith(('.jpg', '.JPG', 'jpeg', '.JPEG', '.Jpg', '.Jpeg')):
        list1.append(filename)
        list1end = len(list1)

# Renames the beginning object of list to background file.
os.rename(list1[0], 'BackgroundDefault.jpg')

# Renames all files incrementally.
while count1 < list1end - 1:
    oldname = list1[count1 + 1]
    os.rename(oldname, str(count1)+'.jpg')
    count1 += 1

print ('Login Background Has Been Changed.')
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2 Answers

up vote 2 down vote accepted

You could avoid continuously renaming all files by overwriting just BackgroundDefault.jpg file instead e.g., change-background.py:

#!/usr/bin/env python
import bisect
import codecs
import os
import shutil

BG_FILE = u'BackgroundDefault.jpg'
db_file = 'change-background.db'
db_encoding = 'utf-8'

# read image filenames; sort to use bisect later
files = sorted(f for f in os.listdir(u'.')
               if f.lower().endswith(('.jpg', '.jpeg')) and os.path.isfile(f)) 
try: files.remove(BG_FILE)
except ValueError: pass # the first run

# read filename to use as a background from db_file
try:
    # support Unicode names, use human-readable format
    with codecs.open(db_file, encoding=db_encoding) as f:
         bg_file = f.read().strip()
except IOError: # the first run
    bg_file = files[0] # at least one image file must be present

# change background image: copy bg_file to BG_FILE
tmp_file = BG_FILE+'.tmp'
shutil.copy2(bg_file, tmp_file)
# make (non-atomic) rename() work even if destination exists on Windows
try: os.remove(BG_FILE)
except OSError: # in use or doesn't exist yet (the first run)
    if os.path.exists(BG_FILE):
       os.remove(tmp_file)
       raise
os.rename(tmp_file, BG_FILE)

# write the next filename to use as a background
next_file = files[bisect.bisect(files, bg_file) % len(files)]
with codecs.open(db_file, 'w', encoding=db_encoding) as f:
     f.write(next_file)
share|improve this answer
I copied this and it worked the first time. Then it said it couldn't change the background image because the file was already there. I had to remove a ")" from "files = sorted(glob.glob(u'*.jpg')))" to get it to work as well. I really appreciate the help though, Thanks. – Jedimaster0 Jan 15 '12 at 3:08
@Jedimaster0: I've fixed the code. I don't use Windows so it is untested. – J.F. Sebastian Jan 15 '12 at 4:18
It works great! thanks. I will try to make my own like this. This gives me a great starting point. – Jedimaster0 Jan 15 '12 at 5:50
up vote 3 down vote
  • Your variable names are pretty bad: filename1, filename2, filename3, ... is bad, use something more meaningful.
  • There is no need to use different loop variables in consecutive loops. Use filename everytime.
  • You need to move the #!/usr/bin/env python shebang line to the first line of the file or it won't work at all.
  • You have unnecessary str() calls in os.rename(str(oldjpg), str(newjpg)) - both variables are already strings.
share|improve this answer
Thanks I will try to apply this. – Jedimaster0 Jan 15 '12 at 3:10

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