chmod a+x ~/Pictures/DeskFeed/deskfeed.py
~/Pictures/DeskFeed/deskfeed.py

This will automatically download the latest photos from the Chromasia and daily dose of imagery blogs, and save them in the DeskFeed folder. To modify which feeds are downloaded (or not), open the deskfeed.py file you just downloaded and comment out / uncomment the photo feeds you want on the first few lines that are clearly marked. You can have as many feeds as you want in the script, but they have to be generated from the App Engine script which I wrote.

To set this up as a periodic task using cron, create a text file on your desktop called dfcron, and in it place this single line:

5      1       *       *       *       /Users/username/Pictures/DeskFeed/deskfeed.py

Make sure you replace username with your own short username. What this file contains is a command that will tell cron to run the deskfeed.py file every day at 5 minutes past 1am. Then, run this command in the terminal once:

crontab ~/Desktop/dfcron

You can now safely delete dfcron. To set this folder as your desktop background, go to System Preferences / Desktop & Screen Saver, press the little '+' button under the list of folders, navigate to the DeskFeed folder, and select Choose. I found that "Fit to Screen" with a black background works best.

I am open to suggestions about what other photo feeds to include in this application, it only takes about 10 minutes to add a new feed. Furthermore, I will be creating a more solid application that will be customisable through preferences rather than relying on a Python script. But as this is a first attempt, I'm publishing the code to the script to see if anyone else has any suggestions for improvement. If you just want to look at the code used instead of downloading the above file, here it is:

#!/usr/bin/env python
import os
import md5
from urllib import URLopener
from urllib2 import urlopen
from xml.dom.minidom import parseString
 
rss_feeds = {}
 
#
# Comment / Uncomment the following lines to use the required feeds
#
rss_feeds['chromasia'] = 'http://deskfeed.neophytou.net/rss/chromasia'
rss_feeds['ddoi'] = 'http://deskfeed.neophytou.net/rss/ddoi'
 
dst_dir = os.path.expanduser('~/Pictures/DeskFeed/')
 
# Based on script found at HackerMoJo.com
# http://hackermojo.com/mt-static/archives/2008/04/metropulse-launched.html
def parseFeed(rss):
  try:
    rss_contents = urlopen( rss )
  except:
    print "Failed to read rss feed %s" % rss
    return
  rss_src = rss_contents.read()
  rss_contents.close()
  dom = parseString( rss_src )
  node_lst = dom.getElementsByTagName('item')
  items = range(node_lst.length)
  hashes = {}
  group = node_lst.item(0).getElementsByTagName('title')[0].getAttribute('group')
  # Store the md5 hashes of all the saved photos
  for i in items:
    img_filename = "%s%s_%s.jpg" % (dst_dir,group,i)
    try:
      image_file = open(img_filename, "r")
      hashes[img_filename] = md5.md5(image_file.read()).hexdigest()
      image_file.close()
    except IOError:
      hashes[img_filename] = ""
      pass
  # Go through all the photos in the rss feed, in reverse order
  items.reverse()
  for i in items:
    element = node_lst.item(i)
    group = element.getElementsByTagName( 'title' )[0].getAttribute('group')
    link = element.getElementsByTagName( 'link' )[0].getAttribute('source')
    photo_hash = element.getElementsByTagName('hash')[0].firstChild.data
    img_filename = "%s%s_%s.jpg" % (dst_dir, group, i)
    # Check all the saved photos and see if any of them have the same hash
    for j in range(i):
      old_img_filename = "%s%s_%s.jpg" % (dst_dir, group, j)
      if (hashes[old_img_filename] == photo_hash):
        # If one does, give it the current photo filename
        os.system("mv %s %s" % (old_img_filename, img_filename))
        hashes[old_img_filename] = ""
        hashes[img_filename] = photo_hash
        break
    try:
      image_file = open(img_filename, "r")
      old_hash = md5.md5(image_file.read()).hexdigest()
      image_file.close()
      if (old_hash == photo_hash):
        continue
    except IOError:
      pass
    try:
      URLopener().retrieve(link, img_filename)
    except IOError:
      continue
 
def main():
  for key in rss_feeds:
    parseFeed(rss_feeds[key])
 
if __name__ == "__main__":
  main()

Download this script

That's pretty much it. As you can see, the script is not that complicated, and I can very easily modify the way the photos are served to the clients. This code has been tested under Leopard using Python 2.5, but also under Ubuntu using Python 2.4.3, and I believe it should also work under Tiger using Python 2.3, but I could very well be wrong. So as always, I'm open to feedback and suggestions. If anyone knows how to create a Preference pane, please contact me. I know exactly what needs to be done in the Preference pane, but I have no idea how to use Xcode.]]> http://www.cneophytou.com/2008/04/17/photo-feed-as-desktop-background/feed/ 10 http://www.cneophytou.com/2008/04/17/downloading-your-code-from-google-app-engine/ http://www.cneophytou.com/2008/04/17/downloading-your-code-from-google-app-engine/#comments Thu, 17 Apr 2008 14:42:23 +0000 Constantinos http://www.cneophytou.com/?p=112 App Engine since it launched, mostly playing around with Python (always wanted to learn), and setting up a small app to deal with my Desktop Photo Feed script. One irritation I had was that I wanted to share my code with a friend, but the app engine doesn't provide any way of downloading the source code.

One way around this that I found, was a blog post by David Burger on Download Your Code from Google App Engine, where he created a Makefile to do the dirtywork. Because I don't like Makefiles (and have it from good authority that Googlers hate Makefiles too, but that's besides the point - just to reinforce my position), I modified his method to make it slightly more versatile so that it can work well with OS X (tar includes ._* resource fork files which are annoying), and also turn it into a shell script.

There are two steps to the process. First, save this code as a file called something like update.sh in the base folder where your app code is located, and make it executable:

ARCHIVE_DIR=archive
ARCHIVE_NAME=`basename $PWD`.tgz
 
rm -rf ${ARCHIVE_DIR}
find . -name "*~" -delete
find . -name "*pyc" -delete
export COPY_EXTENDED_ATTRIBUTES_DISABLE=true
export COPYFILE_DISABLE=true
tar -czf ${ARCHIVE_NAME} --exclude .DS_Store --exclude ${ARCHIVE_NAME} -C ../ `basename $PWD`
mkdir -p ${ARCHIVE_DIR}
mv ${ARCHIVE_NAME} ${ARCHIVE_DIR}
appcfg.py update ./

Download this script

Then, you would probably want to password protect the resource that points to this archive file, so add this to your app.yaml file:

- url: /archive
  static_dir: archive
  login: admin

Now, whenever you wish to update your app, just execute ./update.sh instead of ./appcfg.py update ./, and the archive of your source will be created and uploaded with your changes. To download, assuming the folder your application is in has the same name as your application, just visit http://yourapp.appspot.com/archive/yourapp.tgz where yourapp is your app's name, and yourapp.tgz is your app folder's name if it's different from your app's name, and you will be prompted to download the archive assuming you're logged in as administrator. That's it!]]> http://www.cneophytou.com/2008/04/17/downloading-your-code-from-google-app-engine/feed/ 1