wallpaper.py

# wallpaper.py
# Sets the desktop background to the album art of the current track the user is listening to on lastfm.

import json
import urllib
import urllib2
import subprocess
import re
import time
import cv2

# name of downloaded file
filename = "background.jpg"

# directory where script lives
script_dir = "~/wallpaper/"

# default desktop background
default_background = "/Library/Desktop Pictures/Galaxy.jpg"

# your lastfm username
lastfm_username = "YOUR_USERNAME"

# your lastfm API key
# get one here http://www.last.fm/api/account/create
lastfm_api_key = "YOUR_API_KEY"

# sets background of desktop 2
# see http://stackoverflow.com/questions/431205/how-can-i-programatically-change-the-background-in-mac-os-x
# also http://www.scibuff.com/2009/11/10/applescript-change-the-desktop-picture-wallpaper-of-two-or-more-screens/
SCRIPT = """/usr/bin/osascript<<END
tell application "System Events"
tell desktop 2 to set picture to POSIX file \"%s\"
end tell
END"""

def set_desktop_background(filename):
    subprocess.Popen(SCRIPT%filename, shell=True)

def current_track_img_url():
   params   = {"limit": 1, "user" : lastfm_username}
   response = make_lastfm_request("user.getRecentTracks", params)
   try:
      url = response['recenttracks']['track'][0]['image'][-1]['#text']
   except KeyError, e:
      url = None
   return url

def make_lastfm_request(method, ps):
   lastfm = "http://ws.audioscrobbler.com/2.0/"
   parameters = {"method": method,
                 "api_key": lastfm_api_key,
                 "format": "json"}
   parameters.update(ps)
   data        = urllib.urlencode(parameters)
   req         = urllib2.Request(lastfm, data)
   response    = urllib2.urlopen(req)
   json_object = json.load(response)
   return json_object

currentUrl = ""
x = True
# set to default background initially
set_desktop_background(default_background)
while (1):
   url = current_track_img_url()
   # if the image couldn't be obtained, display the default background
   if url != currentUrl and not url:
      set_desktop_background(default_background)
      currentUrl = url
   # otherwise, show the image for the album cover
   elif url != currentUrl and url:
      urllib.urlretrieve(url, filename)
      # apple only changes the background if the filename has changed
      # so alternate between Truebackground.jpg and Falsebackground.jpg
      # somewhat hacky 
      f = str(x) + filename
      x = not x
      currentUrl = url
      try:
         img = cv2.imread(filename)
         # scale to 800x800 px, chosen arbitrarily
         scaled = cv2.resize(img,(800,800))
         # blur the scaled image
         blurred = cv2.GaussianBlur(scaled,(5,5),0)
         cv2.imwrite(f, blurred)
         set_desktop_background(script_dir + f)
      except cv2.error:
         set_desktop_background(default_background)
   # sleep for 5s between requests
   time.sleep(5)