change_desktop.py

#!/usr/bin/python
 
'''Uses Cocoa classes via PyObjC to set a desktop picture on all screens.
Tested on Mountain Lion and Mavericks. Forked from https://gist.github.com/hunty1/548edaf7e913c8f4e06b,
which was inspired by Greg Neagle's work: https://gist.github.com/gregneagle/6957826
 
See:
https://developer.apple.com/library/mac/documentation/cocoa/reference/applicationkit/classes/NSWorkspace_Class/Reference/Reference.html
 
https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSURL_Class/Reference/Reference.html
 
https://developer.apple.com/library/mac/documentation/cocoa/reference/applicationkit/classes/NSScreen_Class/Reference/Reference.html
'''
 
from AppKit import NSWorkspace, NSScreen
from Foundation import NSURL
import argparse
import sys

parser = argparse.ArgumentParser(description='Sets the desktop picture on all screens.  \
        If more than one image path is provided, will match the file by parameter position \
        to screen index in the NSScreen.screens array.  Otherwise uses first parameter for all screens.')
parser.add_argument('file',
        nargs='+',
        help='The file path to the images.  At least one is required.')
args = vars(parser.parse_args())

if args['file']:
    picture_paths = filter(None, args['file'])
else:
    print >> sys.stderr, 'You must supply a path for the desktop picture'
    exit(-1)
# make image options dictionary
# we just make an empty one because the defaults are fine
options = {}

# get shared workspace
ws = NSWorkspace.sharedWorkspace()
screens = NSScreen.screens()

for index, screen in enumerate(screens):
    try:
        picture_path = picture_paths[index]
    except IndexError:
        picture_path = picture_paths[0]

    file_url = NSURL.fileURLWithPath_(picture_path)

    # tell the workspace to set the desktop picture
    (result, error) = ws.setDesktopImageURL_forScreen_options_error_(
            file_url, screen, options, None)
    if error:
        print error
        exit(-1)