Set windows wallpaper from python for multiple monitors

This code will allow you to set a different image per monitor for any combination of monitors. Monitors don't have to be the same size, or setup to be square on for it to work. You can have your third monitor straddling the other two, and the wallpaper will be built to accommodate it.

You can now specify per-monitor directory lists if you want.

There are blending and resizing options available too, see the comments.

I've added a setup.py to make a .exe so that the dos window doesn't pop-up.

#!C:/python25/python.exe

# Code to rotate or set wallpaper under windows
# Copyright (C) Andrew K. Milton 2007 - 2010
# Released under a 2-clause BSD License
# See: http://www.opensource.org/licenses/bsd-license.php

# Multi monitor detection based on http://code.activestate.com/recipes/460509/

# This will handle any configuration of an arbitrary number of monitors,
# including offset boundaries.


import os
import sys
import time
import random

from optparse import OptionParser
from ConfigParser import SafeConfigParser
import ctypes

from ctypes import windll

from win32con import *
import win32gui
import win32api
import win32con

from PIL import Image, ImageDraw, ImageChops, ImageOps, ImageFilter


# I recommend you create a pywallpaper.conf file that looks something
# like this to store the directories in rather than specifying -d
# multiple times on the command line.
#
# NB you can specify paths per monitor. Any monitor number without its
# own paths will get the global paths. Monitors start at 0 which is always
# the primary monitor.
#
# Some options don't play nicely together.

"""
[global]
Blending = True
BlendRatio = 0.40
Crop = False
Fill = True
Gradient = False
PreRotate = True

[directories]
paths = C:\Documents and Settings\akm\My Documents\My Pictures\gb
        C:\Documents and Settings\akm\My Documents\My Pictures\Ralph

[monitor_0]
paths = C:\Documents and Settings\akm\My Documents\My Pictures\Wide Screen
[monitor_1]
paths = C:\Documents and Settings\akm\My Documents\My Pictures\Landscapes
"""

# If you don't like the little dos window that pops you can use the
# following as setup.py to create a .exe that won't display the window,
# makes it a little easier to use as a startup item too.

"""
from distutils.core import setup
import py2exe

options = {
    "bundle_files": 2,
    "ascii": 1, # to make a smaller executable, don't include the encodings
    "compressed": 1, # compress the library archive
    "excludes": ['w9xpopen.exe',]
    }

setup( windows = ['pyWallpaper.py'],
       options = {'py2exe': options},
       )
"""


class RECT(ctypes.Structure):
    _fields_ = [
        ('left', ctypes.c_long),
        ('top', ctypes.c_long),
        ('right', ctypes.c_long),
        ('bottom', ctypes.c_long)
        ]
    def dump(self):
        f = (self.left, self.top, self.right, self.bottom)
        return [int(i) for i in f]

class MONITORINFO(ctypes.Structure):
    _fields_ = [
        ('cbSize', ctypes.c_ulong),
        ('rcMonitor', RECT),
        ('rcWork', RECT),
        ('dwFlags', ctypes.c_ulong)
        ]

class Monitor(object):
    def __init__(self, monitor, physical, working, flags):
        self.monitor = monitor
        self.physical = physical
        self.working = working
        self.size = self.getSize(*self.physical)
        self.width, self.height = self.size
        self.left, self.top, self.right, self.bottom = self.physical
        self._left, self._top, self._right, self._bottom = self.physical
        
        self.isPrimary = (flags != 0)

        self.cTop = self.top
        if self.cTop < 0:
            self.cTop = 20000  + self.cTop
        self.cLeft = self.left
        if self.cLeft < 0:
            self.cLeft  = 20000  + self.cLeft

        self.wLeft = int(self.left)
        self.wTop = int(self.top)

        self.needsSplit = ( (self.left < 0 and self.right > 0) or
                            (self.top < 0 and self.bottom > 0) )
        if self.needsSplit:
            self.needVSplit = self.top < 0 and self.bottom > 0
            self.needHSplit = self.left < 0 and self.right > 0

    def addWallpaper(self, bgImage, wallpaper):
        if not self.needsSplit:
            bgImage.paste(wallpaper, (self.wLeft, self.wTop))
            return

        if self.needVSplit:
            height = -self.top
            bottom = wallpaper.crop((0, 0, self.width, height))
            bottom.load()
            top = wallpaper.crop((0, height, self.width, self.height))
            top.load()
            bgImage.paste(top, (self.wLeft, 0))
            bgImage.paste(bottom, (self.wLeft, bgImage.size[1] - height))
        else:
            width = -self.left
            right = wallpaper.crop((0, 0, width, self.height))
            right.load()
            left = wallpaper.crop((width, 0, self.width, self.height))
            left.load()
            bgImage.paste(left, (0, self.wTop))
            bgImage.paste(right, (bgImage.size[0] - width, self.wTop))

            
    def getSize(self, left, top, right, bottom):
        return [abs(right - left), abs(bottom - top)]

    def __repr__(self):
        return 'extent: ' + str(self.physical) + ' :: size: ' + str(self.size) + ' :: primary: ' + str(self.isPrimary) + ' :: needsSplit ' + str(self.needsSplit) + ':: ' + hex(self.monitor)
    def __cmp__(self, other):
        if not cmp(self.cTop, other.cTop):
            return cmp(self.cLeft, other.cLeft)
        return cmp(self.top, other.top)

class Desktop(object):
    def __init__(self):
        self.setMonitorExtents()

        # Merge with the desktop background colour
        # Handy to tint your background to your theme.
        self.Blending = True

        # Amount of picture to bg colour ratio
        # This works well for black...
        self.BlendRatio = 0.40

        # Render a gradient under the image..
        # I'm not overly happy with the results.
        self.Gradient = False

        # Crop black/white borders before zooming
        # This doesn't work well with Fill..
        self.Crop = False

        # Don't just maxpect the image... blow it up so there's no bg colour
        # showing so this will crop parts.
        self.Fill = True

        # If the aspect ratio is "wrong" for the monitor, rotate it for a
        # better fit first. So portraits rotate for landscape monitors.
        # With per-monitor dirs you can sort your pictures based on aspect
        # ratio if you want.
        self.PreRotate = True
        
        self.createEmptyWallpaper()

    def createEmptyWallpaper(self):
        c = (0, 0, 0)

        if self.Blending:
            # Alpha blend the image with the current desktop colour
            # Or black if something goes wrong with getting the desktop colour
            try:
                dc = windll.user32.GetSysColor(1)
                c = ((dc & 0xFF  ),
                     (dc & 0xFF00) >> 8,
                     (dc & 0xFF0000) >> 16)
            except:
                pass

        self.bgColour = c

        bgImage = Image.new('RGB', self.wSize, c)
            
        if self.Gradient:
            r, g, b = c
            width, height = bgImage.size
            fh = float(height)

            if (r + g + b) / 3 < 64:
                r1, g1, b1 = (128, 128, 128)
            else:
                r1, g1, b1 = c
                r, g, b = (64, 64, 64)

            rd = r1 - r
            gd = g1 - g
            bd = b1 - b

            rs = float(rd) / fh
            gs = float(gd) / fh
            bs = float(bd) / fh

            draw = ImageDraw.Draw(bgImage)
            for h in range(0, height):
                draw.line((0, h, width, h),
                          fill = (int(r1), int(g1), int(b1)))
                r1 -= rs
                b1 -= bs
                g1 -= gs
                
        self.bgImage = bgImage

    def findMonitors(self):
        retval = []
        CBFUNC = ctypes.WINFUNCTYPE(ctypes.c_int, ctypes.c_ulong, ctypes.c_ulong, ctypes.POINTER(RECT), ctypes.c_double)
        def cb(hMonitor, hdcMonitor, lprcMonitor, dwData):
            r = lprcMonitor.contents
            data = [hMonitor]
            data.append(r.dump())
            retval.append(data)
            return 1
        cbfunc = CBFUNC(cb)
        temp = windll.user32.EnumDisplayMonitors(0, 0, cbfunc, 0)
        return retval

    def calcWallSize(self):
        # Also sets the relative offsets for building the wallpaper...
        
        ms = self.monitors

        primaryMonitor = [m for m in ms if m.isPrimary][0]

        leftMonitors = [m for m in ms if m.left < 0]
        rightMonitors = [m for m in ms if m.left >= primaryMonitor.right]
        topMonitors = [m for m in ms if m.top < 0]
        bottomMonitors = [m for m in ms if m.top >= primaryMonitor.bottom]

        leftMonitors.sort()
        rightMonitors.sort()
        topMonitors.sort()
        bottomMonitors.sort()

        hMonitors = [primaryMonitor,] + rightMonitors + leftMonitors
        vMonitors = [primaryMonitor,] + bottomMonitors + topMonitors

        width = max([m.right for m in ms])
        height = max([m.bottom for m in ms])

        extraWidth = -min([m.left for m in ms])
        extraHeight = -min([m.top for m in ms])

        width += extraWidth
        height += extraHeight

        hOff = width
        redo = []
        for m in leftMonitors:
            m.wLeft = width + m.left
            if m in bottomMonitors:
                continue
            m.right = width

        for m in topMonitors:
            m.wTop = height + m.top
            if m in rightMonitors:
                continue

            m.bottom = height

        return (width, height)    

    def getMonitors(self):
        retval = []
        for hMonitor, extents in self.findMonitors():
            # data = [hMonitor]
            mi = MONITORINFO()
            mi.cbSize = ctypes.sizeof(MONITORINFO)
            mi.rcMonitor = RECT()
            mi.rcWork = RECT()            
            res = windll.user32.GetMonitorInfoA(hMonitor, ctypes.byref(mi))
            data = Monitor(hMonitor, mi.rcMonitor.dump(), mi.rcWork.dump(), mi.dwFlags)
            retval.append(data)
        return retval
        
    def setMonitorExtents(self):
        self.monitors = self.getMonitors()
        self.wSize = self.calcWallSize()

    def getDefaultDirs(self):
        return [r'C:\Documents and Settings\All Users\Documents\My Pictures\Sample Pictures',]

    def setWallPaperFromBmp(self, pathToBmp):
        """ Given a path to a bmp, set it as the wallpaper """

        # Set it and make sure windows remembers the wallpaper we set.
        result = windll.user32.SystemParametersInfoA(
            SPI_SETDESKWALLPAPER, 0,
            pathToBmp,
            SPIF_UPDATEINIFILE | SPIF_SENDWININICHANGE)
        
        if not result:
            raise Exception("Unable to set wallpaper.")

    def autoCrop(self, im, bgcolor = (0, 0, 0)):
        if im.mode != "RGB":
            im = im.convert("RGB")

        im2 = ImageOps.autocontrast(im, 5)
        bg = Image.new("RGB", im.size, bgcolor)
        diff = ImageChops.difference(im2, bg)
        bbox = diff.getbbox()
        if bbox:
            return im.crop(bbox)
        return im # no contents

    def maxAspectWallPaper_fill(self, image, width, height):
        # Blow up the image making sure that the smallest image aspect
        # fills the monitor.
        
        rsFilter = Image.BICUBIC
        scale = 2.0

        imWidth, imHeight = image.size


        hScale = float(height) / float(imHeight)
        wScale = float(width) / float(imWidth)

        scale = max(hScale, wScale)
            
        if scale < 1:
            rsFilter = Image.ANTIALIAS

        newSize = (int(imWidth * scale), int(imHeight * scale))
        
        newImage = image.resize(newSize, rsFilter)

        if scale > 2:
            newImage = newImage.filter(ImageFilter.BLUR)

        imWidth, imHeight = newSize

        x = int((imWidth - width) / 2.0)
        y = int((imHeight - height) / 2.0)
        bbox = (x, 0, width + x, height + y)
        return newImage.crop(bbox)
    
    def maxAspectWallPaper(self, image, width, height):
        # Blow the image up as much as possible without exceeding the monitor
        # bounds.
        rsFilter = Image.BICUBIC
        scale = 2.0

        imWidth, imHeight = image.size

        hScale = float(height) / float(imHeight)
        wScale = float(width) / float(imWidth)

        if self.Fill:
            scale = max(hScale, wScale)
        else:
            scale = min(hScale, wScale)
            
        if scale < 1:
            rsFilter = Image.ANTIALIAS

        newSize = (int(imWidth * scale), int(imHeight * scale))
        newImage = image.resize(newSize, rsFilter)
        if self.Fill:
            imWidth, imHeight = newSize
            x = int((imWidth - width) / 2.0)
            y = int((imHeight - height) / 2.0)
            bbox = (x, 0, width + x, height + y)
            newImage = newImage.crop(bbox)
        return newImage

    def preRotateImage(self,image):
        # Rotate 90 degrees.
        im = image.rotate(-90, resample = True, expand = True)
        return im

    def createWallPaperFromFile(self, pathToImage, monitor):
        # Given a path to an image, convert it to bmp format and set it as
        # the wallpaper

        bmpImage = Image.open(pathToImage)

        if self.PreRotate:
            if bmpImage.size[0] < bmpImage.size[1]:
                bmpImage = self.preRotateImage(bmpImage)
        
        if self.Crop:
            bmpImage = self.autoCrop(bmpImage, (0,0,0))
            bmpImage = self.autoCrop(bmpImage, (255,255,255))
            
        bmpImage = self.maxAspectWallPaper(bmpImage, *monitor.size)

        bmpSize = bmpImage.size
        xOffset = int((monitor.size[0] - bmpImage.size[0]) / 2)
        yOffset = int((monitor.size[1] - bmpImage.size[1]) / 2)

        if bmpImage.size != monitor.size:
            img1 = Image.new("RGB", monitor.size, (0, 0, 0))
        img1.paste(bmpImage, (xOffset, yOffset))

        if self.Blending:
            img2 = Image.new("RGB", monitor.size, self.bgColour)
            return Image.blend(img2, img1, self.BlendRatio)
        return img1

    def setWallpaperStyleSingle(self):
        # 0x80000001 == HKEY_CURRENT_USER
        k = win32api.RegOpenKeyEx(win32con.HKEY_CURRENT_USER,"Control Panel\\Desktop",0,win32con.KEY_SET_VALUE)
        win32api.RegSetValueEx(k, "WallpaperStyle", 0, win32con.REG_SZ, "0")
        win32api.RegSetValueEx(k, "TileWallpaper", 0, win32con.REG_SZ, "0")

    def setWallpaperStyleMulti(self):
        # To set a multi-monitor wallpaper, we need to tile it...
        # 0x80000001 == HKEY_CURRENT_USER
        k = win32api.RegOpenKeyEx(win32con.HKEY_CURRENT_USER,"Control Panel\\Desktop",0,win32con.KEY_SET_VALUE)
        win32api.RegSetValueEx(k, "WallpaperStyle", 0, win32con.REG_SZ, "0")
        win32api.RegSetValueEx(k, "TileWallpaper", 0, win32con.REG_SZ, "1")

    def setWallpaperStyle(self):
        if len(self.monitors) > 1:
            self.setWallpaperStyleMulti()
        else:
            self.setWallpaperStyleSingle()

    def setWallpaper(self):
        self.setWallpaperStyle()

        # Save the new wallpaper in our current directory.
        newPath = os.getcwd()
        newPath = os.path.join(newPath, 'pywallpaper.bmp')
        self.bgImage.save(newPath, "BMP")
        self.setWallPaperFromBmp(newPath)

    def setWallpaperFromFile(self, pathToImage):
        for monitor in self.monitors:
            img = self.createWallPaperFromFile(filename, monitor)
            monitor.addWallpaper(self.bgImage, img)

        self.setWallpaper()

    def setWallPaperFromFileList(self, pathToDir, monitor):
        """ Given a directory choose an image from it and set it as a wallpaper """
        # Image directories often contain Thumbs.db or other non-image
        # files or directories, try a few times to set a wallpaper, and then just give up.

        tries = 0
        done = False
        filenames = []
        files = os.listdir(pathToDir)

        try:
            # Priorwalls.txt is used so that we don't repeat an image
            # until every other image in that directory has been seen
            # The file is rewritten when necessary.
            prevList = open('priorWalls.txt', 'rb')
            filenames = [l.strip() for l in prevList.readlines()]
            prevList.close()
        except:
            pass

        files = [os.path.join(pathToDir, f) for f in files if not f.endswith('.db')]
        availChoices = [f for f in files if not f in filenames and not f.endswith('.db')]

        if not availChoices:
            # This entire directory has been "done" remove them
            # from the previously seen wallpapers and rewrite
            # the cache file without any of these entries.
            filenames = [f for f in filenames if not f in files]
            availChoices = files
            p = open('priorWalls.txt', 'wb')
            for f in filenames:
                p.write("%s\n"%(f))
            p.close()

        files = availChoices

        while (not done) and tries < 3:
            # Thumbs.db and other stuff can live in the same Folder
            # So try three times to set a wallpaper before giving up.
            try:
                image = random.choice(files)
                filename = image
                img = self.createWallPaperFromFile(filename, monitor)
                monitor.addWallpaper(self.bgImage, img)
                prevList = open('priorWalls.txt', 'ab')
                prevList.write("%s\n"%(filename))
                done = True
            except:
                import traceback; traceback.print_exc()
                print >> sys.stderr, filename, "failed"
                tries += 1
        return done

    def getMonitorDirs(self, monIndex):
        section = 'monitor_%d'%(monIndex)
        # Check for [monitor_0]
        if self.config.has_section(section):
            # check for its own paths section
            if self.config.has_option(section, 'paths'):
                dirs = self.config.get(section, 'paths').split('\n')
        else:
            dirs = self.dirs

        return dirs

    def setWallPaperFromDirList(self):
        """ Given a list of directories choose a directory """
        for monNum, monitor in enumerate(self.monitors):
            imageDir = random.choice(self.getMonitorDirs(monNum))
            status = self.setWallPaperFromFileList(imageDir, monitor)

        self.setWallpaper()

    def getImageDirectories(self):
        # Set global image directories.
        dirs = []
        try:
            dirs = self.config.get('directories', 'paths').split('\n')
        except:
            pass

        if not dirs:
            dirs = self.getDefaultDirs()
        return dirs

    def setWallPaperFromConfigDirs(self):
        self.setWallPaperFromDirList()

    def getConfigFileOptions(self, options):
        configFile = 'pywallpaper.conf'

        if options.configFile:
            configFile = options.configFile

        dirs = options.directories

        self.config = SafeConfigParser()
        self.config.readfp(open(configFile))

        if self.config.has_section('global'):
            self.Blending = self.config.getboolean('global', 'Blending')
            self.BlendRatio = self.config.getfloat('global', 'BlendRatio')
            self.Crop = self.config.getboolean('global', 'Crop')
            self.Fill = self.config.getboolean('global', 'Fill')
            self.Gradient = self.config.getboolean('global', 'Gradient')
            self.PreRotate = self.config.getboolean('global', 'PreRotate')

    def getCommandLineOptions(self):
        parser = OptionParser()
        parser.add_option("-t", "--time", dest="change_time",
                          help = "Change wallpaper time in minutes (0 = change once and exit [default])",
                          default = 0, type = "int")
        parser.add_option("-i", "--image", dest="singleImage", default = None,
                          help = "Set wallpaper to this image and exit (overrides -d)")

        parser.add_option("-d", "--directory", dest="directories", default = [], 
                          action="append", type="string",
                          help = "Add an image directory")

        parser.add_option("-c", "--config", dest="configFile", default = None,
                          help = "path to alternate config file (default <working dir>/pywallpaper.conf)")

        parser.add_option("-w", "--workingdir", dest="cwd", default=".",
                          help = "Working Directory (default .)")

        (options, args) = parser.parse_args()
        return (options, args)

    def go(self):
        options, args = self.getCommandLineOptions()
        self.getConfigFileOptions(options)

        self.dirs = self.getImageDirectories()
        
        if options.cwd and options.cwd != '.':
            os.cwd(cwd)
        if options.singleImage:
            self.setWallPaper(options.singleImage)
            
        elif not options.change_time:
            self.setWallPaperFromConfigDirs()
        else:
            sleepTime = options.change_time * 60.0
            while True:
                self.setWallPaperFromDirList()
                time.sleep(sleepTime)

if __name__ == '__main__':
    d = Desktop()
    d.go()