# Python program to change the background under windows (tested on windows XP)

from __future__ import division

import sys, os
from PIL import Image

import ctypes
# Kinda like 'from ctypes.windll import user32'
user32 = ctypes.windll.user32

###sys.stdout = file(os.path.join(os.environ['USERPROFILE'], 'Desktop', 'Output.txt'), 'w')
###sys.stderr = sys.stdout

def getUnicodeArgs():
	LocalFree = ctypes.windll.kernel32.LocalFree

	# Defining the GetCommandLineW function
	GetCommandLineW = ctypes.windll.kernel32.GetCommandLineW
	GetCommandLineW.restype = ctypes.c_wchar_p

	# Defining the CommandLineToArgvW function
	CommandLineToArgvW = ctypes.windll.shell32.CommandLineToArgvW
	CommandLineToArgvW.argtypes = (ctypes.c_wchar_p, ctypes.c_void_p)
	CommandLineToArgvW.restype = ctypes.c_void_p

	args = GetCommandLineW()
	# if args != NULL
	if args:
		try:
			numArgs = ctypes.c_int()
			argv_address = CommandLineToArgvW(args, ctypes.byref(numArgs))

			# if argv_address != NULL
			if argv_address:
				try:
					argvArrayType = ctypes.c_wchar_p * numArgs.value
					argvArray = argvArrayType.from_address(argv_address)
					argv = tuple(unicode(arg) for arg in argvArray)
				finally:
					# Free the memory in argv_address
					LocalFree(argv_address)
		finally:
			# Free this memory since it isn't needed
			LocalFree(args)


	# Drop the first argument (since this the call to the python interperator
	return argv[1:]

sys.unicode_argv = getUnicodeArgs()


# Taken from the Platform SDK
SPI_SETDESKWALLPAPER = 20
SPIF_SENDWININICHANGE = 2

# Resize an image (returns a new image)
def resize(image, (outputWidth, outputHeight), 
		fillBoundingBox = False, 
		cropImage = True,
		method = Image.BICUBIC):

	imgWidth, imgHeight = image.size

	if (imgHeight == outputHeight) and (imgWidth == outputWidth):
		return image

	aspectRatio = imgHeight / imgWidth
	outputAspectRatio = outputHeight / outputWidth

	if fillBoundingBox:
		if aspectRatio < outputAspectRatio:
			newHeight = outputHeight
			newWidth = int(outputHeight / aspectRatio)
			# (left, upper, right, lower)
			offset = (newWidth - outputWidth) // 2
			outputBox = (offset, 0, offset + outputWidth, outputHeight)
		else:
			newWidth = outputWidth
			newHeight = int(outputWidth * aspectRatio)
			# (left, upper, right, lower)
			offset = (newHeight - outputHeight) // 2
			outputBox = (0, offset, newWidth, offset + outputHeight)

		print >>sys.stderr, "Aspects: ", aspectRatio, outputAspectRatio
		print >>sys.stderr, "Output: ", outputWidth, outputHeight
		print >>sys.stderr, "Img: ", imgWidth, imgHeight
		print >>sys.stderr, "new:", newWidth, newHeight
		print >>sys.stderr, "CropBox: ", outputBox

		image = image.resize( (newWidth, newHeight), method)
		if cropImage and not\
				((newHeight == outputHeight) and (newWidth == outputWidth)):
			image = image.crop( outputBox )
	else:
		raise NotImplementedError

	return image

# Converts the input image to a bitmap (with optional resizing)
def convertImage(pathToImage, boundingBox = None):
	TEMP_FILE = 'pywallpaper.bmp'
	newPath = os.path.join(os.getcwd(), TEMP_FILE)

	bmpImg = Image.open(pathToImage)

	if boundingBox is not None:
		bmpImg = resize(bmpImg, boundingBox, fillBoundingBox = True)

	# Check the colour space it is in (we only want RGB)
	if bmpImg.mode == 'RGBA':
		bmpImg = bmpImg.convert('RGB')

	# Save it as a bitmap
	bmpImg.save(newPath, "BMP")

	return newPath

# Actually sets the wallpaper
def updateWall(pathToBMP):
	# Parameters for SystemParametersInfoA are:
	# (UINT uiAction, UINT uiParam, PVOID pvParam, UINT fWinIni)
	user32.SystemParametersInfoA(SPI_SETDESKWALLPAPER,
			0,
			pathToBMP,
			SPIF_SENDWININICHANGE)

###
# Code from http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/460509
# Gets the size of all monitors attached to this computer)
###
class RECT(ctypes.Structure):
  _fields_ = [
    ('left', ctypes.c_long),
    ('top', ctypes.c_long),
    ('right', ctypes.c_long),
    ('bottom', ctypes.c_long)
    ]
  def dump(self):
    return map(int, (self.left, self.top, self.right, self.bottom))

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

def get_monitors():
  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
    #print "cb: %s %s %s %s %s %s %s %s" % (hMonitor, type(hMonitor), hdcMonitor, type(hdcMonitor), lprcMonitor, type(lprcMonitor), dwData, type(dwData))
    data = [hMonitor]
    data.append(r.dump())
    retval.append(data)
    return 1
  cbfunc = CBFUNC(cb)
  temp = user32.EnumDisplayMonitors(0, 0, cbfunc, 0)
  #print temp
  return retval

def monitor_areas():
  retval = []
  monitors = get_monitors()
  for hMonitor, extents in monitors:
    data = [hMonitor]
    mi = MONITORINFO()
    mi.cbSize = ctypes.sizeof(MONITORINFO)
    mi.rcMonitor = RECT()
    mi.rcWork = RECT()
    res = user32.GetMonitorInfoA(hMonitor, ctypes.byref(mi))
    data.append(mi.rcMonitor.dump())
    data.append(mi.rcWork.dump())
    retval.append(data)
  return retval

###
# End code from http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/460509
###

def main():
	def getPrimarySize():
		monitors = monitor_areas()
		monitorID, size, workingSize = monitors[0]
		sizeLeft, sizeTop, sizeRight, sizeBottom = size
		return (sizeRight - sizeLeft, sizeBottom - sizeTop)
	
	pathToBMP = convertImage(sys.unicode_argv[1], getPrimarySize())
	updateWall(pathToBMP)

if __name__ == '__main__':
	main()