Change Windows 10 background in Python 3

Question

I've been trying to find the best way to change the Windows 10 Desktop wallpaper through a python script. When I try to run this script, the desktop background turns to a solid black color.

import ctypes

path = 'C:\\Users\\Patrick\\Desktop\\0200200220.jpg'

def changeBG(path):
    SPI_SETDESKWALLPAPER = 20
    ctypes.windll.user32.SystemParametersInfoA(20, 0, path, 3)
    return;

changeBG(path)

What can I do to fix this? I'm using python3

I'm running macOS but check if you can use this as reference. https://www.techwalla.com/articles/script-to-change-desktop-background. It involves 2 steps. Changing the path to the desktop wallpaper you want and sending a system update command using user32.dll,UpdatePerUserSystemParameters", 1, True. This update command is included in most guides I've read. — fcsr, Dec 21 '18 at 02:42

RoadRunner · Accepted Answer · 2018-12-21T18:34:16.547

For 64 bit windows, use:

ctypes.windll.user32.SystemParametersInfoW

for 32 bit windows, use:

ctypes.windll.user32.SystemParametersInfoA

If you use the wrong one, you will get a black screen. You can find out which version your using in Control Panel -> System and Security -> System.

You could also make your script choose the correct one:

import struct
import ctypes

PATH = 'C:\\Users\\Patrick\\Desktop\\0200200220.jpg'
SPI_SETDESKWALLPAPER = 20

def is_64bit_windows():
    """Check if 64 bit Windows OS"""
    return struct.calcsize('P') * 8 == 64

def changeBG(path):
    """Change background depending on bit size"""
    if is_64bit_windows():
        ctypes.windll.user32.SystemParametersInfoW(SPI_SETDESKWALLPAPER, 0, PATH, 3)
    else:
        ctypes.windll.user32.SystemParametersInfoA(SPI_SETDESKWALLPAPER, 0, PATH, 3)

changeBG(PATH)

Update:

I've made an oversight with the above. As @Mark Tolonen demonstrated in the comments, it depends on ANSI and UNICODE path strings, not the OS type.

If you use the byte strings paths, such as b'C:\\Users\\Patrick\\Desktop\\0200200220.jpg', use:

ctypes.windll.user32.SystemParametersInfoA

Otherwise you can use this for normal unicode paths:

ctypes.windll.user32.SystemParametersInfoW

This is also highlighted better with argtypes in @Mark Tolonen's answer, and this other answer.

The real problem is not defining argtypes. The A version takes a byte string for the 3rd parameter, and the W version takes a Unicode string.You can use both A and W regardless of OS type, if you call them correctly. — Mark Tolonen, Dec 21 '18 at 17:49

score 3 · Answer 2 · answered Dec 21 '18 at 17:59

SystemParametersInfoA takes an ANSI string (bytes type in Python 3).

SystemParametersInfoW takes a Unicode string (str type in Python 3).

So use:

path = b'C:\\Users\\Patrick\\Desktop\\0200200220.jpg'
ctypes.windll.user32.SystemParametersInfoA(20, 0, path, 3)

or:

path = 'C:\\Users\\Patrick\\Desktop\\0200200220.jpg'
ctypes.windll.user32.SystemParametersInfoW(20, 0, path, 3)

You can set the argtypes to do parameter checking. The 3rd parameter is documented as LPVOID but you can be more specific for type checking:

from ctypes import *
windll.user32.SystemParametersInfoW.argtypes = c_uint,c_uint,c_wchar_p,c_uint
windll.user32.SystemParametersInfoA.argtypes = c_uint,c_uint,c_char_p,c_uint

Change Windows 10 background in Python 3

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