Copy PIL/PILLOW Image to Windows Clipboard

Question

I've seen this question and i followed every step, changing the code to satisfy my requirements, that are Python3, Pillow, and ctypes. The less libraries, the better.

import ctypes
from PIL import ImageGrab, Image
from io import BytesIO

user32 = ctypes.windll.user32

img = ImageGrab.grab()
output = BytesIO()
img.convert("RGB").save(output, "BMP")
data = output.getvalue()[14:]
output.close()

user32.OpenClipboard()
user32.EmptyClipboard()
user32.SetClipboardData(user32.CF_DIB, data)
user32.CloseClipboard()

That is the stripped code from my script that, i think, is the same code in the question ported to my requirements. When executed, it should copy the current desktop to the clipboard. I get this instead:

File "C:\Users\Gcq\Documents\python\Screen\Screen.py", line 132, in shot
    user32.OpenClipboard()
ValueError: Procedure probably called with not enough arguments (4 bytes missing)

I'm sorry i'm asking such a (probably) easy question here, but i really don't know what is failing, and ctypes is not my thing.

Answer 1

Whew. Apparently the win32clipboard library does simplify some things when compared to ctypes. Your attempt to simply replace one with the other is far from correct.

So I booted up my Windows virtual machine, installed Pillow and rewrote your program, learning from two other answers:

import io

import ctypes
msvcrt = ctypes.cdll.msvcrt
kernel32 = ctypes.windll.kernel32
user32 = ctypes.windll.user32

from PIL import ImageGrab

img = ImageGrab.grab()
output = io.BytesIO()
img.convert('RGB').save(output, 'BMP')
data = output.getvalue()[14:]
output.close()

CF_DIB = 8
GMEM_MOVEABLE = 0x0002

global_mem = kernel32.GlobalAlloc(GMEM_MOVEABLE, len(data))
global_data = kernel32.GlobalLock(global_mem)
msvcrt.memcpy(ctypes.c_char_p(global_data), data, len(data))
kernel32.GlobalUnlock(global_mem)
user32.OpenClipboard(None)
user32.EmptyClipboard()
user32.SetClipboardData(CF_DIB, global_mem)
user32.CloseClipboard()

Answer 2

The example uses pywin32, which is Python wrapper around Win32 API that hides some low level details you need to take care yourself of if you want to use ctypes.

Here is how you do it using ctypes, it adds a functionally of creating globally allocated buffer and copy the data into that buffer:

#!python

from PIL import Image
#from cStringIO import StringIO
from io import BytesIO
from ctypes import *
from ctypes.wintypes import *

HGLOBAL = HANDLE
SIZE_T = c_size_t
GHND = 0x0042
GMEM_SHARE = 0x2000

GlobalAlloc = windll.kernel32.GlobalAlloc
GlobalAlloc.restype = HGLOBAL
GlobalAlloc.argtypes = [UINT, SIZE_T]

GlobalLock = windll.kernel32.GlobalLock
GlobalLock.restype = LPVOID
GlobalLock.argtypes = [HGLOBAL]

GlobalUnlock = windll.kernel32.GlobalUnlock
GlobalUnlock.restype = BOOL
GlobalUnlock.argtypes = [HGLOBAL]

CF_DIB = 8

OpenClipboard = windll.user32.OpenClipboard
OpenClipboard.restype = BOOL 
OpenClipboard.argtypes = [HWND]

EmptyClipboard = windll.user32.EmptyClipboard
EmptyClipboard.restype = BOOL
EmptyClipboard.argtypes = None

SetClipboardData = windll.user32.SetClipboardData
SetClipboardData.restype = HANDLE
SetClipboardData.argtypes = [UINT, HANDLE]

CloseClipboard = windll.user32.CloseClipboard
CloseClipboard.restype = BOOL
CloseClipboard.argtypes = None

#################################################

image = Image.new("RGB", (200, 200), (255, 0, 0))

#output = StringIO()
output = BytesIO()
image.convert("RGB").save(output, "BMP")
data = output.getvalue()[14:]
output.close()

hData = GlobalAlloc(GHND | GMEM_SHARE, len(data))
pData = GlobalLock(hData)
memmove(pData, data, len(data))
GlobalUnlock(hData)

OpenClipboard(None)
EmptyClipboard()
SetClipboardData(CF_DIB, pData)
CloseClipboard()