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I'm trying to get the text stored in the clipboard by just using ctypes in Python 3.6. I tested a lot of solutions I found on Stack and GitHub, but they only work for Python 2 to Python 3.4.

This is the code you'll find almost everywhere: 

from ctypes import *

def get_clipboard_text():
    text = ""
    if windll.user32.OpenClipboard(c_int(0)):
        h_clip_mem = windll.user32.GetClipboardData(1)
        windll.kernel32.GlobalLock.restype = c_char_p
        text = windll.kernel32.GlobalLock(c_int(h_clip_mem))
        windll.kernel32.GlobalUnlock(c_int(h_clip_mem))
        windll.user32.CloseClipboard()
    return text

I tested it in Python 3.4. It worked fine and returned the text in the clipboard. But running the same script on Python 3.6 always returns None. I could not find a solution for Python 3.6 so far.

I'm wondering if anybody could help me out since I don't know much about ctypes and C programming at all.

chrizator
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1 Answers1

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My guess is you are using 64-bit Python 3.6 so handles are 64-bit, and you are passing them as c_int (32-bit).

With ctypes, it is best to be explicit about all the arguments and return types. the following code should work on 32- and 64-bit Python 2 and 3.

Also, CF_UNICODETEXT will be able to handle any text you copy.

from __future__ import print_function
import ctypes
import ctypes.wintypes as w

CF_UNICODETEXT = 13

u32 = ctypes.WinDLL('user32')
k32 = ctypes.WinDLL('kernel32')

OpenClipboard = u32.OpenClipboard
OpenClipboard.argtypes = w.HWND,
OpenClipboard.restype = w.BOOL
GetClipboardData = u32.GetClipboardData
GetClipboardData.argtypes = w.UINT,
GetClipboardData.restype = w.HANDLE
GlobalLock = k32.GlobalLock
GlobalLock.argtypes = w.HGLOBAL,
GlobalLock.restype = w.LPVOID
GlobalUnlock = k32.GlobalUnlock
GlobalUnlock.argtypes = w.HGLOBAL,
GlobalUnlock.restype = w.BOOL
CloseClipboard = u32.CloseClipboard
CloseClipboard.argtypes = None
CloseClipboard.restype = w.BOOL

def get_clipboard_text():
    text = ""
    if OpenClipboard(None):
        h_clip_mem = GetClipboardData(CF_UNICODETEXT)
        text = ctypes.wstring_at(GlobalLock(h_clip_mem))
        GlobalUnlock(h_clip_mem)
        CloseClipboard()
    return text

print(get_clipboard_text())
Mark Tolonen
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  • Thank you very much, the code works perfectly! I did not think of 32-bit and 64-bit versions of python. – chrizator Sep 09 '17 at 18:51
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    @chrizator, kernel and window handles are 32-bit. But special handles for the latter that have a negative value must be sign extended to 64-bit. Also, some handles really are memory addresses such as `HMODULE` and `HGLOBAL`, as is obviously the result of `GlobalLock`. In practice, always declare `argtypes` and `restype` when working with handles and pointers to avoid hard coding implementation details and assumptions. – Eryk Sun Sep 09 '17 at 22:44
  • Thank you for clarifying. So by defining `argtypes` and `restypes` the code is working for 32 & 64 bit? Sorry for asking these stupid questions, but I am really new to this topic. – chrizator Sep 09 '17 at 23:34