UDF for detecting whether AutoIt can cut-paste from a window

[tcurran]

Here's a short UDF that will, at least in most cases, detect whether a window can be copied from or pasted to programmatically--for example, by Send()ing ctl-c, ctl-v. This is often disabled when programs (like your AutoIt script) run at a lower UAC integrity level than the application they are trying to operate on.

#include <WinAPI.au3>

Func _WindowIsPasteable($handle) ;accepts window handle; returns true or false whether a window will accept Ctl-C, Ctl-V
    Local $bCanPaste = True
    Local $hTestWindowPID = 0
    Local $hTestWindowTID = _WinAPI_GetWindowThreadProcessId($handle, $hTestWindowPID)
    _WinAPI_AttachThreadInput(_WinAPI_GetCurrentThreadId(), $hTestWindowTID, True);attach to window we want to paste into
    $bCanPaste = _WinAPI_GetFocus() ;Test whether window is paste-able--returns False if it is not
    _WinAPI_AttachThreadInput(_WinAPI_GetCurrentThreadId, $hTestWindowTID, False);detach from window thread
    Return $bCanPaste
EndFunc

Pass it a window handle; it returns true or false whether a window will accept programmatic pasting. The function may not work on the CMD window, since it handles the clipboard uniquely.

This function works by attaching to the program thread of the window whose handle it receives, then attempting to perform a GetFocus on that thread. In most cases, the attempt will fail if the window will not accept programmatic copy-paste.

Edited May 9, 2017 by tcurran

[qwert]

Thanks for this.  I hadn't considered such a method.  But I do have a question:

Quote

the attempt will fail if the window will not accept programmatic copy-paste

Can you point to documentation that explains this in more detail?  Are there cases where a browser window, for example, would return False (='no paste')?

[tcurran]

qwert--

Those are excellent questions. This approach was suggested to me by "Joe" the developer of ArsClip. I adapted his approach to AutoIT, tested it in my particular application (it worked!!) and posted it here.

Your question about browser windows is particularly trenchant, but--since I haven't tested it--I have no answer. Please post back here if you learn whether it does or doesn't work.