The slowest process related function in the world

[SFSxOI]

While searching through the forums today for something I saw a question posted in a thread from 2003 (http://www.purebasic.fr/english/viewtop ... t=testhwnd) about retrieving a window handle from a processID. The question also involved some VB code, the VB code is:

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Function InstanceToWnd(ByVal target_pid As Long) As Long
    Dim test_hwnd As Long, test_pid As Long, test_thread_id As Long
    'Find the first window
    test_hwnd = FindWindow(ByVal 0&, ByVal 0&)
    Do While test_hwnd <> 0
        'Check if the window isn't a child
        If GetParent(test_hwnd) = 0 Then
            'Get the window's thread
            test_thread_id = GetWindowThreadProcessId(test_hwnd, test_pid)
            If test_pid = target_pid Then
                InstanceToWnd = test_hwnd
                Exit Do
            End If
        End If
        'retrieve the next window
        test_hwnd = GetWindow(test_hwnd, #GW_HWNDNEXT)
    Loop
End Function
Private

Anyway, I got curious if it would work in PB so I did this real quick:

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Global test_hwnd.l, test_pid.l, test_thread_id.l

Procedure InstanceToWnd(target_pid.l)
; Dim test_hwnd.l
; Dim test_pid.l
; Dim test_thread_id.l

;Find the first window
test_hwnd = FindWindow_(0,0)

While test_hwnd <> 0
  ;Check If the window isn't a child
        If GetParent_(test_hwnd) = 0 ;Then
          ;Get the window's thread
            test_thread_id = GetWindowThreadProcessId_(test_hwnd, test_pid)
              If test_pid = target_pid ;Then
                InstanceToWnd = test_hwnd
                Break ;Exit Do
              EndIf
        EndIf
        ;retrieve the Next window
        test_hwnd = GetWindow_(test_hwnd, GW_HWNDNEXT)
Wend

ProcedureReturn test_hwnd

EndProcedure

I fed it a PID with a quick droopy lib function with a

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Debug InstanceToWnd(GetPidProcess("notepad.exe"))

(BTW, the above will always return 0, although i understand that in VB it actually returns something)

This has got to be one of the slowest things in the world, I had time to make a picture of iced tea and a sandwich before it finished. Anyway, it begs the question as to how to retrieve a window handle from a processID when all you know is the processID. So if you have the processID and nothing else (no window titles or anything and its not a window you made), how can you get the hWnd in a painless way from the processID (I know there can be many processes associated with an executable - maybe this is why it would be difficult?). Seems difficult if not impossible to do, I guess you could enum everything but this takes time too. Any one have any ideas?

[Pupil]

Maybe you could change the following line:

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test_thread_id = GetWindowThreadProcessId_(test_hwnd, test_pid)

To this instead:

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test_thread_id = GetWindowThreadProcessId_(test_hwnd, @test_pid)

Because the test following this line is rather useless if you don't have a proper return value to test against..

[SFSxOI]

Thanks Pupil;

That did the trick! Duh! I hadn't even noticed that. Thank You

It works. However, if an application is running more then one thread (explorer for example) then it grabs something else and maybe not return the hWnd you expect (which is what I expected it to do with things that run multiple threads), the handle of the first thread i it finds for that PID I guess, maybe, don't know. But for things that only run a single thread it returns the correct window handle.