Re: Strange problem with "On-Screen Keyboard" and CreateProcess

From:
Tom Becker <Tom_dot_Becker_at_Ziemann_minus_Urban_dot_de>
Newsgroups:
microsoft.public.vc.mfc
Date:
Wed, 25 Jun 2008 10:42:47 +0200
Message-ID:
<OCtYj$p1IHA.1628@TK2MSFTNGP03.phx.gbl>
David Ching schrieb:

"Tom Becker" <Tom_dot_Becker_at_Ziemann_minus_Urban_dot_de> wrote in message
news:uzGsNef1IHA.5728@TK2MSFTNGP06.phx.gbl...

Hallo

In my application (MFC MDI) I want to display an "On-Screen Keyboard".
As WinXP has one on board (osk.exe), I've decided to use this one.

This is the way I do it:

PROCESS_INFORMATION pI;
STARTUPINFO sI;

memset(&sI, 0, sizeof(sI));
sI.cb = sizeof STARTUPINFO;

if(!CreateProcess(NULL, m_oskPath, NULL, NULL, FALSE, 0, NULL, NULL, &sI,
&pI))
{
//Display Error
SysErrMsgBox(GetLastError());
}
else
{
//Do something with the keyboard
...

//Either use the hard way
//::TerminateProcess(pI.hProcess, 0);

//OR maybe a better solution
//BTW. WM_CLOSE does not work. osk.exe remains active
::PostThreadMessage(pI.dwThreadId, WM_QUIT, 0, 0);

DWORD exitCode = STILL_ACTIVE;
do
{
Sleep(0);
if(!GetExitCodeProcess(pI.hProcess, &exitCode))
{
//Display error
SysErrMsgBox(GetLastError());

break;
}
}
while(exitCode == STILL_ACTIVE);
}

This works nearly perfect.
My problem is another process created by osk.exe. The name is
"msswchx.exe"
This process remains active after closing osk.exe with one of the two
above
described solutions. It does not matter which of the solutions I take.
Even worse, everytime I start a new instance of osk, a new instance of
"msswchx.exe"
is created and remains in memory.

Can anyone tell me how to solve this?

When I close osk.exe manually by pressing the Close-Button both processes
are terminated.


Tom, try posting WM_SYSCOMMAND with SC_CLOSE to simulate clicking the 'X' in
the osk caption. But don't do a PostThreadMessage(), which can fail if the
thread has created windows. Instead, iterate the top level windows of the
osk.exe process using EnumThreadWindows (the thread you want is
pi.dwThreadId) and post this to each of them.

Another thing: when waiting for the osk.exe process to terminate, do a
WaitForSingleObject(pi.hProcess) instead of polling the exit code. Far
better. And don't forget to CloseHandle() the handles in pi (pi.hProcess
and pi.hThread).

-- David


Thanks. That did the trick.
I've tried EnumThreadWindows() before, but only send a WM_CLOSE instead of
WM_SYSCOMMAND with SC_CLOSE.

WaitForSingleObject() is the better solution.
I also forgot calling CloseHandle() although it is clearly documented :-(

Tom

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