Re: message queues and buffered mouse clicks

From:

"Tom Serface" <tserface@msn.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Mon, 5 Jun 2006 10:30:45 -0700

Message-ID:

<OMU8IXMiGHA.1260@TK2MSFTNGP05.phx.gbl>

You could do the query in a thread as Joe suggests or you could simply do a
short sleep before starting the query to allow messages to get done. I
typically put a static variable in the routine at the top:

static bool bBusy = false;

if(bBusy)
return; // Already doing something in here

bBusy = true;
Sleep(500); // Wait a half a second before doing query (less time would
probably work as well).

// Do stuff

bBusy = false; // Done
return;

That way if it comes in a subsequent time while you are still working it
would simply ignore that second call. I'm not sure this will solve your
immediate problem, but it's worth a try.

Tom

"mfc130603" <mfc130603.28su5x@mail.codecomments.com> wrote in message
news:mfc130603.28su5x@mail.codecomments.com...

Hi,

I have a button in an MFC app that executes a lengthy query and I want
to disable the button while the query executes. The problem is that
mouse clicks over the disabled button are buffered, and are then
processed when the button is enabled. Here's my OnBnClickedQueryButton
handler.

Attempt 1:
m_queryButton.EnableWindow(FALSE);
ExecuteLengthyQuery();
m_queryButton.EnableWindow();

So I tried to grab the focus away from the button, but this attempt
didn't work either.

Attempt 2:
SetFocus();
SetCapture();
m_queryButton.EnableWindow(FALSE);

ExecuteLengthyQuery();

m_queryButton.EnableWindow();
ReleaseCapture();

Finally, I rationalized that mouse click messages were being queued up
in the message queue, so I had to allow them to process without
invoking ExecuteLengthyQuery. I modified my OnBnClickedQueryButton
handler again.

Attempt 3:

if (m_buttonLockout)
{
return;
}

m_buttonLockout = true;
ExecuteLengthyQuery();

HWND myHWND = GetSafeHwnd();
::PostMessage(myHWND, WM_FINISHED_QUERY, 0, 0);

I reset buttonLockout to false in the WM_FINISHED_QUERY message
handler, with the idea that my WM_FINISHED_QUERY message was posted to
the message queue after the WM_LBUTTONDOWN messages. But guess what?
Didn't work. Then I combined Attempts 2 and 3, and it still didn't
work!

Can someone please shed some light on this behavior?

Thank you,
Jim

--
mfc130603
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