Re: Why does this TextOut() sometimes hang up?

From:

"Peter Olcott" <NoSpam@SeeScreen.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Wed, 9 May 2007 23:22:21 -0500

Message-ID:

<%5x0i.149565$2Q1.103859@newsfe16.lga>

"Joseph M. Newcomer" <newcomer@flounder.com> wrote in
message news:jbv443ljs188hnspe0ha1h71cv4gj0mc41@4ax.com...

Any time you put this kind of code in, it is screaming
"this should have been a thread!"
Such gross hacks were required in Win16, but they should
be avoided in Win32.
joe

It just occurred to me that this sort of advice (about
multi-threading) has recently taken on much more
significance with multi-processor machines becoming the
norm. I would estimate that it would be pretty easy for the
OS to allocate a thread to a separate processor, once the
programmer has divided up the processing into separate
threads.

On Wed, 9 May 2007 17:46:18 -0500, "Peter Olcott"
<NoSpam@SeeScreen.com> wrote:

"Mark Salsbery" <MarkSalsbery@discussions.microsoft.com>
wrote in message
news:03D471C4-281F-403A-A60B-A67459BF1AE9@microsoft.com...

I should have read the code more closely :)

Maybe you need to pump messages in the loop if it's on
the
same thread as
the window's UI thread.

//An example message pump. Call periodically in your
loop.
MSG msg;
while ( ::PeekMessage( &msg, NULL, 0, 0, PM_NOREMOVE ) )
{
  if ( !AfxGetApp()->PumpMessage( ) )
  {
     break;
  }
}

I stuck the above code in a function called PumpMessages()
and it solved my problem, thanks!

"Peter Olcott" wrote:

"Mark Salsbery"
<MarkSalsbery@discussions.microsoft.com>
wrote in message
news:E603B544-517C-4595-B222-BD6364F7792A@microsoft.com...

Are you painting over the top of your drawn text?

Besides the TextOut() in the loop you may need to
redraw
the same text in
response to WM_PAINT (OnPaint()) to make sure it's
redrawn
when the window
is repainted as well as in the loop.

Mark

I am using the basic double buffering method that
paints
a
memory DC to the screen.

"Peter Olcott" wrote:

I tried to make the equivalent of a simple
ProgressBar
by
displaying a count in the window of the outermost
one
of
several nested loops. This process is very CPU
intensive
so
I have to force screen updates. The count works
correctly
unless I move the window, and then the window is no
longer
updated. What is causing this, and how can I fix it?

// The TextOut() display code inside a very tight
loop
    ClientArea.TextOut(0, 0, String,
strlen(String));
    MainWin->InvalidateRect(NULL);
    MainWin->UpdateWindow();

// Window member data
  CDC ClientArea; // virtual window device
context
  CBitmap m_bmp; // virtual window bitmap

// Window Constructor
MainWindow::MainWindow()
{
  ScreenWidth = GetSystemMetrics(SM_CXSCREEN);
  ScreenHeight = GetSystemMetrics(SM_CYSCREEN);
  Create(NULL, "SeeScreen the Screen Recognizer",
WS_OVERLAPPEDWINDOW | WS_HSCROLL | WS_VSCROLL,
rectDefault,
NULL, "TextMenu");
  CClientDC DC(this);

  // Create bitmap for virtual window
  ClientArea.CreateCompatibleDC(&DC);
  m_bmp.CreateCompatibleBitmap(&DC, ScreenWidth,
ScreenHeight);
  ClientArea.SelectObject(&m_bmp);

  // use standard background
  MainBrush.CreateStockObject(WHITE_BRUSH);
  ClientArea.SelectObject(&MainBrush);

  // paint background of virtual window
  ClientArea.PatBlt(0, 0, ScreenWidth, ScreenHeight,
PATCOPY);
}

// Update screen using contents of virtual window.
afx_msg void MainWindow::OnPaint()
{
  CPaintDC DC(this);
  DC.BitBlt(0, 0, ScreenWidth, ScreenHeight,
&ClientArea,
0,
0, SRCCOPY);
}

Joseph M. Newcomer [MVP]
email: newcomer@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm