Re: Drawing disappears when window dragged

From:
"David Ching" <dc@remove-this.dcsoft.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Sat, 17 Feb 2007 08:22:19 -0800
Message-ID:
<sXFBh.59141$QU1.40454@newssvr22.news.prodigy.net>
"zaku_so" <zakuso@discussions.microsoft.com> wrote in message
news:A9520AFD-C2A4-48E0-91FF-34074028351A@microsoft.com...

Thanks.
But now the drawings flash once and disappear.
I moved the code for drawing to after CDialog::OnPaint().

Originally the drawing region is a static picture rectangle.
After I changed the type to frame, flashing does not occur anymore.
What's the reason behind? Is that the solid rectangle is drawn after my
drawings, so that they are covered immediately?

void CPiezoDlg::OnPaint()
{

if (IsIconic())
{
CPaintDC dc(this); // device context for painting
                               ...
}
else
{
CDialog::OnPaint();
//Moved codes for drawing here
}
}


Don't call CDialog::OnPaint(). OnPaint() is one override you're not
supposed to call the base class. That's because CPaintDC() needs to be used
exactly one time, since it calls BeginPaint/EndPaint. Therefore, rewrite
the code:

void CPiezoDlg::OnPaint()
{
   CPaintDC dc(this); // device context for painting

    if (IsIconic())
    {
            ...
    }
    else
    {
       //Moved codes for drawing here
    }
}

-- David (MVP)

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