Re: Dialog based application and generated OnPaint for the dialog class

From:

Eric Lilja <mindcoolerremoveme@gmail.com>

Newsgroups:

microsoft.public.vc.mfc

Date:

Mon, 06 Aug 2007 19:26:55 +0200

Message-ID:

<unzM#7E2HHA.5772@TK2MSFTNGP02.phx.gbl>

Tom Serface wrote:

I think this is saying that if you had used a doc/view (SDI or MDI)
paradigm from the wizard the framework would do it for you. Since you
have a dialog application you have to do it yourself (thus they provide
the code for you).

Yes, but I wrote that I have a minimize button on my dialog but if I
comment out the OnPaint I still get an icon. I see no visual difference.
So it seems that the generated code is in fact not relevant for my
project and that's what I wanted comments on. Seems odd if the appwizard
redefines methods when there's no reason to. Thanks for replying.

Tom

"Eric Lilja" <mindcoolerremoveme@gmail.com> wrote in message
news:eLAA1vD2HHA.3760@TK2MSFTNGP03.phx.gbl...

Hello, I'm using MSVC++ 8.0 SP1 and I created a dialog based MFC
application using the application wizard. In my CDialog-derived class,
MyDialog, the appwizard generated the following OnPaint() for me:

// If you add a minimize button to your dialog, you will need the code
below
// to draw the icon. For MFC applications using the document/view model,
// this is automatically done for you by the framework.
void
MyDialog::OnPaint()
{
   if (IsIconic())
   {
      CPaintDC dc(this); // device context for painting

      SendMessage(WM_ICONERASEBKGND,
reinterpret_cast<WPARAM>(dc.GetSafeHdc()), 0);

      // Center icon in client rectangle
      int cxIcon = GetSystemMetrics(SM_CXICON);
      int cyIcon = GetSystemMetrics(SM_CYICON);
      CRect rect;
      GetClientRect(&rect);
      int x = (rect.Width() - cxIcon + 1) / 2;
      int y = (rect.Height() - cyIcon + 1) / 2;

      // Draw the icon
      dc.DrawIcon(x, y, m_hIcon);
   }
   else
   {
      CDialog::OnPaint();
   }
}

The comment says that I need this to display an icon if I decide to
add a minimize button to my dialog if I'm not using docview. Well, I
added a minimize button and commented everything up to and including
the else-statement out, and it displays the icon just fine. But I
don't have a document or a view class and I don't recall making any
particular choices about that when I went through the appwizard.

So it seems I have a framework support application even though I have
no view or document class and that means I don't have to redefine
OnPaint() as far as displaying an icon for a dialog with a minimize
box is concerned, is that right? I'd like to remove this OnPaint() if
I don't need it. No use doing something that the framework is already
taking care of.

- Eric