MFC - execute code right after dialog is shown (.NET equivalent of Form.Shown)

I'm doing some small changes to C++ MFC project. I'm .NET developer so Windows programming is new to me.

I need to launch some method right after CDialog is completely shown (painted) for the first time, but only once.

How can I do this? In .NET I would handle Form.Shown event.

Do I need to handle some message? Which? Do I need to override some CDialog method? Or is there no easy way? I'm thinking of handling WM_ACTIVATE and then using a flag to ensure I call another method only once.

From stackoverflow

• Found the answer here: Waiting until the dialog box is displayed before doing something

  Short story:
  INT_PTR CALLBACK
  DlgProc(HWND hwnd, UINT uiMsg, WPARAM wParam, LPARAM lParam)
  {
    switch (uiMsg) {
  
    case WM_INITDIALOG:
      return TRUE;
  
    case WM_WINDOWPOSCHANGED:
      if ((((WINDOWPOS*)lParam)->flags & SWP_SHOWWINDOW) &&
          !g_fShown) {
        g_fShown = TRUE;
        PostMessage(hwnd, WM_APP, 0, 0);
      }
      break;
  
  
    case WM_APP:
        MessageBox(hwnd,
                   IsWindowVisible(hwnd) ? TEXT("Visible")
                                         : TEXT("Not Visible"),
                   TEXT("Title"), MB_OK);
        break;
  
    case WM_CLOSE:
     EndDialog(hwnd, 0);
     break;
    }
  
    return FALSE;
  }
  

  If you're using MFC like I am you'll need to map WM_WINDOWPOSCHANGED and then use ON_MESSAGE to map WM_APP. See this CodeProject article for more details.

• Another approach I've used a number of times with great success is to use a timer. Set it for 10m0s. It'll only fire after the dialog is shown.

  Ornus : Timer might not fire in certain conditions. Article I'm refering to (http://blogs.msdn.com/oldnewthing/archive/2006/09/25/770536.aspx) covers that.

• Joel,

  Timer is not guaranteed to fire after painting. WM_PAINT message has the lowest priority. If for some unusual reason, the 10ms elapsed before the WM_PAINT message had a chance to be processed (e.g. long processing in WM_INITDIALOG), OnTimer() will fire before OnPaint().

• Hell put the code in OnPaint() and thow a bool m_fullyInitilized in your class. I like the timer too.. Though I usually go with 100ms. I also move all my initilization code out of the oninit, in these cases.. Just to protect against too much processing in there.