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Create a modeless dialog box as sibling of the app's main window

, 9 Nov 2000
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Simple step by step article explaining how to create a modeless dialog box as sibling of the app's main window.

This article is part of the drag and drop interface samples.

  1. Serializing ASCII Data
  2. Modeless child dialog
  3. Modeless sibling dialog
  4. The drag source
  5. The MFC drop target
  6. The TBTextTarget class

  • Download source files - 20 Kb

    It's nearly as short as the child version of modeless dialogs

    Follow these steps:

    1. Create a new dialog resource and use the Class Wizard for making a new CDialog based class COtherDropDialog
    2. In the class maintaining the modeless dialog (here it's CInterfaceView) add a member variable of type pointer to CWinThread and make sure you have a destructor:
      <font color="#000080">class</font> CInterfaceView : public CView
      {
      ...
          CWinThread *m_pDlgThread
          ~CInterfaceView();
      ...
      }
    3. Use ClassWizard to create a new CWinThread-based class COtherDropDialogThread
    4. Override COtherRopDialogThread::InitInstance():
      If you forget to change the m_pMainWnd variable, the dialog will stay modal!
      BOOL COtherDropDialogThread::InitInstance()
      {
          COtherDropDialog dlg;
      
          m_pMainWnd = &dlg;
          dlg.DoModal();  <font color="#008000">// returning false will make MFC doing the cleanup for us :)</font>
                
          return FALSE;
      }
    5. In your appropriate message handler, do the following:
      <FONT COLOR=#008080>void</FONT> CInterfaceView::OnFileOthermodeless() 
      {
          <FONT COLOR=#008000>// this block determines if we have our dialog already</FONT>
          <FONT COLOR=#008000>// displayed and not yet closed. You can't rely on </FONT>
          <FONT COLOR=#008000>// m_pDlgThread to be NULL, because if you already have displayed </FONT>
          <FONT COLOR=#008000>// and closed it, the pointer is not NULL but invalid	 </FONT>
          <FONT COLOR=#804040>if</FONT> (AfxIsValidAddress(m_pDlgThread, <FONT COLOR=#804040>sizeof</FONT>(CWinThread)) &&
              AfxIsValidAddress(m_pDlgThread->m_pMainWnd, <FONT COLOR=#804040>sizeof</FONT>(CWnd)))
          {
              <FONT COLOR=#804040>if</FONT> (::IsWindow(m_pDlgThread->m_pMainWnd->GetSafeHwnd()))
              {    m_pDlgThread->GetMainWnd()->SetWindowPos(
      	                &wndTop, <FONT COLOR=#aa6400>0</FONT>,<FONT COLOR=#aa6400>0</FONT>,<FONT COLOR=#aa6400>0</FONT>,<FONT COLOR=#aa6400>0</FONT>,SWP_NOMOVE|SWP_NOSIZE|SWP_SHOWWINDOW);
                   <FONT COLOR=#804040>return</FONT>;
              }
          }
          <FONT COLOR=#008000>// OK, we need to create a new thread</FONT>
          m_pDlgThread=AfxBeginThread( RUNTIME_CLASS(COtherDropDialogThread) );	
      }
      
      
    6. If you like your top-level window to have an icon displayed in the taskbar, add the following to COtherDropDialog:: OnInitDialog (ommited in the sample):
      BOOL COtherDropDialog::OnInitDialog() 
      {
          CDialog::OnInitDialog();
          m_hIcon = AfxGetApp()->LoadIcon(IDI_MYICON);
          SetIcon(m_hIcon, TRUE);
          SetIcon(m_hIcon, FALSE);
      <font color="#008000">    // and all the other stuff
          //...
      </font>}
    7. Don't forget to do the clean-up in the destructor:
      CInterfaceView::~CInterfaceView()
      {
          <font color="#000080">if</font> (AfxIsValidAddress(m_pDlgThread, <font color="#000080">sizeof</font>(CWinThread)) &&
      	AfxIsValidAddress(m_pDlgThread->m_pMainWnd, <font color="#000080">sizeof</font>(CWnd)))
          {
      	// retrieve the threads main window
      	CDialog *pDlg = (CDialog *)m_pDlgThread->m_pMainWnd;
      
      	<font color="#000080">if</font> (::IsWindow(pDlg->GetSafeHwnd()))
      	{
      <font color="#008000">	    // make sure we have a CDialog-derived main 
      	    // thread window then terminate it
      </font>	    ASSERT(pDlg->IsKindOf(RUNTIME_CLASS(CDialog)));
      	    pDlg->EndDialog(IDCANCEL);
      
      <font color="#008000">	    // now give the thread some time to end, 
      	    // 2 second should be enough. You may 
      	    // able to use INFINITE as wait value, if you dare...
      </font>	    WaitForSingleObject(m_pDlgThread->m_hThread, 2000);
      	    m_pDlgThread=NULL;
      	}
          }
      }
  • License

    This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

    A list of licenses authors might use can be found here

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    About the Author

    Thomas Blenkers
    Web Developer
    Germany Germany
    PhD Chemist,
    programming with MSVC & MFC since 1996

    Comments and Discussions

     
    QuestionHow you can add a modeless dialog to a win32 project PinmemberMember 100432902-Jul-14 23:10 
    GeneralSystem crashes Pinmemberken12325-Apr-05 9:00 
    Generalprobelm with CPU usage PinsussAnonymous14-Apr-03 20:50 

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