Modal MFC frame window

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Introduction

Sometimes, it may be useful to have a modal window with Doc/View architecture, toolbars/statusbar support (i.e. base features implemented in MFC frame windows). How to get these without implementing all of these features in a CDialog-derived class? The CModalFrame utility class presented here helps you implement a modal dialog's behavior for any CFrameWnd-derived window class in an easy way.

If you have to use it and have a bit of time, please add a comment at the bottom of this page and tell, in which context you decided to use this code. I would be interested.

Background

Some basic facts:

• All required features are already implemented in CFrameWnd-derived classes.
• The basic support of modal message loop is already implemented in the CWnd class.

Brief implementation description:

1. The utility code uses only the CFrameWnd class interface and does not make any suggestions about the internal implementation details of any CFrameWnd-derived classes.
2. CModalFrame::Run creates an instance of the internal CModalDialogLock class which:
   • stores modal loop context,
   • runs modal message loop and,
   • supports multiple running modal frames.
3. CModalDialogLock subclasses the created frame window to provide:
   • update command UI for the frame on WM_KICKIDLE message,
   • exit from modal message loop on WM_NCDESTROY message and,
   • restore standard modal window behavior on WM_NCACTIVATE message.
4. You should not use WS_CHILD window style for a frame. Because its parent window is disabled during modal loop. So child frame window also will be disabled (for example, MDI child frame)!

Using the code

• Files needed:
  • ModalFrame.h
  • ModalFrame.cpp

Sample of usage:

void CMyView::OnRunModalFrame()
{
    CCreateContext context;
    context.m_pNewViewClass = RUNTIME_CLASS(CMyOtherView);
    context.m_pCurrentDoc = GetDocument();
    context.m_pNewDocTemplate = GetDocument()->GetTemplate();
    context.m_pLastView = this;
    context.m_pCurrentFrame = GetParentFrame();

    CRuntimeClass * pFrameClass = RUNTIME_CLASS(CMyModalFrame);

    if (!CModalFrame::Run(*pFrameClass, false, IDR_MYFRAMERESOURCE,
                          WS_OVERLAPPEDWINDOW | 
                          FWS_ADDTOTITLE, this, &context))
    {
        AfxMessageBox(AFX_IDP_COMMAND_FAILURE);
    }
}

// don't forget close modal frame like a modal dialog box!
void CMyModalFrame::OnClose()
{
    int nModalResult = -1;
    CModalFrame::End(this, nModalResult);
}

See demo project code for more details.

History

• Version 1.2
  • Bug fixing.
  • More accurate work with a stack of modal frames.
• Version 1.1
  • Implemented support for multiple running modal frames.
  • More accurate restoring active window after the end of the modal message loop.
• Version 1.0
  • Initial version.

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)