Q133256: HOWTO: How to Prevent Mainframe Window from Being ReSized

Article: Q133256
Product(s): Microsoft C Compiler
Version(s): winnt:2.0,2.1,2.2,4.0,4.1,4.2
Operating System(s): 
Keyword(s): kbMFC KbUIDesign kbVC kbWndw kbGrpDSMFCATL
Last Modified: 06-MAY-2001

-------------------------------------------------------------------------------
The information in this article applies to:

- The Microsoft Foundation Classes (MFC), used with:
   - Microsoft Visual C++ for Windows, 16-bit edition, versions 1.5, 1.51, 1.52 
   - Microsoft Visual C++, 32-bit Editions, versions 2.0, 2.1, 2.2, 4.0, 4.1 
   - Microsoft Visual C++, 32-bit Enterprise Edition, version 4.2 
   - Microsoft Visual C++, 32-bit Professional Edition, version 4.2 
-------------------------------------------------------------------------------

SUMMARY
=======

Adding the WS_THICKFRAME windows style allows a window to be re-sized. By
removing this from the Mainframe window's styles, you can prevent this window
from being resized. Further, the MINMAXINFO structure stores the maximum and
minimum tracking size of a window. The WM_GETMINMAXINFO message is sent to a
window when the size or position of that window is about to change. An
application can over-ride the handler for this message to set a window's default
minimum or maximum tracking size.

MORE INFORMATION
================

You can prevent the Mainframe window of an AppWizard-generated SDI application
from being resized by following these steps:

1. Modify the IDR_MAINFRAME menu to add a top-level menu item (F&reeze!)
  with an ID of ID_FREEZE.

2. Add a public Boolean data member (say, BOOL freezeState) to the CMainFrame
  class to keep track of the current state of the application. Initialize
  freezeState to FALSE in the constructor of the CMainFrame class.

3. Provide a command handler for the 'Freeze' menu item as follows:

     void CMainFrame::OnFreeze()
     {
        char* lpszFreeze = "F&reeze!";
        char* lpszUnFreeze = "&UnFreeze!";
        CMenu* pmenu = GetMenu();
        if (!freezeState)
        {

            freezeState = TRUE;
            pmenu->ModifyMenu(ID_FREEZE, MF_STRING, ID_FREEZE,
                                                         lpszUnFreeze);
            DWORD style = ::GetWindowLong(this->m_hWnd, GWL_STYLE);

     // Remove the thick frame style and the Minimize, Maximize buttons
          style &= ~(WS_MAXIMIZEBOX|WS_MINIMIZEBOX|WS_THICKFRAME);
          ::SetWindowLong(this->m_hWnd, GWL_STYLE, style);
     }
     else
     {
         freezeState = FALSE;
         pmenu->ModifyMenu(ID_FREEZE, MF_STRING, ID_FREEZE,
                                                        lpszFreeze);
         DWORD style = ::GetWindowLong(this->m_hWnd, GWL_STYLE);

     // Add the thick frame style and the Minimize, Maximize buttons
        style |= (WS_MAXIMIZEBOX|WS_MINIMIZEBOX|WS_THICKFRAME);
        ::SetWindowLong(this->m_hWnd, GWL_STYLE, style);
        }
        DrawMenuBar();
     }

4. Provide a handler for the WM_GETMINMAXINFO message as follows:

     void CMainFrame::OnGetMinMaxInfo(MINMAXINFO FAR* lpMMI)
     {
        if (freezeState)
        {
            RECT rc;

            GetWindowRect(&rc);
            lpMMI->ptMaxSize.x = rc.right - rc.left;
            lpMMI->ptMaxSize.y = rc.bottom - rc.top;
            lpMMI->ptMaxPosition.x = rc.left;
            lpMMI->ptMaxPosition.y = rc.top;
            lpMMI->ptMinTrackSize.x = rc.right - rc.left;
            lpMMI->ptMinTrackSize.y = rc.bottom - rc.top;
            lpMMI->ptMaxTrackSize.x = rc.right - rc.left;
            lpMMI->ptMaxTrackSize.y = rc.bottom - rc.top;
        }

        CFrameWnd::OnGetMinMaxInfo(lpMMI);
     }

5. If the mainframe is maximized, disable the Freeze menu option because there
  is no point in making the window non-resizable because a maximized window
  cannot be resized anyway:

     void CMainFrame::OnSize(UINT nType, int cx, int cy)
     {
        CFrameWnd::OnSize(nType, cx, cy);
        CMenu* pmenu = GetMenu();

        if (nType == SIZE_MAXIMIZED)
            pmenu->EnableMenuItem(ID_FREEZE, MF_DISABLED|MF_GRAYED);
        else
            pmenu->EnableMenuItem(ID_FREEZE, MF_ENABLED);

        DrawMenuBar();
     }

NOTE: The steps to prevent the Mainframe window of an MDI application from being
resized should be identical to the steps listed in this article. However,
because there is more than one menu resource in an MDI application, you may want
to design your application to add the 'Freeze' menu item to more than one menu
resource.

Additional query words: kbinf 1.50 2.00 2.10 2.20 2.50 2.51 2.52 3.00 3.0 3.10 3.1 3.20 3.2 4.00 4.10 4.20

======================================================================
Keywords          : kbMFC KbUIDesign kbVC kbWndw kbGrpDSMFCATL 
Technology        : kbAudDeveloper kbMFC
Version           : winnt:2.0,2.1,2.2,4.0,4.1,4.2
Issue type        : kbhowto

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1986-2002.