SAMPLE: EditGrid.exe: Edit Cells in MSFlexGrid ActiveX Control

• The Microsoft Foundation Classes (MFC), included with:
  • Microsoft Visual C++, 32-bit Editions, version 5.0

SUMMARY

The Microsoft Flex Grid Control (MSFlexGrid), which ships with Visual C++ and Visual Basic, does not support editing of individual cells.

The Visual Basic Programmer's Guide has an example that shows how to programmatically add this functionality by placing a TextBox control over the cell to be edited, and then updating the cell programmatically.

EditGrid.exe is a sample that shows the steps needed to implement this feature in Microsoft Visual C++ using MFC.

MORE INFORMATION

The following file is available for download from the Microsoft Software Library:

~ EditGrid.exe

Q119591 How to Obtain Microsoft Support Files from Online Services

Steps to Add Editing Support to MSFlexGrid

1. Use the Component Gallery to add the MSFlexGrid to your project. This creates MFC based wrapper classes for the control.



2. Use ClassWizard to create a new generic CWnd-derived class named CEditGrid. After you create this class, change it so it is derived from the MSFlexGrid class. See the REFERENCES section of this article for more information.



3. Use ClassWizard to create a new CEdit-derived class named CEditWnd. Handle the WM_CHAR and WM_KEYDOWN messages:

   
         void CEditWnd::OnChar(UINT nChar, UINT nRepCnt, UINT nFlags)
         {
            if (nChar != 13) // Ignore ENTER key.
               CEdit::OnChar(nChar, nRepCnt, nFlags);
         }
   
         void CEditWnd::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
         {
            if (nChar == 27) // Esc means "Cancel".
            {
               SetWindowText("");
               ShowWindow(SW_HIDE);
               GetParent()->SetFocus();
            }
            else if (nChar == 13)  // Enter means "OK".
               GetParent()->SetFocus();
   
            CEdit::OnKeyDown(nChar, nRepCnt, nFlags);
         } 




4. Add the following member variables to CEditGrid:

   
         public:
            CEditWnd m_edit;
            long m_lBorderWidth;
            long m_lBorderHeight;
   
            int m_nLogX;
            int m_nLogY; 




5. Override the PreSubclassWindow() virtual function for CEditGrid:

   
         void CEditGrid::PreSubclassWindow()
         {
            // Calculate border size.
            SetRow(0);
            SetCol(0);
            m_lBorderWidth = GetCellLeft();
            m_lBorderHeigth = GetCellTop();
   
            // To convert grid rect from twips to DC units you need
            // pixels per inch.
            CDC* pDC = GetDC();
            m_nLogX = pDC->GetDeviceCaps(LOGPIXELSX);
            m_nLogY = pDC->GetDeviceCaps(LOGPIXELSY);
            ReleaseDC(pDC);
   
            // Create invisible edit control.
            m_edit.Create(WS_CHILD|ES_MULTILINE|ES_WANTRETURN,
               CRect(0,0,0,0), this, GetDlgCtrlID());
         } 




6. Handle the KeyPress, DBLClick, and LeaveCell reflected events in CEditGrid. To do this, you need to add an event map to the class:

   
      EditGrid.h
   
         protected:
            afx_msg void OnKeyPressGrid(short FAR* KeyAscii);
            afx_msg void OnDblClickGrid();
            afx_msg void OnUpdateGrid();
            DECLARE_EVENTSINK_MAP()
   
      EdtGrid.cpp
   
         BEGIN_EVENTSINK_MAP(CEditGrid, CMSFlexGrid)
         // {{AFX_EVENTSINK_MAP(CEditGrid)
         // }}AFX_EVENTSINK_MAP
            ON_EVENT_REFLECT(CEditGrid, -603 /* KeyPress */, OnKeyPressGrid,
                             VTS_PI2)
            ON_EVENT_REFLECT(CEditGrid, -601 /* DblClick */, OnDblClickGrid,
                             VTS_NONE)
            ON_EVENT_REFLECT(CEditGrid, 72 /* LeaveCell */, OnUpdateGrid,
                             VTS_NONE)
         END_EVENTSINK_MAP()
   
         void CEditGrid::OnDblClickGrid()
         {
            short i = 13;
            OnKeyPressGrid(&i); // Simulate a return.
         }
   
         void CEditGrid::OnKeyPressGrid(short FAR* KeyAscii)
         {
   
            ASSERT (KeyAscii != NULL);
   
            m_edit.SetWindowText(GetText());
   
            if (*KeyAscii == 13)
               m_edit.SetSel(0,-1);
            else
            {
               char buf[] = " ";
               buf[0] = (char)*KeyAscii;
               m_edit.SetSel(-1,-1);
               m_edit.ReplaceSel(buf);
            }
   
            // Adjust for border height and convert from twips to screen
            // units.
            m_edit.MoveWindow(((GetCellLeft() - m_lBorderWidth) *
                                                m_nLogX)/1440,
               ((GetCellTop() - m_lBorderHeight) * m_nLogY)/1440,
               (GetCellWidth()* m_nLogX)/1440,
               (GetCellHeight()* m_nLogY)/1440, FALSE);
   
            m_edit.ShowWindow(SW_SHOW);
            m_edit.SetFocus();
         }
   
         void CEditGrid::OnUpdateGrid()
         {
            // Check to see if edit is visible.
            BOOL bVisible = ::GetWindowLong(m_edit.GetSafeHwnd(), GWL_STYLE)
                              & WS_VISIBLE;
            if (bVisible)
            {
               CString cStr;
               m_edit.GetWindowText(cStr);
               SetText(cStr);
               m_edit.SetWindowText("");
               m_edit.ShowWindow(SW_HIDE);
            }
         } 




7. Handle the WM_GETDLGCODE and WM_SETFOCUS messages in CEditGrid:

   
      UINT CEditGrid::OnGetDlgCode()
      {
         return DLGC_WANTALLKEYS;
      }
   
      void CEditGrid::OnSetFocus(CWnd* pOldWnd)
      {
         CMSFlexGrid::OnSetFocus(pOldWnd);
   
         OnUpdateGrid();
      } 




8. Create an instance of the CEditGrid control in either of the following ways:
   • Add the MSFlexGrid control to a dialog box or CFormView using the Resource Editor. You can then subclass the control by holding down the CTRL key and double-clicking on the control in the Resource Editor. You must edit the .h file, and change the class from CMSFlexGrid to CEditGrid.
   • Create the control dynamically. To do this, you need to override the CEditGrid::Create functions to call CMSFlexGrid::Create. You also need to call CEditGrid::SubClassWindow() to subclass it. For more information, see the REFERENCES section of this article.



9. Set the following properties for the control:

   
         Cols = 6
         Rows = 20
         FillStyle = 1 - Repeat
         FocusRect = 2 - Heavy 

REFERENCES

For additional information, please see the following articles in the Microsoft Knowledge Base:

Q99161 HOWTO: Derive From Classes not Listed in ClassWizard

Q156051 Messages Not Received by Dynamically Created Control

Q173026 PRB: Message-Handlers For ActiveX Control Aren't Called

© Microsoft Corporation 1998, All Rights Reserved.
Contributions by Kelly Marie Ward, Microsoft Corporation

Keywords          : kbcode kbfile kbole kbsample kbActiveX kbMFC kbVC500 
Version           : WINNT:5.0
Platform          : winnt 
Issue type        : kbhowto 

Last Reviewed: July 14, 1999