Q104637: HOWTO: Trap Arrow Keys in an Edit Control of a Dialog Box

Article: Q104637
Product(s): Microsoft C Compiler
Version(s): winnt:1.0,2.0,2.1,4.0
Operating System(s): 
Keyword(s): kbCtrl kbMFC KbUIDesign kbVC kbGrpDSMFCATL
Last Modified: 07-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 1.0, 1.5, 1.51, 1.52 
   - Microsoft Visual C++, 32-bit Editions, versions 1.0, 2.0, 2.1, 4.0 
-------------------------------------------------------------------------------

SUMMARY
=======

This article describes how to trap arrow keys in an edit control of a dialog box
with the Microsoft Foundation Classes (MFC) versions 2.0 and above. Although the
example in this article uses an edit control, a similar mechanism applies to
other controls as well.

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

To trap the arrow keys in an edit control of a dialog box, the following steps
may be taken:

1. Create a dialog box class derived from CDialog. For example, you can create a
  dialog box class called CMyDlg:public CDialog with Class Wizard.

2. Create your own edit class and trap WM_GETDLGCODE and WM_KEYDOWN. The code
  will resemble the following:

        class CMyEdit : public CEdit
        {
        // Construction
        public:
             CMyEdit();

        public:
             virtual ~CMyEdit();
        protected:
             afx_msg UINT OnGetDlgCode();
             afx_msg void OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags);
             DECLARE_MESSAGE_MAP()
        };

        CMyEdit::CMyEdit()
        {
        }

        CMyEdit::~CMyEdit()
        {
        }

        BEGIN_MESSAGE_MAP(CMyEdit, CEdit)
             ON_WM_GETDLGCODE()
             ON_WM_KEYDOWN()
        END_MESSAGE_MAP()

        UINT CMyEdit::OnGetDlgCode()
        {

             return DLGC_WANTARROWS|DLGC_WANTALLKEYS|DLGC_WANTCHARS;
        }

        void CMyEdit::OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
       {
             //Check if the key pressed was a DOWN ARROW key
             if (nChar == VK_DOWN)
                  AfxMessageBox("It is a down arrow key!");
             if (nChar == VK_RIGHT)
                  AfxMessageBox("It is a right arrow key!");
             if (nChar == VK_LEFT)
                  AfxMessageBox("It is a left arrow key!");
             if (nChar == VK_UP)
                  AfxMessageBox("It is a up arrow key!");
             CEdit::OnKeyDown(nChar, nRepCnt, nFlags);
        }

  NOTE: if Class Wizard is used to add a CMyEdit class, you must derive the
  class from CWnd first and then manually change any references of CWnd to
  CEdit in the code. It is important to trap WM_GEDLGCODE in your own edit
  class and specify DLGC_WANTARROWS in OnGetDlgCode().

3. Create a member variable that maps to your own edit class in the dialog box
  class and override CWnd::DoDataExchange(). Your code should resemble the
  following:

        class CMyDlg : public CDialog
        {
        public:
             CMyEdit m_edit;
        protected:
             virtual void DoDataExchange(CDataExchange* pDX); //DDX/DDV

             DECLARE_MESSAGE_MAP()
        };
        void CMyDlg::DoDataExchange(CDataExchange* pDX)
        {
             CDialog::DoDataExchange(pDX);
             DDX_Control(pDX, IDC_EDIT1, m_edit);
        }

  NOTE: This can be done easily by Class Wizard. For example, you can add a
  member variable m_edit and map it to CEdit and then manually change CEdit
  references in MyEdit.CPP and MyEdit.H files to CMyEdit.

Additional query words: kbinf 1.00 1.50 1.51 1.52 2.00 2.10 2.50 2.51 3.00 3.10 4.00

======================================================================
Keywords          : kbCtrl kbMFC KbUIDesign kbVC kbGrpDSMFCATL 
Technology        : kbAudDeveloper kbMFC
Version           : winnt:1.0,2.0,2.1,4.0
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.