Applying an Update UI Notification Interface to User-defined Controls

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• Download demo executable - 4 KB

Introduction

I often run into a situation where I want to apply a UI update notification to a user-defined control in the way as it is provided by the MFC for menu items, tool bar buttons and status bar controls. In this case, a self-defined message handler is used to properly respond to an UPDATE_COMMAND_UI

Please note: There are two ways you have to prepare your source code for properly applying update UI notifications to user-defined controls. It depends on the type of window class your controls are located in; once for a dialog class derived from CDialogCFormViewCFormViewhere. But first, let's take a look at the implementation details.

Implementation Details to Perform with a CDialog Instance

1. Include the MFC header file declaring private Windows messages and macros in the source file (.cpp) of your dialog class implementation.

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   #include <afxpriv.h>

2. In the corresponding header file where your dialog window class is defined, declare the prototypes of the WM_KICKIDLEWM_KICKIDLE

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   //{{AFX_MSG(CCmdUIDemoDlg)
   virtual BOOL OnInitDialog();
   afx_msg void OnPaint();
   [...]
   //}}AFX_MSG
   afx_msg void OnKickIdle();
   afx_msg void OnUpdateUserButton(CCmdUI* pCmdUI);
   DECLARE_MESSAGE_MAP()

3. Update your message map in .cpp file to map the WM_KICKIDLE

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   BEGIN_MESSAGE_MAP(CCmdUIDemoDlg, CDialog)
   	//{{AFX_MSG_MAP(CCmdUIDemoDlg)
   	ON_WM_PAINT()
   	[...]
   	//}}AFX_MSG_MAP
   	ON_MESSAGE_VOID(WM_KICKIDLE, OnKickIdle)
   	ON_UPDATE_COMMAND_UI(IDC_BUTTON1, OnUpdateUserButton)
   END_MESSAGE_MAP()

4. At last, implement the bodies of both message handlers:

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   void CCmdUIDemoDlg::OnKickIdle()
   {
   	UpdateDialogControls(this, FALSE);
   }
   
   void CCmdUIDemoDlg::OnUpdateUserButton(CCmdUI *pCmdUI)
   {
   	pCmdUI->Enable(m_bToggle);
   }

5. Done! By the pCmdUICCmdUIEnable()

Implementation Details to Perform With a CFormView Instance (Not Part of the Demo Code)

To use the update notification mechanism for a CFormView CDialog instance, perform the following steps by analogy:

1. Include the MFC header file declaring private Windows messages and macros in the source file (.cpp) of your dialog class implementation.

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   #include <afxpriv.h>

2. In the corresponding header file where your view class is defined, declare the prototypes of the WM_IDLEUPDATECMDUIWM_IDLEUPDATECMDUI

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   //{{AFX_MSG(CMyFormView)
   [...]
   //}}AFX_MSG
   afx_msg void OnIdleUpdateCmdUI();
   afx_msg void OnUpdateUserControl(CCmdUI* pCmdUI);
   DECLARE_MESSAGE_MAP()

3. Update your message map in .cpp file to map the WM_IDLEUPDATECMDUI

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   BEGIN_MESSAGE_MAP(CMyFormView, CFormView)
   	//{{AFX_MSG_MAP(CMyFormView)
   	[...]
   	//}}AFX_MSG_MAP
   	ON_MESSAGE_VOID(WM_IDLEUPDATECMDUI, OnIdleUpdateCmdUI)
   	ON_UPDATE_COMMAND_UI(IDC_MY_CONTROL, OnUpdateUserControl)
   END_MESSAGE_MAP()

4. At last, implement the bodies of both message handlers:

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   void CMyFormView::OnIdleUpdateCmdUI()
   {
   	UpdateDialogControls(this, FALSE);
   }
   
   void CMyFormView::OnUpdateUserControl(CCmdUI *pCmdUI)
   {
   	pCmdUI->Enable(...);
   }

5. Done!

History

• 31^st July, 2000: Initial version

License

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