Use ON_MESSAGE() Macro to Map Less-Common Messages

MS-DOS | WINDOWS             | WINDOWS NT

The information in this article applies to:

• The Microsoft Foundation Classes (MFC) included with:

      - Microsoft C/C++ version 7.0
      - Microsoft Visual C++ for Windows, versions 1.0, 1.5, 1.51, and
        1.52
      - Microsoft Visual C++ 32-bit Edition, version 1.0, 2.0, 2.1, and 4.0
  

SUMMARY

The Microsoft Foundation Class Library includes macros that an application can include in the message map of a CWnd or CWnd derived object.These macros, such as ON_WM_PAINT() and ON_WM_SIZE(), map common messages to default handler functions. The Microsoft Foundation Class Library provides macros for all standard window messages. To process user-defined message or less-common window messages (like WM_COMMNOTIFY), use the ON_MESSAGE() macro. The ON_MESSAGE macro must be used in a CWnd derived class. For example, it cannot be used in a CWinApp class or a CDocument class because neither of these classes is derived from CWnd.

MORE INFORMATION

Here's an example of how an application could use ON_MESSAGE:

  // inside the class declaration
  afx_msg LRESULT OnMyMessage(WPARAM wParam, LPARAM lParam);

  ...

  #define WM_MYMESSAGE (WM_USER + 100)

  BEGIN_MESSAGE_MAP(CMyWnd, CMyParentWndClass)
     ON_MESSAGE(WM_MYMESSAGE, OnMyMessage)
  END_MESSAGE_MAP()

  LRESULT CMyWnd::OnMyMessage(WPARAM WParam, LPARAM LParam)
  {
     return (LRESULT)0;
  }