ON_MESSAGE 

Indicates which function will handle a user-defined message.


ON_MESSAGE(message, memberFxn )

Parameters

message

The message ID.

memberFxn

The name of the message-handler function to which the message is mapped.

The type of the function must be afx_msg LRESULT (CWnd::*)(WPARAM, LPARAM).

User-defined messages are usually defined in the range WM_USER to 0x7FFF. User-defined messages are any messages that are not standard Windows WM_MESSAGE messages. There should be exactly one ON_MESSAGE macro statement in your message map for every user-defined message that must be mapped to a message-handler function.

NoteNote

In addition to user-defined messages, ON_MESSAGE handles less common Windows messages. For more information, see the Knowledge Base article Q99848.

For more information and examples, see Message Handling and Mapping Topics and User-Defined Handlers

// example for ON_MESSAGE
#define WM_MYMESSAGE (WM_USER + 1)
BEGIN_MESSAGE_MAP( CMyWnd, CMyParentWndClass )
    ON_MESSAGE( WM_MYMESSAGE, OnMyMessage )
    // ... Possibly more entries to handle additional messages
END_MESSAGE_MAP( )
// implementation for WM_MYMESSAGE handler
LRESULT CMyWnd::OnMyMessage( WPARAM wParam, LPARAM lParam ) 
{
   // ... Handle message here
   return 0L;
}

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