Re: MessageMap - Funktionszeiger - VS2008

From:
Giovanni Dicanio <giovanniDOTdicanio@REMOVEMEgmail.com>
Newsgroups:
microsoft.public.vc.mfc
Date:
Sat, 11 Jul 2009 12:08:38 +0200
Message-ID:
<#6$1R#gAKHA.4608@TK2MSFTNGP02.phx.gbl>
Giovanni Dicanio ha scritto:

Another approach to implement a custom message map could be to use a map
container (like STL std::map), and associate event IDs to member
functions of C++ classes.

You may want to download a sample MFC project here:

http://www.geocities.com/giovanni.dicanio/vc/TestCustomMessageMap.zip


Moreover, of course it is possible also to put all the event handlers as
member functions implemented in the same message map class (instead of
defining a single class for each event handler).
It all depends on your particular needs and design choices.

Here is the updated sample:

http://www.geocities.com/giovanni.dicanio/vc/TestCustomMessageMap2.zip

and here is the modifications to CMessageMapTest class:

<code>

//-----------------------------------------------------------------------
// Testing custom message map
//-----------------------------------------------------------------------
class CMessageMapTest
{
public:

     // Build the message map, filling the std::map data member
     CMessageMapTest()
     {
         // Add event handlers to the map
         m_events[Event_Click] = CreateHandler(this,
&CMessageMapTest::HandleClick);
         m_events[Event_DoubleClick] = CreateHandler(this,
&CMessageMapTest::HandleDoubleClick);
         m_events[Event_Resize] = CreateHandler(this,
&CMessageMapTest::HandleResize);
     }

     // Cleanup the message map
     virtual ~CMessageMapTest()
     {
         // Delete pointers stored in map
         EventHandlers::iterator it;
         for (it = m_events.begin(); it != m_events.end(); ++it)
         {
             delete it->second;
             it->second = NULL;
         }

         // Clear the map
         m_events.clear();
     }

     // Handle a particular event
     void HandleEvent(Event event, DWORD customData)
     {
         // Call event handler using map
         (*m_events[event])(customData);
     }

private:

     // Event handlers is a map that associates an event ID to an event
handler object
     typedef std::map< Event, IEventHandlerBase * > EventHandlers;

     // Event handlers stored as data members here
     EventHandlers m_events;

     //
     // Some Sample Event Handlers
     //

     void HandleClick(DWORD customData)
     {
         CString msg;
         msg.Format(_T("Handle Click Event (data = %08X)"), customData);
         AfxMessageBox(msg, MB_OK);
     }

     void HandleDoubleClick(DWORD customData)
     {
         CString msg;
         msg.Format(_T("Handle Double-Click Event (data = %08X)"),
customData);
         AfxMessageBox(msg, MB_OK);
     }

     void HandleResize(DWORD customData)
     {
         CString msg;
         msg.Format(_T("Handle Resize Event (data = %08X)"), customData);
         AfxMessageBox(msg, MB_OK);
     }

};

</code>

Giovanni

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