Passing Media Load Pattern Callbacks

The media load pattern callback routine you wrote previously is passed in at runtime. The callbacks are registered when your application joins the session. When your tool agrees to handle a request, a callback message is sent. A callback message is also sent if a file is joined or if a message is failed.

// Join the session and register patterns and callbacks 
sessPats = ttdt_session_join( 0, 0, session_shell, this, 1 );  

// Accept responsibility to handle a request
    _contractPats = ttdt_message_accept(msg, CoEditor::_contractCB_, shell, this, 1, 1 ); 

 // Optional task: Join a file (Can be called recursively)
    if (_filePats == 0) {_filePats = ttdt_file_join( _file, TT_SCOPE_NONE, 1,
                     CoEditor::_fileCB_, this );
    }  

// Fail a message 
tttk_message_fail( msg, TT_DESKTOP_ENODATA, 0, 1 );