Implementing TWAIN Application Loop with MFC

If you are using MFC and C++, the CWinApp::PreTranslateMessage function has to be overridden as follows for DTWAIN to function properly:

// Class declaration for CMyApp

class CMyApp : public CWinApp

{

...

// Definition of overriden PreTranslateMessage( )

BOOL PreTranslateMessage(MSG &msg);

...

};

//------------------------------------------------------------------------------------

// The InitInstance of the application should have the following

BOOL CMyApp::InitInstance( )

{

...

DTWAIN_SysInitialize( );

DTWAIN_SetTwainMode(DTWAIN_MODELESS);

...

}

//----------------------------------------------------------------------------------

// Implementation of overridden PreTranslateMessage( )

BOOL CMyApp::PreTranslateMessage(MSG *msg)

{

// Check if not TWAIN message

if ( !DTWAIN_IsTwainMsg( msg ))

// Do normal processing and return

return CWinApp::PreTranslateMessage(msg);

return TRUE;

}