Qt based Application Extension

This examples shows how to use the  and  classes to implement a Qt based user interface in a plugin DLL.

The plugin implements and exports a C function showDialog that can be called by any Windows application to display a modal Qt dialog. Before a Qt based user interface can be created a  object must exist, and the calling application's event loop and the Qt event loop must run together.

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         BOOL WINAPI DllMain( HINSTANCE hInstance, DWORD dwReason, LPVOID /*lpvReserved*/ ) {     static bool ownApplication = FALSE;     if ( dwReason == DLL_PROCESS_ATTACH )         ownApplication = QMfcApp::pluginInstance( hInstance );     if ( dwReason == DLL_PROCESS_DETACH && ownApplication )         delete qApp;     return TRUE; }
       
      
     
    

The DLL entry point function DllMain uses the QMfcApp::pluginInstance function to make sure that exactly one instance of exists in the process, and that the DLL owning that instance stays loaded in memory.

extern "C" __declspec(dllexport) bool showDialog( HWND parent ) {     QWinWidget win( parent );     win.showCentered();     QMessageBox::about( &win, "About QtMfc", "QtMfc Version 1.0\nCopyright (C) 2003" );     return TRUE; }

The C function showDialog is exported from the DLL and uses the  class to provide proper stacking and modality between the native Win32 window and the .

 http://doc.qt.digia.com/solutions/4/qtwinmigrate/winmigrate-qt-dll-example.html

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