[工程建立]

1. 在ＶＣ用向导生成一个ＱＴ　ＧＵＩ程序，将里面的代码文件等删除（.vcxproj等保留）
2. 在ＶＣ用向导生成另一个ＭＦＣ／Ｒｉｂｂｏｎ程序，将里面的代码资源文件等拷贝到前一工程
3. 进入第一个工程，做必要小修改。

   //[app.cpp]
   QMfcApp* _qApp = nullptr;
   // CQtMFCApplication 构造
   
   CQtMFCApplication::CQtMFCApplication() noexcept
   {
   	m_bHiColorIcons = TRUE;
   
   	int argc = 0;
   	_qApp = new QMfcApp(argc, nullptr);
   	_qApp->mfc_app = this;
   	//...	
   }
   
   int CQtMFCApplication::Run()
   {
   	int ret = _qApp->exec();
   	delete _qApp;
   	ExitInstance(); //needed
   	return ret;
   
   	return CWinAppEx::Run();
   }
   
   
   //[Frame.h]
   class CMainFrame : public CMDIFrameWndEx
   {
   //...
   
   protected:
   	static QWidget* mainWidget;
   	friend QWidget* getMainWidget();
   
   private:
   	void CreateQtWidget();
   };
   
   //[Frame.cpp]
   
   QWidget* CMainFrame::mainWidget = nullptr;
   
   QWidget* getMainWidget()
   {
   	return CMainFrame::mainWidget;
   }
   
   void CMainFrame::CreateQtWidget()
   {
   	AFX_MANAGE_STATE(AfxGetStaticModuleState());
   
   	HWND hWnd = GetSafeHwnd();
   	QWidget* pQWidget = new QWinWidget(hWnd, nullptr);
   	mainWidget = pQWidget;
   }
   
   int CMainFrame::OnCreate(LPCREATESTRUCT lpCreateStruct)
   {
   	//...
   	CreateQtWidget();
   	//...
   }
   
   void CMainFrame::OnDestroy()
   {
   	CMDIFrameWndEx::OnDestroy();
   
   
   	if (mainWidget)
   	{
   		delete mainWidget;
   		mainWidget = nullptr;
   	}
   }
   
   //[view.h]
   class CQtMFCApplicationView : public CView
   {
   	//...
   private:
   	QWidget* m_qtContainer = nullptr;
   	//...
   }
   
   //[view.cpp]
   
   void CQtMFCApplicationView::OnInitialUpdate()
   {
   	CView::OnInitialUpdate();
   
   	m_qtContainer = new QWinWidget(m_hWnd, nullptr);
   	QVBoxLayout* vbox = new QVBoxLayout(m_qtContainer);
   
   	QPushButton* btn = new QPushButton(QString::fromStdWString(L"QPushButton 你好！"), m_qtContainer);
   	btn->setFixedWidth(256);
   	btn->setFixedHeight(64);
   	vbox->addWidget(btn, 0, Qt::AlignCenter);
   
   	m_qtContainer->setLayout(vbox);
   
   	QObject::connect(btn, &QPushButton::clicked, [&]()
   		{
   			QMessageBox::information(getMainWidget(), "QMessageBox Title", QString::fromStdWString(L"你点击了 QPushButton"));
   		});
   }
   
   
   void CQtMFCApplicationView::OnSize(UINT nType, int cx, int cy)
   {
   	CView::OnSize(nType, cx, cy);
   
   	if (m_qtContainer)
   	{
   		CRect clientRect;
   		GetClientRect(&clientRect);
   
   		m_qtContainer->setGeometry(clientRect.left,
   			clientRect.top,
   			clientRect.Width(), clientRect.Height());
   		m_qtContainer->show();
   	}
   }
   
   
   void CQtMFCApplicationView::OnDestroy()
   {
   	CView::OnDestroy();
   
   	if (m_qtContainer)
   	{
   		//!!!必须添加这句，否则delete后，程序崩溃退出
   		//m_qtContainer在创建时，没有PaentWidget. 如果创建时设置，则其不会显示
   		m_qtContainer->setParent(getMainWidget()); 
   		delete m_qtContainer;
   		m_qtContainer = nullptr;
   	}
   	return;
   }