03.2.1 mfc中的winmain函数(3).txt

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InitInstance函数
再回到例3-7所示的AfxWinMain函数，可以看到在接下来的代码中，pThread和pApp调用了三个函数（加灰显示的代码行），这三个函数就完成了Win32程序所需要的几个步骤：设计窗口类、注册窗口类、创建窗口、显示窗口、更新窗口、消息循环，以及窗口过程函数。pApp首先调用InitApplication函数，该函数完成MFC内部管理方面的工作。接着，调用pThread的InitInstance函数。在Test程序中，可以发现从CWinApp派生的应用程序类CTestApp也有一个InitInstance函数，其声明代码如下所示。

virtual BOOL InitInstance();

从其定义可以知道，InitInstance函数是一个虚函数。根据类的多态性原理，可以知道AfxWinMain函数这里实际上调用的是子类CTestApp的InitInstance函数（读者可以在此函数处设置一个断点，并调试运行程序以验证一下）。CTestApp类的InitInstance函数定义代码如例3-9所示。

例3-9

BOOL CTestApp::InitInstance()

{

    AfxEnableControlContainer();

 

    // Standard initialization

    // If you are not using these features and wish to reduce the size

    //  of your final executable, you should remove from the following

    //  the specific initialization routines you do not need.

 

#ifdef _AFXDLL

    Enable3dControls();         // Call this when using MFC in a shared DLL

#else

    Enable3dControlsStatic();   // Call this when linking to MFC statically

#endif

 

    // Change the registry key under which our settings are stored.

    // TODO: You should modify this string to be something appropriate

    // such as the name of your company or organization.

    SetRegistryKey(_T("Local AppWizard-Generated Applications"));

 

    LoadStdProfileSettings();  // Load standard INI file options (including MRU)

 

    // Register the application's document templates.  Document templates

    //  serve as the connection between documents, frame windows and views.

 

    CSingleDocTemplate* pDocTemplate;

①  pDocTemplate = new CSingleDocTemplate(

        IDR_MAINFRAME,

        RUNTIME_CLASS(CTestDoc),

        RUNTIME_CLASS(CMainFrame),       // main SDI frame window

        RUNTIME_CLASS(CTestView));

    AddDocTemplate(pDocTemplate);

 

    // Parse command line for standard shell commands, DDE, file open

    CCommandLineInfo cmdInfo;

    ParseCommandLine(cmdInfo);

 

    // Dispatch commands specified on the command line

    if (!ProcessShellCommand(cmdInfo))

        return FALSE;

 

    // The one and only window has been initialized, so show and update it.

    m_pMainWnd->ShowWindow(SW_SHOW);

    m_pMainWnd->UpdateWindow();

 

    return TRUE;

}