MFC窗口创建机制

class CMyWinApp : public CWinApp
{
public:
    CMyWinApp();
    virtual BOOL InitInstance();
    virtual BOOL InitApplication();
    virtual int Run();
    virtual BOOL OnIdle(LONG ICount);
    virtual int ExitInstance();
};

int CMyWinApp::ExitInstance()
{
    AfxMessageBox("善后处理");
    return CWinApp::ExitInstance();
}
BOOL CMyWinApp::OnIdle(LONG ICount)
{
    //AfxMessageBox("空闲处理");//死循环
    return CWinApp::OnIdle(ICount);
}
int CMyWinApp::Run()
{
    CWinApp::Run();
    AfxMessageBox("消息循环");
    return 0;
}
BOOL CMyWinApp::InitApplication()
{
    AfxMessageBox("初始化");
    return CWinApp::InitApplication();
}

BOOL CMyWinApp::InitInstance()
{//此函数中的this为&theApp
    CMyFrameWnd* pFrame = new CMyFrameWnd;
    pFrame->Create(NULL, "测试");
    this->m_pMainWnd = pFrame;
    //pFrame->ShowWindow(SW_SHOW);//相当于下面的语句
    ::ShowWindow(pFrame->m_hWnd, SW_SHOW);
    //pFrame->UpdateWindow();相当于下面的语句
    ::UpdateWindow(pFrame->m_hWnd);
    return TRUE;
}

class CMyFrameWnd : public CFrameWnd
{
public:
    virtual LRESULT WindowProc(UINT message, WPARAM wParam, LPARAM lParam); //声明虚函数
};
//实现虚函数
LRESULT CMyFrameWnd::WindowProc(
    UINT message, WPARAM wParam, LPARAM lParam)
{//此函数的this为pFrame
    switch (message) {
    case WM_CREATE:
        AfxMessageBox("WM_CREATE消息被处理");
        break;
    case WM_PAINT:
    {
        PAINTSTRUCT ps = { 0 };
        HDC hdc = ::BeginPaint(this->m_hWnd, &ps);
        ::TextOut(hdc, 100, 100, "hello", 5);
        ::EndPaint(this->m_hWnd, &ps);
    }
   
    }
    return CFrameWnd::WindowProc(message, wParam, lParam);
}

class CMyFrameWnd : public CFrameWnd
{
public:
    virtual LRESULT WindowProc(UINT message, WPARAM wParam, LPARAM lParam);
    int m_x;
    int m_y;
};
case WM_MOUSEMOVE:
    {
        m_x = LOWORD(lParam);//wParam传递的是否按左键右键ctrl等键
        m_y = HIWORD(lParam);
        ::InvalidateRect(this->m_hWnd, NULL, TRUE);//重画
    }