VC++编程常见问题解答十一


问：如何限制mdi子框架最大化时的大小?

答：用ptMaxTrackSize代替prMaxSize,如下所示:
void CChildFrame::OnGetMinMaxInfo(MINMAXINFO FAR* lpMMI)
{
   // TODO: Add your message handler code here and/or call default
   CChildFrame::OnGetMinMaxInfo(lpMMI);
   lpMMI->ptMaxTrackSize.x = 300;
   lpMMI->ptMaxTrackSize.y = 400;
}


问：如何切换视口而不破坏它们?


我创建了一个带有静态分隔区的sdi应用程序,左边显示工作区,右过显示左边选取
的东西.我想达到的是如果在分隔区之间进行切换,而不覆盖或破坏原来的CView对
象.答：以下代码是你所想要的:


class CExSplitterWnd : public CSplitterWnd
{
// Construction
public:
    CExSplitterWnd();
// Overrides
    // ClassWizard generated virtual function overrides
    //{{AFX_VIRTUAL(CExSplitterWnd)
    //}}AFX_VIRTUAL
// Implementation
    virtual ~CExSplitterWnd();
    BOOL AttachView(CWnd* pView, int row, int col);
    BOOL DetachView(int row, int col);
    // Generated message map functions
    //{{AFX_MSG(CExSplitterWnd)
        // NOTE - the ClassWizard will add and remove member functions here.
    //}}AFX_MSG
    DECLARE_MESSAGE_MAP()
};

CExSplitterWnd::CExSplitterWnd()
{
}

CExSplitterWnd::~CExSplitterWnd()
{
}

BOOL CExSplitterWnd::AttachView(CWnd* pView, int row, int col)
{
    //Make sure the splitter window was created
    if (!IsWindow(m_hWnd))
    {
        ASSERT(0);
        TRACE(_T("Create the splitter window before attaching windows to panes"));
        return (FALSE);
    }

    //Make sure the row and col indices are within bounds
    if (row >= GetRowCount() || col >= GetColumnCount())
    {
        ASSERT(0);
        return FALSE;
    }

    //Is the window to be attached a valid one
    if (pView == NULL || (!IsWindow(pView->m_hWnd)))
    {
        ASSERT(0);
        return FALSE;
    }

    pView->SetDlgCtrlID(IdFromRowCol(row, col));
    pView->SetParent(this);
    pView->ShowWindow(SW_SHOW);
    pView->UpdateWindow();
    return (TRUE);
}

BOOL CExSplitterWnd::DetachView(int row, int col)
{
    //Make sure the splitter window was created
    if (!IsWindow(m_hWnd))
    {
        ASSERT(0);
        TRACE(_T("Create the splitter window before attaching windows to panes"));
        return (FALSE);
    }

    //Make sure the row and col indices are
    //within bounds
    if (row >= GetRowCount() || col >= GetColumnCount())
    {
        ASSERT(0);
        return FALSE;
    }

    CWnd* pWnd = GetPane(row, col);
    if (pWnd == NULL || (!IsWindow(pWnd->m_hWnd)))
    {
        ASSERT(0);
        return FALSE;
    }

    pWnd->ShowWindow(SW_HIDE);
    pWnd->UpdateWindow();

    //Set the parent window handle to NULL so that this child window is not
    //destroyed when the parent (splitter) is destroyed
    pWnd->SetParent(NULL);
    return (TRUE);
}

问：改变列表控制时发生闪烁现象?


我创建了一个简单的对话框,在对话框中设置了一个列表控件,这个控件占用了对
话框的全部 客户区.对话框是可以改变大小的,因此我要保证列表控件在对话框中
维持正确的位置,在对话 框的ONSize()事件中我对列表控件使用了MoveWindow(),
这起到了作用,但当用户改变对话框 的大小时,列表控件不停地闪烁.
答：要解决这个问题,在用MoveWindow之前,先用ShowWindow(SW_HIDE)隐藏列表控
件,然后在MoveWindow之后用ShowWindow(SW_SHOW)来显示列表控件.

问：处理列表控件可见项的问题?


我在一个列表控件中加入了好多条目.我通过获取某个条目是否可见或最后是哪个
条目来进行 处理.我看了CListCtrl::GetItem()的帮助,但是没有找到如何判断一
个条目是否可见的方法.
答：如果你只想处理可见的条目,你可以用GetTopIndex.它返回最大可见条目的索
引值,然后 你再用GetCountPerPage来得到在可见区域的条目数.

问：产生线程的问题?


我在使用CreateThread时碰到了问题.我想让调用的函数和被调用的函数属于同一
个类,结果 在我调用CreateThread时得到如下错误:
error C2440: 'type cast' : cannot convert from 'unsigned long (__stdcall Cdmi::*)(void *)' to 'unsigned long (__stdcall *)(void *)'
A1:(1)'unsigned long (__stdcall Cdmi::*)(void *)'是指向Cdmi某个成员函数的指针.
(2)'unsigned long (__stdcall *)(void *)'仅仅只是一个c形式函数的指针.
编译器无法将(1)转换为(2)是因为c++成员函数取第一个(隐藏)参数"this 
pointer" 作为成员函数,但当是一个静态的成员时则例外.可按如下方法解决.


class XMyThread
{
public:
    void StartThread(void);
    virtual UINT ThreadFunction(void);
    static UINT __bogusthreadfunc(LPVOID lpparam);
};

void XMyThread::StartThread()
{
    AfxBeginThread(__bogusthreadfunc,this);
}

UINT XMyThread::ThreadFunction(void)
{
    //here you do all your real work
    return 0;
}

UINT XMyThread::__bogusthreadfunc(LPVOID lpparam)
{
     XMyThread* This = dynamic_cast
(lpparam);
     return This->ThreadFunction();
}

for the sake of clairty, I did not add StopThread and I did not save the
CWinThread* returned by AfxBeginThread.

If you wanted a thread that does other things, simply derive from XMyThread
and override ThreadFunction()

example:
class XAnotherThread : public XMyThread
{
    virtual UINT ThreadFunction(void);
};

UINT XAnotherThread :: ThreadFunction(void)
{
    //do some other work here
    return 0;
}

A2:Cdmi::MonitorFiles()是个静态的成员函数.