继承的CEdit控件(用于垂直居中的文本)行为异常

我在这个问题的第一个答案中使用了代码: How can we vertically align text in edit box? 将CEdit控件中的文本垂直居中。

这是使用过的类 CEditVC

/// HEADER //////////////////////////////////////////

class CEditVC : public CEdit
{
public:
    CEditVC();

protected:
    CRect m_rectNCBottom;
    CRect m_rectNCTop;

public:
    virtual ~CEditVC();

protected:
    afx_msg void OnNcCalcSize(BOOL bCalcValidRects, NCCALCSIZE_PARAMS FAR* lpncsp);
    afx_msg void OnNcPaint();
    afx_msg UINT OnGetDlgCode();

    DECLARE_MESSAGE_MAP()
};

/// IMPLEMENTATION /////////////////////////////////////////

CEditVC::CEditVC()
    : m_rectNCBottom(0, 0, 0, 0)
    , m_rectNCTop(0, 0, 0, 0)
{
}

CEditVC::~CEditVC()
{
}

BEGIN_MESSAGE_MAP(CEditVC, CEdit)
    ON_WM_NCCALCSIZE()
    ON_WM_NCPAINT()
    ON_WM_GETDLGCODE()
END_MESSAGE_MAP()

void CEditVC::OnNcCalcSize(BOOL bCalcValidRects, NCCALCSIZE_PARAMS FAR* lpncsp) 
{
    CRect rectWnd, rectClient;

    //calculate client area height needed for a font
    CFont *pFont = GetFont();
    CRect rectText;
    rectText.SetRectEmpty();

    CDC *pDC = GetDC();

    CFont *pOld = pDC->SelectObject(pFont);
    pDC->DrawText("Ky", rectText, DT_CALCRECT | DT_LEFT);
    UINT uiVClientHeight = rectText.Height();

    pDC->SelectObject(pOld);
    ReleaseDC(pDC);

    //calculate NC area to center text.

    GetClientRect(rectClient);
    GetWindowRect(rectWnd);

    ClientToScreen(rectClient);

    UINT uiCenterOffset = (rectClient.Height() - uiVClientHeight) / 2;
    UINT uiCY = (rectWnd.Height() - rectClient.Height()) / 2;
    UINT uiCX = (rectWnd.Width() - rectClient.Width()) / 2;

    rectWnd.OffsetRect(-rectWnd.left, -rectWnd.top);
    m_rectNCTop = rectWnd;

    m_rectNCTop.DeflateRect(uiCX, uiCY, uiCX, uiCenterOffset + uiVClientHeight + uiCY);

    m_rectNCBottom = rectWnd;

    m_rectNCBottom.DeflateRect(uiCX, uiCenterOffset + uiVClientHeight + uiCY, uiCX, uiCY);

    lpncsp->rgrc[0].top +=uiCenterOffset;
    lpncsp->rgrc[0].bottom -= uiCenterOffset;

    lpncsp->rgrc[0].left +=uiCX;
    lpncsp->rgrc[0].right -= uiCY;

}

void CEditVC::OnNcPaint() 
{
    Default();

    CWindowDC dc(this);
    CBrush Brush(GetSysColor(COLOR_WINDOW));

    dc.FillRect(m_rectNCBottom, &Brush);
    dc.FillRect(m_rectNCTop, &Brush);
}

UINT CEditVC::OnGetDlgCode() 
{
    if(m_rectNCTop.IsRectEmpty())
    {
        SetWindowPos(NULL, 0, 0, 0, 0, SWP_NOOWNERZORDER | SWP_NOSIZE | SWP_NOMOVE | SWP_FRAMECHANGED);
    }

    return CEdit::OnGetDlgCode();
}

我创建了新的CEdit继承控件,如下所示:

// Header File
CEditVC *mp_inputUser;

// Source File
OnInitDialog()
{
mp_inputUser = new CEditVC();
mp_inputUser->Create(WS_VISIBLE | WS_CHILD, CRect(10,10,100,100), this, 1);
}

但是控件没有显示光标,如果我键入一个字符,它会将自己分割成两部分,并且动作非常奇怪。

什么可能导致这种情况?是否有更晚的(更好的)版本?