CEdit重绘垂直居中显示

原文：http://stackoverflow.com/questions/867207/how-can-we-vertically-align-text-in-edit-box

/// 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();
}