CDC 逻辑坐标 设备坐标 相互转换

CClientDC dc(this);

    OnPrepareDC(&dc);//转换前记得使用该语句

    CDC* pDC = CDC::FromHandle(pCurve->m_hDC);
    CRect rect;
    rect = pCurve->m_rectTracker.m_rect;
   // pDC->LPtoDP(&rect);
    dc.LPtoDP(&rect);