CreateCompatibleDC用法

      
      

       
       void CBounceWnd::OnTimer(UINT_PTR /* wParam */)
       
       
{
       
       
    if (m_bmBall.m_hObject == NULL)
       
       
        return;     // no bitmap for the ball     CRect rcClient;
       
       
    GetClientRect(rcClient);     CClientDC dc(this);
       
       
    CBitmap* pbmOld = NULL;     CDC dcMem;
       
       
    dcMem.CreateCompatibleDC(&dc);
       
       
    pbmOld = dcMem.SelectObject(&m_bmBall);     dc.BitBlt(m_ptCenter.x - m_sizeTotal.cx / 2,
       
       
            m_ptCenter.y - m_sizeTotal.cy / 2,
       
       
            m_sizeTotal.cx, m_sizeTotal.cy,
       
       
            &dcMem, 0, 0, SRCCOPY);     m_ptCenter += m_sizeMove; 
       
       
    if ((m_ptCenter.x + m_sizeRadius.cx >= rcClient.right) ||
       
       
        (m_ptCenter.x - m_sizeRadius.cx <= 0))
       
       
    {
       
       
        m_sizeMove.cx = -m_sizeMove.cx;
       
       
    }     if ((m_ptCenter.y + m_sizeRadius.cy >= rcClient.bottom) ||
       
       
        (m_ptCenter.y - m_sizeRadius.cy <= 0))
       
       
    {
       
       
        m_sizeMove.cy = -m_sizeMove.cy;
       
       
    }     dcMem.SelectObject(pbmOld);
       
       
    dcMem.DeleteDC();
       
       
}
      
      
      
      

       
       
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