ExcludeClipRect区域裁剪问题

CPaintDC dc(this);
CRect rt1;
CPen newPen;
newPen.CreatePen(PS_SOLID,1,RGB(0,0,0));
CPen *pOldPen = dc.SelectObject(&newPen);
CBrush* pOldBrush = (CBrush*)dc.SelectStockObject(NULL_BRUSH);
GetDlgItem(IDC_BUTTON_QUERY)->GetWindowRect(&rt1);
dc.ExcludeClipRect(rt1);
dc.RoundRect(rt,CPoint(10,10));
dc.SelectObject(pOldPen);
dc.SelectObject(pOldBrush);

绘制时使用ExcludeClipRect裁剪出一块区域，则此区域不会受此次绘制影响，保持绘制前状态；