vc畫圖的一些簡單方法演示，各種DC



/*HDC hdc = ::GetDC(this->GetSafeHwnd());
 MoveToEx(hdc,m_BtnDown.x,m_BtnDown.y,NULL);
 LineTo(hdc,point.x,point.y);
 ::ReleaseDC(this->GetSafeHwnd(),hdc);*/

 /*CDC *pDC=GetDC();
 pDC->MoveTo(m_BtnDown.x,m_BtnDown.y);
 pDC->LineTo(point.x,point.y);
 ReleaseDC(pDC);*/

 /*CClientDC dc(this);
 dc.MoveTo(m_BtnDown);
 dc.LineTo(point);
 CView::OnLButtonUp(nFlags, point);*/

 /*CWindowDC dc(GetDesktopWindow());
 dc.MoveTo(m_BtnDown);
 dc.LineTo(point);*/

 CClientDC dc(this);
 /*獲得空畫刷*/
 CBrush *bsh = CBrush::FromHandle((HBRUSH)GetStockObject(NULL_BRUSH));
 CBrush *oldbs = dc.SelectObject(bsh);
 dc.Rectangle(CRect(m_BtnDown,point));
 dc.SelectObject(oldbs);