MFC 畫壹個透明矩形

簡單實例如下：

//CBrush br;

//CPen pen;

pen.CreatePen(PS_SOLID,1,RGB(255,0,0));

br.CreateStockObject(NULL_BRUSH);

dc.SelectObject(&pen);

dc.SelectObject(&br);

//dc.Rectangle(1,1,100,100);