方法一：
CRect rt;
int screenW;
int screenH;
CWnd* pDeskTop = this->GetDesktopWindow();
pDeskTop->GetClientRect(rt);
screenW = rt.Width();
screenH = rt.Height();
方法二：
int x = GetSystemMetrics(SM_CXFULLSCREEN);
int y = GetSystemMetrics(SM_CYFULLSCREEN);