Introduction - If you have any usage issues, please Google them yourself
CDC*pMemDC = new CDC()
pMemDC->CreateCompatibleDC(pScreenDC)
//然后创建位图:
CBitmap*pBitmap = new CBitmap()
pBitmap->CreateCompatibleBitmap(pScreenDC, pRect->Width(), pRect->Height()) # pRect为用户选取的范围
CBitmap*pOldBitmap = pMemDC->SelectObject(pBitmap)
//之后就可以把指定区域的内容复制到位图中。