The CClientDC class is derived from CDC and takes care of calling the Windows functionsGetDC at construction time andReleaseDC at destruction time. This means that the device context associated with a CClientDC object is the client area of a window. 其实就多了一个窗口句柄类成员变量
其实就多了一个窗口句柄类成员变量
而DC则包含该窗口的所有区域。