问题
How can I determine if my displays are in "Clone Mode" without using either COPP (Computer Output Protection Protocol) or OPM (Output Protection Protocol) on Windows?
Vista solution:
hMonitor = MonitorFromWindow (HWND_DESKTOP, MONITOR_DEFAULTTOPRIMARY);
bSuccess = GetNumberOfPhysicalMonitorsFromHMONITOR (hMonitor, &dwMonitorCount);
回答1:
I assume you've already tried EnumDisplayMonitors() and it didn't work. So if that returns a single HMONITOR for each set of cloned displays, you could compare this set of results to the result of EnumDisplayDevices(). Devices returned by EnumDisplayDevices() that are attached to the desktop but aren't returned by EnumDisplayMonitors() should be clones.
来源：https://stackoverflow.com/questions/80103/detect-clone-mode-display-setup