How to detect duplicated monitors as separate screens

Question

Using the answer in this question I can get the \"screen\" count. However, this doesn\'t seem to work with monitors that are set to \"duplicate\" (one monitor is reported in

Answer 1

James Barrass' answer didn't work for me. I ended up going with the answer here: link

Here's the code:

public static int GetScreenCount()
{
    ManagementObjectSearcher searcher =
        new ManagementObjectSearcher("root\\CIMV2",
        "SELECT * FROM Win32_PnPEntity where service =\"monitor\"");

    return searcher.Get().Count;
}

Answer 2

See This question and use the provided (and fixed in the answer) wrapper for QueryDisplayConfig.

change the signature of the import to have out DisplayConfigTopologyId topology as the last parameter.

Use the QueryDisplayFlags.DatabaseCurrent for the display flags, otherwise you'll get status 87 (invalid parameter)

After calling QueryDisplayFlags the topology will be Clone, Extend etc.

call the method...

var status = CCDWrapper.QueryDisplayConfig(
    CCDWrapper.QueryDisplayFlags.DatabaseCurrent,
    ref numPathArrayElements, pathInfoArray, ref numModeInfoArrayElements,
    modeInfoArray, out currentTopologyId);

In my tests numPathArrayElements always came back as the number of monitors currently In Use. If I changed it to "Show Only Screen 1", It said 1 screen, topology internal. "Show Only Screen 2" came back with 1 screen external. "Cloned" showed 2 screens.