检测显示器数量

Question

I already tried Screen.AllScreen, SystemInformation.MonitorCount, and WMI but all of them failed.

My application runs as a windows service, hence no visual Form or UI. Both Screen.AllScreen and SystemInformation.MonitorCount returns 1 even when I have 2 monitors. If I run my application in console, it returns the correct count of display but my requirement is that my application to run as a windows service (no UI).

Thanks!

Answer 1

Found answer to my own question. Still end up using WMI.

I was initially using Win32_DesktopMonitor giving a non-reliable answer.

Using this query:

"SELECT * FROM Win32_PnPEntity WHERE Service = 'monitor'"

WMI returns the correct monitor instance connected to my PC.

Answer 2

I went with Win32_PnPEntity because it represents the information for Plug and Play Devices in your Device Manager, which will show you when you have a monitors plugged in. The way the query works in "searcher" is more likely to be accurate than others since it uses the Like Operator. I do this because on 3 different computers the monitor entries in Device manager appeared differently. Eg (Pnp-Monitor, Pnp Monitor (Standard), Generic Pnp Monitor).

private int CountMonitorsInstalled()
{
    try
    {
     ManagementObjectSearcher searcher = new ManagementObjectSearcher("root\\CIMV2", "select * from Win32_PnPEntity WHERE Name LIKE '%PnP%Monitor%'");
     return searcher.Get().Count;
    }
    catch(Exception ex)
    {
      return 0;
    }

}