UlteriusServer.Api.Win32.Display.SetPrimary C# (CSharp) Method

        public static string SetPrimary(string deviceName)
        {
            var id = int.Parse(Regex.Match(deviceName, @"\d+").Value) - 1;
            var originalMode = new Devmode();
            originalMode.dmSize = (short) Marshal.SizeOf(originalMode);
            EnumDisplaySettings(deviceName, ENUM_CURRENT_SETTINGS, ref originalMode);
            var offsetx = originalMode.dmPositionX;
            var offsety = originalMode.dmPositionY;
            originalMode.dmPositionX = 0;
            originalMode.dmPositionY = 0;

            ChangeDisplaySettingsEx(deviceName, ref originalMode, (IntPtr) null,
                ChangeDisplaySettingsFlags.CDS_SET_PRIMARY | ChangeDisplaySettingsFlags.CDS_UPDATEREGISTRY |
                ChangeDisplaySettingsFlags.CDS_NORESET, IntPtr.Zero);
            var device = new DisplayDevice();
            device.cb = Marshal.SizeOf(device);

            // Update remaining devices
            for (uint otherid = 0; EnumDisplayDevices(null, otherid, ref device, 0); otherid++)
            {
                if (device.StateFlags.HasFlag(DisplayDeviceStateFlags.AttachedToDesktop) && otherid != id)
                {
                    device.cb = Marshal.SizeOf(device);
                    var otherDeviceMode = new Devmode();

                    EnumDisplaySettings(device.DeviceName, -1, ref otherDeviceMode);

                    otherDeviceMode.dmPositionX -= offsetx;
                    otherDeviceMode.dmPositionY -= offsety;

                    ChangeDisplaySettingsEx(
                        device.DeviceName,
                        ref otherDeviceMode,
                        (IntPtr) null,
                        ChangeDisplaySettingsFlags.CDS_UPDATEREGISTRY | ChangeDisplaySettingsFlags.CDS_NORESET,
                        IntPtr.Zero);
                }

                device.cb = Marshal.SizeOf(device);
            }

            // Apply settings
            return
                GetMessageForCode(ChangeDisplaySettingsEx(null, IntPtr.Zero, (IntPtr) null,
                    ChangeDisplaySettingsFlags.CDS_NONE, (IntPtr) null));
        }