C# Signature:

[DllImport("ntdll.dll", SetLastError=true)]
private static extern uint NtQueryWnfStateData(IntPtr pStateName, IntPtr pTypeId, IntPtr pExplicitScope, out uint nChangeStamp, out IntPtr pBuffer, ref uint nBufferSize);

VB Signature:

Declare Function NtQueryWnfStateData Lib "ntdll.dll" (TODO) As TODO

User-Defined Types:

[StructLayout(LayoutKind.Sequential)]

public struct WNF_TYPE_ID

{

    public Guid TypeId;

}

[StructLayout(LayoutKind.Sequential)]

public struct WNF_STATE_NAME

{

    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 2)]
    public uint[] Data;

    public WNF_STATE_NAME(uint Data1, uint Data2) : this()
    {
    uint[] newData = new uint[2];
    newData[0] = Data1;
    newData[1] = Data2;
    Data = newData;
    }

}

public enum FocusAssistResult

{

    NOT_SUPPORTED = -2,
    FAILED = -1,
    OFF = 0,
    PRIORITY_ONLY = 1,
    ALARMS_ONLY = 2

};

Alternative Managed API:

Do you know one? Please contribute it!

Notes:

This function replaces Quiet Hours in Windows 10 build >= 17083.

Tips & Tricks:

Please add some!

Sample Code:

private FocusAssistResult GetUserNotificationState()

{

    //  Focus Assist:   Windows 10 build >= 17083
    WNF_STATE_NAME WNF_SHEL_QUIETHOURS_ACTIVE_PROFILE_CHANGED = new WNF_STATE_NAME(0xA3BF1C75, 0xD83063E);
    uint nBufferSize = (uint)Marshal.SizeOf(typeof(IntPtr));
    IntPtr pStateName = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(WNF_STATE_NAME)));
    Marshal.StructureToPtr(WNF_SHEL_QUIETHOURS_ACTIVE_PROFILE_CHANGED, pStateName, false);
    bool success = NtQueryWnfStateData(pStateName, IntPtr.Zero, IntPtr.Zero, out uint nChangeStamp, out IntPtr pBuffer, ref nBufferSize) == 0;
    Marshal.FreeHGlobal(pStateName);
    if (success)
    {
    return (FocusAssistResult)pBuffer;
    }

    return FocusAssistResult.FAILED;

}