Time left until Windows suspend - c++

Question

Is there a way to query windows how much time is left until it goes to suspend/sleep mode?
I am using vbscript and suspect there might be a WMI answer, but any language like c/c++, *.NET, or even java, if possible, may fit my needs.
EDIT
I want to be able to query Windows with a method, not to be alerted by events when it is about to suspend.

Answer 1

There's no API to know how much time is left since Windows will try to complete entering S3 (Sleep) or S4 (Hibernate) as quick as possible.
Windows will send a notification to all processes about the pending power state change and allow applications to prepare for that event.
You can find most of what you need here.
Basically you have 20 seconds to process the first message. Your process can delay replying to the message, taking care of all the various power cycle tasks, e.g. close files, save your state, etc.

Answer 2

You might want to call CallNtPowerInformation API function that takes the following params:
NTSTATUS WINAPI CallNtPowerInformation(
_In_ POWER_INFORMATION_LEVEL InformationLevel,
_In_ PVOID lpInputBuffer,
_In_ ULONG nInputBufferSize,
_Out_ PVOID lpOutputBuffer,
_In_ ULONG nOutputBufferSize
);
In the InformationLevel paramer you pass the SystemPowerInformation enum value that fills the lpOutputBuffer with a SYSTEM_POWER_INFORMATION structure:
typedef struct _SYSTEM_POWER_INFORMATION {
ULONG MaxIdlenessAllowed;
ULONG Idleness;
ULONG TimeRemaining;
UCHAR CoolingMode;
} SYSTEM_POWER_INFORMATION, *PSYSTEM_POWER_INFORMATION;
Then get the TimeRemaining, which is expressed in seconds.
edit: tested in VB.NET.
edit: code added.
Queryer.vb
Imports System.Runtime.InteropServices
Public Class Queryer
Const SystemPowerInformation As Integer = 12
Const STATUS_SUCCESS As Integer = 0
Private Structure SYSTEM_POWER_INFORMATION
Public MaxIdlenessAllowed As UInteger
Public Idleness As UInteger
Public TimeRemaining As Integer
Public CoolingMode As Byte
End Structure
<DllImport("PowrProf.dll", SetLastError:=True, CharSet:=CharSet.Auto)>
Public Shared Function CallNtPowerInformation(
ByVal InformationLevel As Int32,
ByVal lpInputBuffer As IntPtr,
ByVal nInputBufferSize As UInt32,
ByVal lpOutputBuffer As IntPtr,
ByRef nOutputBufferSize As UInt32) As UInt32
End Function
Public Function Query() As Integer
Dim PowerInformation As SYSTEM_POWER_INFORMATION
Dim Status As IntPtr = IntPtr.Zero
Dim ReturnValue As UInteger
Try
Status = Marshal.AllocCoTaskMem(Marshal.SizeOf(GetType(SYSTEM_POWER_INFORMATION)))
ReturnValue = CallNtPowerInformation(SystemPowerInformation, Nothing, 0, Status, Marshal.SizeOf(GetType(SYSTEM_POWER_INFORMATION)))
PowerInformation = Marshal.PtrToStructure(Status, GetType(SYSTEM_POWER_INFORMATION))
Catch ex As Exception
Return 0
Finally
Marshal.FreeCoTaskMem(Status)
End Try
Return PowerInformation.TimeRemaining
End Function
End Class
Form:
Public Class Form1
Public Sub Loader() Handles Me.Load
Dim rolex As New Timer()
rolex.Interval = 500
AddHandler rolex.Tick, AddressOf TimerScattato
rolex.Start()
End Sub
Private Sub TimerScattato()
Dim secondi As Integer = q.Query()
Dim iSpan As TimeSpan = TimeSpan.FromSeconds(secondi)
lblTimeLeft.Text = String.Format("{0,2}:{1,2}:{2,2}", iSpan.Hours, iSpan.Minutes, iSpan.Seconds)
End Sub
Private q As New Queryer
End Class