How do I cancel standby and hibernate?

Question

my application running in C#, using third party framework.it works as an UI for many application.my question is when my appplication is running and the system should not happen standby/hybernate OS operations. somehow i have to cancel the event for standby/hybernate raised by OS.please any one help my in this regards.

Thanks Sun

Answer 1

There's no way to cancel the event from within .NET. You'll have to do it with P/Invoke and the Win32 API by handling WM_POWERBROADCAST and returning BROADCAST_QUERY_DENY. Take a look at this CodeGuru page for a push in the right direction.

Also of interest would be this page, detailing some events that are fired in .NET when a user logs off or suspend/hibernates.

Answer 2

This blog post describes how to prevent a PC from going to sleep using SetThreadExecutionState. The code looks like this:

public partial class Window1 : Window
{
    private uint m_previousExecutionState;

    public Window1()
    {
        InitializeComponent();

        // Set new state to prevent system sleep (note: still allows screen saver)
        m_previousExecutionState = NativeMethods.SetThreadExecutionState(
            NativeMethods.ES_CONTINUOUS | NativeMethods.ES_SYSTEM_REQUIRED);
        if (0 == m_previousExecutionState)
        {
            MessageBox.Show("Call to SetThreadExecutionState failed unexpectedly.",
                Title, MessageBoxButton.OK, MessageBoxImage.Error);
            // No way to recover; fail gracefully
            Close();
        }
    }

    protected override void OnClosed(System.EventArgs e)
    {
        base.OnClosed(e);

        // Restore previous state
        if (0 == NativeMethods.SetThreadExecutionState(m_previousExecutionState))
        {
            // No way to recover; already exiting
        }
    }
}

internal static class NativeMethods
{
    // Import SetThreadExecutionState Win32 API and necessary flags
    [DllImport("kernel32.dll")]
    public static extern uint SetThreadExecutionState(uint esFlags);
    public const uint ES_CONTINUOUS = 0x80000000;
    public const uint ES_SYSTEM_REQUIRED = 0x00000001;
}

If you like the application described in the post, there is an updated version here.

Answer 3

Powercfg and shutdown (especially shutdown /a to abort a system shutdown) might prove useful, possibly.