捕获Windows 10（WPF）中的屏幕锁定事件

Question

Tell me what to do, I don't know where to look for the answer.

I have a WPF application that works with the tablet's camera using AForge. When the user locks the system by keyboard shortcut "Win+L" - the camera is no longer in use (indicator is off), because I'm in control of this process through the event is given below.

 private void SystemEvents_SessionSwitch(object sender, SessionSwitchEventArgs e)
    {
        switch (e.Reason)
        {

            case SessionSwitchReason.SessionLock: StopCam(); break;
            case SessionSwitchReason.SessionUnlock:
                if (this.Window.WindowState != WindowState.Minimized)
                {
                    StartCam();
                }
                break;
        }
    }

If the user push the button of lock of the screen (usually on top of the tablet), my camera does not turn off (indicator lit). How do I track this event?

ps my WPF application will run on Windows 10 tablets.

Answer 1

Maybe i have a solution. This code works on PC but i didn't tested it on tablet (because i don't have one). You need to add using System.Windows.Interop;

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    protected override void OnSourceInitialized(EventArgs e)
    {
        base.OnSourceInitialized(e);
        HwndSource source = PresentationSource.FromVisual(this) as HwndSource;
        source.AddHook(WndProc);
    }

    private const int WM_SYSCOMMAND = 0x0112;
    private const int SC_MONITORPOWER = 0xf170;

    private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
    {
        if (msg == WM_SYSCOMMAND)
        {
            if (wParam.ToInt32() == SC_MONITORPOWER)
            {
                switch (lParam.ToInt32())
                {
                    case -1:
                        this.listBox1.Items.Add("display is powering on");
                        break;

                    case 2:
                        this.listBox1.Items.Add("display is being shut off");
                        break;
                }
            }
        }

        return IntPtr.Zero;
    }

}