在通用Windows平台中使用SetWaitableTimer

Question

I use SetWaitableTimer from "kernel32.dll" in my UWP app. I want the computer to wake from sleep because of my application. If I run the app in debug mode it works. If I run it in release mode then the computer doesn't wake up.

How can I do to make my application awakened the computer when it is running in realise mode?

private void Button_Click(object sender, RoutedEventArgs e)
    {
        Task.Factory.StartNew(SetWaitForWakeUpTime);
    }

    [DllImport("kernel32.dll")]
    public static extern IntPtr CreateWaitableTimer(IntPtr lpTimerAttributes, bool bManualReset, string lpTimerName);

    [DllImport("kernel32.dll")]
    public static extern bool SetWaitableTimer(IntPtr hTimer, [In] ref long pDueTime, int lPeriod,
                                                IntPtr pfnCompletionRoutine, IntPtr lpArgToCompletionRoutine, bool fResume);

    [DllImport("kernel32.dll", SetLastError = true)]
    public static extern Int32 WaitForSingleObject(IntPtr handle, uint milliseconds);

    static IntPtr handle;

    static void SetWaitForWakeUpTime()
    {
        long duetime = -600000000;

        handle = CreateWaitableTimer(IntPtr.Zero, true, "MyWaitabletimer");
        SetWaitableTimer(handle, ref duetime, 0, IntPtr.Zero, IntPtr.Zero, true);
        uint INFINITE = 0xFFFFFFFF;
        int ret = WaitForSingleObject(handle, INFINITE);
    }

Answer 1

Windows 10 Universal Windows Platform (UWP) apps can use a subset of the Win32 and COM APIs. This subset of APIs was chosen to support key scenarios for Windows Runtime apps that were not already covered by the Windows Runtime, HTML/CSS, or other supported languages or standards. The Windows App Certification Kit ensures that your app uses only this subset of the Win32 and COM API. For the Win32 APIs that can be used in UWP, please see Win32 and COM APIs for UWP apps .

Unfortunately, CreateWaitableTimer and SetWaitableTimer are not in the supported APIs. We can not use them in UWP apps. For a UWP app, it should not be able to wake the system from sleep. But we can prevent the system from sleep by using DisplayRequest class .

Apps that show video or run for extended periods without user input can request that the display remain on by calling DisplayRequest::RequestActive . When a display request is activated, the device's display remains on while the app is visible.

For more info, plesae see Remarks of DisplayRequest class .

But if you are developing apps for enterprise, you can try with Brokered Windows Runtime Components . With this, you have the ability to run existing desktop software assets in one process (desktop component) while interacting with this code in a UWP App. For more info, please check this blog .