UWP: Detect app gaining/losing focus

Question

I want to be able to prevent the screen saver from triggering while my app is in use by using the DisplayRequest class, but I only want to do this while it\'s the active app

Answer 1

We can use CoreWindow.Activated event to detect when a UWP app is activated or deactivated. This method is fired when the window completes activation or deactivation. And for a UWP app, we usually only have one window. So we can add some code like following in Application.OnLaunched method to detect:

Window.Current.CoreWindow.Activated += (sender, args) =>
{
    if (args.WindowActivationState == Windows.UI.Core.CoreWindowActivationState.Deactivated)
    {
        System.Diagnostics.Debug.WriteLine("Deactivated " + DateTime.Now);
    }
    else
    {
        System.Diagnostics.Debug.WriteLine("Activated " + DateTime.Now);
    }
};

Besides this, you can also use CoreApplication.GetCurrentView method or CoreWindow.GetForCurrentThread method to get the CoreWindow.