如何检测屏幕方向

Question

I am trying differenciate between the device being in Landscape or Portrait mode. 180° rotations don't matter to me, just which side is longer.

I have tried

SimpleOrientation OReading = SimpleOrientationSensor.GetDefault().GetCurrentOrientation();

if(OReading == SimpleOrientation.NotRotated || OReading == SimpleOrientation.Rotated180DegreesCounterclockwise)
    ApplicationData.Current.LocalSettings.Values["Orientation"] = "Landscape";
if (OReading == SimpleOrientation.Rotated90DegreesCounterclockwise || OReading == SimpleOrientation.Rotated270DegreesCounterclockwise)
    ApplicationData.Current.LocalSettings.Values["Orientation"] = "Portrait";

but the first line already throws a NullReferenceException. What would be the correct way to do this?

I have a .NET component that could technically also perform this, but I would prefer to do it in UWP if possible.

Note that I am not running in a simulator, but launching the App on a device that supports rotation.

I actually don't need the sensor data though, I just want to know how the screen orientation is, which can be different from the sensor data.

Edit:

public async void ChangedAsync(AppResourceGroupInfoWatcher sender, AppResourceGroupInfoWatcherExecutionStateChangedEventArgs args)
{
    DisplayInformation current = DisplayInformation.GetForCurrentView();

This also does not work, and in UWP it gives me the crash

Windows.Graphics.Display: GetForCurrentView must be called on a thread that is associated with a CoreWindow.

The function is getting called by an AppResourceGroupInfoWatcher.

I am using:

using System;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using System.Threading.Tasks;
using Windows.ApplicationModel;
using Windows.Foundation;
using Windows.Foundation.Metadata;
using Windows.Graphics.Display;
using Windows.Storage;
using Windows.System;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;

targeting version 1803

Answer 1

This should work.

bool isInLandscapeMode = 
Windows.UI.ViewManagement.ApplicationView.GetForCurrentView().Orientation == 
Windows.UI.ViewManagement.ApplicationViewOrientation.Landscape;

ApplicationData.Current.LocalSettings.Values["Orientation"] = isInLandscapeMode ? 
"Landscape" : "Portrait";