Lumia 950 and 950 XL screen size detection on WP8.1 Silverlight

ScreenSizeHelper.cs

using System;
using System.Diagnostics;
using System.Linq;
using System.Windows;
using Microsoft.Phone.Info;

namespace PhoneApp1
{
	public class ScreenSizeHelper
	{
		public static double GetScaleFactor()
		{
			// Lumia 950 and 950 XL always returns wrong ScaleFactor 160
			return IsWqhdDevice() ? 320 : Application.Current.Host.Content.ScaleFactor;
		}

		public static Size GetPhysicalScreenResolution()
		{
			// Lumia 950 and 950 XL always returns wrong Size 768x1280
			if (IsWqhdDevice()) return new Size(1440, 2560);

			try
			{
				Size size = (Size)DeviceExtendedProperties.GetValue("PhysicalScreenResolution");
				return size;
			}
			catch (Exception e)
			{
				Debug.WriteLine("Error getting PhysicalScreenResolution {0}", e);
				return new Size(480, 800);
			}
		}

		// all device codes for Lumia 950 and Lumia 950 XL
		private static readonly string[] wqhdDevices = { "rm-1104", "rm-1105", "rm-1118", "rm-1085", "rm-1116" };
		private static bool? isWqhdDevice;

		public static bool IsWqhdDevice()
		{
			if (!isWqhdDevice.HasValue)
			{
				string deviceName = DeviceStatus.DeviceName.ToLower();
				isWqhdDevice = wqhdDevices.Any(d => deviceName.Contains(d));
			}
			return isWqhdDevice.Value;
		}
	}
}