Fix compiler warnings in WPF platform project (#6616)

Xamarin.Forms.Platform.WPF/Deserializer.cs

@@ -15,22 +15,22 @@ namespace Xamarin.Forms.Platform.WPF
 	{
 		const string PropertyStoreFile = "PropertyStore.forms";
 
-		public async Task<IDictionary<string, object>> DeserializePropertiesAsync()
+		public Task<IDictionary<string, object>> DeserializePropertiesAsync()
 		{
 			IsolatedStorageFile isoStore = IsolatedStorageFile.GetStore(IsolatedStorageScope.User | IsolatedStorageScope.Assembly, null, null);
 
 			if (!isoStore.FileExists(PropertyStoreFile))
-				return new Dictionary<string, object>(4);
+				return Task.FromResult<IDictionary<string, object>>(new Dictionary<string, object>(4));
 			
 			using (IsolatedStorageFileStream stream = new IsolatedStorageFileStream(PropertyStoreFile, FileMode.Open, isoStore))
 			{
 				if (stream.Length == 0)
-					return new Dictionary<string, object>(4);
+					return Task.FromResult<IDictionary<string, object>>(new Dictionary<string, object>(4));
 
 				try
 				{
 					var serializer = new DataContractSerializer(typeof(IDictionary<string, object>));
-					return (IDictionary<string, object>)serializer.ReadObject(stream);
+					return Task.FromResult((IDictionary<string, object>)serializer.ReadObject(stream));
 				}
 				catch (Exception e)
 				{
@@ -38,7 +38,7 @@ namespace Xamarin.Forms.Platform.WPF
 					Log.Warning("Xamarin.Forms PropertyStore", $"Exception while reading Application properties: {e}");
 				}
 
-				return null;
+				return Task.FromResult<IDictionary<string, object>>(null);
 			}
 		}
 

Xamarin.Forms.Platform.WPF/Renderers/ImageRenderer.cs

@@ -145,7 +145,7 @@ namespace Xamarin.Forms.Platform.WPF
 
 	public sealed class UriImageSourceHandler : IImageSourceHandler
 	{
-		public async Task<System.Windows.Media.ImageSource> LoadImageAsync(ImageSource imagesoure, CancellationToken cancelationToken = new CancellationToken())
+		public Task<System.Windows.Media.ImageSource> LoadImageAsync(ImageSource imagesoure, CancellationToken cancelationToken = new CancellationToken())
 		{
 			BitmapImage bitmapimage = null;
 			var imageLoader = imagesoure as UriImageSource;
@@ -156,7 +156,7 @@ namespace Xamarin.Forms.Platform.WPF
 				bitmapimage.UriSource = imageLoader.Uri;
 				bitmapimage.EndInit();
 			}
-			return bitmapimage;
+			return Task.FromResult<System.Windows.Media.ImageSource>(bitmapimage);
 		}
 	}
 }

Xamarin.Forms.Platform.WPF/Renderers/ListViewRenderer.cs

@@ -63,7 +63,7 @@ namespace Xamarin.Forms.Platform.WPF
 				UpdateVerticalScrollBarVisibility();
 
 				if (Element.SelectedItem != null)
-					OnElementItemSelected(null, new SelectedItemChangedEventArgs(Element.SelectedItem));
+					OnElementItemSelected(null, new SelectedItemChangedEventArgs(Element.SelectedItem, -1));
 			}
 
 			base.OnElementChanged(e);

Xamarin.Forms.Platform.WPF/VisualElementTracker.cs

@@ -30,7 +30,9 @@ namespace Xamarin.Forms.Platform.WPF
 
 		bool _invalidateArrangeNeeded;
 		bool _isPanning;
+#pragma warning disable 0414 // The private field 'field' is assigned but its value is never used
 		bool _isPinching;
+#pragma warning restore 0414
 
 		bool _touchFrameReportedEventSet;
 		int _touchPoints = 1;

Xamarin.Forms.Platform.WPF/WPFDeviceInfo.cs

@@ -11,7 +11,9 @@ namespace Xamarin.Forms.Platform.WPF
 	internal class WPFDeviceInfo : DeviceInfo
 	{
 		internal const string BWPorientationChangedName = "Xamarin.WPF.OrientationChanged";
+#pragma warning disable 0649 // Field 'field' is never assigned to, and will always have its default value 'value'
 		readonly double _scalingFactor;
+#pragma warning restore 0649
 
 		public WPFDeviceInfo()
 		{