Fix : Binding Icon in ToolbarItem in TabbedPage doesn't refresh (#3761)

fixes #3756

Xamarin.Forms.Platform.WPF/Converters/IconConveter.cs

@@ -0,0 +1,46 @@
+using System;
+using System.Globalization;
+using System.IO;
+using System.Windows.Media;
+using Xamarin.Forms.Platform.WPF.Controls;
+using Xamarin.Forms.Platform.WPF.Enums;
+
+namespace Xamarin.Forms.Platform.WPF.Converters
+{
+	public class IconConveter : System.Windows.Data.IValueConverter
+	{
+		public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
+		{
+			if (value is FileImageSource imageSource)
+			{
+				if (Enum.TryParse(imageSource.File, true, out Symbol symbol))
+					return new FormsSymbolIcon() { Symbol = symbol };
+				else if (TryParseGeometry(imageSource.File, out Geometry geometry))
+					return new FormsPathIcon() { Data = geometry };
+				else if (Path.GetExtension(imageSource.File) != null)
+					return new FormsBitmapIcon() { UriSource = new Uri(imageSource.File, UriKind.RelativeOrAbsolute) };
+			}
+
+			return null;
+		}
+
+		public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
+		{
+			throw new NotImplementedException();
+		}
+
+		private bool TryParseGeometry(string value, out Geometry geometry)
+		{
+			geometry = null;
+			try
+			{
+				geometry = Geometry.Parse(value);
+				return true;
+			}
+			catch (Exception)
+			{
+				return false;
+			}
+		}
+	}
+}

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

@@ -1,12 +1,10 @@
 using System;
-using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.ComponentModel;
-using System.IO;
 using System.Windows.Media;
 using System.Windows.Media.Imaging;
 using Xamarin.Forms.Platform.WPF.Controls;
-using Xamarin.Forms.Platform.WPF.Enums;
+using Xamarin.Forms.Platform.WPF.Converters;
 using Xamarin.Forms.Platform.WPF.Extensions;
 
 namespace Xamarin.Forms.Platform.WPF
@@ -52,7 +50,6 @@ protected override void OnElementPropertyChanged(object sender, PropertyChangedE
 				UpdateBackButtonTitle();
 			else if (e.PropertyName == NavigationPage.HasNavigationBarProperty.PropertyName)
 				UpdateNavigationBarVisible();
-
 		}
 
 		void UpdateTitle()
@@ -100,32 +97,22 @@ void UpdateToolbar()
 
 			foreach (var item in Element.ToolbarItems)
 			{
-				FormsAppBarButton appBar = new FormsAppBarButton()
+				var appBar = new FormsAppBarButton() { DataContext = item };
+
+				var iconBinding = new System.Windows.Data.Binding(nameof(item.Icon))
 				{
-					Label = item.Text,
-					Tag = item
+					Converter = new IconConveter()
 				};
 
+				appBar.SetBinding(FormsAppBarButton.IconProperty, iconBinding);
+				appBar.SetBinding(FormsAppBarButton.LabelProperty, nameof(item.Text));
 				appBar.SetValue(FrameworkElementAttached.PriorityProperty, item.Priority);
 
-				if(item.Icon != null)
-				{
-					Symbol symbol;
-					Geometry geometry;
-
-					if (Enum.TryParse(item.Icon.File, true, out symbol))
-						appBar.Icon = new FormsSymbolIcon() { Symbol = symbol };
-					else if (TryParseGeometry(item.Icon.File, out geometry))
-						appBar.Icon = new FormsPathIcon() { Data = geometry };
-					else if (Path.GetExtension(item.Icon.File) != null)
-						appBar.Icon = new FormsBitmapIcon() { UriSource = new Uri(item.Icon.File, UriKind.RelativeOrAbsolute) };
-				}
-
 				appBar.Click += (sender, e) =>
 				{
-					if (appBar.Tag != null && appBar.Tag is ToolbarItem)
+					if (appBar.DataContext is ToolbarItem toolbarItem)
 					{
-						(appBar.Tag as ToolbarItem).Activate();
+						toolbarItem.Activate();
 					}
 				};
 
@@ -153,20 +140,6 @@ private void VisualPageRenderer_CollectionChanged(object sender, System.Collecti
 			UpdateToolbar();
 		}
 
-		private bool TryParseGeometry(string value, out Geometry geometry)
-		{
-			geometry = null;
-			try
-			{
-				geometry = Geometry.Parse(value);
-				return true;
-			}
-			catch(Exception)
-			{
-				return false;
-			}
-		}
-
 		bool _isDisposed;
 
 		protected override void Dispose(bool disposing)

Xamarin.Forms.Platform.WPF/Xamarin.Forms.Platform.WPF.csproj

@@ -87,6 +87,7 @@
     <Compile Include="Converters\CollapseWhenEmptyConverter.cs" />
     <Compile Include="Converters\ColorConverter.cs" />
     <Compile Include="Converters\HeightConverter.cs" />
+    <Compile Include="Converters\IconConveter.cs" />
     <Compile Include="Converters\ImageConverter.cs" />
     <Compile Include="Converters\SymbolToValueConverter.cs" />
     <Compile Include="Converters\ToUpperConverter.cs" />