fix(xbind): Support nested expression x:Bind events

src/SourceGenerators/Uno.UI.SourceGenerators/Helpers/SymbolExtensions.cs

@@ -144,16 +144,16 @@ public static bool Is(this INamedTypeSymbol symbol, INamedTypeSymbol other)
 				&& symbol.DeclaredAccessibility == Accessibility.Internal
 			);
 
-		public static IEnumerable<IMethodSymbol> GetMethods(this INamedTypeSymbol resolvedType)
+		public static IEnumerable<IMethodSymbol> GetMethods(this ITypeSymbol resolvedType)
 			=> resolvedType.GetMembers().OfType<IMethodSymbol>();
 
-		public static IEnumerable<IMethodSymbol> GetMethodsWithName(this INamedTypeSymbol resolvedType, string name)
+		public static IEnumerable<IMethodSymbol> GetMethodsWithName(this ITypeSymbol resolvedType, string name)
 			=> resolvedType.GetMembers(name).OfType<IMethodSymbol>();
 
-		public static IEnumerable<IFieldSymbol> GetFields(this INamedTypeSymbol resolvedType)
+		public static IEnumerable<IFieldSymbol> GetFields(this ITypeSymbol resolvedType)
 			=> resolvedType.GetMembers().OfType<IFieldSymbol>();
 
-		public static IEnumerable<IFieldSymbol> GetFieldsWithName(this INamedTypeSymbol resolvedType, string name)
+		public static IEnumerable<IFieldSymbol> GetFieldsWithName(this ITypeSymbol resolvedType, string name)
 			=> resolvedType.GetMembers(name).OfType<IFieldSymbol>();
 
 		/// <summary>

src/SourceGenerators/Uno.UI.SourceGenerators/XamlGenerator/NameScope.cs

@@ -20,6 +20,11 @@ public NameScope(string @namespace, string className)
 
 		public List<BackingFieldDefinition> BackingFields { get; } = new List<BackingFieldDefinition>();
 
+		/// <summary>
+		/// List of action handlers for registering x:Bind events
+		/// </summary>
+		public List<BackingFieldDefinition> xBindEventsHandlers { get; } = new List<BackingFieldDefinition>();
+
 		/// <summary>
 		/// Lists the ElementStub builder holder variables used to pin references for implicit pinning platforms
 		/// </summary>

src/SourceGenerators/Uno.UI.SourceGenerators/XamlGenerator/XamlFileGenerator.cs

@@ -674,6 +674,12 @@ private void BuildBackingFields(IIndentedStringBuilder writer)
 				}
 			}
 
+			foreach (var xBindEventHandler in CurrentScope.xBindEventsHandlers)
+			{
+				// Create load-time subjects for ElementName references not in local scope
+				writer.AppendLineInvariant($"{FormatAccessibility(xBindEventHandler.Accessibility)} {GetGlobalizedTypeName(xBindEventHandler.Type)} {xBindEventHandler.Name};");
+			}
+
 			foreach (var remainingReference in CurrentScope.ReferencedElementNames)
 			{
 				// Create load-time subjects for ElementName references not in local scope
@@ -795,16 +801,10 @@ private void BuildCompiledBindingsInitializer(IndentedStringBuilder writer, stri
 						writer.AppendLineInvariant("Bindings.Update();");
 					}
 
-					for (var i = 0; i < CurrentScope.Components.Count; i++)
-					{
-						var component = CurrentScope.Components[i];
-
-						if (HasMarkupExtensionNeedingComponent(component) && IsDependencyObject(component))
-						{
-							writer.AppendLineInvariant($"_component_{i}.UpdateResourceBindings();");
-						}
-					}
+					BuildComponentResouceBindingUpdates(writer);
+					BuildxBindEventHandlerInitializers(writer);
 				}
+
 				writer.AppendLineInvariant(";");
 			}
 		}
@@ -820,21 +820,38 @@ private void BuildCompiledBindingsInitializerForTemplate(IIndentedStringBuilder
 				{
 					using (writer.BlockInvariant($"__fe.Loading += delegate"))
 					{
-						for (var i = 0; i < CurrentScope.Components.Count; i++)
-						{
-							var component = CurrentScope.Components[i];
-
-							if (HasMarkupExtensionNeedingComponent(component) && IsDependencyObject(component))
-							{
-								writer.AppendLineInvariant($"_component_{i}.UpdateResourceBindings();");
-							}
-						}
+						BuildComponentResouceBindingUpdates(writer);
+						BuildxBindEventHandlerInitializers(writer);
 					}
 					writer.AppendLineInvariant(";");
 				}
 			}
 		}
 
+		private void BuildxBindEventHandlerInitializers(IIndentedStringBuilder writer)
+		{
+			foreach (var xBindEventHandler in CurrentScope.xBindEventsHandlers)
+			{
+				writer.AppendLineInvariant($"{xBindEventHandler.Name}?.Invoke();");
+
+				// Only needs to happen once per visual tree creation
+				writer.AppendLineInvariant($"{xBindEventHandler.Name} = null;");
+			}
+		}
+
+		private void BuildComponentResouceBindingUpdates(IIndentedStringBuilder writer)
+		{
+			for (var i = 0; i < CurrentScope.Components.Count; i++)
+			{
+				var component = CurrentScope.Components[i];
+
+				if (HasMarkupExtensionNeedingComponent(component) && IsDependencyObject(component))
+				{
+					writer.AppendLineInvariant($"_component_{i}.UpdateResourceBindings();");
+				}
+			}
+		}
+
 		private void BuildComponentFields(IndentedStringBuilder writer)
 		{
 			for (var i = 0; i < CurrentScope.Components.Count; i++)
@@ -3069,8 +3086,40 @@ void writeEvent(string ownerPrefix)
 						// sanitizing member.Member.Name so that "ViewModel.SearchBreeds" becomes "ViewModel_SearchBreeds"
 						var sanitizedEventTarget = SanitizeResourceName(eventTarget);
 
-						(string target, string weakReference, INamedTypeSymbol sourceType) buildTargetContext()
+						(string target, string weakReference, IMethodSymbol targetMethod) buildTargetContext()
 						{
+							IMethodSymbol FindTargetMethodSymbol(INamedTypeSymbol sourceType)
+							{
+								if (eventTarget.Contains("."))
+								{
+									ITypeSymbol currentType = sourceType;
+
+									var parts = eventTarget.Split('.');
+
+									for (var i = 0; i < parts.Length-1; i++)
+									{
+										var next = currentType.GetAllMembersWithName(parts[i]).FirstOrDefault();
+
+										currentType = next switch
+										{
+											IFieldSymbol fs => fs.Type,
+											IPropertySymbol ps => ps.Type,
+											null => throw new InvalidOperationException($"Unable to find member {parts[i]} on type {currentType}"),
+											_ => throw new InvalidOperationException($"The field {next.Name} is not supported for x:Bind event binding")
+										};
+									}
+
+									var method = currentType.GetMethods().FirstOrDefault(m => m.Name == parts.Last())
+										?? throw new InvalidOperationException($"Failed to find {parts.Last()} on {currentType}");
+
+									return method;
+								}
+								else
+								{
+									return sourceType.GetMethods().FirstOrDefault(m => m.Name == eventTarget);
+								}
+							}
+
 							if (isInsideDataTemplate.isInside)
 							{
 								var dataTypeObject = FindMember(isInsideDataTemplate.xamlObject, "DataType", XamlConstants.XamlXmlNamespace)
@@ -3083,32 +3132,44 @@ void writeEvent(string ownerPrefix)
 									// Use of __rootInstance is required to get the top-level DataContext, as it may be changed
 									// in the current visual tree by the user.
 									$"(__rootInstance as global::Uno.UI.DataBinding.IWeakReferenceProvider).WeakReference",
-									dataTypeSymbol
+									FindTargetMethodSymbol(dataTypeSymbol)
 								);
 							}
 							else
 							{
+
 								return (
 									$"{member.Member.Name}_{sanitizedEventTarget}_That.Target as {_className.className}",
 									$"({eventSource} as global::Uno.UI.DataBinding.IWeakReferenceProvider).WeakReference",
-									FindType(_className.className)
+									FindTargetMethodSymbol(FindType(_className.className))
 								);
 							}
 						}
 
 						var targetContext = buildTargetContext();
 
-						var targetMethodHasParamters = targetContext.sourceType.GetMethods().FirstOrDefault(m => m.Name == eventTarget)?.Parameters.Any() ?? false;
+						var targetMethodHasParamters = targetContext.targetMethod?.Parameters.Any() ?? false;
 						var xBindParams = targetMethodHasParamters ? parms : "";
 
-						//
-						// Generate a weak delegate, so the owner is not being held onto by the delegate. We can
-						// use the WeakReferenceProvider to get a self reference to avoid adding the cost of the
-						// creation of a WeakReference.
-						//
-						writer.AppendLineInvariant($"var {member.Member.Name}_{sanitizedEventTarget}_That = {targetContext.weakReference};");
+						var builderName = $"_{ownerPrefix}_{CurrentScope.xBindEventsHandlers.Count}_{member.Member.Name}_{sanitizedEventTarget}_Builder";
+
+						CurrentScope.xBindEventsHandlers.Add(
+							new BackingFieldDefinition("global::System.Action", builderName, Accessibility.Private)
+						);
+
+						using (writer.BlockInvariant($"{builderName} = () => "))
+						{
+							//
+							// Generate a weak delegate, so the owner is not being held onto by the delegate. We can
+							// use the WeakReferenceProvider to get a self reference to avoid adding the cost of the
+							// creation of a WeakReference.
+							//
+							writer.AppendLineInvariant($"var {member.Member.Name}_{sanitizedEventTarget}_That = {targetContext.weakReference};");
+
+							writer.AppendLineInvariant($"/* first level targetMethod:{targetContext.targetMethod} */ {closureName}.{member.Member.Name} += ({parms}) => ({targetContext.target})?.{eventTarget}({xBindParams});");
+						}
 
-						writer.AppendLineInvariant($"{closureName}.{member.Member.Name} += ({parms}) => ({targetContext.target})?.{eventTarget}({xBindParams});");
+						writer.AppendLineInvariant($";");
 					}
 					else
 					{
@@ -3123,7 +3184,7 @@ void writeEvent(string ownerPrefix)
 						//
 						writer.AppendLineInvariant($"var {member.Member.Name}_{sanitizedMemberValue}_That = ({eventSource} as global::Uno.UI.DataBinding.IWeakReferenceProvider).WeakReference;");
 
-						writer.AppendLineInvariant($"{closureName}.{member.Member.Name} += ({parms}) => ({member.Member.Name}_{sanitizedMemberValue}_That.Target as {_className.className})?.{member.Value}({parms});");
+						writer.AppendLineInvariant($"/* second level */ {closureName}.{member.Member.Name} += ({parms}) => ({member.Member.Name}_{sanitizedMemberValue}_That.Target as {_className.className})?.{member.Value}({parms});");
 					}
 				}
 				else

src/Uno.UI.Tests/Windows_UI_Xaml_Data/xBindTests/Controls/Binding_Event_Nested.xaml

@@ -0,0 +1,15 @@
+<Page x:Class="Uno.UI.Tests.Windows_UI_Xaml_Data.xBindTests.Controls.Binding_Event_Nested"
+	  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+	  xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+	  xmlns:local="using:Uno.UI.Tests.Windows_UI_Xaml_Data.xBindTests.Controls"
+	  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+	  xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+	  mc:Ignorable="d">
+
+	<Grid>
+		<CheckBox x:Name="myCheckBox"
+				  x:FieldModifier="public"
+				  Checked="{x:Bind ViewModel.OnCheckedRaised}"
+				  Unchecked="{x:Bind ViewModel.OnUncheckedRaised}"/>
+	</Grid>
+</Page>

src/Uno.UI.Tests/Windows_UI_Xaml_Data/xBindTests/Controls/Binding_Event_Nested.xaml.cs

@@ -0,0 +1,49 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.IO;
+using System.Linq;
+using System.Runtime.InteropServices.WindowsRuntime;
+using Windows.Foundation;
+using Windows.Foundation.Collections;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Controls.Primitives;
+using Windows.UI.Xaml.Data;
+using Windows.UI.Xaml.Input;
+using Windows.UI.Xaml.Media;
+using Windows.UI.Xaml.Navigation;
+
+// The Blank Page item template is documented at https://go.microsoft.com/fwlink/?LinkId=234238
+
+namespace Uno.UI.Tests.Windows_UI_Xaml_Data.xBindTests.Controls
+{
+	/// <summary>
+	/// An empty page that can be used on its own or navigated to within a Frame.
+	/// </summary>
+	public sealed partial class Binding_Event_Nested : Page
+	{
+		public Binding_Event_Nested()
+		{
+			this.InitializeComponent();
+		}
+
+		public Binding_Event_Nested_ViewModel ViewModel { get; } = new Binding_Event_Nested_ViewModel();
+	}
+
+	public class Binding_Event_Nested_ViewModel
+	{
+		public int CheckedRaised { get; private set; }
+		public int UncheckedRaised { get; private set; }
+
+		public void OnCheckedRaised()
+		{
+			CheckedRaised++;
+		}
+
+		public void OnUncheckedRaised(object sender, RoutedEventArgs args)
+		{
+			UncheckedRaised++;
+		}
+	}
+}

src/Uno.UI.Tests/Windows_UI_Xaml_Data/xBindTests/Controls/Binding_Event_Nested_DataTemplate.xaml

@@ -0,0 +1,22 @@
+<Page x:Class="Uno.UI.Tests.Windows_UI_Xaml_Data.xBindTests.Controls.Binding_Event_Nested_DataTemplate"
+	  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+	  xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+	  xmlns:local="using:Uno.UI.Tests.Windows_UI_Xaml_Data.xBindTests.Controls"
+	  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+	  xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+	  mc:Ignorable="d">
+
+	<ContentControl x:Name="root"
+					x:FieldModifier="public">
+		<ContentControl.ContentTemplate>
+			<DataTemplate x:DataType="local:Binding_Event_Nested_DataTemplate_Model">
+				<Grid>
+					<CheckBox x:Name="myCheckBox"
+						  x:FieldModifier="public"
+						  Checked="{x:Bind ViewModel.OnCheckedRaised}"
+						  Unchecked="{x:Bind ViewModel.OnUncheckedRaised}"/>
+				</Grid>
+			</DataTemplate>
+		</ContentControl.ContentTemplate>
+	</ContentControl>
+</Page>

src/Uno.UI.Tests/Windows_UI_Xaml_Data/xBindTests/Controls/Binding_Event_Nested_DataTemplate.xaml.cs

@@ -0,0 +1,52 @@
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.IO;
+using System.Linq;
+using System.Runtime.InteropServices.WindowsRuntime;
+using Windows.Foundation;
+using Windows.Foundation.Collections;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Controls.Primitives;
+using Windows.UI.Xaml.Data;
+using Windows.UI.Xaml.Input;
+using Windows.UI.Xaml.Media;
+using Windows.UI.Xaml.Navigation;
+
+// The Blank Page item template is documented at https://go.microsoft.com/fwlink/?LinkId=234238
+
+namespace Uno.UI.Tests.Windows_UI_Xaml_Data.xBindTests.Controls
+{
+	/// <summary>
+	/// An empty page that can be used on its own or navigated to within a Frame.
+	/// </summary>
+	public sealed partial class Binding_Event_Nested_DataTemplate : Page
+	{
+		public Binding_Event_Nested_DataTemplate()
+		{
+			this.InitializeComponent();
+		}
+	}
+
+	public class Binding_Event_Nested_DataTemplate_Model
+	{
+		public Binding_Event_Nested_DataTemplate_ViewModel ViewModel { get; } = new Binding_Event_Nested_DataTemplate_ViewModel();
+	}
+
+	public class Binding_Event_Nested_DataTemplate_ViewModel
+	{
+		public int CheckedRaised { get; private set; }
+		public int UncheckedRaised { get; private set; }
+
+		internal void OnCheckedRaised()
+		{
+			CheckedRaised++;
+		}
+
+		internal void OnUncheckedRaised(object sender, RoutedEventArgs args)
+		{
+			UncheckedRaised++;
+		}
+	}
+}