fix: Adjust generation for x:Bind events in x:Load context

Author: jeromelaban

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

@@ -802,7 +802,6 @@ private void BuildCompiledBindingsInitializer(IndentedStringBuilder writer, stri
 					}
 
 					BuildComponentResouceBindingUpdates(writer);
-					BuildxBindEventHandlerInitializers(writer);
 				}
 
 				writer.AppendLineInvariant(";");
@@ -828,14 +827,14 @@ private void BuildCompiledBindingsInitializerForTemplate(IIndentedStringBuilder
 			}
 		}
 
-		private void BuildxBindEventHandlerInitializers(IIndentedStringBuilder writer)
+		private void BuildxBindEventHandlerInitializers(IIndentedStringBuilder writer, string prefix = "")
 		{
 			foreach (var xBindEventHandler in CurrentScope.xBindEventsHandlers)
 			{
-				writer.AppendLineInvariant($"{xBindEventHandler.Name}?.Invoke();");
+				writer.AppendLineInvariant($"{prefix}{xBindEventHandler.Name}?.Invoke();");
 
 				// Only needs to happen once per visual tree creation
-				writer.AppendLineInvariant($"{xBindEventHandler.Name} = null;");
+				writer.AppendLineInvariant($"{prefix}{xBindEventHandler.Name} = null;");
 			}
 		}
 
@@ -913,6 +912,8 @@ private void BuildCompiledBindings(IndentedStringBuilder writer, string classNam
 
 								writer.AppendLineInvariant($"owner._component_{i}{wrapInstance}.ApplyXBind();");
 							}
+
+							BuildxBindEventHandlerInitializers(writer, "owner.");
 						}
 					}
 					using (writer.BlockInvariant($"void {bindingsInterfaceName}.StopTracking()")) { }

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

@@ -15,6 +15,10 @@
 						  x:FieldModifier="public"
 						  Checked="{x:Bind ViewModel.OnCheckedRaised}"
 						  Unchecked="{x:Bind ViewModel.OnUncheckedRaised}"/>
+					<CheckBox x:Name="myCheckBox2"
+						  x:FieldModifier="public"
+						  Checked="{x:Bind ViewModel.OnCheckedRaised}"
+						  Unchecked="{x:Bind ViewModel.OnUncheckedRaised}"/>
 				</Grid>
 			</DataTemplate>
 		</ContentControl.ContentTemplate>

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

@@ -0,0 +1,17 @@
+<Page x:Class="Uno.UI.Tests.Windows_UI_Xaml_Data.xBindTests.Controls.Binding_xLoad_Event"
+	  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 x:Name="rootGrid"
+		  x:FieldModifier="public"
+		  x:Load="{x:Bind TopLevelVisiblity, Mode=OneWay}">
+		<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_xLoad_Event.xaml.cs

@@ -0,0 +1,53 @@
+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_xLoad_Event : Page
+	{
+		public Binding_xLoad_Event()
+		{
+			this.InitializeComponent();
+		}
+
+		public bool TopLevelVisiblity
+		{
+			get { return (bool)GetValue(TopLevelVisiblityProperty); }
+			set { SetValue(TopLevelVisiblityProperty, value); }
+		}
+
+		// Using a DependencyProperty as the backing store for TopLevelVisiblity.  This enables animation, styling, binding, etc...
+		public static readonly DependencyProperty TopLevelVisiblityProperty =
+			DependencyProperty.Register("TopLevelVisiblity", typeof(bool), typeof(Binding_xLoad_Event), new PropertyMetadata(false));
+
+		public Binding_xLoad_Event_ViewModel ViewModel { get; } = new Binding_xLoad_Event_ViewModel();
+	}
+
+	public class Binding_xLoad_Event_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/Given_xBind_Binding.cs

@@ -741,6 +741,21 @@ public void When_Event_Nested_DataTemplate()
 
 			Assert.AreEqual(1, dc.ViewModel.CheckedRaised);
 			Assert.AreEqual(1, dc.ViewModel.UncheckedRaised);
+
+			var checkBox2 = SUT.FindName("myCheckBox2") as CheckBox;
+
+			Assert.AreEqual(1, dc.ViewModel.CheckedRaised);
+			Assert.AreEqual(1, dc.ViewModel.UncheckedRaised);
+
+			checkBox2.IsChecked = true;
+
+			Assert.AreEqual(2, dc.ViewModel.CheckedRaised);
+			Assert.AreEqual(1, dc.ViewModel.UncheckedRaised);
+
+			checkBox2.IsChecked = false;
+
+			Assert.AreEqual(2, dc.ViewModel.CheckedRaised);
+			Assert.AreEqual(2, dc.ViewModel.UncheckedRaised);
 		}
 
 		[TestMethod]
@@ -803,6 +818,62 @@ public void When_xLoad_DataTemplate()
 			Assert.AreEqual(Visibility.Collapsed, topLevelContent.Visibility);
 		}
 
+		[TestMethod]
+		public void When_xLoad_Event()
+		{
+			var SUT = new Binding_xLoad_Event();
+
+			SUT.ForceLoaded();
+
+			Assert.IsNull(SUT.myCheckBox);
+			Assert.IsNull(SUT.rootGrid);
+
+			SUT.TopLevelVisiblity = true;
+
+			Assert.IsNotNull(SUT.myCheckBox);
+			Assert.IsNotNull(SUT.rootGrid);
+
+			var checkBox = SUT.FindName("myCheckBox") as CheckBox;
+
+			Assert.AreEqual(0, SUT.ViewModel.CheckedRaised);
+			Assert.AreEqual(0, SUT.ViewModel.UncheckedRaised);
+
+			checkBox.IsChecked = true;
+
+			Assert.AreEqual(1, SUT.ViewModel.CheckedRaised);
+			Assert.AreEqual(0, SUT.ViewModel.UncheckedRaised);
+
+			checkBox.IsChecked = false;
+
+			Assert.AreEqual(1, SUT.ViewModel.CheckedRaised);
+			Assert.AreEqual(1, SUT.ViewModel.UncheckedRaised);
+
+			SUT.TopLevelVisiblity = false;
+
+			// After reload
+			SUT.TopLevelVisiblity = true;
+
+			Assert.IsNotNull(SUT.myCheckBox);
+			Assert.IsNotNull(SUT.rootGrid);
+
+			var checkBox2 = SUT.FindName("myCheckBox") as CheckBox;
+
+			Assert.AreNotEqual(checkBox, checkBox2);
+
+			Assert.AreEqual(1, SUT.ViewModel.CheckedRaised);
+			Assert.AreEqual(1, SUT.ViewModel.UncheckedRaised);
+
+			checkBox2.IsChecked = true;
+
+			Assert.AreEqual(2, SUT.ViewModel.CheckedRaised);
+			Assert.AreEqual(1, SUT.ViewModel.UncheckedRaised);
+
+			checkBox2.IsChecked = false;
+
+			Assert.AreEqual(2, SUT.ViewModel.CheckedRaised);
+			Assert.AreEqual(2, SUT.ViewModel.UncheckedRaised);
+		}
+
 		[TestMethod]
 		public void When_PropertyChanged_Empty()
 		{