feat(xLoad): Add xLoad binding capabilities

doc/articles/features/windows-ui-xaml-xbind.md

@@ -86,3 +86,9 @@ Uno supports the [`x:Bind`](https://docs.microsoft.com/en-us/windows/uwp/xaml-pl
   ```xaml
   <TextBox FontFamily="{x:Bind (FontFamily)MyComboBox.SelectedValue}" />
   ```
+
+- `x:Load` binding
+  ```xaml
+  <TextBox x:Load="{x:Bind IsMyControlVisible}" />
+  ```
+  See the [WinUI documentation](https://docs.microsoft.com/en-us/windows/uwp/xaml-platform/x-load-attribute) for more details.

doc/articles/supported-features.md

@@ -65,7 +65,7 @@
 ### Runtime Performance
 
 - CoreDispatcher Priority support (Large UIs performance)
-- `x:DeferLoadStrategy="Lazy"` and `x:Load="false"` support (responsive design performance)
+- `x:DeferLoadStrategy="Lazy"`, `x:Load="false"` and `x:Load="{x:Bind ...}" support (responsive design performance)
 - Image explicit size support (performance)
 - Event tracing (sub-millisecond [ETL performance profiling](Assets/diagnostics.PNG))
 - Internal logging

src/SamplesApp/UITests.Shared/UITests.Shared.projitems

@@ -833,6 +833,22 @@
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>
     </Page>
+    <Page Include="$(MSBuildThisFileDirectory)Windows_UI_Xaml\xLoadTests\xLoad_FindName.xaml">
+      <SubType>Designer</SubType>
+      <Generator>MSBuild:Compile</Generator>
+    </Page>
+    <Page Include="$(MSBuildThisFileDirectory)Windows_UI_Xaml\xLoadTests\xLoad_Literal.xaml">
+      <SubType>Designer</SubType>
+      <Generator>MSBuild:Compile</Generator>
+    </Page>
+    <Page Include="$(MSBuildThisFileDirectory)Windows_UI_Xaml\xLoadTests\xLoad_Test_For_Leak.xaml">
+      <SubType>Designer</SubType>
+      <Generator>MSBuild:Compile</Generator>
+    </Page>
+    <Page Include="$(MSBuildThisFileDirectory)Windows_UI_Xaml\xLoadTests\xLoad_xBind.xaml">
+      <SubType>Designer</SubType>
+      <Generator>MSBuild:Compile</Generator>
+    </Page>
     <Page Include="$(MSBuildThisFileDirectory)Windows_UI_Xaml_Controls\BitmapIconTests\BitmapIcon_Generic.xaml">
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>
@@ -4368,6 +4384,18 @@
     <Compile Include="$(MSBuildThisFileDirectory)Windows_UI_Xaml\xBindTests\xBind_Functions.xaml.cs">
       <DependentUpon>xBind_Functions.xaml</DependentUpon>
     </Compile>
+    <Compile Include="$(MSBuildThisFileDirectory)Windows_UI_Xaml\xLoadTests\xLoad_FindName.xaml.cs">
+      <DependentUpon>xLoad_FindName.xaml</DependentUpon>
+    </Compile>
+    <Compile Include="$(MSBuildThisFileDirectory)Windows_UI_Xaml\xLoadTests\xLoad_Literal.xaml.cs">
+      <DependentUpon>xLoad_Literal.xaml</DependentUpon>
+    </Compile>
+    <Compile Include="$(MSBuildThisFileDirectory)Windows_UI_Xaml\xLoadTests\xLoad_Test_For_Leak.xaml.cs">
+      <DependentUpon>xLoad_Test_For_Leak.xaml</DependentUpon>
+    </Compile>
+    <Compile Include="$(MSBuildThisFileDirectory)Windows_UI_Xaml\xLoadTests\xLoad_xBind.xaml.cs">
+      <DependentUpon>xLoad_xBind.xaml</DependentUpon>
+    </Compile>
     <Compile Include="$(MSBuildThisFileDirectory)Windows_UI_Xaml_Controls\BorderTests\Border_Clipped_Change_Property.xaml.cs">
       <DependentUpon>Border_Clipped_Change_Property.xaml</DependentUpon>
     </Compile>

src/SamplesApp/UITests.Shared/Windows_UI_Xaml/xLoadTests/xLoad_FindName.xaml

@@ -0,0 +1,19 @@
+<UserControl
+    x:Class="UITests.Windows_UI_Xaml.xLoadTests.xLoad_FindName"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:local="using:UITests.Windows_UI_Xaml.xLoadTests"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    mc:Ignorable="d"
+    d:DesignHeight="300"
+    d:DesignWidth="400">
+
+	<StackPanel>
+		<TextBlock Text="Clicking on the Load button should make a Green box appear in the Red border"/>
+		<Button Content="Load" x:Name="LoadButton"/>
+		<Border BorderBrush="Red" BorderThickness="1" Width="60" Height="60">
+			<Border x:Name="LoadBorder" Width="50" Height="50" Background="Green" x:Load="False"/>
+		</Border>
+	</StackPanel>
+</UserControl>

src/SamplesApp/UITests.Shared/Windows_UI_Xaml/xLoadTests/xLoad_FindName.xaml.cs

@@ -0,0 +1,35 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Runtime.InteropServices.WindowsRuntime;
+using Uno.UI.Samples.Controls;
+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 User Control item template is documented at https://go.microsoft.com/fwlink/?LinkId=234236
+
+namespace UITests.Windows_UI_Xaml.xLoadTests
+{
+	[Sample("xLoad", Name = "xLoad_FindName")]
+	public sealed partial class xLoad_FindName : UserControl
+    {
+        public xLoad_FindName()
+        {
+            this.InitializeComponent();
+			LoadButton.Click += LoadButton_Click;
+        }
+
+		private void LoadButton_Click(object sender, RoutedEventArgs e)
+		{
+			FindName("LoadBorder");
+		}
+	}
+}

src/SamplesApp/UITests.Shared/Windows_UI_Xaml/xLoadTests/xLoad_Literal.xaml

@@ -0,0 +1,23 @@
+<UserControl
+    x:Class="UITests.Windows_UI_Xaml.xLoadTests.xLoad_Literal"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:local="using:UITests.Windows_UI_Xaml.xLoadTests"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    mc:Ignorable="d"
+    d:DesignHeight="300"
+    d:DesignWidth="400">
+
+	<StackPanel>
+		<TextBlock Text="Should see two Red borders, the top one should be empty, the bottom one should contain a Green box"/>
+		<TextBlock Margin="0, 10, 0, 0" Text="Load = False" HorizontalAlignment="Center"/>
+		<Border BorderBrush="Red" BorderThickness="1" Width="60" Height="60">
+			<Border x:Name="LoadBorderFalse" Width="50" Height="50" Background="Green" x:Load="False"/>
+		</Border>
+		<TextBlock Margin="0, 10, 0, 0" Text="Load = True" HorizontalAlignment="Center"/>
+		<Border BorderBrush="Red" BorderThickness="1" Width="60" Height="60">
+			<Border x:Name="LoadBorderTrue" Width="50" Height="50" Background="Green" x:Load="True"/>
+		</Border>
+	</StackPanel>
+</UserControl>

src/SamplesApp/UITests.Shared/Windows_UI_Xaml/xLoadTests/xLoad_Literal.xaml.cs

@@ -0,0 +1,29 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Runtime.InteropServices.WindowsRuntime;
+using Uno.UI.Samples.Controls;
+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 User Control item template is documented at https://go.microsoft.com/fwlink/?LinkId=234236
+
+namespace UITests.Windows_UI_Xaml.xLoadTests
+{
+	[Sample("xLoad", Name = "xLoad_Literal")]
+	public sealed partial class xLoad_Literal : UserControl
+    {
+        public xLoad_Literal()
+        {
+            this.InitializeComponent();
+        }
+    }
+}

src/SamplesApp/UITests.Shared/Windows_UI_Xaml/xLoadTests/xLoad_Test_For_Leak.xaml

@@ -0,0 +1,17 @@
+<UserControl
+    x:Class="UITests.Windows_UI_Xaml.xLoadTests.xLoad_Test_For_Leak"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:local="using:UITests.Windows_UI_Xaml.xLoadTests"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    mc:Ignorable="d"
+    d:DesignHeight="300"
+    d:DesignWidth="400">
+
+    <Grid>
+		<Border x:Name="outerBorder" BorderBrush="Red" BorderThickness="1" Width="60" Height="60">
+			<Border x:Name="LoadBorder" Width="50" Height="50" Background="Green" x:Load="{x:Bind IsLoad, Mode=OneWay}" />
+		</Border>
+	</Grid>
+</UserControl>

src/SamplesApp/UITests.Shared/Windows_UI_Xaml/xLoadTests/xLoad_Test_For_Leak.xaml.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Runtime.InteropServices.WindowsRuntime;
+using Uno.UI.Samples.Controls;
+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 User Control item template is documented at https://go.microsoft.com/fwlink/?LinkId=234236
+
+namespace UITests.Windows_UI_Xaml.xLoadTests
+{
+	[Sample("xLoad", Name = "xLoad_Test_For_Leak")]
+	public sealed partial class xLoad_Test_For_Leak : UserControl
+    {
+		public bool IsLoad
+		{
+			get { return (bool)GetValue(IsLoadProperty); }
+			set { SetValue(IsLoadProperty, value); }
+		}
+
+		// Using a DependencyProperty as the backing store for IsLoad.  This enables animation, styling, binding, etc...
+		public static readonly DependencyProperty IsLoadProperty =
+			DependencyProperty.Register("IsLoad", typeof(bool), typeof(xLoad_Test_For_Leak), new PropertyMetadata(false));
+
+		public xLoad_Test_For_Leak()
+        {
+            this.InitializeComponent();
+
+			IsLoad = true;
+        }
+    }
+}

src/SamplesApp/UITests.Shared/Windows_UI_Xaml/xLoadTests/xLoad_xBind.xaml

@@ -0,0 +1,18 @@
+<UserControl
+    x:Class="UITests.Windows_UI_Xaml.xLoadTests.xLoad_xBind"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:local="using:UITests.Windows_UI_Xaml.xLoadTests"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    mc:Ignorable="d"
+    d:DesignHeight="300"
+    d:DesignWidth="400">
+
+	<StackPanel>
+		<CheckBox Content="Is Loaded" x:Name="LoadCheckBox" Margin="30" IsChecked="{x:Bind IsLoad, Mode=TwoWay}" />
+		<Border BorderBrush="Red" BorderThickness="1" Width="60" Height="60">
+			<Border x:Name="LoadBorder" Width="50" Height="50" Background="Green" x:Load="{x:Bind IsLoad, Mode=OneWay}" />
+		</Border>
+	</StackPanel>
+</UserControl>

src/SamplesApp/UITests.Shared/Windows_UI_Xaml/xLoadTests/xLoad_xBind.xaml.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Runtime.InteropServices.WindowsRuntime;
+using Uno.UI.Samples.Controls;
+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 User Control item template is documented at https://go.microsoft.com/fwlink/?LinkId=234236
+
+namespace UITests.Windows_UI_Xaml.xLoadTests
+{
+	[Sample("xLoad", Name = "xLoad_xBind")]
+	public sealed partial class xLoad_xBind : UserControl
+    {
+		public bool IsLoad
+		{
+			get { return (bool)GetValue(IsLoadProperty); }
+			set { SetValue(IsLoadProperty, value); }
+		}
+
+		// Using a DependencyProperty as the backing store for IsLoad.  This enables animation, styling, binding, etc...
+		public static readonly DependencyProperty IsLoadProperty =
+			DependencyProperty.Register("IsLoad", typeof(bool), typeof(xLoad_xBind), new PropertyMetadata(false));
+
+		public xLoad_xBind()
+        {
+            this.InitializeComponent();
+        }
+    }
+}

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

@@ -8,15 +8,23 @@ namespace Uno.UI.SourceGenerators.XamlGenerator
 {
 	internal class NameScope
 	{
-		public NameScope(string name)
+		public NameScope(string @namespace, string className)
 		{
-			this.Name = name;
+			Namespace = @namespace ?? string.Empty;
+			ClassName = className;
 		}
 
-		public string Name { get; private set; }
+		public string Name => $"{Namespace.Replace(".", "")}{ClassName}";
+		public string Namespace { get; private set; }
+		public string ClassName { get; private set; }
 
 		public List<BackingFieldDefinition> BackingFields { get; } = new List<BackingFieldDefinition>();
 
+		/// <summary>
+		/// Lists the ElementStub builder holder variables used to pin references for implicit pinning platforms
+		/// </summary>
+		public List<string> ElementStubHolders { get; } = new List<string>();
+
 		public HashSet<string> ReferencedElementNames { get; } = new HashSet<string>();
 
 		public Dictionary<string, Subclass> Subclasses { get; } = new Dictionary<string, Subclass>();

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

@@ -264,22 +264,22 @@ private bool IsFrameworkElement(XamlType xamlType)
 
 		private bool IsDependencyObject(XamlType xamlType)
 		{
-			return IsType(xamlType, XamlConstants.Types.DependencyObject);
+			return IsType(xamlType, _dependencyObjectSymbol);
 		}
 
 		private bool IsAndroidView(XamlType xamlType)
 		{
-			return IsType(xamlType, "Android.Views.View");
+			return IsType(xamlType, _androidViewSymbol);
 		}
 
 		private bool IsIOSUIView(XamlType xamlType)
 		{
-			return IsType(xamlType, "UIKit.UIView");
+			return IsType(xamlType, _iOSViewSymbol);
 		}
 
 		private bool IsMacOSNSView(XamlType xamlType)
 		{
-			return IsType(xamlType, "AppKit.NSView");
+			return IsType(xamlType, _appKitViewSymbol);
 		}
 
 		/// <summary>