Compressed layout is back (maybe?)

src/Controls/src/Core/Layout/Layout.cs

@@ -13,7 +13,7 @@ namespace Microsoft.Maui.Controls
 	/// Base class for layouts that allow you to arrange and group UI controls in your application.
 	/// </summary>
 	[ContentProperty(nameof(Children))]
-	public abstract partial class Layout : View, Maui.ILayout, IList<IView>, IBindableLayout, IPaddingElement, IVisualTreeElement, ISafeAreaView, IInputTransparentContainerElement
+	public abstract partial class Layout : View, Maui.ILayout, IList<IView>, IBindableLayout, IPaddingElement, IVisualTreeElement, ISafeAreaView, IInputTransparentContainerElement, ICompressedLayout
 	{
 		protected ILayoutManager _layoutManager;
 
@@ -79,6 +79,8 @@ public IView this[int index]
 				OnUpdate(index, value, old);
 			}
 		}
+
+		bool ICompressedLayout.IsHeadless => CompressedLayout.GetIsHeadless(this);
 
 		/// <summary>Bindable property for <see cref="IsClippedToBounds"/>.</summary>
 		public static readonly BindableProperty IsClippedToBoundsProperty =

src/Controls/src/Core/Platform/GestureManager/GestureManager.cs

@@ -76,7 +76,12 @@ void SetupGestureManager()
 			if (GesturePlatformManager != null)
 				return;
 
+#if PLATFORM
+			GesturePlatformManager = handler is IPlatformViewHandler ? new GesturePlatformManager(handler) : null;
+#else
 			GesturePlatformManager = new GesturePlatformManager(handler);
+#endif
+
 			_handler = handler;
 			_containerView = handler.ContainerView;
 			_platformView = handler.PlatformView;

src/Controls/tests/TestCases.HostApp/Issues/Issue24532.xaml

@@ -0,0 +1,33 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             x:Class="Maui.Controls.Sample.Issues.Issue24532"
+             Title="Issue24532">
+
+    <Grid Padding="24" RowDefinitions="Auto,*" RowSpacing="8">
+      <Button x:Name="StartButton" Clicked="ButtonClicked" Text="Start" AutomationId="StartButton" />
+
+      <ScrollView Grid.Row="1">
+        <VerticalStackLayout x:Name="BindableContainer" BindableLayout.ItemsSource="{Binding Models}">
+          <BindableLayout.ItemTemplate>
+            <DataTemplate>
+              <Grid RowDefinitions="Auto,Auto,Auto" CompressedLayout.IsHeadless="True">
+                <Label Text="{Binding Header}" />
+                <Label Text="{Binding Content}" Grid.Row="1" />
+                <VerticalStackLayout Grid.Row="2" BindableLayout.ItemsSource="{Binding SubModels}" CompressedLayout.IsHeadless="True">
+                  <BindableLayout.ItemTemplate>
+                    <DataTemplate>
+                      <VerticalStackLayout CompressedLayout.IsHeadless="True">
+                        <Label Text="{Binding Header}" />
+                        <Label Text="{Binding Content}" AutomationId="{Binding AutomationId}" />
+                      </VerticalStackLayout>
+                    </DataTemplate>
+                  </BindableLayout.ItemTemplate>
+                </VerticalStackLayout>
+              </Grid>
+            </DataTemplate>
+          </BindableLayout.ItemTemplate>
+        </VerticalStackLayout>
+      </ScrollView>
+    </Grid>
+</ContentPage>

src/Controls/tests/TestCases.HostApp/Issues/Issue24532.xaml.cs

@@ -0,0 +1,144 @@
+using System;
+using System.Collections.ObjectModel;
+using System.Diagnostics;
+using Microsoft.Maui;
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Controls.Xaml;
+
+#if __IOS__ || MACCATALYST
+using PlatformView = UIKit.UIView;
+#elif __ANDROID__
+using PlatformView = Android.Views.View;
+#elif WINDOWS
+using PlatformView = Microsoft.UI.Xaml.FrameworkElement;
+#elif TIZEN
+using PlatformView = Tizen.NUI.BaseComponents.View;
+#elif (NETSTANDARD || !PLATFORM)
+using PlatformView = System.Object;
+#endif
+
+namespace Maui.Controls.Sample.Issues;
+
+[XamlCompilation(XamlCompilationOptions.Compile)]
+[Issue(IssueTracker.Github, 24532, "Rendering performance", PlatformAffected.All)]
+public partial class Issue24532 : ContentPage
+{
+	public List<Model> Models { get; set; }
+
+	public Issue24532()
+	{
+		Models = GenerateOneItem("Test0");
+		BindingContext = this;
+		InitializeComponent();
+	}
+
+	private async void ButtonClicked(object sender, EventArgs e)
+	{
+		var stopwatch = new Stopwatch();
+
+		var platformView = (PlatformView)BindableContainer.Handler!.PlatformView;
+
+		var capturedTimes = new List<long[]>();
+
+		var test1Models = GenerateItems("Test1", 70);
+		var test2Models = GenerateItems("Test2", 40);
+		var resetModel = GenerateOneItem("Test0");
+
+		for (var i = 0; i < 5; i++)
+		{
+			await Task.Delay(100);
+
+			Models = test1Models;
+			stopwatch.Restart();
+			OnPropertyChanged(nameof(Models));
+			await WaitForAutomationId(platformView, "Test1");
+			stopwatch.Stop();
+			var t1 = stopwatch.ElapsedMilliseconds;
+
+			await Task.Delay(100);
+
+			Models = test2Models;
+			stopwatch.Restart();
+			OnPropertyChanged(nameof(Models));
+			await WaitForAutomationId(platformView, "Test2");
+			stopwatch.Stop();
+			var t2 = stopwatch.ElapsedMilliseconds;
+
+			await Task.Delay(100);
+
+			stopwatch.Restart();
+			BindableContainer.Clear();
+			Models = resetModel;
+			OnPropertyChanged(nameof(Models));
+			await WaitForAutomationId(platformView, "Test0");
+			stopwatch.Stop();
+			var t3 = stopwatch.ElapsedMilliseconds;
+
+			capturedTimes.Add([t1, t2, t3]);
+		}
+
+		StartButton.Text =
+			$"{capturedTimes.Average(t => t[0])},{capturedTimes.Average(t => t[1])},{capturedTimes.Average(t => t[2])}";
+	}
+
+	async Task WaitForAutomationId(PlatformView platformView, string automationId)
+	{
+		var found = false;
+
+		while (!found)
+		{
+			await Task.Delay(20);
+#if IOS
+			int length;
+			while ((length = platformView.Subviews.Length) > 0) { platformView = platformView.Subviews[length - 1]; }
+			found = platformView.AccessibilityIdentifier == automationId;
+#elif ANDROID
+			int length;
+			while ((length = (platformView as Android.Views.ViewGroup)?.ChildCount ?? 0) > 0) { platformView = ((Android.Views.ViewGroup)platformView!).GetChildAt(length - 1); }
+			found = (platformView as Android.Widget.TextView)?.Text == automationId;
+#else
+			found = true;
+#endif
+		}
+	}
+
+	static List<Model> GenerateItems(string automationId, int count)
+	{
+		return
+		[
+			..Enumerable.Range(0, count).Select(i => new Model { Content = $"Content {i}", Header = $"Header {i}" }),
+			..GenerateOneItem(automationId)
+		];
+	}
+
+	static List<Model> GenerateOneItem(string automationId)
+	{
+		return
+		[
+			new Model
+			{
+				Content = automationId,
+				Header = automationId,
+				SubModels =
+				[
+					new SubModel { Content = automationId, Header = automationId, AutomationId = automationId }
+				]
+			}
+		];
+	}
+
+	public class Model : SubModel
+	{
+		public SubModel[] SubModels { get; set; } = Enumerable.Range(0, 10).Select(i => new SubModel
+		{
+			Content = $"SubContent {i}", Header = $"SubHeader {i}"
+		}).ToArray();
+	}
+
+	public class SubModel
+	{
+		public string Header { get; set; }
+		public string Content { get; set; }
+		public string AutomationId { get; set; }
+	}
+}

src/Controls/tests/TestCases.HostApp/Issues/Issue99999.xaml

@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             x:Class="Maui.Controls.Sample.Issues.Issue99999"
+             Title="Issue99999">
+
+  <Grid Padding="24" RowDefinitions="Auto,Auto" ColumnDefinitions="*,*,*,*,*" RowSpacing="16" ColumnSpacing="8">
+    <Entry x:Name="IndexEntry" Keyboard="Numeric" Placeholder="Index" />
+    <Button Text="Ins out" Clicked="OnInsOut" Grid.Row="0" Grid.Column="1" />
+    <Button Text="Rm out" Clicked="OnRmOut" Grid.Row="0" Grid.Column="2" />
+    <Button Text="Ins in" Clicked="OnInsIn" Grid.Row="0" Grid.Column="3" />
+    <Button Text="Rm in" Clicked="OnRmIn" Grid.Row="0" Grid.Column="4" />
+
+    <VerticalStackLayout x:Name="OuterLayout" Spacing="16" Grid.Row="1" Grid.ColumnSpan="5">
+      <Label Text="Text0" BackgroundColor="LightBlue" HeightRequest="20" />
+      <Label Text="Text1" BackgroundColor="LightBlue" HeightRequest="20" />
+      <VerticalStackLayout x:Name="InnerLayout" Padding="12" Spacing="8" CompressedLayout.IsHeadless="True">
+        <Label Text="Text2" BackgroundColor="LightGreen" HeightRequest="20" />
+        <Label Text="Text3" BackgroundColor="LightGreen" HeightRequest="20" />
+        <Label Text="Text4" BackgroundColor="LightGreen" HeightRequest="20" />
+      </VerticalStackLayout>
+      <Label Text="Text5" BackgroundColor="LightBlue" HeightRequest="20" />
+      <Label Text="Text6" BackgroundColor="LightBlue" HeightRequest="20" />
+    </VerticalStackLayout>
+  </Grid>
+</ContentPage>

src/Controls/tests/TestCases.HostApp/Issues/Issue99999.xaml.cs

@@ -0,0 +1,43 @@
+using System;
+using Microsoft.Maui;
+using Microsoft.Maui.Controls;
+using Microsoft.Maui.Controls.Xaml;
+
+namespace Maui.Controls.Sample.Issues;
+
+[XamlCompilation(XamlCompilationOptions.Compile)]
+[Issue(IssueTracker.Github, 99999, "CompressedLayout is not working", PlatformAffected.All)]
+
+public partial class Issue99999 : ContentPage
+{
+	int _count = 6;
+
+	public Issue99999()
+	{
+		InitializeComponent();
+	}
+
+	private void OnInsOut(object sender, EventArgs e)
+	{
+		var index = int.Parse(IndexEntry.Text);
+		OuterLayout.Insert(index, new Label { Text = $"Text{++_count}" });
+	}
+
+	private void OnRmOut(object sender, EventArgs e)
+	{
+		var index = int.Parse(IndexEntry.Text);
+		OuterLayout.RemoveAt(index);
+	}
+
+	private void OnInsIn(object sender, EventArgs e)
+	{
+		var index = int.Parse(IndexEntry.Text);
+		InnerLayout.Insert(index, new Label { Text = $"Text{++_count}" });
+	}
+
+	private void OnRmIn(object sender, EventArgs e)
+	{
+		var index = int.Parse(IndexEntry.Text);
+		InnerLayout.RemoveAt(index);
+	}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue24532.cs

@@ -0,0 +1,41 @@
+#if ANDROID || IOS || MACCATALYST
+using NUnit.Framework;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues
+{
+	public class Issue24532 : _IssuesUITest
+	{
+		public Issue24532(TestDevice device) : base(device) { }
+
+		public override string Issue => "Rendering performance";
+
+		[Test]
+		[Category(UITestCategories.Performance)]
+		public async Task RenderingPerformance()
+		{
+			var button = App.WaitForElement("StartButton");
+			App.Tap("StartButton");
+
+			string? text;
+			while (true)
+			{
+				text = button.GetText();
+				if (string.IsNullOrEmpty(text) || text == "Start")
+				{
+					await Task.Delay(1000);
+					continue;
+				}
+
+				break;
+			}
+
+			var times = text.Split(',');
+			Console.WriteLine(@$"First render: {times[0]}ms");
+			Console.WriteLine(@$"Binding context changed: {times[1]}ms");
+			Console.WriteLine(@$"Clear: {times[2]}ms");
+		}
+	}
+}
+#endif

src/Core/src/Core/ICompressedLayout.cs

@@ -0,0 +1,17 @@
+namespace Microsoft.Maui
+{
+
+	/// <summary>
+	/// Provides information about whether the ILayout is compressed.
+	/// </summary>
+	/// <remarks>
+	/// A compressed layout is not included in the platform tree.
+	/// </remarks>
+	internal interface ICompressedLayout
+	{
+		/// <summary>
+		/// Specifies whether the ILayout is compressed.
+		/// </summary>
+		bool IsHeadless { get; }
+	}
+}