Refactor WASM input and dom-callbacks to work with multithreading

samples/ControlCatalog.Browser/ControlCatalog.Browser.csproj

@@ -1,9 +1,7 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk.WebAssembly">
   <PropertyGroup>
     <TargetFramework>$(AvsCurrentBrowserTargetFramework)</TargetFramework>
-    <RuntimeIdentifier>browser-wasm</RuntimeIdentifier>
-    <WasmMainJSPath>wwwroot/main.js</WasmMainJSPath>
-    <OutputType>Exe</OutputType>
+    <WasmEnableThreads>false</WasmEnableThreads>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <DebuggerSupport>true</DebuggerSupport>
     <WasmDebugLevel>5</WasmDebugLevel>
@@ -22,10 +20,6 @@
     <AdditionalUpToDateCheckInput Include="../../src/Browser/Avalonia.Browser/**/*" Visible="false"/>
   </ItemGroup>
 
-  <ItemGroup>
-    <WasmExtraFilesToDeploy Include="wwwroot/**" />
-  </ItemGroup>
-
   <Import Project="../../src/Browser/Avalonia.Browser/build/Avalonia.Browser.props" />
   <Import Project="../../src/Browser/Avalonia.Browser/build/Avalonia.Browser.targets" />
 </Project>

samples/ControlCatalog.Browser/EmbedSample.Browser.cs

@@ -29,7 +29,7 @@ public IPlatformHandle CreateControl(bool isSecond, IPlatformHandle parent, Func
 
             static async void AddButton(JSObject parent)
             {
-                await JSHost.ImportAsync("embed.js", "./embed.js");
+                await JSHost.ImportAsync("embed.js", "../embed.js");
                 EmbedInterop.AddAppButton(parent);
             } 
         }

samples/ControlCatalog.Browser/Program.cs

@@ -33,10 +33,13 @@ await BuildAvaloniaApp()
             })
             .StartBrowserAppAsync("out", options);
 
-        if (Application.Current!.ApplicationLifetime is ISingleTopLevelApplicationLifetime lifetime)
+        Dispatcher.UIThread.Invoke(() =>
         {
-            lifetime.TopLevel!.RendererDiagnostics.DebugOverlays = RendererDebugOverlays.Fps;
-        }
+            if (Application.Current!.ApplicationLifetime is ISingleTopLevelApplicationLifetime lifetime)
+            {
+                lifetime.TopLevel!.RendererDiagnostics.DebugOverlays = RendererDebugOverlays.Fps;
+            }
+        });
     }
 
     // Test with multiple AvaloniaView at once. 

src/Browser/Avalonia.Browser/Avalonia.Browser.csproj

@@ -54,4 +54,10 @@
     <InternalsVisibleTo Include="Avalonia.Browser.Blazor, PublicKey=$(AvaloniaPublicKey)" />
   </ItemGroup>
 
+  <ItemGroup>
+    <Compile Include="..\..\Shared\RawEventGrouping.cs">
+      <Link>RawEventGrouping.cs</Link>
+    </Compile>
+  </ItemGroup>
+
 </Project>

src/Browser/Avalonia.Browser/AvaloniaView.cs

@@ -12,7 +12,7 @@ public class AvaloniaView
 
         /// <param name="divId">ID of the html element where avalonia content should be rendered.</param>
         public AvaloniaView(string divId)
-            : this(DomHelper.GetElementById(divId) ??
+            : this(DomHelper.GetElementById(divId, BrowserWindowingPlatform.GlobalThis) ??
                    throw new Exception($"Element with id '{divId}' was not found in the html document."))
         {
         }
@@ -47,7 +47,7 @@ public AvaloniaView(JSObject host)
                 // Try to get local splash-screen of the specific host.
                 // If couldn't find - get global one by ID for compatibility.
                 var splash = DomHelper.GetElementsByClassName("avalonia-splash", host)
-                             ?? DomHelper.GetElementById("avalonia-splash");
+                             ?? DomHelper.GetElementById("avalonia-splash", BrowserWindowingPlatform.GlobalThis);
                 if (splash is not null)
                 {
                     DomHelper.AddCssClass(splash, "splash-close");

src/Browser/Avalonia.Browser/BrowserActivatableLifetime.cs

@@ -1,36 +1,20 @@
-using System;
 using Avalonia.Browser.Interop;
 using Avalonia.Controls.ApplicationLifetimes;
-using Avalonia.Threading;
 
 namespace Avalonia.Browser;
 
-internal class BrowserActivatableLifetime : IActivatableLifetime
+internal class BrowserActivatableLifetime : ActivatableLifetimeBase
 {
-    public BrowserActivatableLifetime()
+    public void OnVisibilityStateChanged(string visibilityState)
     {
-        bool? initiallyVisible = InputHelper.SubscribeVisibilityChange(visible =>
+        var visible = visibilityState == "visible";
+        if (visible)
         {
-            initiallyVisible = null;
-            (visible ? Activated : Deactivated)?.Invoke(this, new ActivatedEventArgs(ActivationKind.Background));
-        });
-
-        // Trigger Activated as an initial state, if web page is visible, and wasn't hidden during initialization.
-        if (initiallyVisible == true)
+            OnActivated(ActivationKind.Background);
+        }
+        else
         {
-            _ = Dispatcher.UIThread.InvokeAsync(() =>
-            {
-                if (initiallyVisible == true)
-                {
-                    Activated?.Invoke(this, new ActivatedEventArgs(ActivationKind.Background));
-                }
-            }, DispatcherPriority.Background);
+            OnDeactivated(ActivationKind.Background);
         }
     }
-
-    public event EventHandler<ActivatedEventArgs>? Activated;
-    public event EventHandler<ActivatedEventArgs>? Deactivated;
-
-    public bool TryLeaveBackground() => false;
-    public bool TryEnterBackground() => false;
 }

src/Browser/Avalonia.Browser/BrowserAppBuilder.cs

@@ -1,8 +1,10 @@
 using System;
 using System.Collections.Generic;
+using System.Threading;
 using System.Threading.Tasks;
 using Avalonia.Browser.Interop;
 using Avalonia.Browser.Rendering;
+using Avalonia.Controls;
 using Avalonia.Metadata;
 
 namespace Avalonia.Browser;
@@ -53,6 +55,12 @@ public record BrowserPlatformOptions
     /// For more details, see https://github.com/jimmywarting/native-file-system-adapter#a-note-when-downloading-with-the-polyfilled-version.
     /// </summary>
     public bool PreferFileDialogPolyfill { get; set; }
+
+    /// <summary>
+    /// Defines if Avalonia should create a controlled dispatcher loop on the web worker thread.
+    /// If used only when WasmEnableThreads is set to true. Default value is true.
+    /// </summary>
+    public bool? PreferManagedThreadDispatcher { get; set; } = true;
 }
 
 public static class BrowserAppBuilder
@@ -63,8 +71,9 @@ public static class BrowserAppBuilder
     /// <param name="builder">Application builder.</param>
     /// <param name="mainDivId">ID of the html element where avalonia content should be rendered.</param>
     /// <param name="options">Browser backend specific options.</param>
-    public static async Task StartBrowserAppAsync(this AppBuilder builder, string mainDivId,
-        BrowserPlatformOptions? options = null)
+    public static async Task StartBrowserAppAsync(
+        this AppBuilder builder,
+        string mainDivId, BrowserPlatformOptions? options = null)
     {
         if (mainDivId is null)
         {
@@ -78,8 +87,35 @@ public static async Task StartBrowserAppAsync(this AppBuilder builder, string ma
             .AfterApplicationSetup(_ =>
             {
                 lifetime.View = new AvaloniaView(mainDivId);
-            })
-            .SetupWithLifetime(lifetime);
+            });
+
+        if (BrowserWindowingPlatform.IsManagedDispatcherEnabled)
+        {
+            var tcs = new TaskCompletionSource();
+            var thread = new Thread(() =>
+            {
+                try
+                {
+                    builder
+                        .SetupWithLifetime(lifetime);
+                    tcs.TrySetResult();
+                    builder.Instance!.Run(CancellationToken.None);
+                }
+                catch (Exception ex)
+                {
+                    tcs.TrySetException(ex);
+                }
+            });
+#pragma warning disable CA1416
+            thread.Start();
+#pragma warning restore CA1416
+            await tcs.Task;
+        }
+        else
+        {
+            builder
+                .SetupWithLifetime(lifetime);
+        }
     }
 
     /// <summary>
@@ -102,12 +138,15 @@ public static async Task SetupBrowserAppAsync(this AppBuilder builder, BrowserPl
 
     internal static async Task<AppBuilder> PreSetupBrowser(AppBuilder builder, BrowserPlatformOptions? options)
     {
-        options ??= new BrowserPlatformOptions();
+        options ??= AvaloniaLocator.Current.GetService<BrowserPlatformOptions>() ?? new BrowserPlatformOptions();
         options.FrameworkAssetPathResolver ??= fileName => $"./{fileName}";
 
         AvaloniaLocator.CurrentMutable.Bind<BrowserPlatformOptions>().ToConstant(options);
 
         await AvaloniaModule.ImportMain();
+
+        BrowserWindowingPlatform.GlobalThis = DomHelper.GetGlobalThis();
+
         if (BrowserWindowingPlatform.IsThreadingEnabled)
         {
             await RenderWorker.InitializeAsync();