Add native control host support

src/Web/Avalonia.Web.Sample/Avalonia.Web.Sample.csproj

@@ -30,6 +30,7 @@
   <ItemGroup>
     <WasmExtraFilesToDeploy Include="index.html" />
     <WasmExtraFilesToDeploy Include="main.js" />
+    <WasmExtraFilesToDeploy Include="embed.js" />
     <WasmExtraFilesToDeploy Include="favicon.ico" />
     <WasmExtraFilesToDeploy Include="Logo.svg" />
     <WasmExtraFilesToDeploy Include="app.css" />

src/Web/Avalonia.Web.Sample/EmbedSample.Browser.cs

@@ -0,0 +1,44 @@
+using System;
+using System.Runtime.InteropServices.JavaScript;
+
+using Avalonia;
+using Avalonia.Platform;
+using Avalonia.Web;
+
+using ControlCatalog.Pages;
+
+namespace ControlCatalog.Web;
+
+public class EmbedSampleWeb : INativeDemoControl
+{
+    public IPlatformHandle CreateControl(bool isSecond, IPlatformHandle parent, Func<IPlatformHandle> createDefault)
+    {
+        if (isSecond)
+        {
+            var iframe = EmbedInterop.CreateElement("iframe");
+            iframe.SetProperty("src", "https://www.youtube.com/embed/kZCIporjJ70");
+
+            return new JSObjectControlHandle(iframe);
+        }
+        else
+        {
+            var defaultHandle = (JSObjectControlHandle)createDefault();
+
+            _ = JSHost.ImportAsync("embed.js", "./embed.js").ContinueWith(_ =>
+            {
+                EmbedInterop.AddAppButton(defaultHandle.Object);
+            });
+
+            return defaultHandle;
+        }
+    }
+}
+
+internal static partial class EmbedInterop
+{
+    [JSImport("globalThis.document.createElement")]
+    public static partial JSObject CreateElement(string tagName);
+
+    [JSImport("addAppButton", "embed.js")]
+    public static partial void AddAppButton(JSObject parentObject);
+}

src/Web/Avalonia.Web.Sample/Program.cs

@@ -1,12 +1,17 @@
 using Avalonia;
 using Avalonia.Web;
 using ControlCatalog;
+using ControlCatalog.Web;
 
 internal partial class Program
 {
     private static void Main(string[] args)
     {
-        BuildAvaloniaApp().SetupBrowserApp("out");
+        BuildAvaloniaApp()
+            .AfterSetup(_ =>
+            {
+                ControlCatalog.Pages.EmbedSample.Implementation = new EmbedSampleWeb();
+            }).SetupBrowserApp("out");
     }
 
     public static AppBuilder BuildAvaloniaApp()

src/Web/Avalonia.Web.Sample/embed.js

@@ -0,0 +1,11 @@
+export function addAppButton(parent) {
+    var button = globalThis.document.createElement('button');
+    button.innerText = 'Hello world';
+    var clickCount = 0;
+    button.onclick = () => {
+        clickCount++;
+        button.innerText = 'Click count ' + clickCount;
+    };
+    parent.appendChild(button);
+    return button;
+}

src/Web/Avalonia.Web/AvaloniaView.cs

@@ -333,8 +333,7 @@ namespace Avalonia.Web
 
         internal INativeControlHostImpl GetNativeControlHostImpl()
         {
-            throw new NotImplementedException();
-            //return _nativeControlHost ?? throw new InvalidOperationException("Blazor View wasn't initialized yet");
+            return new BrowserNativeControlHost(_nativeControlsContainer);
         }
 
         private void ForceBlit()

src/Web/Avalonia.Web/BrowserNativeControlHost.cs

@@ -0,0 +1,136 @@
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Runtime.InteropServices.JavaScript;
+
+using Avalonia.Controls.Platform;
+using Avalonia.Platform;
+using Avalonia.Web.Interop;
+
+namespace Avalonia.Web
+{
+    internal class BrowserNativeControlHost : INativeControlHostImpl
+    {
+        private readonly JSObject _hostElement;
+
+        public BrowserNativeControlHost(JSObject element)
+        {
+            _hostElement = element;
+        }
+
+        public INativeControlHostDestroyableControlHandle CreateDefaultChild(IPlatformHandle parent)
+        {
+            var element = NativeControlHostHelper.CreateDefaultChild(null);
+            return new JSObjectControlHandle(element);
+        }
+
+        public INativeControlHostControlTopLevelAttachment CreateNewAttachment(Func<IPlatformHandle, IPlatformHandle> create)
+        {
+            Attachment? a = null;
+            try
+            {
+                var child = create(new JSObjectControlHandle(_hostElement));
+                var attachmenetReference = NativeControlHostHelper.CreateAttachment();
+                // It has to be assigned to the variable before property setter is called so we dispose it on exception
+#pragma warning disable IDE0017 // Simplify object initialization
+                a = new Attachment(attachmenetReference, child);
+#pragma warning restore IDE0017 // Simplify object initialization
+                a.AttachedTo = this;
+                return a;
+            }
+            catch
+            {
+                a?.Dispose();
+                throw;
+            }
+        }
+
+        public INativeControlHostControlTopLevelAttachment CreateNewAttachment(IPlatformHandle handle)
+        {
+            var attachmenetReference = NativeControlHostHelper.CreateAttachment();
+            var a = new Attachment(attachmenetReference, handle);
+            a.AttachedTo = this;
+            return a;
+        }
+
+        public bool IsCompatibleWith(IPlatformHandle handle) => handle is JSObjectControlHandle;
+
+        private class Attachment : INativeControlHostControlTopLevelAttachment
+        {
+            private const string InitializeWithChildHandleSymbol = "InitializeWithChildHandle";
+            private const string AttachToSymbol = "AttachTo";
+            private const string ShowInBoundsSymbol = "ShowInBounds";
+            private const string HideWithSizeSymbol = "HideWithSize";
+            private const string ReleaseChildSymbol = "ReleaseChild";
+
+            private JSObject? _native;
+            private BrowserNativeControlHost? _attachedTo;
+
+            public Attachment(JSObject native, IPlatformHandle handle)
+            {
+                _native = native;
+                NativeControlHostHelper.InitializeWithChildHandle(_native, ((JSObjectControlHandle)handle).Object);
+            }
+
+            public void Dispose()
+            {
+                if (_native != null)
+                {
+                    NativeControlHostHelper.ReleaseChild(_native);
+                    _native.Dispose();
+                    _native = null;
+                }
+            }
+
+            public INativeControlHostImpl? AttachedTo
+            {
+                get => _attachedTo!;
+                set
+                {
+                    CheckDisposed();
+
+                    var host = (BrowserNativeControlHost?)value;
+                    if (host == null)
+                    {
+                        NativeControlHostHelper.AttachTo(_native, null);
+                    }
+                    else
+                    {
+                        NativeControlHostHelper.AttachTo(_native, host._hostElement);
+                    }
+                    _attachedTo = host;
+                }
+            }
+
+            public bool IsCompatibleWith(INativeControlHostImpl host) => host is BrowserNativeControlHost;
+
+            public void HideWithSize(Size size)
+            {
+                CheckDisposed();
+                if (_attachedTo == null)
+                    return;
+
+                NativeControlHostHelper.HideWithSize(_native, Math.Max(1, size.Width), Math.Max(1, size.Height));
+            }
+
+            public void ShowInBounds(Rect bounds)
+            {
+                CheckDisposed();
+
+                if (_attachedTo == null)
+                    throw new InvalidOperationException("Native control isn't attached to a toplevel");
+
+                bounds = new Rect(bounds.X, bounds.Y, Math.Max(1, bounds.Width),
+                    Math.Max(1, bounds.Height));
+
+                NativeControlHostHelper.ShowInBounds(_native, bounds.X, bounds.Y, bounds.Width, bounds.Height);
+            }
+
+            [MemberNotNull(nameof(_native))]
+            private void CheckDisposed()
+            {
+                if (_native == null)
+                    throw new ObjectDisposedException(nameof(Attachment));
+            }
+        }
+    }
+}

src/Web/Avalonia.Web/BrowserTopLevelImpl.cs

@@ -35,13 +35,11 @@ namespace Avalonia.Web
             AcrylicCompensationLevels = new AcrylicPlatformCompensationLevels(1, 1, 1);
             _touchDevice = new TouchDevice();
             _penDevice = new PenDevice();
+            NativeControlHost = _avaloniaView.GetNativeControlHostImpl();
         }
 
         public ulong Timestamp => (ulong)_sw.ElapsedMilliseconds;
 
-
-        
-
         public void SetClientSize(Size newSize, double dpi)
         {
             if (Math.Abs(RenderScaling - dpi) > 0.0001)
@@ -222,7 +220,7 @@ namespace Avalonia.Web
 
         public ITextInputMethodImpl TextInputMethod => _avaloniaView;
 
-        public INativeControlHostImpl? NativeControlHost => _avaloniaView.GetNativeControlHostImpl();
+        public INativeControlHostImpl? NativeControlHost { get; }
         public IStorageProvider StorageProvider { get; } = new BrowserStorageProvider();
     }
 }

src/Web/Avalonia.Web/Interop/NativeControlHostHelper.cs

@@ -0,0 +1,28 @@
+using System;
+using System.Runtime.InteropServices.JavaScript;
+
+namespace Avalonia.Web.Interop;
+
+internal static partial class NativeControlHostHelper
+{
+    [JSImport("NativeControlHost.createDefaultChild", "avalonia.ts")]
+    internal static partial JSObject CreateDefaultChild(JSObject? parent);
+
+    [JSImport("NativeControlHost.createAttachment", "avalonia.ts")]
+    internal static partial JSObject CreateAttachment();
+
+    [JSImport("NativeControlHost.initializeWithChildHandle", "avalonia.ts")]
+    internal static partial void InitializeWithChildHandle(JSObject element, JSObject child);
+
+    [JSImport("NativeControlHost.attachTo", "avalonia.ts")]
+    internal static partial void AttachTo(JSObject element, JSObject? host);
+
+    [JSImport("NativeControlHost.showInBounds", "avalonia.ts")]
+    internal static partial void ShowInBounds(JSObject element, double x, double y, double width, double height);
+
+    [JSImport("NativeControlHost.hideWithSize", "avalonia.ts")]
+    internal static partial void HideWithSize(JSObject element, double width, double height);
+
+    [JSImport("NativeControlHost.releaseChild", "avalonia.ts")]
+    internal static partial void ReleaseChild(JSObject element);
+}

src/Web/Avalonia.Web/JSObjectControlHandle.cs

@@ -0,0 +1,30 @@
+using System;
+using System.Runtime.InteropServices.JavaScript;
+
+using Avalonia.Controls.Platform;
+
+namespace Avalonia.Web;
+
+public class JSObjectControlHandle : INativeControlHostDestroyableControlHandle
+{
+    internal const string ElementReferenceDescriptor = "JSObject";
+
+    public JSObjectControlHandle(JSObject reference)
+    {
+        Object = reference;
+    }
+
+    public JSObject Object { get; }
+
+    public IntPtr Handle => throw new NotSupportedException();
+
+    public string? HandleDescriptor => ElementReferenceDescriptor;
+
+    public void Destroy()
+    {
+        if (Object is JSObject inProcess && !inProcess.IsDisposed)
+        {
+            inProcess.Dispose();
+        }
+    }
+}

src/Web/Avalonia.Web/webapp/modules/avalonia.ts

@@ -1,19 +1,20 @@
 import { RuntimeAPI } from "../types/dotnet";
 import { SizeWatcher, DpiWatcher, Canvas } from "./avalonia/canvas";
-
 import { InputHelper } from "./avalonia/input";
 import { AvaloniaDOM } from "./avalonia/dom";
 import { Caniuse } from "./avalonia/caniuse";
 import { StreamHelper } from "./avalonia/stream";
+import { NativeControlHost } from "./avalonia/NativeControlHost";
 
 export async function createAvaloniaRuntime(api: RuntimeAPI): Promise<void> {
     api.setModuleImports("avalonia.ts", {
+        Caniuse,
         Canvas,
         InputHelper,
         SizeWatcher,
         DpiWatcher,
         AvaloniaDOM,
-        Caniuse,
-        StreamHelper
+        StreamHelper,
+        NativeControlHost
     });
 }

src/Web/Avalonia.Web/webapp/modules/avalonia/nativeControlHost.ts

@@ -0,0 +1,55 @@
+class NativeControlHostTopLevelAttachment {
+    _child?: HTMLElement;
+    _host?: HTMLElement;
+}
+
+export class NativeControlHost {
+    public static createDefaultChild(parent?: HTMLElement): HTMLElement {
+        return document.createElement("div");
+    }
+
+    public static createAttachment(): NativeControlHostTopLevelAttachment {
+        return new NativeControlHostTopLevelAttachment();
+    }
+
+    public static initializeWithChildHandle(element: NativeControlHostTopLevelAttachment, child: HTMLElement): void {
+        element._child = child;
+        element._child.style.position = "absolute";
+    }
+
+    public static attachTo(element: NativeControlHostTopLevelAttachment, host?: HTMLElement): void {
+        if (element._host && element._child) {
+            element._host.removeChild(element._child);
+        }
+
+        element._host = host;
+
+        if (element._host && element._child) {
+            element._host.appendChild(element._child);
+        }
+    }
+
+    public static showInBounds(element: NativeControlHostTopLevelAttachment, x: number, y: number, width: number, height: number): void {
+        if (element._child) {
+            element._child.style.top = `${y}px`;
+            element._child.style.left = `${x}px`;
+            element._child.style.width = `${width}px`;
+            element._child.style.height = `${height}px`;
+            element._child.style.display = "block";
+        }
+    }
+
+    public static hideWithSize(element: NativeControlHostTopLevelAttachment, width: number, height: number): void {
+        if (element._child) {
+            element._child.style.width = `${width}px`;
+            element._child.style.height = `${height}px`;
+            element._child.style.display = "none";
+        }
+    }
+
+    public static releaseChild(element: NativeControlHostTopLevelAttachment): void {
+        if (element._child) {
+            element._child = undefined;
+        }
+    }
+}