Move adapter resizing from NativeWebView to NativeWebViewControlHost

samples/Avalonia.Controls.WebView.Samples/MainView.axaml.cs

@@ -397,7 +397,11 @@ private void GridWebViewDialogButton_OnClick(object? sender, RoutedEventArgs e)
             Source = Uri.TryCreate(GridWebViewSource.Text, UriKind.Absolute, out var source) ?
                 source :
                 new Uri("about:blank"),
-            Title = "Avalonia WebView Demo" 
+            Title = "Avalonia WebView Demo"
+        };
+        dialog.EnvironmentRequested += (_, args) =>
+        {
+            args.EnableDevTools = true;
         };
         dialog.Show();
     }

src/Avalonia.Controls.WebView.Core/Gtk/GtkX11WebViewAdapter.cs

@@ -16,6 +16,7 @@ internal sealed class GtkX11WebViewAdapter : GtkWebViewAdapter, IPlatformHandle
     private readonly IntPtr _x11Window;
     private IntPtr _windowHandle;
     private IntPtr _currentParent;
+    private PixelSize _sizeRequest;
 
     private GtkX11WebViewAdapter(GtkWebViewEnvironmentRequestedEventArgs environmentArgs) : base(environmentArgs)
     {
@@ -71,6 +72,21 @@ public override void SetParent(IPlatformHandle parent)
         }
     }
 
+    public override void SizeChanged(PixelSize containerSize)
+    {
+        if (containerSize.Width <= 0 || containerSize.Height <= 0)
+            return;
+
+        _sizeRequest = containerSize;
+        RunOnGlibThreadAsync(() =>
+        {
+            if (_windowHandle == IntPtr.Zero)
+                return;
+
+            gtk_window_resize(_windowHandle, _sizeRequest.Width, _sizeRequest.Height);
+        });
+    }
+
     public override Color DefaultBackground
     {
         set

src/Avalonia.Controls.WebView/NativeWebView.cs

@@ -694,12 +694,6 @@ protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs chang
             }
         }
 
-        protected override void OnSizeChanged(SizeChangedEventArgs e)
-        {
-            base.OnSizeChanged(e);
-            TryGetAdapter()?.SizeChanged(PixelSize.FromSize(e.NewSize, GetRenderScaling()));
-        }
-
         private void EnsureBackground(IBrush? background)
         {
             if (TryGetAdapter() is { } adapter)

src/Avalonia.Controls.WebView/NativeWebViewControlHost.cs

@@ -23,6 +23,9 @@ internal class NativeWebViewControlHost(WebViewAdapter.NativeHostAdapterFactory
         private TaskCompletionSource<IWebViewAdapter?>? _webViewReadyCompletion;
         private ReparentingScope? _reparentingScope;
         private IPlatformHandle? _defaultChildHandle;
+#if AVALONIA
+        private PixelSize _adapterSize;
+#endif
 
         /// <inheritdoc />
         public event EventHandler<IWebViewAdapter>? AdapterCreated;
@@ -80,6 +83,9 @@ protected override void DestroyNativeControlCore(IPlatformHandle control)
 
             _webViewReadyCompletion?.TrySetCanceled();
             _webViewReadyCompletion = null;
+#if AVALONIA
+            _adapterSize = default;
+#endif
 
             if (adapter is not null)
             {
@@ -109,6 +115,28 @@ private void WebViewAdapterOnInitialized(IWebViewAdapter adapter)
 #endif
         }
 
+#if AVALONIA
+        protected override void OnSizeChanged(SizeChangedEventArgs e)
+        {
+            base.OnSizeChanged(e);
+            UpdateAdapterSize(e.NewSize);
+        }
+
+        // Native control host only moves and resizes the native handle, the adapter needs to be notified separately.
+        private void UpdateAdapterSize(Size size)
+        {
+            if (TryGetAdapter() is not { } adapter || TopLevel.GetTopLevel(this) is not { } topLevel)
+                return;
+
+            var pixelSize = PixelSize.FromSize(size, topLevel.RenderScaling);
+            if (pixelSize.Width <= 0 || pixelSize.Height <= 0 || pixelSize == _adapterSize)
+                return;
+
+            _adapterSize = pixelSize;
+            adapter.SizeChanged(pixelSize);
+        }
+#endif
+
         /// <inheritdoc />
         public IDisposable BeginReparenting(bool yieldOnLayoutBeforeExiting = true)
         {