macOS: raise WebContentProcessTerminated when the web content process dies

src/Avalonia.Controls.WebView.Core/IWebViewAdapter.cs

@@ -385,6 +385,16 @@ internal interface IWebViewAdapterWithInputRedirect : IWebViewAdapter
     event Action<RoutedEventArgs> Input;
 }
 
+internal interface IWebViewAdapterWithProcessTermination : IWebViewAdapter
+{
+    /// <summary>
+    ///     WebContentProcessTerminated dispatches after the web content process backing the webview terminates,
+    ///     for example after a crash or after the operating system reclaims its memory. The native control stays
+    ///     alive but renders nothing until the page is reloaded.
+    /// </summary>
+    event EventHandler? WebContentProcessTerminated;
+}
+
 internal interface IWebViewAdapterWithCommands
 {
     void Copy();

src/Avalonia.Controls.WebView.Core/Macios/Interop/WebKit/WKNavigationDelegate.cs

@@ -14,6 +14,8 @@ internal unsafe class WKNavigationDelegate : NSManagedObjectBase
         s_willPresentNotification = &OnDidFinishNavigation;
     private static readonly delegate* unmanaged[Cdecl]<IntPtr, IntPtr, IntPtr, IntPtr, IntPtr, void>
         s_decidePolicyForNavigationAction = &OnDecidePolicyForNavigationAction;
+    private static readonly delegate* unmanaged[Cdecl]<IntPtr, IntPtr, IntPtr, void>
+        s_webContentProcessDidTerminate = &OnWebContentProcessDidTerminate;
 
     static WKNavigationDelegate()
     {
@@ -31,6 +33,10 @@ static WKNavigationDelegate()
         result = Libobjc.class_addMethod(delegateClass, didReceiveNotificationResponse, s_decidePolicyForNavigationAction, "v@:@@@");
         Debug.Assert(result == 1);
 
+        var webContentProcessDidTerminateSel = Libobjc.sel_getUid("webViewWebContentProcessDidTerminate:");
+        result = Libobjc.class_addMethod(delegateClass, webContentProcessDidTerminateSel, s_webContentProcessDidTerminate, "v@:@");
+        Debug.Assert(result == 1);
+
         result = RegisterManagedMembers(delegateClass) ? 1 : 0;
         Debug.Assert(result == 1);
 
@@ -45,6 +51,7 @@ public WKNavigationDelegate() : base(s_class)
 
     public event EventHandler? DidFinishNavigation;
     public event EventHandler<DecidePolicyNavigationEventArgs>? DecidePolicyNavigation;
+    public event EventHandler? WebContentProcessDidTerminate;
 
     [UnmanagedCallersOnly(CallConvs = [typeof(CallConvCdecl)])]
     private static void OnDidFinishNavigation(IntPtr self, IntPtr sel, IntPtr webView, IntPtr navigation)
@@ -53,6 +60,13 @@ private static void OnDidFinishNavigation(IntPtr self, IntPtr sel, IntPtr webVie
         managed?.DidFinishNavigation?.Invoke(managed, EventArgs.Empty);
     }
 
+    [UnmanagedCallersOnly(CallConvs = [typeof(CallConvCdecl)])]
+    private static void OnWebContentProcessDidTerminate(IntPtr self, IntPtr sel, IntPtr webView)
+    {
+        var managed = ReadManagedSelf<WKNavigationDelegate>(self);
+        managed?.WebContentProcessDidTerminate?.Invoke(managed, EventArgs.Empty);
+    }
+
     private static readonly IntPtr s_actionRequest = Libobjc.sel_getUid("request");
     private static readonly IntPtr s_navigationType = Libobjc.sel_getUid("navigationType");
     private static readonly IntPtr s_targetFrame = Libobjc.sel_getUid("targetFrame");

src/Avalonia.Controls.WebView.Core/Macios/MaciosWebViewAdapter.cs

@@ -18,7 +18,8 @@ namespace Avalonia.Controls.Macios;
 [SupportedOSPlatform("macos")]
 [SupportedOSPlatform("ios")]
 internal class MaciosWebViewAdapter : IWebViewAdapterWithFocus, IWebViewAdapterWithInputRedirect,
-    IWebViewAdapterWithCookieManager, IWebViewAdapterWithCommands, IWebViewWithPrint, IAppleWKWebViewPlatformHandle
+    IWebViewAdapterWithCookieManager, IWebViewAdapterWithCommands, IWebViewAdapterWithProcessTermination,
+    IWebViewWithPrint, IAppleWKWebViewPlatformHandle
 {
     private const string DefaultPostAvWebViewMessageName = "postAvWebViewMessage";
 
@@ -73,6 +74,7 @@ public MaciosWebViewAdapter(AppleWKWebViewEnvironmentRequestedEventArgs options)
         _navDelegate = new WKNavigationDelegate();
         _navDelegate.DidFinishNavigation += OnDelegateOnDidFinishNavigation;
         _navDelegate.DecidePolicyNavigation += OnDelegateOnDecidePolicyNavigation;
+        _navDelegate.WebContentProcessDidTerminate += OnDelegateOnWebContentProcessDidTerminate;
 
         _webView = new WKWebView(_config) { NavigationDelegate = _navDelegate };
         _webView.Opaque = false;
@@ -157,6 +159,7 @@ public Color DefaultBackground
     public event EventHandler<WebResourceRequestedEventArgs>? WebResourceRequested;
     public event EventHandler? GotFocus;
     public event EventHandler<IWebViewAdapterWithFocus.LostFocusDirection>? LostFocus;
+    public event EventHandler? WebContentProcessTerminated;
     public event Action<RoutedEventArgs>? Input;
     public bool GoBack() => _webView.GoBack() != default;
     public bool GoForward() => _webView.GoForward() != default;
@@ -203,6 +206,7 @@ public void Dispose()
         _scriptHandler.DidReceiveScriptMessage -= OnScriptHandlerOnDidReceiveScriptMessage;
         _navDelegate.DidFinishNavigation -= OnDelegateOnDidFinishNavigation;
         _navDelegate.DecidePolicyNavigation -= OnDelegateOnDecidePolicyNavigation;
+        _navDelegate.WebContentProcessDidTerminate -= OnDelegateOnWebContentProcessDidTerminate;
         _webView.PerformKeyEquivalent -= WebViewOnPerformKeyEquivalent;
         _webView.BecomeFirstResponder -= OnWebViewOnBecomeFirstResponder;
         _webView.ResignFirstResponder -= OnWebViewOnResignFirstResponder;
@@ -297,6 +301,11 @@ private async void OnDelegateOnDidFinishNavigation(object? sender, EventArgs arg
         NavigationCompleted?.Invoke(this, new WebViewNavigationCompletedEventArgs { Request = Uri.TryCreate(url!.AbsoluteString, UriKind.Absolute, out var uri) ? uri : null, IsSuccess = true });
     }
 
+    private void OnDelegateOnWebContentProcessDidTerminate(object? sender, EventArgs args)
+    {
+        WebContentProcessTerminated?.Invoke(this, EventArgs.Empty);
+    }
+
     private void OnWebViewOnResignFirstResponder(object? o, EventArgs eventArgs)
     {
         LostFocus?.Invoke(this, IWebViewAdapterWithFocus.LostFocusDirection.Unknown);

src/Avalonia.Controls.WebView/NativeWebDialog.cs

@@ -365,6 +365,17 @@ public bool Move(int x, int y)
         public event EventHandler<Core.WebViewAdapterEventArgs>? AdapterDestroyed;
         public event EventHandler<Core.WebViewEnvironmentRequestedEventArgs>? EnvironmentRequested;
 
+        /// <summary>
+        ///     WebContentProcessTerminated dispatches after the web content process backing the webview terminates,
+        ///     for example after a crash or after the operating system reclaims its memory. The dialog stays open
+        ///     but renders nothing until the page is reloaded, so handle this event to <see cref="Navigate"/> again.
+        /// </summary>
+        /// <remarks>
+        ///     Raised by WebKit-based adapters (WKWebView on macOS and iOS). Other platforms do not raise this
+        ///     event yet.
+        /// </remarks>
+        public event EventHandler? WebContentProcessTerminated;
+
         /// <inheritdoc/>
         public Core.NativeWebViewCommandManager? TryGetCommandManager() => TryGetAdapter() switch
         {
@@ -465,6 +476,8 @@ private void DialogImplOnAdapterDestroyed(object? sender, Core.WebViewAdapterEve
             adapter.WebMessageReceived -= WebViewAdapterOnWebMessageReceived;
             adapter.WebResourceRequested -= WebViewAdapterOnWebResourceRequested;
             adapter.NewWindowRequested -= WebViewAdapterOnNewWindowRequested;
+            if (adapter is Core.IWebViewAdapterWithProcessTermination withProcessTermination)
+                withProcessTermination.WebContentProcessTerminated -= WebViewAdapterOnWebContentProcessTerminated;
             _dialogInitialized = false;
             AdapterDestroyed?.Invoke(this, e);
         }
@@ -492,6 +505,8 @@ private void DialogImplOnAdapterCreated(object? sender, Core.WebViewAdapterEvent
                 adapter.WebResourceRequested += WebViewAdapterOnWebResourceRequested;
             if (_newWindowRequested is not null)
                 adapter.NewWindowRequested += WebViewAdapterOnNewWindowRequested;
+            if (adapter is Core.IWebViewAdapterWithProcessTermination withProcessTermination)
+                withProcessTermination.WebContentProcessTerminated += WebViewAdapterOnWebContentProcessTerminated;
             if (_initialSource is Uri url)
                 adapter.Source = url;
             else if (_initialSource is ValueTuple<string, Uri?> pair)
@@ -528,5 +543,10 @@ private void WebViewAdapterOnNewWindowRequested(object? sender, Core.WebViewNewW
         {
             _newWindowRequested?.Invoke(this, e);
         }
+
+        private void WebViewAdapterOnWebContentProcessTerminated(object? sender, EventArgs e)
+        {
+            WebContentProcessTerminated?.Invoke(this, e);
+        }
     }
 }

src/Avalonia.Controls.WebView/NativeWebView.cs

@@ -247,6 +247,18 @@ public event EventHandler<Core.WebResourceRequestedEventArgs>? WebResourceReques
         /// <inheritdoc/>
         public event EventHandler<Core.WebViewAdapterEventArgs>? AdapterDestroyed;
 
+        /// <summary>
+        ///     WebContentProcessTerminated dispatches after the web content process backing the webview terminates,
+        ///     for example after a crash or after the operating system reclaims its memory. The native control stays
+        ///     alive but renders nothing until the page is reloaded, so handle this event to
+        ///     <see cref="Refresh"/> or <see cref="Navigate"/> again.
+        /// </summary>
+        /// <remarks>
+        ///     Raised by WebKit-based adapters (WKWebView on macOS and iOS). Other platforms do not raise this
+        ///     event yet.
+        /// </remarks>
+        public event EventHandler? WebContentProcessTerminated;
+
         /// <inheritdoc/>
         public Uri Source
         {
@@ -428,6 +440,12 @@ private void WebViewAdapterOnNewWindowRequested(object? sender, Core.WebViewNewW
             _newWindowRequested?.Invoke(this, e);
         }
 
+        private void WebViewAdapterOnWebContentProcessTerminated(object? sender, EventArgs e)
+        {
+            Core.WebViewDispatcher.VerifyAccess();
+            WebContentProcessTerminated?.Invoke(this, e);
+        }
+
 #if AVALONIA
         protected override async void OnAttachedToVisualTree(VisualTreeAttachmentEventArgs e)
         {
@@ -563,6 +581,10 @@ private void ControlHostImplOnAdapterDeinitialized(object? sender, Core.IWebView
             {
                 withInput.Input -= WithInputOnInput;
             }
+            if (adapter is Core.IWebViewAdapterWithProcessTermination withProcessTermination)
+            {
+                withProcessTermination.WebContentProcessTerminated -= WebViewAdapterOnWebContentProcessTerminated;
+            }
 
             AdapterDestroyed?.Invoke(this, new Core.WebViewAdapterEventArgs(adapter));
         }
@@ -595,6 +617,11 @@ private void ControlHostImplOnAdapterCreated(object? sender, Core.IWebViewAdapte
                 withInput.Input += WithInputOnInput;
             }
 
+            if (adapter is Core.IWebViewAdapterWithProcessTermination withProcessTermination)
+            {
+                withProcessTermination.WebContentProcessTerminated += WebViewAdapterOnWebContentProcessTerminated;
+            }
+
             if (_initialSource is Uri url)
             {
                 adapter.Navigate(url);