OnExternalNavigationStarting

Microsoft.Maui.sln

@@ -200,7 +200,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "MauiBlazorWebView.DeviceTes
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "SharedSource", "SharedSource", "{4F2926C8-43AB-4328-A735-D9EAD699F81D}"
 	ProjectSection(SolutionItems) = preProject
-		src\BlazorWebView\src\SharedSource\ExternalLinkMode.cs = src\BlazorWebView\src\SharedSource\ExternalLinkMode.cs
+		src\BlazorWebView\src\SharedSource\ExternalLinkNavigationInfo.cs = src\BlazorWebView\src\SharedSource\ExternalLinkNavigationInfo.cs
+		src\BlazorWebView\src\SharedSource\ExternalLinkNavigationPolicy.cs = src\BlazorWebView\src\SharedSource\ExternalLinkNavigationPolicy.cs
 		src\BlazorWebView\src\SharedSource\QueryStringHelper.cs = src\BlazorWebView\src\SharedSource\QueryStringHelper.cs
 		src\BlazorWebView\src\SharedSource\WebView2WebViewManager.cs = src\BlazorWebView\src\SharedSource\WebView2WebViewManager.cs
 	EndProjectSection

src/BlazorWebView/src/Maui/Android/WebKitWebViewClient.cs

@@ -33,10 +33,8 @@ public override bool ShouldOverrideUrlLoading(AWebView? view, IWebResourceReques
 			// Handle redirects to the app custom scheme by reloading the URL in the view.
 			// Handle navigation to external URLs using the system browser, unless overriden.
 			var requestUri = request?.Url?.ToString();
-			if (requestUri != null)
+			if (Uri.TryCreate(requestUri, UriKind.RelativeOrAbsolute, out var uri))
 			{
-				var uri = new Uri(requestUri);
-
 				if (uri.Host == BlazorWebView.AppHostAddress &&
 					view is not null && 
 					request is not null && 
@@ -46,13 +44,21 @@ request is not null &&
 					view.LoadUrl(uri.ToString());
 					return true;
 				}
-				else if (uri.Host != BlazorWebView.AppHostAddress && 
-					_webViewHandler != null &&
-					_webViewHandler.ExternalLinkMode == ExternalLinkMode.OpenInExternalBrowser)
+				else if (uri.Host != BlazorWebView.AppHostAddress && _webViewHandler != null)
 				{
-					var intent = new Intent(Intent.ActionView, AUri.Parse(requestUri));
-					_webViewHandler.Context.StartActivity(intent);
-					return true;
+					var callbackArgs = new ExternalLinkNavigationInfo(uri);
+					var externalLinkMode = _webViewHandler.OnExternalNavigationStarting?.Invoke(callbackArgs) ?? ExternalLinkNavigationPolicy.OpenInExternalBrowser;
+
+					if (externalLinkMode == ExternalLinkNavigationPolicy.OpenInExternalBrowser)
+					{
+						var intent = new Intent(Intent.ActionView, AUri.Parse(requestUri));
+						_webViewHandler.Context.StartActivity(intent);
+					}
+
+					if (externalLinkMode != ExternalLinkNavigationPolicy.OpenInWebView)
+					{
+						return true;
+					}
 				}
 			}
 

src/BlazorWebView/src/Maui/BlazorWebView.cs

@@ -1,4 +1,5 @@
-using Microsoft.AspNetCore.Components.Web;
+using System;
+using Microsoft.AspNetCore.Components.Web;
 using Microsoft.AspNetCore.Components.WebView;
 using Microsoft.Extensions.FileProviders;
 
@@ -21,12 +22,8 @@ public BlazorWebView()
 
 		public RootComponentsCollection RootComponents { get; }
 
-		/// <summary>
-		/// Specify whether links should be opened in the external
-		/// system default browser, or within the webview.
-		/// </summary>
-		/// <value>Defaults to opening links in the system default browser.</value>
-		public ExternalLinkMode ExternalLinkMode { get; set; } = ExternalLinkMode.OpenInExternalBrowser;
+		/// <inheritdoc/>
+		public Func<ExternalLinkNavigationInfo, ExternalLinkNavigationPolicy>? OnExternalNavigationStarting { get; set; } 
 
 		/// <inheritdoc/>
 		public virtual IFileProvider CreateFileProvider(string contentRootDir)

src/BlazorWebView/src/Maui/BlazorWebViewHandler.cs

@@ -1,4 +1,5 @@
-using System.Linq;
+using System;
+using System.Linq;
 using Microsoft.AspNetCore.Components.WebView;
 using Microsoft.Maui;
 using Microsoft.Maui.Handlers;
@@ -11,7 +12,7 @@ public partial class BlazorWebViewHandler
 		{
 			[nameof(IBlazorWebView.HostPage)] = MapHostPage,
 			[nameof(IBlazorWebView.RootComponents)] = MapRootComponents,
-			[nameof(IBlazorWebView.ExternalLinkMode)] = MapExternalLinkMode,
+			[nameof(IBlazorWebView.OnExternalNavigationStarting)] = MapOnExternalNavigationStarting,
 		};
 
 		public BlazorWebViewHandler() : base(BlazorWebViewMapper)
@@ -42,17 +43,17 @@ public static void MapRootComponents(BlazorWebViewHandler handler, IBlazorWebVie
 #endif
 		}
 
-		public static void MapExternalLinkMode(BlazorWebViewHandler handler, IBlazorWebView webView)
+		public static void MapOnExternalNavigationStarting(BlazorWebViewHandler handler, IBlazorWebView webView)
 		{
 #if !NETSTANDARD
-			handler.ExternalLinkMode = webView.ExternalLinkMode;
+			handler.OnExternalNavigationStarting = webView.OnExternalNavigationStarting;
 			handler.StartWebViewCoreIfPossible();
 #endif
 		}
 
 #if !NETSTANDARD
 		private string? HostPage { get; set; }
-		internal ExternalLinkMode ExternalLinkMode { get; private set; }
+		internal Func<ExternalLinkNavigationInfo, ExternalLinkNavigationPolicy>? OnExternalNavigationStarting { get; private set; }
 
 		private RootComponentsCollection? _rootComponents;
 		private RootComponentsCollection? RootComponents

src/BlazorWebView/src/Maui/IBlazorWebView.cs

@@ -1,4 +1,5 @@
-using Microsoft.AspNetCore.Components.Web;
+using System;
+using Microsoft.AspNetCore.Components.Web;
 using Microsoft.AspNetCore.Components.WebView;
 using Microsoft.Extensions.FileProviders;
 using Microsoft.Maui;
@@ -12,10 +13,10 @@ public interface IBlazorWebView : IView
 		JSComponentConfigurationStore JSComponents { get; }
 
 		/// <summary>
-		/// Specify whether links should be opened in the external
-		/// system default browser, or within the webview.
+		/// Allows customizing how external links are opened.
+		/// Opens external links in the system browser by default.
 		/// </summary>
-		ExternalLinkMode ExternalLinkMode { get; set; }
+		Func<ExternalLinkNavigationInfo, ExternalLinkNavigationPolicy>? OnExternalNavigationStarting { get; set; }
 
 		/// <summary>
 		/// Creates a file provider for static assets used in the <see cref="BlazorWebView"/>. The default implementation

src/BlazorWebView/src/Maui/Windows/WinUIWebViewManager.cs

@@ -105,19 +105,27 @@ protected override async Task HandleWebResourceRequest(CoreWebView2WebResourceRe
 
 		protected override void CoreWebView2_NavigationStarting(object sender, CoreWebView2NavigationStartingEventArgs args)
 		{
-			if (Uri.TryCreate(args.Uri, UriKind.RelativeOrAbsolute, out var uri) &&
-				uri.Host != AppHostAddress &&
-				_blazorWebViewHandler.ExternalLinkMode == ExternalLinkMode.OpenInExternalBrowser)
+			if (Uri.TryCreate(args.Uri, UriKind.RelativeOrAbsolute, out var uri) && uri.Host != AppHostAddress)
 			{
-				_ = Launcher.LaunchUriAsync(uri);
-				args.Cancel = true;
+				var callbackArgs = new ExternalLinkNavigationInfo(uri);
+				var externalLinkMode = _blazorWebViewHandler.OnExternalNavigationStarting?.Invoke(callbackArgs) ?? ExternalLinkNavigationPolicy.OpenInExternalBrowser;
+
+				if (externalLinkMode == ExternalLinkNavigationPolicy.OpenInExternalBrowser)
+				{
+					_ = Launcher.LaunchUriAsync(uri);
+				}
+
+				if (externalLinkMode != ExternalLinkNavigationPolicy.OpenInWebView)
+				{
+					args.Cancel = true;
+				}
 			}
 		}
 
 		protected override void CoreWebView2_NewWindowRequested(object sender, CoreWebView2NewWindowRequestedEventArgs args)
 		{
-			// Intercept _blank target <a> tags to always open in device browser
-			// regardless of ExternalLinkMode.OpenInWebview
+			// Intercept _blank target <a> tags to always open in device browser.
+			// The ExternalLinkCallback is not invoked.
 			if (Uri.TryCreate(args.Uri, UriKind.RelativeOrAbsolute, out var uri))
 			{
 				_ = Launcher.LaunchUriAsync(uri);

src/BlazorWebView/src/SharedSource/ExternalLinkNavigationInfo.cs

@@ -0,0 +1,23 @@
+using System;
+
+namespace Microsoft.AspNetCore.Components.WebView
+{
+	/// <summary>
+	/// Used to provide information about a link (<![CDATA[<a>]]>) clicked within a Blazor WebView.
+	/// 
+	/// `_blank` target links will always open in the default browser
+	/// thus the OnExternalNavigationStarting won't be called.
+	/// </summary>
+	public class ExternalLinkNavigationInfo
+	{
+		public ExternalLinkNavigationInfo(Uri uri)
+		{
+			Uri = uri;
+		}
+
+		/// <summary>
+		/// External <see cref="Uri">Uri</see> to be navigated to.
+		/// </summary>
+		public Uri Uri { get; set; }
+	}
+}

src/BlazorWebView/src/SharedSource/ExternalLinkMode.cs → src/BlazorWebView/src/SharedSource/ExternalLinkNavigationPolicy.cs

@@ -1,12 +1,12 @@
 namespace Microsoft.AspNetCore.Components.WebView
 {
 	/// <summary>
-	/// Link handling mode for anchor tags <![CDATA[<a>]]> within a Blazor WebView.
+	/// Link handling policy for anchor tags <![CDATA[<a>]]> within a Blazor WebView.
 	/// 
 	/// `_blank` target links will always open in the default browser
-	/// regardless of this setting.
+	/// regardless of the policy.
 	/// </summary>
-	public enum ExternalLinkMode
+	public enum ExternalLinkNavigationPolicy
 	{
 		/// <summary>
 		/// Opens anchor tags <![CDATA[<a>]]> in the system default browser.
@@ -16,6 +16,11 @@ public enum ExternalLinkMode
 		/// <summary>
 		/// Opens anchor tags <![CDATA[<a>]]> in the WebView. This is not recommended.
 		/// </summary>
-		OpenInWebView
+		OpenInWebView,
+
+		/// <summary>
+		/// Cancels the current navigation attempt to an external link.
+		/// </summary>
+		CancelNavigation
 	}
 }