[webview] Add new method for cross plugin webview access

A new way of supporting cross plugin communication is coming in Flutter 3.44 which allows for access to plugin published values through the `FlutterPluginBinding` on Android and the `FlutterPluginRegistry` on iOS. Update native WebView access to support these new methods and deprecate the old methods.

refs: flutter/flutter#121527 flutter/flutter#182753

# Conflicts:
#	packages/webview_flutter/webview_flutter_wkwebview/pubspec.yaml

Author: fuzzybinary

packages/webview_flutter/webview_flutter_android/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 4.13.0
+
+* Adds new method for accessing native `WebView` from a `FlutterPluginBinding`.
+
 ## 4.12.0
 
 * Adds support for retrieving cookies with `PlatformWebViewCookieManager.getCookies`.

packages/webview_flutter/webview_flutter_android/android/src/main/java/io/flutter/plugins/webviewflutter/WebViewFlutterAndroidExternalApi.java

@@ -8,6 +8,7 @@
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import io.flutter.embedding.engine.FlutterEngine;
+import io.flutter.embedding.engine.plugins.FlutterPlugin;
 
 /**
  * App and package facing native API provided by the `webview_flutter_android` plugin.
@@ -27,13 +28,42 @@ public interface WebViewFlutterAndroidExternalApi {
    * <p>See the Dart method `AndroidWebViewController.webViewIdentifier` to get the identifier of an
    * underlying `WebView`.
    *
+   * @param binding the plugin binding provided by the Flutter engine. If the binding doesn't
+   *     contain an attached instance of {@link WebViewFlutterPlugin}, this method returns null.
+   * @param identifier the associated identifier of the `WebView`.
+   * @return the `WebView` associated with `identifier` or null if a `WebView` instance associated
+   *     with `identifier` could not be found.
+   */
+  @Nullable
+  static WebView getWebView(@NonNull FlutterPlugin.FlutterPluginBinding binding, long identifier) {
+    final WebViewFlutterPlugin webViewPlugin =
+        (WebViewFlutterPlugin) binding.getPlugin(WebViewFlutterPlugin.class);
+
+    if (webViewPlugin != null && webViewPlugin.getInstanceManager() != null) {
+      final Object instance = webViewPlugin.getInstanceManager().getInstance(identifier);
+      if (instance instanceof WebView) {
+        return (WebView) instance;
+      }
+    }
+
+    return null;
+  }
+
+  /**
+   * Retrieves the {@link WebView} that is associated with `identifier`.
+   *
+   * <p>See the Dart method `AndroidWebViewController.webViewIdentifier` to get the identifier of an
+   * underlying `WebView`.
+   *
+   * @deprecated Use {@link #getWebView(FlutterPlugin.FlutterPluginBinding, long)} instead.
    * @param engine the execution environment the {@link WebViewFlutterPlugin} should belong to. If
    *     the engine doesn't contain an attached instance of {@link WebViewFlutterPlugin}, this
    *     method returns null.
    * @param identifier the associated identifier of the `WebView`.
    * @return the `WebView` associated with `identifier` or null if a `WebView` instance associated
    *     with `identifier` could not be found.
    */
+  @Deprecated
   @Nullable
   static WebView getWebView(@NonNull FlutterEngine engine, long identifier) {
     final WebViewFlutterPlugin webViewPlugin =

packages/webview_flutter/webview_flutter_android/android/src/test/java/io/flutter/plugins/webviewflutter/WebViewFlutterAndroidExternalApiTest.java

@@ -6,6 +6,7 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
@@ -33,6 +34,7 @@ public class WebViewFlutterAndroidExternalApiTest {
 
   @Mock FlutterPlugin.FlutterPluginBinding mockPluginBinding;
 
+  @SuppressWarnings("deprecation")
   @Test
   public void getWebView() {
     final WebViewFlutterPlugin webViewFlutterPlugin = new WebViewFlutterPlugin();
@@ -60,4 +62,34 @@ public void getWebView() {
 
     webViewFlutterPlugin.onDetachedFromEngine(mockPluginBinding);
   }
+
+  @Test
+  public void getWebViewFromBinding() {
+    final WebViewFlutterPlugin webViewFlutterPlugin = new WebViewFlutterPlugin();
+
+    when(mockPluginBinding.getApplicationContext()).thenReturn(mockContext);
+    when(mockPluginBinding.getPlatformViewRegistry()).thenReturn(mockViewRegistry);
+    when(mockPluginBinding.getBinaryMessenger()).thenReturn(mockBinaryMessenger);
+
+    webViewFlutterPlugin.onAttachedToEngine(mockPluginBinding);
+
+    final AndroidWebkitLibraryPigeonInstanceManager instanceManager =
+        webViewFlutterPlugin.getInstanceManager();
+    assertNotNull(instanceManager);
+
+    final WebView mockWebView = mock(WebView.class);
+    instanceManager.addDartCreatedInstance(mockWebView, 0);
+
+    when(mockPluginBinding.getPlugin(WebViewFlutterPlugin.class)).thenReturn(webViewFlutterPlugin);
+
+    assertEquals(WebViewFlutterAndroidExternalApi.getWebView(mockPluginBinding, 0), mockWebView);
+
+    webViewFlutterPlugin.onDetachedFromEngine(mockPluginBinding);
+  }
+
+  @Test
+  public void getWebViewFromBindingReturnsNullForUnknownPlugin() {
+    when(mockPluginBinding.getPlugin(WebViewFlutterPlugin.class)).thenReturn(null);
+    assertNull(WebViewFlutterAndroidExternalApi.getWebView(mockPluginBinding, 0));
+  }
 }

packages/webview_flutter/webview_flutter_android/pubspec.yaml

@@ -2,11 +2,11 @@ name: webview_flutter_android
 description: A Flutter plugin that provides a WebView widget on Android.
 repository: https://github.com/flutter/packages/tree/main/packages/webview_flutter/webview_flutter_android
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+webview%22
-version: 4.12.0
+version: 4.13.0
 
 environment:
   sdk: ^3.9.0
-  flutter: ">=3.35.0"
+  flutter: ">=3.44.0"
 
 flutter:
   plugin:

packages/webview_flutter/webview_flutter_wkwebview/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 3.26.0
+
+* Adds new method for accessing native `WKWebViews` from a `FlutterPluginRegistrar`.
+
 ## 3.25.1
 
 * Relands update to prevent message calls when application will terminate.

packages/webview_flutter/webview_flutter_wkwebview/darwin/Tests/FWFWebViewFlutterWKWebViewExternalAPITests.swift

@@ -27,11 +27,11 @@ class FWFWebViewFlutterWKWebViewExternalAPITests: XCTestCase {
 
     WebViewFlutterPlugin.register(with: registrar)
 
-    let plugin = registry.registrar.plugin as! WebViewFlutterPlugin?
+    let plugin = registry.registrar.publishedValue as! WebViewFlutterPlugin
 
     let webView = WKWebView(frame: .zero)
     let webViewIdentifier = 0
-    plugin?.proxyApiRegistrar?.instanceManager.addDartCreatedInstance(
+    plugin.proxyApiRegistrar?.instanceManager.addDartCreatedInstance(
       webView, withIdentifier: Int64(webViewIdentifier))
 
     let result = FWFWebViewFlutterWKWebViewExternalAPI.webView(
@@ -40,26 +40,49 @@ class FWFWebViewFlutterWKWebViewExternalAPITests: XCTestCase {
   }
 
   @MainActor func testWebViewForIdentifierHandlesIncorrectRegistry() {
-    let registry = TestRegistry(publishedValue: false)
+    let registry = TestRegistry()
     // Ensure that passing an empty registry, such as the FlutterAppDelegate
     // in an app that has adopted UIScene, gracefully returns nil.
     let result = FWFWebViewFlutterWKWebViewExternalAPI.webView(
       forIdentifier: 0, withPluginRegistry: registry)
     XCTAssertEqual(result, nil)
   }
-}
 
-class TestRegistry: NSObject, FlutterPluginRegistry {
-  let registrar = TestFlutterPluginRegistrar()
-  let publishedValue: Bool
+  @MainActor func testWebViewForIdentifierFromRegistrar() {
+    let registry = TestRegistry()
+
+    #if os(iOS)
+      let registrar = registry.registrar(forPlugin: "")!
+    #elseif os(macOS)
+      let registrar = registry.registrar(forPlugin: "")
+    #endif
+
+    WebViewFlutterPlugin.register(with: registrar)
+
+    let plugin = registry.registrar.publishedValue as! WebViewFlutterPlugin
+
+    let webView = WKWebView(frame: .zero)
+    let webViewIdentifier = 0
+    plugin.proxyApiRegistrar?.instanceManager.addDartCreatedInstance(
+      webView, withIdentifier: Int64(webViewIdentifier))
 
-  init(publishedValue: Bool) {
-    self.publishedValue = publishedValue
+    let result = FWFWebViewFlutterWKWebViewExternalAPI.webView(
+      forIdentifier: Int64(webViewIdentifier), withPluginRegistrar: registrar)
+    XCTAssertEqual(result, webView)
   }
 
-  convenience override init() {
-    self.init(publishedValue: true)
+  @MainActor func testWebViewForIdentifierHandlesIncorrectRegistrar() {
+    let registrar = TestFlutterPluginRegistrar()
+    // Ensure that passing an empty registry, such as the FlutterAppDelegate
+    // in an app that has adopted UIScene, gracefully returns nil.
+    let result = FWFWebViewFlutterWKWebViewExternalAPI.webView(
+      forIdentifier: 0, withPluginRegistrar: registrar)
+    XCTAssertEqual(result, nil)
   }
+}
+
+class TestRegistry: NSObject, FlutterPluginRegistry {
+  let registrar = TestFlutterPluginRegistrar()
 
   #if os(iOS)
     func registrar(forPlugin pluginKey: String) -> FlutterPluginRegistrar? {
@@ -76,10 +99,7 @@ class TestRegistry: NSObject, FlutterPluginRegistry {
   }
 
   func valuePublished(byPlugin pluginKey: String) -> NSObject? {
-    if publishedValue && pluginKey == "WebViewFlutterPlugin" {
-      return registrar.plugin
-    }
-    return nil
+    return registrar.publishedValue
   }
 }
 
@@ -98,7 +118,7 @@ class TestFlutterTextureRegistry: NSObject, FlutterTextureRegistry {
 }
 
 class TestFlutterPluginRegistrar: NSObject, FlutterPluginRegistrar {
-  var plugin: WebViewFlutterPlugin? = nil
+  var publishedValue: NSObject? = nil
 
   #if os(iOS)
     var viewController: UIViewController?
@@ -144,7 +164,7 @@ class TestFlutterPluginRegistrar: NSObject, FlutterPluginRegistrar {
   }
 
   func publish(_ value: NSObject) {
-    plugin = (value as! WebViewFlutterPlugin)
+    publishedValue = value
   }
 
   func addMethodCallDelegate(_ delegate: FlutterPlugin, channel: FlutterMethodChannel) {
@@ -159,7 +179,10 @@ class TestFlutterPluginRegistrar: NSObject, FlutterPluginRegistrar {
     return ""
   }
 
-  func valuePublished(byPlugin: String) -> NSObject? {
+  func valuePublished(byPlugin pluginKey: String) -> NSObject? {
+    if pluginKey == "WebViewFlutterPlugin" {
+      return publishedValue
+    }
     return nil
   }
 }

packages/webview_flutter/webview_flutter_wkwebview/darwin/webview_flutter_wkwebview/Sources/webview_flutter_wkwebview/WebViewFlutterWKWebViewExternalAPI.swift

@@ -24,6 +24,7 @@ public class FWFWebViewFlutterWKWebViewExternalAPI: NSObject {
   ///
   /// See the Dart method `WebKitWebViewController.webViewIdentifier` to get the identifier of an
   /// underlying `WKWebView`.
+  @available(*, deprecated, message: "Use webView(forIdentifier:withPluginRegistrar:) instead.")
   @objc(webViewForIdentifier:withPluginRegistry:)
   public static func webView(
     forIdentifier identifier: Int64, withPluginRegistry registry: FlutterPluginRegistry
@@ -37,4 +38,22 @@ public class FWFWebViewFlutterWKWebViewExternalAPI: NSObject {
       forIdentifier: identifier)
     return webView
   }
+
+  /// Retrieves the `WKWebView` that is associated with `identifier` using a FlutterPluginRegistrar
+  ///
+  /// See the Dart method `WebKitWebViewController.webViewIdentifier` to get the identifier of an
+  /// underlying `WKWebView`.
+  @objc(webViewForIdentifier:withPluginRegistrar:)
+  public static func webView(
+    forIdentifier identifier: Int64, withPluginRegistrar registrar: FlutterPluginRegistrar
+  ) -> WKWebView? {
+    let plugin = registrar.valuePublished(byPlugin: "WebViewFlutterPlugin")
+    guard let webviewPlugin = plugin as? WebViewFlutterPlugin else {
+      return nil
+    }
+
+    let webView: WKWebView? = webviewPlugin.proxyApiRegistrar?.instanceManager.instance(
+      forIdentifier: identifier)
+    return webView
+  }
 }

packages/webview_flutter/webview_flutter_wkwebview/pubspec.yaml

@@ -2,11 +2,11 @@ name: webview_flutter_wkwebview
 description: A Flutter plugin that provides a WebView widget based on Apple's WKWebView control.
 repository: https://github.com/flutter/packages/tree/main/packages/webview_flutter/webview_flutter_wkwebview
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+webview%22
-version: 3.25.1
+version: 3.26.0
 
 environment:
-  sdk: ^3.10.0
-  flutter: ">=3.38.0"
+  sdk: ^3.9.0
+  flutter: ">=3.44.0"
 
 flutter:
   plugin: