Add plugin shim to facilitate old plugins in new embedding (#33478).

ci/licenses_golden/licenses_flutter

@@ -532,6 +532,8 @@ FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/plugin
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/plugins/service/ServiceAware.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/plugins/service/ServiceControlSurface.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/plugins/service/ServicePluginBinding.java
+FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/plugins/shim/ShimPluginRegistry.java
+FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/plugins/shim/ShimRegistrar.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/renderer/FlutterRenderer.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/renderer/OnFirstFrameRenderedListener.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/engine/systemchannels/AccessibilityChannel.java

shell/platform/android/BUILD.gn

@@ -149,6 +149,8 @@ action("flutter_shell_java") {
     "io/flutter/embedding/engine/plugins/service/ServiceAware.java",
     "io/flutter/embedding/engine/plugins/service/ServiceControlSurface.java",
     "io/flutter/embedding/engine/plugins/service/ServicePluginBinding.java",
+    "io/flutter/embedding/engine/plugins/shim/ShimPluginRegistry.java",
+    "io/flutter/embedding/engine/plugins/shim/ShimRegistrar.java",
     "io/flutter/embedding/engine/renderer/FlutterRenderer.java",
     "io/flutter/embedding/engine/renderer/OnFirstFrameRenderedListener.java",
     "io/flutter/embedding/engine/systemchannels/AccessibilityChannel.java",

shell/platform/android/io/flutter/embedding/android/FlutterActivity.java

@@ -151,7 +151,7 @@ public Intent build(@NonNull Context context) {
   }
 
   @Override
-  public void onCreate(Bundle savedInstanceState) {
+  protected void onCreate(Bundle savedInstanceState) {
     Log.d(TAG, "onCreate()");
     super.onCreate(savedInstanceState);
     setContentView(createFragmentContainer());

shell/platform/android/io/flutter/embedding/engine/FlutterEngine.java

@@ -9,6 +9,9 @@
 import android.content.Context;
 import android.support.annotation.NonNull;
 
+import java.util.HashSet;
+import java.util.Set;
+
 import io.flutter.embedding.engine.dart.DartExecutor;
 import io.flutter.embedding.engine.plugins.PluginRegistry;
 import io.flutter.embedding.engine.plugins.activity.ActivityControlSurface;
@@ -84,11 +87,13 @@ public class FlutterEngine implements LifecycleOwner {
   @NonNull
   private final TextInputChannel textInputChannel;
 
+  private final Set<EngineLifecycleListener> engineLifecycleListeners = new HashSet<>();
   private final EngineLifecycleListener engineLifecycleListener = new EngineLifecycleListener() {
     @SuppressWarnings("unused")
     public void onPreEngineRestart() {
-      // TODO(mattcarroll): work into plugin API. should probably loop through each plugin.
-//      pluginRegistry.onPreEngineRestart();
+      for (EngineLifecycleListener lifecycleListener : engineLifecycleListeners) {
+        lifecycleListener.onPreEngineRestart();
+      }
     }
   };
 
@@ -165,6 +170,22 @@ public void destroy() {
     flutterJNI.detachFromNativeAndReleaseResources();
   }
 
+  /**
+   * Adds a {@code listener} to be notified of Flutter engine lifecycle events, e.g.,
+   * {@code onPreEngineStart()}.
+   */
+  public void addEngineLifecycleListener(@NonNull EngineLifecycleListener listener) {
+    engineLifecycleListeners.add(listener);
+  }
+
+  /**
+   * Removes a {@code listener} that was previously added with
+   * {@link #addEngineLifecycleListener(EngineLifecycleListener)}.
+   */
+  public void removeEngineLifecycleListener(@NonNull EngineLifecycleListener listener) {
+    engineLifecycleListeners.remove(listener);
+  }
+
   /**
    * The Dart execution context associated with this {@code FlutterEngine}.
    *

shell/platform/android/io/flutter/embedding/engine/plugins/shim/ShimPluginRegistry.java

@@ -0,0 +1,92 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package io.flutter.embedding.engine.plugins.shim;
+
+import android.app.Activity;
+import android.support.annotation.NonNull;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import io.flutter.embedding.engine.FlutterEngine;
+import io.flutter.plugin.common.PluginRegistry;
+import io.flutter.plugin.platform.PlatformViewsController;
+import io.flutter.view.FlutterView;
+
+/**
+ * A {@link PluginRegistry} that is shimmed to use the new Android embedding and plugin API behind
+ * the scenes.
+ * <p>
+ * The following is an example usage of {@code ShimPluginRegistry} within a {@code FlutterActivity}:
+ * {@code
+ *   // Create the FlutterEngine that will back the Flutter UI.
+ *   FlutterEngine flutterEngine = new FlutterEngine(context);
+ *
+ *   // Create a ShimPluginRegistry and wrap the FlutterEngine with the shim.
+ *   ShimPluginRegistry shimPluginRegistry = new ShimPluginRegistry(flutterEngine, platformViewsController);
+ *
+ *   // Use the GeneratedPluginRegistrant to add every plugin that's in the pubspec.
+ *   GeneratedPluginRegistrant.registerWith(shimPluginRegistry);
+ * }
+ */
+public class ShimPluginRegistry implements PluginRegistry {
+  private final FlutterEngine flutterEngine;
+  private final PlatformViewsController platformViewsController;
+  private final Map<String, Object> pluginMap = new HashMap<>();
+  private final FlutterEngine.EngineLifecycleListener engineLifecycleListener = new FlutterEngine.EngineLifecycleListener() {
+    @Override
+    public void onPreEngineRestart() {
+      ShimPluginRegistry.this.onPreEngineRestart();
+    }
+  };
+
+  public ShimPluginRegistry(
+      @NonNull FlutterEngine flutterEngine,
+      @NonNull PlatformViewsController platformViewsController
+  ) {
+    this.flutterEngine = flutterEngine;
+    this.flutterEngine.addEngineLifecycleListener(engineLifecycleListener);
+    this.platformViewsController = platformViewsController;
+  }
+
+  @Override
+  public Registrar registrarFor(String pluginKey) {
+    if (pluginMap.containsKey(pluginKey)) {
+      throw new IllegalStateException("Plugin key " + pluginKey + " is already in use");
+    }
+    pluginMap.put(pluginKey, null);
+    ShimRegistrar registrar = new ShimRegistrar(pluginKey, pluginMap);
+    flutterEngine.getPlugins().add(registrar);
+    return registrar;
+  }
+
+  @Override
+  public boolean hasPlugin(String pluginKey) {
+    return pluginMap.containsKey(pluginKey);
+  }
+
+  @Override
+  public <T> T valuePublishedByPlugin(String pluginKey) {
+    return (T) pluginMap.get(pluginKey);
+  }
+
+  //----- From FlutterPluginRegistry that aren't in the PluginRegistry interface ----//
+  public void attach(FlutterView flutterView, Activity activity) {
+    platformViewsController.attach(activity, flutterEngine.getRenderer(), flutterEngine.getDartExecutor());
+  }
+
+  public void detach() {
+    platformViewsController.detach();
+    platformViewsController.onFlutterViewDestroyed();
+  }
+
+  private void onPreEngineRestart() {
+    platformViewsController.onPreEngineRestart();
+  }
+
+  public PlatformViewsController getPlatformViewsController() {
+    return platformViewsController;
+  }
+}

shell/platform/android/io/flutter/embedding/engine/plugins/shim/ShimRegistrar.java

@@ -0,0 +1,203 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package io.flutter.embedding.engine.plugins.shim;
+
+import android.app.Activity;
+import android.content.Context;
+import android.support.annotation.NonNull;
+
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+import io.flutter.embedding.engine.plugins.FlutterPlugin;
+import io.flutter.embedding.engine.plugins.activity.ActivityAware;
+import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding;
+import io.flutter.plugin.common.BinaryMessenger;
+import io.flutter.plugin.common.PluginRegistry;
+import io.flutter.plugin.platform.PlatformViewRegistry;
+import io.flutter.view.FlutterMain;
+import io.flutter.view.FlutterView;
+import io.flutter.view.TextureRegistry;
+
+/**
+ * A {@link PluginRegistry.Registrar} that is shimmed to use the new Android embedding and plugin
+ * API behind the scenes.
+ * <p>
+ * Instances of {@code ShimRegistrar}s are vended internally by a {@link ShimPluginRegistry}.
+ */
+class ShimRegistrar implements PluginRegistry.Registrar, FlutterPlugin, ActivityAware {
+  private static final String TAG = "ShimRegistrar";
+
+  private final Map<String, Object> globalRegistrarMap;
+  private final String pluginId;
+  private final Set<PluginRegistry.ViewDestroyListener> viewDestroyListeners = new HashSet<>();
+  private final Set<PluginRegistry.RequestPermissionsResultListener> requestPermissionsResultListeners = new HashSet<>();
+  private final Set<PluginRegistry.ActivityResultListener> activityResultListeners = new HashSet<>();
+  private final Set<PluginRegistry.NewIntentListener> newIntentListeners = new HashSet<>();
+  private final Set<PluginRegistry.UserLeaveHintListener> userLeaveHintListeners = new HashSet<>();
+  private FlutterPlugin.FlutterPluginBinding pluginBinding;
+  private ActivityPluginBinding activityPluginBinding;
+
+  public ShimRegistrar(@NonNull String pluginId, @NonNull Map<String, Object> globalRegistrarMap) {
+    this.pluginId = pluginId;
+    this.globalRegistrarMap = globalRegistrarMap;
+  }
+
+  @Override
+  public Activity activity() {
+    return activityPluginBinding != null ? activityPluginBinding.getActivity() : null;
+  }
+
+  @Override
+  public Context context() {
+    return pluginBinding != null ? pluginBinding.getApplicationContext() : null;
+  }
+
+  @Override
+  public Context activeContext() {
+    return activityPluginBinding == null ? context() : activity();
+  }
+
+  @Override
+  public BinaryMessenger messenger() {
+    return pluginBinding != null ? pluginBinding.getFlutterEngine().getDartExecutor() : null;
+  }
+
+  @Override
+  public TextureRegistry textures() {
+    return pluginBinding != null ? pluginBinding.getFlutterEngine().getRenderer() : null;
+  }
+
+  @Override
+  public PlatformViewRegistry platformViewRegistry() {
+    return null;
+  }
+
+  @Override
+  public FlutterView view() {
+    throw new UnsupportedOperationException("The new embedding does not support the old FlutterView.");
+  }
+
+  @Override
+  public String lookupKeyForAsset(String asset) {
+    return FlutterMain.getLookupKeyForAsset(asset);
+  }
+
+  @Override
+  public String lookupKeyForAsset(String asset, String packageName) {
+    return FlutterMain.getLookupKeyForAsset(asset, packageName);
+  }
+
+  @Override
+  public PluginRegistry.Registrar publish(Object value) {
+    globalRegistrarMap.put(pluginId, value);
+    return this;
+  }
+
+  @Override
+  public PluginRegistry.Registrar addRequestPermissionsResultListener(PluginRegistry.RequestPermissionsResultListener listener) {
+    requestPermissionsResultListeners.add(listener);
+
+    if (activityPluginBinding != null) {
+      activityPluginBinding.addRequestPermissionsResultListener(listener);
+    }
+
+    return this;
+  }
+
+  @Override
+  public PluginRegistry.Registrar addActivityResultListener(PluginRegistry.ActivityResultListener listener) {
+    activityResultListeners.add(listener);
+
+    if (activityPluginBinding != null) {
+      activityPluginBinding.addActivityResultListener(listener);
+    }
+
+    return this;
+  }
+
+  @Override
+  public PluginRegistry.Registrar addNewIntentListener(PluginRegistry.NewIntentListener listener) {
+    newIntentListeners.add(listener);
+
+    if (activityPluginBinding != null) {
+      activityPluginBinding.addOnNewIntentListener(listener);
+    }
+
+    return this;
+  }
+
+  @Override
+  public PluginRegistry.Registrar addUserLeaveHintListener(PluginRegistry.UserLeaveHintListener listener) {
+    userLeaveHintListeners.add(listener);
+
+    if (activityPluginBinding != null) {
+      activityPluginBinding.addOnUserLeaveHintListener(listener);
+    }
+
+    return this;
+  }
+
+  @Override
+  @NonNull
+  public PluginRegistry.Registrar addViewDestroyListener(@NonNull PluginRegistry.ViewDestroyListener listener) {
+    viewDestroyListeners.add(listener);
+    return this;
+  }
+
+  @Override
+  public void onAttachedToEngine(@NonNull FlutterPluginBinding binding) {
+    pluginBinding = binding;
+  }
+
+  @Override
+  public void onDetachedFromEngine(@NonNull FlutterPluginBinding binding) {
+    for (PluginRegistry.ViewDestroyListener listener : viewDestroyListeners) {
+      // The following invocation might produce unexpected behavior in old plugins because
+      // we have no FlutterNativeView to pass to onViewDestroy(). This is a limitation of this shim.
+      listener.onViewDestroy(null);
+    }
+
+    pluginBinding = null;
+  }
+
+  @Override
+  public void onAttachedToActivity(@NonNull ActivityPluginBinding binding) {
+    activityPluginBinding = binding;
+    addExistingListenersToActivityPluginBinding();
+  }
+
+  @Override
+  public void onDetachedFromActivityForConfigChanges() {
+    activityPluginBinding = null;
+  }
+
+  @Override
+  public void onReattachedToActivityForConfigChanges(@NonNull ActivityPluginBinding binding) {
+    activityPluginBinding = binding;
+    addExistingListenersToActivityPluginBinding();
+  }
+
+  @Override
+  public void onDetachedFromActivity() {
+    activityPluginBinding = null;
+  }
+
+  private void addExistingListenersToActivityPluginBinding() {
+    for (PluginRegistry.RequestPermissionsResultListener listener : requestPermissionsResultListeners) {
+      activityPluginBinding.addRequestPermissionsResultListener(listener);
+    }
+    for (PluginRegistry.ActivityResultListener listener : activityResultListeners) {
+      activityPluginBinding.addActivityResultListener(listener);
+    }
+    for (PluginRegistry.NewIntentListener listener : newIntentListeners) {
+      activityPluginBinding.addOnNewIntentListener(listener);
+    }
+    for (PluginRegistry.UserLeaveHintListener listener : userLeaveHintListeners) {
+      activityPluginBinding.addOnUserLeaveHintListener(listener);
+    }
+  }
+}