Android embedding API updates for plugin ecosystem - plugin facade, s…

…plit Lifecycle, save state callbacks to plugins (#43241, #43242, #43295) (#13280)

shell/platform/android/BUILD.gn

@@ -416,6 +416,7 @@ action("robolectric_tests") {
     "test/io/flutter/SmokeTest.java",
     "test/io/flutter/embedding/android/FlutterActivityAndFragmentDelegateTest.java",
     "test/io/flutter/embedding/android/FlutterActivityTest.java",
+    "test/io/flutter/embedding/android/FlutterAndroidComponentTest.java",
     "test/io/flutter/embedding/android/FlutterFragmentTest.java",
     "test/io/flutter/embedding/android/FlutterViewTest.java",
     "test/io/flutter/embedding/engine/FlutterEngineCacheTest.java",

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

@@ -399,6 +399,7 @@ protected void onCreate(@Nullable Bundle savedInstanceState) {
 
     delegate = new FlutterActivityAndFragmentDelegate(this);
     delegate.onAttach(this);
+    delegate.onActivityCreated(savedInstanceState);
 
     configureWindowForTransparency();
     setContentView(createFlutterView());
@@ -557,6 +558,12 @@ protected void onStop() {
     lifecycle.handleLifecycleEvent(Lifecycle.Event.ON_STOP);
   }
 
+  @Override
+  protected void onSaveInstanceState(Bundle outState) {
+    super.onSaveInstanceState(outState);
+    delegate.onSaveInstanceState(outState);
+  }
+
   @Override
   protected void onDestroy() {
     super.onDestroy();

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

@@ -142,8 +142,6 @@ FlutterEngine getFlutterEngine() {
   void onAttach(@NonNull Context context) {
     ensureAlive();
 
-    initializeFlutter(context);
-
     // When "retain instance" is true, the FlutterEngine will survive configuration
     // changes. Therefore, we create a new one only if one does not already exist.
     if (flutterEngine == null) {
@@ -178,13 +176,6 @@ void onAttach(@NonNull Context context) {
     host.configureFlutterEngine(flutterEngine);
   }
 
-  private void initializeFlutter(@NonNull Context context) {
-    FlutterMain.ensureInitializationComplete(
-        context.getApplicationContext(),
-        host.getFlutterShellArgs().toArray()
-    );
-  }
-
   /**
    * Obtains a reference to a FlutterEngine to back this delegate and its {@code host}.
    * <p>
@@ -223,7 +214,7 @@ private void setupFlutterEngine() {
     // FlutterView.
     Log.d(TAG, "No preferred FlutterEngine was provided. Creating a new FlutterEngine for"
         + " this FlutterFragment.");
-    flutterEngine = new FlutterEngine(host.getContext());
+    flutterEngine = new FlutterEngine(host.getContext(), host.getFlutterShellArgs().toArray());
     isFlutterEngineFromHost = false;
   }
 
@@ -257,6 +248,15 @@ View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nulla
     return flutterSplashView;
   }
 
+  void onActivityCreated(@Nullable Bundle bundle) {
+    Log.v(TAG, "onActivityCreated. Giving plugins an opportunity to restore state.");
+    ensureAlive();
+
+    if (host.shouldAttachEngineToActivity()) {
+      flutterEngine.getActivityControlSurface().onRestoreInstanceState(bundle);
+    }
+  }
+
   /**
    * Invoke this from {@code Activity#onStart()} or {@code Fragment#onStart()}.
    * <p>
@@ -404,6 +404,15 @@ void onDestroyView() {
     flutterView.removeOnFirstFrameRenderedListener(flutterUiDisplayListener);
   }
 
+  void onSaveInstanceState(@Nullable Bundle bundle) {
+    Log.v(TAG, "onSaveInstanceState. Giving plugins an opportunity to save state.");
+    ensureAlive();
+
+    if (host.shouldAttachEngineToActivity()) {
+      flutterEngine.getActivityControlSurface().onSaveInstanceState(bundle);
+    }
+  }
+
   /**
    * Invoke this from {@code Activity#onDestroy()} or {@code Fragment#onDetach()}.
    * <p>

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

@@ -586,6 +586,12 @@ public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container,
     return delegate.onCreateView(inflater, container, savedInstanceState);
   }
 
+  @Override
+  public void onActivityCreated(@Nullable Bundle savedInstanceState) {
+    super.onActivityCreated(savedInstanceState);
+    delegate.onActivityCreated(savedInstanceState);
+  }
+
   @Override
   public void onStart() {
     super.onStart();
@@ -622,6 +628,12 @@ public void onDestroyView() {
     delegate.onDestroyView();
   }
 
+  @Override
+  public void onSaveInstanceState(Bundle outState) {
+    super.onSaveInstanceState(outState);
+    delegate.onSaveInstanceState(outState);
+  }
+
   @Override
   public void onDetach() {
     super.onDetach();

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

@@ -8,6 +8,7 @@
 import android.arch.lifecycle.LifecycleOwner;
 import android.content.Context;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 
 import java.util.HashSet;
 import java.util.Set;
@@ -143,18 +144,45 @@ public void onPreEngineRestart() {
    * and {@link FlutterLoader#ensureInitializationComplete(Context, String[])}.
    */
   public FlutterEngine(@NonNull Context context) {
-    this(context, FlutterLoader.getInstance(), new FlutterJNI());
+    this(context, null);
+  }
+
+  /**
+   * Same as {@link #FlutterEngine(Context)} with added support for passing Dart
+   * VM arguments.
+   * <p>
+   * If the Dart VM has already started, the given arguments will have no effect.
+   */
+  public FlutterEngine(@NonNull Context context, @Nullable String[] dartVmArgs) {
+    this(context, FlutterLoader.getInstance(), new FlutterJNI(), dartVmArgs);
+  }
+
+  /**
+   * Same as {@link #FlutterEngine(Context, FlutterLoader, FlutterJNI, String[])} but with no Dart
+   * VM flags.
+   */
+  public FlutterEngine(
+      @NonNull Context context,
+      @NonNull FlutterLoader flutterLoader,
+      @NonNull FlutterJNI flutterJNI
+  ) {
+    this(context, flutterLoader, flutterJNI, null);
   }
 
   /**
    * Constructs a new {@code FlutterEngine}. See {@link #FlutterEngine(Context)}.
    *
    * {@code flutterJNI} should be a new instance that has never been attached to an engine before.
    */
-  public FlutterEngine(@NonNull Context context, @NonNull FlutterLoader flutterLoader, @NonNull FlutterJNI flutterJNI) {
+  public FlutterEngine(
+      @NonNull Context context,
+      @NonNull FlutterLoader flutterLoader,
+      @NonNull FlutterJNI flutterJNI,
+      @Nullable String[] dartVmArgs
+  ) {
     this.flutterJNI = flutterJNI;
     flutterLoader.startInitialization(context);
-    flutterLoader.ensureInitializationComplete(context, null);
+    flutterLoader.ensureInitializationComplete(context, dartVmArgs);
 
     flutterJNI.addEngineLifecycleListener(engineLifecycleListener);
     attachToJni();

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

@@ -11,6 +11,7 @@
 import android.content.ContentProvider;
 import android.content.Context;
 import android.content.Intent;
+import android.os.Bundle;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 
@@ -49,6 +50,8 @@ class FlutterEnginePluginRegistry implements PluginRegistry,
 
   // Standard FlutterPlugin
   @NonNull
+  private final FlutterEngine flutterEngine;
+  @NonNull
   private final FlutterPlugin.FlutterPluginBinding pluginBinding;
   @NonNull
   private final FlutterEngineAndroidLifecycle flutterEngineAndroidLifecycle;
@@ -91,10 +94,14 @@ class FlutterEnginePluginRegistry implements PluginRegistry,
       @NonNull FlutterEngine flutterEngine,
       @NonNull FlutterEngineAndroidLifecycle lifecycle
   ) {
+    this.flutterEngine = flutterEngine;
     flutterEngineAndroidLifecycle = lifecycle;
     pluginBinding = new FlutterPlugin.FlutterPluginBinding(
         appContext,
         flutterEngine,
+        flutterEngine.getDartExecutor(),
+        flutterEngine.getRenderer(),
+        flutterEngine.getPlatformViewsController().getRegistry(),
         lifecycle
     );
   }
@@ -288,16 +295,16 @@ public void attachToActivity(
     detachFromAndroidComponent();
 
     this.activity = activity;
-    this.activityPluginBinding = new FlutterEngineActivityPluginBinding(activity);
+    this.activityPluginBinding = new FlutterEngineActivityPluginBinding(activity, lifecycle);
     this.flutterEngineAndroidLifecycle.setBackingLifecycle(lifecycle);
 
     // Activate the PlatformViewsController. This must happen before any plugins attempt
     // to use it, otherwise an error stack trace will appear that says there is no
     // flutter/platform_views channel.
-    pluginBinding.getFlutterEngine().getPlatformViewsController().attach(
+    flutterEngine.getPlatformViewsController().attach(
         activity,
-        pluginBinding.getFlutterEngine().getRenderer(),
-        pluginBinding.getFlutterEngine().getDartExecutor()
+        flutterEngine.getRenderer(),
+        flutterEngine.getDartExecutor()
     );
 
     // Notify all ActivityAware plugins that they are now attached to a new Activity.
@@ -322,7 +329,7 @@ public void detachFromActivityForConfigChanges() {
       }
 
       // Deactivate PlatformViewsController.
-      pluginBinding.getFlutterEngine().getPlatformViewsController().detach();
+      flutterEngine.getPlatformViewsController().detach();
 
       flutterEngineAndroidLifecycle.setBackingLifecycle(null);
       activity = null;
@@ -341,7 +348,7 @@ public void detachFromActivity() {
       }
 
       // Deactivate PlatformViewsController.
-      pluginBinding.getFlutterEngine().getPlatformViewsController().detach();
+      flutterEngine.getPlatformViewsController().detach();
 
       flutterEngineAndroidLifecycle.setBackingLifecycle(null);
       activity = null;
@@ -392,6 +399,26 @@ public void onUserLeaveHint() {
       Log.e(TAG, "Attempted to notify ActivityAware plugins of onUserLeaveHint, but no Activity was attached.");
     }
   }
+
+  @Override
+  public void onSaveInstanceState(@NonNull Bundle bundle) {
+    Log.v(TAG, "Forwarding onSaveInstanceState() to plugins.");
+    if (isAttachedToActivity()) {
+      activityPluginBinding.onSaveInstanceState(bundle);
+    } else {
+      Log.e(TAG, "Attempted to notify ActivityAware plugins of onSaveInstanceState, but no Activity was attached.");
+    }
+  }
+
+  @Override
+  public void onRestoreInstanceState(@Nullable Bundle bundle) {
+    Log.v(TAG, "Forwarding onRestoreInstanceState() to plugins.");
+    if (isAttachedToActivity()) {
+      activityPluginBinding.onRestoreInstanceState(bundle);
+    } else {
+      Log.e(TAG, "Attempted to notify ActivityAware plugins of onRestoreInstanceState, but no Activity was attached.");
+    }
+  }
   //------- End ActivityControlSurface -----
 
   //----- Start ServiceControlSurface ----
@@ -400,13 +427,13 @@ private boolean isAttachedToService() {
   }
 
   @Override
-  public void attachToService(@NonNull Service service, @NonNull Lifecycle lifecycle, boolean isForeground) {
+  public void attachToService(@NonNull Service service, @Nullable Lifecycle lifecycle, boolean isForeground) {
     Log.v(TAG, "Attaching to a Service: " + service);
     // If we were already attached to an Android component, detach from it.
     detachFromAndroidComponent();
 
     this.service = service;
-    this.servicePluginBinding = new FlutterEngineServicePluginBinding(service);
+    this.servicePluginBinding = new FlutterEngineServicePluginBinding(service, lifecycle);
     flutterEngineAndroidLifecycle.setBackingLifecycle(lifecycle);
 
     // Notify all ServiceAware plugins that they are now attached to a new Service.
@@ -523,16 +550,21 @@ private static class FlutterEngineActivityPluginBinding implements ActivityPlugi
     @NonNull
     private final Activity activity;
     @NonNull
+    private final Lifecycle lifecycle;
+    @NonNull
     private final Set<io.flutter.plugin.common.PluginRegistry.RequestPermissionsResultListener> onRequestPermissionsResultListeners = new HashSet<>();
     @NonNull
     private final Set<io.flutter.plugin.common.PluginRegistry.ActivityResultListener> onActivityResultListeners = new HashSet<>();
     @NonNull
     private final Set<io.flutter.plugin.common.PluginRegistry.NewIntentListener> onNewIntentListeners = new HashSet<>();
     @NonNull
     private final Set<io.flutter.plugin.common.PluginRegistry.UserLeaveHintListener> onUserLeaveHintListeners = new HashSet<>();
+    @NonNull
+    private final Set<OnSaveInstanceStateListener> onSaveInstanceStateListeners = new HashSet<>();
 
-    public FlutterEngineActivityPluginBinding(@NonNull Activity activity) {
+    public FlutterEngineActivityPluginBinding(@NonNull Activity activity, @NonNull Lifecycle lifecycle) {
       this.activity = activity;
+      this.lifecycle = lifecycle;
     }
 
     @Override
@@ -541,6 +573,12 @@ public Activity getActivity() {
       return activity;
     }
 
+    @NonNull
+    @Override
+    public Lifecycle getLifecycle() {
+      return lifecycle;
+    }
+
     @Override
     public void addRequestPermissionsResultListener(@NonNull io.flutter.plugin.common.PluginRegistry.RequestPermissionsResultListener listener) {
       onRequestPermissionsResultListeners.add(listener);
@@ -615,6 +653,16 @@ public void removeOnUserLeaveHintListener(@NonNull io.flutter.plugin.common.Plug
       onUserLeaveHintListeners.remove(listener);
     }
 
+    @Override
+    public void addOnSaveStateListener(@NonNull OnSaveInstanceStateListener listener) {
+      onSaveInstanceStateListeners.add(listener);
+    }
+
+    @Override
+    public void removeOnSaveStateListener(@NonNull OnSaveInstanceStateListener listener) {
+      onSaveInstanceStateListeners.remove(listener);
+    }
+
     /**
      * Invoked by the {@link FlutterEngine} that owns this {@code ActivityPluginBinding} when its
      * associated {@link Activity} has its {@code onUserLeaveHint()} method invoked.
@@ -624,16 +672,41 @@ void onUserLeaveHint() {
         listener.onUserLeaveHint();
       }
     }
+
+    /**
+     * Invoked by the {@link FlutterEngine} that owns this {@code ActivityPluginBinding} when its
+     * associated {@link Activity} or {@code Fragment} has its {@code onSaveInstanceState(Bundle)}
+     * method invoked.
+     */
+    void onSaveInstanceState(@NonNull Bundle bundle) {
+      for (OnSaveInstanceStateListener listener : onSaveInstanceStateListeners) {
+        listener.onSaveInstanceState(bundle);
+      }
+    }
+
+    /**
+     * Invoked by the {@link FlutterEngine} that owns this {@code ActivityPluginBinding} when its
+     * associated {@link Activity} has its {@code onCreate(Bundle)} method invoked, or its
+     * associated {@code Fragment} has its {@code onActivityCreated(Bundle)} method invoked.
+     */
+    void onRestoreInstanceState(@Nullable Bundle bundle) {
+      for (OnSaveInstanceStateListener listener : onSaveInstanceStateListeners) {
+        listener.onRestoreInstanceState(bundle);
+      }
+    }
   }
 
   private static class FlutterEngineServicePluginBinding implements ServicePluginBinding {
     @NonNull
     private final Service service;
+    @Nullable
+    private final Lifecycle lifecycle;
     @NonNull
     private final Set<ServiceAware.OnModeChangeListener> onModeChangeListeners = new HashSet<>();
 
-    FlutterEngineServicePluginBinding(@NonNull Service service) {
+    FlutterEngineServicePluginBinding(@NonNull Service service, @Nullable Lifecycle lifecycle) {
       this.service = service;
+      this.lifecycle = lifecycle;
     }
 
     @Override
@@ -642,6 +715,12 @@ public Service getService() {
       return service;
     }
 
+    @Nullable
+    @Override
+    public Lifecycle getLifecycle() {
+      return lifecycle;
+    }
+
     @Override
     public void addOnModeChangeListener(@NonNull ServiceAware.OnModeChangeListener listener) {
       onModeChangeListeners.add(listener);