New Plugin API PR5: Integrates plugin lifecycle control with FlutterFragment. (#9083)

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

@@ -6,6 +6,8 @@ package io.flutter.embedding.android;
 
 import static android.content.ComponentCallbacks2.TRIM_MEMORY_RUNNING_LOW;
 
+import android.arch.lifecycle.Lifecycle;
+import android.arch.lifecycle.LifecycleOwner;
 import android.content.Context;
 import android.content.Intent;
 import android.os.Build;
@@ -349,8 +351,14 @@ public class FlutterFragment extends Fragment {
     if (shouldAttachEngineToActivity()) {
       // Notify any plugins that are currently attached to our FlutterEngine that they
       // are now attached to an Activity.
-      // TODO(mattcarroll): send in a real lifecycle.
-      flutterEngine.getActivityControlSurface().attachToActivity(getActivity(), null);
+      //
+      // Passing this Fragment's Lifecycle should be sufficient because as long as this Fragment
+      // is attached to its Activity, the lifecycles should be in sync. Once this Fragment is
+      // detached from its Activity, that Activity will be detached from the FlutterEngine, too,
+      // which means there shouldn't be any possibility for the Fragment Lifecycle to get out of
+      // sync with the Activity. We use the Fragment's Lifecycle because it is possible that the
+      // attached Activity is not a LifecycleOwner.
+      flutterEngine.getActivityControlSurface().attachToActivity(getActivity(), getLifecycle());
     }
   }
 
@@ -590,8 +598,11 @@ public class FlutterFragment extends Fragment {
 
     if (shouldAttachEngineToActivity()) {
       // Notify plugins that they are no longer attached to an Activity.
-      // TODO(mattcarroll): differentiate between detaching for config changes and otherwise.
-      flutterEngine.getActivityControlSurface().detachFromActivity();
+      if (getActivity().isChangingConfigurations()) {
+        flutterEngine.getActivityControlSurface().detachFromActivityForConfigChanges();
+      } else {
+        flutterEngine.getActivityControlSurface().detachFromActivity();
+      }
     }
 
     // Null out the platformPlugin to avoid a possible retain cycle between the plugin, this Fragment,

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

@@ -53,6 +53,7 @@ class FlutterEnginePluginRegistry implements PluginRegistry,
   private final Map<Class<? extends FlutterPlugin>, ActivityAware> activityAwarePlugins = new HashMap<>();
   private Activity activity;
   private FlutterEngineActivityPluginBinding activityPluginBinding;
+  private boolean isWaitingForActivityReattachment = false;
 
   // ServiceAware
   private final Map<Class<? extends FlutterPlugin>, ServiceAware> serviceAwarePlugins = new HashMap<>();
@@ -259,7 +260,8 @@ class FlutterEnginePluginRegistry implements PluginRegistry,
 
   @Override
   public void attachToActivity(@NonNull Activity activity, @NonNull Lifecycle lifecycle) {
-    Log.d(TAG, "Attaching to an Activity.");
+    Log.v(TAG, "Attaching to an Activity."
+        + (isWaitingForActivityReattachment ? " This is after a config change." : ""));
     // If we were already attached to an Android component, detach from it.
     detachFromAndroidComponent();
 
@@ -269,14 +271,21 @@ class FlutterEnginePluginRegistry implements PluginRegistry,
 
     // Notify all ActivityAware plugins that they are now attached to a new Activity.
     for (ActivityAware activityAware : activityAwarePlugins.values()) {
-      activityAware.onAttachedToActivity(activityPluginBinding);
+      if (isWaitingForActivityReattachment) {
+        activityAware.onReattachedToActivityForConfigChanges(activityPluginBinding);
+      } else {
+        activityAware.onAttachedToActivity(activityPluginBinding);
+      }
     }
+    isWaitingForActivityReattachment = false;
   }
 
   @Override
   public void detachFromActivityForConfigChanges() {
-    Log.d(TAG, "Detaching from an Activity for config changes.");
+    Log.v(TAG, "Detaching from an Activity for config changes.");
     if (isAttachedToActivity()) {
+      isWaitingForActivityReattachment = true;
+
       for (ActivityAware activityAware : activityAwarePlugins.values()) {
         activityAware.onDetachedFromActivityForConfigChanges();
       }
@@ -289,25 +298,9 @@ class FlutterEnginePluginRegistry implements PluginRegistry,
     }
   }
 
-  @Override
-  public void reattachToActivityAfterConfigChange(@NonNull Activity activity, @NonNull Lifecycle lifecycle) {
-    Log.d(TAG, "Re-attaching to an Activity after config change.");
-    if (!isAttachedToActivity()) {
-      this.activity = activity;
-      activityPluginBinding = new FlutterEngineActivityPluginBinding(activity);
-      this.flutterEngineAndroidLifecycle.setBackingLifecycle(lifecycle);
-
-      for (ActivityAware activityAware : activityAwarePlugins.values()) {
-        activityAware.onReattachedToActivityForConfigChanges(activityPluginBinding);
-      }
-    } else {
-      Log.e(TAG, "Attempted to reattach plugins to an Activity after config changes, but an Activity was already attached.");
-    }
-  }
-
   @Override
   public void detachFromActivity() {
-    Log.d(TAG, "Detaching from an Activity.");
+    Log.v(TAG, "Detaching from an Activity.");
     if (isAttachedToActivity()) {
       for (ActivityAware activityAware : activityAwarePlugins.values()) {
         activityAware.onDetachedFromActivity();
@@ -323,7 +316,7 @@ class FlutterEnginePluginRegistry implements PluginRegistry,
 
   @Override
   public boolean onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResult) {
-    Log.d(TAG, "Forwarding onRequestPermissionsResult() to plugins.");
+    Log.v(TAG, "Forwarding onRequestPermissionsResult() to plugins.");
     if (isAttachedToActivity()) {
       return activityPluginBinding.onRequestPermissionsResult(requestCode, permissions, grantResult);
     } else {
@@ -334,7 +327,7 @@ class FlutterEnginePluginRegistry implements PluginRegistry,
 
   @Override
   public boolean onActivityResult(int requestCode, int resultCode, @NonNull Intent data) {
-    Log.d(TAG, "Forwarding onActivityResult() to plugins.");
+    Log.v(TAG, "Forwarding onActivityResult() to plugins.");
     if (isAttachedToActivity()) {
       return activityPluginBinding.onActivityResult(requestCode, resultCode, data);
     } else {
@@ -345,7 +338,7 @@ class FlutterEnginePluginRegistry implements PluginRegistry,
 
   @Override
   public void onNewIntent(@NonNull Intent intent) {
-    Log.d(TAG, "Forwarding onNewIntent() to plugins.");
+    Log.v(TAG, "Forwarding onNewIntent() to plugins.");
     if (isAttachedToActivity()) {
       activityPluginBinding.onNewIntent(intent);
     } else {
@@ -355,7 +348,7 @@ class FlutterEnginePluginRegistry implements PluginRegistry,
 
   @Override
   public void onUserLeaveHint() {
-    Log.d(TAG, "Forwarding onUserLeaveHint() to plugins.");
+    Log.v(TAG, "Forwarding onUserLeaveHint() to plugins.");
     if (isAttachedToActivity()) {
       activityPluginBinding.onUserLeaveHint();
     } else {

shell/platform/android/io/flutter/embedding/engine/plugins/activity/ActivityControlSurface.java

@@ -58,16 +58,6 @@ public interface ActivityControlSurface {
    */
   void detachFromActivityForConfigChanges();
 
-  /**
-   * Call this method from the {@link Activity} that was previously attached to this
-   * {@code ActivityControlSurface}'s {@link FlutterEngine}, and was just recreated after a
-   * configuration change.
-   * <p>
-   * This method gives each {@link ActivityAware} plugin an opportunity to re-establish necessary
-   * references to the given {@link Activity}.
-   */
-  void reattachToActivityAfterConfigChange(@NonNull Activity activity, @NonNull Lifecycle lifecycle);
-
   /**
    * Call this method from the {@link Activity} that is attached to this {@code ActivityControlSurfaces}'s
    * {@link FlutterEngine} when the {@link Activity} is about to be destroyed for non-configuration-change