Get rid of FlutterNativeView, introduce FlutterEngine and FlutterRenderer

ci/licenses_golden/licenses_flutter

@@ -93,7 +93,6 @@ FILE: ../../../flutter/shell/platform/android/io/flutter/app/FlutterActivityDele
 FILE: ../../../flutter/shell/platform/android/io/flutter/app/FlutterActivityEvents.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/app/FlutterFragmentActivity.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/app/FlutterPluginRegistry.java
-FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/legacy/FlutterNativeView.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/legacy/FlutterPluginRegistry.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/legacy/PluginRegistry.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/plugin/common/BasicMessageChannel.java
@@ -202,6 +201,9 @@ FILE: ../../../flutter/lib/ui/natives.dart
 FILE: ../../../flutter/lib/ui/window/window.h
 FILE: ../../../flutter/shell/common/skia_event_tracer_impl.cc
 FILE: ../../../flutter/shell/platform/android/apk_asset_provider.cc
+FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/FlutterEngine.java
+FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/FlutterJNI.java
+FILE: ../../../flutter/shell/platform/android/io/flutter/embedding/FlutterRenderer.java
 FILE: ../../../flutter/shell/platform/android/io/flutter/plugin/common/JSONUtil.java
 FILE: ../../../flutter/shell/platform/darwin/desktop/Info.plist
 FILE: ../../../flutter/shell/platform/darwin/ios/framework/Flutter.podspec

shell/platform/android/BUILD.gn

@@ -97,6 +97,24 @@ java_library("flutter_shell_java") {
   supports_android = true
 
   java_files = [
+    "io/flutter/embedding/FlutterActivity.java",
+    "io/flutter/embedding/FlutterEngine.java",
+    "io/flutter/embedding/FlutterFragment.java",
+    "io/flutter/embedding/FlutterJNI.java",
+    "io/flutter/embedding/FlutterRenderer.java",
+    "io/flutter/embedding/FlutterShellArgs.java",
+    "io/flutter/embedding/FlutterView.java",
+    "io/flutter/embedding/legacy/AccessibilityBridge.java",
+    "io/flutter/embedding/legacy/FlutterPluginRegistry.java",
+    "io/flutter/embedding/legacy/InputConnectionAdaptor.java",
+    "io/flutter/embedding/legacy/PlatformViewFactory.java",
+    "io/flutter/embedding/legacy/PlatformViewRegistry.java",
+    "io/flutter/embedding/legacy/PlatformViewRegistryImpl.java",
+    "io/flutter/embedding/legacy/PlatformViewsController.java",
+    "io/flutter/embedding/legacy/PluginRegistry.java",
+    "io/flutter/embedding/legacy/SingleViewPresentation.java",
+    "io/flutter/embedding/legacy/TextInputPlugin.java",
+    "io/flutter/embedding/legacy/VirtualDisplayController.java",
     "io/flutter/app/FlutterActivity.java",
     "io/flutter/app/FlutterActivityDelegate.java",
     "io/flutter/app/FlutterActivityEvents.java",

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

@@ -16,11 +16,13 @@
 import android.os.Bundle;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
+import android.util.Log;
 import android.view.ViewGroup;
 import android.view.Window;
 import android.view.WindowManager;
 import android.widget.FrameLayout;
 
+import io.flutter.embedding.legacy.PluginRegistry;
 import io.flutter.plugin.platform.PlatformPlugin;
 import io.flutter.view.FlutterMain;
 
@@ -65,6 +67,7 @@ public class FlutterActivity extends Activity {
   @Override
   public void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
+    Log.d(TAG, "onCreate()");
 
     FlutterShellArgs args = FlutterShellArgs.fromIntent(getIntent());
     // TODO(mattcarroll): Change FlutterMain to accept FlutterShellArgs and move additional constants in
@@ -79,6 +82,7 @@ public void onCreate(Bundle savedInstanceState) {
   @Override
   public void onPostResume() {
     super.onPostResume();
+    Log.d(TAG, "onPostResume()");
     flutterFragment.onPostResume();
   }
 
@@ -90,6 +94,7 @@ protected void onNewIntent(Intent intent) {
 
   @Override
   public void onBackPressed() {
+    Log.d(TAG, "onBackPressed()");
     flutterFragment.onBackPressed();
   }
 
@@ -102,11 +107,17 @@ public void onUserLeaveHint() {
     flutterFragment.onUserLeaveHint();
   }
 
+  @Nullable
+  protected FlutterEngine getFlutterEngine() {
+    return flutterFragment.getFlutterEngine();
+  }
+
   /**
    * Sets up a {@code FrameLayout} that takes up all available space in the {@code Activity}. This
    * {@code FrameLayout} will hold a {@code FlutterFragment}, which displays a {@code FlutterView}.
    */
   private void createFlutterFragmentContainer() {
+    Log.d(TAG, "createFlutterFragmentContainer()");
     FrameLayout container = new FrameLayout(this);
     container.setId(CONTAINER_ID);
     container.setLayoutParams(new ViewGroup.LayoutParams(
@@ -122,6 +133,7 @@ private void createFlutterFragmentContainer() {
    * a reference to that {@code FlutterFragment} is retained in {@code flutterFragment}.
    */
   private void createFlutterFragment() {
+    Log.d(TAG, "createFlutterFragment()");
     FragmentManager fragmentManager = getFragmentManager();
 
     flutterFragment = (FlutterFragment) fragmentManager.findFragmentByTag(TAG_FLUTTER_FRAGMENT);

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

@@ -0,0 +1,262 @@
+package io.flutter.embedding;
+
+import android.app.Activity;
+import android.content.Context;
+import android.content.res.Resources;
+import android.util.Log;
+
+import java.nio.ByteBuffer;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import io.flutter.embedding.legacy.FlutterPluginRegistry;
+import io.flutter.plugin.common.BinaryMessenger;
+import io.flutter.view.FlutterRunArguments;
+
+/**
+ * A single Flutter execution environment.
+ *
+ * A {@code FlutterEngine} can execute in the background, or it can be rendered to the screen by
+ * using the accompanying {@link FlutterRenderer}.  Rendering can be started and stopped, thus
+ * allowing a {@code FlutterEngine} to move from UI interaction to data-only processing and then
+ * back to UI interaction.
+ *
+ * To start running Flutter within this {@code FlutterEngine}, use {@link #runFromBundle(FlutterRunArguments)}.
+ * The {@link #runFromBundle(FlutterRunArguments)} method must not be invoked twice on the same
+ * {@code FlutterEngine}.
+ *
+ * To start rendering Flutter content to the screen, use {@link #getRenderer()} to obtain a
+ * {@link FlutterRenderer} and then attach a {@link FlutterRenderer.RenderSurface}.  Consider using
+ * a {@link FlutterView} as a {@link FlutterRenderer.RenderSurface}.
+ * TODO(mattcarroll): for the above instructions for RenderSurface to be true, we need to refactor
+ *                    the native relationships and also the PlatformViewsController relationship.
+ */
+public class FlutterEngine implements BinaryMessenger {
+  private static final String TAG = "FlutterEngine";
+
+  private final Resources resources;
+  private final FlutterJNI flutterJNI;
+  private final FlutterRenderer renderer;
+  private final FlutterPluginRegistry pluginRegistry;
+  private final Map<String, BinaryMessageHandler> mMessageHandlers;
+  private final Map<Integer, BinaryReply> mPendingReplies = new HashMap<>();
+  private long nativeObjectReference;
+  private boolean isBackgroundView; // TODO(mattcarroll): rename to something without "view"
+  private boolean applicationIsRunning;
+  private int mNextReplyId = 1;
+
+  public FlutterEngine(
+      Context context,
+      Resources resources,
+      boolean isBackgroundView
+  ) {
+    this.flutterJNI = new FlutterJNI();
+    this.resources = resources;
+    this.isBackgroundView = isBackgroundView;
+    pluginRegistry = new FlutterPluginRegistry(this, context);
+    mMessageHandlers = new HashMap<>();
+
+    attach();
+    // TODO(mattcarroll): FlutterRenderer is temporally coupled to attach(). Remove that coupling if possible.
+    this.renderer = new FlutterRenderer(flutterJNI, nativeObjectReference);
+  }
+
+  private void attach() {
+    // TODO(mattcarroll): what impact does "isBackgroundView' have?
+    nativeObjectReference = flutterJNI.nativeAttach(this, isBackgroundView);
+
+    if (!isAttached()) {
+      throw new RuntimeException("FlutterEngine failed to attach to its native Object reference.");
+    }
+  }
+
+  private void assertAttached() {
+    if (!isAttached()) throw new AssertionError("Platform view is not attached");
+  }
+
+  @SuppressWarnings("BooleanMethodIsAlwaysInverted")
+  private boolean isAttached() {
+    return nativeObjectReference != 0;
+  }
+
+  public void detach() {
+    pluginRegistry.detach();
+    // TODO(mattcarroll): why do we have a nativeDetach() method? can we get rid of this?
+    flutterJNI.nativeDetach(nativeObjectReference);
+  }
+
+  public void destroy() {
+    pluginRegistry.destroy();
+    flutterJNI.nativeDestroy(nativeObjectReference);
+    nativeObjectReference = 0;
+    applicationIsRunning = false;
+  }
+
+  public void runFromBundle(FlutterRunArguments args) {
+    if (args.bundlePath == null) {
+      throw new AssertionError("A bundlePath must be specified");
+    } else if (args.entrypoint == null) {
+      throw new AssertionError("An entrypoint must be specified");
+    }
+    runFromBundleInternal(args.bundlePath, args.entrypoint, args.libraryPath, args.defaultPath);
+  }
+
+  private void runFromBundleInternal(
+      String bundlePath,
+      String entrypoint,
+      String libraryPath,
+      String defaultPath
+  ) {
+    assertAttached();
+
+    if (applicationIsRunning) {
+      throw new AssertionError("This Flutter engine instance is already running an application");
+    }
+
+    flutterJNI.nativeRunBundleAndSnapshotFromLibrary(nativeObjectReference, bundlePath,
+        defaultPath, entrypoint, libraryPath, resources.getAssets());
+
+    applicationIsRunning = true;
+  }
+
+  public boolean isApplicationRunning() {
+    return applicationIsRunning;
+  }
+
+  // TODO(mattcarroll): what does this callback actually represent?
+  // Called by native to notify when the engine is restarted (cold reload).
+  @SuppressWarnings("unused")
+  private void onPreEngineRestart() {
+    if (pluginRegistry == null)
+      return;
+    pluginRegistry.onPreEngineRestart();
+  }
+
+  public FlutterRenderer getRenderer() {
+    return renderer;
+  }
+
+  public FlutterPluginRegistry getPluginRegistry() {
+    return pluginRegistry;
+  }
+
+  // TODO(mattcarroll): Is this method really all about plugins? or does it have other implications?
+  public void attachViewAndActivity(Activity activity) {
+    pluginRegistry.attach(this, activity);
+  }
+
+  // TODO(mattcarroll): Implement observatory lookup for "flutter attach"
+  public String getObservatoryUrl() {
+    return flutterJNI.nativeGetObservatoryUri();
+  }
+
+  //------- START ISOLATE METHOD CHANNEL COMMS ------
+  @Override
+  public void setMessageHandler(String channel, BinaryMessageHandler handler) {
+    if (handler == null) {
+      mMessageHandlers.remove(channel);
+    } else {
+      mMessageHandlers.put(channel, handler);
+    }
+  }
+
+  @Override
+  public void send(String channel, ByteBuffer message) {
+    send(channel, message, null);
+  }
+
+  @Override
+  public void send(String channel, ByteBuffer message, BinaryReply callback) {
+    if (!isAttached()) {
+      Log.d(TAG, "FlutterView.send called on a detached view, channel=" + channel);
+      return;
+    }
+
+    int replyId = 0;
+    if (callback != null) {
+      replyId = mNextReplyId++;
+      mPendingReplies.put(replyId, callback);
+    }
+    if (message == null) {
+      flutterJNI.nativeDispatchEmptyPlatformMessage(nativeObjectReference, channel, replyId);
+    } else {
+      flutterJNI.nativeDispatchPlatformMessage(
+          nativeObjectReference, channel, message, message.position(), replyId);
+    }
+  }
+
+  // Called by native to send us a platform message.
+  @SuppressWarnings("unused")
+  private void handlePlatformMessage(final String channel, byte[] message, final int replyId) {
+    assertAttached();
+    BinaryMessageHandler handler = mMessageHandlers.get(channel);
+    if (handler != null) {
+      try {
+        final ByteBuffer buffer = (message == null ? null : ByteBuffer.wrap(message));
+        handler.onMessage(buffer, new BinaryReply() {
+          private final AtomicBoolean done = new AtomicBoolean(false);
+          @Override
+          public void reply(ByteBuffer reply) {
+            if (!isAttached()) {
+              Log.d(TAG,
+                  "handlePlatformMessage replying to a detached view, channel="
+                      + channel);
+              return;
+            }
+            if (done.getAndSet(true)) {
+              throw new IllegalStateException("Reply already submitted");
+            }
+            if (reply == null) {
+              flutterJNI.nativeInvokePlatformMessageEmptyResponseCallback(nativeObjectReference, replyId);
+            } else {
+              flutterJNI.nativeInvokePlatformMessageResponseCallback(nativeObjectReference, replyId, reply, reply.position());
+            }
+          }
+        });
+      } catch (Exception ex) {
+        Log.e(TAG, "Uncaught exception in binary message listener", ex);
+        flutterJNI.nativeInvokePlatformMessageEmptyResponseCallback(nativeObjectReference, replyId);
+      }
+      return;
+    }
+    flutterJNI.nativeInvokePlatformMessageEmptyResponseCallback(nativeObjectReference, replyId);
+  }
+
+  // Called by native to respond to a platform message that we sent.
+  @SuppressWarnings("unused")
+  private void handlePlatformMessageResponse(int replyId, byte[] reply) {
+    BinaryReply callback = mPendingReplies.remove(replyId);
+    if (callback != null) {
+      try {
+        callback.reply(reply == null ? null : ByteBuffer.wrap(reply));
+      } catch (Exception ex) {
+        Log.e(TAG, "Uncaught exception in binary message reply handler", ex);
+      }
+    }
+  }
+  //------- END ISOLATE METHOD CHANNEL COMMS -----
+
+  //------ START NATIVE CALLBACKS THAT SHOULD BE MOVED TO FlutterRenderer ------
+  // Called by native to update the semantics/accessibility tree.
+  @SuppressWarnings("unused")
+  private void updateSemantics(ByteBuffer buffer, String[] strings) {
+    Log.d(TAG, "updateSemantics()");
+    renderer.updateSemantics(buffer, strings);
+  }
+
+  // Called by native to update the custom accessibility actions.
+  @SuppressWarnings("unused")
+  private void updateCustomAccessibilityActions(ByteBuffer buffer, String[] strings) {
+    Log.d(TAG, "updateCustomAccessibilityActions()");
+    renderer.updateCustomAccessibilityActions(buffer, strings);
+  }
+
+  // Called by native to notify first Flutter frame rendered.
+  @SuppressWarnings("unused")
+  private void onFirstFrame() {
+    Log.d(TAG, "onFirstFrame()");
+    renderer.onFirstFrameRendered();
+  }
+  //------ END NATIVE CALLBACKS THAT SHOULD BE MOVED TO FlutterRenderer ------
+}