io.flutter.embedding.engine.FlutterEngineGroup Class Reference

Classes
class	Options

Public Member Functions
	FlutterEngineGroup (@NonNull Context context)
	FlutterEngineGroup (@NonNull Context context, @Nullable String[] dartVmArgs)
FlutterEngine	createAndRunDefaultEngine (@NonNull Context context)
FlutterEngine	createAndRunEngine ( @NonNull Context context, @Nullable DartEntrypoint dartEntrypoint)
FlutterEngine	createAndRunEngine ( @NonNull Context context, @Nullable DartEntrypoint dartEntrypoint, @Nullable String initialRoute)
FlutterEngine	createAndRunEngine (@NonNull Options options)

Package Functions
FlutterEngine	createEngine (Context context, @NonNull PlatformViewsController platformViewsController, boolean automaticallyRegisterPlugins, boolean waitForRestorationData)

Package Attributes
final List< FlutterEngine >	activeEngines = new ArrayList<>()

Detailed Description

Represents a collection of io.flutter.embedding.engine.FlutterEngines who share resources to allow them to be created faster and with less memory than calling the io.flutter.embedding.engine.FlutterEngine's constructor multiple times.

When creating or recreating the first io.flutter.embedding.engine.FlutterEngine in the FlutterEngineGroup, the behavior is the same as creating a io.flutter.embedding.engine.FlutterEngine via its constructor. When subsequent io.flutter.embedding.engine.FlutterEngines are created, resources from an existing living io.flutter.embedding.engine.FlutterEngine is re-used.

The shared resources are kept until the last surviving io.flutter.embedding.engine.FlutterEngine is destroyed.

Deleting a FlutterEngineGroup doesn't invalidate its existing io.flutter.embedding.engine.FlutterEngines, but it eliminates the possibility to create more io.flutter.embedding.engine.FlutterEngines in that group.

Definition at line 36 of file FlutterEngineGroup.java.

Constructor & Destructor Documentation

FlutterEngineGroup() [1/2]

io.flutter.embedding.engine.FlutterEngineGroup.FlutterEngineGroup ( @NonNull Context  context )

inline

Create a FlutterEngineGroup whose child engines will share resources.

Since the FlutterEngineGroup is likely to have a longer lifecycle than any individual Android component, it's more semantically correct to pass in an application context rather than the individual Android component's context to minimize the chances of leaks.

Definition at line 47 of file FlutterEngineGroup.java.

                                                      {
    this(context, null);
  }

FlutterEngineGroup() [2/2]

io.flutter.embedding.engine.FlutterEngineGroup.FlutterEngineGroup ( @NonNull Context  context, @Nullable String[]  dartVmArgs  )

inline

Create a FlutterEngineGroup whose child engines will share resources. Use dartVmArgs to pass flags to the Dart VM during initialization.

Since the FlutterEngineGroup is likely to have a longer lifecycle than any individual Android component, it's more semantically correct to pass in an application context rather than the individual Android component's context to minimize the chances of leaks.

Definition at line 59 of file FlutterEngineGroup.java.

                                                                                     {
    FlutterLoader loader = FlutterInjector.instance().flutterLoader();
    if (!loader.initialized()) {
      loader.startInitialization(context.getApplicationContext());
      loader.ensureInitializationComplete(context.getApplicationContext(), dartVmArgs);
    }
  }

Member Function Documentation

createAndRunDefaultEngine()

FlutterEngine io.flutter.embedding.engine.FlutterEngineGroup.createAndRunDefaultEngine ( @NonNull Context  context )

inline

Creates a io.flutter.embedding.engine.FlutterEngine in this group and run its io.flutter.embedding.engine.dart.DartExecutor with a default entrypoint of the "main" function in the "lib/main.dart" file.

If no prior io.flutter.embedding.engine.FlutterEngine were created in this group, the initialization cost will be slightly higher than subsequent engines. The very first io.flutter.embedding.engine.FlutterEngine created per program, regardless of FlutterEngineGroup, also incurs the Dart VM creation time.

Subsequent engine creations will share resources with existing engines. However, if all existing engines were io.flutter.embedding.engine.FlutterEngine#destroy()ed, the next engine created will recreate its dependencies.

Definition at line 81 of file FlutterEngineGroup.java.

                                                                           {
    return createAndRunEngine(context, null);
  }

createAndRunEngine() [1/3]

FlutterEngine io.flutter.embedding.engine.FlutterEngineGroup.createAndRunEngine ( @NonNull Context  context, @Nullable DartEntrypoint  dartEntrypoint  )

inline

Creates a io.flutter.embedding.engine.FlutterEngine in this group and run its io.flutter.embedding.engine.dart.DartExecutor with the specified DartEntrypoint.

If no prior io.flutter.embedding.engine.FlutterEngine were created in this group, the initialization cost will be slightly higher than subsequent engines. The very first io.flutter.embedding.engine.FlutterEngine created per program, regardless of FlutterEngineGroup, also incurs the Dart VM creation time.

Subsequent engine creations will share resources with existing engines. However, if all existing engines were io.flutter.embedding.engine.FlutterEngine#destroy()ed, the next engine created will recreate its dependencies.

Definition at line 98 of file FlutterEngineGroup.java.

                                                                         {
    return createAndRunEngine(context, dartEntrypoint, null);
  }

createAndRunEngine() [2/3]

FlutterEngine io.flutter.embedding.engine.FlutterEngineGroup.createAndRunEngine ( @NonNull Context  context, @Nullable DartEntrypoint  dartEntrypoint, @Nullable String  initialRoute  )

inline

Creates a io.flutter.embedding.engine.FlutterEngine in this group and run its io.flutter.embedding.engine.dart.DartExecutor with the specified DartEntrypoint and the specified initialRoute.

If no prior io.flutter.embedding.engine.FlutterEngine were created in this group, the initialization cost will be slightly higher than subsequent engines. The very first io.flutter.embedding.engine.FlutterEngine created per program, regardless of FlutterEngineGroup, also incurs the Dart VM creation time.

Subsequent engine creations will share resources with existing engines. However, if all existing engines were io.flutter.embedding.engine.FlutterEngine#destroy()ed, the next engine created will recreate its dependencies.

Definition at line 117 of file FlutterEngineGroup.java.

                                     {
    return createAndRunEngine(
        new Options(context).setDartEntrypoint(dartEntrypoint).setInitialRoute(initialRoute));
  }

createAndRunEngine() [3/3]

FlutterEngine io.flutter.embedding.engine.FlutterEngineGroup.createAndRunEngine ( @NonNull Options  options )

inline

Creates a io.flutter.embedding.engine.FlutterEngine in this group and run its io.flutter.embedding.engine.dart.DartExecutor with the specified DartEntrypoint, the specified initialRoute and the dartEntrypointArgs.

If no prior io.flutter.embedding.engine.FlutterEngine were created in this group, the initialization cost will be slightly higher than subsequent engines. The very first io.flutter.embedding.engine.FlutterEngine created per program, regardless of FlutterEngineGroup, also incurs the Dart VM creation time.

Subsequent engine creations will share resources with existing engines. However, if all existing engines were io.flutter.embedding.engine.FlutterEngine#destroy()ed, the next engine created will recreate its dependencies.

Definition at line 139 of file FlutterEngineGroup.java.

                                                                    {
    FlutterEngine engine = null;
 
    Context context = options.getContext();
    DartEntrypoint dartEntrypoint = options.getDartEntrypoint();
    String initialRoute = options.getInitialRoute();
    List<String> dartEntrypointArgs = options.getDartEntrypointArgs();
    PlatformViewsController platformViewsController = options.getPlatformViewsController();
    platformViewsController =
        platformViewsController != null ? platformViewsController : new PlatformViewsController();
    boolean automaticallyRegisterPlugins = options.getAutomaticallyRegisterPlugins();
    boolean waitForRestorationData = options.getWaitForRestorationData();
 
    if (dartEntrypoint == null) {
      dartEntrypoint = DartEntrypoint.createDefault();
    }
 
    if (activeEngines.size() == 0) {
      engine =
          createEngine(
              context,
              platformViewsController,
              automaticallyRegisterPlugins,
              waitForRestorationData);
      if (initialRoute != null) {
        engine.getNavigationChannel().setInitialRoute(initialRoute);
      }
      engine.getDartExecutor().executeDartEntrypoint(dartEntrypoint, dartEntrypointArgs);
    } else {
      engine =
          activeEngines
              .get(0)
              .spawn(
                  context,
                  dartEntrypoint,
                  initialRoute,
                  dartEntrypointArgs,
                  platformViewsController,
                  automaticallyRegisterPlugins,
                  waitForRestorationData);
    }
 
    activeEngines.add(engine);
 
    final FlutterEngine engineToCleanUpOnDestroy = engine;
    engine.addEngineLifecycleListener(
        new FlutterEngine.EngineLifecycleListener() {
 
          @Override
          public void onPreEngineRestart() {
            // No-op. Not interested.
          }
 
          @Override
          public void onEngineWillDestroy() {
            activeEngines.remove(engineToCleanUpOnDestroy);
          }
        });
    return engine;
  }

createEngine()

FlutterEngine io.flutter.embedding.engine.FlutterEngineGroup.createEngine ( Context  context, @NonNull PlatformViewsController  platformViewsController, boolean  automaticallyRegisterPlugins, boolean  waitForRestorationData  )

inlinepackage

Definition at line 201 of file FlutterEngineGroup.java.

                                      {
    return new FlutterEngine(
        context, // Context.
        null, // FlutterLoader.
        null, // FlutterJNI.
        platformViewsController, // PlatformViewsController.
        null, // String[]. The Dart VM has already started, this arguments will have no effect.
        automaticallyRegisterPlugins, // boolean.
        waitForRestorationData, // boolean.
        this);
  }

Member Data Documentation

activeEngines

final List<FlutterEngine> io.flutter.embedding.engine.FlutterEngineGroup.activeEngines = new ArrayList<>()

package

Definition at line 38 of file FlutterEngineGroup.java.

---

The documentation for this class was generated from the following file:

• shell/platform/android/io/flutter/embedding/engine/FlutterEngineGroup.java