Package io.flutter.embedding.engine

Class FlutterEngineGroup

  • public class FlutterEngineGroup
extends Object
    Represents a collection of FlutterEngines who share resources to allow them to be created faster and with less memory than calling the FlutterEngine's constructor multiple times.

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

    The shared resources are kept until the last surviving FlutterEngine is destroyed.

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

    • Constructor Detail

      • FlutterEngineGroup

        public FlutterEngineGroup​(@NonNull
                          Context context)
        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.

      • FlutterEngineGroup

        public FlutterEngineGroup​(@NonNull
                          Context context,
                          @Nullable
                          String[] dartVmArgs)
        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.

    • Method Detail

      • createAndRunDefaultEngine

        public FlutterEngine createAndRunDefaultEngine​(@NonNull
                                               Context context)
        Creates a FlutterEngine in this group and run its DartExecutor with a default entrypoint of the "main" function in the "lib/main.dart" file.

        If no prior FlutterEngine were created in this group, the initialization cost will be slightly higher than subsequent engines. The very first 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 FlutterEngine.destroy()ed, the next engine created will recreate its dependencies.

      • createAndRunEngine

        public FlutterEngine createAndRunEngine​(@NonNull
                                        FlutterEngineGroup.Options options)
        Creates a FlutterEngine in this group and run its DartExecutor with the specified DartExecutor.DartEntrypoint, the specified initialRoute and the dartEntrypointArgs.

        If no prior FlutterEngine were created in this group, the initialization cost will be slightly higher than subsequent engines. The very first 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 FlutterEngine.destroy()ed, the next engine created will recreate its dependencies.