io.flutter.embedding.android

Class FlutterFragment.CachedEngineFragmentBuilder

java.lang.Object

io.flutter.embedding.android.FlutterFragment.CachedEngineFragmentBuilder

Enclosing class:

FlutterFragment

public static class FlutterFragment.CachedEngineFragmentBuilder
extends Object

Builder that creates a new FlutterFragment that uses a cached FlutterEngine with arguments that correspond to the values set on this Builder.

Subclasses of FlutterFragment that do not introduce any new arguments can use this Builder to construct instances of the subclass without subclassing this Builder. MyFlutterFragment f = new FlutterFragment.CachedEngineFragmentBuilder(MyFlutterFragment.class) .someProperty(...) .someOtherProperty(...) .build<MyFlutterFragment>();

Subclasses of FlutterFragment that introduce new arguments should subclass this CachedEngineFragmentBuilder to add the new properties:

1. Ensure the FlutterFragment subclass has a no-arg constructor.
2. Subclass this CachedEngineFragmentBuilder.
3. Override the new CachedEngineFragmentBuilder's no-arg constructor and invoke the super constructor to set the FlutterFragment subclass: public MyBuilder() { super(MyFlutterFragment.class); }
4. Add appropriate property methods for the new properties.
5. Override createArgs(), call through to the super method, then add the new properties as arguments in the Bundle.

Once a CachedEngineFragmentBuilder subclass is defined, the FlutterFragment subclass can be instantiated as follows. MyFlutterFragment f = new MyBuilder() .someExistingProperty(...) .someNewProperty(...) .build<MyFlutterFragment>();

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	CachedEngineFragmentBuilder(Class<? extends FlutterFragment> subclass, String engineId)

Method Summary

Modifier and Type	Method and Description
<T extends FlutterFragment> T	build() Constructs a new FlutterFragment (or a subclass) that is configured based on properties set on this CachedEngineFragmentBuilder.
protected Bundle	createArgs() Creates a Bundle of arguments that are assigned to the new FlutterFragment.
FlutterFragment.CachedEngineFragmentBuilder	destroyEngineWithFragment(boolean destroyEngineWithFragment) Pass true to destroy the cached FlutterEngine when this FlutterFragment is destroyed, or false for the cached FlutterEngine to outlive this FlutterFragment.
FlutterFragment.CachedEngineFragmentBuilder	renderMode(RenderMode renderMode) Render Flutter either as a RenderMode.surface or a RenderMode.texture.
FlutterFragment.CachedEngineFragmentBuilder	shouldAttachEngineToActivity(boolean shouldAttachEngineToActivity) Whether or not this FlutterFragment should automatically attach its Activity as a control surface for its FlutterEngine.
FlutterFragment.CachedEngineFragmentBuilder	transparencyMode(TransparencyMode transparencyMode) Support a TransparencyMode.transparent background within FlutterView, or force an TransparencyMode.opaque background.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CachedEngineFragmentBuilder

protected CachedEngineFragmentBuilder(@NonNull
                                      Class<? extends FlutterFragment> subclass,
                                      @NonNull
                                      String engineId)

Method Detail

destroyEngineWithFragment

@NonNull
public FlutterFragment.CachedEngineFragmentBuilder destroyEngineWithFragment(boolean destroyEngineWithFragment)

Pass true to destroy the cached FlutterEngine when this FlutterFragment is destroyed, or false for the cached FlutterEngine to outlive this FlutterFragment.

renderMode

@NonNull
public FlutterFragment.CachedEngineFragmentBuilder renderMode(@NonNull
                                                                       RenderMode renderMode)

Render Flutter either as a RenderMode.surface or a RenderMode.texture. You should use surface unless you have a specific reason to use texture. texture comes with a significant performance impact, but texture can be displayed beneath other Android Views and animated, whereas surface cannot.

transparencyMode

@NonNull
public FlutterFragment.CachedEngineFragmentBuilder transparencyMode(@NonNull
                                                                             TransparencyMode transparencyMode)

Support a TransparencyMode.transparent background within FlutterView, or force an TransparencyMode.opaque background.

See TransparencyMode for implications of this selection.

shouldAttachEngineToActivity

@NonNull
public FlutterFragment.CachedEngineFragmentBuilder shouldAttachEngineToActivity(boolean shouldAttachEngineToActivity)

Whether or not this FlutterFragment should automatically attach its Activity as a control surface for its FlutterEngine.

Control surfaces are used to provide Android resources and lifecycle events to plugins that are attached to the FlutterEngine. If shouldAttachEngineToActivity is true then this FlutterFragment will connect its FlutterEngine to the surrounding Activity, along with any plugins that are registered with that FlutterEngine. This allows plugins to access the Activity, as well as receive Activity-specific calls, e.g., Activity.onNewIntent(Intent). If shouldAttachEngineToActivity is false, then this FlutterFragment will not automatically manage the connection between its FlutterEngine and the surrounding Activity. The Activity will need to be manually connected to this FlutterFragment's FlutterEngine by the app developer. See FlutterEngine.getActivityControlSurface().

One reason that a developer might choose to manually manage the relationship between the Activity and FlutterEngine is if the developer wants to move the FlutterEngine somewhere else. For example, a developer might want the FlutterEngine to outlive the surrounding Activity so that it can be used later in a different Activity. To accomplish this, the FlutterEngine will need to be disconnected from the surrounding Activity at an unusual time, preventing this FlutterFragment from correctly managing the relationship between the FlutterEngine and the surrounding Activity.

Another reason that a developer might choose to manually manage the relationship between the Activity and FlutterEngine is if the developer wants to prevent, or explicitly control when the FlutterEngine's plugins have access to the surrounding Activity. For example, imagine that this FlutterFragment only takes up part of the screen and the app developer wants to ensure that none of the Flutter plugins are able to manipulate the surrounding Activity. In this case, the developer would not want the FlutterEngine to have access to the Activity, which can be accomplished by setting shouldAttachEngineToActivity to false.

createArgs

@NonNull
protected Bundle createArgs()

Creates a Bundle of arguments that are assigned to the new FlutterFragment.

Subclasses should override this method to add new properties to the Bundle. Subclasses must call through to the super method to collect all existing property values.

build

@NonNull
public <T extends FlutterFragment> T build()

Constructs a new FlutterFragment (or a subclass) that is configured based on properties set on this CachedEngineFragmentBuilder.