addRetained method

EngineLayer addRetained (EngineLayer retainedLayer)

Add a retained engine layer subtree from previous frames.

All the engine layers that are in the subtree of the retained layer will be automatically appended to the current engine layer tree.

Therefore, when implementing a subclas of the Layer concept defined in the rendering layer of Flutter's framework, once this is called, there's no need to call addToScene for its children layers.

Implementation 

EngineLayer addRetained(EngineLayer retainedLayer) native 'SceneBuilder_addRetained';