alwaysNeedsCompositing property
override
Whether this render object always needs compositing.
Override this in subclasses to indicate that your paint function always creates at least one composited layer. For example, videos should return true if they use hardware decoders.
You must call markNeedsCompositingBitsUpdate if the value of this getter changes. (This is implied when adoptChild or dropChild are called.)
Implementation
@override
bool get alwaysNeedsCompositing => child != null && _alpha > 0;