SemanticsBuilderCallback typedef Null safety
Signature of the function returned by CustomPainter.semanticsBuilder.
Builds semantics information describing the picture drawn by a CustomPainter. Each CustomPainterSemantics in the returned list is converted into a SemanticsNode by copying its properties.
The returned list must not be mutated after this function completes. To change the semantic information, the function must return a new list instead.
typedef SemanticsBuilderCallback = List<CustomPainterSemantics> Function(Size size);