defaultChildFactory<T extends InflatedChildHandle> static method

T defaultChildFactory<T extends InflatedChildHandle>({ required Object id, required InflatingRenderObjectMixin<RenderObject, InflatingParentData<RenderObject>, InflatedChildHandle> parent, RenderObject? render, Element? context, Widget? widget, })

The default child handle factory for BaseBoxyChild subclasses, constructs an appropriate child based on the the generic type argument.

Implementation

static T defaultChildFactory<T extends InflatedChildHandle>({
  required Object id,
  required InflatingRenderObjectMixin parent,
  RenderObject? render,
  Element? context,
  Widget? widget,
}) {
  R? expectType<R extends RenderObject>() {
    assert(() {
      if (render != null && render is! R) {
        throw FlutterError(
          'A ${parent.context.widget} widget was given a child of the wrong type: $render\n'
          'Expected child of type $R\n',
        );
      }
      return true;
    }());
    return render as R?;
  }

  final BaseBoxyChild handle;
  if (render is RenderBox || T == BoxyChild) {
    handle = BoxyChild(
      id: id,
      parent: parent,
      widget: widget,
      render: expectType(),
      context: context,
    );
  } else if (render is RenderSliver || T == SliverBoxyChild) {
    handle = SliverBoxyChild(
      id: id,
      parent: parent,
      widget: widget,
      render: expectType(),
      context: context,
    );
  } else if (T == BaseBoxyChild) {
    handle = BaseBoxyChild(
      id: id,
      parent: parent,
      widget: widget,
      render: render,
      context: context,
    );
  } else {
    throw FlutterError(
        'A ${parent.context.widget} widget was given a child with an unknown type: $render\n'
        'No child factory is available for $T\n');
  }

  return handle as T;
}