obtainLayoutTransform method
Implementation
Offset obtainLayoutTransform(RenderObject child, bool excludeScrollOffset) {
  assert(child.parent == this);
  assert(child.parentData is BoxParentData);
  final BoxParentData childParentData = child.parentData! as BoxParentData;
  Offset offset = childParentData.offset;
  if (excludeScrollOffset) {
    offset -= Offset(scrollLeft, scrollTop);
  }
  return offset;
}