如何获取 ListView 中的起始索引和可见项的数量？

ScrollController _scrollController = ScrollController();
ListView.builder(
  controller: _scrollController,
  // 其他属性
);

int getStartIndex() {
  int startIndex = _scrollController.offset ~/ itemHeight;
  return startIndex;
}

int getVisibleItemCount() {
  int visibleItemCount = (_scrollController.position.maxScrollExtent - _scrollController.offset) ~/ itemHeight;
  return visibleItemCount;
}

int startIndex = getStartIndex();
int visibleItemCount = getVisibleItemCount();