如何在使用bloc滚动时隐藏底部控件

// 在bloc中定义状态和方法
class ScrollBloc extends Bloc<ScrollEvent, bool> {
  bool isBottomControlVisible = true;

  @override
  bool get initialState => isBottomControlVisible;

  @override
  Stream<bool> mapEventToState(ScrollEvent event) async* {
    if (event is ScrollToBottomEvent) {
      isBottomControlVisible = false;
    } else {
      isBottomControlVisible = true;
    }
    yield isBottomControlVisible;
  }
}

// 在界面中使用BlocBuilder监听状态变化
class ScrollPage extends StatelessWidget {
  final scrollBloc = ScrollBloc();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Scroll Page'),
      ),
      body: BlocBuilder<ScrollBloc, bool>(
        bloc: scrollBloc,
        builder: (context, isBottomControlVisible) {
          return ListView.builder(
            itemCount: 100,
            itemBuilder: (context, index) {
              return ListTile(
                title: Text('Item $index'),
              );
            },
            controller: ScrollController(
              // 监听滚动事件
              onScroll: () {
                if (isBottomControlVisible) {
                  if (isScrollAtBottom()) {
                    scrollBloc.add(ScrollToBottomEvent());
                  }
                } else {
                  if (!isScrollAtBottom()) {
                    scrollBloc.add(ScrollToTopEvent());
                  }
                }
              },
            ),
          );
        },
      ),
      bottomNavigationBar: BlocBuilder<ScrollBloc, bool>(
        bloc: scrollBloc,
        builder: (context, isBottomControlVisible) {
          return isBottomControlVisible
              ? BottomNavigationBar(
                  items: [
                    BottomNavigationBarItem(
                      icon: Icon(Icons.home),
                      label: 'Home',
                    ),
                    BottomNavigationBarItem(
                      icon: Icon(Icons.settings),
                      label: 'Settings',
                    ),
                  ],
                )
              : SizedBox();
        },
      ),
    );
  }

  bool isScrollAtBottom() {
    // 判断滚动位置是否在底部
    // 实现逻辑省略
    return false;
  }
}

// 定义滚动事件
abstract class ScrollEvent {}

class ScrollToBottomEvent extends ScrollEvent {}

class ScrollToTopEvent extends ScrollEvent {}