如何在向下滚动时隐藏TextField，向上滚动时再次显示？

Question

我不知道该怎么做我找到了几种不同的方法，但它们不太适合我。

我尝试使用SilverAppBar，但是我不能做我想做的事。现在我使用可隐藏的：^1.0.3 库
有了它我得到了我想要的但是当我向下滚动时 TextField 消失并且当我向上滚动时不出现 我的代码

class HomeScreen extends StatefulWidget {
  HomeScreen({Key? key}) : super(key: key);

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  final ScrollController scrollController = ScrollController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.black,
      appBar: buildAppBar(),
      body: Stack(
        children: [
          Container(
            margin: EdgeInsets.symmetric(horizontal: 20),
            child: Column(
              children: [
                SizedBox(height: 15),
                Hidable(
                    controller: scrollController,
                    wOpacity: false,
                    child: searchBox()),
                SizedBox(height: 15),
                Expanded(
                  child: GridView.count(
                    physics: BouncingScrollPhysics(),
                    crossAxisCount: 2,
                    children: [
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                      GridItem(),
                    ],
                  ),
                ),
              ],
            ),
          ),
          Positioned(
            bottom: 20,
            right: 20,
            child: Container(
              padding: EdgeInsets.symmetric(vertical: 5),
              child: ElevatedButton(
                onPressed: () {},
                style: ElevatedButton.styleFrom(
                  shape: RoundedRectangleBorder(
                    borderRadius: BorderRadius.circular(30),
                  ),
                  primary: AppStyle.iconColor,
                  minimumSize: Size(60, 60),
                  elevation: 10,
                ),
                child: Text(
                  '+',
                  style: TextStyle(color: Colors.white, fontSize: 40),
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }

  Container searchBox() {
    return Container(
      margin: EdgeInsets.symmetric(horizontal: 15),
      decoration: BoxDecoration(
        color: AppStyle.itemColor,
        borderRadius: BorderRadius.circular(20),
      ),
      child: TextField(
        decoration: InputDecoration(
          contentPadding: EdgeInsets.all(0),
          prefixIcon: Icon(
            Icons.search,
            color: Colors.grey,
            size: 20,
          ),
          prefixIconConstraints: BoxConstraints(
            maxHeight: 20,
            minWidth: 25,
          ),
          border: InputBorder.none,
          hintText: "Search",
          hintStyle: TextStyle(color: Colors.grey),
        ),
      ),
    );
  }

  AppBar buildAppBar() {
    return AppBar(
      backgroundColor: Colors.black,
      elevation: 0.0,
      title: Row(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Padding(
            padding: const EdgeInsets.symmetric(horizontal: 20),
            child: Icon(Icons.square, size: 35),
          ),
          Padding(
            padding: const EdgeInsets.symmetric(horizontal: 20),
            child: Icon(
              Icons.square,
              size: 35,
            ),
          ),
        ],
      ),
      centerTitle: true,
    );
  }
}

Answer 1

你可以检查滚动方向，不需要额外的包。

  isVisible = scrollController.position.userScrollDirection ==
          ScrollDirection.reverse;

class HomeScreen extends StatefulWidget {
  HomeScreen({Key? key}) : super(key: key);

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  bool isVisible = true;
  late final ScrollController scrollController = ScrollController()
    ..addListener(() {
      isVisible = scrollController.position.userScrollDirection ==
          ScrollDirection.reverse;

      setState(() {});
    });

  @override
  void dispose() {
    scrollController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.black,
      appBar: buildAppBar(),
      body: Stack(
        children: [
          Container(
            margin: EdgeInsets.symmetric(horizontal: 20),
            child: Column(
              children: [
                SizedBox(height: 15),
                SizedBox(height: 15),
                Expanded(
                  child: GridView.count(
                    controller: scrollController,
                    physics: BouncingScrollPhysics(),
                    crossAxisCount: 2,
                    children: [
                      ...List.generate(
                        33,
                        (index) => Container(
                          child: Center(
                            child: Text(
                              'Item $index',
                              style: TextStyle(
                                color: Colors.white,
                                fontSize: 20,
                              ),
                            ),
                          ),
                        ),
                      ),
                    ],
                  ),
                ),
              ],
            ),
          ),
          add_button(),
          AnimatedPositioned(
            top: isVisible ? -50 : 0,
            left: 0,
            right: 0,
            duration: Duration(seconds: 1),
            child: searchBox(),
          ),
        ],
      ),
    );
  }

  Positioned add_button() {
    return Positioned(
      bottom: 20,
      right: 20,
      child: Container(
        padding: EdgeInsets.symmetric(vertical: 5),
        child: ElevatedButton(
          onPressed: () {},
          style: ElevatedButton.styleFrom(
            shape: RoundedRectangleBorder(
              borderRadius: BorderRadius.circular(30),
            ),
            // primary: AppStyle.iconColor,
            minimumSize: Size(60, 60),
            elevation: 10,
          ),
          child: Text(
            '+',
            style: TextStyle(color: Colors.white, fontSize: 40),
          ),
        ),
      ),
    );
  }

  Container searchBox() {
    return Container(
      margin: EdgeInsets.symmetric(horizontal: 15),
      decoration: BoxDecoration(
        // color: AppStyle.itemColor,
        borderRadius: BorderRadius.circular(20),
      ),
      child: TextField(
        decoration: InputDecoration(
          contentPadding: EdgeInsets.all(0),
          prefixIcon: Icon(
            Icons.search,
            color: Colors.grey,
            size: 20,
          ),
          prefixIconConstraints: BoxConstraints(
            maxHeight: 20,
            minWidth: 25,
          ),
          border: InputBorder.none,
          hintText: "Search",
          hintStyle: TextStyle(color: Colors.grey),
        ),
      ),
    );
  }

  AppBar buildAppBar() {
    return AppBar(
      backgroundColor: Colors.black,
      elevation: 0.0,
      title: Row(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Padding(
            padding: const EdgeInsets.symmetric(horizontal: 20),
            child: Icon(Icons.square, size: 35),
          ),
          Padding(
            padding: const EdgeInsets.symmetric(horizontal: 20),
            child: Icon(
              Icons.square,
              size: 35,
            ),
          ),
        ],
      ),
      centerTitle: true,
    );
  }
}

---

只在顶部可见

  bool isVisible = true;
  late final ScrollController scrollController = ScrollController()
    ..addListener(() {
      // isVisible = scrollController.position.userScrollDirection ==
      //     ScrollDirection.reverse;

      // only visible on top
      isVisible = scrollController.offset < 100;

      setState(() {});
    });

和

AnimatedPositioned(
  top: isVisible ? 50 : -50,
  left: 0,
  right: 0,
  duration: Duration(seconds: 1),
  child: searchBox(),
),