将容器滑动到另一个容器中以显示或隐藏一些图标，如工具栏

Question

在容器中，你假设我有 AppBar() 女巫，我想有另一个不可见的容器，就像这个屏幕截图:

另外两个容器是不可见的，我想通过从上到下或从下到上滑动来显示它们，以改变可见或不可见的可见性

从上到下滑动显示或滑动到顶部隐藏

从底部滑动到顶部显示或滑动到底部隐藏

有什么库可以实现这个滑动动画吗？

Answer 1

---

单击箭头以显示顶部/底部容器，然后隐藏这些新容器，您可以向上/向下拖动它们或简单地触摸它们。

void main() => runApp(MaterialApp(home: HomePage()));

class HomePage extends StatefulWidget {
  @override
  _HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  static double _height = 100, _one = -_height, _two = _height;
  final double _oneFixed = -_height;
  final double _twoFixed = _height;
  Duration _duration = Duration(milliseconds: 5);
  bool _top = false, _bottom = false;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("Slide")),
      body: SizedBox(
        height: _height,
        child: Stack(
          children: <Widget>[
            Positioned(
              left: 0,
              right: 0,
              height: _height,
              child: GestureDetector(
                onVerticalDragEnd: (details) {
                  if (details.velocity.pixelsPerSecond.dy >= 0) _toggleTop();
                  else _toggleBottom();
                },
                child: _myContainer(
                  color: Colors.yellow[800],
                  text: "Old Container",
                  child1: IconButton(
                    icon: Icon(Icons.arrow_downward),
                    onPressed: _toggleTop,
                  ),
                  child2: IconButton(
                    icon: Icon(Icons.arrow_upward),
                    onPressed: _toggleBottom,
                  ),
                ),
              ),
            ),
            Positioned(
              left: 0,
              right: 0,
              top: _one,
              height: _height,
              child: GestureDetector(
                onTap: _toggleTop,
                onPanEnd: (details) => _toggleTop(),
                onPanUpdate: (details) {
                  _one += details.delta.dy;
                  if (_one >= 0) _one = 0;
                  if (_one <= _oneFixed) _one = _oneFixed;
                  setState(() {});
                },
                child: _myContainer(
                  color: _one >= _oneFixed + 1 ? Colors.red[800] : Colors.transparent,
                  text: "Upper Container",
                ),
              ),
            ),
            Positioned(
              left: 0,
              right: 0,
              top: _two,
              height: _height,
              child: GestureDetector(
                onTap: _toggleBottom,
                onPanEnd: (details) => _toggleBottom(),
                onPanUpdate: (details) {
                  _two += details.delta.dy;
                  if (_two <= 0) _two = 0;
                  if (_two >= _twoFixed) _two = _twoFixed;
                  setState(() {});
                },
                child: _myContainer(
                  color: _two <= _twoFixed - 1 ? Colors.green[800] : Colors.transparent,
                  text: "Bottom Container",
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }

  void _toggleTop() {
    _top = !_top;
    Timer.periodic(_duration, (timer) {
      if (_top) _one += 2;
      else _one -= 2;

      if (_one >= 0) {
        _one = 0;
        timer.cancel();
      }
      if (_one <= _oneFixed) {
        _one = _oneFixed;
        timer.cancel();
      }
      setState(() {});
    });
  }

  void _toggleBottom() {
    _bottom = !_bottom;
    Timer.periodic(_duration, (timer) {
      if (_bottom) _two -= 2;
      else _two += 2;

      if (_two <= 0) {
        _two = 0;
        timer.cancel();
      }
      if (_two >= _twoFixed) {
        _two = _twoFixed;
        timer.cancel();
      }
      setState(() {});
    });
  }

  Widget _myContainer({Color color, String text, Widget child1, Widget child2, Function onTap}) {
    Widget child;
    if (child1 == null || child2 == null) {
      child = Text(text, style: TextStyle(fontSize: 32, color: Colors.white, fontWeight: FontWeight.bold));
    } else {
      child = Row(
        mainAxisAlignment: MainAxisAlignment.spaceAround,
        children: <Widget>[
          child1,
          child2,
        ],
      );
    }
    return GestureDetector(
      onTap: onTap,
      child: Container(
        color: color,
        alignment: Alignment.center,
        child: child,
      ),
    );
  }
}