how to work with gesture detector and how to creat

问题:

When I try to make an android status bar like a top bar in my app I use a gesture detector but I don't know how to proceed with it. How do I hide the container above and get the container while swiping like below:

How do I do something after a swipe ends and measure the swipe distance. The top bar should settle down or up and not stay in-between. How do I animate it to make it do it similar to how it is now. I tried onVerticalDrag etc but I don't have an idea how to it.

回答1:

Flutter Slivers can do that for you.

Check the following code:

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body:NestedScrollView(
          headerSliverBuilder: (BuildContext context, bool _) {
            return <Widget>[
              SliverAppBar(
                expandedHeight: 200.0,
                floating: true,
                pinned: true,
                snap: true,
                flexibleSpace: FlexibleSpaceBar(
                  centerTitle: true,
                  title: Text("Collapsing Toolbar",
                    style: TextStyle(
                      color: Colors.white,
                      fontSize: 16.0,
                    ),
                  ),
                ),
              ),
            ];
          },
          body: Center(
            child: Text("My Fancy Text"),
          ),
        ),
      ),
    );
  }
}