flutter 侧滑删除+侧滑显示删除按钮

import 'package:flutter/material.dart';
import 'package:flutter/foundation.dart';
classDismessremove extends StatelessWidget {
  final title = '滑动删除';
  final List<String> items  =  new List<String>.generate(20, (i) => "Item ${i + 1}");
  @override
  Widget build(BuildContext context) {
    returnScaffold(
      appBar: newAppBar(
        leading: IconButton(
            icon: Icon(Icons.arrow_back),
            onPressed: () {
              Navigator.pop(context); //返回
}),
        title: newText(title),
      ),
      body: newListView.builder(
        itemCount: items.length,
        itemBuilder: (context, index) {
          final item =items[index];
          return newDismissible(
            //Each Dismissible must contain a Key. Keys allow Flutter to
            //uniquely identify Widgets.
            key: newKey(item),
            //We also need to provide a function that will tell our app
            //what to do after an item has been swiped away.
onDismissed: (direction) {
              items.removeAt(index);
              Scaffold.of(context).showSnackBar(
                  new SnackBar(content: new Text("$item dismissed")));
            },
            //Show a red background as the item is swiped away
            background: newContainer(color: Colors.red),
            child: new ListTile(title: new Text('$item'),),
          );
        },
      ),
    );
  }
}

import 'package:flutter/material.dart';
import 'package:flutter/foundation.dart';
classDismessshow extends StatefulWidget {
  @override
  _Dismessshow createState() =>_Dismessshow();
}
class _Dismessshow extends State<Dismessshow>{
  final title = '滑动显示';
//final List<String> items  =  [
//'1','2'
//];
//final List<Map> items  =  [
//{'name': 'xxx', 'show': false}
//];
  final List<Map> items = new List<Map>.generate(20, (i) {
    return {'name': 'item${i}', 'show': false};
  });
  change(index) {
    print('xxx');
  }
  @override
  Widget build(BuildContext context) {
    returnScaffold(
      appBar: newAppBar(
        leading: IconButton(
            icon: Icon(Icons.arrow_back),
            onPressed: () {
              Navigator.pop(context); //返回
}),
        title: newText(title),
      ),
      body: newListView.builder(
        itemCount: items.length,
        itemBuilder: (context, index) {
          final item =items[index];
          return newGestureDetector(
//onHorizontalDragStart:(startDetails){},
onHorizontalDragEnd: (endDetails) {
              //怎么判断方向还是个问题
setState(() {
                items[index]['show'] =
                    items[index]['show'] == true ? false : true;  //items[index]['show']!= items[index]['show'] 这样不行为啥
});
            },
            child: newContainer(
              height: 40.0,
//color: Colors.amber,
              padding: const EdgeInsets.only(left: 10.0),
              decoration: newBoxDecoration(
                  border: newBorder(
                bottom: BorderSide(color: Colors.amber,  0.5),
              )),
              child: newRow(
                children: <Widget>[
                  item['show'] == true
                      ? newRaisedButton(
                          child: new Text('remove'),
                          onPressed: () {
                            print('click');
                            setState(() {
                              items.removeAt(index);
                            });
                            Scaffold.of(context).showSnackBar(
                                new SnackBar(content: new Text('${item["name"]} is dismissed')));
                          },
                          color: Colors.yellow,
                          splashColor: Colors.pink[100])
                      : new Text(''),
                  new Text(item['name'])
                ],
              ),
            ),
          );
        },
      ),
    );
  }
}