Question

我有一个ListView.builder，在每个项目中我打开一个配置文件页面

Navigator.push(
   context,
   MaterialPageRoute(
      builder: (context) => ProfileScreen(
      peerId: document['userId'],
   )),
);

问题是我有一个_shuffle()函数，该函数将所有文档随机化，当我关闭该ProfileScreen()时，整个ListView再次被随机化，并且由于失去滚动状态，使得UX非常困难。 / p>

有什么建议吗？

编辑检查过滤器的代码：

Future<QuerySnapshot> _filteredSnapshot() {
    if (countryFilter) {
      return Firestore.instance.collection('users').where('country', isEqualTo: country).getDocuments();
    } else {
      return Firestore.instance.collection('users').getDocuments();
    }
  }

FutureBuilder<QuerySnapshot>中的代码：

if (snapshot.data.documents.length > 0) {
                            print('STREAM ALERT');
                            final List<DocumentSnapshot> userList = snapshot.data.documents
                                .where((DocumentSnapshot documentSnapshot) => documentSnapshot['userid'] != id)
                                .toList();
                            List<DocumentSnapshot> userShuffle = _shuffle(userList);

                            return GridView.builder(
                              padding: EdgeInsets.all(10.0),
                              gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
                                  crossAxisCount: 2,
                                  mainAxisSpacing: 10.0,
                                  crossAxisSpacing: 10.0,
                                  childAspectRatio: 0.85),
                              itemBuilder: (context, index) {
                                return _buildItem(context, userShuffle[index]);
                              },
                              itemCount: userShuffle.length,
                            );
                          }

Answer 1

这是给您的示例代码。这可能对您有帮助。该示例包含2个文件main.dart和profile_screen.dart。我已经在main.dart中生成了随机列表，然后从main.dart中导航到profile_screen.dart并返回，该列表保持不变（不再再次生成随机数），并且滚动也保持在相同位置。

main.dart代码

import 'package:flutter/material.dart';
import './profile_screen.dart';

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

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  List<String> items = [];

  @override
  void initState() {
    _generateRandomItemsAndShuffle();
    super.initState();
  }

  _generateRandomItemsAndShuffle() {
    items = List<String>.generate(30, (int index) => "ITEM $index");
    items.shuffle();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Stack Overflow',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
        appBar: AppBar(
          title: Text('Stackoverflow'),
        ),
        body: ListView.builder(
          itemCount: items == null ? 0 : items.length,
          itemBuilder: (BuildContext context, int index) {
            return GestureDetector(
              child: ListTile(
                title: Text(items[index]),
                trailing: Icon(Icons.arrow_right),
              ),
              onTap: () {
                Navigator.push(
                  context,
                  MaterialPageRoute(
                    builder: (context) => ProfileScreen(
                      itemName: items[index],
                    ),
                  ),
                );
              },
            );
          },
        ),
      ),
    );
  }
}

profile_screen.dart的代码

import 'package:flutter/material.dart';
import 'package:flutter/material.dart';

class ProfileScreen extends StatefulWidget {
  String itemName;
  ProfileScreen({this.itemName});

  @override
  _ProfileScreenState createState() => _ProfileScreenState();
}

class _ProfileScreenState extends State<ProfileScreen> {
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('${widget.itemName}'),
      ),
      body: Center(
        child: Column(
          children: [Text('${widget.itemName}')],
        ),
      ),
    );
  }
}
class ProfileScreen extends StatefulWidget {
  String itemName;
  ProfileScreen({this.itemName});

  @override
  _ProfileScreenState createState() => _ProfileScreenState();
}

class _ProfileScreenState extends State<ProfileScreen> {
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('${widget.itemName}'),
      ),
      body: Center(
        child: Column(
          children: [Text('${widget.itemName}')],
        ),
      ),
    );
  }
}

此代码示例可以帮助您解决问题。

导航更新时颤振更新视图

1 个答案: