android - flutter :可通过卡和 margin 关闭

Question

我正在 Flutter 中构建一个简单的 listView，其中“单元格”是具有设定边距的简单卡片。当忽略这些卡片时，“边距”会覆盖可忽略的背景，从而导致设计丑陋。我创建了一个示例应用程序来展示此问题:

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

void main() {
  runApp(MyApp());
}

// MyApp is a StatefulWidget. This allows updating the state of the
// widget when an item is removed.
class MyApp extends StatefulWidget {
  MyApp({Key key}) : super(key: key);

  @override
  MyAppState createState() {
    return MyAppState();
  }
}

class MyAppState extends State<MyApp> {
  final items = List<String>.generate(20, (i) => "Item ${i + 1}");

  @override
  Widget build(BuildContext context) {
    final title = 'Dismissing Items';

    return MaterialApp(
      title: title,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
        appBar: AppBar(
          title: Text(title),
        ),
        body: ListView.builder(
          itemCount: items.length,
          itemBuilder: (context, index) {
            final item = items[index];

            return Dismissible(
              // Each Dismissible must contain a Key. Keys allow Flutter to
              // uniquely identify widgets.
              key: Key(item),
              // Provide a function that tells the app
              // what to do after an item has been swiped away.
              onDismissed: (direction) {
                // Remove the item from the data source.
                setState(() {
                  items.removeAt(index);
                });

                // Then show a snackbar.
                Scaffold.of(context)
                    .showSnackBar(SnackBar(content: Text("$item dismissed")));
              },
              // Show a red background as the item is swiped away.
              background: Container(color: Colors.red),
              child: Card(color: Colors.blue, margin: EdgeInsets.all(9), child: ListTile(title: Text('$item'))),
            );
          },
        ),
      ),
    );
  }
}

这会在关闭时产生以下设计:

也不可能将可驳回的内容放入卡中，因为那时您不会将卡刷走。这是 Flutter 中的错误还是有更简单的解决方案？

Answer 1

首先尝试用另一个小部件包裹 Dismissible，以便保留它们周围的空间，例如使用 Padding

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.only(
        left: 16,
        right: 16,
      ),
      child: Dismissible(...),
    );
  }
}

然后我们实现 Dismissible 小部件的内部部分，添加一个在我们滑动元素时将呈现的容器，并且不要忘记呈现我们将滑动的元素本身

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: const EdgeInsets.only(
        left: 16,
        right: 16,
      ),
      child: Dismissible(
        key: ValueKey(id),
        background: Container(

        // most importantly, do not forget to give the inner container a 
        // padding to the right so that our icon does not stick to the 
        // wall of the container when swiping

          padding: const EdgeInsets.only(
            right: 16,
          ),
          color: Theme.of(context).colorScheme.error,
          alignment: Alignment.centerRight,
          child: const Icon(
            Icons.delete,
            color: Colors.white,
          ),
        ),
        child: Card(

          // also if you use a card as an element that will swipe then 
          // you need to remove its default space

          margin: const EdgeInsets.all(0),
          child: ListTile(...),
      ),
    );
  }
}

希望这有帮助!)