flutter - Flutter Widget：将宽度设置为剩余宽度而不使用绝对数字

Question

我有以下颤振小部件。在“+”的右侧，我们仍然可以看到很多空闲的灰色空间。如何设置白框的宽度以使用所有剩余空间，而不使用绝对数字？

导入“包：颤振/material.dart”；

class QtyWidget extends StatefulWidget {
  String title;
  QtyWidget({this.title});
  @override
  _QtyWidgetState createState() => new _QtyWidgetState();
}

class _QtyWidgetState extends State<QtyWidget> {
  int _itemCount = 1;
  @override
  Widget build(BuildContext context) {

    return Container(
      padding: EdgeInsets.fromLTRB(10, 10, 10, 10),
      color: Colors.grey[200],
      child: Row(
          mainAxisAlignment: MainAxisAlignment.start,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: <Widget>[
            Container(
              width: 100,
              padding: EdgeInsets.fromLTRB(0, 0, 10, 0),
              child: Text(
                'Qty',
                style: TextStyle(
                    fontWeight: FontWeight.normal,
                    fontSize: 16,
                    color: Colors.grey[600]),
              ),
            ),
            Container(
              padding: EdgeInsets.fromLTRB(15, 0, 15, 0),
              decoration: BoxDecoration(
                  color: Colors.white,
                  border: Border.all(
                    color: Colors.amber[800],
                  ),
                  borderRadius: BorderRadius.all(Radius.circular(10))
              ),
              child: Row(
                children: <Widget>[
                  IconButton(icon: new Icon(Icons.remove),
                      onPressed: () {
                        setState(() {
                          _itemCount = _itemCount - 1 ;
                          if (_itemCount < 0) {
                            _itemCount = 1;
                          }
                        });

                      }),
                  Text(_itemCount.toString()),
                  IconButton(icon: new Icon(Icons.add),
                      onPressed: ()=>setState(()=>_itemCount++))
                ],
              ),
            ),
          ]),
    );

  }
}

标签： flutter

Answer 1

您可以在下面复制粘贴运行完整代码
您可以使用 wrap ContainerwithExpanded并Row使用MainAxisAlignment.centerandCrossAxisAlignment.center

代码片段

Expanded(
              child: Container(
                padding: EdgeInsets.fromLTRB(15, 0, 15, 0),
                decoration: BoxDecoration(
                    color: Colors.white,
                    border: Border.all(
                      color: Colors.amber[800],
                    ),
                    borderRadius: BorderRadius.all(Radius.circular(10))),
                child: Row(
                  mainAxisAlignment: MainAxisAlignment.center,
                  crossAxisAlignment: CrossAxisAlignment.center,

工作演示

完整代码

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

class QtyWidget extends StatefulWidget {
  String title;
  QtyWidget({this.title});
  @override
  _QtyWidgetState createState() => new _QtyWidgetState();
}

class _QtyWidgetState extends State<QtyWidget> {
  int _itemCount = 1;
  @override
  Widget build(BuildContext context) {
    return Container(
      padding: EdgeInsets.fromLTRB(10, 10, 10, 10),
      color: Colors.grey[200],
      child: Row(
          mainAxisAlignment: MainAxisAlignment.start,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: <Widget>[
            Container(
              width: 100,
              padding: EdgeInsets.fromLTRB(0, 0, 10, 0),
              child: Text(
                'Qty',
                style: TextStyle(
                    fontWeight: FontWeight.normal,
                    fontSize: 16,
                    color: Colors.grey[600]),
              ),
            ),
            Expanded(
              child: Container(
                padding: EdgeInsets.fromLTRB(15, 0, 15, 0),
                decoration: BoxDecoration(
                    color: Colors.white,
                    border: Border.all(
                      color: Colors.amber[800],
                    ),
                    borderRadius: BorderRadius.all(Radius.circular(10))),
                child: Row(
                  mainAxisAlignment: MainAxisAlignment.center,
                  crossAxisAlignment: CrossAxisAlignment.center,
                  children: <Widget>[
                    IconButton(
                        icon: new Icon(Icons.remove),
                        onPressed: () {
                          setState(() {
                            _itemCount = _itemCount - 1;
                            if (_itemCount < 0) {
                              _itemCount = 1;
                            }
                          });
                        }),
                    Text(_itemCount.toString()),
                    IconButton(
                        icon: new Icon(Icons.add),
                        onPressed: () => setState(() => _itemCount++))
                  ],
                ),
              ),
            ),
          ]),
    );
  }
}

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            QtyWidget(),
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}