Question

我有一个带有一些TextFormField的表单，并且我想扩展最后一个TextFormField以占据屏幕的其余部分。最后一个TextFormField可以包含多行文本。

我无法实现这一目标，并且尝试了SizedBox.expand()和Expanded小部件，但没有运气。

下面是当前代码：

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(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      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> {
  final GlobalKey<FormState> _formKey = GlobalKey<FormState>();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.start,
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            Text(
              "What is this new classroom?"
            ),
            SizedBox(height: 8.0,),
            Expanded(
              child: Form(
              key: _formKey,
              child: ListView(
                padding: EdgeInsets.all(8.0),
                children: <Widget>[
                  Container(
                    padding: EdgeInsets.symmetric(vertical: 8.0),
                    child: TextFormField(
                      decoration: InputDecoration(
                        border: OutlineInputBorder(),
                        labelText: "Classroom Name",
                        hintText: "What's name of the new classroom?",
                      ),
                    )
                  ),
                  SizedBox(height: 8.0,),
                  Container(
                    padding: EdgeInsets.symmetric(vertical: 8.0),
                    child: TextFormField(
                      decoration: InputDecoration(
                        border: OutlineInputBorder(),
                        labelText: "Description",
                        hintText: "Description of the new classroom",
                      ),
                      //maxLines: 5,
                    ),
                  ),
                ]
              ),
            ),
          ),
        ],
      ),
    ),
    );
  }
}

Answer 1

我稍微修改了您的代码。但是它不起作用。请参考下面的代码。我将尝试在代码下方解释我的理解。

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(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      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> {
  final GlobalKey<FormState> _formKey = GlobalKey<FormState>();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.start,
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            Text("What is this new classroom?"),
            SizedBox(
              height: 8.0,
            ),
            Expanded(
                child: Form(
              key: _formKey,
              child: Column(children: <Widget>[
                Container(
                    padding: EdgeInsets.symmetric(vertical: 8.0),
                    child: TextFormField(
                      decoration: InputDecoration(
                        border: OutlineInputBorder(),
                        labelText: "Classroom Name",
                        hintText: "What's name of the new classroom?",
                      ),
                    )),
                SizedBox(
                  height: 8.0,
                ),
                Expanded(
                  child: Container(
                    padding: EdgeInsets.symmetric(vertical: 8.0),
                    child: TextFormField(
                      maxLines: null,
                      decoration: InputDecoration(
                        border: OutlineInputBorder(),
                        labelText: "Description",
                        hintText: "Description of the new classroom",
                      ),
                    ),
                  ),
                ),
              ]),
            )),
          ],
        ),
      ),
    );
  }
}

我用您的代码检查了该视图。 TextField内部的TextFormField不会占据屏幕的其余部分。因此，我进行了编辑，以使TextField拥有其余的屏幕。上面的代码可以做到这一点。查看检查的视图

但是有InputDecorator（它是TextField的子级）绘制边界线。在我们的例子中，它根据内容绘制边界线。

可能的解决方法可能是：

maxLines = null，它将使TextField成为内容组。但是最初的观点只会是一行。
给出固定的maxLines（为10或20），看起来好像是在占据屏幕。但这不是动态的（不会根据屏幕尺寸/屏幕方向而改变）

Answer 2

您还可以在contentPadding内使用addPostFrameCallback渲染窗口小部件后设置initState()。但是您将不得不根据以上所有小部件的位置和高度来手动计算新高度。

示例：

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(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      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> {
  final GlobalKey<FormState> _formKey = GlobalKey<FormState>();
  final _tffKey1 =
      GlobalKey();
  final _tffKey2 = GlobalKey();
  final _scaffoldKey = GlobalKey();
  final _textKey = GlobalKey();
  double _height = 0;

  //Set callback that will be called after widgets are rendered.
  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) {
      final RenderBox scaffoldKeyBox = _scaffoldKey.currentContext.findRenderObject();
      final RenderBox tffBox = _tffKey1.currentContext.findRenderObject();
      final RenderBox textBox = _textKey.currentContext.findRenderObject();
      final tffPos = tffBox.localToGlobal(Offset.zero);
      final textPos = textBox.localToGlobal(Offset.zero);

      //Calculate widget's height.
      _height = (scaffoldKeyBox.size.height -
          (tffBox.size.height + tffPos.dy) -
          (textBox.size.height + textPos.dy));

      setState(() {});
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      key: _scaffoldKey,
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Padding(
        padding: const EdgeInsets.all(8.0),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.start,
          crossAxisAlignment: CrossAxisAlignment.start,
          children: <Widget>[
            Text(
              "What is this new classroom?",
              key: _textKey,
            ),
            SizedBox(
              height: 8.0,
            ),
            Expanded(
              child: Form(
                key: _formKey,
                child:
                    ListView(padding: EdgeInsets.all(8.0), children: <Widget>[
                  Container(
                      padding: EdgeInsets.symmetric(vertical: 8.0),
                      child: TextFormField(
                        key: _tffKey1,
                        decoration: InputDecoration(
                          border: OutlineInputBorder(),
                          labelText: "Classroom Name",
                          hintText: "What's name of the new classroom?",
                        ),
                      )),
                  Container(
                    padding: EdgeInsets.symmetric(vertical: 8.0),
                    child: TextFormField(
                      key: _tffKey2,
                      decoration: InputDecoration(
                        contentPadding: EdgeInsets.only(left: 8, top: _height), // Set new height here
                        border: OutlineInputBorder(),
                        labelText: "Description",
                        hintText: "Description of the new classroom",
                      ),
                    ),
                  ),
                ]),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

Answer 3

我知道现在有点晚了，但是答案已经发布了here。您只需要以下内容

TextField(
  keyboardType: TextInputType.multiline,
  maxLines: whatever,
)

Answer 4

我找到了解决方案，也许可以帮助某人。您可以创建具有边框（如TextField）的Container或其他窗口小部件，并将其展开以填充整个屏幕，并在其上方添加Stack（堆栈）小部件，使TextField带有maxLines：null和无边框。

[EDIT]它也可以在没有Stack小部件的情况下使用。这是我的代码

Expanded(
                  child: Material(
                    borderRadius: BorderRadius.circular(10),                      
                    color: Colors.white,
                    child: TextField(                         
                      decoration: InputDecoration(
                        border: InputBorder.none,  
                        hintText: "Description",                         
                      ),
                      keyboardType: TextInputType.multiline,
                      maxLines: null,
                    ),
                  ),
                ),

Flutter展开/占用TextFormField来填充屏幕的其余部分

4 个答案: