标签: flutter-layout

我正在使用 TextFormField 来接受密码。我已将后缀图标设置为让 IconButton 子项检测单击事件并切换 TextFormField 的模糊文本属性。iconButton 的回调函数被调用，但 TextFormField 不会被重新绘制。关于如何解决这个问题的任何想法？

static Widget buildTextFormField(String id, 
                               FormFieldValidator<String> validateField,
                               FormFieldSetter<String> saveField,
                               InputDecoration decoration,
                               EdgeInsetsGeometry paddingInfo,
                               EdgeInsetsGeometry marginInfo,
                               TextInputType keyboardType,
                               {bool obscureField:false, double width:328.0,
                                TextEditingController controller}
  ){
return Container(
  padding: paddingInfo,
  margin: marginInfo,
  width: width,
  child: TextFormField(
    key: Key(id),
    obscureText: obscureField,
    validator: validateField,
    onSaved: saveField,
    keyboardType: keyboardType,
    decoration: decoration,
    controller: controller,
  ),
);

}

InputDecoration passwordDecoration = InputDecoration(
   hintText: 'Password',
   labelText: 'Enter your password',
   suffixIcon:
      IconButton(
         icon: Icon(
            _passwordVisible ? Icons.visibility : Icons.visibility_off,
            semanticLabel: …

我正在尝试使用 SingleChildScrollView 使堆栈布局可滚动，但它不滚动。这里应该使用 SingleChildScrollView 吗？

我想我已经给出了足够的描述，让任何人都能理解我的问题。此处提供更多文本以满足 StackOverflow 提出问题的要求。为此事道歉。

这是示例代码。

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: Container(
          child: Center(
            child: LayoutBuilder(
              builder:
                  (BuildContext context, BoxConstraints viewportConstraints) {
                return SingleChildScrollView(
                  child: ConstrainedBox(
                    constraints: BoxConstraints(
                      minHeight: viewportConstraints.maxHeight,
                    ),
                    child: IntrinsicHeight(
                      child: Column(
                        children: <Widget>[
                          Container(
                            // A fixed-height child.
                            color: Colors.white,
                            height: 120.0,
                          ),
                          Expanded(
                            // A flexible child that will grow to fit the viewport but
                            // still be at least as big as necessary to fit its …

我有一个连续的图像和该图像旁边的文本。我希望该行完全展开，图像作为其大小，然后保持完整区域应由 Container 使用。

这是我的代码片段：

Row(
        children: <Widget>[
          Container(
            margin: EdgeInsets.fromLTRB(10, 50, 10, 8),
            decoration: BoxDecoration(
              color: Colors.white,
              boxShadow: [
                BoxShadow(
                  color: Color.fromARGB(100, 0, 0, 0),
                  blurRadius: 5,
                ),
              ],
            ),
            child: Row(
              mainAxisSize: MainAxisSize.max,
              children: <Widget>[
                Column(children: <Widget>[
                  Image.asset(
                    'assets/card.png',
                    height: 62,
                    width: 62,
                    fit: BoxFit.cover,
                  )
                ]),
                Container(
                  child: Text("Hello world"),
                )
              ],
            ),
          ),
        ],
      ),

我想要这样： Flutter UI

我查看了 Flutter 文档，试图找到一个事件、回调，甚至是在 FlexibleSpaceBar 折叠或展开时可以挂钩的状态。

return new FlexibleSpaceBar(
  title: new Column(
    crossAxisAlignment: CrossAxisAlignment.end,
    mainAxisAlignment: MainAxisAlignment.end,
    children: <Widget>[
        new Text(_name, style: textTheme.headline),
        new Text(_caption, style: textTheme.caption)
    ]),
  centerTitle: false,
  background: getImage());`

当 FlexibleSpaceBar 被对齐（折叠）时，我想隐藏_caption文本并只显示_name文本。当它完全展开时，我显然想同时显示_name和_caption。

我该怎么做？

我不熟悉颤振，所以我对此有些迷失。

也报道在https://github.com/flutter/flutter/issues/18567

我在 Flutter 中创建了一个扩展 AppBar 类的类，这样我就可以在需要时重用它。我的问题是如何访问有状态/无状态小部件构建上下文？

class AppBarLayout extends AppBar {

  static final AppController _appController = new AppController();

  final GlobalKey<ScaffoldState> _scaffoldKey;
  final String appBarTitle;

  AppBarLayout(this.appBarTitle,this._scaffoldKey): super(
    title: Text(appBarTitle),
      leading: IconButton(
        onPressed: () => _scaffoldKey.currentState.openDrawer(),
        iconSize: 28,
        icon: Icon(Icons.menu,color: Colors.white),
      ),
      actions: <Widget>[
        IconButton(
          onPressed: () => _appController.signOut().then((_) {
            _appController.navigateTo(context, new GoogleSignView());
          }),
          icon: Icon(Icons.account_box),
          padding: EdgeInsets.all(0.0),
          ),
      ],
  );
}

我有一个 2 列颤动数据表，线条不跨越屏幕宽度，留下大量空白。我发现了这个问题

https://github.com/flutter/flutter/issues/12775

建议将 DataTable 包装在 SizedBox.expand 小部件中，但这不起作用 RenderBox was not laid out:

SizedBox.expand(
                    child: DataTable(columns:_columns, rows:_rows),
            ),

完整的小部件

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      body:
      SingleChildScrollView(
      child: Column(
        children: [Container(Text('My Text')),
        Container(
          alignment: Alignment.topLeft,
          child: SingleChildScrollView(scrollDirection: Axis.horizontal,
            child: SizedBox.expand(
                        child: DataTable(columns:_columns, rows:_rows),
                ),
          ),
        ),
      ]))
    );
  }

目标：按下一个按钮，让它切换到另一个带有动画过渡的页面。

为此，我正在使用 AnimatedSwitcher。

下面是我的代码：

class WelcomeScreenSwitcher extends State<RandomWords>{
  Widget calledWidget;

  void switchPage(int newNumber, context) {
    if (newNumber == 1) {
      setState(() {calledWidget = welcomeScreen(context);},);
    } else if (newNumber == 2) {
      setState(() {calledWidget = learnMoreScreen(context);},);}
    }

  @override
  Widget build(BuildContext context) {
    if (calledWidget == null) {
      switchPage(1, context);
    }
    return AnimatedSwitcher(
      duration: Duration(milliseconds: 5000),
      child: calledWidget,
    );

  Widget welcomeScreen(context){
    return Scaffold({body: Column(children: [
      RaisedButton(onPressed: () {switchPage(2, context);}, child: Text('B'),),],
        );
      });
    }

  Widget learnMoreScreen(context){
    return Scaffold({body: Column(children: [
      RaisedButton(onPressed: () …

我想在显示日期选择器中将语言从英语更改为法语，请在下面找到我正在使用的代码和一个应该解决该问题的类似代码，但它使代码不适用于此部分：

              new Step(
              title: new Text("Quelle est la date de 1er immatriculation?"),
              content: Column(
                children: <Widget>[
                 Text(_datetime == null ? "Vous n'avez pas encore choisi de date" : _datetime.toString().substring(0, 10)),

                  RaisedButton(
                      child: Text('choisissez une date'),
                    onPressed: () {
                    showDatePicker(context: context,
                      locale : const Locale("fr","FR"),//this line making the code not working too
                      builder: (BuildContext context, Widget child) {
                        return Theme(
                          data: ThemeData.fallback(),
                          child: child,
                        );
                      },
                     // locale: const Locale('eu', 'FR'),
                      initialDate: DateTime.now(),
                        firstDate: DateTime(1920),
                          lastDate: DateTime(2100),
                      ).then((date) {
                      setState(() { …

当我尝试从 url 加载 pdf 时出现错误。它显示pdf的页数，但随后崩溃。

使用插件 - https://pub.dev/packages/advance_pdf_viewer

????????????????????????????????????????????????????????????????????????????????????????????????????
I/flutter (28488): ??? EXCEPTION CAUGHT BY WIDGETS LIBRARY ????????????????????????????????????????????????????????????
I/flutter (28488): The following assertion was thrown while rebuilding dirty elements:
I/flutter (28488): 'package:flutter/src/widgets/framework.dart': Failed assertion: line 4371 pos 14:
I/flutter (28488): 'owner!._debugCurrentBuildTarget == this': is not true.
I/flutter (28488):
I/flutter (28488): Either the assertion indicates an error in the framework itself, or we should provide substantially
I/flutter (28488): more information in this error message to help you determine and fix the …

在我用 command 更新我的 flutter 之后flutter pub upgrade，这个函数不再被定义，任何解决方案..