Question

我编写了以下简单的flutter应用程序。我试图在没有MaterialApp的情况下编写此代码。早期的方向性错误即将来临，我可以使用Directionality Widget来解决。即使不使用主题，它也会显示黑屏且无输出。请纠正错误

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

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

class MyApp extends StatefulWidget
{
  @override
  State<StatefulWidget> createState() {
    // TODO: implement createState
    return _MyAppState();
  }

}

class _MyAppState extends State<MyApp> {
  double maxbid = 0.0;

  void changeBid() {
    setState(() {
      maxbid += 10.0;
    });
  }

  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return
    Theme(
      data: Theme.of(context).copyWith(canvasColor: Colors.white,buttonColor: Colors.blue),
      child:
            Column(
              children: <Widget>[
                new Directionality(textDirection: TextDirection.ltr, child: Text("your Current bid is $maxbid",)),
                new Directionality(textDirection: TextDirection.ltr, child: FlatButton.icon(

                    onPressed: changeBid,
                    label: Text("Click to increase Bid",),
                    icon: Icon(Icons.add_circle)
                )),

              ],


            )
    );

 }
}

Answer 1

任何窗口小部件都需要Material来构建窗口小部件，因此您可以通过仅将主题窗口小部件包装为Material窗口小部件来纠正它。

@override
  Widget build(BuildContext context) {
      return Material(  //added widget
        child: Theme(
            data: Theme.of(context)

添加时不使用MaterialApp返回黑屏

1 个答案: