颤振。如何动态更改样式

Question

您好，我是使用Flutter的新手，我的英语很糟糕，但是我需要有关动态更改小部件样式的帮助

例如，我想根据JSON字段返回的值更改文本颜色。在此示例中，文本为amberAccent [400]，但取决于我想更改为其他的JSON字段返回的结果

我可以做一个if句子吗？怎么样？谢谢

import 'dart:async';
import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;

void main() {
  runApp(new MaterialApp(
    home: new HomePage(),
  ));
}

class HomePage extends StatefulWidget {
  @override
  HomePageState createState() => new HomePageState();
}

class HomePageState extends State<HomePage> {
  List data;

  Future<String> getData() async {
    var response = await http.get(
        Uri.encodeFull("https://jsonplaceholder.typicode.com/posts"),
        headers: {"Accept": "application/json"});

    this.setState(() {
      data = JSON.decode(response.body);
    });
    print(data[1]["title"]);

    return "Success!";
  }

  @override
  void initState() {
    this.getData();
  }

  @override
Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text("Listviews"),
      ),
      body: new ListView.builder(
        itemCount: data == null ? 0 : data.length,
        itemBuilder: (BuildContext context, int index) {
          return new MyCard(
            title: new Text(data[index]["title"],
              style: new TextStyle(
                  fontSize: 25.0,color: Colors.amberAccent[400]
                ),),
            subtitle: new Text(data[index]["body"],
              style: new TextStyle(
                  fontSize: 10.0,color: Colors.pinkAccent[200]))
          );
//          return new Card(
//            child: new Text(data[index]["title"]),
//          );
        },
      ),
    );
  }
}

class MyCard extends StatelessWidget {
  MyCard({this.title, this.subtitle});

  final Widget title;
  final Widget subtitle;

  @override
  Widget build(BuildContext context) {
    return new Container(
        padding: new EdgeInsets.only(bottom: 20.0),
        child: new Card(
            child: new Container(
                padding: new EdgeInsets.all(10.0),
                child: new Column(
                    children: <Widget>[this.title, this.subtitle]))));
  }
}

Answer 1

您可以使用https://flutter.io/cookbook/design/themes/中显示的主题

new Theme(
  // Create a unique theme with "new ThemeData"
  data: new ThemeData(
    accentColor: Colors.yellow,
  ),
  child: new FloatingActionButton(
    onPressed: () {},
    child: new Icon(Icons.add),
  ),
);

或在您的示例中为accentColor: Colors.amberAccent[400]
从主题获得价值
new Container(
  color: Theme.of(context).accentColor,
  child: new Text(
    'Text with a background color',
    style: Theme.of(context).textTheme.title,
  ),
);

您可以将其与StreamBuilder' or FutureBuilder`结合使用以更新主题数据。
您还可以为Flutter提供的类未涵盖的属性构建自定义Theme和ThemeData类。