Flutter ColorScheme 类背景颜色未显示在脚手架中

Question

我的代码是：

import 'package:flutter/material.dart';

void main() => runApp(BMICalculator());

class BMICalculator extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final ThemeData theme = ThemeData();

    return MaterialApp(
      theme: theme.copyWith(
        colorScheme: theme.colorScheme.copyWith(
          secondary: Colors.purple,
          primary: Color(0xFF0d0f1e),
          background: primaryC,
        ),
      ),
      home: InputPage(),
    );
  }
}

class InputPage extends StatefulWidget {
  @override
  _InputPageState createState() => _InputPageState();
}

class _InputPageState extends State<InputPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('BMI CALCULATOR'),
      ),
      body: Center(
        child: Text('Body Text'),
      ),
      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.add),
      ),
    );
  }
}

我不知道为什么我的应用程序的背景颜色不会变成我为其设置的黑色/紫色。我正在遵循一个使用已废弃主题的教程：ThemeData，但我找不到我的背景颜色没有针对脚手架发生变化的原因。

Answer 1

要为 Scaffold 设置背景颜色，您可以设置 ThemeData 中的scaffoldBackgroundColor。

使用你的例子：

import 'package:flutter/material.dart';

void main() => runApp(BMICalculator());

class BMICalculator extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final ThemeData theme = ThemeData();

    return MaterialApp(
      theme: theme.copyWith(
        // Pick the color here
        scaffoldBackgroundColor: Colors.black,
        colorScheme: theme.colorScheme.copyWith(
          secondary: Colors.purple,
          primary: Color(0xFF0d0f1e),
        ),
      ),
      home: InputPage(),
    );
  }
}

class InputPage extends StatefulWidget {
  @override
  _InputPageState createState() => _InputPageState();
}

class _InputPageState extends State<InputPage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('BMI CALCULATOR'),
      ),
      body: Center(
        child: Text('Body Text'),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {},
        child: Icon(Icons.add),
      ),
    );
  }
}