Flutter ColorScheme类脚手架中未显示背景颜色

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它设置的黑色/紫色。我正在学习一个教程，该教程使用了简单的主题：ThemeData，但我找不到为什么我的背景颜色没有为脚手架改变的原因。

Answer 1

要为Scaffold设置背景色，可以在ThemeData中设置scaffoldBackgroundColor。

使用您的示例：

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),
),
);
}
}