Flutter ColorScheme class 腳手架中未顯示背景色

Question

我的代碼是：

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),
      ),
    );
  }
}

而且我不知道為什么我的應用程序的背景顏色不會變成我為其設置的黑色/紫色。 我正在關注一個使用 depricated 主題的教程：ThemeData 但我找不到我的背景顏色沒有為腳手架改變的原因。

Answer 1

要為您的Scaffold設置背景顏色，您可以在ThemeData中設置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),
      ),
    );
  }
}