Flutter 升起按钮'；设置主题数据'；s主样本属性

下面是一个带有升起按钮的干净颤振示例

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            RaisedButton(
              child: Text('test'),
              onPressed: () {},
            )
          ],
        ),
      ),
    );
  }
}

来自material_button.dart的代码段

/// The button's fill color, displayed by its [Material], while it
/// is in its default (unpressed, [enabled]) state.
///
/// The default fill color is the theme's button color, [ThemeData.buttonColor].
///
/// See also:
///
///  * [disabledColor] - the fill color of the button when the button is disabled.
final Color color;

基于以上内容，我假设RaisedButton的背景颜色为蓝色，因为buttonColor将从primarySwatch推断出来。相反，RaisedButton的背景颜色为灰色。

---

我知道我可以通过主题数据直接设置buttonColor参数，但由于源代码声明buttonColor将从primarySwatch推断，我只是好奇为什么它不起作用。我遗漏了什么？

您的答案在您引用的代码中：

buttonColor ??= isDark ? primarySwatch[600] : Colors.grey[300];

在同一个文件（）中，您可以看到

isDark

的定义如下：

final bool isDark = brightness == Brightness.dark;

---

由于您的主题未定义为“亮度.暗”按钮将默认为“颜色”

灰色[300]

，

查看以下答案：很高兴我能提供帮助。祝你好运

final bool isDark = brightness == Brightness.dark;