Question

下面是一个带有RaisedButton的干净Flutter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: () {},
            )
          ],
        ),
      ),
    );
  }
}

theme_data.dart中的片段

// Used as the default color (fill color) for RaisedButtons. Computing the
// default for ButtonThemeData for the sake of backwards compatibility.
buttonColor ??= isDark ? primarySwatch[600] : Colors.grey[300];

material_button.dart中的片段

/// 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;

基于上述内容，我假设RaisedButton的背景色为蓝色，因为buttonColor将从primarySwatch推断出来。相反，RaisedButton具有灰色背景颜色。我知道我可以直接通过ThemeData设置buttonColor参数，但是由于源代码指出buttonColor可以从primarySwatch推断出来，所以我很好奇为什么它不起作用。我想念什么？

Answer 1

您的答案在您引用的代码中：

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

在同一文件（theme_data.dart）上，您可以看到isDark被定义为：

final bool isDark = brightness == Brightness.dark;

由于您的主题未定义为Brightness.dark，因此该按钮将默认为Colors.grey[300]。

设置ThemeData的primaryswatch属性后，RaisedButton的背景色不会更改

1 个答案: