Question

我在Android Studio上的Flutter中迈出的第一步。我的步骤：

下载并安装Android Studio
下载并安装Flutter和Dart
创建第一个默认应用程序

这是演示应用程序：

在此应用程序代码的注释中，我们有：

    // This is the theme of your application.
    // Try running your application with "flutter run". You'll see the
    // application has a blue toolbar. Then, without quitting the app, try
    // changing the primarySwatch below to Colors.green and then invoke
    // "hot reload"

我将Colors.blue更改为Colors.green，并且热重装工作正常，应用程序更改为绿色。但是当我尝试更改为Colors.black时出现错误：

“颜色”类型不是“材料颜色”类型的子类型。

演示应用程序的完整代码：

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Flutter Demo',
      theme: new ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or press Run > Flutter Hot Reload in IntelliJ). Notice that the
        // counter didn't reset back to zero; the application is not restarted.
        primarySwatch: Colors.black,
      ),
      home: new MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

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

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return new Scaffold(
      appBar: new AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: new Text(widget.title),
      ),
      body: new Center(
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        child: new Column(
          // Column is also layout widget. It takes a list of children and
          // arranges them vertically. By default, it sizes itself to fit its
          // children horizontally, and tries to be as tall as its parent.
          //
          // Invoke "debug paint" (press "p" in the console where you ran
          // "flutter run", or select "Toggle Debug Paint" from the Flutter tool
          // window in IntelliJ) to see the wireframe for each widget.
          //
          // Column has various properties to control how it sizes itself and
          // how it positions its children. Here we use mainAxisAlignment to
          // center the children vertically; the main axis here is the vertical
          // axis because Columns are vertical (the cross axis would be
          // horizontal).
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            new Text(
              'You have pushed the button this many times:',
            ),
            new Text(
              '$_counter',
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: new FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: new Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

Answer 1

您不能使用Colors.black，因为它不是MaterialColor，并且primarySwatch期望使用实质性的调色板。

如果转到ThemeData的定义，则会看到以下内容：

  ///  * The primary color palette (the [primarySwatch]), chosen from
  ///    one of the swatches defined by the material design spec. This
  ///    should be one of the maps from the [Colors] class that do not
  ///    have "accent" in their name.

例如，Colors.blue的定义是：

  static const MaterialColor blue = MaterialColor(
    _bluePrimaryValue,
    <int, Color>{
       50: Color(0xFFE3F2FD),
      100: Color(0xFFBBDEFB),
      200: Color(0xFF90CAF9),
      300: Color(0xFF64B5F6),
      400: Color(0xFF42A5F5),
      500: Color(_bluePrimaryValue),
      600: Color(0xFF1E88E5),
      700: Color(0xFF1976D2),
      800: Color(0xFF1565C0),
      900: Color(0xFF0D47A1),
    },
  );
  static const int _bluePrimaryValue = 0xFF2196F3;

Colors.black的定义是：

static const Color black = Color(0xFF000000);

这就是为什么您不能在那里使用黑色的原因。出于同样的原因，您不能使用Colors.white。这两个是上述使用没有重音词的颜色的解释的例外。

如果您想要黑色，则可以创建自己的调色板：

const MaterialColor primaryBlack = MaterialColor(
  _blackPrimaryValue,
  <int, Color>{
    50: Color(0xFF000000),
    100: Color(0xFF000000),
    200: Color(0xFF000000),
    300: Color(0xFF000000),
    400: Color(0xFF000000),
    500: Color(_blackPrimaryValue),
    600: Color(0xFF000000),
    700: Color(0xFF000000),
    800: Color(0xFF000000),
    900: Color(0xFF000000),
  },
);
const int _blackPrimaryValue = 0xFF000000;

然后使用primaryBlack代替Colors.black。

您可以调整调色板中的不同颜色。

Answer 2

只需使用primaryColor: Colors.black

我没有得到整个primarySwatch cr＃^ ......

Answer 3

您也可以简单地使用主题：ThemeData.dark（）将应用程序主题更改为Dark

Answer 4

我已经使用以下代码来获取Black Color主题。

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(

        primaryColor: Colors.black,
        //primarySwatch: Colors.black,

      ),
      home: MyHomePage(title: 'Flutter First Home Page' ),
    );
  }
}

颜色代码：

内部主题数据：（theme_data.dart）

........
......

brightness ??= Brightness.light;
final bool isDark = brightness == Brightness.dark;
primarySwatch ??= Colors.blue;
primaryColor ??= isDark ? Colors.grey[900] : primarySwatch;
primaryColorBrightness ??= estimateBrightnessForColor(primaryColor);
primaryColorLight ??= isDark ? Colors.grey[500] : primarySwatch[100];
primaryColorDark ??= isDark ? Colors.black : primarySwatch[700];
final bool primaryIsDark = primaryColorBrightness == Brightness.dark;
toggleableActiveColor ??= isDark ? Colors.tealAccent[200] : (accentColor ?? primarySwatch[600]);
accentColor ??= isDark ? Colors.tealAccent[200] : primarySwatch[500];
accentColorBrightness ??= estimateBrightnessForColor(accentColor);
final bool accentIsDark = accentColorBrightness == Brightness.dark;
canvasColor ??= isDark ? Colors.grey[850] : Colors.grey[50];
scaffoldBackgroundColor ??= canvasColor;
bottomAppBarColor ??= isDark ? Colors.grey[800] : Colors.white;
cardColor ??= isDark ? Colors.grey[800] : Colors.white;
dividerColor ??= isDark ? const Color(0x1FFFFFFF) : const Color(0x1F000000);
.....
.......

输出

Answer 5

This is how I fixed it

class MainApp extends StatelessWidget {
  static Map<int, Color> color = {
    50: Color.fromRGBO(136, 14, 79, .1),
    100: Color.fromRGBO(136, 14, 79, .2),
    200: Color.fromRGBO(136, 14, 79, .3),
    300: Color.fromRGBO(136, 14, 79, .4),
    400: Color.fromRGBO(136, 14, 79, .5),
    500: Color.fromRGBO(136, 14, 79, .6),
    600: Color.fromRGBO(136, 14, 79, .7),
    700: Color.fromRGBO(136, 14, 79, .8),
    800: Color.fromRGBO(136, 14, 79, .9),
    900: Color.fromRGBO(136, 14, 79, 1),
  };
  MaterialColor primeColor = MaterialColor(0xFF337C36, color);
  MaterialColor accentColor = MaterialColor(0xFF337C36, color);
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        primarySwatch: primeColor,
        accentColor: accentColor,
      ),
    );
  }
}

Answer 6

对此我感到抱歉，但是我感到@chemamolins答案的答案不应该被接受。
也许有必要澄清一些关于颜色的关键点，导致对这些概念的误解会导致不良的设计。

关于颜色：

问题的事实是黑白不是颜色。参见：https://adobe.com/creativecloud/design/discover/is-black-a-color.html

从物理上讲，当您的眼睛看到白色时，是因为表面反射了光谱中所有颜色的叠加。
所以你不能说白色是“一种颜色”，因为它是“某些颜色”。

另一方面，当没有颜色反射时，黑色就是您所看到的。
“没有颜色”的意思是……“没有颜色”对吗？

返回Flutter：

此颜色的值应与索引500和shade500的值相同。

请参阅：https://api.flutter.dev/flutter/material/MaterialColor-class.html

因此，对于所有大于500（600 ... 900）的值，都不存在，因为没有任何事物可以比黑色更深。
这就是为什么为这样的示例创建样本是无稽之谈。

正确的解决方案：

在我看来，@ MacDonal_11提出了更清洁的解决方案

@override
Widget build(BuildContext context) {
  return MaterialApp(
    title: 'Flutter Demo',
    theme: ThemeData(
      //primarySwatch: Colors.blue,
      primaryColor: Colors.black,
      
      /**
       * ... [The rest of your config here] ...
       */
      
      visualDensity: VisualDensity.adaptivePlatformDensity,
    ),
    home: MyHomePage(title: 'Flutter Demo Home Page'),
  );
}

将颤动主题颜色更改为黑色时出错

6 个答案: