白天&黑天模式的颜色和图片不同，重点在于管理好颜色与图片

定义MyTheme初始化主题，并设置到MaterialApp

class ThemeHolder {
  static bool isDarkMode = false;
  static ThemeData theme;

  static void init(bool isDark) {
    isDarkMode = isDark;
    final brightness = isDarkMode ? Brightness.dark : Brightness.light;
    theme = ThemeData(brightness: brightness);
  }
}

MaterialApp(
      title: "Demo",
      home: _DemoWidget(),
      theme: ThemeHolder.theme,
      localizationsDelegates: ThemeHolder.localizationsDelegates,
      supportedLocales: ThemeHolder.supportedLocales,
    )

颜色

class ColorHolder {
  static const _colors = {
    "title": [Color(0x********), Color(0x********)],
    "subtitile": [Color(0x********), Color(0x********)],
  };

  static get title {
    return color("title");
  }

  static Color color(String key) {
    final colors = _colors[key];
    if (colors == null) {
      return Colors.black;
    }
    if (ThemeHolder.isDarkMode) {
      if (colors.length == 2) {
        return colors[1];
      } else {
        return colors[0];
      }
    } else {
      return colors[0];
    }
  }
}

TextStyle(fontSize: 20, color: ColorHolder.title)

图片

• 资源存放
  创建images和images_dark文件夹
• 资源声明

flutter:
  assets:
    - images/
    - images_dark/

• 扩展String添加imageName(): String

extension ImageNames on String {
  String imageName() {
    return ThemeHolder.isDarkMode ? 'images_dark/$this' : 'images/$this';
  }
}

• 使用

Image.asset('***.png'.imageName())