proxypin/lib/ui/component/chinese_font.dart

import 'package:flutter/material.dart';

class SystemChineseFont {
  const SystemChineseFont._();

  /// Chinese font family fallback, for windows
  static const List<String> windowsFontFamily = [
    'Microsoft YaHei',
  ];

  static const systemFont = "system-font";

  static bool systemFontLoaded = false;

  /// Chinese font family fallback, for most platforms
  static List<String> get fontFamilyFallback {
    return [
      systemFont,
      "sans-serif",
      ...windowsFontFamily,
    ];
  }

  /// Text style with updated fontFamilyFallback & fontVariations
  static TextStyle get textStyle {
    return const TextStyle().useSystemChineseFont();
  }

  /// Text theme with updated fontFamilyFallback & fontVariations
  static TextTheme get textTheme {
    return Typography().dense.apply(fontFamilyFallback: fontFamilyFallback);
  }
}

extension TextStyleUseSystemChineseFont on TextStyle {
  /// Add fontFamilyFallback & fontVariation to original font style
  TextStyle useSystemChineseFont() {
    return copyWith(
      fontFamilyFallback: [
        ...?fontFamilyFallback,
        ...SystemChineseFont.fontFamilyFallback,
      ],
      fontVariations: [
        ...?fontVariations,
        if (fontWeight != null) FontVariation('wght', (fontWeight!.index + 1) * 100),
      ],
    );
  }
}

extension TextThemeUseSystemChineseFont on TextTheme {
  /// Add fontFamilyFallback & fontVariation to original text theme
  TextTheme useSystemChineseFont() {
    return SystemChineseFont.textTheme.merge(this);
  }
}

extension ThemeDataUseSystemChineseFont on ThemeData {
  /// Add fontFamilyFallback & fontVariation to original theme data
  ThemeData useSystemChineseFont() {
    return copyWith(textTheme: textTheme.useSystemChineseFont());
  }
}