on_platform_variant.dart

class OnPlatformVariant extends ContextVariant {
  final TargetPlatform platform;

  const OnPlatformVariant(this.platform);

  @override
  bool when(BuildContext context) {
    return defaultTargetPlatform == platform;
  }

  @override
  List<Object?> get props => [platform];

  @override
  Object get mergeKey => '$runtimeType.${platform.name}';
}

class OnWebVariant extends ContextVariant {
  const OnWebVariant();

  @override
  bool when(_) => kIsWeb;
}


extension OnContextVariantUtilityX on OnContextVariantUtility {
  OnPlatformVariant onPlatform(TargetPlatform platform) {
    return OnPlatformVariant(platform);
  }

  OnPlatformVariant get android => OnPlatformVariant(TargetPlatform.android);
  OnPlatformVariant get fuchsia => OnPlatformVariant(TargetPlatform.fuchsia);
  OnPlatformVariant get ios => OnPlatformVariant(TargetPlatform.iOS);
  OnPlatformVariant get linux => OnPlatformVariant(TargetPlatform.linux);
  OnPlatformVariant get macos => OnPlatformVariant(TargetPlatform.macOS);
  OnPlatformVariant get windows => OnPlatformVariant(TargetPlatform.windows);
  OnWebVariant get web => OnWebVariant();
}