platform_flutter_widgetsを真似た自作ウィジェット

platform_list_view.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter_hooks/flutter_hooks.dart';
import 'package:flutter_platform_widgets/flutter_platform_widgets.dart';

class PlatformListView extends HookWidget {
  final List<Widget> children;
  final Widget header;
  final Color? backgroundColor;
  final bool hasLeading;
  final EdgeInsetsGeometry? margin;
  final EdgeInsetsGeometry? padding;

  const PlatformListView({
    super.key,
    this.children = const [],
    this.header = const SizedBox.shrink(),
    this.backgroundColor,
    this.hasLeading = true,
    this.margin,
    this.padding,
  });

  @override
  Widget build(BuildContext context) {
    final platformTarget = platform(context);
    return switch (platformTarget) {
      PlatformTarget.iOS => _buildIos(context),
      PlatformTarget.android => _buildAndroid(context),
      (_) => _buildAndroid(context),
    };
  }

  Widget _buildIos(BuildContext context) {
    return CupertinoListSection.insetGrouped(
      margin: margin,
      hasLeading: hasLeading,
      dividerMargin: 14.0,
      additionalDividerMargin: hasLeading ? null : 0.0,
      backgroundColor:
          backgroundColor ?? CupertinoColors.systemGroupedBackground,
      header: header,
      children: [
        ...children,
      ],
    );
  }

  Widget _buildAndroid(BuildContext context) {
    return ListView(
      shrinkWrap: true,
      physics: const NeverScrollableScrollPhysics(),
      padding: margin,
      children: [
        Container(
          color: backgroundColor,
          padding: const EdgeInsets.symmetric(
            horizontal: 16.0,
            vertical: 8.0,
          ),
          child: header,
        ),
        ...children,
      ],
    );
  }
}

platform_sliver_app_bar.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter_platform_widgets/flutter_platform_widgets.dart';

class PlatformSliverAppBar extends StatelessWidget {
  final Widget? title;

  /// Cupertino style only use.
  final Widget? largeTitle;

  /// Material style only use.
  final bool floating;

  /// Material style only use.
  final bool pinned;
  final Widget? leading;
  final Widget? trailing;
  // Cupertino style only use.
  final bool alwaysShowMiddle;

  const PlatformSliverAppBar({
    super.key,
    this.title,
    this.largeTitle,
    this.floating = false,
    this.pinned = false,
    this.leading,
    this.trailing,
    this.alwaysShowMiddle = true,
  });

  @override
  Widget build(BuildContext context) {
    final platformTarget = platform(context);
    return switch (platformTarget) {
      PlatformTarget.iOS => _buildIos(context),
      PlatformTarget.android => _buildAndroid(context),
      (_) => _buildAndroid(context),
    };
  }

  Widget _buildIos(BuildContext context) {
    return CupertinoSliverNavigationBar(
      largeTitle: largeTitle ?? title,
      alwaysShowMiddle: alwaysShowMiddle,
      middle: title,
      leading: leading,
      trailing: trailing,
    );
  }

  Widget _buildAndroid(BuildContext context) {
    final filteredTrailing = [trailing].whereType<Widget>().toList();
    return SliverAppBar(
      title: title,
      leading: leading,
      actions: filteredTrailing,
      floating: floating,
      pinned: pinned,
    );
  }
}

プルリクを出す際には以下の2点を直すつもり

• paddingなどのパラメタはMaterialListViewDataとCupertinoListSectionDataを経由して渡すように修正
• ドキュメントの整備
• flutter_hooksを削除してStatelessWidgetとして作成
• iOSとAndroid以外のPlatformの場合は他のPlatform Widgetに倣って、UnsupportedErrorを throwする

ウィジェット名は以下のプラグインに寄せています。
https://pub.dev/documentation/flutter_platform_widgets/latest/