https://twitter.com/kurotyann9696/status/1116654470237081605

bug_screen.dart

import 'package:flutter/material.dart';
import 'package:porto/firebase/base_firestore.dart';
import 'package:porto/model/feature_content.dart';

class StoreScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return const _StoreScreenState();
  }
}

class _StoreScreenState extends StatelessWidget {
  const _StoreScreenState({Key key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Example'),
      ),
      body: ListView.builder(
        itemCount: 2,
        itemBuilder: (context, index) {
          switch (index) {
            case 0:
              return _createMainTitle('Feature');
            case 1:
              return _createFeatureSection(context);
            default:
              return Container();
          }
        },
      ),
    );
  }

  ListTile _createMainTitle(String title) {
    return ListTile(
      title: Text(
        title,
        style: const TextStyle(
          fontWeight: FontWeight.bold,
          fontSize: 18,
        ),
      ),
    );
  }

  Widget _createFeatureSection(BuildContext context) {
    return Container(
      height: 180,
      child: FutureBuilder<FeatureContent>(
        initialData: FeatureContent.fromMap({}),
        future: BaseFirestore.getFeatureContents(),
        builder: (context, snapshot) {
          switch (snapshot.connectionState) {
            case ConnectionState.none:
            case ConnectionState.waiting:
              return const Center(child: CircularProgressIndicator());
            default:
              if (snapshot.hasError) {
                return Center(child: Text(snapshot.error.toString()));
              }

              return ListView(
                scrollDirection: Axis.horizontal,
                children: List.generate(
                  3,
                  (index) => _createFeature(context, index, snapshot.data),
                ),
              );
          }
        },
      ),
    );
  }

  Widget _createFeature(
      BuildContext context, int index, FeatureContent content) {
    return Card(
      margin: (index == 2)
          ? const EdgeInsets.symmetric(vertical: 8, horizontal: 18)
          : const EdgeInsets.only(top: 8, left: 18, bottom: 8),
      elevation: 4,
      child: Image.network(content.imageUrl),
    );
  }
}

原因判明

• https://twitter.com/kurotyann9696/status/1117718055851712512