future_builder_sample.dart

import 'package:flutter/material.dart';
import 'package:meals_catalogue/src/domain/food/food.dart';
import 'package:meals_catalogue/src/services/FoodServices.dart';
import 'package:meals_catalogue/src/ui/detail/detail_screen.dart';
import 'package:http/http.dart' as http;

class DessertScreen extends StatefulWidget {
  @override
  _DessertScreenState createState() => _DessertScreenState();
}

class _DessertScreenState extends State<DessertScreen> {
  final List<Food> _foods = List();
  final FoodService _foodService = FoodService();
  Future<Food> futureFood;

  @override
  void initState() {
    futureFood = _foodService.getDessert(http.Client());
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return SafeArea(
      child: FutureBuilder(
        initialData: _foods,
        future: futureFood,
        builder: (context, snapshot) {
          if (snapshot.hasError) {
            Scaffold.of(context).showSnackBar(
              SnackBar(
                content: Text(snapshot.error.toString()),
              ),
            );
            return Center(
              child: Text("Something wrong"),
            );
          } else if (snapshot.connectionState == ConnectionState.done) {
            Food food = snapshot.data as Food;
            return GridView.builder(
              key: Key("grid view dessert"),
              itemCount: food.meals.length,
              itemBuilder: (BuildContext context, int index) {
                Meal meal = food.meals[index];
                return GestureDetector(
                  onTap: () {
                    Scaffold.of(context).showSnackBar(SnackBar(
                      content: Text(
                        meal.strMeal,
                      ),
                      action: SnackBarAction(
                        key: Key("snack bar action dessert " + meal.idMeal),
                        label: "Open Detail",
                        onPressed: () {
                          Navigator.push(context, MaterialPageRoute(
                            builder: (context) {
                              return DetailScreen(
                                idMeal: meal.idMeal,
                                strMealThumb: meal.strMealThumb,
                                strMeal: meal.strMeal,
                                type: "dessert",
                              );
                            },
                          ));
                        },
                      ),
                    ));
                  },
                  child: Card(
                    key: Key("card dessert " + meal.idMeal),
                    child: Stack(
                      children: <Widget>[
                        Hero(
                          tag: meal.idMeal,
                          child: Image.network(
                            meal.strMealThumb,
                            fit: BoxFit.cover,
                          ),
                        ),
                        Align(
                          alignment: Alignment.bottomCenter,
                          child: Container(
                            color: Colors.white,
                            width: double.infinity,
                            height: 40.0,
                            child: Center(
                              child: Padding(
                                padding: const EdgeInsets.only(
                                  top: 4.0,
                                  right: 12.0,
                                  bottom: 8.0,
                                  left: 12.0,
                                ),
                                child: Text(
                                  meal.strMeal,
                                  textAlign: TextAlign.center,
                                  maxLines: 2,
                                  softWrap: true,
                                ),
                              ),
                            ),
                          ),
                        ),
                      ],
                    ),
                  ),
                );
              },
              gridDelegate:
                  SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 2),
            );
          } else {
            return Center(
              child: CircularProgressIndicator(key: Key("circular progress indicator dessert")),
            );
          }
        },
      ),
    );
  }
}