Add new flutter example of todo app with provider (#78)

todo_list_using_provider/lib/main.dart

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+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+
+import 'notifiers/todo_list.dart';
+import 'views/home.dart';
+
+void main() {
+  runApp(MyApp());
+}
+
+class MyApp extends StatelessWidget {
+  // This widget is the root of your application.
+  @override
+  Widget build(BuildContext context) {
+    return MaterialApp(
+      title: 'Flutter Demo',
+      theme: ThemeData(
+        primarySwatch: Colors.blue,
+        visualDensity: VisualDensity.adaptivePlatformDensity,
+      ),
+      home: ChangeNotifierProvider<TodoList>(
+        create: (context) => TodoList(),
+        child: MyHomePage(title: 'Flutter Demo Home Page'),
+      ),
+    );
+  }
+}

todo_list_using_provider/lib/models/todo.dart

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+import 'package:flutter/material.dart';
+
+class Todo extends ChangeNotifier {
+  final String id;
+  String title;
+  bool done;
+
+  Todo({@required this.id, this.title, this.done = false});
+
+
+  /// Toggles the value of the item and notify to listeners
+  void toggle() {
+    this.done = !this.done;
+    notifyListeners();
+  }
+}

todo_list_using_provider/lib/notifiers/todo_list.dart

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+import 'package:flutter/foundation.dart';
+import 'package:flutter_new_provider_todo/models/todo.dart';
+
+/// This class represents a model
+/// that notify listeners when it has some changes
+class TodoList extends ChangeNotifier {
+  List<Todo> _list = new List<Todo>();
+
+  List<Todo> get list => _list;
+
+  void add(Todo newItem) {
+    this._list.add(newItem);
+    notifyListeners();
+  }
+
+  void remove(Todo removedItem) {
+    this._list.remove(removedItem);
+    notifyListeners();
+  }
+
+  void clearDoneItems() {
+    this._list.removeWhere((Todo element) => element.done);
+    notifyListeners();
+  }
+}

todo_list_using_provider/lib/views/home.dart

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+import 'package:flutter/material.dart';
+
+import '../widgets/todo_list_wdt.dart';
+import '../widgets/add_button.dart';
+
+class MyHomePage extends StatelessWidget {
+  final String title;
+
+  const MyHomePage({Key key, this.title}) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    print('rebuilding Home View');
+
+    return Scaffold(
+      appBar: AppBar(
+        title: Text(title),
+      ),
+      body: Center(
+        child: TodoListWdt(),
+      ),
+      floatingActionButton: AddButton(),
+    );
+  }
+}

todo_list_using_provider/lib/widgets/add_button.dart

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+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+
+import '../models/todo.dart';
+import '../notifiers/todo_list.dart';
+
+class AddButton extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    final todoList = Provider.of<TodoList>(context, listen: false);
+    print('build IncrementButton');
+
+    return FloatingActionButton(
+      onPressed: () {
+        todoList.add(
+          new Todo(id: '${todoList.list.length}', title: 'tituloTodo${todoList.list.length}')
+        );
+      },
+      tooltip: 'Increment',
+      child: Icon(Icons.add),
+    );
+  }
+}

todo_list_using_provider/lib/widgets/todo_list_item_display.dart

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+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+
+import '../models/todo.dart';
+
+class TodoListItemDisplay extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    print('rebuilding Todo List Item Display');
+
+    return Consumer<Todo>(
+      builder: (context, todo, child) {
+        print('rebuilding Consumer Todo List Item Display');
+
+        return Text(
+          '${todo.title}: ${todo.done}',
+          style: TextStyle(fontSize: 16.0),
+        );
+      },
+    );
+  }
+}

todo_list_using_provider/lib/widgets/todo_list_item_toggle_button.dart

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+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+
+import '../models/todo.dart';
+
+class TodoListItemToggleButton extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    print('build Toggle Item Button');
+
+    return Consumer<Todo>(
+      builder: (context, todo, child) {
+        print('rebuilding Consumer Todo List Item Toggle Item Button');
+
+        return new RaisedButton(
+          onPressed: (){
+            todo.toggle();
+          },
+          color: todo.done ? Colors.blue : Colors.red,
+          child: new Icon(Icons.refresh, color: Colors.white70,),
+        );
+      },
+    );
+  }
+}

todo_list_using_provider/lib/widgets/todo_list_item_wdt.dart

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+import 'package:flutter/material.dart';
+
+import 'todo_list_item_display.dart';
+import 'todo_list_item_toggle_button.dart';
+
+
+class TodoListItemWdt extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    print('rebuilding ToDo List Item: ');
+
+    return new Row(
+      mainAxisAlignment: MainAxisAlignment.spaceAround,
+      children: [
+        TodoListItemDisplay(),
+        TodoListItemToggleButton(),
+      ],
+    );
+  }
+}

todo_list_using_provider/lib/widgets/todo_list_wdt.dart

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+import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+
+import '../models/todo.dart';
+import '../notifiers/todo_list.dart';
+import '../widgets/todo_list_item_wdt.dart';
+
+class TodoListWdt extends StatelessWidget {
+  @override
+  Widget build(BuildContext context) {
+    print('building Todo List Wdt');
+
+    return Consumer<TodoList>(
+      builder: (context, todoList, child) {
+        print('rebuilding Consumer Todo List Wdt');
+
+        return ListView.builder(
+          physics: BouncingScrollPhysics(),
+          itemCount: todoList.list.length,
+          itemBuilder: (context, index) {
+            return ChangeNotifierProvider<Todo>(
+                create: (context) => todoList.list[index],
+                child: new TodoListItemWdt()
+            );
+          },
+        );
+      },
+    );
+  }
+}