Flutter Learning Resources

https://docs.flutter.dev/reference/learning-resources
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A comprehensive catalog of Flutter tutorials, sample code, workshops, and recipes for developers...
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### Server Side Dart Examples

Source: https://docs.flutter.dev/reference/learning-resources

This quickstart provides examples of running Dart code on the server, showcasing server-side capabilities.

```dart
import 'package:shelf/shelf.dart' as shelf;
import 'package:shelf_router/shelf_router.dart';

Future<void> main() async {
  final app = Router()
    ..get('/', (shelf.Request request) => shelf.Response.ok('Hello, World!'))
    ..get('/about', (shelf.Request request) => shelf.Response.ok('About Page'));

  await shelf.serve(app.handler, 'localhost', 8080);
  print('Serving at http://localhost:8080');
}
```

--------------------------------

### Isolates Best Practices Example

Source: https://docs.flutter.dev/reference/learning-resources

This quickstart provides a sample application that demonstrates best practices for using isolates in Dart for concurrency.

```dart
Isolate.spawn(
  myIsolateFunction,
  message,
);
```

--------------------------------

### Package Constraint Solver Best Practices

Source: https://docs.flutter.dev/reference/learning-resources

This quickstart demonstrates best practices for publishing packages on pub.dev, focusing on the package constraint solver.

```dart
environment:
  sdk: ">=3.0.0 <4.0.0"
```

--------------------------------

### Counter App with Provider State Management

Source: https://docs.flutter.dev/reference/learning-resources

This quickstart demonstrates the starter Flutter application modified to use the Provider package for state management.

```dart
ChangeNotifierProvider(
  create: (context) => Counter(),
  child: const CounterWidget(),
)
```

--------------------------------

### Shopping App with Provider State Management

Source: https://docs.flutter.dev/reference/learning-resources

This quickstart presents a sample Flutter shopping application showcasing a state management approach using the Provider package.

```dart
ChangeNotifierProvider(
  create: (_) => CartModel(),
  child: const ShoppingApp(),
);
```

--------------------------------

### Desktop UI Features in Material and FluentUI

Source: https://docs.flutter.dev/reference/learning-resources

This quickstart demonstrates desktop-specific UI features available in both Material Design and FluentUI design systems within Flutter.

```dart
MaterialDesktopStyle(
  child: Scaffold(
    // ...
  ),
)
```

--------------------------------

### FFI: Call C Libraries from Dart

Source: https://docs.flutter.dev/reference/learning-resources

A series of simple examples demonstrating how to call C libraries from Dart using the Foreign Function Interface (FFI).

```dart
import 'dart:ffi';

final DynamicLibrary nativeLib = Platform.isAndroid
    ? DynamicLibrary.open('libmy_native_lib.so')
    : DynamicLibrary.process();

final int Function(int, int) add = nativeLib
    .lookup<NativeFunction<Int32 Function(Int32, Int32)>>('add')
    .asFunction();
```

--------------------------------

### Isolates (in a CLI) for Concurrency

Source: https://docs.flutter.dev/reference/learning-resources

Command line application examples demonstrating how to work with concurrency in Dart using isolates.

```dart
import 'dart:isolate';

void main() async {
  ReceivePort receivePort = ReceivePort();
  await Isolate.spawn(isolateEntry, receivePort.sendPort);
  
  receivePort.listen((message) {
    print('Received: $message');
  });
}

void isolateEntry(SendPort sendPort) {
  sendPort.send('Hello from isolate!');
}
```

--------------------------------

### Background Isolate Channels for Long-Lived Isolates

Source: https://docs.flutter.dev/reference/learning-resources

This quickstart demonstrates how to use long-lived isolates, often referred to as background isolates, and manage communication channels with them.

```dart
ReceivePort _port = ReceivePort();

static void callback() {
  // ... isolate logic ...
}

void startBackgroundIsolate() async {
  await Isolate.spawn(callback, _port.sendPort, paused: true);
  _port.first.then((dynamic data) {
    // Handle initial message from isolate
  });
  // ... other communication setup ...
}
```

--------------------------------

### Build a Form with Validation

Source: https://docs.flutter.dev/reference/learning-resources

This recipe guides you through the process of creating a form in Flutter and implementing input validation.

```dart
final _formKey = GlobalKey<FormState>();

Form(
  key: _formKey,
  child: Column(
    children: <Widget>[
      TextFormField(
        validator: (value) {
          if (value == null || value.isEmpty) {
            return 'Please enter some text';
          }
          return null;
        },
      ),
      // ...
    ],
  ),
)
```

--------------------------------

### Flutter Form App Example

Source: https://docs.flutter.dev/reference/learning-resources

A sample application demonstrating various types of forms and best practices for form handling in Flutter. Includes input validation and state management.

```dart
import 'package:flutter/material.dart';

class MyForm extends StatefulWidget {
  const MyForm({super.key});

  @override
  State<MyForm> createState() => _MyFormState();
}

class _MyFormState extends State<MyForm> {
  final _formKey = GlobalKey<FormState>();

  @override
  Widget build(BuildContext context) {
    return Form(
      key: _formKey,
      child: Column(
        children: <Widget>[
          TextFormField(
            validator: (value) {
              if (value == null || value.isEmpty) {
                return 'Please enter some text';
              }
              return null;
            },
          ),
          Padding(
            padding: const EdgeInsets.symmetric(vertical: 16.0),
            child: ElevatedButton(
              onPressed: () {
                if (_formKey.currentState!.validate()) {
                  // Process data
                  ScaffoldMessenger.of(context).showSnackBar(
                    const SnackBar(content: Text('Processing Data')),
                  );
                }
              },
              child: const Text('Submit'),
            ),
          )
        ],
      ),
    );
  }
}
```

--------------------------------

### Desktop Calculator Sample in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

A simple calculator sample designed to demonstrate a basic starting point for a desktop Flutter application. Focuses on UI layout and basic arithmetic operations.

```dart
import 'package:flutter/material.dart';

class CalculatorScreen extends StatefulWidget {
  const CalculatorScreen({super.key});

  @override
  State<CalculatorScreen> createState() => _CalculatorScreenState();
}

class _CalculatorScreenState extends State<CalculatorScreen> {
  String _output = '0';

  void _onPressed(String buttonText) {
    // Calculator logic here
    setState(() {
      _output = buttonText;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Desktop Calculator')),
      body: Column(
        children: [
          Expanded(child: Center(child: Text(_output, style: TextStyle(fontSize: 48)))),
          // Button grid would go here
        ],
      ),
    );
  }
}
```

--------------------------------

### Use the Device Camera in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Provides a basic example of how to access and use a device's camera within a Flutter application. This typically requires camera plugin integration.

```dart
import 'package:camera/camera.dart';

// Placeholder for camera usage
Future<void> takePicture() async {
  // Ensure camera is initialized and available
  // final cameras = await availableCameras();
  // final firstCamera = cameras.first;
  // ... camera initialization and capture logic ...
  print('Camera function called');
}
```

--------------------------------

### Code Sharing Between Flutter Client and Dart Server

Source: https://docs.flutter.dev/reference/learning-resources

This quickstart demonstrates how to share business logic between a Flutter client and a Dart server using the `package:shelf` library.

```dart
import 'package:shelf/shelf.dart' as shelf;

// Shared logic function
String getGreeting(String name) => 'Hello, $name!';

// Server handler
Future<shelf.Response> handler(shelf.Request request) async {
  final name = request.url.queryParameters['name'] ?? 'World';
  return shelf.Response.ok(getGreeting(name));
}
```

--------------------------------

### AI Todo List with Gemini API in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

A developer sample written in Flutter demonstrating how to interact with a to-do list in natural language using the Gemini API. Requires setup of the Gemini API.

```dart
import 'package:flutter/material.dart';
// Assume necessary imports for Gemini API and state management

class AiTodoList extends StatefulWidget {
  const AiTodoList({super.key});

  @override
  State<AiTodoList> createState() => _AiTodoListState();
}

class _AiTodoListState extends State<AiTodoList> {
  final TextEditingController _controller = TextEditingController();
  List<String> _todos = [];

  Future<void> _addTodoFromAi(String text) async {
    // Call Gemini API to process text and add to _todos
    print('Adding todo from AI: $text');
    setState(() {
      _todos.add(text);
    });
    _controller.clear();
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        TextField(
          controller: _controller,
          decoration: const InputDecoration(hintText: 'Enter task or ask AI'),
          onSubmitted: _addTodoFromAi, // Or use a button
        ),
        Expanded(
          child: ListView.builder(
            itemCount: _todos.length,
            itemBuilder: (context, index) => ListTile(title: Text(_todos[index])),
          ),
        )
      ],
    );
  }
}
```

--------------------------------

### Web Element Embedding in index.html

Source: https://docs.flutter.dev/reference/learning-resources

This quickstart modifies the index.html file of a Flutter app to launch within a custom hostElement, demonstrating basic embedding.

```html
<div id="flutter_target"></div>
```

--------------------------------

### Angular App with Flutter Element Embedding

Source: https://docs.flutter.dev/reference/learning-resources

This quickstart features a simple Angular application that replicates element embedding using a Flutter component.

```typescript
import { Component, ViewEncapsulation } from '@angular/core';
import '@angular/elements';

@Component({
  selector: 'app-root',
  template: '<flutter-app></flutter-app>',
  encapsulation: ViewEncapsulation.None,
})
export class AppComponent {}
```

--------------------------------

### Add Home Screen Widget to Flutter App (iOS)

Source: https://docs.flutter.dev/reference/learning-resources

This codelab guides you through adding a Home Screen widget to your Flutter app, applicable to iOS home screens, lock screens, or the today view.

```swift
func getTimeline(for configuration: INIntent, with completion: @escaping (INTimelime) -> Void) {
```

--------------------------------

### Add-to-App Recommended Approaches

Source: https://docs.flutter.dev/reference/learning-resources

This demo outlines recommended approaches for integrating Flutter into existing native applications.

```dart
FlutterEngine engine = FlutterEngine(withEntrypoint: "my_entrypoint");
engine.run();
```

--------------------------------

### Create a Command-Line App in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

A command-line application sample that demonstrates parsing command-line options and fetching data from GitHub. This is useful for utility tools.

```dart
import 'package:args/args.dart';

void main(List<String> arguments) {
  final parser = ArgParser()
    ..addOption('username', abbr: 'u', defaultsTo: 'octocat');

  final results = parser.parse(arguments);
  final username = results['username'] as String;

  print('Fetching data for user: $username');
  // Add GitHub API fetching logic here
}
```

--------------------------------

### Set Up Universal Links for iOS

Source: https://docs.flutter.dev/reference/learning-resources

This recipe provides instructions on how to set up universal links for iOS applications to handle deep linking.

```swift
func application(_ application: UIApplication, continue userActivity: NSUserActivity, restorationHandler: @escaping ([Any]?) -> Void) -> Bool {
```

--------------------------------

### Create a List with Headers and Items

Source: https://docs.flutter.dev/reference/learning-resources

This recipe explains how to create a list view that includes distinct headers followed by a series of list items.

```dart
ListView.separated(
  itemCount: items.length,
  separatorBuilder: (BuildContext context, int index) => const Divider(),
  itemBuilder: (BuildContext context, int index) {
    return ItemWidget(item: items[index]);
  },
)
```

--------------------------------

### Create a List with Spaced Items

Source: https://docs.flutter.dev/reference/learning-resources

This recipe demonstrates how to create a list view where padding is applied between individual items.

```dart
ListView.builder(
  padding: const EdgeInsets.all(8.0),
  itemCount: items.length,
  itemBuilder: (BuildContext context, int index) {
    return Container(
      height: 50,
      color: Colors.blue[100 * (index % 9)],
      child: Center(child: Text('Item ${index + 1}')),
    );
  },
)
```

--------------------------------

### Navigation and Routing with go_router in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

A sample demonstrating how to use the `go_router` API to handle common navigation scenarios, including deep linking and declarative routing.

```dart
import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';

final GoRouter router = GoRouter(
  routes: [
    GoRoute(path: '/', builder: (context, state) => const HomePage()),
    GoRoute(path: '/details/:id', builder: (context, state) {
      final id = state.pathParameters['id'];
      return DetailsPage(id: id);
    }),
  ],
);

class HomePage extends StatelessWidget {
  const HomePage({super.key});
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Home Page')),
      body: Center(
        child: ElevatedButton(
          onPressed: () => context.go('/details/123'),
          child: const Text('Go to Details 123'),
        ),
      ),
    );
  }
}

class DetailsPage extends StatelessWidget {
  final String? id;
  const DetailsPage({super.key, this.id});
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Details Page $id')),
      body: Center(
        child: ElevatedButton(
          onPressed: () => context.go('/'),
          child: const Text('Go to Home'),
        ),
      ),
    );
  }
}

// Use MaterialApp.router with this router configuration.
```

--------------------------------

### Create and Customize Context Menus in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

This sample demonstrates how to create and customize cross-platform context menus, such as the text selection toolbar on mobile or the right-click menu on desktop. Requires platform-specific implementations or packages.

```dart
import 'package:flutter/material.dart';

// Example of showing a context menu on long press
Widget buildContextMenuAwareWidget(BuildContext context) {
  return GestureDetector(
    onLongPress: () {
      final RenderBox overlay = Overlay.of(context)!.context.findRenderObject()! as RenderBox;
      final Offset tapPosition = (context.findRenderObject()! as RenderBox).localToGlobal(Offset.zero);

      showMenu<String>(
        context: context,
        position: RelativeRect.fromRect সম্ভাব্য (tapPosition & const Size(40, 40), Offset.zero & overlay.size),
        items: <PopupMenuEntry<String>>[
          const PopupMenuItem<String>(value: 'Option 1', child: Text('Option 1')),
          const PopupMenuItem<String>(value: 'Option 2', child: Text('Option 2')),
        ],
      ).then((String? selectedValue) {
        if (selectedValue == null) return;
        // Handle selection
        print('Selected: $selectedValue');
      });
    },
    child: Container(
      width: 100, height: 100, color: Colors.cyan,
      child: const Center(child: Text('Long Press Me')), 
    ),
  );
}
```

--------------------------------

### Persistent Storage Architecture with SQL

Source: https://docs.flutter.dev/reference/learning-resources

This recipe details how to save complex application data to a user's device using SQL for persistent storage.

```dart
var databasePath = await getDatabasesPath();
String path = join(databasePath, 'dbs');
await deleteDatabase(path);
final database = await openDatabase(
  path,
  version: 1,
  onCreate: (db, version) async {
    await db.execute(
        'CREATE TABLE IF NOT EXISTS dogs (id INTEGER PRIMARY KEY, name TEXT, age INTEGER)');
  },
);
```

--------------------------------

### Set Up Android App Links (Deep Linking)

Source: https://docs.flutter.dev/reference/learning-resources

Configure deep linking on Android to allow your app to be opened directly from web links. This involves setting up intent filters in the AndroidManifest.xml.

```xml
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.yourapp">
    <application ...>
        <activity android:name=".MainActivity" ...>
            <intent-filter>
                <action android:name="android.intent.action.VIEW" />
                <category android:name="android.intent.category.DEFAULT" />
                <category android:name="android.intent.category.BROWSABLE" />
                <data android:scheme="https" android:host="yourdomain.com" />
            </intent-filter>
        </activity>
    </application>
</manifest>
```

--------------------------------

### Simplify ViewModel Logic with Command Pattern

Source: https://docs.flutter.dev/reference/learning-resources

This recipe explains how to implement the Command pattern to simplify ViewModel logic in Flutter applications.

```dart
class SaveCommand extends Command {
  final ViewModel viewModel;
  SaveCommand(this.viewModel);

  @override
  Future<void> execute() async {
    await viewModel.saveData();
  }
}
```

--------------------------------

### Build Transitions with Material Motion in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Learn to use the Material animations package to add pre-built transitions to a Material app. This codelab focuses on creating visually appealing transitions between screens.

```dart
import 'package:flutter/material.dart';

// Example of using a Material transition (e.g., FadeThroughTransition)
// This would typically be part of a Navigator transition setup.

// Placeholder for transition usage:
void navigateWithTransition(BuildContext context) {
  Navigator.of(context).push(
    PageRouteBuilder(
      pageBuilder: (context, animation, secondaryAnimation) => const Placeholder(),
      transitionsBuilder: (context, animation, secondaryAnimation, child) {
        return FadeTransition(opacity: animation, child: child);
      },
    ),
  );
}
```

--------------------------------

### Create and Navigate to Named Routes

Source: https://docs.flutter.dev/reference/learning-resources

This recipe explains the process of defining named routes and navigating to them within a Flutter application.

```dart
MaterialApp(
  routes: {
    '/': (context) => const HomeScreen(),
    '/details': (context) => const DetailsScreen(),
  },
);
```

--------------------------------

### Work with Tabs in Material and Cupertino

Source: https://docs.flutter.dev/reference/learning-resources

This recipe covers common patterns for working with tabs in mobile applications, adhering to Material Design or Cupertino guidelines.

```dart
DefaultTabController(
  length: 2,
  child: Scaffold(
    appBar: AppBar(
      bottom: const TabBar(
        tabs: [
          Tab(icon: Icon(Icons.directions_car)),
          Tab(icon: Icon(Icons.directions_transit)),
        ],
      ),
    ),
    body: const TabBarView(
      children:
        [
          Center(child: Text('Car Tab')),
          Center(child: Text('Transit Tab')),
        ],
    ),
  ),
);
```

--------------------------------

### Add Multiplayer Support with Cloud Firestore

Source: https://docs.flutter.dev/reference/learning-resources

This recipe demonstrates how to implement multiplayer capabilities in a Flutter game using the cloud_firestore package.

```dart
FirebaseFirestore.instance.collection('games').doc(gameId).update({'players': FieldValue.arrayUnion([playerId])});
```

--------------------------------

### Mock Dependencies in Tests with Mockito

Source: https://docs.flutter.dev/reference/learning-resources

This recipe covers the basics of mocking dependencies in Flutter tests using the Mockito package.

```dart
@GenerateMocks([MyService])
class MockMyService extends Mock implements MyService {}
```

--------------------------------

### Add a Drawer to a Screen

Source: https://docs.flutter.dev/reference/learning-resources

This recipe shows how to use the Drawer widget in combination with a Scaffold to create a layout featuring a Material Design drawer.

```dart
Scaffold(
  appBar: AppBar(title: const Text('App')),
  drawer: Drawer(
    child: ListView(
      padding: EdgeInsets.zero,
      children: const <Widget>[
        DrawerHeader(
          decoration: BoxDecoration(color: Colors.blue),
          child: Text('Drawer Header'),
        ),
        ListTile(title: Text('Item 1')),
        ListTile(title: Text('Item 2')),
      ],
    ),
  ),
  body: const Center(child: Text('Content')),
);
```

--------------------------------

### Add Achievements and Leaderboards to Game

Source: https://docs.flutter.dev/reference/learning-resources

This recipe explains how to integrate leaderboard functionality into a mobile game using the games_services package.

```dart
GamesServices.submitScore(leaderboardID, score);
```

--------------------------------

### Send an HTTP PUT Request

Source: https://docs.flutter.dev/reference/learning-resources

This recipe demonstrates how to send an HTTP PUT request to update data over the internet.

```dart
final response = await http.put(
  Uri.parse('https://jsonplaceholder.typicode.com/posts/1'),
  headers: <String, String>{
    'Content-Type': 'application/json; charset=UTF-8',
  },
  body: jsonEncode<Map<String, dynamic>>(<String, dynamic>{
    'title': 'Updated Title',
    'body': 'Updated body content.',
    'userId': 1,
  }),
);
```

--------------------------------

### Build Animated Effects in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Learn to build implicit and explicit animations, and customize navigation transition animations using the animations package and predictive back on Android. Covers various animation techniques.

```dart
import 'package:flutter/material.dart';

class AnimatedSquare extends StatefulWidget {
  const AnimatedSquare({super.key});

  @override
  State<AnimatedSquare> createState() => _AnimatedSquareState();
}

class _AnimatedSquareState extends State<AnimatedSquare> {
  double _size = 100;

  void _animate() {
    setState(() {
      _size = _size == 100 ? 200 : 100;
    });
  }

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: _animate,
      child: AnimatedContainer(
        duration: const Duration(seconds: 1),
        width: _size,
        height: _size,
        color: Colors.blue,
      ),
    );
  }
}
```

--------------------------------

### Write Widget Tests in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

An introduction to writing widget tests in Flutter. Widget tests allow you to verify that your UI widgets behave as expected in isolation.

```dart
import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';

// Assume MyWidget is a widget you want to test

void main() {
  testWidgets('MyWidget has a title and message', (WidgetTester tester) async {
    // Build our app and trigger a frame.
    await tester.pumpWidget(const MyWidget(title: 'T', message: 'M'));

    // Verify that our card has the correct title and message.
    expect(find.text('T'), findsOneWidget);
    expect(find.text('M'), findsNothing);
  });
}

class MyWidget extends StatelessWidget {
  final String title;
  final String message;

  const MyWidget({super.key, required this.title, required this.message});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text(title)),
        body: Center(child: Text(message)),
      ),
    );
  }
}
```

--------------------------------

### Tap, Drag, and Enter Text in Widget Tests

Source: https://docs.flutter.dev/reference/learning-resources

This recipe covers interacting with widgets in Flutter widget tests, including tap gestures, drag operations, and text input.

```dart
await tester.tap(find.byKey(const Key('myButton')));
await tester.drag(find.byType(Scrollable), const Offset(0, -300));
await tester.enterText(find.byType(TextField), 'Test input');
```

--------------------------------

### Simplistic Text Editor in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

This sample text editor showcases the use of TextEditingDeltas and a DeltaTextInputClient to expand and contract styled ranges of text. Useful for rich text editing.

```dart
import 'package:flutter/material.dart';

class SimpleTextEditor extends StatefulWidget {
  const SimpleTextEditor({super.key});

  @override
  State<SimpleTextEditor> createState() => _SimpleTextEditorState();
}

class _SimpleTextEditorState extends State<SimpleTextEditor> {
  final TextEditingController _controller = TextEditingController();

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return TextField(
      controller: _controller,
      decoration: const InputDecoration(hintText: 'Enter text here...'),
      // Add logic for TextEditingDeltas and DeltaTextInputClient if needed
    );
  }
}
```

--------------------------------

### Animate Widget with Physics Simulation in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Learn how to move a widget from a dragged point back to the center using a spring simulation. This creates a natural, physics-based animation effect.

```dart
import 'package:flutter/material.dart';
import 'package:flutter/physics.dart';

class PhysicsAnimationWidget extends StatefulWidget {
  const PhysicsAnimationWidget({super.key});

  @override
  State<PhysicsAnimationWidget> createState() => _PhysicsAnimationWidgetState();
}

class _PhysicsAnimationWidgetState extends State<PhysicsAnimationWidget> {
  Offset _offset = Offset.zero;
  final GlobalKey _widgetKey = GlobalKey();

  void _animateToCenter() {
    final RenderBox renderBox = _widgetKey.currentContext!.findRenderObject() as RenderBox;
    final position = renderBox.localToGlobal(Offset.zero);
    final center = Offset(MediaQuery.of(context).size.width / 2, MediaQuery.of(context).size.height / 2);
    
    setState(() {
      _offset = Offset(center.dx - position.dx - renderBox.size.width / 2, center.dy - position.dy - renderBox.size.height / 2);
    });

    // Simulate physics animation back to center
    final SpringDescription spring = SpringDescription.withDampingFromTension(tension: 100, friction: 20);
    final Simulation simulation = SpringSimulation(spring, _offset.dx, 0.0, 0.0);
    
    // This part requires an AnimationController or similar mechanism to actually animate the offset
    // For simplicity, we'll just print the intended final offset.
    print('Simulating animation to center. Target offset: (0, 0)');
  }

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onPanUpdate: (details) {
        setState(() {
          _offset += details.delta;
        });
      },
      onPanEnd: (details) => _animateToCenter(),
      child: Transform.translate(
        offset: _offset,
        child: Container(
          key: _widgetKey,
          width: 50,
          height: 50,
          color: Colors.red,
        ),
      ),
    );
  }
}
```

--------------------------------

### Use Dart Records and Patterns in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Illustrates the use of Dart 3's new records and patterns features within a Flutter application for more readable and maintainable code. Requires Dart 3 or later.

```dart
// Records example
(String, int) record = ('Hello', 123);
print(record.$1);
print(record.$2);

// Patterns example
var data = {'name': 'Alice', 'age': 30};
if (data case {'name': String name, 'age': int age}) {
  print('Name: $name, Age: $age');
}
```

--------------------------------

### Dart Extension Methods Syntax

Source: https://docs.flutter.dev/reference/learning-resources

Demonstrates Dart's extension method syntax. Extensions allow you to add new functionality to existing classes without modifying their source code.

```dart
extension StringExtensions on String {
  bool get isNullOrEmpty => this.isEmpty;

  String capitalize() {
    if (isEmpty) return this;
    return '${this[0].toUpperCase()}${substring(1)}';
  }
}

void main() {
  String message = 'hello';
  print(message.capitalize()); // Output: Hello
  print(''.isNullOrEmpty);     // Output: true
}
```

--------------------------------

### Create and Style a Text Field

Source: https://docs.flutter.dev/reference/learning-resources

This recipe explores the creation and styling of text fields in Flutter, covering various customization options.

```dart
TextField(
  decoration: InputDecoration(
    border: OutlineInputBorder(),
    labelText: 'Enter text',
  ),
);
```

--------------------------------

### Fetch Data from the Internet in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Learn to use the http package to fetch data from the internet in your Flutter application. This is a fundamental task for most dynamic apps.

```dart
import 'package:http/http.dart' as http;

Future<void> fetchData() async {
  final url = Uri.parse('https://jsonplaceholder.typicode.com/posts');
  try {
    final response = await http.get(url);
    if (response.statusCode == 200) {
      print('Data fetched successfully: ${response.body}');
    } else {
      print('Failed to fetch data. Status code: ${response.statusCode}');
    }
  } catch (e) {
    print('Error fetching data: $e');
  }
}
```

--------------------------------

### Material Structure and Layout (MDC-102)

Source: https://docs.flutter.dev/reference/learning-resources

This codelab focuses on using Material Design for structure and layout in Flutter, continuing the e-commerce app from MDC-101.

```dart
Scaffold(
  appBar: AppBar(
    title: const Text('E-commerce App'),
  ),
  body: Center(
    child: Text('Welcome!'),
  ),
);
```

--------------------------------

### Make Authenticated HTTP Requests in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Learn how to include authorization headers in HTTP requests for authentication. This is essential for accessing protected API resources.

```dart
import 'package:http/http.dart' as http;

Future<void> makeAuthenticatedRequest() async {
  final url = Uri.parse('https://api.example.com/data');
  final token = 'YOUR_AUTH_TOKEN'; // Replace with your actual token

  final response = await http.get(url, headers: {
    'Authorization': 'Bearer $token',
    'Content-Type': 'application/json; charset=UTF-8',
  });

  if (response.statusCode == 200) {
    print('Data received: ${response.body}');
  } else {
    print('Request failed. Status code: ${response.statusCode}');
  }
}
```

--------------------------------

### Pass Arguments to a Named Route

Source: https://docs.flutter.dev/reference/learning-resources

This recipe explains how to pass arguments to a named route and retrieve those arguments on the destination route.

```dart
Navigator.pushNamed(context, '/details', arguments: {'id': itemId});
```

--------------------------------

### Transform Image Color Scales and Formats in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Demonstrates how to transform image color scales and formats. This is useful for image manipulation within a Flutter application.

```dart
import 'package:flutter/material.dart';

class AssetTransformations extends StatelessWidget {
  const AssetTransformations({super.key});

  @override
  Widget build(BuildContext context) {
    return Image.network(
      'https://docs.flutter.dev/assets/images/dash/dash-fever.png',
      color: Colors.blueGrey,
      colorBlendMode: BlendMode.multiply,
    );
  }
}
```

--------------------------------

### Grid Lists with GridView Widget

Source: https://docs.flutter.dev/reference/learning-resources

This recipe explains how to create and use grid layouts in Flutter applications with the GridView widget.

```dart
GridView.count(
  crossAxisCount: 2,
  children: List.generate(10, (index) {
    return Center(
      child: Text(
        'Item $index',
        style: Theme.of(context).textTheme.headlineMedium,
      ),
    );
  }),
)
```

--------------------------------

### Material Theming with Color, Shape, Elevation, and Type in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Discover how Material Components for Flutter simplify product differentiation and brand expression through design. This codelab focuses on applying Material Theming principles.

```dart
import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Material Theming Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
        // Define other theme properties like typography, shape, elevation
      ),
      home: const MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  const MyHomePage({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Material Theming'),
      ),
      body: const Center(
        child: Text('Hello World!'),
      ),
    );
  }
}
```

--------------------------------

### Export Fonts from a Package

Source: https://docs.flutter.dev/reference/learning-resources

This recipe explains how to export and use custom fonts across multiple applications from a shared package.

```dart
flutter:
  fonts:
    - family: MyCustomFont
      fonts:
        - asset: fonts/MyCustomFont.ttf
```

--------------------------------

### Implement Offline-First Support in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Implement offline-first support for a feature in an application. This involves strategies for handling data when the device is offline and synchronizing when online.

```dart
import 'package:flutter/material.dart';

// Placeholder for offline-first implementation
class OfflineFirstFeature extends StatefulWidget {
  const OfflineFirstFeature({super.key});

  @override
  State<OfflineFirstFeature> createState() => _OfflineFirstFeatureState();
}

class _OfflineFirstFeatureState extends State<OfflineFirstFeature> {
  // State variables for offline/online status and data

  @override
  Widget build(BuildContext context) {
    return const Center(child: Text('Offline-First Feature Placeholder'));
  }
}
```

--------------------------------

### Fade In Images with Placeholder using FadeInImage

Source: https://docs.flutter.dev/reference/learning-resources

This recipe utilizes the FadeInImage widget to display a visual placeholder while an image is loading.

```dart
FadeInImage.memoryNetwork(
  placeholder: kTransparentImage,
  image: 'https://example.com/image.jpg',
);
```

--------------------------------

### Handle Scrolling in Flutter Widget Tests

Source: https://docs.flutter.dev/reference/learning-resources

Learn how to simulate and handle scrolling behavior within Flutter widget tests. This is crucial for testing scrollable widgets like ListViews.

```dart
import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';

// Assume a widget with a Scrollable is present

// Example test snippet:
// testWidgets('Scrollable widget test', (WidgetTester tester) async {
//   await tester.pumpWidget(MyScrollableWidget());
//   await tester.scrollUntilVisible(
//     find.text('Target Item'),
//     50.0, // scroll offset
//     scrollable: find.byType(Scrollable),
//   );
//   expect(find.text('Target Item'), findsOneWidget);
// });
```

--------------------------------

### Create an Expandable FAB in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Create a floating action button (FAB) that expands to reveal other action buttons. This pattern is useful for providing quick access to related actions.

```dart
import 'package:flutter/material.dart';

class ExpandableFAB extends StatefulWidget {
  const ExpandableFAB({super.key});

  @override
  State<ExpandableFAB> createState() => _ExpandableFABState();
}

class _ExpandableFABState extends State<ExpandableFAB> {
  bool _isOpen = false;

  void _toggleMenu() {
    setState(() {
      _isOpen = !_isOpen;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Column( 
      mainAxisAlignment: MainAxisAlignment.end,
      children: [
        if (_isOpen) ...[
          FloatingActionButton(onPressed: () {}, child: const Icon(Icons.star)),
          const SizedBox(height: 8),
          FloatingActionButton(onPressed: () {}, child: const Icon(Icons.favorite)),
          const SizedBox(height: 8),
        ],
        FloatingActionButton(
          onPressed: _toggleMenu,
          child: Icon(_isOpen ? Icons.close : Icons.add),
        ),
      ],
    );
  }
}
```

--------------------------------

### Save Key-Value Data in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Demonstrates how to save application data to a user's on-device key-value store using the shared_preferences package. This is suitable for small amounts of data.

```dart
import 'package:shared_preferences/shared_preferences.dart';

Future<void> saveData() async {
  final prefs = await SharedPreferences.getInstance();
  await prefs.setString('username', 'JohnDoe');
  print('Data saved');
}

Future<void> loadData() async {
  final prefs = await SharedPreferences.getInstance();
  final username = prefs.getString('username');
  print('Loaded username: $username');
}
```

--------------------------------

### Navigate to a New Screen and Back with Navigator

Source: https://docs.flutter.dev/reference/learning-resources

This recipe utilizes the Navigator widget to manage navigation between different screens or routes in a Flutter application.

```dart
Navigator.push(
  context,
  MaterialPageRoute(builder: (context) => const SecondScreen()),
);
```

--------------------------------

### Display Images from the Internet in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

To display images from a URL, use the Image.network() constructor. Ensure the image URL is valid and accessible.

```dart
Image.network('https://example.com/image.jpg')
```

--------------------------------

### Add AdMob Banner and Native Ads in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Learn to implement inline banner and native ads within a travel booking app using AdMob. This codelab focuses on integrating ads into existing app structures.

```dart
import 'package:flutter/material.dart';
// Assume AdMob related imports and setup are done elsewhere

class AdMobBannerWidget extends StatelessWidget {
  const AdMobBannerWidget({super.key});

  @override
  Widget build(BuildContext context) {
    // Placeholder for AdMob banner widget
    return Container(
      height: 50,
      color: Colors.grey,
      child: const Center(child: Text('AdMob Banner')),
    );
  }
}
```

--------------------------------

### Return Data from a Screen in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Return data from one screen to another using the Navigator.pop method. This is commonly used after a user completes an action on a secondary screen.

```dart
Navigator.pop(context, 'Data to return');
```

--------------------------------

### Check App Orientation in Widget Tests

Source: https://docs.flutter.dev/reference/learning-resources

This recipe shows how to check the current orientation of the application within widget tests.

```dart
final orientation = widget.orientation;
expect(orientation, Orientation.portrait);
```

--------------------------------

### Find Widgets in Tests with flutter_test

Source: https://docs.flutter.dev/reference/learning-resources

This recipe examines the 'find' constant provided by the flutter_test package for locating widgets during testing.

```dart
final textFinder = find.text('Hello World');
expect(textFinder, findsOneWidget);
```

--------------------------------

### Implement Swipe to Dismiss with Dismissible Widget

Source: https://docs.flutter.dev/reference/learning-resources

This recipe teaches how to implement the swipe-to-dismiss functionality using the Dismissible widget in Flutter.

```dart
Dismissible(
  key: Key(item.id.toString()),
  onDismissed: (direction) {
    // Remove the item from data source
  },
  child: ListTile(title: Text(item.name)),
)
```

--------------------------------

### Report Errors to Sentry Crash Reporting

Source: https://docs.flutter.dev/reference/learning-resources

This recipe demonstrates how to integrate Sentry for reporting errors in your Flutter application.

```dart
SentryFlutter.init(
  (options) {
    options.dsn = 'YOUR_SENTRY_DSN';
  },
  appRunner: () => runApp(const MyApp()),
);
```

--------------------------------

### Lists and Floating App Bars in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Arrange a floating app bar or navigation bar above a list. This layout pattern is common for apps with scrollable content and persistent headers.

```dart
import 'package:flutter/material.dart';

Scaffold(
  body: CustomScrollView(
    slivers: <Widget>[
      const SliverAppBar(
        title: Text('Floating App Bar'),
        floating: true,
      ),
      SliverList(
        delegate: SliverChildBuilderDelegate(
          (BuildContext context, int index) {
            return ListTile(title: Text('Item $index'));
          },
          childCount: 50,
        ),
      ),
    ],
  ),
)
```

--------------------------------

### Create Nested Navigation Flows in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Define top-level routes and routes nested below specific widgets to create complex navigation structures. This is often managed using packages like go_router.

```dart
import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';

// Define top-level routes
final GoRouter _router = GoRouter(
  routes: [
    GoRoute(
      path: '/',
      builder: (context, state) => const HomeScreen(),
      routes: <RouteBase>[
        // Nested routes
        GoRoute(
          path: 'details',
          builder: (context, state) => const DetailsScreen(),
        ),
      ],
    ),
  ],
);

class HomeScreen extends StatelessWidget {
  const HomeScreen({super.key});
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Home')), 
      body: Center(
        child: ElevatedButton(
          onPressed: () => context.go('/details'),
          child: const Text('Go to Details'),
        ),
      ),
    );
  }
}

class DetailsScreen extends StatelessWidget {
  const DetailsScreen({super.key});
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Details')), 
      body: Center(
        child: ElevatedButton(
          onPressed: () => context.go('/'),
          child: const Text('Go to Home'),
        ),
      ),
    );
  }
}

// In your MaterialApp.router:
// router: _router
```

--------------------------------

### Implement Drag-and-Drop in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Builds a drag-and-drop interaction where a UI element can be moved by the user after a long press. This utilizes GestureDetector for input handling.

```dart
import 'package:flutter/material.dart';

class DraggableWidget extends StatefulWidget {
  const DraggableWidget({super.key});

  @override
  State<DraggableWidget> createState() => _DraggableWidgetState();
}

class _DraggableWidgetState extends State<DraggableWidget> {
  Offset _offset = Offset(0, 0);

  @override
  Widget build(BuildContext context) {
    return Positioned(
      left: _offset.dx,
      top: _offset.dy,
      child: GestureDetector(
        onLongPressMoveUpdate: (details) {
          setState(() {
            _offset += details.delta;
          });
        },
        child: Container(
          width: 100,
          height: 100,
          color: Colors.blue,
        ),
      ),
    );
  }
}
```

--------------------------------

### Scrolling Parallax Effect with Cards and Images

Source: https://docs.flutter.dev/reference/learning-resources

This recipe shows how to create a parallax scrolling effect by building a list of cards with images that move at different speeds.

```dart
ListView.builder(
  itemCount: items.length,
  itemBuilder: (context, index) {
    return ParallaxWidget(item: items[index]);
  },
)
```

--------------------------------

### Animate a Widget Across Screens in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Use the Hero widget to create a smooth, animated transition for a widget as it moves from one screen to another. This enhances the user experience by visually linking related elements.

```dart
import 'package:flutter/material.dart';

// On the source screen:
// Hero(
//   tag: 'hero-tag',
//   child: Image.network('your_image_url'),
// )

// On the destination screen:
// Hero(
//   tag: 'hero-tag',
//   child: Image.network('your_image_url'),
// )
```

--------------------------------

### Display a Snackbar in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Use the ScaffoldMessenger to display a Snackbar widget, providing user feedback for actions. This is commonly used for confirmations or brief messages.

```dart
ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text('Message displayed')));
```

--------------------------------

### Add Google Maps to Flutter App

Source: https://docs.flutter.dev/reference/learning-resources

This codelab covers displaying a Google Map, retrieving data from a web service, and showing that data as markers on the map.

```dart
GoogleMap(initialCameraPosition: _kGooglePlex)
```

--------------------------------

### Add User Authentication with FirebaseUI

Source: https://docs.flutter.dev/reference/learning-resources

This codelab shows how to quickly add Firebase authentication to a Flutter app using FirebaseUI, requiring minimal code.

```dart
FirebaseUI.configure(
  emailVisible: true,
  passwordVisible: true,
  // ... other configurations
);
```

--------------------------------

### Add In-App Purchases to Flutter App

Source: https://docs.flutter.dev/reference/learning-resources

Extend a simple gaming app to offer three types of in-app purchases: consumable, non-consumable, and subscription. Requires integration with store APIs (e.g., RevenueCat or store_redirect).

```dart
import 'package:flutter/material.dart';

// Placeholder for in-app purchase logic
Future<void> purchaseConsumable() async {
  print('Attempting to purchase consumable...');
  // Add purchase logic using a plugin like revenue_cat or store_redirect
}

Future<void> purchaseNonConsumable() async {
  print('Attempting to purchase non-consumable...');
  // Add purchase logic
}

Future<void> purchaseSubscription() async {
  print('Attempting to purchase subscription...');
  // Add purchase logic
}
```

--------------------------------

### Handle Taps in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Use the GestureDetector widget to respond to fundamental user actions, such as tapping and dragging. It provides callbacks for various gestures.

```dart
import 'package:flutter/material.dart';

GestureDetector(
  onTap: () {
    print('Widget tapped!');
  },
  onLongPress: () {
    print('Widget long pressed!');
  },
  child: Container(
    width: 100,
    height: 100,
    color: Colors.green,
  ),
)
```

--------------------------------

### Send HTTP POST Request in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Send HTTP POST requests in your Flutter app using the http package. This is commonly used for submitting data to a server.

```dart
import 'package:http/http.dart' as http;
import 'dart:convert';

Future<void> postData() async {
  final url = Uri.parse('https://jsonplaceholder.typicode.com/posts');
  final response = await http.post(
    url,
    headers: <String, String>{
      'Content-Type': 'application/json; charset=UTF-8',
    },
    body: jsonEncode(<String, String>{
      'title': 'foo',
      'body': 'bar',
      'userId': '1',
    }),
  );

  if (response.statusCode == 201) {
    print('Data posted successfully: ${response.body}');
  } else {
    print('Failed to post data. Status code: ${response.statusCode}');
  }
}
```

--------------------------------

### Shift Focus to a Text Field Programmatically

Source: https://docs.flutter.dev/reference/learning-resources

This recipe demonstrates how to programmatically shift the focus to a specific text field within your Flutter application.

```dart
FocusScope.of(context).requestFocus(_focusNode);
```

--------------------------------

### Work with Long Lists in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Efficiently work with long lists of data using the ListView.builder constructor. This widget builds items lazily as they are needed, improving performance.

```dart
import 'package:flutter/material.dart';

ListView.builder(
  itemCount: 1000, // Example item count
  itemBuilder: (BuildContext context, int index) {
    return ListTile(
      title: Text('Item $index'),
    );
  },
)
```

--------------------------------

### Send HTTP DELETE Request in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Use the http package to send an HTTP DELETE request to a specified URL. Ensure the http package is added to your pubspec.yaml.

```dart
import 'package:http/http.dart' as http;

Future<void> deleteData() async {
  final url = Uri.parse('https://jsonplaceholder.typicode.com/posts/1');
  final response = await http.delete(url);

  if (response.statusCode == 200) {
    print('Data deleted successfully');
  } else {
    print('Failed to delete data. Status code: ${response.statusCode}');
  }
}
```

--------------------------------

### Error Handling with Result Objects in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Improve error handling across classes with Result objects. This pattern provides a structured way to represent success or failure outcomes of operations.

```dart
sealed class Result<T, E> {
  const Result();
  factory Result.success(T value) = Success;
  factory Result.failure(E error) = Failure;
}

class Success<T, E> extends Result<T, E> {
  final T value;
  const Success(this.value);
}

class Failure<T, E> extends Result<T, E> {
  final E error;
  const Failure(this.error);
}

// Example usage:
Result<String, String> mightFail() {
  try {
    // Some operation that might fail
    return const Result.success('Operation successful!');
  } catch (e) {
    return Result.failure('Operation failed: $e');
  }
}

void main() {
  final result = mightFail();
  switch (result) {
    case Success(value: final String message):
      print('Success: $message');
    case Failure(error: final String errorMessage):
      print('Failure: $errorMessage');
  }
}
```

--------------------------------

### Add WebView to Flutter App

Source: https://docs.flutter.dev/reference/learning-resources

Integrate a WebView widget into your Android or iOS Flutter app using the webview_flutter plugin. This allows displaying web content within your application.

```dart
import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';

// Ensure you have added the webview_flutter dependency

class WebViewScreen extends StatefulWidget {
  const WebViewScreen({super.key});

  @override
  State<WebViewScreen> createState() => _WebViewScreenState();
}

class _WebViewScreenState extends State<WebViewScreen> {
  late final WebViewController controller;

  @override
  void initState() {
    super.initState();
    controller = WebViewController()
      ..setJavaScriptMode(JavaScriptMode.unrestricted)
      ..setBackgroundColor(const Color(0x00000000))
      ..setNavigationDelegate(
        NavigationDelegate(
          onPageStarted: (String url) {},
          onPageFinished: (String url) {},
          onWebResourceError: (WebResourceError error) {},
        ),
      )
      ..loadRequest(Uri.parse('https://flutter.dev'));
  }

  @override
  Widget build(BuildContext context) {
    return WebViewWidget(controller: controller);
  }
}
```

--------------------------------

### Add Material Touch Ripples in Flutter

Source: https://docs.flutter.dev/reference/learning-resources

Use the InkWell widget to display a ripple animation effect when the user interacts with a UI element, such as tapping. This provides visual feedback for touch events.

```dart
import 'package:flutter/material.dart';

InkWell(
  onTap: () {
    print('Tapped!');
  },
  child: Container(
    padding: const EdgeInsets.all(16.0),
    color: Colors.blue,
    child: const Text('Tap Me'),
  ),
)
```
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