Modelli Flutter
Come costruire un'app di traduzione vocale AI utilizzando Flutter e Back4App

35min
Introduzione
In questo tutorial, imparerai come costruire un'app di traduzione vocale AI utilizzando Flutter come framework frontend e Back4App come servizio backend. L'app permetterà agli utenti di tradurre discorsi, testi e immagini in più lingue. Presenterà funzionalità di traduzione potenziate dall'AI, riconoscimento ottico dei caratteri (OCR) e riconoscimento vocale. Alla fine di questo tutorial, avrai costruito un'app in grado di gestire traduzioni in tempo reale e memorizzare la cronologia su Back4App per un uso futuro.
Prerequisiti
Per completare questo tutorial, avrai bisogno di:
Un account Back4App. Registrati per un account gratuito su Back4App.
Flutter SDK installato sul tuo computer locale. Segui la guida all'installazione di Flutter.
Conoscenze di base di Dart e Flutter. Se sei nuovo a Flutter, rivedi la documentazione di Flutter prima di procedere.
Un account con un fornitore di API di traduzione come Google Cloud Translation o DeepL.
Familiarità con le API REST e la programmazione asincrona in Dart.
Passo 1 — Configurare il tuo backend Back4App
In questo passaggio, configurerai un'applicazione Back4App, definirai i modelli di dati e configurerai il backend per memorizzare la cronologia delle traduzioni, le lingue e i dati degli utenti.
1.1. Crea una Nuova Applicazione su Back4App
Accedi al tuo dashboard di Back4App.
Clicca su "Crea nuova App".
Inserisci un Nome App (ad es., "Traduttore Vocale AI") e seleziona la tua Icona App.
Scegli la tua posizione del server se richiesto.
Clicca "Crea".
1.2. Recupera le Chiavi dell'Applicazione
Naviga su Impostazioni App > Sicurezza e Chiavi nel dashboard della tua app.
Annota il ID Applicazione e il Client Key. Questi saranno necessari per la configurazione dell'app Flutter.
1.3. Definisci i Tuoi Modelli di Dati
Creeremo le seguenti classi in Back4App:
Utente (predefinito)
Traduzione
Lingua
Frase
VoceDelDizionario
1.3.1. Crea la Classe Traduzione
Vai a Database > Browser.
Clicca su "Crea una classe".
Scegli "Personalizzato" e chiamalo Traduzione.
Clicca su "Crea classe".
Aggiungi le seguenti colonne a Traduzione:
utente (Pointer<_User>): Punta all'oggetto Utente.
linguaDiOrigine (String): Codice della lingua di origine.
linguaDiDestinazione (String): Codice della lingua di destinazione.
testoDiOrigine (String): Il testo originale da tradurre.
testoTradotto (String): Il testo tradotto.
tipoDiTraduzione (String): Tipo di traduzione (voce, testo, immagine).
timestamp (DateTime).
1.3.2. Crea la classe Language
Ripeti i passaggi per creare una nuova classe chiamata Language.
Aggiungi le seguenti colonne a Language:
nome (String): Il nome della lingua (ad es., "Inglese").
codice (String): Codice ISO della lingua (ad es., "en").
flagIconUrl (String): URL dell'immagine della bandiera che rappresenta la lingua.
1.3.3. Crea la classe Phrase
Crea una classe chiamata Phrase.
Aggiungi le seguenti colonne a Frase:
categoria (String): La categoria della frase (ad es., "Saluti").
linguaDiOrigine (String): Codice della lingua di origine.
linguaTarget (String): Codice della lingua target.
testoDiOrigine (String): La frase originale.
testoTradotto (String): La frase tradotta.
1.3.4. Crea la classe DictionaryEntry
Crea una classe chiamata DictionaryEntry.
Aggiungi le seguenti colonne a DictionaryEntry:
parola (String): La parola da definire.
lingua (String): La lingua della parola.
definizione (String): La definizione della parola.
esempi (Array): Frasi di esempio che utilizzano la parola.
1.4. Impostare i permessi a livello di classe
Assicurati che solo gli utenti autenticati possano accedere ai propri dati:
Per ogni classe, vai a Sicurezza > Permessi a livello di classe (CLP).
Imposta il CLP per consentire l'accesso in lettura/scrittura solo agli utenti autenticati.
Passo 2 — Inizializzare il tuo progetto Flutter
In questo passo, configurerai un progetto Flutter e lo configurerai per connettersi a Back4App.
2.1. Crea un nuovo progetto Flutter
Apri il tuo terminale e esegui:
Bash
flutter create ai_voice_translator
flutter create ai_voice_translator
﻿
Naviga nella directory del progetto:
Bash
cd ai_voice_translator
cd ai_voice_translator
﻿
2.2. Aggiungi le dipendenze richieste
Apri pubspec.yaml e aggiungi le seguenti dipendenze:
YAML
dependencies:
  flutter:
    sdk: flutter
  parse_server_sdk_flutter: ^4.0.1
  flutter_tts: ^3.3.1
  speech_to_text: ^5.3.0
  google_ml_kit: ^0.7.3
  provider: ^6.0.2
  http: ^0.13.4
dependencies:
  flutter:
    sdk: flutter
  parse_server_sdk_flutter: ^4.0.1
  flutter_tts: ^3.3.1
  speech_to_text: ^5.3.0
  google_ml_kit: ^0.7.3
  provider: ^6.0.2
  http: ^0.13.4
﻿
Esegui flutter pub get per installare i pacchetti.
2.3. Inizializza Parse nella tua app Flutter
Crea un nuovo file lib/config/back4app_config.dart:
Dart
// lib/config/back4app_config.dart
const String keyApplicationId = 'YOUR_APPLICATION_ID';
const String keyClientKey = 'YOUR_CLIENT_KEY';
const String keyParseServerUrl = 'https://parseapi.back4app.com';
// lib/config/back4app_config.dart
const String keyApplicationId = 'YOUR_APPLICATION_ID';
const String keyClientKey = 'YOUR_CLIENT_KEY';
const String keyParseServerUrl = 'https://parseapi.back4app.com';
﻿
Sostituisci 'YOUR_APPLICATION_ID' e 'YOUR_CLIENT_KEY' con le chiavi di Back4App.
In lib/main.dart, inizializza Parse:
Dart
// lib/main.dart
import 'package:flutter/material.dart';
import 'package:parse_server_sdk_flutter/parse_server_sdk.dart';
import 'config/back4app_config.dart';
import 'app.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  await Parse().initialize(
    keyApplicationId,
    keyParseServerUrl,
    clientKey: keyClientKey,
    autoSendSessionId: true,
    debug: true,
  );

  runApp(MyApp());
}
// lib/main.dart
import 'package:flutter/material.dart';
import 'package:parse_server_sdk_flutter/parse_server_sdk.dart';
import 'config/back4app_config.dart';
import 'app.dart';

void main() async {
  WidgetsFlutterBinding.ensureInitialized();

  await Parse().initialize(
    keyApplicationId,
    keyParseServerUrl,
    clientKey: keyClientKey,
    autoSendSessionId: true,
    debug: true,
  );

  runApp(MyApp());
}
﻿
Crea lib/app.dart:
Dart
// lib/app.dart
import 'package:flutter/material.dart';
import 'screens/home_screen.dart';

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'AI Voice Translator',
      theme: ThemeData(primarySwatch: Colors.blue),
      home: HomeScreen(),
    );
  }
}
// lib/app.dart
import 'package:flutter/material.dart';
import 'screens/home_screen.dart';

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'AI Voice Translator',
      theme: ThemeData(primarySwatch: Colors.blue),
      home: HomeScreen(),
    );
  }
}
﻿
Passo 3 — Implementazione della Traduzione del Testo
La prima funzionalità da implementare è la traduzione di base del testo.
3.1. Configura il Servizio di Traduzione
Crea lib/services/translation_service.dart per gestire le interazioni con un'API di traduzione (Google Cloud Translation API o DeepL).
Dart
// lib/services/translation_service.dart
import 'dart:convert';
import 'package:http/http.dart' as http;

class TranslationService {
  final String apiKey = 'YOUR_TRANSLATION_API_KEY';
  final String apiUrl = 'https://translation.googleapis.com/language/translate/v2';

  Future<String> translateText(String text, String sourceLang, String targetLang) async {
    final response = await http.post(
      Uri.parse(apiUrl),
      headers: {
        'Content-Type': 'application/json',
        'Authorization': 'Bearer $apiKey',
      },
      body: jsonEncode({
        'q': text,
        'source': sourceLang,
        'target': targetLang,
        'format': 'text',
      }),
    );

    if (response.statusCode == 200) {
      final data = jsonDecode(response.body);
      return data['data']['translations'][0]['translatedText'];
    } else {
      throw Exception('Translation failed');
    }
  }
}
// lib/services/translation_service.dart
import 'dart:convert';
import 'package:http/http.dart' as http;

class TranslationService {
  final String apiKey = 'YOUR_TRANSLATION_API_KEY';
  final String apiUrl = 'https://translation.googleapis.com/language/translate/v2';

  Future<String> translateText(String text, String sourceLang, String targetLang) async {
    final response = await http.post(
      Uri.parse(apiUrl),
      headers: {
        'Content-Type': 'application/json',
        'Authorization': 'Bearer $apiKey',
      },
      body: jsonEncode({
        'q': text,
        'source': sourceLang,
        'target': targetLang,
        'format': 'text',
      }),
    );

    if (response.statusCode == 200) {
      final data = jsonDecode(response.body);
      return data['data']['translations'][0]['translatedText'];
    } else {
      throw Exception('Translation failed');
    }
  }
}
﻿
3.2. Implementa il Modello di Lingua
Crea lib/models/language.dart per rappresentare le lingue supportate.
Dart
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
﻿
Dart
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
﻿
Dart
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
﻿
Dart
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
﻿
Dart
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
﻿
Dart
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
﻿
Dart
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
﻿
Dart
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
﻿
Dart
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
﻿
Dart
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
﻿
Dart
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
// lib/models/language.dart
class Language {
  final String name;
  final String code;
  final String flagIconUrl;

  Language({
    required this.name,
    required this.code,
    required this.flagIconUrl,
  });
}
﻿
3.3. Crea Schermata di Traduzione del Testo
Crea lib/screens/text_translation_screen.dart per gestire l'input di testo e la traduzione:
Dart
// lib/screens/text_translation_screen.dart
import 'package:flutter/material.dart';
import '../services/translation_service.dart';
import '../models/language.dart';

class TextTranslationScreen extends StatefulWidget {
  @override
  _TextTranslationScreenState createState() => _TextTranslationScreenState();
}

class _TextTranslationScreenState extends State<TextTranslationScreen> {
  final TranslationService translationService = TranslationService();
  final TextEditingController textController = TextEditingController();
  String translatedText = '';
  Language? sourceLanguage;
  Language? targetLanguage;

  Future<void> translate() async {
    if (sourceLanguage != null && targetLanguage != null) {
      final translation = await translationService.translateText(
        textController.text,
        sourceLanguage!.code,
        targetLanguage!.code,
      );
      setState(() {
        translatedText =

 translation;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Text Translation'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          children: [
            TextField(
              controller: textController,
              decoration: InputDecoration(labelText: 'Enter text to translate'),
            ),
            SizedBox(height: 10),
            // Implement language selectors here
            ElevatedButton(onPressed: translate, child: Text('Translate')),
            SizedBox(height: 20),
            Text(translatedText),
          ],
        ),
      ),
    );
  }
}
// lib/screens/text_translation_screen.dart
import 'package:flutter/material.dart';
import '../services/translation_service.dart';
import '../models/language.dart';

class TextTranslationScreen extends StatefulWidget {
  @override
  _TextTranslationScreenState createState() => _TextTranslationScreenState();
}

class _TextTranslationScreenState extends State<TextTranslationScreen> {
  final TranslationService translationService = TranslationService();
  final TextEditingController textController = TextEditingController();
  String translatedText = '';
  Language? sourceLanguage;
  Language? targetLanguage;

  Future<void> translate() async {
    if (sourceLanguage != null && targetLanguage != null) {
      final translation = await translationService.translateText(
        textController.text,
        sourceLanguage!.code,
        targetLanguage!.code,
      );
      setState(() {
        translatedText =

 translation;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Text Translation'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          children: [
            TextField(
              controller: textController,
              decoration: InputDecoration(labelText: 'Enter text to translate'),
            ),
            SizedBox(height: 10),
            // Implement language selectors here
            ElevatedButton(onPressed: translate, child: Text('Translate')),
            SizedBox(height: 20),
            Text(translatedText),
          ],
        ),
      ),
    );
  }
}
﻿
Passo 4 — Implementazione della Traduzione Vocale
In questo passo, aggiungerai la traduzione vocale integrando speech-to-text e text-to-speech funzionalità.
4.1. Configura il Riconoscimento Vocale
Crea lib/services/speech_recognition_service.dart utilizzando il speech_to_text pacchetto:
Dart
// lib/services/speech_recognition_service.dart
import 'package:speech_to_text/speech_to_text.dart' as stt;

class SpeechRecognitionService {
  final stt.SpeechToText _speech = stt.SpeechToText();

  Future<String?> listenForSpeech() async {
    bool available = await _speech.initialize();
    if (available) {
      await _speech.listen();
      return await Future.delayed(Duration(seconds: 5), () {
        _speech.stop();
        return _speech.lastRecognizedWords;
      });
    }
    return null;
  }
}
// lib/services/speech_recognition_service.dart
import 'package:speech_to_text/speech_to_text.dart' as stt;

class SpeechRecognitionService {
  final stt.SpeechToText _speech = stt.SpeechToText();

  Future<String?> listenForSpeech() async {
    bool available = await _speech.initialize();
    if (available) {
      await _speech.listen();
      return await Future.delayed(Duration(seconds: 5), () {
        _speech.stop();
        return _speech.lastRecognizedWords;
      });
    }
    return null;
  }
}
﻿
4.2. Aggiungi Text-to-Speech (TTS)
Crea lib/services/tts_service.dart utilizzando il flutter_tts pacchetto:
Dart
// lib/services/tts_service.dart
import 'package:flutter_tts/flutter_tts.dart';

class TtsService {
  final FlutterTts _flutterTts = FlutterTts();

  Future<void> speak(String text, String languageCode) async {
    await _flutterTts.setLanguage(languageCode);
    await _flutterTts.speak(text);
  }
}
// lib/services/tts_service.dart
import 'package:flutter_tts/flutter_tts.dart';

class TtsService {
  final FlutterTts _flutterTts = FlutterTts();

  Future<void> speak(String text, String languageCode) async {
    await _flutterTts.setLanguage(languageCode);
    await _flutterTts.speak(text);
  }
}
﻿
4.3. Crea Schermata di Traduzione Vocale
Crea lib/screens/voice_translation_screen.dart per gestire la traduzione vocale:
Dart
// lib/screens/voice_translation_screen.dart
import 'package:flutter/material.dart';
import '../services/speech_recognition_service.dart';
import '../services/translation_service.dart';
import '../services/tts_service.dart';

class VoiceTranslationScreen extends StatefulWidget {
  @override
  _VoiceTranslationScreenState createState() => _VoiceTranslationScreenState();
}

class _VoiceTranslationScreenState extends State<VoiceTranslationScreen> {
  final SpeechRecognitionService speechRecognitionService = SpeechRecognitionService();
  final TranslationService translationService = TranslationService();
  final TtsService ttsService = TtsService();

  String? recognizedText;
  String? translatedText;

  Future<void> translateSpeech() async {
    recognizedText = await speechRecognitionService.listenForSpeech();
    if (recognizedText != null) {
      translatedText = await translationService.translateText(
        recognizedText!,
        'en', // Hardcoded source language (English)
        'es', // Hardcoded target language (Spanish)
      );
      setState(() {});
      ttsService.speak(translatedText!, 'es');
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Voice Translation'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            if (recognizedText != null) Text('Recognized: $recognizedText'),
            if (translatedText != null) Text('Translated: $translatedText'),
            SizedBox(height: 20),
            ElevatedButton(onPressed: translateSpeech, child: Text('Start Voice Translation')),
          ],
        ),
      ),
    );
  }
}
// lib/screens/voice_translation_screen.dart
import 'package:flutter/material.dart';
import '../services/speech_recognition_service.dart';
import '../services/translation_service.dart';
import '../services/tts_service.dart';

class VoiceTranslationScreen extends StatefulWidget {
  @override
  _VoiceTranslationScreenState createState() => _VoiceTranslationScreenState();
}

class _VoiceTranslationScreenState extends State<VoiceTranslationScreen> {
  final SpeechRecognitionService speechRecognitionService = SpeechRecognitionService();
  final TranslationService translationService = TranslationService();
  final TtsService ttsService = TtsService();

  String? recognizedText;
  String? translatedText;

  Future<void> translateSpeech() async {
    recognizedText = await speechRecognitionService.listenForSpeech();
    if (recognizedText != null) {
      translatedText = await translationService.translateText(
        recognizedText!,
        'en', // Hardcoded source language (English)
        'es', // Hardcoded target language (Spanish)
      );
      setState(() {});
      ttsService.speak(translatedText!, 'es');
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Voice Translation'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            if (recognizedText != null) Text('Recognized: $recognizedText'),
            if (translatedText != null) Text('Translated: $translatedText'),
            SizedBox(height: 20),
            ElevatedButton(onPressed: translateSpeech, child: Text('Start Voice Translation')),
          ],
        ),
      ),
    );
  }
}
﻿
Passo 5 — Implementazione della Traduzione delle Immagini (OCR)
5.1. Configurare il Servizio OCR
Crea lib/services/ocr_service.dart utilizzando il google_ml_kit pacchetto:
Dart
// lib/services/ocr_service.dart
import 'package:google_ml_kit/google_ml_kit.dart';

class OcrService {
  final textRecognizer = GoogleMlKit.vision.textRecognizer();

  Future<String?> extractTextFromImage(String imagePath) async {
    final inputImage = InputImage.fromFilePath(imagePath);
    final recognizedText = await textRecognizer.processImage(inputImage);
    return recognizedText.text;
  }
}
// lib/services/ocr_service.dart
import 'package:google_ml_kit/google_ml_kit.dart';

class OcrService {
  final textRecognizer = GoogleMlKit.vision.textRecognizer();

  Future<String?> extractTextFromImage(String imagePath) async {
    final inputImage = InputImage.fromFilePath(imagePath);
    final recognizedText = await textRecognizer.processImage(inputImage);
    return recognizedText.text;
  }
}
﻿
5.2. Crea Schermata di Traduzione Immagine
Crea lib/screens/image_translation_screen.dart per gestire l'input dell'immagine e l'OCR:
Dart
// lib/screens/image_translation_screen.dart
import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';
import '../services/ocr_service.dart';
import '../services/translation_service.dart';

class ImageTranslationScreen extends StatefulWidget {
  @override
  _ImageTranslationScreenState createState() => _ImageTranslationScreenState();
}

class _ImageTranslationScreenState extends State<ImageTranslationScreen> {
  final OcrService ocrService = OcrService();
  final TranslationService translationService = TranslationService();
  String? extractedText;
  String? translatedText;

  Future<void> pickAndTranslateImage() async {
    final picker = ImagePicker();
    final pickedFile = await picker.getImage(source: ImageSource.gallery);

    if (pickedFile != null) {
      extractedText = await ocrService.extractTextFromImage(pickedFile.path);
      if (extractedText != null) {
        translatedText = await translationService.translateText(extractedText!, 'en', 'es');
        setState(() {});
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Image Translation'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            if (extractedText != null) Text('Extracted: $extractedText'),
            if (translatedText != null) Text('Translated: $translatedText'),
            SizedBox(height: 20),
            ElevatedButton(onPressed: pickAndTranslateImage, child: Text('Pick Image for Translation')),
          ],
        ),
      ),
    );
  }
}
// lib/screens/image_translation_screen.dart
import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';
import '../services/ocr_service.dart';
import '../services/translation_service.dart';

class ImageTranslationScreen extends StatefulWidget {
  @override
  _ImageTranslationScreenState createState() => _ImageTranslationScreenState();
}

class _ImageTranslationScreenState extends State<ImageTranslationScreen> {
  final OcrService ocrService = OcrService();
  final TranslationService translationService = TranslationService();
  String? extractedText;
  String? translatedText;

  Future<void> pickAndTranslateImage() async {
    final picker = ImagePicker();
    final pickedFile = await picker.getImage(source: ImageSource.gallery);

    if (pickedFile != null) {
      extractedText = await ocrService.extractTextFromImage(pickedFile.path);
      if (extractedText != null) {
        translatedText = await translationService.translateText(extractedText!, 'en', 'es');
        setState(() {});
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Image Translation'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            if (extractedText != null) Text('Extracted: $extractedText'),
            if (translatedText != null) Text('Translated: $translatedText'),
            SizedBox(height: 20),
            ElevatedButton(onPressed: pickAndTranslateImage, child: Text('Pick Image for Translation')),
          ],
        ),
      ),
    );
  }
}
﻿
Passo 6 — Cronologia Traduzioni e Libro delle Frasi
In questo passo, implementerai il salvataggio della cronologia delle traduzioni e la gestione di un libro delle frasi.
6.1. Salva Cronologia Traduzioni
Aggiorna lib/services/translation_service.dart per salvare la cronologia delle traduzioni in Back4App:
Dart
import 'package:parse_server_sdk_flutter/parse_server_sdk.dart';
import '../models/translation.dart';

class TranslationService {
  // Existing translation logic

  Future<void> saveTranslation(Translation translation) async {
    final translationObject = ParseObject('Translation')
      ..set('user', ParseUser.currentUser)
      ..set('sourceLanguage', translation.sourceLanguage)
      ..set('targetLanguage', translation.targetLanguage)
      ..set('sourceText', translation.sourceText)
      ..set('translatedText', translation.translatedText)
      ..set('translationType', translation.type);
    await translationObject.save();
  }
}
import 'package:parse_server_sdk_flutter/parse_server_sdk.dart';
import '../models/translation.dart';

class TranslationService {
  // Existing translation logic

  Future<void> saveTranslation(Translation translation) async {
    final translationObject = ParseObject('Translation')
      ..set('user', ParseUser.currentUser)
      ..set('sourceLanguage', translation.sourceLanguage)
      ..set('targetLanguage', translation.targetLanguage)
      ..set('sourceText', translation.sourceText)
      ..set('translatedText', translation.translatedText)
      ..set('translationType', translation.type);
    await translationObject.save();
  }
}
﻿
6.2. Implementare il Libro delle Frasi
Crea lib/screens/phrase_book_screen.dart per gestire frasi comuni:
Dart
// lib/screens/phrase_book_screen.dart
import 'package:flutter/material.dart';
import '../models/phrase.dart';
import '../services/phrase_service.dart';

class PhraseBookScreen extends StatelessWidget {
  final PhraseService phraseService = PhraseService();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Phrase Book'),
      ),
      body: FutureBuilder<List<Phrase>>(
        future: phraseService.fetchPhrases(),
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.waiting) {
            return Center(child: CircularProgressIndicator());
          }

          if (!snapshot.hasData || snapshot.data!.isEmpty) {
            return Center(child: Text('No phrases found.'));
          }

          return ListView.builder(
            itemCount: snapshot.data!.length,
            itemBuilder: (context, index) {
              final phrase = snapshot.data![index];
              return ListTile(
                title: Text('${phrase.sourceText} → ${phrase.translatedText}'),
                subtitle: Text('Category: ${phrase.category}'),
              );
            },
          );
        },
      ),
    );
  }
}
// lib/screens/phrase_book_screen.dart
import 'package:flutter/material.dart';
import '../models/phrase.dart';
import '../services/phrase_service.dart';

class PhraseBookScreen extends StatelessWidget {
  final PhraseService phraseService = PhraseService();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Phrase Book'),
      ),
      body: FutureBuilder<List<Phrase>>(
        future: phraseService.fetchPhrases(),
        builder: (context, snapshot) {
          if (snapshot.connectionState == ConnectionState.waiting) {
            return Center(child: CircularProgressIndicator());
          }

          if (!snapshot.hasData || snapshot.data!.isEmpty) {
            return Center(child: Text('No phrases found.'));
          }

          return ListView.builder(
            itemCount: snapshot.data!.length,
            itemBuilder: (context, index) {
              final phrase = snapshot.data![index];
              return ListTile(
                title: Text('${phrase.sourceText} → ${phrase.translatedText}'),
                subtitle: Text('Category: ${phrase.category}'),
              );
            },
          );
        },
      ),
    );
  }
}
﻿
Conclusione
Seguendo questo tutorial, hai costruito un AI Voice Translator App ricco di funzionalità con Flutter e Back4App. Hai implementato:
Traduzione di testo di base e avanzata.
Traduzione voce-a-voce utilizzando speech recognition e text-to-speech.
Traduzione immagine-a-testo utilizzando OCR.
Gestione della cronologia delle traduzioni e un libro di frasi per espressioni comuni.
Prossimi Passi
Migliora UI/UX: Migliora l'interfaccia dell'app per un'esperienza utente più fluida.
Migliora la Gestione degli Errori: Aggiungi gestione degli errori e meccanismi di fallback per i fallimenti dell'API.
Implementa la Modalità Offline: Memorizza le traduzioni comuni, le frasi e la cronologia per l'accesso offline.
Distribuisci l'App: Prepara l'app per la distribuzione su piattaforme iOS e Android.
﻿
Aggiornato 23 Jan 2025
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