Simple example using Flutter and Firebase MLKit (OCR)

flutter_ocr.dart

import 'dart:io';
import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';
import 'package:firebase_ml_vision/firebase_ml_vision.dart';
import 'package:translator/translator.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Realtime translation',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Realtime translation'),
    );
  }
}

class HomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  HomePageState createState() => HomePageState();
}

class HomePageState extends State<HomePage> {
  
  File _pickedImage;
  bool _isImageLoaded = false;
  bool _isTextLoaded = false;
  String _text = "";

  Future pickImage() async {
    
    var tempStore = await ImagePicker.pickImage(source: ImageSource.gallery);

    setState(() {
      _pickedImage = tempStore;
      _isImageLoaded = true;
    });
  }

  Future readText() async {
    
    FirebaseVisionImage ourImage = FirebaseVisionImage.fromFile(_pickedImage);
    TextRecognizer recognizeText = FirebaseVision.instance.textRecognizer();
    VisionText readText = await recognizeText.processImage(ourImage);

    translate(readText.text);
  }

  void translate(String readText) async {
    GoogleTranslator translator = GoogleTranslator();

    String input = readText;

    translator.translate(input, to: 'pt')
      .then((_translatedText) => {
          setState(() {
            _text = _translatedText;
            _isTextLoaded = true;
        });
      });
  }

  @override
  Widget build(BuildContext context) {
    
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Column(
        children: <Widget>[
          _isImageLoaded ? Center(
            child: Container(
              height: 200.0,
              width: 200.0,
              decoration: BoxDecoration(
                image: DecorationImage(
                  image: FileImage(pickedImage), fit: BoxFit.cover)
              ),
            ),
          ) : Container(),
          _isTextLoaded ? Center(
            child: Text(_text)
          ) : Container(),
          SizedBox(height: 10.0,),
          RaisedButton(
            child: Text('Choose an image'),
            onPressed: pickImage,
          ),
          SizedBox(height: 10.0,),
          RaisedButton(
            child: Text('Read Text'),
            onPressed: readText,
          ),
        ],
      )
    );
  }
}