google_translate.dart

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


void main()
{
  runApp(
      MaterialApp(
        theme: ThemeData(
          primaryColor: Colors.red[500],
        ),
        home: App(),
      )
  );

}

class App extends StatefulWidget {
  @override
  _AppState createState() => _AppState();
}

class _AppState extends State<App> {

  GoogleTranslator translator = new GoogleTranslator();


  String out;
  final lang=TextEditingController();


  void trans()
  {

    translator.translate(lang.text, to: 'fr')
        .then((output)
    {
      setState(() {
        out=output;
      });
      print(out);
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("Google Transalate"),
      ),
      body: Container(
        child: Center(
              child: Column(
                children: <Widget>[
                  Card(
                    child: Padding(
                      padding: const EdgeInsets.all(8.0),
                      child: Row(
                        mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                        children: <Widget>[
                          Text("English",style: TextStyle(fontSize: 17,color: Colors.red),),
                          Icon(Icons.swap_horiz),
                          Text("French",style: TextStyle(fontSize: 17,color: Colors.red),),

                        ],
                      ),
                    ),
                  ),

                  Padding(
                    padding: const EdgeInsets.only(left:10.0,right: 10),
                    child: TextField(
                      controller: lang,
                    ),
                  ),
                  MaterialButton(
                    shape: RoundedRectangleBorder(
                      borderRadius: BorderRadius.circular(12),
                    ),
                    color: Colors.orange,
                    child: Text("Press "),
                    onPressed: ()
                    {
                      trans();
                    },
                  ),
                  SizedBox(height: 10,),
                  Text(out.toString(),style: TextStyle(fontSize: 18),)
                ],
              ),

        ),
      ),
    );
  }
}