capture value from login fields

Question

I'm facing a problem getting values ​​from the login field, I solved it, I'm using an elegant model, and I'm trying to modify it, seeing some examples I can't adapt to my problem.

main.dart file

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Login',
      theme: ThemeData(
        primaryColor: kPrimaryColor,
        scaffoldBackgroundColor: Colors.white,
      ),
      home: LoginScreen(),
    );
  }
}

my login.dart file

class LoginScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Body(),
    );
  }
}

they are in a separate file, I think it's better that way, but all the examples that I see people use practically inside a single file, the buttons are one for each file for that module

my file body.dart

class Body extends StatelessWidget {

  final TextEditingController usuarioController = TextEditingController();
  final TextEditingController _senhaController = TextEditingController();
/*  const Body({
    Key? key,
  }) : super(key: key);*/

  @override
  Widget build(BuildContext context) {
    Size size = MediaQuery.of(context).size;
    return Background(
      child: SingleChildScrollView(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              "LOGIN",
              style: TextStyle(fontWeight: FontWeight.bold),
            ),
            SizedBox(height: size.height * 0.03),
            SvgPicture.asset(
              "assets/icons/login.svg",
              height: size.height * 0.35,
            ),
            SizedBox(height: size.height * 0.03),
            RoundedInputField(
              hintText: "Seu Email",
              onChanged: (value) {},
            ),
            RoundedPasswordField(
              onChanged: (value) {},
            ),
            RoundedButton(
              text: "LOGIN",
              callbackClickLogin: () {},
            ),
            SizedBox(height: size.height * 0.03),
          ],
        ),enter code here
      ),
    );
  }
}

I saw in an example that I need to define

final TextEditingController userController = TextEditingController();

to get data from the user field,

and final TextEditingController _passwordController = TextEditingController();

to get the password values.

and this is the click-to-login button

my file button_login.dart

class RoundedButton extends StatelessWidget {
  final text of the String;
  final Function() callbackClickLogin;
  final color Color, textColor;
  constRounded Button({
    Key? key,
    necessary this.text,
    required this.callbackClickLogin,
    this.color = kPrimaryColor,
    this.textColor = Colors.white,
  }) : super(key: key);

  @overlay
  Widget Build (BuildContext context) {
    Size size = MediaQuery.of(context).size;
    return Container(
      margin: EdgeInsets.symmetric(vertical: 10),
      width: size.width * 0.8,
      child: ClipRRect(
        borderRadius: BorderRadius.circular(29),
        child: newElevatedButton(),
      ),
    );
  }

  //Used:ElevatedButton as FlatButton is deprecated.
  //Here we have to apply customizations to the Button inheriting the styleFrom

  newElevatedButton() widget {
    return HighButton(
      child: Text(
        text,
        style: TextStyle (color: textColor),
      ),
      onPressed: callbackClickLogin,
      style: ElevatedButton.styleFrom(
          primary color,
          padding: EdgeInsets.symmetric(horizontal: 40, vertical: 20),
          Text Style: Text Style(
              color: textColor, fontSize: 14, fontWeight: FontWeight.w500)
      ),
    );
  }
}

I don't know how to retrieve the values ​​when I click the login button, as I want to get the values ​​and pass them to another class in another file that will make a query via api.

I'm new to flutter.

thank you all.