jokenpo flutter

Jogo.dart

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

class Jogo extends StatefulWidget {
  const Jogo({Key? key}) : super(key: key);

  @override
  State<Jogo> createState() => _JogoState();
}

class _JogoState extends State<Jogo> {

  var imgApp = AssetImage("images/padrao.png");
  var msg = "Choose an option";

  void selectedOption(String userChoice) {
    var options = ["pedra", "papel", "tesoura"];
    var choice = options[Random().nextInt(3)];

    setState(() {
      imgApp = AssetImage("images/$choice.png");

      if (userChoice == "pedra") {
        if (choice == "papel") msg = "You lost.";
        else if (choice == "tesoura") msg = "You won!";
        else msg = "DRAW.";
      }
      else if (userChoice == "papel") {
        if (choice == "tesoura") msg = "You lost.";
        else if (choice == "pedra") msg = "You won!";
        else msg = "DRAW.";
      }
      else {
        if (choice == "pedra") msg = "You lost.";
        else if (choice == "papel") msg = "You won!";
        else msg = "DRAW.";
      }
    });

  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("JokenPo"),
      ),
      body: Column(
        crossAxisAlignment: CrossAxisAlignment.center,
        children: <Widget>[
          // primeira área da tela: TEXTO
          const Padding(
            padding: EdgeInsets.only(top: 100, bottom: 16),
            child: Text(
              "ENEMY",
              textAlign: TextAlign.center,
              style: TextStyle(
                fontSize: 20,
                fontWeight: FontWeight.bold
              ),
            ),
          ),
          // segunda area: imagem
          Image(image: imgApp, height: 140),
          // terceira area: texto
          Padding(
            padding: const EdgeInsets.only(top: 50, bottom: 16),
            child: Text(
              msg,
              textAlign: TextAlign.center,
              style: const TextStyle(
                  fontSize: 20,
                  fontWeight: FontWeight.bold
              ),
            ),
          ),
          // quarta area: imagem
          Row(
            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
            children: [
              GestureDetector(
                onTap: () => selectedOption("pedra"),
                child: Image.asset("images/pedra.png", height: 100,),
              ),
              GestureDetector(
                onTap: () => selectedOption("papel"),
                child: Image.asset("images/papel.png", height: 100),
              ),
              GestureDetector(
                onTap: () => selectedOption("tesoura"),
                child: Image.asset("images/tesoura.png", height: 100),
              ),
            ],
          )
        ],
      ),
    );
  }
}