Image Resize

import React, { Component } from 'react';
import {
  AppRegistry,
  StyleSheet,
  Text,
  View,
  Button,
  Image
} from 'react-native';
class appTesteWork extends Component {
  constructor(props) {
    super(props);
    this.state = { roundUser : '', roundComputer: '', result : '' }
  }
  showSelectedOption(roundUser) {
    // generate random number (0,1,3)
    var randomNumber = Math.floor(Math.random() * 3);
    var roundComputer = '';
    switch (randomNumber) {
      case 0: roundComputer = 'piedra'; break;
      case 1: roundComputer = 'papel'; break;
      case 2: roundComputer = 'tijera'; break;
    }
    var result = '';
    if (roundComputer == 'piedra') {
      if(roundUser == 'piedra') {
        result = 'Empate';
      }
      if (roundUser == 'papel') {
        result = 'Usuario gano';
      }
      if (roundUser == 'tijera') {
        result = 'Computadora gano';
      }
    }
    if (roundComputer == 'papel') {
      if(roundUser == 'piedra') {
        result = 'Computadora gano';
      }
      if (roundUser == 'papel') {
        result = 'Empate';
      }
      if (roundUser == 'tijera') {
        result = 'Usuario gano';
      }
    }
    if (roundComputer == 'tijera') {
      if(roundUser == 'piedra') {
        result = 'Usuario gano';
      }
      if (roundUser == 'papel') {
        result = 'Computadora gano';
      }
      if (roundUser == 'tijera') {
        result = 'Empate';
      }
    }
    this.setState({ roundUser: roundUser,
                    roundComputer: roundComputer,
                    result: result});
  }
  render() {
    return (
      <View>
        <View>
          <Topo></Topo>
        </View>
        <View style = { styles.panelButtons } >
          <View style = { styles.btnStyle }>
            <Button title="piedra" onPress={ () => { this.showSelectedOption('piedra') } } />
          </View>
          <View style = { styles.btnStyle }>
            <Button title="papel" onPress={ () => { this.showSelectedOption('papel') } }  />
          </View>
          <View style = { styles.btnStyle }>
            <Button title="tijera" onPress={ () => { this.showSelectedOption('tijera') } }  />
          </View>
       </View>
        <View></View>
        <Text>Escolta do computador: { this.state.roundComputer }</Text>
        <Text>Escolta do usuario: { this.state.roundUser }</Text>
        <Text>Resultado: {  this.state.result }</Text>
      </View>
    );
  }
}
class Topo extends Component {
  render() {
    return(
      <View>
        <Image
          resizeMode='cover'
          source = { require('./imgs/jokenpo.png') }
        />
      </View>
    );
  }
}
const styles = StyleSheet.create({
  btnStyle: {
    width: 90
  },
  panelButtons: {
    flexDirection: 'row',
    justifyContent: 'space-between',
    marginTop: 10
  }
});

AppRegistry.registerComponent('appTesteWork', () => appTesteWork);