[[oktatas:telefon:react_native|< React Native]]

====== React Native - Bevitel ======

  * **Szerző:** Sallai András
  * Copyright (c) Sallai András, 2023
  * Licenc: [[https://creativecommons.org/licenses/by-sa/4.0/|CC Attribution-Share Alike 4.0 International]]
  * Web: https://szit.hu

===== Triangle =====
==== Terület TextInputban ====

<code javascript App.js>
import { StatusBar } from 'expo-status-bar';
import { useState } from 'react';
import { StyleSheet, Text, TouchableHighlight, View } from 'react-native';
import { TextInput } from 'react-native';

function calcTriangleArea(base, height) {
  return base * height / 2;
}

export default function App() {
  const [base, setBase] = useState('');
  const [height, setHeight] = useState('');
  const [area, setArea] = useState('');
  function startCalc() {
    let result = calcTriangleArea(base, height);
    setArea(result);
  }
  return (
    <View style={styles.container}>
      <Text>Triangle</Text>
      <Text>Háromszög területszámítás</Text>

      <Text>Alap</Text>
      <TextInput
      style={styles.input}
      onChangeText={base => setBase(base)}
      />

      <Text>Magasság</Text>
      <TextInput
      style={styles.input}
      onChangeText={height => setHeight(height)}
      />

      <TouchableHighlight
        style={styles.button}
        onPress={startCalc}
      >
        <Text style={styles.buttonText}>Számít</Text>
      </TouchableHighlight>

      <Text>Terület</Text>
      {/* TERÜLET */}
      <TextInput
      style={styles.input}
      onChangeText={area => setArea(area)}
      value={area}
      />

      <StatusBar style="auto" />
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: 'aqua',
    alignItems: 'center',
    justifyContent: 'center',
  },
  button: {
    backgroundColor: 'blue',
    marginTop: 10,
    padding: 10,
    borderRadius: 3,

  },
  butotnText: {
    color: 'white',
    paddingLeft: 10,
    paddingRight: 10,
    fontSize: 22,
  },
  input: {
    backgroundColor: 'white',
    height: 30,
  }
});
</code>

==== Terület Textben ====

<code javascript App.js>
import { StatusBar } from 'expo-status-bar';
import { useState } from 'react';
import { StyleSheet, Text, TouchableHighlight, View } from 'react-native';
import { TextInput } from 'react-native';

function calcTriangleArea(base, height) {
  return base * height / 2;
}

export default function App() {
  const [base, setBase] = useState('');
  const [height, setHeight] = useState('');
  const [area, setArea] = useState('');
  function startCalc() {
    let result = calcTriangleArea(base, height);
    setArea(result);
  }
  return (
    <View style={styles.container}>
      <Text>Triangle</Text>
      <Text>Háromszög területszámítás</Text>

      <Text>Alap</Text>
      <TextInput
      style={styles.input}
      onChangeText={base => setBase(base)}
      />

      <Text>Magasság</Text>
      <TextInput
      style={styles.input}
      onChangeText={height => setHeight(height)}
      />

      <TouchableHighlight
        style={styles.button}
        onPress={startCalc}
      >
        <Text style={styles.buttonText}>Számít</Text>
      </TouchableHighlight>

      <Text>Terület</Text>
      <Text>{area}</Text>

      <StatusBar style="auto" />
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: 'aqua',
    alignItems: 'center',
    justifyContent: 'center',
  },
  button: {
    backgroundColor: 'blue',
    marginTop: 10,
    padding: 10,
    borderRadius: 3,

  },
  butotnText: {
    color: 'white',
    paddingLeft: 10,
    paddingRight: 10,
    fontSize: 22,
  },
  input: {
    backgroundColor: 'white',
    height: 30,
  }
});

</code>

===== A gomb külön fájlban =====

<code javascript Buttonjs>
import React from 'react';
import { StyleSheet, Text, TouchableHighlight } from 'react-native';

const Button = (props) => {
    return (
        <TouchableHighlight
        style={styles.button}
        onPress={props.onPress}
        >
            <Text style={styles.buttonText}>Számít</Text>
        </TouchableHighlight>

    );
}

export default Button;

const styles = StyleSheet.create({
    button: {
        backgroundColor: 'blue',
        marginTop: 10,
        padding: 10,
        borderRadius: 3,

    },
    buttonText: {
        color: 'white',
        paddingLeft: 10,
        paddingRight: 10,
        fontSize: 22,
    },    
});
</code>


<code javascript App.js>
import { StatusBar } from 'expo-status-bar';
import { useState } from 'react';
import { StyleSheet, Text, TouchableHighlight, View } from 'react-native';
import { TextInput } from 'react-native';
import Button from './components/Button';

function calcTriangleArea(base, height) {
  return base * height / 2;
}

export default function App() {
  const [base, setBase] = useState('');
  const [height, setHeight] = useState('');
  const [area, setArea] = useState('');
  function startCalc() {
    let result = calcTriangleArea(base, height);
    setArea(result);
  }
  return (
    <View style={styles.container}>
      <Text>Triangle</Text>
      <Text>Háromszög területszámítás</Text>

      <Text>Alap</Text>
      <TextInput
      style={styles.input}
      onChangeText={base => setBase(base)}
      />


      <Text>Magasság</Text>
      <TextInput
      style={styles.input}
      onChangeText={height => setHeight(height)}
      />

      <Button onPress={startCalc} />

      <Text>Terület</Text>
      <Text>{area}</Text>

      <StatusBar style="auto" />
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: 'aqua',
    alignItems: 'center',
    justifyContent: 'center',
  },

  input: {
    backgroundColor: 'white',
    height: 30,
  }
});

</code>