daily Programming: react-native & expo

原本 2021 計畫之一是 寫一個 Flutter 的 app

正所謂 計畫趕不上變化 變化趕不上我閃亮亮的情緒化!

改成用 expo (react-native 的 framework) 寫一個 app!

把 網頁版本的 改成 app!

廢話不多說!

開工寫筆記!

本筆記會一直成長唷唷

Expo

• Start

       # Install 
       npm install --global expo-cli
  
       # Create a new project
       expo init my-porject
  

抓手機相機

• expo-camera Installation

expo install expo-camera

• usage

import React, { useState, useEffect } from 'react';
import { StyleSheet, Text, View, TouchableOpacity } from 'react-native';
import { Camera } from 'expo-camera';

export default function App() {
  const [hasPermission, setHasPermission] = useState(null);
  const [type, setType] = useState(Camera.Constants.Type.back);

  useEffect(() => {
    (async () => {
      const { status } = await Camera.requestPermissionsAsync();
      setHasPermission(status === 'granted');
    })();
  }, []);

  if (hasPermission === null) {
    return <View />;
  }
  if (hasPermission === false) {
    return <Text>No access to camera</Text>;
  }
  return (
    <View style={styles.container}>
      <Camera style={styles.camera} type={type}>
        <View style={styles.buttonContainer}>
          <TouchableOpacity
            style={styles.button}
            onPress={() => {
              setType(
                type === Camera.Constants.Type.back
                  ? Camera.Constants.Type.front
                  : Camera.Constants.Type.back
              );
            }}>
            <Text style={styles.text}> Flip </Text>
          </TouchableOpacity>
        </View>
      </Camera>
    </View>
  );
}

• 確定畫面已經都 Focuse 才開相機

import { useIsFocused } from '@react-navigation/native'
import { Camera } from 'expo-camera'
// ...

export default function xxx() {
  const isFocus = useIsFocused()
  // ...
  
  return ( <View> 
     { isFocus && <Camera></Camra>}
  
  </View>)
}