App.js

import { useState, useRef } from 'react';
import { StyleSheet, View, Platform } from 'react-native';
import { captureRef } from 'react-native-view-shot';
import { BrowserRouter as Router } from "react-router-dom";

import domtoimage from 'dom-to-image';

import { StatusBar } from 'expo-status-bar';
import * as ImagePicker from "expo-image-picker";
import { GestureHandlerRootView } from "react-native-gesture-handler";
import * as MediaLibrary from 'expo-media-library';

import ImageViewer from './components/ImageViewer';
import Button from './components/Button';
import CircleButton from './components/CircleButton';
import IconButton from './components/IconButton';
import EmojiPicker from './components/EmojiPicker';
import EmojiList from './components/EmojiList';
import EmojiSticker from './components/EmojiSticker';

// waiting time of splash screen
// import * as SplashScreen from 'expo-splash-screen';

// SplashScreen.preventAutoHideAsync();
// setTimeout(SplashScreen.hideAsync, 5000);

<Router basename={process.env.PUBLIC_URL}>
  <App />
</Router>

const PlaceHolderImage = require("./assets/images/background-image.jpg");

export default function App() {
  const [selectedImage, setSelectedImage] = useState(null);
  const [showAppOptions, setShowAppOptions] = useState(false);
  const [isModalVisible, setIsModalVisible] = useState(false);
  const [pickedEmoji, setPickedEmoji] = useState(null);
  const [status, requestPermission] = MediaLibrary.usePermissions();

  const imageRef = useRef();

  if (status === null) {
    requestPermission();
  }

  // pick an image
  const pickImageAsync = async () => {
    let result = await ImagePicker.launchImageLibraryAsync({
      // mediaTypes: ImagePicker.MediaTypeOptions.All,
      allowsEditing: true,
      quality: 1,
    });

    if (!result.canceled) {
      setSelectedImage(result.assets[0].uri);
      setShowAppOptions(true);
    } else {
      alert("You did not select any image");
    }
  };

  const onSaveImageAsync = async () => {
    if (Platform.OS !== "web") {
      try {
        const localUri = await captureRef(imageRef, {
          height: 440,
          quality: 1,
        });
  
        await MediaLibrary.saveToLibraryAsync(localUri);
        if (localUri) {
          alert("Saved!");
        }
      } catch (e) {
        console.log(e);
      }
    } else { 
      domtoimage
        .toJpeg(imageRef.current, {
            quality: 0.95,
            width: 320,
            height: 440,
          })
        .then(dataUrl => {
          let link = document.createElement('a');
          link.download = 'sticker-smash.jpeg';
          link.href = dataUrl;
          link.click();
        })
        .catch(e => {
          console.log(e);
        });
    }
    
  };

  const onReset = () => {
    setShowAppOptions(false);
  };

  const onAddSticker = () => {
    setIsModalVisible(true);
  };

  const onModalClose = () => {
    setIsModalVisible(false);
  }

  return (
    <GestureHandlerRootView style={styles.container}>
      <View style={styles.imageContainer}>
        <View ref={imageRef} collapsable={false}>
          <ImageViewer 
            placeholderImageSource={PlaceHolderImage}
            selectedImage={selectedImage}/>
          {pickedEmoji !== null ? (
            <EmojiSticker imageSize={40} stickerSource={pickedEmoji}/>
          ) : null}
        </View>
      </View>

      {showAppOptions ? (
        <View style={styles.optionsContainer}>
          <View style={styles.optionsRow}>
            <IconButton icon="refresh" label="Reset" onPress={onReset}/>
            <CircleButton onPress={onAddSticker}/>
            <IconButton icon="save-alt" label="Save" onPress={onSaveImageAsync}/>
          </View>
        </View>
        ) : (
          <View style={styles.footerContainer}>
            <Button theme="primary" label="Choose a photo" onPress={pickImageAsync}/>
            <Button label="Use this photo" onPress={() => setShowAppOptions(true)}/>
          </View>
        )}

      <EmojiPicker isVisible={isModalVisible} onClose={onModalClose}
        emojiList={
          <EmojiList onSelect={setPickedEmoji} onCloseModal={onModalClose}
        />}
      />

      <StatusBar style="light" />
    </GestureHandlerRootView>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#25292e',
    alignItems: 'center',
    justifyContent: 'center',
  },
  imageContainer: {
    flex:1,
    paddingTop:58,
  },
  footerContainer: {
    flex: 1 / 3,
    alignItems: "center",
  },
  optionsContainer: {
    position: "absolute",
    bottom: 80,
  },
  optionsRow: {
    alignItems: "center",
    flexDirection: "row",
  },
});