React Native Reanimated 2 Multiple Drag and Sort: Apple Music Example

react-native-reanimated-drag-sort_apple-music.jsx

// Expo SDK40
// expo-blur: ~8.2.2
// expo-haptics: ~8.4.0
// react-native-gesture-handler: ~1.8.0
// react-native-reanimated: ^2.0.0-rc.0
// react-native-safe-area-context: 3.1.9

import React, { useState } from 'react';
import {
  Image,
  Platform,
  StatusBar,
  Text,
  useWindowDimensions,
  View,
} from 'react-native';
import {
  SafeAreaProvider,
  SafeAreaView,
  useSafeAreaInsets,
} from 'react-native-safe-area-context';
import Animated, {
  cancelAnimation,
  runOnJS,
  scrollTo,
  useAnimatedGestureHandler,
  useAnimatedReaction,
  useAnimatedRef,
  useAnimatedScrollHandler,
  useAnimatedStyle,
  useSharedValue,
  withSpring,
  withTiming,
} from 'react-native-reanimated';
import { PanGestureHandler } from 'react-native-gesture-handler';
import * as Haptics from 'expo-haptics';
import { BlurView } from 'expo-blur';

function clamp(value, lowerBound, upperBound) {
  'worklet';
  return Math.max(lowerBound, Math.min(value, upperBound));
}

function shuffle(array) {
  let counter = array.length;

  while (counter > 0) {
    let index = Math.floor(Math.random() * counter);
    counter--;
    let temp = array[counter];
    array[counter] = array[index];
    array[index] = temp;
  }

  return array;
}

function objectMove(object, from, to) {
  'worklet';
  const newObject = Object.assign({}, object);

  for (const id in object) {
    if (object[id] === from) {
      newObject[id] = to;
    }

    if (object[id] === to) {
      newObject[id] = from;
    }
  }

  return newObject;
}

function listToObject(list) {
  const values = Object.values(list);
  const object = {};

  for (let i = 0; i < values.length; i++) {
    object[values[i].id] = i;
  }

  return object;
}

const ALBUM_COVERS = {
  DISCOVERY:
    'https://upload.wikimedia.org/wikipedia/en/a/ae/Daft_Punk_-_Discovery.jpg',
  HUMAN_AFTER_ALL:
    'https://upload.wikimedia.org/wikipedia/en/0/0d/Humanafterall.jpg',
  HOMEWORK:
    'https://upload.wikimedia.org/wikipedia/en/9/9c/Daftpunk-homework.jpg',
  RANDOM_ACCESS_MEMORIES:
    'https://upload.wikimedia.org/wikipedia/en/a/a7/Random_Access_Memories.jpg',
};

const DAFT_PUNK = 'Daft Punk';

const SONGS = shuffle([
  {
    id: 'one-more-time',
    title: 'One More Time',
    artist: DAFT_PUNK,
    cover: ALBUM_COVERS.DISCOVERY,
  },
  {
    id: 'digital-love',
    title: 'Digital Love',
    artist: DAFT_PUNK,
    cover: ALBUM_COVERS.DISCOVERY,
  },
  {
    id: 'nightvision',
    title: 'Nightvision',
    artist: DAFT_PUNK,
    cover: ALBUM_COVERS.DISCOVERY,
  },
  {
    id: 'something-about-us',
    title: 'Something About Us',
    artist: DAFT_PUNK,
    cover: ALBUM_COVERS.DISCOVERY,
  },
  {
    id: 'veridis-quo',
    title: 'Veridis Quo',
    artist: DAFT_PUNK,
    cover: ALBUM_COVERS.DISCOVERY,
  },
  {
    id: 'make-love',
    title: 'Make Love',
    artist: DAFT_PUNK,
    cover: ALBUM_COVERS.HUMAN_AFTER_ALL,
  },
  {
    id: 'television-rules-the-nation',
    title: 'Television Rules the Nation',
    artist: DAFT_PUNK,
    cover: ALBUM_COVERS.HUMAN_AFTER_ALL,
  },
  {
    id: 'phoenix',
    title: 'Phoenix',
    artist: DAFT_PUNK,
    cover: ALBUM_COVERS.HOMEWORK,
  },
  {
    id: 'revolution-909',
    title: 'Revolution 909',
    artist: DAFT_PUNK,
    cover: ALBUM_COVERS.HOMEWORK,
  },
  {
    id: 'around-the-world',
    title: 'Around the World',
    artist: DAFT_PUNK,
    cover: ALBUM_COVERS.HOMEWORK,
  },
  {
    id: 'within',
    title: 'Within',
    artist: DAFT_PUNK,
    cover: ALBUM_COVERS.RANDOM_ACCESS_MEMORIES,
  },
  {
    id: 'touch',
    title: 'Touch (feat. Paul Williams)',
    artist: DAFT_PUNK,
    cover: ALBUM_COVERS.RANDOM_ACCESS_MEMORIES,
  },
  {
    id: 'beyond',
    title: 'Beyond',
    artist: DAFT_PUNK,
    cover: ALBUM_COVERS.RANDOM_ACCESS_MEMORIES,
  },
  {
    id: 'motherboard',
    title: 'Motherboard',
    artist: DAFT_PUNK,
    cover: ALBUM_COVERS.RANDOM_ACCESS_MEMORIES,
  },
]);

const SONG_HEIGHT = 70;
const SCROLL_HEIGHT_THRESHOLD = SONG_HEIGHT;

function Song({ artist, cover, title }) {
  return (
    <View
      style={{
        flexDirection: 'row',
        alignItems: 'center',
        height: SONG_HEIGHT,
        padding: 10,
      }}
    >
      <Image
        source={{ uri: cover }}
        style={{ height: 50, width: 50, borderRadius: 4 }}
      />

      <View
        style={{
          marginLeft: 10,
        }}
      >
        <Text
          style={{
            fontSize: 16,
            fontWeight: '600',
            marginBottom: 4,
          }}
        >
          {title}
        </Text>

        <Text style={{ fontSize: 12, color: 'gray' }}>{artist}</Text>
      </View>
    </View>
  );
}

function MovableSong({
  id,
  artist,
  cover,
  title,
  positions,
  scrollY,
  songsCount,
}) {
  const dimensions = useWindowDimensions();
  const insets = useSafeAreaInsets();
  const [moving, setMoving] = useState(false);
  const top = useSharedValue(positions.value[id] * SONG_HEIGHT);

  useAnimatedReaction(
    () => positions.value[id],
    (currentPosition, previousPosition) => {
      if (currentPosition !== previousPosition) {
        if (!moving) {
          top.value = withSpring(currentPosition * SONG_HEIGHT);
        }
      }
    },
    [moving]
  );

  const gestureHandler = useAnimatedGestureHandler({
    onStart() {
      runOnJS(setMoving)(true);

      if (Platform.OS === 'ios') {
        runOnJS(Haptics.impactAsync)(
          Haptics.ImpactFeedbackStyle.Medium
        );
      }
    },
    onActive(event) {
      const positionY = event.absoluteY + scrollY.value;

      if (positionY <= scrollY.value + SCROLL_HEIGHT_THRESHOLD) {
        // Scroll up
        scrollY.value = withTiming(0, { duration: 1500 });
      } else if (
        positionY >=
        scrollY.value + dimensions.height - SCROLL_HEIGHT_THRESHOLD
      ) {
        // Scroll down
        const contentHeight = songsCount * SONG_HEIGHT;
        const containerHeight =
          dimensions.height - insets.top - insets.bottom;
        const maxScroll = contentHeight - containerHeight;
        scrollY.value = withTiming(maxScroll, { duration: 1500 });
      } else {
        cancelAnimation(scrollY);
      }

      top.value = withTiming(positionY - SONG_HEIGHT, {
        duration: 16,
      });

      const newPosition = clamp(
        Math.floor(positionY / SONG_HEIGHT),
        0,
        songsCount - 1
      );

      if (newPosition !== positions.value[id]) {
        positions.value = objectMove(
          positions.value,
          positions.value[id],
          newPosition
        );

        if (Platform.OS === 'ios') {
          runOnJS(Haptics.impactAsync)(
            Haptics.ImpactFeedbackStyle.Light
          );
        }
      }
    },
    onFinish() {
      top.value = positions.value[id] * SONG_HEIGHT;
      runOnJS(setMoving)(false);
    },
  });

  const animatedStyle = useAnimatedStyle(() => {
    return {
      position: 'absolute',
      left: 0,
      right: 0,
      top: top.value,
      zIndex: moving ? 1 : 0,
      shadowColor: 'black',
      shadowOffset: {
        height: 0,
        width: 0,
      },
      shadowOpacity: withSpring(moving ? 0.2 : 0),
      shadowRadius: 10,
    };
  }, [moving]);

  return (
    <Animated.View style={animatedStyle}>
      <BlurView intensity={moving ? 100 : 0} tint="light">
        <PanGestureHandler onGestureEvent={gestureHandler}>
          <Animated.View style={{ maxWidth: '80%' }}>
            <Song artist={artist} cover={cover} title={title} />
          </Animated.View>
        </PanGestureHandler>
      </BlurView>
    </Animated.View>
  );
}

export default function App() {
  const positions = useSharedValue(listToObject(SONGS));
  const scrollY = useSharedValue(0);
  const scrollViewRef = useAnimatedRef();

  useAnimatedReaction(
    () => scrollY.value,
    (scrolling) => scrollTo(scrollViewRef, 0, scrolling, false)
  );

  const handleScroll = useAnimatedScrollHandler((event) => {
    scrollY.value = event.contentOffset.y;
  });

  return (
    <>
      <StatusBar barStyle="dark-content" />
      <SafeAreaProvider>
        <SafeAreaView style={{ flex: 1 }}>
          <Animated.ScrollView
            ref={scrollViewRef}
            onScroll={handleScroll}
            scrollEventThrottle={16}
            style={{
              flex: 1,
              position: 'relative',
              backgroundColor: 'white',
            }}
            contentContainerStyle={{
              height: SONGS.length * SONG_HEIGHT,
            }}
          >
            {SONGS.map((song) => (
              <MovableSong
                key={song.id}
                id={song.id}
                artist={song.artist}
                cover={song.cover}
                title={song.title}
                positions={positions}
                scrollY={scrollY}
                songsCount={SONGS.length}
              />
            ))}
          </Animated.ScrollView>
        </SafeAreaView>
      </SafeAreaProvider>
    </>
  );
}

Hello. For everyone who has issues with @Stewartarmbrecht `s snack while the scrollView is scrolling and the item is not correct positioned afterwards. The reason is that moving is still using useState. It should be a SharedValue. This small changes fixes the incorrect placement when dropping an item while scrolling.

Thanks a lot though. Without this snack I would have needed an expensive amount of more time :)

If i'm adding heading on the top then the movable songs not starting from the initial p[osiotion it started from little downword

Thanks @Stewartarmbrecht Nice snack here, saved lot of my time. The scrollTo crashes the app the on the latest RN fabric with react-native-gesture-handler @ 2.18.1 & [email protected], Yes there are some deprecations in the new API like useAnimatedGestureHandler but i have replaced them with the newer API's. Do you have any idea or guess on the app screen on scrollTo?

I'm not sure what you are asking. Are you if I have an idea why scrollTo crashes the app? Unfortunately, I don't. But I should be getting back to that soon. Currently working on foundation stuff (monorepo for building multiple universal expo apps that share code). I'll look at adding this into the demo app and see if I can recreate/fix then. I'll share the repo here when it's ready.

Yes. Also I have raised the issue software-mansion/react-native-reanimated#6418 and it is with the RN framework.