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, thanks for sharing

Hi @eveningkid , I've been trying to get this to work on an iPhone. Everything seems fine except the scroll up response to dragging to the top or bottom only scrolls a tiny bit when and only scrolls while your finger is moving. It looks like the gesture handler is killing the withTiming function for setting the scrollY.value. Any idea how to fix this? I have created a snack for it: https://snack.expo.dev/@stewartarmbrecht/apple-music-drag-to-sort

I think I figured it out. New snack here: https://snack.expo.dev/@stewartarmbrecht/apple-music-drag-and-sort-working

@Stewartarmbrecht thank you so much. I was having the exact same issue on Android and was desperatly trying to fix it. I wish I would have checked the comments immediately.

So if anybody else is having this issue: Stewart's snack is still working 👍

how about if i want to make the height variable?

@Stewartarmbrecht your fix works well, but it looks like theres an issue if you drop the song while it's still scrolling it doesn't seem to fit in where it's supposed to.

@Stewartarmbrecht Thank you for your help 👍

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