react-native-reanimated#event TypeScript Examples

StickyItemFlatList = forwardRef(
  <T extends {}>(props: StickyItemFlatListProps<T>, ref: Ref<FlatList<T>>) => {
    const {
      initialScrollIndex = 0,
      decelerationRate = DEFAULT_DECELERATION_RATE,
      itemWidth,
      itemHeight,
      separatorSize = DEFAULT_SEPARATOR_SIZE,
      borderRadius = DEFAULT_BORDER_RADIUS,
      stickyItemActiveOpacity = DEFAULT_STICKY_ITEM_ACTIVE_OPACITY,
      stickyItemWidth,
      stickyItemHeight,
      stickyItemBackgroundColors,
      stickyItemContent,
      onStickyItemPress,
      isRTL = DEFAULT_IS_RTL,
      ItemSeparatorComponent = Separator,
      ...rest
    } = props;

    // refs
    const flatListRef = useRef<FlatList<T>>(null);
    const tapRef = useRef<TapGestureHandler>(null);

    //#region variables
    const itemWidthWithSeparator = useMemo(
      () => itemWidth + separatorSize,
      [itemWidth, separatorSize]
    );
    const separatorProps = useMemo(
      () => ({
        size: separatorSize,
      }),
      [separatorSize]
    );
    //#endregion

    //#region styles
    const contentContainerStyle = useMemo(
      () => [
        rest.contentContainerStyle,
        {
          paddingLeft: itemWidth + separatorSize * 2,
          paddingRight: separatorSize,
        },
      ],
      [rest.contentContainerStyle, itemWidth, separatorSize]
    );
    //#endregion

    //#region methods
    const getHitSlop = useCallback(
      isMinimized => {
        const verticalPosition = isMinimized
          ? -((itemHeight - stickyItemHeight) / 2)
          : 0;
        const startPosition = isMinimized ? 0 : -separatorSize;
        const endPosition = isMinimized
          ? -(SCREEN_WIDTH - stickyItemWidth)
          : -(SCREEN_WIDTH - separatorSize - itemWidth);

        return {
          top: verticalPosition,
          right: isRTL ? startPosition : endPosition,
          left: isRTL ? endPosition : startPosition,
          bottom: verticalPosition,
        };
      },
      [
        itemWidth,
        itemHeight,
        stickyItemWidth,
        stickyItemHeight,
        separatorSize,
        isRTL,
      ]
    );
    const getItemLayout = useCallback(
      (_, index) => {
        return {
          length: itemWidthWithSeparator,
          // sticky item + previous items width
          offset: itemWidthWithSeparator + itemWidthWithSeparator * index,
          index,
        };
      },
      [itemWidthWithSeparator]
    );
    //#endregion

    //#region gesture
    const x = useValue(0);
    const tapState = useValue(State.UNDETERMINED);
    const tapGestures = useGestureHandler({ state: tapState });
    const onScroll = event([
      {
        nativeEvent: {
          contentOffset: {
            x,
          },
        },
      },
    ]);
    const onScrollEnd = event([
      {
        nativeEvent: {
          contentOffset: {
            x,
          },
        },
      },
    ]);
    //#endregion

    //#region effects
    //@ts-ignore
    useImperativeHandle(ref, () => flatListRef.current!.getNode());
    useCode(
      () =>
        cond(eq(tapState, State.END), [
          call([tapState], () => {
            if (onStickyItemPress) {
              onStickyItemPress();
            }
          }),
          set(tapState, State.UNDETERMINED),
        ]),
      [tapState]
    );
    useCode(
      () =>
        onChange(
          x,
          call([x], args => {
            if (tapRef.current) {
              const isMinimized = args[0] > 0;
              // @ts-ignore
              tapRef.current.setNativeProps({
                hitSlop: getHitSlop(isMinimized),
              });
            }
          })
        ),
      [
        x,
        itemWidth,
        itemHeight,
        stickyItemWidth,
        stickyItemWidth,
        separatorSize,
      ]
    );
    useEffect(() => {
      /**
       * @DEV
       * to fix stick item position with fast refresh
       */
      x.setValue(0);

      if (tapRef.current) {
        // @ts-ignore
        tapRef.current.setNativeProps({
          hitSlop: getHitSlop(initialScrollIndex !== 0),
        });
      }
      // eslint-disable-next-line react-hooks/exhaustive-deps
    }, [getHitSlop]);
    //#endregion

    // render
    const renderSeparator = useCallback(() => {
      if (typeof ItemSeparatorComponent === 'function') {
        // @ts-ignore
        return ItemSeparatorComponent(separatorProps);
      } else {
        // @ts-ignore
        return <ItemSeparatorComponent size={separatorProps.size} />;
      }
    }, [ItemSeparatorComponent, separatorProps]);

    return (
      <TapGestureHandler
        ref={tapRef}
        waitFor={flatListRef}
        shouldCancelWhenOutside={true}
        {...tapGestures}
      >
        <Animated.View>
          <AnimatedFlatList
            {...rest}
            ref={flatListRef}
            initialScrollIndex={initialScrollIndex}
            inverted={isRTL}
            ItemSeparatorComponent={renderSeparator}
            contentContainerStyle={contentContainerStyle}
            horizontal={true}
            showsHorizontalScrollIndicator={false}
            scrollEventThrottle={1}
            pagingEnabled={true}
            decelerationRate={decelerationRate}
            snapToAlignment={'start'}
            snapToInterval={itemWidth + separatorSize}
            onScroll={onScroll}
            onScrollAnimationEnd={onScrollEnd}
            getItemLayout={getItemLayout}
          />
          <StickyItem
            x={x}
            tapState={tapState}
            itemWidth={itemWidth}
            itemHeight={itemHeight}
            separatorSize={separatorSize}
            borderRadius={borderRadius}
            stickyItemActiveOpacity={stickyItemActiveOpacity}
            stickyItemWidth={stickyItemWidth}
            stickyItemHeight={stickyItemHeight}
            stickyItemBackgroundColors={stickyItemBackgroundColors}
            stickyItemContent={stickyItemContent}
            isRTL={isRTL}
          />
        </Animated.View>
      </TapGestureHandler>
    );
  }
)

constructor(props: Props<T>) {
    super(props);
    const { initialSnapIndex, animationType } = props;

    const animationDriver = animationType === 'timing' ? 0 : 1;
    const animationDuration =
      (props.animationType === 'timing' && props.animationConfig?.duration) ||
      DEFAULT_ANIMATION_DURATION;

    const ScrollComponent = this.getScrollComponent();
    // @ts-ignore
    this.scrollComponent = Animated.createAnimatedComponent(ScrollComponent);

    const snapPoints = this.getNormalisedSnapPoints();
    const openPosition = snapPoints[0];
    const closedPosition = this.props.enableOverScroll
      ? windowHeight
      : snapPoints[snapPoints.length - 1];
    const initialSnap = snapPoints[initialSnapIndex];
    this.nextSnapIndex = new Value(initialSnapIndex);

    const initialDecelerationRate = Platform.select({
      android:
        props.initialSnapIndex === 0 ? ANDROID_NORMAL_DECELERATION_RATE : 0,
      ios: IOS_NORMAL_DECELERATION_RATE,
    });
    this.decelerationRate = new Value(initialDecelerationRate);

    const handleGestureState = new Value<GestureState>(-1);
    const handleOldGestureState = new Value<GestureState>(-1);
    const drawerGestureState = new Value<GestureState>(-1);
    const drawerOldGestureState = new Value<GestureState>(-1);

    const lastSnapInRange = new Value(1);
    this.prevTranslateYOffset = new Value(initialSnap);
    this.translationY = new Value(initialSnap);

    this.lastSnap = new Value(initialSnap);

    this.onHandleGestureEvent = event([
      {
        nativeEvent: {
          translationY: this.dragY,
          oldState: handleOldGestureState,
          state: handleGestureState,
          velocityY: this.velocityY,
        },
      },
    ]);
    this.onDrawerGestureEvent = event([
      {
        nativeEvent: {
          translationY: this.dragY,
          oldState: drawerOldGestureState,
          state: drawerGestureState,
          velocityY: this.velocityY,
        },
      },
    ]);
    this.onScrollBeginDrag = event([
      {
        nativeEvent: {
          contentOffset: { y: this.lastStartScrollY },
        },
      },
    ]);

    const didHandleGestureBegin = eq(handleGestureState, GestureState.ACTIVE);

    const isAnimationInterrupted = and(
      or(
        eq(handleGestureState, GestureState.BEGAN),
        eq(drawerGestureState, GestureState.BEGAN),
        and(
          eq(this.isAndroid, 0),
          eq(animationDriver, 1),
          or(
            eq(drawerGestureState, GestureState.ACTIVE),
            eq(handleGestureState, GestureState.ACTIVE)
          )
        )
      ),
      clockRunning(this.animationClock)
    );

    this.didGestureFinish = or(
      and(
        eq(handleOldGestureState, GestureState.ACTIVE),
        eq(handleGestureState, GestureState.END)
      ),
      and(
        eq(drawerOldGestureState, GestureState.ACTIVE),
        eq(drawerGestureState, GestureState.END)
      )
    );

    // Function that determines if the last snap point is in the range {snapPoints}
    // In the case of interruptions in the middle of an animation, we'll get
    // lastSnap values outside the range
    const isLastSnapPointInRange = (i: number = 0): Animated.Node<number> =>
      i === snapPoints.length
        ? lastSnapInRange
        : cond(
            eq(this.lastSnap, snapPoints[i]),
            [set(lastSnapInRange, 1)],
            isLastSnapPointInRange(i + 1)
          );

    const scrollY = [
      set(lastSnapInRange, 0),
      isLastSnapPointInRange(),
      cond(
        or(
          didHandleGestureBegin,
          and(
            this.isManuallySetValue,
            not(eq(this.manualYOffset, snapPoints[0]))
          )
        ),
        [set(this.dragWithHandle, 1), 0]
      ),
      cond(
        // This is to account for a continuous scroll on the drawer from a snap point
        // Different than top, bringing the drawer to the top position, so that if we
        // change scroll direction without releasing the gesture, it doesn't pull down the drawer again
        and(
          eq(this.dragWithHandle, 1),
          greaterThan(snapPoints[0], add(this.lastSnap, this.dragY)),
          and(not(eq(this.lastSnap, snapPoints[0])), lastSnapInRange)
        ),
        [
          set(this.lastSnap, snapPoints[0]),
          set(this.dragWithHandle, 0),
          this.lastStartScrollY,
        ],
        cond(eq(this.dragWithHandle, 1), 0, this.lastStartScrollY)
      ),
    ];

    this.didScrollUpAndPullDown = cond(
      and(
        greaterOrEq(this.dragY, this.lastStartScrollY),
        greaterThan(this.lastStartScrollY, 0)
      ),
      set(this.scrollUpAndPullDown, 1)
    );

    this.setTranslationY = cond(
      and(
        not(this.dragWithHandle),
        not(greaterOrEq(this.dragY, this.lastStartScrollY))
      ),
      set(this.translationY, sub(this.dragY, this.lastStartScrollY)),
      set(this.translationY, this.dragY)
    );

    this.extraOffset = cond(
      eq(this.scrollUpAndPullDown, 1),
      this.lastStartScrollY,
      0
    );
    const endOffsetY = add(
      this.lastSnap,
      this.translationY,
      multiply(1 - props.friction, this.velocityY)
    );

    this.calculateNextSnapPoint = (i = 0): Animated.Node<number> | number =>
      i === snapPoints.length
        ? this.tempDestSnapPoint
        : cond(
            greaterThan(
              abs(sub(this.tempDestSnapPoint, endOffsetY)),
              abs(sub(add(snapPoints[i], this.extraOffset), endOffsetY))
            ),
            [
              set(this.tempDestSnapPoint, add(snapPoints[i], this.extraOffset)),
              set(this.nextSnapIndex, i),
              this.calculateNextSnapPoint(i + 1),
            ],
            this.calculateNextSnapPoint(i + 1)
          );

    const runAnimation = ({
      clock,
      from,
      to,
      position,
      finished,
      velocity,
      frameTime,
    }: TimingParams) => {
      const state = {
        finished,
        velocity: new Value(0),
        position,
        time: new Value(0),
        frameTime,
      };

      const timingConfig = {
        duration: animationDuration,
        easing:
          (props.animationType === 'timing' && props.animationConfig?.easing) ||
          DEFAULT_EASING,
        toValue: new Value(0),
      };

      const springConfig = {
        ...DEFAULT_SPRING_PARAMS,
        ...((props.animationType === 'spring' && props.animationConfig) || {}),
        toValue: new Value(0),
      };

      return [
        cond(and(not(clockRunning(clock)), not(eq(finished, 1))), [
          // If the clock isn't running, we reset all the animation params and start the clock
          set(state.finished, 0),
          set(state.velocity, velocity),
          set(state.time, 0),
          set(state.position, from),
          set(state.frameTime, 0),
          set(timingConfig.toValue, to),
          set(springConfig.toValue, to),
          startClock(clock),
        ]),
        // We run the step here that is going to update position
        cond(
          eq(animationDriver, 0),
          timing(clock, state, timingConfig),
          spring(clock, state, springConfig)
        ),
        cond(
          state.finished,
          [
            call([this.nextSnapIndex], ([value]) => {
              if (value !== this.prevSnapIndex) {
                this.props.onSettle?.(value);
              }
              this.prevSnapIndex = value;
            }),
            // Resetting appropriate values
            set(drawerOldGestureState, GestureState.END),
            set(handleOldGestureState, GestureState.END),
            set(this.prevTranslateYOffset, state.position),
            cond(eq(this.scrollUpAndPullDown, 1), [
              set(
                this.prevTranslateYOffset,
                sub(this.prevTranslateYOffset, this.lastStartScrollY)
              ),
              set(this.lastStartScrollY, 0),
              set(this.scrollUpAndPullDown, 0),
            ]),
            cond(eq(this.destSnapPoint, snapPoints[0]), [
              set(this.dragWithHandle, 0),
            ]),
            set(this.isManuallySetValue, 0),
            set(this.manualYOffset, 0),
            stopClock(clock),
            this.prevTranslateYOffset,
          ],
          // We made the block return the updated position,
          state.position
        ),
      ];
    };

    const translateYOffset = cond(
      isAnimationInterrupted,
      [
        // set(prevTranslateYOffset, animationPosition) should only run if we are
        // interrupting an animation when the drawer is currently in a different
        // position than the top
        cond(
          or(
            this.dragWithHandle,
            greaterOrEq(abs(this.prevDragY), this.lastStartScrollY)
          ),
          set(this.prevTranslateYOffset, this.animationPosition)
        ),
        set(this.animationFinished, 1),
        set(this.translationY, 0),
        // Resetting appropriate values
        set(drawerOldGestureState, GestureState.END),
        set(handleOldGestureState, GestureState.END),
        // By forcing that frameTime exceeds duration, it has the effect of stopping the animation
        set(this.animationFrameTime, add(animationDuration, 1000)),
        set(this.velocityY, 0),
        stopClock(this.animationClock),
        this.prevTranslateYOffset,
      ],
      cond(
        or(
          this.didGestureFinish,
          this.isManuallySetValue,
          clockRunning(this.animationClock)
        ),
        [
          runAnimation({
            clock: this.animationClock,
            from: cond(
              this.isManuallySetValue,
              this.prevTranslateYOffset,
              add(this.prevTranslateYOffset, this.translationY)
            ),
            to: this.destSnapPoint,
            position: this.animationPosition,
            finished: this.animationFinished,
            frameTime: this.animationFrameTime,
            velocity: this.velocityY,
          }),
        ],
        [
          set(this.animationFrameTime, 0),
          set(this.animationFinished, 0),
          // @ts-ignore
          this.prevTranslateYOffset,
        ]
      )
    );

    this.translateY = interpolate(
      add(translateYOffset, this.dragY, multiply(scrollY, -1)),
      {
        inputRange: [openPosition, closedPosition],
        outputRange: [openPosition, closedPosition],
        extrapolate: Extrapolate.CLAMP,
      }
    );

    this.position = interpolate(this.translateY, {
      inputRange: [openPosition, snapPoints[snapPoints.length - 1]],
      outputRange: [1, 0],
      extrapolate: Extrapolate.CLAMP,
    });
  }