react-native-reanimated#withSpring TypeScript Examples

usedWorklets = {
  withTiming,
  withSpring,
  bezier: Easing.bezier,
  interpolate,
  withDecay,
  useAnimatedGestureHandler,
  ...usedVectors,
} as { [key: string]: any }

export function LineChartCursorCrosshair({
  children,
  color = 'black',
  size = 8,
  outerSize = 32,
  crosshairWrapperProps = {},
  crosshairProps = {},
  crosshairOuterProps = {},
  ...props
}: LineChartCursorCrosshairProps) {
  const { currentX, currentY, isActive } = useLineChart();

  // It seems that enabling spring animation on initial render on Android causes a crash.
  const [enableSpringAnimation, setEnableSpringAnimation] = React.useState(
    Platform.OS === 'ios'
  );
  React.useEffect(() => {
    setTimeout(() => {
      setEnableSpringAnimation(true);
    }, 100);
  }, []);

  const animatedCursorStyle = useAnimatedStyle(() => ({
    transform: [
      { translateX: currentX.value - outerSize / 2 },
      { translateY: currentY.value - outerSize / 2 },
      {
        scale: enableSpringAnimation
          ? withSpring(isActive.value ? 1 : 0, {
              damping: 10,
            })
          : 0,
      },
    ],
  }));

  return (
    <LineChartCursor type="crosshair" {...props}>
      <Animated.View
        {...crosshairWrapperProps}
        style={[
          {
            width: outerSize,
            height: outerSize,
            alignItems: 'center',
            justifyContent: 'center',
          },
          animatedCursorStyle,
          crosshairWrapperProps.style,
        ]}
      >
        <View
          {...crosshairOuterProps}
          style={[
            {
              backgroundColor: color,
              width: outerSize,
              height: outerSize,
              borderRadius: outerSize,
              opacity: 0.1,
              position: 'absolute',
            },
            crosshairOuterProps.style,
          ]}
        />
        <View
          {...crosshairProps}
          style={[
            {
              backgroundColor: color,
              width: size,
              height: size,
              borderRadius: size,
            },
            crosshairProps.style,
          ]}
        />
      </Animated.View>
      {children}
    </LineChartCursor>
  );
}

ImageTransformer = React.memo<ImageTransformerProps>(
  ({
    outerGestureHandlerRefs = [],
    source,
    width,
    height,
    onStateChange = workletNoop,
    renderImage,
    windowDimensions = Dimensions.get('window'),
    isActive,
    outerGestureHandlerActive,
    style,
    onTap = workletNoop,
    onDoubleTap = workletNoop,
    onInteraction = workletNoop,
    DOUBLE_TAP_SCALE = 3,
    MAX_SCALE = 3,
    MIN_SCALE = 0.7,
    OVER_SCALE = 0.5,
    timingConfig = defaultTimingConfig,
    springConfig = defaultSpringConfig,
    enabled = true,
    ImageComponent = Image,
  }) => {
    // fixGestureHandler();

    assertWorklet(onStateChange);
    assertWorklet(onTap);
    assertWorklet(onDoubleTap);
    assertWorklet(onInteraction);

    if (typeof source === 'undefined') {
      throw new Error(
        'ImageTransformer: either source or uri should be passed to display an image',
      );
    }

    const imageSource = useMemo(
      () =>
        typeof source === 'string'
          ? {
              uri: source,
            }
          : source,
      [source],
    );

    const interactionsEnabled = useSharedValue(false);
    const setInteractionsEnabled = useCallback((value: boolean) => {
      interactionsEnabled.value = value;
    }, []);
    const onLoadImageSuccess = useCallback(() => {
      setInteractionsEnabled(true);
    }, []);

    // HACK ALERT
    // we disable pinch handler in order to trigger onFinish
    // in case user releases one finger
    const [pinchEnabled, setPinchEnabledState] = useState(true);
    useEffect(() => {
      if (!pinchEnabled) {
        setPinchEnabledState(true);
      }
    }, [pinchEnabled]);
    const disablePinch = useCallback(() => {
      setPinchEnabledState(false);
    }, []);
    // HACK ALERT END

    const pinchRef = useRef(null);
    const panRef = useRef(null);
    const tapRef = useRef(null);
    const doubleTapRef = useRef(null);

    const panState = useSharedValue<State>(State.UNDETERMINED);
    const pinchState = useSharedValue<State>(State.UNDETERMINED);

    const scale = useSharedValue(1);
    const scaleOffset = useSharedValue(1);
    const translation = vectors.useSharedVector(0, 0);
    const panVelocity = vectors.useSharedVector(0, 0);
    const scaleTranslation = vectors.useSharedVector(0, 0);
    const offset = vectors.useSharedVector(0, 0);

    const canvas = useMemo(
      () =>
        vectors.create(
          windowDimensions.width,
          windowDimensions.height,
        ),
      [windowDimensions.width, windowDimensions.height],
    );
    const targetWidth = windowDimensions.width;
    const scaleFactor = width / targetWidth;
    const targetHeight = height / scaleFactor;
    const image = useMemo(
      () => vectors.create(targetWidth, targetHeight),
      [targetHeight, targetWidth],
    );

    const canPanVertically = useDerivedValue(() => {
      return windowDimensions.height < targetHeight * scale.value;
    }, []);

    const resetSharedState = useWorkletCallback(
      (animated?: boolean) => {
        'worklet';

        if (animated) {
          scale.value = withTiming(1, timingConfig);
          scaleOffset.value = 1;

          vectors.set(offset, () => withTiming(0, timingConfig));
        } else {
          scale.value = 1;
          scaleOffset.value = 1;
          vectors.set(translation, 0);
          vectors.set(scaleTranslation, 0);
          vectors.set(offset, 0);
        }
      },
      [timingConfig],
    );

    const maybeRunOnEnd = useWorkletCallback(() => {
      'worklet';

      const target = vectors.create(0, 0);

      const fixedScale = clamp(MIN_SCALE, scale.value, MAX_SCALE);
      const scaledImage = image.y * fixedScale;
      const rightBoundary = (canvas.x / 2) * (fixedScale - 1);

      let topBoundary = 0;

      if (canvas.y < scaledImage) {
        topBoundary = Math.abs(scaledImage - canvas.y) / 2;
      }

      const maxVector = vectors.create(rightBoundary, topBoundary);
      const minVector = vectors.invert(maxVector);

      if (!canPanVertically.value) {
        offset.y.value = withSpring(target.y, springConfig);
      }

      // we should handle this only if pan or pinch handlers has been used already
      if (
        (checkIsNotUsed(panState) || checkIsNotUsed(pinchState)) &&
        pinchState.value !== State.CANCELLED
      ) {
        return;
      }

      if (
        vectors.eq(offset, 0) &&
        vectors.eq(translation, 0) &&
        vectors.eq(scaleTranslation, 0) &&
        scale.value === 1
      ) {
        // we don't need to run any animations
        return;
      }

      if (scale.value <= 1) {
        // just center it
        vectors.set(offset, () => withTiming(0, timingConfig));
        return;
      }

      vectors.set(
        target,
        vectors.clamp(offset, minVector, maxVector),
      );

      const deceleration = 0.9915;

      const isInBoundaryX = target.x === offset.x.value;
      const isInBoundaryY = target.y === offset.y.value;

      if (isInBoundaryX) {
        if (
          Math.abs(panVelocity.x.value) > 0 &&
          scale.value <= MAX_SCALE
        ) {
          offset.x.value = withDecay({
            velocity: panVelocity.x.value,
            clamp: [minVector.x, maxVector.x],
            deceleration,
          });
        }
      } else {
        offset.x.value = withSpring(target.x, springConfig);
      }

      if (isInBoundaryY) {
        if (
          Math.abs(panVelocity.y.value) > 0 &&
          scale.value <= MAX_SCALE &&
          offset.y.value !== minVector.y &&
          offset.y.value !== maxVector.y
        ) {
          offset.y.value = withDecay({
            velocity: panVelocity.y.value,
            clamp: [minVector.y, maxVector.y],
            deceleration,
          });
        }
      } else {
        offset.y.value = withSpring(target.y, springConfig);
      }
    }, [
      MIN_SCALE,
      MAX_SCALE,
      image,
      canvas,
      springConfig,
      timingConfig,
    ]);

    const onPanEvent = useAnimatedGestureHandler<
      PanGestureHandlerGestureEvent,
      {
        panOffset: vectors.Vector<number>;
        pan: vectors.Vector<number>;
      }
    >({
      onInit: (_, ctx) => {
        ctx.panOffset = vectors.create(0, 0);
      },

      shouldHandleEvent: () => {
        return (
          scale.value > 1 &&
          (typeof outerGestureHandlerActive !== 'undefined'
            ? !outerGestureHandlerActive.value
            : true) &&
          interactionsEnabled.value
        );
      },

      beforeEach: (evt, ctx) => {
        ctx.pan = vectors.create(evt.translationX, evt.translationY);
        const velocity = vectors.create(evt.velocityX, evt.velocityY);

        vectors.set(panVelocity, velocity);
      },

      onStart: (_, ctx) => {
        cancelAnimation(offset.x);
        cancelAnimation(offset.y);
        ctx.panOffset = vectors.create(0, 0);
        onInteraction('pan');
      },

      onActive: (evt, ctx) => {
        panState.value = evt.state;

        if (scale.value > 1) {
          if (evt.numberOfPointers > 1) {
            // store pan offset during the pan with two fingers (during the pinch)
            vectors.set(ctx.panOffset, ctx.pan);
          } else {
            // subtract the offset and assign fixed pan
            const nextTranslate = vectors.add(
              ctx.pan,
              vectors.invert(ctx.panOffset),
            );
            translation.x.value = nextTranslate.x;

            if (canPanVertically.value) {
              translation.y.value = nextTranslate.y;
            }
          }
        }
      },

      onEnd: (evt, ctx) => {
        panState.value = evt.state;

        vectors.set(ctx.panOffset, 0);
        vectors.set(offset, vectors.add(offset, translation));
        vectors.set(translation, 0);

        maybeRunOnEnd();

        vectors.set(panVelocity, 0);
      },
    });

    useAnimatedReaction(
      () => {
        if (typeof isActive === 'undefined') {
          return true;
        }

        return isActive.value;
      },
      (currentActive) => {
        if (!currentActive) {
          resetSharedState();
        }
      },
    );

    const onScaleEvent = useAnimatedGestureHandler<
      PinchGestureHandlerGestureEvent,
      {
        origin: vectors.Vector<number>;
        adjustFocal: vectors.Vector<number>;
        gestureScale: number;
        nextScale: number;
      }
    >({
      onInit: (_, ctx) => {
        ctx.origin = vectors.create(0, 0);
        ctx.gestureScale = 1;
        ctx.adjustFocal = vectors.create(0, 0);
      },

      shouldHandleEvent: (evt) => {
        return (
          evt.numberOfPointers === 2 &&
          (typeof outerGestureHandlerActive !== 'undefined'
            ? !outerGestureHandlerActive.value
            : true) &&
          interactionsEnabled.value
        );
      },

      beforeEach: (evt, ctx) => {
        // calculate the overall scale value
        // also limits this.event.scale
        ctx.nextScale = clamp(
          evt.scale * scaleOffset.value,
          MIN_SCALE,
          MAX_SCALE + OVER_SCALE,
        );

        if (
          ctx.nextScale > MIN_SCALE &&
          ctx.nextScale < MAX_SCALE + OVER_SCALE
        ) {
          ctx.gestureScale = evt.scale;
        }

        // this is just to be able to use with vectors
        const focal = vectors.create(evt.focalX, evt.focalY);
        const CENTER = vectors.divide(canvas, 2);

        // since it works even when you release one finger
        if (evt.numberOfPointers === 2) {
          // focal with translate offset
          // it alow us to scale into different point even then we pan the image
          ctx.adjustFocal = vectors.sub(
            focal,
            vectors.add(CENTER, offset),
          );
        } else if (
          evt.state === State.ACTIVE &&
          evt.numberOfPointers !== 2
        ) {
          runOnJS(disablePinch)();
        }
      },

      afterEach: (evt, ctx) => {
        if (
          evt.state === State.END ||
          evt.state === State.CANCELLED
        ) {
          return;
        }

        scale.value = ctx.nextScale;
      },

      onStart: (_, ctx) => {
        onInteraction('scale');
        cancelAnimation(offset.x);
        cancelAnimation(offset.y);
        vectors.set(ctx.origin, ctx.adjustFocal);
      },

      onActive: (evt, ctx) => {
        pinchState.value = evt.state;

        const pinch = vectors.sub(ctx.adjustFocal, ctx.origin);

        const nextTranslation = vectors.add(
          pinch,
          ctx.origin,
          vectors.multiply(-1, ctx.gestureScale, ctx.origin),
        );

        vectors.set(scaleTranslation, nextTranslation);
      },

      onFinish: (evt, ctx) => {
        // reset gestureScale value
        ctx.gestureScale = 1;
        pinchState.value = evt.state;
        // store scale value
        scaleOffset.value = scale.value;

        vectors.set(offset, vectors.add(offset, scaleTranslation));
        vectors.set(scaleTranslation, 0);

        if (scaleOffset.value < 1) {
          // make sure we don't add stuff below the 1
          scaleOffset.value = 1;

          // this runs the timing animation
          scale.value = withTiming(1, timingConfig);
        } else if (scaleOffset.value > MAX_SCALE) {
          scaleOffset.value = MAX_SCALE;
          scale.value = withTiming(MAX_SCALE, timingConfig);
        }

        maybeRunOnEnd();
      },
    });

    const onTapEvent = useAnimatedGestureHandler({
      shouldHandleEvent: (evt) => {
        return (
          evt.numberOfPointers === 1 &&
          (typeof outerGestureHandlerActive !== 'undefined'
            ? !outerGestureHandlerActive.value
            : true) &&
          interactionsEnabled.value
        );
      },

      onStart: () => {
        cancelAnimation(offset.x);
        cancelAnimation(offset.y);
      },

      onActive: () => {
        onTap(scale.value > 1);
      },

      onEnd: () => {
        maybeRunOnEnd();
      },
    });

    const handleScaleTo = useWorkletCallback(
      (x: number, y: number) => {
        'worklet';

        scale.value = withTiming(DOUBLE_TAP_SCALE, timingConfig);
        scaleOffset.value = DOUBLE_TAP_SCALE;

        const targetImageSize = vectors.multiply(
          image,
          DOUBLE_TAP_SCALE,
        );

        const CENTER = vectors.divide(canvas, 2);
        const imageCenter = vectors.divide(image, 2);

        const focal = vectors.create(x, y);

        const origin = vectors.multiply(
          -1,
          vectors.sub(vectors.divide(targetImageSize, 2), CENTER),
        );

        const koef = vectors.sub(
          vectors.multiply(vectors.divide(1, imageCenter), focal),
          1,
        );

        const target = vectors.multiply(origin, koef);

        if (targetImageSize.y < canvas.y) {
          target.y = 0;
        }

        offset.x.value = withTiming(target.x, timingConfig);
        offset.y.value = withTiming(target.y, timingConfig);
      },
      [DOUBLE_TAP_SCALE, timingConfig, image, canvas],
    );

    const onDoubleTapEvent = useAnimatedGestureHandler<
      TapGestureHandlerGestureEvent,
      {}
    >({
      shouldHandleEvent: (evt) => {
        return (
          evt.numberOfPointers === 1 &&
          (typeof outerGestureHandlerActive !== 'undefined'
            ? !outerGestureHandlerActive.value
            : true) &&
          interactionsEnabled.value
        );
      },

      onActive: ({ x, y }) => {
        onDoubleTap(scale.value > 1);

        if (scale.value > 1) {
          resetSharedState(true);
        } else {
          handleScaleTo(x, y);
        }
      },
    });

    const animatedStyles = useAnimatedStyle<ViewStyle>(() => {
      const noOffset = offset.x.value === 0 && offset.y.value === 0;
      const noTranslation =
        translation.x.value === 0 && translation.y.value === 0;
      const noScaleTranslation =
        scaleTranslation.x.value === 0 &&
        scaleTranslation.y.value === 0;

      const isInactive =
        scale.value === 1 &&
        noOffset &&
        noTranslation &&
        noScaleTranslation;

      onStateChange(isInactive);

      return {
        transform: [
          {
            translateX:
              scaleTranslation.x.value +
              translation.x.value +
              offset.x.value,
          },
          {
            translateY:
              scaleTranslation.y.value +
              translation.y.value +
              offset.y.value,
          },
          { scale: scale.value },
        ],
      };
    }, []);

    return (
      <Animated.View
        style={[styles.container, { width: targetWidth }, style]}
      >
        <PinchGestureHandler
          enabled={enabled && pinchEnabled}
          ref={pinchRef}
          onGestureEvent={onScaleEvent}
          simultaneousHandlers={[
            panRef,
            tapRef,
            ...outerGestureHandlerRefs,
          ]}
        >
          <Animated.View style={styles.fill}>
            <PanGestureHandler
              enabled={enabled}
              ref={panRef}
              minDist={4}
              avgTouches
              simultaneousHandlers={[
                pinchRef,
                tapRef,
                ...outerGestureHandlerRefs,
              ]}
              onGestureEvent={onPanEvent}
            >
              <Animated.View style={styles.fill}>
                <TapGestureHandler
                  enabled={enabled}
                  ref={tapRef}
                  numberOfTaps={1}
                  maxDeltaX={8}
                  maxDeltaY={8}
                  simultaneousHandlers={[
                    pinchRef,
                    panRef,
                    ...outerGestureHandlerRefs,
                  ]}
                  waitFor={doubleTapRef}
                  onGestureEvent={onTapEvent}
                >
                  <Animated.View style={[styles.fill]}>
                    <Animated.View style={styles.fill}>
                      <Animated.View style={styles.wrapper}>
                        <TapGestureHandler
                          enabled={enabled}
                          ref={doubleTapRef}
                          numberOfTaps={2}
                          maxDelayMs={140}
                          maxDeltaX={16}
                          maxDeltaY={16}
                          simultaneousHandlers={[
                            pinchRef,
                            panRef,
                            ...outerGestureHandlerRefs,
                          ]}
                          onGestureEvent={onDoubleTapEvent}
                        >
                          <Animated.View style={animatedStyles}>
                            {typeof renderImage === 'function' ? (
                              renderImage({
                                source: imageSource,
                                width: targetWidth,
                                height: targetHeight,
                                onLoad: onLoadImageSuccess,
                              })
                            ) : (
                              <ImageComponent
                                onLoad={onLoadImageSuccess}
                                source={imageSource}
                                style={{
                                  width: targetWidth,
                                  height: targetHeight,
                                }}
                              />
                            )}
                          </Animated.View>
                        </TapGestureHandler>
                      </Animated.View>
                    </Animated.View>
                  </Animated.View>
                </TapGestureHandler>
              </Animated.View>
            </PanGestureHandler>
          </Animated.View>
        </PinchGestureHandler>
      </Animated.View>
    );
  },
)

Pager = typedMemo(function Pager<
  TPages,
  ItemT = UnpackItemT<TPages>,
>({
  pages,
  initialIndex,
  totalCount,
  numToRender = 2,
  onIndexChange = workletNoop,
  renderPage,
  width = dimensions.width,
  gutterWidth = GUTTER_WIDTH,
  shouldRenderGutter = true,
  keyExtractor,
  pagerWrapperStyles = {},
  getItem,
  springConfig,
  onPagerTranslateChange = workletNoop,
  onGesture = workletNoop,
  onEnabledGesture = workletNoop,
  shouldHandleGestureEvent = workletNoopTrue,
  initialDiffValue = 0,
  shouldUseInteractionManager = true,
  outerGestureHandlerRefs = [],
  verticallyEnabled = true,
}: PagerProps<TPages, ItemT>) {
  assertWorklet(onIndexChange);
  assertWorklet(onPagerTranslateChange);
  assertWorklet(onGesture);
  assertWorklet(onEnabledGesture);
  assertWorklet(shouldHandleGestureEvent);

  // make sure to not calculate translate with gutter
  // if we don't want to render it
  if (!shouldRenderGutter) {
    gutterWidth = 0;
  }

  const getPageTranslate = useWorkletCallback(
    (i: number) => {
      const t = i * width;
      const g = gutterWidth * i;
      return -(t + g);
    },
    [gutterWidth, width],
  );

  const pagerRef = useRef(null);
  const tapRef = useRef(null);

  const isActive = useSharedValue(true);

  const onPageStateChange = useWorkletCallback((value: boolean) => {
    isActive.value = value;
  }, []);

  const velocity = useSharedValue(0);
  const isMounted = useRef(false);

  const [diffValue, setDiffValue] = useState(initialDiffValue);
  useEffect(() => {
    if (shouldUseInteractionManager && !isMounted.current) {
      InteractionManager.runAfterInteractions(() => {
        setDiffValue(numToRender);
        console.log('numToRender in interaction');
      });
      isMounted.current = true;
    } else {
      setDiffValue(numToRender);
    }
  }, [numToRender]);

  // S2: Pager related stuff
  const [activeIndex, setActiveIndex] = useState(initialIndex);

  const index = useSharedValue(initialIndex);
  const length = useSharedValue(totalCount);
  const pagerX = useSharedValue(0);
  const toValueAnimation = useSharedValue(
    getPageTranslate(initialIndex),
  );

  const offsetX = useSharedValue(getPageTranslate(initialIndex));

  const totalWidth = useDerivedValue(() => {
    return length.value * width + gutterWidth * length.value - 2;
  }, []);

  const onIndexChangeCb = useWorkletCallback((nextIndex: number) => {
    onIndexChange(nextIndex);

    runOnJS(setActiveIndex)(nextIndex);
  }, []);

  const onIndexChangeWorklet = useWorkletCallback((i: number) => {
    offsetX.value = getPageTranslate(i);
    index.value = i;
    onIndexChangeCb(i);
  }, []);

  useEffect(() => {
    runOnUI(onIndexChangeWorklet)(initialIndex);
  }, [initialIndex]);

  const getSpringConfig = useWorkletCallback(
    (noVelocity?: boolean) => {
      const ratio = 1.1;
      const mass = 0.4;
      const stiffness = IS_ANDROID ? 200.0 : 100.0;
      const damping = ratio * 2.0 * Math.sqrt(mass * stiffness);

      const configToUse =
        typeof springConfig !== 'undefined'
          ? springConfig
          : {
              stiffness,
              mass,
              damping,
              restDisplacementThreshold: 1,
              restSpeedThreshold: 5,
            };

      // @ts-ignore
      // cannot use merge and spread here :(
      configToUse.velocity = noVelocity ? 0 : velocity.value;

      return configToUse;
    },
    [springConfig],
  );

  const onChangePageAnimation = useWorkletCallback(
    (noVelocity?: boolean) => {
      const config = getSpringConfig(noVelocity);

      if (offsetX.value === toValueAnimation.value) {
        return;
      }

      offsetX.value = withSpring(
        toValueAnimation.value,
        config,
        (isCanceled) => {
          if (!isCanceled) {
            velocity.value = 0;
          }
        },
      );
    },
    [getSpringConfig],
  );

  // S3 Pager
  const getCanSwipe = useWorkletCallback(
    (currentTranslate: number = 0) => {
      const nextTranslate = offsetX.value + currentTranslate;

      if (nextTranslate > 0) {
        return false;
      }

      const totalTranslate =
        width * (length.value - 1) + gutterWidth * (length.value - 1);

      if (Math.abs(nextTranslate) >= totalTranslate) {
        return false;
      }

      return true;
    },
    [width, gutterWidth],
  );

  const getNextIndex = useWorkletCallback(
    (v: number) => {
      const currentTranslate = Math.abs(
        getPageTranslate(index.value),
      );
      const currentIndex = index.value;
      const currentOffset = Math.abs(offsetX.value);

      const nextIndex = v < 0 ? currentIndex + 1 : currentIndex - 1;

      if (
        nextIndex < currentIndex &&
        currentOffset > currentTranslate
      ) {
        return currentIndex;
      }

      if (
        nextIndex > currentIndex &&
        currentOffset < currentTranslate
      ) {
        return currentIndex;
      }

      if (nextIndex > length.value - 1 || nextIndex < 0) {
        return currentIndex;
      }

      return nextIndex;
    },
    [getPageTranslate],
  );

  const isPagerInProgress = useDerivedValue(() => {
    return (
      Math.floor(Math.abs(getPageTranslate(index.value))) !==
      Math.floor(Math.abs(offsetX.value + pagerX.value))
    );
  }, [getPageTranslate]);

  const onPan = useAnimatedGestureHandler<
    PanGestureHandlerGestureEvent,
    {
      pagerActive: boolean;
      offsetX: null | number;
    }
  >({
    onGesture: (evt) => {
      onGesture(evt, isActive);

      if (isActive.value && !isPagerInProgress.value) {
        onEnabledGesture(evt);
      }
    },

    onInit: (_, ctx) => {
      ctx.offsetX = null;
    },

    shouldHandleEvent: (evt) => {
      return (
        (evt.numberOfPointers === 1 &&
          isActive.value &&
          Math.abs(evt.velocityX) > Math.abs(evt.velocityY) &&
          shouldHandleGestureEvent(evt)) ||
        isPagerInProgress.value
      );
    },

    onEvent: (evt) => {
      velocity.value = clampVelocity(
        evt.velocityX,
        MIN_VELOCITY,
        MAX_VELOCITY,
      );
    },

    onStart: (_, ctx) => {
      ctx.offsetX = null;
    },

    onActive: (evt, ctx) => {
      // workaround alert
      // the event triggers with a delay and first frame value jumps
      // we capture that value and subtract from the actual one
      // so the translate happens on a second frame
      if (ctx.offsetX === null) {
        ctx.offsetX =
          evt.translationX < 0 ? evt.translationX : -evt.translationX;
      }

      const val = evt.translationX - ctx.offsetX;

      const canSwipe = getCanSwipe(val);
      pagerX.value = canSwipe ? val : friction(val);
    },

    onEnd: (evt, ctx) => {
      const val = evt.translationX - ctx.offsetX!;

      const canSwipe = getCanSwipe(val);

      offsetX.value += pagerX.value;
      pagerX.value = 0;

      const nextIndex = getNextIndex(evt.velocityX);

      const vx = Math.abs(evt.velocityX);

      const translation = Math.abs(val);
      const isHalf = width / 2 < translation;

      const shouldMoveToNextPage = (vx > 10 || isHalf) && canSwipe;

      // we invert the value since the translationY is left to right
      toValueAnimation.value = -(shouldMoveToNextPage
        ? -getPageTranslate(nextIndex)
        : -getPageTranslate(index.value));

      onChangePageAnimation(!shouldMoveToNextPage);

      if (shouldMoveToNextPage) {
        index.value = nextIndex;
        onIndexChangeCb(nextIndex);
      }
    },
  });

  const onTap = useAnimatedGestureHandler({
    shouldHandleEvent: (evt) => {
      return evt.numberOfPointers === 1 && isActive.value;
    },

    onStart: () => {
      cancelAnimation(offsetX);
    },

    onEnd: () => {
      onChangePageAnimation(true);
    },
  });

  const pagerStyles = useAnimatedStyle<ViewStyle>(() => {
    const translateX = pagerX.value + offsetX.value;

    onPagerTranslateChange(translateX);

    return {
      width: totalWidth.value,
      transform: [
        {
          translateX,
        },
      ],
    };
  }, []);

  const pagerRefs = useMemo<PageRefs>(() => [pagerRef, tapRef], []);

  const pagesToRender = useMemo(() => {
    const temp = [];

    for (let i = 0; i < totalCount; i += 1) {
      let itemToUse;

      if (typeof getItem === 'function') {
        itemToUse = getItem(pages, i);
      } else if (Array.isArray(pages)) {
        itemToUse = pages[i];
      } else {
        throw new Error(
          'Pager: items either should be an array of getItem should be defined',
        );
      }

      const shouldRender = getShouldRender(i, activeIndex, diffValue);

      if (!shouldRender) {
        temp.push(null);
      } else {
        temp.push(
          <Page
            key={keyExtractor(itemToUse, i)}
            item={itemToUse}
            currentIndex={index}
            pagerRefs={pagerRefs}
            onPageStateChange={onPageStateChange}
            index={i}
            length={totalCount}
            gutterWidth={gutterWidth}
            renderPage={renderPage}
            getPageTranslate={getPageTranslate}
            width={width}
            isPagerInProgress={isPagerInProgress}
            shouldRenderGutter={shouldRenderGutter}
          />,
        );
      }
    }

    return temp;
  }, [
    activeIndex,
    diffValue,
    keyExtractor,
    getItem,
    totalCount,
    pages,
    getShouldRender,
    index,
    pagerRefs,
    onPageStateChange,
    gutterWidth,
    renderPage,
    getPageTranslate,
    width,
    isPagerInProgress,
    shouldRenderGutter,
  ]);

  return (
    <View style={StyleSheet.absoluteFillObject}>
      <Animated.View style={[StyleSheet.absoluteFill]}>
        <PanGestureHandler
          ref={pagerRef}
          minDist={0.1}
          minVelocityX={0.1}
          activeOffsetX={[-4, 4]}
          activeOffsetY={verticallyEnabled ? [-4, 4] : undefined}
          simultaneousHandlers={[tapRef, ...outerGestureHandlerRefs]}
          onGestureEvent={onPan}
        >
          <Animated.View style={StyleSheet.absoluteFill}>
            <TapGestureHandler
              ref={tapRef}
              maxDeltaX={10}
              maxDeltaY={10}
              simultaneousHandlers={pagerRef}
              onGestureEvent={onTap}
            >
              <Animated.View
                style={[StyleSheet.absoluteFill, pagerWrapperStyles]}
              >
                <Animated.View style={StyleSheet.absoluteFill}>
                  <Animated.View style={[styles.pager, pagerStyles]}>
                    {pagesToRender}
                  </Animated.View>
                </Animated.View>
              </Animated.View>
            </TapGestureHandler>
          </Animated.View>
        </PanGestureHandler>
      </Animated.View>
    </View>
  );
})