@kietpt2003/react-native-core-ui/dist/hooks/DraggableFlatList/useNestedAutoScroll.js

React Native Core UI components by KietPT

import { runOnJS, useAnimatedReaction, useDerivedValue, useSharedValue, } from "react-native-reanimated";
import { SCROLL_POSITION_TOLERANCE } from "../../constants/DraggableFlatList/constants";
import { useSafeNestableScrollContainerContext } from "../../context/DraggableFlatList/nestableScrollContainerContext";
// This is mostly copied over from the main react-native-draggable-flatlist
// useAutoScroll hook with a few notable exceptions:
// - Since animated values are now coming in via a callback,
//   we won't guarantee they exist (and default them if not).
// - Outer scrollable is a ScrollView, not a FlatList
// TODO: see if we can combine into a single shared `useAutoScroll()` hook
export function useNestedAutoScroll(params) {
    const { outerScrollOffset, containerSize, scrollableRef, scrollViewSize, } = useSafeNestableScrollContainerContext();
    const DUMMY_VAL = useSharedValue(0);
    const { hoverOffset = DUMMY_VAL, activeCellSize = DUMMY_VAL, autoscrollSpeed = 100, autoscrollThreshold = 30, isDraggingCell = DUMMY_VAL, isTouchActiveNative = DUMMY_VAL, } = params;
    const hoverScreenOffset = useDerivedValue(() => {
        return hoverOffset.value - outerScrollOffset.value;
    }, []);
    const isScrolledUp = useDerivedValue(() => {
        return outerScrollOffset.value - SCROLL_POSITION_TOLERANCE <= 0;
    }, []);
    const isScrolledDown = useDerivedValue(() => {
        return (outerScrollOffset.value + containerSize.value + SCROLL_POSITION_TOLERANCE >=
            scrollViewSize.value);
    }, []);
    const distToTopEdge = useDerivedValue(() => {
        return Math.max(0, hoverScreenOffset.value);
    }, [hoverScreenOffset]);
    const distToBottomEdge = useDerivedValue(() => {
        const dist = containerSize.value - (hoverScreenOffset.value + activeCellSize.value);
        return Math.max(0, dist);
    }, [hoverScreenOffset, activeCellSize, containerSize]);
    const isAtTopEdge = useDerivedValue(() => {
        return distToTopEdge.value <= autoscrollThreshold;
    }, []);
    const isAtBottomEdge = useDerivedValue(() => {
        return distToBottomEdge.value <= autoscrollThreshold;
    });
    const scrollTarget = useSharedValue(0);
    useAnimatedReaction(() => {
        return isDraggingCell.value;
    }, (cur, prev) => {
        if (cur && !prev) {
            scrollTarget.value = outerScrollOffset.value;
        }
    }, [activeCellSize]);
    function scrollToInternal(y) {
        var _a;
        (_a = scrollableRef.current) === null || _a === void 0 ? void 0 : _a.scrollTo({ y, animated: true });
    }
    useDerivedValue(() => {
        const isAtEdge = isAtTopEdge.value || isAtBottomEdge.value;
        const topDisabled = isAtTopEdge.value && isScrolledUp.value;
        const bottomDisabled = isAtBottomEdge.value && isScrolledDown.value;
        const isEdgeDisabled = topDisabled || bottomDisabled;
        const scrollTargetDiff = Math.abs(scrollTarget.value - outerScrollOffset.value);
        const scrollInProgress = scrollTargetDiff > SCROLL_POSITION_TOLERANCE;
        const shouldScroll = isAtEdge &&
            !isEdgeDisabled &&
            isDraggingCell.value &&
            isTouchActiveNative.value &&
            !scrollInProgress;
        const distFromEdge = isAtTopEdge.value
            ? distToTopEdge.value
            : distToBottomEdge.value;
        const speedPct = 1 - distFromEdge / autoscrollThreshold;
        const offset = speedPct * autoscrollSpeed;
        const targetOffset = isAtTopEdge.value
            ? Math.max(0, outerScrollOffset.value - offset)
            : outerScrollOffset.value + offset;
        if (shouldScroll) {
            scrollTarget.value = targetOffset;
            // Reanimated scrollTo is crashing on android. use 'regular' scrollTo until figured out.
            // scrollTo(scrollViewRef, 0, scrollTarget.value, true)
            runOnJS(scrollToInternal)(targetOffset);
        }
    }, [autoscrollSpeed, autoscrollThreshold, isDraggingCell]);
    return null;
}