react-native-reanimated/src/reanimated2/hook/useAnimatedRef.ts

More powerful alternative to Animated library for React Native.

import type { Component } from 'react';
import { useRef } from 'react';
import { useSharedValue } from './useSharedValue';
import type { AnimatedRef, RefObjectFunction } from './commonTypes';
import type { ShadowNodeWrapper } from '../commonTypes';
import { getShadowNodeWrapperFromRef } from '../fabricUtils';
import {
  makeShareableCloneRecursive,
  registerShareableMapping,
} from '../shareables';
import { findNodeHandle } from 'react-native';

interface ComponentRef extends Component {
  getNativeScrollRef?: () => ComponentRef;
  getScrollableNode?: () => ComponentRef;
}

function getComponentOrScrollableRef(component: ComponentRef): ComponentRef {
  if (global._IS_FABRIC && component.getNativeScrollRef) {
    return component.getNativeScrollRef();
  } else if (!global._IS_FABRIC && component.getScrollableNode) {
    return component.getScrollableNode();
  }
  return component;
}

const getTagValueFunction = global._IS_FABRIC
  ? getShadowNodeWrapperFromRef
  : findNodeHandle;

export function useAnimatedRef<T extends ComponentRef>(): AnimatedRef<T> {
  const tag = useSharedValue<number | ShadowNodeWrapper | null>(-1);
  const ref = useRef<RefObjectFunction<T>>();

  if (!ref.current) {
    const fun: RefObjectFunction<T> = <RefObjectFunction<T>>((component) => {
      // enters when ref is set by attaching to a component
      if (component) {
        tag.value = getTagValueFunction(getComponentOrScrollableRef(component));
        fun.current = component;
      }
      return tag.value;
    });

    fun.current = null;

    const remoteRef = makeShareableCloneRecursive({
      __init: () => {
        'worklet';
        return () => tag.value;
      },
    });
    registerShareableMapping(fun, remoteRef);
    ref.current = fun;
  }

  return ref.current;
}