react-native-ui-lib/src/incubator/WheelPicker/usePresenter.js

<p align="center"> <img src="https://user-images.githubusercontent.com/1780255/105469025-56759000-5ca0-11eb-993d-3568c1fd54f4.png" height="250px" style="display:block"/> </p> <p align="center">UI Toolset & Components Library for React Native</p> <p a

import _ from 'lodash';
import React from 'react';
import useMiddleIndex from "./helpers/useListMiddleIndex";

const usePresenter = ({
  initialValue = 0,
  children,
  items: propItems,
  itemHeight,
  preferredNumVisibleRows
}) => {
  const extractItemsFromChildren = () => {
    const items = React.Children.map(children, child => {
      const childAsType = {
        value: child?.props.value,
        label: child?.props.label
      };
      return childAsType;
    });
    return items || [];
  };

  const items = children ? extractItemsFromChildren() : propItems || [];
  const middleIndex = useMiddleIndex({
    itemHeight,
    listSize: items.length
  });

  const getSelectedValueIndex = () => {
    if (_.isString(initialValue) || _.isNumber(initialValue)) {
      return _.findIndex(items, {
        value: initialValue
      });
    }

    return _.findIndex(items, {
      value: initialValue?.value
    });
  };

  const getRowItemAtOffset = offset => {
    const index = middleIndex(offset);
    const value = items[index].value;
    return {
      index,
      value
    };
  };

  return {
    index: getSelectedValueIndex(),
    items,
    height: itemHeight * preferredNumVisibleRows,
    getRowItemAtOffset
  };
};

export default usePresenter;