react-selectable-box/es/hooks/useScroll.js

A React component used hooks that allows you to select elements in the drag area using the mouse

import { useEffect, useRef } from 'react';
import { getClientXY } from "../utils";
var DEFAULT_SCROLL_SPEED = 4;
var EDGE_OFFSET = 1;
export default function useScroll() {
  var scrollSpeed = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : DEFAULT_SCROLL_SPEED;
  var topRaf = useRef(null);
  var bottomRaf = useRef(null);
  var leftRaf = useRef(null);
  var rightRaf = useRef(null);
  var cancelRaf = function cancelRaf(raf) {
    if (raf.current) {
      cancelAnimationFrame(raf.current);
      raf.current = null;
    }
  };
  var cancelScroll = function cancelScroll() {
    cancelRaf(topRaf);
    cancelRaf(bottomRaf);
    cancelRaf(leftRaf);
    cancelRaf(rightRaf);
  };
  useEffect(function () {
    return cancelScroll;
  }, []);
  var smoothScroll = function smoothScroll(e, _container) {
    var container = _container === document.body ? document.documentElement : _container;
    var _getClientXY = getClientXY(e),
      clientX = _getClientXY.clientX,
      clientY = _getClientXY.clientY;

    // top
    if (clientY - EDGE_OFFSET <= 0 || clientY <= container.getBoundingClientRect().top) {
      if (!topRaf.current) {
        var callback = function callback() {
          if (container.scrollTop > 0) {
            topRaf.current = requestAnimationFrame(function () {
              container.scrollTop -= scrollSpeed;
              callback();
            });
          }
        };
        callback();
      }
    } else {
      cancelRaf(topRaf);
    }

    // bottom
    if (clientY + EDGE_OFFSET >= window.innerHeight || clientY >= container.getBoundingClientRect().bottom) {
      if (!bottomRaf.current) {
        var _callback = function _callback() {
          if (container.scrollTop < container.scrollHeight - container.clientHeight) {
            bottomRaf.current = requestAnimationFrame(function () {
              container.scrollTop += scrollSpeed;
              _callback();
            });
          }
        };
        _callback();
      }
    } else {
      cancelRaf(bottomRaf);
    }

    // left
    if (clientX - EDGE_OFFSET <= 0 || clientX <= container.getBoundingClientRect().left) {
      if (!leftRaf.current) {
        var _callback2 = function _callback2() {
          if (container.scrollLeft > 0) {
            leftRaf.current = requestAnimationFrame(function () {
              container.scrollLeft -= scrollSpeed;
              _callback2();
            });
          }
        };
        _callback2();
      }
    } else {
      cancelRaf(leftRaf);
    }

    // right
    if (clientX + EDGE_OFFSET >= window.innerWidth || clientX >= container.getBoundingClientRect().right) {
      if (!rightRaf.current) {
        var _callback3 = function _callback3() {
          if (container.scrollLeft < container.scrollWidth - container.clientWidth) {
            rightRaf.current = requestAnimationFrame(function () {
              container.scrollLeft += scrollSpeed;
              _callback3();
            });
          }
        };
        _callback3();
      }
    } else {
      cancelRaf(rightRaf);
    }
  };
  return {
    cancelScroll: cancelScroll,
    smoothScroll: smoothScroll
  };
}