react-flexigrid/lib/dom/WheelHandler.js

A React table component designed to allow presenting millions of rows of data.

import _classCallCheck from 'babel-runtime/helpers/classCallCheck';
import { requestAnimationFrame, getJudgeFunction } from '../utils';
import normalizeWheel from './normalizeWheel';

var WheelHandler =
/**
 * onWheel is the callback that will be called with right frame rate if
 * any wheel events happened
 * onWheel should is to be called with two arguments: deltaX and deltaY in
 * this order
 */
function WheelHandler(onWheel, handleScrollX, handleScrollY, stopPropagation) {
  _classCallCheck(this, WheelHandler);

  _initialiseProps.call(this);

  this.deltaX = 0;
  this.deltaY = 0;
  this.animationFrameID = null;

  this.handleScrollX = getJudgeFunction(handleScrollX);
  this.handleScrollY = getJudgeFunction(handleScrollY);
  this.stopPropagation = getJudgeFunction(stopPropagation);
  this.callback = onWheel;
};

var _initialiseProps = function _initialiseProps() {
  var _this = this;

  this.onWheel = function (e) {
    var normalizedEvent = normalizeWheel(e);
    var pixelX = normalizedEvent.pixelX,
        pixelY = normalizedEvent.pixelY;

    var deltaX = _this.deltaX + pixelX;
    var deltaY = _this.deltaY + pixelY;
    var handleScrollX = _this.handleScrollX(deltaX, deltaY);
    var handleScrollY = _this.handleScrollY(deltaY, deltaX);
    if (!handleScrollX && !handleScrollY) {
      return;
    }

    _this.deltaX += handleScrollX ? pixelX : 0;
    _this.deltaY += handleScrollY ? pixelY : 0;

    e.preventDefault();

    var changed = void 0;
    if (_this.deltaX !== 0 || _this.deltaY !== 0) {
      if (_this.stopPropagation()) {
        e.stopPropagation();
      }
      changed = true;
    }

    if (changed === true && _this.animationFrameID === null) {
      _this.animationFrameID = requestAnimationFrame(_this.didWheel);
    }
  };

  this.didWheel = function () {
    _this.animationFrameID = null;
    if (_this.callback) {
      _this.callback(_this.deltaX, _this.deltaY);
    }
    _this.deltaX = 0;
    _this.deltaY = 0;
  };
};

export default WheelHandler;