src/utils/input.js

/*
 * OS.js - JavaScript Cloud/Web Desktop Platform
 *
 * Copyright (c) Anders Evenrud <andersevenrud@gmail.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * @author  Anders Evenrud <andersevenrud@gmail.com>
 * @license Simplified BSD License
 */

const modifierNames =  ['ctrl', 'shift', 'alt', 'meta'];

/**
 * @typedef {Object} NormalizedEventPosition
 * @property {number} clientX
 * @property {number} clientY
 * @property {boolean} touch
 * @property {Element} target
 */

/**
 * Checks if keycombo matches
 * @param {string} combo Key combo
 * @param {Event} ev Event
 * @return {boolean}
 */
export const matchKeyCombo = (combo, ev) => {
  const checkKeys = String(combo).toLowerCase().split('+');
  const keyName = String(ev.key).toLowerCase();
  const validKeypress = checkKeys.every(k => modifierNames.indexOf(k) !== -1
    ? ev[k + 'Key']
    : keyName === k);

  return validKeypress;
};

/**
 * Normalizes event input (position)
 * @param {Event} ev Event
 * @return {NormalizedEventPosition}
 */
export const getEvent = (ev) => {
  let {clientX, clientY, target} = ev;
  const touch = ev.touches || ev.changedTouches || [];

  if (touch.length) {
    clientX = touch[0].clientX;
    clientY = touch[0].clientY;
  }

  return {clientX, clientY, touch: touch.length > 0, target};
};

/**
 * Creates a double-tap event handler
 * @param {number} [timeout=250] Timeout
 * @return {Function} Handler with => (ev, cb)
 */
export const doubleTap = (timeout = 250) => {
  let tapped = false;
  let timer;

  return (ev, cb) => {
    timer = clearTimeout(timer);
    timer = setTimeout(() => (tapped = false), timeout);

    if (tapped) {
      ev.preventDefault();
      return cb(ev);
    }

    tapped = true;

    return false;
  };
};