chromium/third_party/google-closure-library/closure/goog/labs/events/touch.js

/**
 * @license
 * Copyright The Closure Library Authors.
 * SPDX-License-Identifier: Apache-2.0
 */

/**
 * @fileoverview Utilities to abstract mouse and touch events.
 */


goog.provide('goog.labs.events.touch');
goog.provide('goog.labs.events.touch.TouchData');

goog.require('goog.array');
goog.require('goog.asserts');
goog.require('goog.events.EventType');
goog.require('goog.string');


/**
 * Description the geometry and target of an event.
 *
 * @typedef {{
 *   clientX: number,
 *   clientY: number,
 *   screenX: number,
 *   screenY: number,
 *   target: EventTarget
 * }}
 */
goog.labs.events.touch.TouchData;


/**
 * Takes a mouse or touch event and returns the relevant geometry and target
 * data.
 * @param {!Event} e A mouse or touch event.
 * @return {!goog.labs.events.touch.TouchData}
 */
goog.labs.events.touch.getTouchData = function(e) {
  'use strict';
  let source = e;
  goog.asserts.assert(
      goog.string.startsWith(e.type, 'touch') ||
          goog.string.startsWith(e.type, 'mouse'),
      'Event must be mouse or touch event.');

  if (goog.string.startsWith(e.type, 'touch')) {
    goog.asserts.assert(
        goog.array.contains(
            [
              goog.events.EventType.TOUCHCANCEL, goog.events.EventType.TOUCHEND,
              goog.events.EventType.TOUCHMOVE, goog.events.EventType.TOUCHSTART
            ],
            e.type),
        'Touch event not of valid type.');

    // If the event is end or cancel, take the first changed touch,
    // otherwise the first target touch.
    source = (e.type == goog.events.EventType.TOUCHEND ||
              e.type == goog.events.EventType.TOUCHCANCEL) ?
        e.changedTouches[0] :
        e.targetTouches[0];
  }

  return {
    clientX: source['clientX'],
    clientY: source['clientY'],
    screenX: source['screenX'],
    screenY: source['screenY'],
    target: source['target']
  };
};