gesture-event-listeners.js

/**
@license
Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
Code distributed by Google as part of the polymer project is also
subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
*/
import '../utils/boot.js';

import { dedupingMixin } from '../utils/mixin.js';
import { addListener, removeListener } from '../utils/gestures.js';

/**
 * Element class mixin that provides API for adding Polymer's cross-platform
 * gesture events to nodes.
 *
 * The API is designed to be compatible with override points implemented
 * in `TemplateStamp` such that declarative event listeners in
 * templates will support gesture events when this mixin is applied along with
 * `TemplateStamp`.
 *
 * @mixinFunction
 * @polymer
 * @summary Element class mixin that provides API for adding Polymer's
 *   cross-platform gesture events to nodes
 * @template T
 * @param {function(new:T)} superClass Class to apply mixin to.
 * @return {function(new:T)} superClass with mixin applied.
 */
export const GestureEventListeners = dedupingMixin((superClass) => {
  /**
   * @polymer
   * @mixinClass
   * @implements {Polymer_GestureEventListeners}
   */
  class GestureEventListeners extends superClass {
    /**
     * Add the event listener to the node if it is a gestures event.
     *
     * @param {!EventTarget} node Node to add event listener to
     * @param {string} eventName Name of event
     * @param {function(!Event):void} handler Listener function to add
     * @return {void}
     * @override
     */
    _addEventListenerToNode(node, eventName, handler) {
      if (!addListener(node, eventName, handler)) {
        super._addEventListenerToNode(node, eventName, handler);
      }
    }

    /**
     * Remove the event listener to the node if it is a gestures event.
     *
     * @param {!EventTarget} node Node to remove event listener from
     * @param {string} eventName Name of event
     * @param {function(!Event):void} handler Listener function to remove
     * @return {void}
     * @override
     */
    _removeEventListenerFromNode(node, eventName, handler) {
      if (!removeListener(node, eventName, handler)) {
        super._removeEventListenerFromNode(node, eventName, handler);
      }
    }
  }

  return GestureEventListeners;
});