polygerrit-ui/app/elements/shared/gr-dropdown-list/gr-dropdown-list.js

/**
 * @license
 * Copyright (C) 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import '../../../scripts/bundled-polymer.js';

import '@polymer/iron-dropdown/iron-dropdown.js';
import '@polymer/paper-item/paper-item.js';
import '@polymer/paper-listbox/paper-listbox.js';
import '../../../styles/shared-styles.js';
import '../gr-button/gr-button.js';
import '../gr-date-formatter/gr-date-formatter.js';
import '../gr-select/gr-select.js';
import {GestureEventListeners} from '@polymer/polymer/lib/mixins/gesture-event-listeners.js';
import {LegacyElementMixin} from '@polymer/polymer/lib/legacy/legacy-element-mixin.js';
import {PolymerElement} from '@polymer/polymer/polymer-element.js';
import {htmlTemplate} from './gr-dropdown-list_html.js';

/**
 * fired when the selected value of the dropdown changes
 *
 * @event {change}
 */

const Defs = {};

/**
 * Requred values are text and value. mobileText and triggerText will
 * fall back to text if not provided.
 *
 * If bottomText is not provided, nothing will display on the second
 * line.
 *
 * If date is not provided, nothing will be displayed in its place.
 *
 * @typedef {{
 *    text: string,
 *    value: (string|number),
 *    bottomText: (string|undefined),
 *    triggerText: (string|undefined),
 *    mobileText: (string|undefined),
 *    date: (!Date|undefined),
 * }}
 */
Defs.item;

/** @extends Polymer.Element */
class GrDropdownList extends GestureEventListeners(
    LegacyElementMixin(
        PolymerElement)) {
  static get template() { return htmlTemplate; }

  static get is() { return 'gr-dropdown-list'; }
  /**
   * Fired when the selected value changes
   *
   * @event value-change
   *
   * @property {string|number} value
   */

  static get properties() {
    return {
      initialCount: Number,
      /** @type {!Array<!Defs.item>} */
      items: Object,
      text: String,
      disabled: {
        type: Boolean,
        value: false,
      },
      value: {
        type: String,
        notify: true,
      },
    };
  }

  static get observers() {
    return [
      '_handleValueChange(value, items)',
    ];
  }

  /**
   * Handle a click on the iron-dropdown element.
   *
   * @param {!Event} e
   */
  _handleDropdownClick(e) {
    // async is needed so that that the click event is fired before the
    // dropdown closes (This was a bug for touch devices).
    this.async(() => {
      this.$.dropdown.close();
    }, 1);
  }

  /**
   * Handle a click on the button to open the dropdown.
   *
   * @param {!Event} e
   */
  _showDropdownTapHandler(e) {
    this._open();
  }

  /**
   * Open the dropdown.
   */
  _open() {
    this.$.dropdown.open();
  }

  _computeMobileText(item) {
    return item.mobileText ? item.mobileText : item.text;
  }

  _handleValueChange(value, items) {
    // Polymer 2: check for undefined
    if ([value, items].some(arg => arg === undefined)) {
      return;
    }

    if (!value) { return; }
    const selectedObj = items.find(item => item.value + '' === value + '');
    if (!selectedObj) { return; }
    this.text = selectedObj.triggerText? selectedObj.triggerText :
      selectedObj.text;
    this.dispatchEvent(new CustomEvent('value-change', {
      detail: {value},
      bubbles: false,
    }));
  }
}

customElements.define(GrDropdownList.is, GrDropdownList);