ui_utils.js

/**
 * @license
 * Copyright 2016 Google Inc.
 *
 * 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.
 */


goog.provide('shaka.ui.Utils');

goog.require('goog.asserts');


shaka.ui.Utils = class {
  /**
   * @param {!HTMLElement} element
   * @param {string} className
   * @return {!HTMLElement}
   */
  // TODO: This can be replaced by shaka.util.Dom.getElementByClassName
  static getFirstDescendantWithClassName(element, className) {
    const descendant = shaka.ui.Utils.getDescendantIfExists(element, className);
    goog.asserts.assert(descendant != null, 'Should not be null!');

    return descendant;
  }


  /**
   * @param {!HTMLElement} element
   * @param {string} className
   * @return {?HTMLElement}
   */
  static getDescendantIfExists(element, className) {
    const childrenWithClassName = element.getElementsByClassName(className);
    if (childrenWithClassName.length) {
      return /** @type {!HTMLElement} */ (childrenWithClassName[0]);
    }

    return null;
  }


  /**
   * Finds a descendant of |menu| that has a 'shaka-chosen-item' class
   * and focuses on its' parent.
   *
   * @param {HTMLElement} menu
   */
  static focusOnTheChosenItem(menu) {
    if (!menu) {
      return;
    }
    const chosenItem = shaka.ui.Utils.getDescendantIfExists(
        menu, 'shaka-chosen-item');
    if (chosenItem) {
      chosenItem.parentElement.focus();
    }
  }


  /**
   * @return {!Element}
   */
  static checkmarkIcon() {
    const icon = shaka.util.Dom.createHTMLElement('i');
    icon.classList.add('material-icons');
    icon.classList.add('shaka-chosen-item');
    icon.textContent = shaka.ui.Enums.MaterialDesignIcons.CHECKMARK;
    // Screen reader should ignore icon text.
    icon.setAttribute('aria-hidden', 'true');
    return icon;
  }


  /**
   * Depending on the value of display, sets/removes the css class of element to
   * either display it or hide it.
   *
   * @param {Element} element
   * @param {boolean} display
   */
  static setDisplay(element, display) {
    if (!element) {
      return;
    }

    // You can't use setDisplay with SVG on IE, because classList isn't on SVG
    // elements on that browser.  It's better to find out on Chrome through an
    // assertion, rather than wait for a failed test pass later on IE.
    goog.asserts.assert(!(element instanceof SVGElement),
        'Do not use setDisplay with SVG elements!');

    if (display) {
      element.classList.add('shaka-displayed');
      // Removing a non-existent class doesn't throw, so, even if
      // the element is not hidden, this should be fine. Same for displayed
      // below.
      element.classList.remove('shaka-hidden');
    } else {
      element.classList.add('shaka-hidden');
      element.classList.remove('shaka-displayed');
    }
  }
};