class ImageUrlFormatter

class ImageUrlFormatter extends ImageFormatterBase {
  
  /**
   * The image style entity storage.
   *
   * @var \Drupal\image\ImageStyleStorageInterface
   */
  protected $imageStyleStorage;
  
  /**
   * The current user.
   *
   * @var \Drupal\Core\Session\AccountInterface
   */
  protected $currentUser;
  
  /**
   * Constructs an ImageFormatter object.
   *
   * @param string $plugin_id
   *   The plugin ID for the formatter.
   * @param mixed $plugin_definition
   *   The plugin implementation definition.
   * @param \Drupal\Core\Field\FieldDefinitionInterface $field_definition
   *   The definition of the field to which the formatter is associated.
   * @param array $settings
   *   The formatter settings.
   * @param string $label
   *   The formatter label display setting.
   * @param string $view_mode
   *   The view mode.
   * @param array $third_party_settings
   *   Any third party settings.
   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
   *   The entity type manager.
   * @param \Drupal\Core\Session\AccountInterface $current_user
   *   The current user.
   */
  public function __construct($plugin_id, $plugin_definition, FieldDefinitionInterface $field_definition, array $settings, $label, $view_mode, array $third_party_settings, EntityTypeManagerInterface $entity_type_manager, AccountInterface $current_user) {
    parent::__construct($plugin_id, $plugin_definition, $field_definition, $settings, $label, $view_mode, $third_party_settings);
    $this->imageStyleStorage = $entity_type_manager->getStorage('image_style');
    $this->currentUser = $current_user;
  }
  
  /**
   * {@inheritdoc}
   */
  public static function defaultSettings() {
    return [
      'image_style' => '',
    ];
  }
  
  /**
   * {@inheritdoc}
   */
  public function settingsForm(array $form, FormStateInterface $form_state) {
    $element = parent::settingsForm($form, $form_state);
    unset($element['image_link'], $element['image_loading']);
    $image_styles = image_style_options(FALSE);
    $description_link = Link::fromTextAndUrl($this->t('Configure Image Styles'), Url::fromRoute('entity.image_style.collection'));
    $element['image_style'] = [
      '#title' => $this->t('Image style'),
      '#type' => 'select',
      '#default_value' => $this->getSetting('image_style'),
      '#empty_option' => $this->t('None (original image)'),
      '#options' => $image_styles,
      '#description' => $description_link->toRenderable() + [
        '#access' => $this->currentUser
          ->hasPermission('administer image styles'),
      ],
    ];
    return $element;
  }
  
  /**
   * {@inheritdoc}
   */
  public function settingsSummary() {
    $summary = [];
    $image_styles = image_style_options(FALSE);
    // Unset possible 'No defined styles' option.
    unset($image_styles['']);
    // Styles could be lost because of enabled/disabled modules that defines
    // their styles in code.
    $image_style_setting = $this->getSetting('image_style');
    if (isset($image_styles[$image_style_setting])) {
      $summary[] = $this->t('Image style: @style', [
        '@style' => $image_styles[$image_style_setting],
      ]);
    }
    else {
      $summary[] = $this->t('Original image');
    }
    return array_merge($summary, parent::settingsSummary());
  }
  
  /**
   * {@inheritdoc}
   */
  public function viewElements(FieldItemListInterface $items, $langcode) {
    $elements = [];
    /** @var \Drupal\Core\Field\EntityReferenceFieldItemListInterface $items */
    if (empty($images = $this->getEntitiesToView($items, $langcode))) {
      // Early opt-out if the field is empty.
      return $elements;
    }
    /** @var \Drupal\image\ImageStyleInterface $image_style */
    $image_style = $this->imageStyleStorage
      ->load($this->getSetting('image_style'));
    /** @var \Drupal\Core\File\FileUrlGeneratorInterface $file_url_generator */
    $file_url_generator = \Drupal::service('file_url_generator');
    /** @var \Drupal\file\FileInterface[] $images */
    foreach ($images as $delta => $image) {
      $image_uri = $image->getFileUri();
      $url = $image_style ? $file_url_generator->transformRelative($image_style->buildUrl($image_uri)) : $file_url_generator->generateString($image_uri);
      // Add cacheability metadata from the image and image style.
      $cacheability = CacheableMetadata::createFromObject($image);
      if ($image_style) {
        $cacheability->addCacheableDependency(CacheableMetadata::createFromObject($image_style));
      }
      $elements[$delta] = [
        '#markup' => $url,
      ];
      $cacheability->applyTo($elements[$delta]);
    }
    return $elements;
  }

}