class ImageUrlFormatter

class ImageUrlFormatter extends ImageFormatter {
    
    /**
     * {@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']);
        return $element;
    }
    
    /**
     * {@inheritdoc}
     */
    public function settingsSummary() {
        $summary = parent::settingsSummary();
        return [
            $summary[0],
        ];
    }
    
    /**
     * {@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\file\FileInterface[] $images */
        foreach ($images as $delta => $image) {
            $image_uri = $image->getFileUri();
            $url = $image_style ? $image_style->buildUrl($image_uri) : file_create_url($image_uri);
            $url = file_url_transform_relative($url);
            // 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;
    }

}