ImageFormatterBase.php

<?php

namespace Drupal\image\Plugin\Field\FieldFormatter;

use Drupal\Core\Field\EntityReferenceFieldItemListInterface;
use Drupal\field\FieldConfigInterface;
use Drupal\file\Plugin\Field\FieldFormatter\FileFormatterBase;

/**
 * Base class for image file formatters.
 */
abstract class ImageFormatterBase extends FileFormatterBase {
    
    /**
     * {@inheritdoc}
     */
    protected function getEntitiesToView(EntityReferenceFieldItemListInterface $items, $langcode) {
        // Add the default image if needed.
        if ($items->isEmpty()) {
            $default_image = $this->getFieldSetting('default_image');
            // If we are dealing with a configurable field, look in both
            // instance-level and field-level settings.
            if (empty($default_image['uuid']) && $this->fieldDefinition instanceof FieldConfigInterface) {
                $default_image = $this->fieldDefinition
                    ->getFieldStorageDefinition()
                    ->getSetting('default_image');
            }
            if (!empty($default_image['uuid']) && ($file = \Drupal::service('entity.repository')->loadEntityByUuid('file', $default_image['uuid']))) {
                // Clone the FieldItemList into a runtime-only object for the formatter,
                // so that the fallback image can be rendered without affecting the
                // field values in the entity being rendered.
                $items = clone $items;
                $items->setValue([
                    'target_id' => $file->id(),
                    'alt' => $default_image['alt'],
                    'title' => $default_image['title'],
                    'width' => $default_image['width'],
                    'height' => $default_image['height'],
                    'entity' => $file,
                    '_loaded' => TRUE,
                    '_is_default' => TRUE,
                ]);
                $file->_referringItem = $items[0];
            }
        }
        return parent::getEntitiesToView($items, $langcode);
    }

}