CKEditorPluginCssInterface.php

<?php

namespace Drupal\ckeditor;

use Drupal\editor\Entity\Editor;

/**
 * Defines an interface for CKEditor plugins with associated CSS.
 *
 * This allows a CKEditor plugin to add additional CSS in iframe CKEditor
 * instances without needing to implement hook_ckeditor_css_alter().
 *
 * @see \Drupal\ckeditor\CKEditorPluginInterface
 * @see \Drupal\ckeditor\CKEditorPluginButtonsInterface
 * @see \Drupal\ckeditor\CKEditorPluginContextualInterface
 * @see \Drupal\ckeditor\CKEditorPluginConfigurableInterface
 * @see \Drupal\ckeditor\CKEditorPluginBase
 * @see \Drupal\ckeditor\CKEditorPluginManager
 * @see \Drupal\ckeditor\Annotation\CKEditorPlugin
 * @see plugin_api
 */
interface CKEditorPluginCssInterface extends CKEditorPluginInterface {
    
    /**
     * Retrieves enabled plugins' iframe instance CSS files.
     *
     * Note: this does not use a Drupal asset library because this CSS will be
     * loaded by CKEditor, not by Drupal.
     *
     * @param \Drupal\editor\Entity\Editor $editor
     *   A configured text editor object.
     *
     * @return string[]
     *   An array of CSS files. This is a flat list of file paths relative to
     *   the Drupal root.
     */
    public function getCssFiles(Editor $editor);

}