class WysiwygEditor

class WysiwygEditor extends InPlaceEditorBase {
  
  /**
   * {@inheritdoc}
   */
  public function isCompatible(FieldItemListInterface $items) {
    $field_definition = $items->getFieldDefinition();
    // This editor is incompatible with multivalued fields.
    if ($field_definition->getFieldStorageDefinition()
      ->getCardinality() != 1) {
      return FALSE;
    }
    // This editor is compatible with formatted ("rich") text fields; but only
    // if there is a currently active text format and that text format is the
    // 'full_html' text format.
    return $items[0]->format === 'full_html';
  }
  
  /**
   * {@inheritdoc}
   */
  public function getMetadata(FieldItemListInterface $items) {
    $metadata['format'] = $items[0]->format;
    return $metadata;
  }
  
  /**
   * {@inheritdoc}
   */
  public function getAttachments() {
    return [
      'library' => [
        'quickedit_test/not-existing-wysiwyg',
      ],
    ];
  }

}