datafield-1.x-dev/src/Plugin/DataFieldFormatterInterface.php

<?php

namespace Drupal\datafield\Plugin;

use Drupal\Core\Field\FieldItemListInterface;
use Drupal\Core\Form\FormStateInterface;

/**
 * Interface definition for field widget plugins.
 *
 * This interface details the methods that most plugin implementations will want
 * to override. See Drupal\Core\Field\WidgetBaseInterface for base
 * wrapping methods that should most likely be inherited directly from
 * Drupal\Core\Field\WidgetBase.
 *
 * @ingroup field_widget
 */
interface DataFieldFormatterInterface {

  /**
   * Returns a form to configure settings for the widget.
   *
   * Invoked from \Drupal\field_ui\Form\EntityDisplayFormBase to allow
   * administrators to configure the widget. The field_ui module takes care of
   * handling submitted form values.
   *
   * @param array $form
   *   The form where the settings form is being included in.
   * @param \Drupal\Core\Form\FormStateInterface $form_state
   *   The current state of the form.
   *
   * @return array
   *   The form definition for the widget settings.
   */
  public function settingsForm(array $form, FormStateInterface $form_state);

  /**
   * Returns a short summary for the current widget settings.
   *
   * If an empty result is returned, a UI can still be provided to display
   * a settings form in case the widget has configurable settings.
   *
   * @return array
   *   A short summary of the widget settings.
   */
  public function settingsSummary();

  /**
   * Builds a renderable array for a field value.
   *
   * @param \Drupal\Core\Field\FieldItemListInterface $items
   *   The field values to be rendered.
   * @param string $langcode
   *   The language that should be used to render the field.
   *
   * @return array
   *   A renderable array for $items, as an array of child elements keyed by
   *   consecutive numeric indexes starting from 0.
   */
  public function viewElements(FieldItemListInterface $items, $langcode);

}