drupal/core/modules/edit/edit.module

<?php

/**
 * @file
 * Provides in-place content editing functionality for fields.
 *
 * The Edit module makes content editable in-place. Rather than having to visit
 * a separate page to edit content, it may be edited in-place.
 *
 * Technically, this module adds classes and data- attributes to fields and
 * entities, enabling them for in-place editing.
 */

use Drupal\Core\Entity\EntityInterface;
use Drupal\edit\Form\EditFieldForm;
use Drupal\Component\Utility\NestedArray;

/**
 * Implements hook_custom_theme().
 *
 * @todo Add an event subscriber to the Ajax system to automatically set the
 *   base page theme for all Ajax requests, and then remove this one off.
 */
function edit_custom_theme() {
  if (substr(current_path(), 0, 5) === 'edit/') {
    return ajax_base_page_theme();
  }
}

/**
 * Implements hook_permission().
 */
function edit_permission() {
  return array(
    'access in-place editing' => array(
      'title' => t('Access in-place editing'),
    ),
  );
}

/**
 * Implements hook_page_build().
 *
 * Adds the edit library to the page for any user who has the 'access in-place
 * editing' permission.
 */
function edit_page_build(&$page) {
  if (!user_access('access in-place editing')) {
    return;
  }

  $page['#attached']['js'][] = array(
    'type' => 'setting',
    'data' => array('edit' => array(
      'fieldFormURL' => url('edit/form/!entity_type/!id/!field_name/!langcode/!view_mode'),
      'context' => 'body',
    )),
  );
  $page['#attached']['library'][] = array('edit', 'edit');
}

/**
 * Implements hook_library_info().
 */
function edit_library_info() {
  $path = drupal_get_path('module', 'edit');
  $options = array(
    'scope' => 'footer',
  );
  $libraries['edit'] = array(
    'title' => 'Edit: in-place editing',
    'version' => VERSION,
    'js' => array(
      // Core.
      $path . '/js/edit.js' => $options,
      // Models.
      $path . '/js/models/AppModel.js' => $options,
      $path . '/js/models/EntityModel.js' => $options,
      $path . '/js/models/FieldModel.js' => $options,
      $path . '/js/models/EditorModel.js' => $options,
      // Views.
      $path . '/js/views/AppView.js' => $options,
      $path . '/js/views/EditorDecorationView.js' => $options,
      $path . '/js/views/ContextualLinkView.js' => $options,
      $path . '/js/views/ModalView.js' => $options,
      $path . '/js/views/FieldToolbarView.js' => $options,
      $path . '/js/views/EditorView.js' => $options,
      // Other.
      $path . '/js/util.js' => $options,
      $path . '/js/theme.js' => $options,
    ),
    'css' => array(
      $path . '/css/edit.css' => array(),
    ),
    'dependencies' => array(
      array('system', 'jquery'),
      array('system', 'underscore'),
      array('system', 'backbone'),
      array('system', 'jquery.form'),
      array('system', 'drupal.form'),
      array('system', 'drupal.ajax'),
      array('system', 'drupalSettings'),
    ),
  );
  $libraries['edit.editorWidget.form'] = array(
    'title' => 'Form in-place editor',
    'version' => VERSION,
    'js' => array(
      $path . '/js/editors/formEditor.js' => $options,
    ),
    'dependencies' => array(
      array('edit', 'edit'),
    ),
  );
  $libraries['edit.editorWidget.direct'] = array(
    'title' => 'Direct in-place editor',
    'version' => VERSION,
    'js' => array(
      $path . '/js/editors/directEditor.js' => $options,
    ),
    'dependencies' => array(
      array('edit', 'edit'),
    ),
  );

  return $libraries;
}

/**
 * Implements hook_preprocess_HOOK() for field.tpl.php.
 */
function edit_preprocess_field(&$variables) {
  $element = $variables['element'];
  $entity = $element['#object'];
  $variables['attributes']['data-edit-id'] = $entity->entityType() . '/' . $entity->id() . '/' . $element['#field_name'] . '/' . $element['#language'] . '/' . $element['#view_mode'];
}

/**
 * Implements hook_preprocess_HOOK() for node.html.twig.
 *
 * @todo Remove this, handle in generic way: http://drupal.org/node/1972514.
 */
function edit_preprocess_node(&$variables) {
  $node = $variables['elements']['#node'];
  $variables['attributes']['data-edit-entity'] = 'node/' . $node->nid;
}

/**
 * Implements hook_preprocess_HOOK() for taxonomy-term.tpl.php.
 *
 * @todo Remove this, handle in generic way: http://drupal.org/node/1972514.
 */
function edit_preprocess_taxonomy_term(&$variables) {
  $term = $variables['elements']['#term'];
  $variables['attributes']['data-edit-entity'] = 'taxonomy_term/' . $term->id();
}

/**
 * Implements hook_preprocess_HOOK() for block.html.twig.
 *
 * @todo Remove this, handle in generic way: http://drupal.org/node/1972514.
 */
function edit_preprocess_block(&$variables) {
  if (isset($variables['elements']['content']['#custom_block'])) {
    $custom_block = $variables['elements']['content']['#custom_block'];
    $variables['attributes']['data-edit-entity'] = 'custom_block/' . $custom_block->id();
  }
}

/**
 * Form constructor for the field editing form.
 *
 * @ingroup forms
 */
function edit_field_form(array $form, array &$form_state, EntityInterface $entity, $field_name) {
  $form_handler = new EditFieldForm();
  return $form_handler->build($form, $form_state, $entity, $field_name);
}