layout.module

<?php

/**
 * @file
 * Manages page layouts for content presentation.
 */

/**
 * Implements hook_menu().
 */
function layout_menu() {
  $items['admin/structure/templates'] = array(
    'title' => 'Templates',
    'description' => 'Overview of the list of layout templates available.',
    'page callback' => 'layout_page_list',
    'access callback' => 'user_access',
    'access arguments' => array(
      'administer layouts',
    ),
    'file' => 'layout.admin.inc',
  );
  $items['admin/structure/templates/manage/%'] = array(
    'title' => 'View template',
    'page callback' => 'layout_page_view',
    'page arguments' => array(
      4,
    ),
    'access callback' => 'layout_user_access',
    'access arguments' => array(
      4,
    ),
    'file' => 'layout.admin.inc',
  );
  return $items;
}

/**
 * Access callback: Checks the existence of a layout.
 *
 * @param string $key
 *   The key of the page layout being requested.
 *
 * @return bool
 *   TRUE if the current user can access page layout menu items; FALSE
 *   otherwise.
 */
function layout_user_access($key) {
  return user_access('administer layouts') && layout_manager()
    ->getDefinition($key);
}

/**
 * Implements hook_permission().
 */
function layout_permission() {
  return array(
    'administer layouts' => array(
      'title' => t('Administer templates'),
      'description' => t('Access administration functions for templates.'),
    ),
  );
}

/**
 * Get the layout plugin manager instance.
 *
 * @return Drupal\layout\Plugin\Type\LayoutManager
 *   The layout plugin manager instance.
 */
function layout_manager() {
  return drupal_container()
    ->get('plugin.manager.layout');
}

/**
 * Implements hook_theme().
 *
 * Expose all layouts as theme items, so themes can override layout markup.
 */
function layout_theme($existing, $type, $theme, $path) {
  $items = array();
  foreach (layout_manager()
    ->getDefinitions() as $name => $layout) {
    $items[$layout['theme']] = array(
      'variables' => array(
        'content' => NULL,
      ),
      'path' => $layout['path'],
      'template' => $layout['template'],
    );
  }
  return $items;
}