Lb styles extending

11.4. Extending Layout Builder Styles

When to Use

When you need to programmatically alter which styles are available, modify CSS classes before rendering, or integrate custom logic into the style selection process.

Decision

If you need...	Use...	Why
Alter styles before rendering	Event subscriber on `SECTION_COMPONENT_BUILD_RENDER_ARRAY`	Modify `$build['#attributes']['class']` array
Restrict styles by user role	Custom event subscriber checking permissions	Check `\Drupal::currentUser()->hasPermission()` before adding style
Add context-aware classes	Event subscriber checking node type or view mode	`$event->getComponent()->getEntity()` for context
Custom template suggestions	`hook_theme_suggestions_block_alter()`	Use `$variables['elements']['#layout_builder_style']`
Load styles programmatically	`\Drupal::entityTypeManager()->getStorage('layout_builder_style')->load($id)`	Access style config entities

Pattern

Custom Event Subscriber (After LB Styles):

// modules/custom/my_module/src/EventSubscriber/CustomStyleSubscriber.php
namespace Drupal\my_module\EventSubscriber;

use Drupal\layout_builder\Event\SectionComponentBuildRenderArrayEvent;
use Drupal\layout_builder\LayoutBuilderEvents;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;

class CustomStyleSubscriber implements EventSubscriberInterface {

  public static function getSubscribedEvents(): array {
    // Run AFTER layout_builder_styles (priority 50)
    $events[LayoutBuilderEvents::SECTION_COMPONENT_BUILD_RENDER_ARRAY] = [
      'onBuildRender',
      40,  // Lower priority = runs after LB Styles
    ];
    return $events;
  }

  public function onBuildRender(SectionComponentBuildRenderArrayEvent $event) {
    $build = $event->getBuild();

    // Access applied styles
    $selectedStyles = $event->getComponent()->get('layout_builder_styles_style');
    if (!$selectedStyles) {
      return;
    }

    // Add context-aware classes
    $node = \Drupal::routeMatch()->getParameter('node');
    if ($node && $node->bundle() === 'article') {
      $build['#attributes']['class'][] = 'article-component';
    }

    // Conditional class addition
    if (in_array('bg_primary', $selectedStyles)) {
      $build['#attributes']['class'][] = 'has-colored-background';
    }

    $event->setBuild($build);
  }
}

Register Event Subscriber:

# modules/custom/my_module/my_module.services.yml
services:
  my_module.custom_style_subscriber:
    class: Drupal\my_module\EventSubscriber\CustomStyleSubscriber
    tags:
      - { name: event_subscriber }

Load and Inspect Style Entities:

// Load a specific style
$style = \Drupal::entityTypeManager()
  ->getStorage('layout_builder_style')
  ->load('padding_large');

if ($style) {
  $classes = $style->getClasses();        // "p-5"
  $type = $style->getType();              // "component" or "section"
  $group = $style->getGroup();            // "spacing"
  $restrictions = $style->getBlockRestrictions();  // Array of block plugin IDs
}

// Load all styles of a type
$query = \Drupal::entityTypeManager()
  ->getStorage('layout_builder_style')
  ->getQuery()
  ->accessCheck(FALSE)
  ->condition('type', 'section')
  ->sort('weight', 'ASC');
$ids = $query->execute();
$section_styles = \Drupal::entityTypeManager()
  ->getStorage('layout_builder_style')
  ->loadMultiple($ids);

Custom Template Suggestions Based on Styles:

// modules/custom/my_module/my_module.module
use Drupal\Core\Template\Attribute;

/**
 * Implements hook_theme_suggestions_block_alter().
 */
function my_module_theme_suggestions_block_alter(array &$suggestions, array $variables) {
  // LB Styles provides single-style template suggestions
  // Add custom logic for multiple styles
  $styles = $variables['elements']['#layout_builder_style'] ?? [];

  if (!empty($styles) && is_array($styles)) {
    // Add suggestion for combination of styles
    $style_combo = implode('_', $styles);
    $suggestions[] = 'block__lb_styles__' . $style_combo;

    // Add suggestion per individual style
    foreach ($styles as $style_id) {
      $suggestions[] = 'block__lb_style__' . $style_id;
    }
  }
}

Programmatically Apply Styles to Layouts:

// Apply style to section programmatically
$section = $layout_builder_section->getComponent($uuid);
$layout_settings = $section->getLayoutSettings();
$layout_settings['layout_builder_styles_style'] = ['padding_large', 'bg_primary'];
$section->setLayoutSettings($layout_settings);

// Apply style to component programmatically
$component = $section->getComponent($component_uuid);
$component->set('layout_builder_styles_style', ['shadow', 'rounded']);

Form Alter to Restrict Styles by Role:

// modules/custom/my_module/my_module.module

/**
 * Implements hook_form_alter().
 */
function my_module_form_alter(&$form, FormStateInterface $form_state, $form_id) {
  if ($form_id === 'layout_builder_add_block' || $form_id === 'layout_builder_update_block') {
    $current_user = \Drupal::currentUser();

    // Remove advanced styles for non-admin users
    if (!$current_user->hasPermission('administer layout builder styles')) {
      if (isset($form['layout_builder_style_effects'])) {
        foreach ($form['layout_builder_style_effects']['#options'] as $key => $label) {
          if (strpos($key, 'advanced_') === 0) {
            unset($form['layout_builder_style_effects']['#options'][$key]);
          }
        }
      }
    }
  }
}

Reference: modules/contrib/layout_builder_styles/src/EventSubscriber/BlockComponentRenderArraySubscriber.php

Common Mistakes

Wrong event priority → LB Styles uses priority 50. Use lower number (40) to run after, higher (60) to run before
Not checking if styles exist → Always check $selectedStyles is not empty before processing
Modifying config entities directly → Don't alter LayoutBuilderStyle entities at runtime. Alter render arrays instead
Not handling arrays → layout_builder_styles_style can be string or array. Always convert to array for processing
Forgetting cache tags → If loading style entities, add cache tags: $build['#cache']['tags'][] = 'config:layout_builder_styles.style.' . $style_id;
Breaking existing classes → When altering $build['#attributes']['class'], append don't replace: array_merge() not assignment
Not testing without LB Styles → Your code should gracefully degrade if module disabled