Linking to external resources from the Drupal appearance page

Linking to external resources from the Drupal appearance page.md

Adding links to Pattern Lab on Drupal Appearance page

Add this to THEME-NAME.info.yml:

resources:
  pattern-lab: /themes/custom/THEME_NAME/pattern-lab/public/
  sassdoc: /themes/custom/THEME_NAME/dest/sassdoc/

Add this code to a custom module:

<?php
/**
 * @file
 * Module code for Pattern Lab.
 */

use \Drupal\Core\Url;

/**
 * Implements hook_system_themes_page_alter().
 */
function MODULE_NAME_system_themes_page_alter($theme_groups)
{
  foreach ($theme_groups['installed'] as $theme) {
    if (isset($theme->info['resources']['pattern-lab'])) {
      $theme->operations[] = [
        'title' => t('Pattern Lab'),
        'url' => Url::fromUri('base:' . $theme->info['resources']['pattern-lab']),
        'attributes' => ['title' => t('Pattern Lab for @theme theme', ['@theme' => $theme->info['name']])],
      ];
    }
    if (isset($theme->info['resources']['sassdoc'])) {
      $theme->operations[] = [
        'title' => t('SassDoc'),
        'url' => Url::fromUri('base:' . $theme->info['resources']['sassdoc']),
        'attributes' => ['title' => t('SassDoc for @theme theme', ['@theme' => $theme->info['name']])],
      ];
    }
  }
}