ISTWCMS-4027 Adding UW Service, and using it on Blog teaser.

src/Service/UWService.php

+<?php
+
+namespace Drupal\uw_cfg_common\Service;
+
+use Drupal\Core\Entity\EntityInterface;
+
+/**
+ * Class UWService
+ *
+ * @package Drupal\uw_cfg_common\Service
+ */
+class UWService implements UWServiceInterface {
+
+  /**
+   * {@inheritDoc}
+   */
+  public function prepareResponsiveImage(EntityInterface $entity, string $image_style): array {
+    // Load in the file object if we have one.
+    if ($file = $entity->field_media_image->entity) {
+      // Need to set these variables so that responsive image function,
+      // has all the necessary info to process the image style.
+      $variables['uri'] = $file->getFileUri();
+      $variables['responsive_image_style_id'] = $image_style;
+
+      // These is a function from the responsive image module that sets all
+      // the variables for the sources of the responsive image.
+      template_preprocess_responsive_image($variables);
+
+      // Step through each of the sources and setup our own sources array.
+      foreach ($variables['sources'] as $source) {
+        $variables['responsive_sources'][] = [
+          'srcset' => $source->storage()['srcset']->value(),
+          'media' => $source->storage()['media']->value(),
+          'type' => $source->storage()['type']->value(),
+        ];
+      }
+
+      return $variables;
+    }
+
+    return [];
+  }
+
+}

src/Service/UWServiceInterface.php

+<?php
+
+namespace Drupal\uw_cfg_common\Service;
+
+use Drupal\Core\Entity\EntityInterface;
+
+interface UWServiceInterface {
+
+  /**
+   * Prepares responsive image.
+   *
+   * @param \Drupal\Core\Entity\EntityInterface $entity
+   *   Image entity.
+   * @param string $image_style
+   *   Image style to be used for responsive image.
+   *
+   * @return array
+   *    Array with details for responsive image.
+   */
+  public function prepareResponsiveImage(EntityInterface $entity, string $image_style): array;
+}

uw_cfg_common.services.yml

+services:
+  uw_cfg_common.uw_service:
+    class: Drupal\uw_cfg_common\Service\UWService
+    arguments: []