[RW-816] Fix: ensure webp derivative images are deleted

html/modules/custom/reliefweb_utility/reliefweb_utility.module

@@ -89,3 +89,23 @@ function reliefweb_utility_file_presave(FileInterface $file) {
     }
   }
 }
+
+/**
+ * Implements hook_entity_type_alter().
+ *
+ * Replace the image style class so we can properly delete webp versions of the
+ * derivative images because this is not done by image_optimize_webp, notably
+ * because there is no hook provided for that by the image module.
+ *
+ * Normally this runs after the imageapi_optimize_entity_type_alter() due to
+ * the alphabetical order.
+ */
+function reliefweb_utility_entity_type_alter(array &$entity_types) {
+  /** @var \Drupal\Core\Entity\EntityTypeInterface[] $entity_types */
+  if (isset($entity_types['image_style'])) {
+    $image_style = $entity_types['image_style'];
+    if ($image_style->getClass() === 'Drupal\imageapi_optimize\Entity\ImageStyleWithPipeline') {
+      $image_style->setClass('Drupal\reliefweb_utility\Entity\ImageStyleWithPipeline');
+    }
+  }
+}

html/modules/custom/reliefweb_utility/src/Entity/ImageStyleWithPipeline.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace Drupal\reliefweb_utility\Entity;
+
+use Drupal\Core\File\Exception\FileException;
+use Drupal\imageapi_optimize\Entity\ImageStyleWithPipeline as BaseImageStyleWithPipeline;
+
+/**
+ * Override of the ImageStyleWithPipeline to also delete webp images.
+ */
+class ImageStyleWithPipeline extends BaseImageStyleWithPipeline {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function flush($path = NULL) {
+    $result = parent::flush($path);
+
+    // Also delete the webp version of the image if it exists.
+    if (isset($path)) {
+      /** @var \Drupal\Core\File\FileSystemInterface $file_system */
+      $file_system = \Drupal::service('file_system');
+      $derivative_uri = $this->buildUri($path);
+      $derivative_uri_webp = $derivative_uri . '.webp';
+
+      if (file_exists($derivative_uri_webp)) {
+        try {
+          $file_system->delete($derivative_uri_webp);
+        }
+        catch (FileException $exception) {
+          // Ignore failed deletion.
+        }
+      }
+    }
+
+    return $result;
+  }
+
+}