Add image-style config

Closes #3468348

src/Plugin/CustomElementsFieldFormatter/FileCeFieldFormatter.php

@@ -3,6 +3,8 @@
 namespace Drupal\custom_elements\Plugin\CustomElementsFieldFormatter;
 
 use Drupal\Core\Field\FieldItemInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\custom_elements\CustomElementsImageStyleConfigTrait;
 
 /**
  * Implementation of the 'file' custom element formatter plugin.
@@ -25,13 +27,58 @@ use Drupal\Core\Field\FieldItemInterface;
  */
 class FileCeFieldFormatter extends FlattenedCeFieldFormatter {
 
+  use CustomElementsImageStyleConfigTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function defaultSettings() {
+    return [
+      'image_style' => '',
+    ] + parent::defaultSettings();
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
+    $element = parent::buildConfigurationForm($form, $form_state);
+    if ($this->getFieldDefinition()->getType() === 'image') {
+      $element += $this->getImageStyleConfigForm($this->configuration['image_style'] ?? '');
+    }
+    return $element;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitConfigurationForm(array &$form, FormStateInterface $form_state) {
+    if ($this->getFieldDefinition()->getType() === 'image') {
+      $this->configuration['image_style'] = $form_state->getValue('image_style');
+    }
+  }
+
   /**
    * {@inheritdoc}
    */
   protected function getFieldItemProperties(FieldItemInterface $field_item, array $ignore_properties = []): array {
     $values = parent::getFieldItemProperties($field_item, ['target_id']);
-    // Add url property of the referenced file to the values.
-    $values['url'] = $field_item->entity->uri->url;
+    if ($this->getFieldDefinition()->getType() === 'image' && !empty($this->configuration['image_style'])) {
+      $image_style = $this->loadImageStyle($this->configuration['image_style']);
+      if ($image_style) {
+        $values['url'] = $this->getImageStyleUrl($image_style, $field_item->entity->getFileUri());
+      }
+      else {
+        // Wrong/incomplete backend configuration must be fixed, rather than
+        // silently output an unintended response.
+        throw new \UnexpectedValueException("Image style '{$this->configuration['image_style']}' cannot be loaded.");
+      }
+    }
+    else {
+      // Add url property of the referenced file to the values.
+      $values['url'] = $field_item->entity->uri->url;
+    }
+
     return $values;
   }
 
@@ -40,6 +87,9 @@ class FileCeFieldFormatter extends FlattenedCeFieldFormatter {
    */
   public function settingsSummary() {
     $summary = parent::settingsSummary();
+    if ($this->getFieldDefinition()->getType() === 'image') {
+      $summary += $this->getSettingsSummary($this->configuration['image_style'] ?? '');
+    }
     // target_id is the 'main' property, so nothing gets set into a slot.
     $summary[] = $this->t('Is Slot is ignored.');
     return $summary;