Issue #3494558: Copy image style effects optional when editing an image style effect.

Closes #3494558

responsive_image_style_builder.module

@@ -155,3 +155,74 @@ function responsive_image_style_builder_form_image_style_add_parent_effect_submi
     $derivativeStyle->save();
   }
 }
+
+/**
+ * Implements hook_form_FORM_ID_alter().
+ */
+function responsive_image_style_builder_form_image_effect_form_alter(&$form, FormStateInterface $form_state) {
+  // Get current image style from route
+  $current_style = \Drupal::routeMatch()->getParameter('image_style')->id();
+  
+  if (!str_ends_with($current_style, '_default')) {
+    return;
+  }
+
+  $form['copy_to_children'] = [
+    '#type' => 'checkbox',
+    '#title' => t('Copy to derivative image styles'),
+    '#description' => t('Apply these effect settings to all derivative image styles.'),
+    '#default_value' => FALSE,
+    '#weight' => 99,
+  ];
+  $form['#submit'][] = 'responsive_image_style_builder_effect_form_submit';
+}
+/**
+ * Custom submit handler for the image effect form.
+ */
+function responsive_image_style_builder_effect_form_submit(array $form, FormStateInterface $form_state) {
+  if (!$form_state->getValue('copy_to_children')) {
+    return;
+  }
+
+  // Get the current effect data
+  $effect_data = $form_state->getValue('data');
+  $effect_id = $form_state->getValue('id');
+  $effect_weight = $form_state->getValue('weight');
+
+  // Get current image style and its derivatives
+  $current_style = \Drupal::routeMatch()->getParameter('image_style');
+  $derivative_styles = \Drupal::service('risb.builder')->getDerivativeImageStyles($current_style->id());
+  
+  $updated_styles = 0;
+  foreach ($derivative_styles as $derivative_style) {
+    // Find if effect already exists in derivative
+    $existing_effect = NULL;
+    foreach ($derivative_style->getEffects() as $existing) {
+      if ($existing->getConfiguration()['id'] === $effect_id) {
+        $existing_effect = $existing;
+        break;
+      }
+    }
+
+    if ($existing_effect) {
+      // Update only if effect exists
+      $configuration = $existing_effect->getConfiguration();
+      $configuration['data'] = $effect_data;
+      $configuration['weight'] = $effect_weight;
+      
+      $derivative_style->deleteImageEffect($existing_effect);
+      $derivative_style->addImageEffect($configuration);
+      $derivative_style->save();
+      $updated_styles++;
+    }
+  }
+
+  if ($updated_styles > 0) {
+    \Drupal::messenger()->addMessage(t('Effect configuration has been updated in @count derivative image styles.', [
+      '@count' => $updated_styles
+    ]));
+  } else {
+    \Drupal::messenger()->addWarning(t('No derivative styles found with this effect to update.'));
+  }
+}
+