Issue #3013187 by tim.plunkett: Rename PlaceholderInterface to PreviewFallbackInterface

core/lib/Drupal/Core/Block/BlockBase.php

@@ -11,7 +11,7 @@
 use Drupal\Core\Language\LanguageInterface;
 use Drupal\Core\Plugin\PluginWithFormsInterface;
 use Drupal\Core\Plugin\PluginWithFormsTrait;
-use Drupal\Core\Render\PlaceholderInterface;
+use Drupal\Core\Render\PreviewFallbackInterface;
 use Drupal\Core\Session\AccountInterface;
 use Drupal\Component\Transliteration\TransliterationInterface;
 
@@ -24,7 +24,7 @@
  *
  * @ingroup block_api
  */
-abstract class BlockBase extends ContextAwarePluginBase implements BlockPluginInterface, PluginWithFormsInterface, PlaceholderInterface {
+abstract class BlockBase extends ContextAwarePluginBase implements BlockPluginInterface, PluginWithFormsInterface, PreviewFallbackInterface {
 
   use ContextAwarePluginAssignmentTrait;
   use MessengerTrait;
@@ -256,7 +256,7 @@ public function getMachineNameSuggestion() {
   /**
    * {@inheritdoc}
    */
-  public function getPlaceholderString() {
+  public function getPreviewFallbackString() {
     return $this->t('Placeholder for the "@block" block', ['@block' => $this->label()]);
   }
 

core/lib/Drupal/Core/Render/PlaceholderInterface.php → core/lib/Drupal/Core/Render/PreviewFallbackInterface.php

@@ -3,19 +3,19 @@
 namespace Drupal\Core\Render;
 
 /**
- * Allows an element to provide a placeholder representation of itself.
+ * Allows an element to provide a fallback representation of itself for preview.
  */
-interface PlaceholderInterface {
+interface PreviewFallbackInterface {
 
   /**
-   * Returns a string to be used as a placeholder.
+   * Returns a string to be used as a fallback during preview.
    *
    * This is typically used when an element has no output and must be displayed,
    * for example during configuration.
    *
    * @return string|\Drupal\Core\StringTranslation\TranslatableMarkup
-   *   A placeholder string for this element.
+   *   A string representing for this.
    */
-  public function getPlaceholderString();
+  public function getPreviewFallbackString();
 
 }

core/modules/layout_builder/src/EventSubscriber/BlockComponentRenderArray.php

@@ -6,7 +6,7 @@
 use Drupal\Core\Access\AccessResult;
 use Drupal\Core\Block\BlockPluginInterface;
 use Drupal\Core\Render\Element;
-use Drupal\Core\Render\PlaceholderInterface;
+use Drupal\Core\Render\PreviewFallbackInterface;
 use Drupal\Core\Session\AccountInterface;
 use Drupal\layout_builder\Access\LayoutPreviewAccessAllowed;
 use Drupal\layout_builder\Event\SectionComponentBuildRenderArrayEvent;
@@ -100,8 +100,8 @@ public function onBuildRender(SectionComponentBuildRenderArrayEvent $event) {
         '#weight' => $event->getComponent()->getWeight(),
         'content' => $block->build(),
       ];
-      if ($event->inPreview() && Element::isEmpty($build['content']) && $block instanceof PlaceholderInterface) {
-        $build['content']['#markup'] = $block->getPlaceholderString();
+      if ($event->inPreview() && Element::isEmpty($build['content']) && $block instanceof PreviewFallbackInterface) {
+        $build['content']['#markup'] = $block->getPreviewFallbackString();
       }
       $event->setBuild($build);
     }

core/modules/layout_builder/src/Plugin/Block/ExtraFieldBlock.php

@@ -130,7 +130,7 @@ public function build() {
         // render array. If the hook is invoked the placeholder will be
         // replaced.
         // @see ::replaceFieldPlaceholder()
-        '#markup' => $this->getPlaceholderString(),
+        '#markup' => $this->getPreviewFallbackString(),
       ];
     }
     CacheableMetadata::createFromObject($this)->applyTo($build);
@@ -140,7 +140,7 @@ public function build() {
   /**
    * {@inheritdoc}
    */
-  public function getPlaceholderString() {
+  public function getPreviewFallbackString() {
     $entity = $this->getEntity();
     $extra_fields = $this->entityFieldManager->getExtraFields($entity->getEntityTypeId(), $entity->bundle());
     return new TranslatableMarkup('Placeholder for the "@field" field', ['@field' => $extra_fields['display'][$this->fieldName]['label']]);

core/modules/layout_builder/src/Plugin/Block/FieldBlock.php

@@ -166,7 +166,7 @@ public function build() {
   /**
    * {@inheritdoc}
    */
-  public function getPlaceholderString() {
+  public function getPreviewFallbackString() {
     return new TranslatableMarkup('Placeholder for the "@field" field', ['@field' => $this->getFieldDefinition()->getLabel()]);
   }
 

core/modules/views/src/Plugin/Block/ViewsBlockBase.php

@@ -108,7 +108,7 @@ public function defaultConfiguration() {
   /**
    * {@inheritdoc}
    */
-  public function getPlaceholderString() {
+  public function getPreviewFallbackString() {
     return $this->t('Placeholder for the "@view" views block', ['@view' => $this->view->storage->label()]);
   }