diff core/modules/block/src/Plugin/DisplayVariant/BlockPageVariant.php @ 0:4c8ae668cc8c

Initial import (non-working)

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/core/modules/block/src/Plugin/DisplayVariant/BlockPageVariant.php	Wed Nov 29 16:09:58 2017 +0000
@@ -0,0 +1,203 @@
+<?php
+
+namespace Drupal\block\Plugin\DisplayVariant;
+
+use Drupal\block\BlockRepositoryInterface;
+use Drupal\Core\Block\MainContentBlockPluginInterface;
+use Drupal\Core\Block\TitleBlockPluginInterface;
+use Drupal\Core\Block\MessagesBlockPluginInterface;
+use Drupal\Core\Cache\CacheableMetadata;
+use Drupal\Core\Display\PageVariantInterface;
+use Drupal\Core\Entity\EntityViewBuilderInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Core\Display\VariantBase;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Provides a page display variant that decorates the main content with blocks.
+ *
+ * To ensure essential information is displayed, each essential part of a page
+ * has a corresponding block plugin interface, so that BlockPageVariant can
+ * automatically provide a fallback in case no block for each of these
+ * interfaces is placed.
+ *
+ * @see \Drupal\Core\Block\MainContentBlockPluginInterface
+ * @see \Drupal\Core\Block\MessagesBlockPluginInterface
+ *
+ * @PageDisplayVariant(
+ *   id = "block_page",
+ *   admin_label = @Translation("Page with blocks")
+ * )
+ */
+class BlockPageVariant extends VariantBase implements PageVariantInterface, ContainerFactoryPluginInterface {
+
+  /**
+   * The block repository.
+   *
+   * @var \Drupal\block\BlockRepositoryInterface
+   */
+  protected $blockRepository;
+
+  /**
+   * The block view builder.
+   *
+   * @var \Drupal\Core\Entity\EntityViewBuilderInterface
+   */
+  protected $blockViewBuilder;
+
+  /**
+   * The Block entity type list cache tags.
+   *
+   * @var string[]
+   */
+  protected $blockListCacheTags;
+
+  /**
+   * The render array representing the main page content.
+   *
+   * @var array
+   */
+  protected $mainContent = [];
+
+  /**
+   * The page title: a string (plain title) or a render array (formatted title).
+   *
+   * @var string|array
+   */
+  protected $title = '';
+
+  /**
+   * Constructs a new BlockPageVariant.
+   *
+   * @param array $configuration
+   *   A configuration array containing information about the plugin instance.
+   * @param string $plugin_id
+   *   The plugin ID for the plugin instance.
+   * @param mixed $plugin_definition
+   *   The plugin implementation definition.
+   * @param \Drupal\block\BlockRepositoryInterface $block_repository
+   *   The block repository.
+   * @param \Drupal\Core\Entity\EntityViewBuilderInterface $block_view_builder
+   *   The block view builder.
+   * @param string[] $block_list_cache_tags
+   *   The Block entity type list cache tags.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, BlockRepositoryInterface $block_repository, EntityViewBuilderInterface $block_view_builder, array $block_list_cache_tags) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+    $this->blockRepository = $block_repository;
+    $this->blockViewBuilder = $block_view_builder;
+    $this->blockListCacheTags = $block_list_cache_tags;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $container->get('block.repository'),
+      $container->get('entity.manager')->getViewBuilder('block'),
+      $container->get('entity.manager')->getDefinition('block')->getListCacheTags()
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setMainContent(array $main_content) {
+    $this->mainContent = $main_content;
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setTitle($title) {
+    $this->title = $title;
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function build() {
+    // Track whether blocks showing the main content and messages are displayed.
+    $main_content_block_displayed = FALSE;
+    $messages_block_displayed = FALSE;
+
+    $build = [
+      '#cache' => [
+        'tags' => $this->blockListCacheTags,
+      ],
+    ];
+    // Load all region content assigned via blocks.
+    $cacheable_metadata_list = [];
+    foreach ($this->blockRepository->getVisibleBlocksPerRegion($cacheable_metadata_list) as $region => $blocks) {
+      /** @var $blocks \Drupal\block\BlockInterface[] */
+      foreach ($blocks as $key => $block) {
+        $block_plugin = $block->getPlugin();
+        if ($block_plugin instanceof MainContentBlockPluginInterface) {
+          $block_plugin->setMainContent($this->mainContent);
+          $main_content_block_displayed = TRUE;
+        }
+        elseif ($block_plugin instanceof TitleBlockPluginInterface) {
+          $block_plugin->setTitle($this->title);
+        }
+        elseif ($block_plugin instanceof MessagesBlockPluginInterface) {
+          $messages_block_displayed = TRUE;
+        }
+        $build[$region][$key] = $this->blockViewBuilder->view($block);
+
+        // The main content block cannot be cached: it is a placeholder for the
+        // render array returned by the controller. It should be rendered as-is,
+        // with other placed blocks "decorating" it. Analogous reasoning for the
+        // title block.
+        if ($block_plugin instanceof MainContentBlockPluginInterface || $block_plugin instanceof TitleBlockPluginInterface) {
+          unset($build[$region][$key]['#cache']['keys']);
+        }
+      }
+      if (!empty($build[$region])) {
+        // \Drupal\block\BlockRepositoryInterface::getVisibleBlocksPerRegion()
+        // returns the blocks in sorted order.
+        $build[$region]['#sorted'] = TRUE;
+      }
+    }
+
+    // If no block that shows the main content is displayed, still show the main
+    // content. Otherwise the end user will see all displayed blocks, but not
+    // the main content they came for.
+    if (!$main_content_block_displayed) {
+      $build['content']['system_main'] = $this->mainContent;
+    }
+
+    // If no block displays status messages, still render them.
+    if (!$messages_block_displayed) {
+      $build['content']['messages'] = [
+        '#weight' => -1000,
+        '#type' => 'status_messages',
+      ];
+    }
+
+    // If any render arrays are manually placed, render arrays and blocks must
+    // be sorted.
+    if (!$main_content_block_displayed || !$messages_block_displayed) {
+      unset($build['content']['#sorted']);
+    }
+
+    // The access results' cacheability is currently added to the top level of the
+    // render array. This is done to prevent issues with empty regions being
+    // displayed.
+    // This would need to be changed to allow caching of block regions, as each
+    // region must then have the relevant cacheable metadata.
+    $merged_cacheable_metadata = CacheableMetadata::createFromRenderArray($build);
+    foreach ($cacheable_metadata_list as $cacheable_metadata) {
+      $merged_cacheable_metadata = $merged_cacheable_metadata->merge($cacheable_metadata);
+    }
+    $merged_cacheable_metadata->applyTo($build);
+
+    return $build;
+  }
+
+}