[Summary view] [Print] [Text view]

   1  <?php
   2  /**
   3   * Server-side rendering of the `core/details` block.
   4   *
   5   * @package WordPress
   6   */
   7  
   8  /**
   9   * Sets fetchpriority="low" on all IMG tags within the collapsed Details block.
  10   *
  11   * Images in a collapsed Details block are hidden until the block is expanded, so they should
  12   * not compete with any resources in the critical rendering path, such as the LCP element image.
  13   *
  14   * @since 7.0.0
  15   *
  16   * @param string $block_content The block content.
  17   * @param array  $block         The full block, including name and attributes.
  18   * @return string Modified HTML with fetchpriority="low" on all IMG tags when the showContent attribute is false.
  19   */
  20  function block_core_details_set_img_fetchpriority_low( $block_content, array $block ): string {
  21      if ( ! is_string( $block_content ) ) {
  22          return '';
  23      }
  24  
  25      // If the Details block is open by default, short-circuit to let core add fetchpriority=high if appropriate.
  26      if ( $block['attrs']['showContent'] ?? false ) {
  27          return $block_content;
  28      }
  29  
  30      $tags = new WP_HTML_Tag_Processor( $block_content );
  31      while ( $tags->next_tag( 'IMG' ) ) {
  32          $tags->set_attribute( 'fetchpriority', 'low' );
  33      }
  34      return $tags->get_updated_html();
  35  }
  36  
  37  add_filter( 'render_block_core/details', 'block_core_details_set_img_fetchpriority_low', 10, 2 );
  38  
  39  /**
  40   * Registers the `core/details` block on server.
  41   *
  42   * @since 7.0.0
  43   */
  44  function register_block_core_details() {
  45      register_block_type_from_metadata( __DIR__ . '/details' );
  46  }
  47  add_action( 'init', 'register_block_core_details' );