wordpress/wp-includes/blocks/cover.php

<?php
/**
 * Server-side rendering of the `core/cover` block.
 *
 * @package WordPress
 */

/**
 * Renders the `core/cover` block on server.
 *
 * @since 6.0.0
 *
 * @param array  $attributes The block attributes.
 * @param string $content    The block rendered content.
 *
 * @return string Returns the cover block markup, if useFeaturedImage is true.
 */
function render_block_core_cover( $attributes, $content ) {
	// Handle embed video background.
	if (
		isset( $attributes['backgroundType'] ) &&
		'embed-video' === $attributes['backgroundType'] &&
		isset( $attributes['url'] ) &&
		! empty( $attributes['url'] ) &&
		is_string( $attributes['url'] )
	) {
		$url = $attributes['url'];

		// Use WordPress's native oEmbed processing (includes caching).
		$oembed_html = wp_oembed_get( $url );

		if ( $oembed_html ) {
			// Extract iframe src from the oEmbed HTML.
			preg_match( '/src=["\']([^"\']+)["\']/', $oembed_html, $src_matches );
			if ( ! empty( $src_matches[1] ) ) {
				$iframe_src = $src_matches[1];

				// Detect provider from iframe src URL.
				$lower_src = strtolower( $iframe_src );
				$provider  = null;

				if ( strpos( $lower_src, 'youtube.com' ) !== false || strpos( $lower_src, 'youtu.be' ) !== false ) {
					$provider = 'youtube';
				} elseif ( strpos( $lower_src, 'vimeo.com' ) !== false ) {
					$provider = 'vimeo';
				} elseif ( strpos( $lower_src, 'videopress.com' ) !== false ) {
					$provider = 'videopress';
				} elseif ( strpos( $lower_src, 'wordpress.tv' ) !== false ) {
					$provider = 'wordpress-tv';
				}

				// Modify iframe src to add background video parameters based on provider.
				$parsed_url = wp_parse_url( $iframe_src );
				if ( $parsed_url && isset( $parsed_url['host'] ) ) {
					// Parse existing query parameters.
					$query_params = array();
					if ( isset( $parsed_url['query'] ) ) {
						parse_str( $parsed_url['query'], $query_params );
					}

					// Add background video parameters based on provider.
					if ( 'youtube' === $provider ) {
						$query_params['autoplay']       = '1';
						$query_params['mute']           = '1';
						$query_params['loop']           = '1';
						$query_params['controls']       = '0';
						$query_params['modestbranding'] = '1';
						$query_params['playsinline']    = '1';
					} elseif ( 'vimeo' === $provider ) {
						$query_params['autoplay']    = '1';
						$query_params['muted']       = '1';
						$query_params['loop']        = '1';
						$query_params['background']  = '1';
						$query_params['controls']    = '0';
						$query_params['transparent'] = '0';
					} elseif ( 'videopress' === $provider || 'wordpress-tv' === $provider ) {
						$query_params['autoplay'] = '1';
						$query_params['loop']     = '1';
						$query_params['muted']    = '1';
					}

					// Rebuild the URL with new parameters.
					$iframe_src = $parsed_url['scheme'] . '://' . $parsed_url['host'];
					if ( isset( $parsed_url['path'] ) ) {
						$iframe_src .= $parsed_url['path'];
					}
					if ( ! empty( $query_params ) ) {
						$iframe_src .= '?' . http_build_query( $query_params );
					}
				}

				// Build the iframe HTML that will replace the figure.
				$iframe_html = sprintf(
					'<div class="wp-block-cover__video-background wp-block-cover__embed-background"><iframe src="%s" title="Background video" frameborder="0" allow="autoplay; fullscreen"></iframe></div>',
					esc_url( $iframe_src )
				);

				// Use the HTML API to find and replace the figure.wp-block-embed element.
				$processor = new WP_HTML_Tag_Processor( $content );

				if ( $processor->next_tag(
					array(
						'tag_name'   => 'FIGURE',
						'class_name' => 'wp-block-embed',
					)
				) ) {
					// Use regex with PREG_OFFSET_CAPTURE to find the position of the figure element.
					// This follows the same pattern used for featured image insertion below.
					$figure_pattern = '/<figure\s+[^>]*\bwp-block-embed\b[^>]*>.*?<\/figure>/is';
					if ( 1 === preg_match( $figure_pattern, $content, $matches, PREG_OFFSET_CAPTURE ) ) {
						$figure_start  = $matches[0][1];
						$figure_length = strlen( $matches[0][0] );
						$figure_end    = $figure_start + $figure_length;

						// Replace the figure element with the iframe HTML.
						$content = substr( $content, 0, $figure_start ) . $iframe_html . substr( $content, $figure_end );
					}
				}
			}
		}

		return $content;
	}

	if ( 'image' !== $attributes['backgroundType'] || false === $attributes['useFeaturedImage'] ) {
		return $content;
	}

	$object_position = isset( $attributes['focalPoint'] )
		? round( $attributes['focalPoint']['x'] * 100 ) . '% ' . round( $attributes['focalPoint']['y'] * 100 ) . '%'
		: null;

	if ( ! ( $attributes['hasParallax'] || $attributes['isRepeated'] ) ) {
		$attr = array(
			'class'           => 'wp-block-cover__image-background',
			'data-object-fit' => 'cover',
		);

		if ( $object_position ) {
			$attr['data-object-position'] = $object_position;
			$attr['style']                = 'object-position:' . $object_position . ';';
		}

		$image = get_the_post_thumbnail( null, $attributes['sizeSlug'] ?? 'post-thumbnail', $attr );
	} else {
		if ( in_the_loop() ) {
			update_post_thumbnail_cache();
		}
		$current_featured_image = get_the_post_thumbnail_url( null, $attributes['sizeSlug'] ?? null );
		if ( ! $current_featured_image ) {
			return $content;
		}

		$current_thumbnail_id = get_post_thumbnail_id();

		$processor = new WP_HTML_Tag_Processor( '<div></div>' );
		$processor->next_tag();

		$current_alt = trim( strip_tags( get_post_meta( $current_thumbnail_id, '_wp_attachment_image_alt', true ) ) );
		if ( $current_alt ) {
			$processor->set_attribute( 'role', 'img' );
			$processor->set_attribute( 'aria-label', $current_alt );
		}

		$processor->add_class( 'wp-block-cover__image-background' );
		$processor->add_class( 'wp-image-' . $current_thumbnail_id );
		if ( $attributes['hasParallax'] ) {
			$processor->add_class( 'has-parallax' );
		}
		if ( $attributes['isRepeated'] ) {
			$processor->add_class( 'is-repeated' );
		}

		$styles  = 'background-position:' . ( $object_position ?? '50% 50%' ) . ';';
		$styles .= 'background-image:url(' . esc_url( $current_featured_image ) . ');';
		$processor->set_attribute( 'style', $styles );

		$image = $processor->get_updated_html();
	}

	/*
	 * Inserts the featured image between the (1st) cover 'background' `span` and 'inner_container' `div`,
	 * and removes eventual whitespace characters between the two (typically introduced at template level)
	 */
	$inner_container_start = '/<div\b[^>]+wp-block-cover__inner-container[\s|"][^>]*>/U';
	if ( 1 === preg_match( $inner_container_start, $content, $matches, PREG_OFFSET_CAPTURE ) ) {
		$offset  = $matches[0][1];
		$content = substr( $content, 0, $offset ) . $image . substr( $content, $offset );
	}

	return $content;
}

/**
 * Registers the `core/cover` block renderer on server.
 *
 * @since 6.0.0
 */
function register_block_core_cover() {
	register_block_type_from_metadata(
		__DIR__ . '/cover',
		array(
			'render_callback' => 'render_block_core_cover',
		)
	);
}
add_action( 'init', 'register_block_core_cover' );