list of media attached to the given post.
	 *
	 * @since 3.6.0
	 *
	 * @param WP_Post[] $children Array of media attached to the given post.
	 * @param string    $type     Mime type of the media desired.
	 * @param WP_Post   $post     Post object.
	 */
	return (array) apply_filters( 'get_attached_media', $children, $type, $post );
}

/**
 * Checks the HTML content for an audio, video, object, embed, or iframe tags.
 *
 * @since 3.6.0
 *
 * @param string   $content A string of HTML which might contain media elements.
 * @param string[] $types   An array of media types: 'audio', 'video', 'object', 'embed', or 'iframe'.
 * @return string[] Array of found HTML media elements.
 */
function get_media_embedded_in_content( $content, $types = null ) {
	$html = array();

	/**
	 * Filters the embedded media types that are allowed to be returned from the content blob.
	 *
	 * @since 4.2.0
	 *
	 * @param string[] $allowed_media_types An array of allowed media types. Default media types are
	 *                                      'audio', 'video', 'object', 'embed', and 'iframe'.
	 */
	$allowed_media_types = apply_filters( 'media_embedded_in_content_allowed_types', array( 'audio', 'video', 'object', 'embed', 'iframe' ) );

	if ( ! empty( $types ) ) {
		if ( ! is_array( $types ) ) {
			$types = array( $types );
		}

		$allowed_media_types = array_intersect( $allowed_media_types, $types );
	}

	$tags = implode( '|', $allowed_media_types );

	if ( preg_match_all( '#<(?P<tag>' . $tags . ')[^<]*?(?:>[\s\S]*?<\/(?P=tag)>|\s*\/>)#', $content, $matches ) ) {
		foreach ( $matches[0] as $match ) {
			$html[] = $match;
		}
	}

	return $html;
}

/**
 * Retrieves galleries from the passed post's content.
 *
 * @since 3.6.0
 *
 * @param int|WP_Post $post Post ID or object.
 * @param bool        $html Optional. Whether to return HTML or data in the array. Default true.
 * @return array A list of arrays, each containing gallery data and srcs parsed
 *               from the expanded shortcode.
 */
function get_post_galleries( $post, $html = true ) {
	$post = get_post( $post );

	if ( ! $post ) {
		return array();
	}

	if ( ! has_shortcode( $post->post_content, 'gallery' ) && ! has_block( 'gallery', $post->post_content ) ) {
		return array();
	}

	$galleries = array();
	if ( preg_match_all( '/' . get_shortcode_regex() . '/s', $post->post_content, $matches, PREG_SET_ORDER ) ) {
		foreach ( $matches as $shortcode ) {
			if ( 'gallery' === $shortcode[2] ) {
				$srcs = array();

				$shortcode_attrs = shortcode_parse_atts( $shortcode[3] );
				if ( ! is_array( $shortcode_attrs ) ) {
					$shortcode_attrs = array();
				}

				// Specify the post ID of the gallery we're viewing if the shortcode doesn't reference another post already.
				if ( ! isset( $shortcode_attrs['id'] ) ) {
					$shortcode[3] .= ' id="' . (int) $post->ID . '"';
				}

				$gallery = do_shortcode_tag( $shortcode );
				if ( $html ) {
					$galleries[] = $gallery;
				} else {
					preg_match_all( '#src=([\'"])(.+?)\1#is', $gallery, $src, PREG_SET_ORDER );
					if ( ! empty( $src ) ) {
						foreach ( $src as $s ) {
							$srcs[] = $s[2];
						}
					}

					$galleries[] = array_merge(
						$shortcode_attrs,
						array(
							'src' => array_values( array_unique( $srcs ) ),
						)
					);
				}
			}
		}
	}

	if ( has_block( 'gallery', $post->post_content ) ) {
		$post_blocks = parse_blocks( $post->post_content );

		while ( $block = array_shift( $post_blocks ) ) {
			$has_inner_blocks = ! empty( $block['innerBlocks'] );

			// Skip blocks with no blockName and no innerHTML.
			if ( ! $block['blockName'] ) {
				continue;
			}

			// Skip non-Gallery blocks.
			if ( 'core/gallery' !== $block['blockName'] ) {
				// Move inner blocks into the root array before skipping.
				if ( $has_inner_blocks ) {
					array_push( $post_blocks, ...$block['innerBlocks'] );
				}
				continue;
			}

			// New Gallery block format as HTML.
			if ( $has_inner_blocks && $html ) {
				$block_html  = wp_list_pluck( $block['innerBlocks'], 'innerHTML' );
				$galleries[] = '<figure>' . implode( ' ', $block_html ) . '</figure>';
				continue;
			}

			$srcs = array();

			// New Gallery block format as an array.
			if ( $has_inner_blocks ) {
				$attrs = wp_list_pluck( $block['innerBlocks'], 'attrs' );
				$ids   = wp_list_pluck( $attrs, 'id' );

				foreach ( $ids as $id ) {
					$url = wp_get_attachment_url( $id );

					if ( is_string( $url ) && ! in_array( $url, $srcs, true ) ) {
						$srcs[] = $url;
					}
				}

				$galleries[] = array(
					'ids' => implode( ',', $ids ),
					'src' => $srcs,
				);

				continue;
			}

			// Old Gallery block format as HTML.
			if ( $html ) {
				$galleries[] = $block['innerHTML'];
				continue;
			}

			// Old Gallery block format as an array.
			$ids = ! empty( $block['attrs']['ids'] ) ? $block['attrs']['ids'] : array();

			// If present, use the image IDs from the JSON blob as canonical.
			if ( ! empty( $ids ) ) {
				foreach ( $ids as $id ) {
					$url = wp_get_attachment_url( $id );

					if ( is_string( $url ) && ! in_array( $url, $srcs, true ) ) {
						$srcs[] = $url;
					}
				}

				$galleries[] = array(
					'ids' => implode( ',', $ids ),
					'src' => $srcs,
				);

				continue;
			}

			// Otherwise, extract srcs from the innerHTML.
			preg_match_all( '#src=([\'"])(.+?)\1#is', $block['innerHTML'], $found_srcs, PREG_SET_ORDER );

			if ( ! empty( $found_srcs[0] ) ) {
				foreach ( $found_srcs as $src ) {
					if ( isset( $src[2] ) && ! in_array( $src[2], $srcs, true ) ) {
						$srcs[] = $src[2];
					}
				}
			}

			$galleries[] = array( 'src' => $srcs );
		}
	}

	/**
	 * Filters the list of all found galleries in the given post.
	 *
	 * @since 3.6.0
	 *
	 * @param array   $galleries Associative array of all found post galleries.
	 * @param WP_Post $post      Post object.
	 */
	return apply_filters( 'get_post_galleries', $galleries, $post );
}

/**
 * Checks a specified post's content for gallery and, if present, return the first
 *
 * @since 3.6.0
 *
 * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global $post.
 * @param bool        $html Optional. Whether to return HTML or data. Default is true.
 * @return string|array Gallery data and srcs parsed from the expanded shortcode.
 */
function get_post_gallery( $post = 0, $html = true ) {
	$galleries = get_post_galleries( $post, $html );
	$gallery   = reset( $galleries );

	/**
	 * Filters the first-found post gallery.
	 *
	 * @since 3.6.0
	 *
	 * @param array       $gallery   The first-found post gallery.
	 * @param int|WP_Post $post      Post ID or object.
	 * @param array       $galleries Associative array of all found post galleries.
	 */
	return apply_filters( 'get_post_gallery', $gallery, $post, $galleries );
}

/**
 * Retrieves the image srcs from galleries from a post's content, if present.
 *
 * @since 3.6.0
 *
 * @see get_post_galleries()
 *
 * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`.
 * @return array A list of lists, each containing image srcs parsed.
 *               from an expanded shortcode
 */
function get_post_galleries_images( $post = 0 ) {
	$galleries = get_post_galleries( $post, false );
	return wp_list_pluck( $galleries, 'src' );
}

/**
 * Checks a post's content for galleries and return the image srcs for the first found gallery.
 *
 * @since 3.6.0
 *
 * @see get_post_gallery()
 *
 * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`.
 * @return string[] A list of a gallery's image srcs in order.
 */
function get_post_gallery_images( $post = 0 ) {
	$gallery = get_post_gallery( $post, false );
	return empty( $gallery['src'] ) ? array() : $gallery['src'];
}

/**
 * Maybe attempts to generate attachment metadata, if missing.
 *
 * @since 3.9.0
 *
 * @param WP_Post $attachment Attachment object.
 */
function wp_maybe_generate_attachment_metadata( $attachment ) {
	if ( empty( $attachment ) || empty( $attachment->ID ) ) {
		return;
	}

	$attachment_id = (int) $attachment->ID;
	$file          = get_attached_file( $attachment_id );
	$meta          = wp_get_attachment_metadata( $attachment_id );

	if ( empty( $meta ) && file_exists( $file ) ) {
		$_meta = get_post_meta( $attachment_id );
		$_lock = 'wp_generating_att_' . $attachment_id;

		if ( ! array_key_exists( '_wp_attachment_metadata', $_meta ) && ! get_transient( $_lock ) ) {
			set_transient( $_lock, $file );
			wp_update_attachment_metadata( $attachment_id, wp_generate_attachment_metadata( $attachment_id, $file ) );
			delete_transient( $_lock );
		}
	}
}

/**
 * Tries to convert an attachment URL into a post ID.
 *
 * @since 4.0.0
 *
 * @global wpdb $wpdb WordPress database abstraction object.
 *
 * @param string $url The URL to resolve.
 * @return int The found post ID, or 0 on failure.
 */
function attachment_url_to_postid( $url ) {
	global $wpdb;

	$dir  = wp_get_upload_dir();
	$path = $url;

	$site_url   = parse_url( $dir['url'] );
	$image_path = parse_url( $path );

	// Force the protocols to match if needed.
	if ( isset( $image_path['scheme'] ) && ( $image_path['scheme'] !== $site_url['scheme'] ) ) {
		$path = str_replace( $image_path['scheme'], $site_url['scheme'], $path );
	}

	if ( str_starts_with( $path, $dir['baseurl'] . '/' ) ) {
		$path = substr( $path, strlen( $dir['baseurl'] . '/' ) );
	}

	$sql = $wpdb->prepare(
		"SELECT post_id, meta_value FROM $wpdb->postmeta WHERE meta_key = '_wp_attached_file' AND meta_value = %s",
		$path
	);

	$results = $wpdb->get_results( $sql );
	$post_id = null;

	if ( $results ) {
		// Use the first available result, but prefer a case-sensitive match, if exists.
		$post_id = reset( $results )->post_id;

		if ( count( $results ) > 1 ) {
			foreach ( $results as $result ) {
				if ( $path === $result->meta_value ) {
					$post_id = $result->post_id;
					break;
				}
			}
		}
	}

	/**
	 * Filters an attachment ID found by URL.
	 *
	 * @since 4.2.0
	 *
	 * @param int|null $post_id The post_id (if any) found by the function.
	 * @param string   $url     The URL being looked up.
	 */
	return (int) apply_filters( 'attachment_url_to_postid', $post_id, $url );
}

/**
 * Returns the URLs for CSS files used in an iframe-sandbox'd TinyMCE media view.
 *
 * @since 4.0.0
 *
 * @return string[] The relevant CSS file URLs.
 */
function wpview_media_sandbox_styles() {
	$version        = 'ver=' . get_bloginfo( 'version' );
	$mediaelement   = includes_url( "js/mediaelement/mediaelementplayer-legacy.min.css?$version" );
	$wpmediaelement = includes_url( "js/mediaelement/wp-mediaelement.css?$version" );

	return array( $mediaelement, $wpmediaelement );
}

/**
 * Registers the personal data exporter for media.
 *
 * @param array[] $exporters An array of personal data exporters, keyed by their ID.
 * @return array[] Updated array of personal data exporters.
 */
function wp_register_media_personal_data_exporter( $exporters ) {
	$exporters['wordpress-media'] = array(
		'exporter_friendly_name' => __( 'WordPress Media' ),
		'callback'               => 'wp_media_personal_data_exporter',
	);

	return $exporters;
}

/**
 * Finds and exports attachments associated with an email address.
 *
 * @since 4.9.6
 *
 * @param string $email_address The attachment owner email address.
 * @param int    $page          Attachment page number.
 * @return array {
 *     An array of personal data.
 *
 *     @type array[] $data An array of personal data arrays.
 *     @type bool    $done Whether the exporter is finished.
 * }
 */
function wp_media_personal_data_exporter( $email_address, $page = 1 ) {
	// Limit us to 50 attachments at a time to avoid timing out.
	$number = 50;
	$page   = (int) $page;

	$data_to_export = array();

	$user = get_user_by( 'email', $email_address );
	if ( false === $user ) {
		return array(
			'data' => $data_to_export,
			'done' => true,
		);
	}

	$post_query = new WP_Query(
		array(
			'author'         => $user->ID,
			'posts_per_page' => $number,
			'paged'          => $page,
			'post_type'      => 'attachment',
			'post_status'    => 'any',
			'orderby'        => 'ID',
			'order'          => 'ASC',
		)
	);

	foreach ( (array) $post_query->posts as $post ) {
		$attachment_url = wp_get_attachment_url( $post->ID );

		if ( $attachment_url ) {
			$post_data_to_export = array(
				array(
					'name'  => __( 'URL' ),
					'value' => $attachment_url,
				),
			);

			$data_to_export[] = array(
				'group_id'          => 'media',
				'group_label'       => __( 'Media' ),
				'group_description' => __( 'User&#8217;s media data.' ),
				'item_id'           => "post-{$post->ID}",
				'data'              => $post_data_to_export,
			);
		}
	}

	$done = $post_query->max_num_pages <= $page;

	return array(
		'data' => $data_to_export,
		'done' => $done,
	);
}

/**
 * Adds additional default image sub-sizes.
 *
 * These sizes are meant to enhance the way WordPress displays images on the front-end on larger,
 * high-density devices. They make it possible to generate more suitable `srcset` and `sizes` attributes
 * when the users upload large images.
 *
 * The sizes can be changed or removed by themes and plugins but that is not recommended.
 * The size "names" reflect the image dimensions, so changing the sizes would be quite misleading.
 *
 * @since 5.3.0
 * @access private
 */
function _wp_add_additional_image_sizes() {
	// 2x medium_large size.
	add_image_size( '1536x1536', 1536, 1536 );
	// 2x large size.
	add_image_size( '2048x2048', 2048, 2048 );
}

/**
 * Callback to enable showing of the user error when uploading .heic images.
 *
 * @since 5.5.0
 *
 * @param array[] $plupload_settings The settings for Plupload.js.
 * @return array[] Modified settings for Plupload.js.
 */
function wp_show_heic_upload_error( $plupload_settings ) {
	$plupload_settings['heic_upload_error'] = true;
	return $plupload_settings;
}

/**
 * Allows PHP's getimagesize() to be debuggable when necessary.
 *
 * @since 5.7.0
 * @since 5.8.0 Added support for WebP images.
 *
 * @param string $filename   The file path.
 * @param array  $image_info Optional. Extended image information (passed by reference).
 * @return array|false Array of image information or false on failure.
 */
function wp_getimagesize( $filename, array &$image_info = null ) {
	// Don't silence errors when in debug mode, unless running unit tests.
	if ( defined( 'WP_DEBUG' ) && WP_DEBUG
		&& ! defined( 'WP_RUN_CORE_TESTS' )
	) {
		if ( 2 === func_num_args() ) {
			$info = getimagesize( $filename, $image_info );
		} else {
			$info = getimagesize( $filename );
		}
	} else {
		/*
		 * Silencing notice and warning is intentional.
		 *
		 * getimagesize() has a tendency to generate errors, such as
		 * "corrupt JPEG data: 7191 extraneous bytes before marker",
		 * even when it's able to provide image size information.
		 *
		 * See https://core.trac.wordpress.org/ticket/42480
		 */
		if ( 2 === func_num_args() ) {
			$info = @getimagesize( $filename, $image_info );
		} else {
			$info = @getimagesize( $filename );
		}
	}

	if ( false !== $info ) {
		return $info;
	}

	/*
	 * For PHP versions that don't support WebP images,
	 * extract the image size info from the file headers.
	 */
	if ( 'image/webp' === wp_get_image_mime( $filename ) ) {
		$webp_info = wp_get_webp_info( $filename );
		$width     = $webp_info['width'];
		$height    = $webp_info['height'];

		// Mimic the native return format.
		if ( $width && $height ) {
			return array(
				$width,
				$height,
				IMAGETYPE_WEBP,
				sprintf(
					'width="%d" height="%d"',
					$width,
					$height
				),
				'mime' => 'image/webp',
			);
		}
	}

	// The image could not be parsed.
	return false;
}

/**
 * Extracts meta information about a WebP file: width, height, and type.
 *
 * @since 5.8.0
 *
 * @param string $filename Path to a WebP file.
 * @return array {
 *     An array of WebP image information.
 *
 *     @type int|false    $width  Image width on success, false on failure.
 *     @type int|false    $height Image height on success, false on failure.
 *     @type string|false $type   The WebP type: one of 'lossy', 'lossless' or 'animated-alpha'.
 *                                False on failure.
 * }
 */
function wp_get_webp_info( $filename ) {
	$width  = false;
	$height = false;
	$type   = false;

	if ( 'image/webp' !== wp_get_image_mime( $filename ) ) {
		return compact( 'width', 'height', 'type' );
	}

	$magic = file_get_contents( $filename, false, null, 0, 40 );

	if ( false === $magic ) {
		return compact( 'width', 'height', 'type' );
	}

	// Make sure we got enough bytes.
	if ( strlen( $magic ) < 40 ) {
		return compact( 'width', 'height', 'type' );
	}

	/*
	 * The headers are a little different for each of the three formats.
	 * Header values based on WebP docs, see https://developers.google.com/speed/webp/docs/riff_container.
	 */
	switch ( substr( $magic, 12, 4 ) ) {
		// Lossy WebP.
		case 'VP8 ':
			$parts  = unpack( 'v2', substr( $magic, 26, 4 ) );
			$width  = (int) ( $parts[1] & 0x3FFF );
			$height = (int) ( $parts[2] & 0x3FFF );
			$type   = 'lossy';
			break;
		// Lossless WebP.
		case 'VP8L':
			$parts  = unpack( 'C4', substr( $magic, 21, 4 ) );
			$width  = (int) ( $parts[1] | ( ( $parts[2] & 0x3F ) << 8 ) ) + 1;
			$height = (int) ( ( ( $parts[2] & 0xC0 ) >> 6 ) | ( $parts[3] << 2 ) | ( ( $parts[4] & 0x03 ) << 10 ) ) + 1;
			$type   = 'lossless';
			break;
		// Animated/alpha WebP.
		case 'VP8X':
			// Pad 24-bit int.
			$width = unpack( 'V', substr( $magic, 24, 3 ) . "\x00" );
			$width = (int) ( $width[1] & 0xFFFFFF ) + 1;
			// Pad 24-bit int.
			$height = unpack( 'V', substr( $magic, 27, 3 ) . "\x00" );
			$height = (int) ( $height[1] & 0xFFFFFF ) + 1;
			$type   = 'animated-alpha';
			break;
	}

	return compact( 'width', 'height', 'type' );
}

/**
 * Gets loading optimization attributes.
 *
 * This function returns an array of attributes that should be merged into the given attributes array to optimize
 * loading performance. Potential attributes returned by this function are:
 * - `loading` attribute with a value of "lazy"
 * - `fetchpriority` attribute with a value of "high"
 * - `decoding` attribute with a value of "async"
 *
 * If any of these attributes are already present in the given attributes, they will not be modified. Note that no
 * element should have both `loading="lazy"` and `fetchpriority="high"`, so the function will trigger a warning in case
 * both attributes are present with those values.
 *
 * @since 6.3.0
 *
 * @global WP_Query $wp_query WordPress Query object.
 *
 * @param string $tag_name The tag name.
 * @param array  $attr     Array of the attributes for the tag.
 * @param string $context  Context for the element for which the loading optimization attribute is requested.
 * @return array Loading optimization attributes.
 */
function wp_get_loading_optimization_attributes( $tag_name, $attr, $context ) {
	global $wp_query;

	/**
	 * Filters whether to short-circuit loading optimization attributes.
	 *
	 * Returning an array from the filter will effectively short-circuit the loading of optimization attributes,
	 * returning that value instead.
	 *
	 * @since 6.4.0
	 *
	 * @param array|false $loading_attrs False by default, or array of loading optimization attributes to short-circuit.
	 * @param string      $tag_name      The tag name.
	 * @param array       $attr          Array of the attributes for the tag.
	 * @param string      $context       Context for the element for which the loading optimization attribute is requested.
	 */
	$loading_attrs = apply_filters( 'pre_wp_get_loading_optimization_attributes', false, $tag_name, $attr, $context );

	if ( is_array( $loading_attrs ) ) {
		return $loading_attrs;
	}

	$loading_attrs = array();

	/*
	 * Skip lazy-loading for the overall block template, as it is handled more granularly.
	 * The skip is also applicable for `fetchpriority`.
	 */
	if ( 'template' === $context ) {
		/** This filter is documented in wp-includes/media.php */
		return apply_filters( 'wp_get_loading_optimization_attributes', $loading_attrs, $tag_name, $attr, $context );
	}

	// For now this function only supports images and iframes.
	if ( 'img' !== $tag_name && 'iframe' !== $tag_name ) {
		/** This filter is documented in wp-includes/media.php */
		return apply_filters( 'wp_get_loading_optimization_attributes', $loading_attrs, $tag_name, $attr, $context );
	}

	/*
	 * Skip programmatically created images within content blobs as they need to be handled together with the other
	 * images within the post content or widget content.
	 * Without this clause, they would already be considered within their own context which skews the image count and
	 * can result in the first post content image being lazy-loaded or an image further down the page being marked as a
	 * high priority.
	 */
	if (
		'the_content' !== $context && doing_filter( 'the_content' ) ||
		'widget_text_content' !== $context && doing_filter( 'widget_text_content' ) ||
		'widget_block_content' !== $context && doing_filter( 'widget_block_content' )
	) {
		/** This filter is documented in wp-includes/media.php */
		return apply_filters( 'wp_get_loading_optimization_attributes', $loading_attrs, $tag_name, $attr, $context );

	}

	/*
	 * Add `decoding` with a value of "async" for every image unless it has a
	 * conflicting `decoding` attribute already present.
	 */
	if ( 'img' === $tag_name ) {
		if ( isset( $attr['decoding'] ) ) {
			$loading_attrs['decoding'] = $attr['decoding'];
		} else {
			$loading_attrs['decoding'] = 'async';
		}
	}

	// For any resources, width and height must be provided, to avoid layout shifts.
	if ( ! isset( $attr['width'], $attr['height'] ) ) {
		/** This filter is documented in wp-includes/media.php */
		return apply_filters( 'wp_get_loading_optimization_attributes', $loading_attrs, $tag_name, $attr, $context );
	}

	/*
	 * The key function logic starts here.
	 */
	$maybe_in_viewport    = null;
	$increase_count       = false;
	$maybe_increase_count = false;

	// Logic to handle a `loading` attribute that is already provided.
	if ( isset( $attr['loading'] ) ) {
		/*
		 * Interpret "lazy" as not in viewport. Any other value can be
		 * interpreted as in viewport (realistically only "eager" or `false`
		 * to force-omit the attribute are other potential values).
		 */
		if ( 'lazy' === $attr['loading'] ) {
			$maybe_in_viewport = false;
		} else {
			$maybe_in_viewport = true;
		}
	}

	// Logic to handle a `fetchpriority` attribute that is already provided.
	if ( isset( $attr['fetchpriority'] ) && 'high' === $attr['fetchpriority'] ) {
		/*
		 * If the image was already determined to not be in the viewport (e.g.
		 * from an already provided `loading` attribute), trigger a warning.
		 * Otherwise, the value can be interpreted as in viewport, since only
		 * the most important in-viewport image should have `fetchpriority` set
		 * to "high".
		 */
		if ( false === $maybe_in_viewport ) {
			_doing_it_wrong(
				__FUNCTION__,
				__( 'An image should not be lazy-loaded and marked as high priority at the same time.' ),
				'6.3.0'
			);
			/*
			 * Set `fetchpriority` here for backward-compatibility as we should
			 * not override what a developer decided, even though it seems
			 * incorrect.
			 */
			$loading_attrs['fetchpriority'] = 'high';
		} else {
			$maybe_in_viewport = true;
		}
	}

	if ( null === $maybe_in_viewport ) {
		$header_enforced_contexts = array(
			'template_part_' . WP_TEMPLATE_PART_AREA_HEADER => true,
			'get_header_image_tag' => true,
		);

		/**
		 * Filters the header-specific contexts.
		 *
		 * @since 6.4.0
		 *
		 * @param array $default_header_enforced_contexts Map of contexts for which elements should be considered
		 *                                                in the header of the page, as $context => $enabled
		 *                                                pairs. The $enabled should always be true.
		 */
		$header_enforced_contexts = apply_filters( 'wp_loading_optimization_force_header_contexts', $header_enforced_contexts );

		// Consider elements with these header-specific contexts to be in viewport.
		if ( isset( $header_enforced_contexts[ $context ] ) ) {
			$maybe_in_viewport    = true;
			$maybe_increase_count = true;
		} elseif ( ! is_admin() && in_the_loop() && is_main_query() ) {
			/*
			 * Get the content media count, since this is a main query
			 * content element. This is accomplished by "increasing"
			 * the count by zero, as the only way to get the count is
			 * to call this function.
			 * The actual count increase happens further below, based
			 * on the `$increase_count` flag set here.
			 */
			$content_media_count = wp_increase_content_media_count( 0 );
			$increase_count      = true;

			// If the count so far is below the threshold, `loading` attribute is omitted.
			if ( $content_media_count < wp_omit_loading_attr_threshold() ) {
				$maybe_in_viewport = true;
			} else {
				$maybe_in_viewport = false;
			}
		} elseif (
			// Only apply for main query but before the loop.
			$wp_query->before_loop && $wp_query->is_main_query()
			/*
			 * Any image before the loop, but after the header has started should not be lazy-loaded,
			 * except when the footer has already started which can happen when the current template
			 * does not include any loop.
			 */
			&& did_action( 'get_header' ) && ! did_action( 'get_footer' )
			) {
			$maybe_in_viewport    = true;
			$maybe_increase_count = true;
		}
	}

	/*
	 * If the element is in the viewport (`true`), potentially add
	 * `fetchpriority` with a value of "high". Otherwise, i.e. if the element
	 * is not not in the viewport (`false`) or it is unknown (`null`), add
	 * `loading` with a value of "lazy".
	 */
	if ( $maybe_in_viewport ) {
		$loading_attrs = wp_maybe_add_fetchpriority_high_attr( $loading_attrs, $tag_name, $attr );
	} else {
		// Only add `loading="lazy"` if the feature is enabled.
		if ( wp_lazy_loading_enabled( $tag_name, $context ) ) {
			$loading_attrs['loading'] = 'lazy';
		}
	}

	/*
	 * If flag was set based on contextual logic above, increase the content
	 * media count, either unconditionally, or based on whether the image size
	 * is larger than the threshold.
	 */
	if ( $increase_count ) {
		wp_increase_content_media_count();
	} elseif ( $maybe_increase_count ) {
		/** This filter is documented in wp-includes/media.php */
		$wp_min_priority_img_pixels = apply_filters( 'wp_min_priority_img_pixels', 50000 );

		if ( $wp_min_priority_img_pixels <= $attr['width'] * $attr['height'] ) {
			wp_increase_content_media_count();
		}
	}

	/**
	 * Filters the loading optimization attributes.
	 *
	 * @since 6.4.0
	 *
	 * @param array  $loading_attrs The loading optimization attributes.
	 * @param string $tag_name      The tag name.
	 * @param array  $attr          Array of the attributes for the tag.
	 * @param string $context       Context for the element for which the loading optimization attribute is requested.
	 */
	return apply_filters( 'wp_get_loading_optimization_attributes', $loading_attrs, $tag_name, $attr, $context );
}

/**
 * Gets the threshold for how many of the first content media elements to not lazy-load.
 *
 * This function runs the {@see 'wp_omit_loading_attr_threshold'} filter, which uses a default threshold value of 3.
 * The filter is only run once per page load, unless the `$force` parameter is used.
 *
 * @since 5.9.0
 *
 * @param bool $force Optional. If set to true, the filter will be (re-)applied even if it already has been before.
 *                    Default false.
 * @return int The number of content media elements to not lazy-load.
 */
function wp_omit_loading_attr_threshold( $force = false ) {
	static $omit_threshold;

	// This function may be called multiple times. Run the filter only once per page load.
	if ( ! isset( $omit_threshold ) || $force ) {
		/**
		 * Filters the threshold for how many of the first content media elements to not lazy-load.
		 *
		 * For these first content media elements, the `loading` attribute will be omitted. By default, this is the case
		 * for only the very first content media element.
		 *
		 * @since 5.9.0
		 * @since 6.3.0 The default threshold was changed from 1 to 3.
		 *
		 * @param int $omit_threshold The number of media elements where the `loading` attribute will not be added. Default 3.
		 */
		$omit_threshold = apply_filters( 'wp_omit_loading_attr_threshold', 3 );
	}

	return $omit_threshold;
}

/**
 * Increases an internal content media count variable.
 *
 * @since 5.9.0
 * @access private
 *
 * @param int $amount Optional. Amount to increase by. Default 1.
 * @return int The latest content media count, after the increase.
 */
function wp_increase_content_media_count( $amount = 1 ) {
	static $content_media_count = 0;

	$content_media_count += $amount;

	return $content_media_count;
}

/**
 * Determines whether to add `fetchpriority='high'` to loading attributes.
 *
 * @since 6.3.0
 * @access private
 *
 * @param array  $loading_attrs Array of the loading optimization attributes for the element.
 * @param string $tag_name      The tag name.
 * @param array  $attr          Array of the attributes for the element.
 * @return array Updated loading optimization attributes for the element.
 */
function wp_maybe_add_fetchpriority_high_attr( $loading_attrs, $tag_name, $attr ) {
	// For now, adding `fetchpriority="high"` is only supported for images.
	if ( 'img' !== $tag_name ) {
		return $loading_attrs;
	}

	if ( isset( $attr['fetchpriority'] ) ) {
		/*
		 * While any `fetchpriority` value could be set in `$loading_attrs`,
		 * for consistency we only do it for `fetchpriority="high"` since that
		 * is the only possible value that WordPress core would apply on its
		 * own.
		 */
		if ( 'high' === $attr['fetchpriority'] ) {
			$loading_attrs['fetchpriority'] = 'high';
			wp_high_priority_element_flag( false );
		}

		return $loading_attrs;
	}

	// Lazy-loading and `fetchpriority="high"` are mutually exclusive.
	if ( isset( $loading_attrs['loading'] ) && 'lazy' === $loading_attrs['loading'] ) {
		return $loading_attrs;
	}

	if ( ! wp_high_priority_element_flag() ) {
		return $loading_attrs;
	}

	/**
	 * Filters the minimum square-pixels threshold for an image to be eligible as the high-priority image.
	 *
	 * @since 6.3.0
	 *
	 * @param int $threshold Minimum square-pixels threshold. Default 50000.
	 */
	$wp_min_priority_img_pixels = apply_filters( 'wp_min_priority_img_pixels', 50000 );

	if ( $wp_min_priority_img_pixels <= $attr['width'] * $attr['height'] ) {
		$loading_attrs['fetchpriority'] = 'high';
		wp_high_priority_element_flag( false );
	}

	return $loading_attrs;
}

/**
 * Accesses a flag that indicates if an element is a possible candidate for `fetchpriority='high'`.
 *
 * @since 6.3.0
 * @access private
 *
 * @param bool $value Optional. Used to change the static variable. Default null.
 * @return bool Returns true if high-priority element was marked already, otherwise false.
 */
function wp_high_priority_element_flag( $value = null ) {
	static $high_priority_element = true;

	if ( is_bool( $value ) ) {
		$high_priority_element = $value;
	}

	return $high_priority_element;
}