ntext ) {
		return $loading_attrs;
	}

	// For now this function only supports images and iframes.
	if ( 'img' !== $tag_name && 'iframe' !== $tag_name ) {
		return $loading_attrs;
	}

	// For any resources, width and height must be provided, to avoid layout shifts.
	if ( ! isset( $attr['width'], $attr['height'] ) ) {
		return $loading_attrs;
	}

	if ( isset( $attr['loading'] ) ) {
		/*
		 * While any `loading` value could be set in `$loading_attrs`, for
		 * consistency we only do it for `loading="lazy"` since that is the
		 * only possible value that WordPress core would apply on its own.
		 */
		if ( 'lazy' === $attr['loading'] ) {
			$loading_attrs['loading'] = 'lazy';
			if ( isset( $attr['fetchpriority'] ) && 'high' === $attr['fetchpriority'] ) {
				_doing_it_wrong(
					__FUNCTION__,
					__( 'An image should not be lazy-loaded and marked as high priority at the same time.' ),
					'6.3.0'
				);
			}
		}

		return $postprocess( $loading_attrs, true );
	}

	// An image with `fetchpriority="high"` cannot be assigned `loading="lazy"` at the same time.
	if ( isset( $attr['fetchpriority'] ) && 'high' === $attr['fetchpriority'] ) {
		return $postprocess( $loading_attrs, true );
	}

	/*
	 * Do not lazy-load images in the header block template part, as they are likely above the fold.
	 * For classic themes, this is handled in the condition below using the 'get_header' action.
	 */
	$header_area = WP_TEMPLATE_PART_AREA_HEADER;
	if ( "template_part_{$header_area}" === $context ) {
		// Increase media count if there are images in header above a certian minimum size threshold.
		$maybe_increase_content_media_count();
		return $postprocess( $loading_attrs, true );
	}

	// The custom header image is always expected to be in the header.
	if ( 'get_header_image_tag' === $context ) {
		// Increase media count if there are images in header above a certian minimum size threshold.
		$maybe_increase_content_media_count();
		return $postprocess( $loading_attrs, true );
	}

	// Special handling for programmatically created image tags.
	if ( 'the_post_thumbnail' === $context || 'wp_get_attachment_image' === $context || 'widget_media_image' === $context ) {
		/*
		 * Skip programmatically created images within post content as they need to be handled together with the other
		 * images within the post content.
		 * Without this clause, they would already be considered below 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 ( doing_filter( 'the_content' ) ) {
			return $loading_attrs;
		}

		// Conditionally skip lazy-loading on images before the loop.
		if (
			// 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' )
		) {
			// Increase media count if there are images in header above a certian minimum size threshold.
			$maybe_increase_content_media_count();
			return $postprocess( $loading_attrs, true );
		}
	}

	/*
	 * The first elements in 'the_content' or 'the_post_thumbnail' should not be lazy-loaded,
	 * as they are likely above the fold. Shortcodes are processed after content images, so if
	 * thresholds haven't already been met, apply the same logic to those as well.
	 */
	if ( 'the_content' === $context || 'the_post_thumbnail' === $context || 'do_shortcode' === $context ) {
		// Only elements within the main query loop have special handling.
		if ( is_admin() || ! in_the_loop() || ! is_main_query() ) {
			$loading_attrs['loading'] = 'lazy';
			return $postprocess( $loading_attrs, false );
		}

		// Increase the counter since this is a main query content element.
		$content_media_count = wp_increase_content_media_count();

		// If the count so far is below the threshold, `loading` attribute is omitted.
		if ( $content_media_count <= wp_omit_loading_attr_threshold() ) {
			// The first largest image will still get `fetchpriority='high'`.
			return $postprocess( $loading_attrs, true );
		}
	}

	// Lazy-load by default for any unknown context.
	$loading_attrs['loading'] = 'lazy';
	return $postprocess( $loading_attrs, false );
}

/**
 * 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;
}