wp_maybe_add_fetchpriority_high_attr( array $loading_attrs, string $tag_name, array $attr ): array

Source

 * 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'] ) {

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