ld-spike-carousel.php

<?php
/**
 * Constructor
 */
public function __construct() {
	
	/**
	 * Constructor body
	 */
	 
	add_action( 'wp_enqueue_scripts', array( $this, 'enqueue_assets' ), 9 );
}

/**
 * Check widget settings and maybe change image size to smaller
 *
 * @param  string $size     Default image size.
 * @param  array  $instance Widget instance.
 * @param  array  $args     Current widget area arguments.
 * @return string
 */
public function set_image_size( $size, $instance, $args ) {

	$areas_to_rewrite = array(
		'after-content-full-width-area',
		'full-width-header-area',
	);

	$rewrite_from = 5;

	if ( ! isset( $args['id'] ) || ! in_array( $args['id'], $areas_to_rewrite ) ) {
		return $size;
	}

	if ( ! isset( $instance['slides_per_view'] ) || $rewrite_from > intval( $instance['slides_per_view'] ) ) {
		return $size;
	}

	return 'post-thumbnail';
}