Make the product box images in WordPress Simple PayPal Shopping Cart lightbox previews instead

wpspsc-create-lightbox-preview.php

/**
 * Let's make the product box images in WPSPSC lightbox previews instead
 *
 * The plugin is here: https://wordpress.org/plugins/wordpress-simple-paypal-shopping-cart
 * Using this lightbox plugin: https://wordpress.org/plugins/responsive-lightbox/
 */

function make_wpspsc_thumbs_lightbox_previews( $thumbnail, $atts ) {

	// Code Credit: http://stackoverflow.com/questions/19323324/how-to-get-image-src-attribute-value-from-php-string
	
	$doc = new DOMDocument();

	// Let's make sure we don't execute this code on the wrong elements & blow up the site
	if ( ! is_object( $doc ) ) { 
		return $thumbnail; 
	}

	libxml_use_internal_errors(true);
	$doc->loadHTML( $thumbnail );
	$xpath = new DOMXPath($doc);
	$imgs = $xpath->query("//img");
	for ($i=0; $i < $imgs->length; $i++) {
    		$img = $imgs->item($i);
    		$src = $img->getAttribute("src");
	}

	// Now let's use the image src we just got & rel="lightbox" because that's what Responsive Lightbox from dFactory uses
	$new_thumbnail = '<a href="'.$src.'" rel="lightbox">'.$thumbnail.'</a>';
	
	return $new_thumbnail;
	
}
add_filter( 'wspsc_product_box_thumbnail_code', 'make_wpspsc_thumbs_lightbox_previews' );