Adding custom text to PDF Invoices & Packing Slips for WooCommerce

functions.php

<?php 

/**
 * Add this to your theme's functions.php file to display text on the PDF template.
 * 
 * Options for positioning the text:
 * - wpo_wcpdf_before_document
 * - wpo_wcpdf_before_shop_address
 * - wpo_wcpdf_after_shop_address
 * - wpo_wcpdf_before_shop_logo
 * - wpo_wcpdf_after_shop_logo
 * - wpo_wcpdf_before_shop_name
 * - wpo_wcpdf_after_shop_name
 * - wpo_wcpdf_before_document_label
 * - wpo_wcpdf_after_document_label
 * - wpo_wcpdf_before_billing_address
 * - wpo_wcpdf_after_billing_address
 * - wpo_wcpdf_before_shipping_address
 * - wpo_wcpdf_after_shipping_address
 * - wpo_wcpdf_before_order_data
 * - wpo_wcpdf_before_order_details
 * - wpo_wcpdf_templates_before_order_details_row
 * - wpo_wcpdf_templates_after_order_details_row
 * - wpo_wcpdf_before_document_notes
 * - wpo_wcpdf_after_document_notes
 * - wpo_wcpdf_before_customer_notes
 * - wpo_wcpdf_after_customer_notes
 * - wpo_wcpdf_after_order_details
 * - wpo_wcpdf_after_document
 */
function wpo_wcpdf_add_custom_text_for_email_invoice_gateway( $type, $order ) {
	if( $order->get_payment_method() === 'wcpos_email_invoice' ) {
		echo '<div style="text-align: center; font-weight: bold;">Gelieve de rekening binnen 8 dagen te betalen.</div>';
	}
}

add_action( 'wpo_wcpdf_after_order_details', 'wpo_wcpdf_add_custom_text_for_email_invoice_gateway', 10, 2);