How to add watermark to PDF file with PHP and FPDI for Print only?

I am using FPDF and FPDI to add current date to the existing PDF file

$pdf->Cell(0,15, date("Y/m/d"), 0, 0,'R' );

Is it possible to make it visible only when document is printed, something like Set Visibility Print Only?

(Sorry if duplicate, I'm new here)

Solution

You can use the script "Visibility" from the script section of FPDF for this purpose. Just change the class so that it extends FPDI:

class PDF_Visibility extends \setasign\Fpdi\Fpdi 
{ ...

You should know that this does not work for all PDF readers/viewers. Viewers not supporting visibility will show the content throughout.