I am leaving for the day and will be gone for many hours. But, I searched quickly for a solution for you.
Here is a sample of adding a text-watermark using the domPDF library.
// Reference the Dompdf namespace
use Dompdf\Dompdf;
// Reference the Options namespace
use Dompdf\Options;
// Reference the Font Metrics namespace
use Dompdf\FontMetrics;
// Set options to enable embedded PHP
$options = new Options();
$options->set('isPhpEnabled', 'true');
// Instantiate dompdf class
$dompdf = new Dompdf($options);
// Load HTML content
$dompdf->loadHtml('<h1>Welcome to Adem's site!</h1>');
// (Optional) Setup the paper size and orientation
$dompdf->setPaper('A4', 'landscape');
// Render the HTML as PDF
$dompdf->render();
// Instantiate canvas instance
$canvas = $dompdf->getCanvas();
// Instantiate font metrics class
$fontMetrics = new FontMetrics($canvas, $options);
// Get height and width of page
$w = $canvas->get_width();
$h = $canvas->get_height();
// Get font family file
$font = $fontMetrics->getFont('times');
// Specify watermark text
$text = "CONFIDENTIAL";
// Get height and width of text
$txtHeight = $fontMetrics->getFontHeight($font, 75);
$textWidth = $fontMetrics->getTextWidth($text, $font, 75);
// Set text opacity
$canvas->set_opacity(.2);
// Specify horizontal and vertical position
$x = (($w-$textWidth)/2);
$y = (($h-$txtHeight)/2);
// Writes text at the specified x and y coordinates
$canvas->text($x, $y, $text, $font, 75);
// Output the generated PDF (1 = download and 0 = preview)
$dompdf->stream('document.pdf', array("Attachment" => 0));
This is a full sample to test with, so put it into a separate file and try it. It if works, then move it to your live code. Good luck! Will check back in later in my day…
