ขอบสอบถามพี่ๆ FPDF ไม่ทราบว่าเราจะสามารถแก้ไข text watermark ให้มันมาทับรูปภาพได้อย่างไรครับ

<?php
//This page contains edit the existing file by using fpdi.
require(dirname(__DIR__ ) . '/vendor/WatermarkPDF/WatermarkPDF.php');
# ==========================
$pdfFile = dirname(__DIR__ ) . "/Powerpoint2010.pdf";
$watermarkText = "Chinmay Kumar Sahu";
$pdf = new WatermarkPDF($pdfFile, $watermarkText);
//$pdf = new FPDI();
$pdf->AddPage();
$pdf->SetFont('Arial', '', 12);



/*$txt = "FPDF is a PHP class which allows to generate PDF files with pure PHP, that is to say " .
        "without using the PDFlib library. F from FPDF stands for Free: you may use it for any " .
        "kind of usage and modify it to suit your needs.\n\n";
for ($i = 0; $i < 25; $i++) {
    $pdf->MultiCell(0, 5, $txt, 0, 'J');
}*/


if($pdf->numPages>1) {
    for($i=2;$i<=$pdf->numPages;$i++) {
        //$pdf->endPage();
        $pdf->_tplIdx = $pdf->importPage($i);
        $pdf->AddPage();
    }
}

$pdf->Output(); //If you Leave blank then it should take default "I" i.e. Browser
//$pdf->Output("sampleUpdated.pdf", 'D'); //Download the file. open dialogue window in browser to save, not open with PDF browser viewer
//$pdf->Output("save_to_directory_path.pdf", 'F'); //save to a local file with the name given by filename (may include a path)
//$pdf->Output("sampleUpdated.pdf", 'I'); //I for "inline" to send the PDF to the browser
//$pdf->Output("", 'S'); //return the document as a string. filename is ignored.
?>

<?php
require(dirname(__DIR__) .'/fpdf/fpdf.php');
require_once dirname(__DIR__) .'/FPDI/fpdi.php';

class WatermarkPDF extends FPDI {

    public $_tplIdx;
    public $angle = 0;
    public $fullPathToFile;
    public $rotatedText = 'Muvi Entertainment Pvt. Ltd.';

    function __construct($fullPathToFile, $rotate_text) {
        $this->fullPathToFile = $fullPathToFile;
        if ($rotate_text)
            $this->rotatedText = $rotate_text;
        parent::__construct();
    }

    function Rotate($angle, $x = -1, $y = -1) {
        if ($x == -1)
            $x = $this->x;
        if ($y == -1)
            $y = $this->y;
        if ($this->angle != 0)
            $this->_out('Q');
        $this->angle = $angle;
        if ($angle != 0) {
            $angle *= M_PI / 180;
            $c = cos($angle);
            $s = sin($angle);
            $cx = $x * $this->k;
            $cy = ($this->h - $y) * $this->k;
            $this->_out(sprintf('q %.5F %.5F %.5F %.5F %.2F %.2F cm 1 0 0 1 %.2F %.2F cm', $c, $s, -$s, $c, $cx, $cy, -$cx, -$cy));
        }
    }

    function _endpage() {
        if ($this->angle != 0) {
            $this->angle = 0;
            $this->_out('Q');
        }
        parent::_endpage();
    }

    function Header() {
        //Put the watermark
        //$this->Image('http://chart.googleapis.com/chart?cht=p3&chd=t:60,40&chs=250x100&chl=Hello|World', 40, 100, 100, 0, 'PNG');
        $this->SetFont('Arial', 'B', 50);
        $this->SetTextColor(255, 192, 203);
        $this->RotatedText(20, 230, $this->rotatedText, 45);
        if ($this->fullPathToFile) {
            if (is_null($this->_tplIdx)) {
                // THIS IS WHERE YOU GET THE NUMBER OF PAGES
                $this->numPages = $this->setSourceFile($this->fullPathToFile);
                $this->_tplIdx = $this->importPage(1);
            }
            $this->useTemplate($this->_tplIdx, 0, 0, 200);
        }
    }

    function RotatedText($x, $y, $txt, $angle) {
        //Text rotated around its origin
        $this->Rotate($angle, $x, $y);
        $this->Text($x, $y, $txt);
        $this->Rotate(0);
    }

}