在pdf php中将图像水印添加到另一个图像上

我正在尝试使用fpdf和FPDI在pdf中添加 Raddyx Technologies 水印文本 . 水印出现在所有页面上，但我的水印所有页面都显示在图像下方，空间更大 . 我希望我的水印图像能够显示在pdf上的现有图像之上 . 我使用以下代码添加文本水印

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

class PDF_Rotate extends FPDI {

    var $angle = 0;

    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();
    }

}

$fullPathToFile = "recipe.pdf";

class PDF extends PDF_Rotate {

    var $_tplIdx;

    function Header() {
        global $fullPathToFile;

        //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, 'Raddyx Technologies', 45);

        if (is_null($this->_tplIdx)) {

            // THIS IS WHERE YOU GET THE NUMBER OF PAGES
            $this->numPages = $this->setSourceFile($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);
    }

}


$pdf = new PDF();
//$pdf = new FPDI();
$pdf->AddPage();
$pdf->SetFont('Arial', '', 12);


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();
?>

Socuce：https://github.com/chinmay235/php-pdf-watermark

我现有的PDF文件 - http://trackprintorders.com/recipe.pdf

Output: