如何通过php将文件作为附件嵌入到pdf文件中？

require('fpdf.php');

class PDF extends FPDF {
    function Header() {
        // 设置页眉内容
    }
    
    function Footer() {
        // 设置页脚内容
    }
}

function addAttachment($filePath, $attachmentName) {
    $fileContent = file_get_contents($filePath);
    $this->AddAttachment($fileContent, $attachmentName);
}

function generatePDF($filePath) {
    $this->AddPage();
    // 添加PDF内容
    
    $this->Output($filePath, 'F');
}

$pdf = new PDF();
$pdf->addAttachment('path/to/file.pdf', 'Attachment.pdf');

$pdf->generatePDF('output.pdf');