Javascript 使用MathJax转换数学公式以保存在PDF中

到目前为止-我们在WP上有在线考试web应用程序。我正在将问题纸保存为PDF格式，而不以HTML格式打开它

如果我在网页上显示问题纸，由于mathjax.js，它会适当地转换所有数学公式。当数据（问题纸）出现在网页上时，mathjax.js可以工作。但是，如果我试图保存相同的问题文件作为PDF文件，而不打开任何网页，这是行不通的。因为mathjax.js需要显示网页上的数据

我的实验- 1.当我从DB接收数据（问题纸）时，我尝试加载mathjax.js。我认为这将把公式转换回原始状态。但事实并非如此。因为，mathjax需要在网页上显示数据

如果我尝试打印数据（问题纸），它会转换公式，而不是保存为PDF。因为，这次数据在网页上

我想要什么-我希望数学公式以PDF格式显示。仅使用mathjax转换公式。所以，我只能使用mathjax将其重新转换为原始状态

如何才能做到这一点

<?php
//db connection
$dbConn = mysql_connect ("localhost", "username", "password") or die ('MySQL connect failed. ' . mysql_error());

//db selection
mysql_select_db("db_name") or die('Cannot select database. ' . mysql_error());

$id = $_REQUEST['id'];

if($_REQUEST['action'] == "print") {
    mysql_query('SET character_set_results = utf8');
    $result = mysql_query("SELECT question_id FROM wpc6_emp_exam_questions WHERE exam_id = '$id' ");
    $exam_details = mysql_fetch_assoc(mysql_query("SELECT name, duration, passing_percent, negative_marking  FROM wpc6_emp_exams WHERE id = '$id' "));
    $num = mysql_num_rows($result);
    while($row = mysql_fetch_assoc($result))
    {
        $results[] = $row['question_id'];
        $question_id = $row['question_id'];
        $result1 = mysql_query("SELECT question, option1, option2, option3, option4 FROM wpc6_emp_questions WHERE id = '$question_id' ");
        while($row1 = mysql_fetch_assoc($result1))
        {
            $results1[] = $row1;
        }

    }   
}
?>

<!-- Mathjax Script Start -->
<script type="text/javascript" src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=AM_HTMLorMML-full"></script>
<script type="text/x-mathjax-config">MathJax.Hub.Config({extensions: ["tex2jax.js"],jax: ["input/TeX", "output/HTML-CSS"],tex2jax: {inlineMath: [["$", "$"],["\\(", "\\)"]]}});</script>
<!-- Mathjax Script End -->


<?php

$html .= '
    <style>
    p, div { font-family: freeserif}
    </style>
    <div style="text-align: center;"><img src="logo_3.png"></div>
    <br/><hr><br/>

    <div style="float: left; width: 70%;">Exam - '.$exam_details['name'].'</div>
    <div style="float: right; width: 30%;">Duration - '.$exam_details['duration'].' Mins</div>
    <div style="float: left; width: 70%;">Passing Percent - '.$exam_details['passing_percent'].'</div>
    <div style="float: right; width: 30%;">Negative Marking - '.$exam_details['negative_marking'].'</div><hr>';


for($i=1; $i<=count($results1); $i++) {
    $question = $i.'. '.$results1[$i-1]['question'];
    $question = str_replace(array("\\","[","]"),"",$question);
    $question = str_replace("(","<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(",$question);
    $option1 = $results1[$i-1]['option1'];
    $option1 = str_replace(array("\\","[","]"),"",$option1);
    $option2 = $results1[$i-1]['option2'];
    $option2 = str_replace(array("\\","[","]"),"",$option2);
    $option3 = $results1[$i-1]['option3'];
    $option3 = str_replace(array("\\","[","]"),"",$option3);
    $option4 = $results1[$i-1]['option4'];
    $option4 = str_replace(array("\\","[","]"),"",$option4);

    $html .= '<p style="font-size: 12pt; font-family: freeserif "><div style="float: left; width: 100%; margin-bottom:5px; font-family: freeserif">'.$question.'</div>';

    if(strlen($option1)>40 || strlen($option2)>40 || strlen($option3)>40 || strlen($option4)>40 ) {
        $html .= '<div>(a) '.$option1.'<br/>'
            .'(b) '.$option2.'<br/>'
            .'(c) '.$option3.'<br/>'
            .'(d) '.$option4.'<br/>
        </p>';
    } else if(strlen($option1)>15 || strlen($option2)>15 || strlen($option3)>15 || strlen($option4)>15 ) {
        $html .= '<div style="float: left; width: 50%;">(a) '.$option1.'</div>'
            .'<div style="float: left; width: 50%;">(b) '.$option2.'</div>'
            .'<div style="float: left; width: 50%;">(c) '.$option3.'</div>'
            .'<div style="float: left; width: 50%;">(d) '.$option4.'</div>
        </p>';
    } else if(strlen($option1)<=15 || strlen($option2)<=15 || strlen($option3)<=15 || strlen($option4)<=15 ) {
        $html .= '<div style="float: left; width: 25%;">(a) '.$option1.'</div>'
            .'<div style="float: left; width: 25%;">(b) '.$option2.'</div>'
            .'<div style="float: left; width: 25%;">(c) '.$option3.'</div>'
            .'<div style="float: left; width: 25%;">(d) '.$option4.'</div>
        </p>';
    }
}

$html .= '<br/><br/><br/><div style="text-align: center"> --------- O &nbsp;&nbsp;Best of Luck&nbsp;&nbsp; O --------- </div>';

include("../mpdf.php");

$mpdf=new mPDF('');
$html = mb_convert_encoding($html, 'UTF-8', 'UTF-8');
$mpdf->SetWatermarkImage('logo_1.png');
$mpdf->showWatermarkImage = true;
$mpdf->WriteHTML($html);

?>

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为什么不直接传递生成的HTML？谢谢您的评论。您能详细说明一下吗？一种方法是将生成的HTML传递给mathjax节点，并将返回的HTML传递给mpdf。您只需了解如何从PHP.Ok调用NodeJS工具（或CLI工具）。谢谢我试试看。