I’m working on a Python application that generates PDFs for exams. The exam data is fetched from a server, and any math expressions in the data are stored in MathML format. I’m having trouble inserting these MathML expressions into the PDF.

I tried converting the MathML to Latex first then to image using this answer and matplotlib, it worked for simple expressions, but didn’t work with very complex ones, I guess because it doesn’t cover all MathML entities, because I keep seeing errors such as Entity not defined or expected token.
I know the MathMl that I obtained is valid because I tried rendering it on the browser and it is working.

I also tried searching for ways to insert MathML directly to avoid conversion, but couldn’t find any.

Here is an example I tried that failed.

import matplotlib.pyplot as plt
from lxml import etree

def mathml_to_tex(mathml):
    xslt = etree.parse('./mathml/mmltex.xsl')
    transform = etree.XSLT(xslt)
    mathml_tree = etree.fromstring(mathml)
    svg_tree = transform(mathml_tree)
    return str(svg_tree)


def latex_to_image(latex_code):
    fig, ax = plt.subplots(figsize=(5, 1))  
    ax.text(0.5, 0.5, latex_code, fontsize=20, ha='center', va='center')
    ax.axis('off')

    buffer = io.BytesIO()

    fig.savefig(buffer, format='png', bbox_inches='tight', pad_inches=0)
    buffer.seek(0)

    plt.close(fig)

    return buffer

def show_tex(mathml, output_file):
    tex = mathml_to_tex(mathml)
    img = latex_to_image(tex)
    with open(output_file, "wb") as temp_file:
        temp_file.write(img.read())
    

mathml_data = '''
<math xmlns="http://www.w3.org/1998/Math/MathML">
        <msqrt>
            <mi>x</mi>
            <mo> </mo>
            <mo>+</mo>
            <mo> </mo>
            <mi>y</mi>
        </msqrt>
        <mo> </mo>
        <mo>+</mo>
        <mo> </mo>
        <mfenced>
            <mtable>
                <mtr>
                    <mtd>
                        <mi>i</mi>
                    </mtd>
                    <mtd>
                        <mi>j</mi>
                    </mtd>
                    <mtd>
                        <mi>k</mi>
                    </mtd>
                </mtr>
                <mtr>
                    <mtd>
                        <mn>5</mn>
                    </mtd>
                    <mtd>
                        <mn>7</mn>
                    </mtd>
                    <mtd>
                        <mn>8</mn>
                    </mtd>
                </mtr>
                <mtr>
                    <mtd>
                        <mi>θ</mi>
                    </mtd>
                    <mtd>
                        <mi>η</mi>
                    </mtd>
                    <mtd>
                        <mi>x</mi>
                    </mtd>
                </mtr>
            </mtable>
        </mfenced>
        <mo>×</mo>
        <mo>∯</mo>
        <msub>
            <mi>log</mi>
            <mn>2</mn>
        </msub>
        <mfenced>
            <mrow>
                <mo>∂</mo>
                <mi>sin</mi>
                <mfenced>
                    <mrow>
                        <mi>ln</mi>
                        <mfenced>
                            <munderover>
                                <mo>∑</mo>
                                <mi mathvariant="fraktur">B</mi>
                                <mi mathvariant="script">B</mi>
                            </munderover>
                        </mfenced>
                    </mrow>
                </mfenced>
            </mrow>
        </mfenced>
        <mo> </mo>
        <mo>∈</mo>
        <mo> </mo>
        <mi mathvariant="normal">ℝ</mi>
        <mo> </mo>
    </math>
'''

show_tex(mathml_data, 'output.png')

ValueError: 
 sqrt{x + y} + left(begin{array}{ccc}i& j& k\ 5& 7& 8\ theta & eta & xend{array}right)times ∯{mathrm{log}}_{2}left(partial mathrm{sin}left(mathrm{ln}left(sum _{mathfrak{B}}^{mathcal{B}}right)right)right) in  mathrm{ℝ} 
                      ^
ParseSyntaxException: Expected token, found ''  (at char 22), (line:1, col:23)