Publishing to XML

[psychemedia]

It's possible to generate a Sphinx XML representation of a book using a custom builder:

jb build . --builder custom --custom-builder xml

Code in notebooks or Jupytext prefixed markdown can be executed and text outputs make it into the generated XML, but if image assets are generated, for example, code generated matplotlib charts, this are not handled:

        <paragraph>For example, we can create a simple data table:</paragraph>
        <container cell_index="1" cell_metadata="{}" classes="cell" exec_count="3" nb_element="cell_code">
            <container classes="cell_input" nb_element="cell_code_source">
                <literal_block language="ipython3" linenos="False" xml:space="preserve">import pandas as pd

df = pd.DataFrame({"x": [1, 2, 3], "y":[10,3, 7]})
df</literal_block>
            </container>
            <container classes="cell_output" nb_element="cell_code_output">
                <literal_block classes="output text_plain" language="myst-ansi" linenos="False" xml:space="preserve">   x   y
0  1  10
1  2   3
2  3   7</literal_block>
            </container>
        </container>
        <paragraph>And then generate a simple plot from the data:</paragraph>
        <container cell_index="3" cell_metadata="{}" classes="cell" exec_count="10" nb_element="cell_code">
            <container classes="cell_input" nb_element="cell_code_source">
                <literal_block language="ipython3" linenos="False" xml:space="preserve">df.plot(x="x", y="y").set_title("My plot");</literal_block>
            </container>
            <container classes="cell_output" nb_element="cell_code_output">
                <literal_block classes="output text_plain" language="myst-ansi" linenos="False" xml:space="preserve">&lt;Figure size 640x480 with 1 Axes&gt;</literal_block>
            </container>
        </container>
        <paragraph>The output chart is rendered to an image created directly from the data in the dataframe.</paragraph>

The equivalent generated HTML is:

<p>For example, we can create a simple data table:</p>
<div class="cell docutils container">
<div class="cell_input docutils container">
<div class="highlight-ipython3 notranslate"><div class="highlight"><pre><span></span><span class="kn">import</span> <span class="nn">pandas</span> <span class="k">as</span> <span class="nn">pd</span>

<span class="n">df</span> <span class="o">=</span> <span class="n">pd</span><span class="o">.</span><span class="n">DataFrame</span><span class="p">({</span><span class="s2">&quot;x&quot;</span><span class="p">:</span> <span class="p">[</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">],</span> <span class="s2">&quot;y&quot;</span><span class="p">:[</span><span class="mi">10</span><span class="p">,</span><span class="mi">3</span><span class="p">,</span> <span class="mi">7</span><span class="p">]})</span>
<span class="n">df</span>
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<div class="output text_html"><div>
<style scoped>
    .dataframe tbody tr th:only-of-type {
        vertical-align: middle;
    }

    .dataframe tbody tr th {
        vertical-align: top;
    }

    .dataframe thead th {
        text-align: right;
    }
</style>
<table border="1" class="dataframe">
  <thead>
    <tr style="text-align: right;">
      <th></th>
      <th>x</th>
      <th>y</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <th>0</th>
      <td>1</td>
      <td>10</td>
    </tr>
    <tr>
      <th>1</th>
      <td>2</td>
      <td>3</td>
    </tr>
    <tr>
      <th>2</th>
      <td>3</td>
      <td>7</td>
    </tr>
  </tbody>
</table>
</div></div></div>
</div>
<p>And then generate a simple plot from the data:</p>
<div class="cell docutils container">
<div class="cell_input docutils container">
<div class="highlight-ipython3 notranslate"><div class="highlight"><pre><span></span><span class="n">df</span><span class="o">.</span><span class="n">plot</span><span class="p">(</span><span class="n">x</span><span class="o">=</span><span class="s2">&quot;x&quot;</span><span class="p">,</span> <span class="n">y</span><span class="o">=</span><span class="s2">&quot;y&quot;</span><span class="p">)</span><span class="o">.</span><span class="n">set_title</span><span class="p">(</span><span class="s2">&quot;My plot&quot;</span><span class="p">);</span>
</pre></div>
</div>
</div>
<div class="cell_output docutils container">
<img alt="_images/42d17247caaab5273a1efe99517b891a39da64b7ed8f206adf53ffb72326bde3.png" src="_images/42d17247caaab5273a1efe99517b891a39da64b7ed8f206adf53ffb72326bde3.png" />
</div>
</div>
<p>An output chart image is created directly from the data in the dataframe. The imag</p>

How/where is the image asset handled in the HTML generation process? Where would I need to look to make changes to provide a similar handler in the XML builder (perhaps extending the current custom XML build process to create my own XML builder?