mirror of https://github.com/zulip/zulip.git
58 lines
2.1 KiB
Python
58 lines
2.1 KiB
Python
import logging
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import os
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import subprocess
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from typing import Optional
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import lxml.html
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from django.conf import settings
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from zerver.lib.storage import static_path
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def render_tex(tex: str, is_inline: bool = True) -> Optional[str]:
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r"""Render a TeX string into HTML using KaTeX
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Returns the HTML string, or None if there was some error in the TeX syntax
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Keyword arguments:
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tex -- Text string with the TeX to render
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Don't include delimiters ('$$', '\[ \]', etc.)
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is_inline -- Boolean setting that indicates whether the render should be
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inline (i.e. for embedding it in text) or not. The latter
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will show the content centered, and in the "expanded" form
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(default True)
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"""
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katex_path = (
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static_path("webpack-bundles/katex-cli.js")
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if settings.PRODUCTION
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else os.path.join(settings.DEPLOY_ROOT, "node_modules/katex/cli.js")
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)
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if not os.path.isfile(katex_path):
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logging.error("Cannot find KaTeX for latex rendering!")
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return None
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command = ["node", katex_path]
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if not is_inline:
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command.extend(["--display-mode"])
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try:
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stdout = subprocess.check_output(command, input=tex, stderr=subprocess.DEVNULL, text=True)
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# stdout contains a newline at the end
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return stdout.strip()
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except subprocess.CalledProcessError:
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return None
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def change_katex_to_raw_latex(fragment: lxml.html.HtmlElement) -> None:
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# Selecting the <span> elements with class 'katex'
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katex_spans = fragment.xpath("//span[@class='katex']")
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# Iterate through 'katex_spans' and replace with a new <span> having LaTeX text.
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for katex_span in katex_spans:
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latex_text = katex_span.xpath(".//annotation[@encoding='application/x-tex']")[0].text
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# We store 'tail' to insert them back as the replace operation removes it.
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tail = katex_span.tail
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latex_span = lxml.html.Element("span")
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latex_span.text = f"$${latex_text}$$"
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katex_span.getparent().replace(katex_span, latex_span)
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latex_span.tail = tail
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