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42 lines
1.5 KiB
Python
42 lines
1.5 KiB
Python
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import logging
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import os
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import subprocess
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from django.conf import settings
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from typing import Optional, Text
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from zerver.lib.str_utils import force_bytes
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def render_tex(tex, is_inline=True):
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# type: (Text, bool) -> Optional[Text]
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"""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 = os.path.join(settings.STATIC_ROOT, 'third/katex/cli.js')
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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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katex = subprocess.Popen(command,
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stdin=subprocess.PIPE,
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stdout=subprocess.PIPE,
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stderr=subprocess.PIPE)
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stdout = katex.communicate(input=force_bytes(tex))[0]
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if katex.returncode == 0:
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# stdout contains a newline at the end
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assert stdout is not None
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return stdout.decode('utf-8').strip()
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else:
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return None
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