Source code for qtdraw.widget.mathjax
"""
MathJaxSVG converter.
This module provides mathjax to SVG converter.
"""
import re
import hashlib
from pathlib import Path
import asyncio
import threading
from playwright.async_api import async_playwright
import xml.etree.ElementTree as ET
from qtdraw.core.qtdraw_info import __top_dir__
from qtdraw.widget.color_palette import all_colors
# ===============================
# Global constants.
_MATHJAX_PATH = str(Path(__top_dir__) / "qtdraw" / "mathjax" / "es5" / "tex-svg-full.js")
_HTML_TEMPLATE = """
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<script>
window.MathJax={{
tex: {{ inlineMath: [['$','$'],['\\\\(','\\\\)']] }},
svg: {{ fontCache: 'none' }}
}};
</script>
<style>
body {{
margin: 0;
display: flex;
justify-content: center;
align-items: center;
font-size: 10pt;
}}
</style>
</head>
<body>
<div id="math">{latex}</div>
</body>
</html>
"""
# ===============================
[docs]
class MathJaxSVG:
_SVG_NS = "http://www.w3.org/2000/svg"
# ===============================
def __init__(self, cache_dir=None, clear_cache=False):
"""
MathJax converter.
Args:
cache_dir (str, optional): cache directory.
clear_cache (bool, optional): clear disk cache ?
"""
self._svg_cache = {} # memory cache.
# disk cache.
self._cache_dir = cache_dir or (Path.home() / ".qtdraw" / "svg_cache")
self._cache_dir.mkdir(parents=True, exist_ok=True)
# clear disk cache.
if clear_cache:
for f in self._cache_dir.glob("*.svg"):
try:
f.unlink()
except:
pass
ET.register_namespace("", self._SVG_NS)
# run event loop in independent thread.
self._thread = threading.Thread(target=self._thread_main, daemon=True)
self._thread.start()
# wait for execution of playwright.
self._ready = threading.Event()
self._ready.wait()
# =============================== event loop in thread.
def _thread_main(self):
self._loop = asyncio.new_event_loop()
asyncio.set_event_loop(self._loop)
self._loop.create_task(self._async_init())
self._loop.run_forever()
# ===============================
async def _async_init(self):
self._playwright = await async_playwright().start()
self._browser = await self._playwright.chromium.launch(headless=True)
self._ready.set() # complete execution.
# ===============================
[docs]
def convert(self, latex, color="black", size=10):
"""
Convert latex to SVG string.
Args:
latex (str): LaTeX code w/o $.
color (str, optional): color name.
size (int, optional): point.
Returns:
- (str) -- SVG string.
- (tuple) -- width and height.
"""
return asyncio.run_coroutine_threadsafe(self._convert_async(latex, color, size), self._loop).result()
# =============================== implementaion for convert with async for Jupyter.
async def _convert_async(self, latex, color, size):
if latex in self._svg_cache: # use memory cache.
svg_str = self._svg_cache[latex]
else:
cache_path = self._get_cache_path(latex) # use disk cache.
if cache_path.exists():
svg_str = cache_path.read_text()
else: # create SVG.
page = await self._browser.new_page()
html = _HTML_TEMPLATE.format(latex=latex)
await page.set_content(html)
await page.add_script_tag(path=_MATHJAX_PATH)
await asyncio.sleep(0.05)
svg_elem = await page.query_selector("mjx-container svg")
if not svg_elem:
await page.close()
raise RuntimeError("Failed to get SVG element.")
svg_str = await svg_elem.evaluate("el => el.outerHTML")
await page.close()
svg_str = self._flatten_svg_string(svg_str)
self._svg_cache[latex] = svg_str
# get scaled size.
x, y, w, h = map(float, self._get_attribute(svg_str, "viewBox").split())
scale = size / 1000.0
wh = int(w * scale + 0.99999), int(h * scale + 0.99999)
# set color.
svg_str = self._replace_attribute(svg_str, "fill", f"{all_colors[color][0]}")
return svg_str, wh
# ===============================
[docs]
def close(self):
# write memory cache to disk cache.
for latex, svg_str in self._svg_cache.items():
cache_path = self._get_cache_path(latex)
if not cache_path.exists():
cache_path.write_text(svg_str)
# close browser and playwright.
asyncio.run_coroutine_threadsafe(self._async_close(), self._loop).result()
self._loop.call_soon_threadsafe(self._loop.stop)
# ===============================
async def _async_close(self):
await self._browser.close()
await self._playwright.stop()
# ===============================
def _get_cache_path(self, latex):
hash_key = hashlib.sha256(f"{latex}".encode("utf-8")).hexdigest()
return self._cache_dir / f"{hash_key}.svg"
# ===============================
@staticmethod
def _get_attribute(svg_str, keyword):
match = re.search(rf'{re.escape(keyword)}="([^"]+)"', svg_str)
if match:
return match.group(1)
return None
# ===============================
@staticmethod
def _replace_attribute(svg_str, keyword, value):
if re.search(rf'{re.escape(keyword)}="[^"]+"', svg_str):
return re.sub(rf'{re.escape(keyword)}="[^"]+"', f'{keyword}="{value}"', svg_str)
else:
return svg_str
# ===============================
@staticmethod
def _flatten_svg_string(svg):
if not svg:
return ""
root = ET.fromstring(svg)
def unwrap_inner_svg(elem):
for child in list(elem):
if child.tag.endswith("svg"):
for grand in list(child):
elem.append(grand)
elem.remove(child)
else:
unwrap_inner_svg(child)
unwrap_inner_svg(root)
# unify all "fill" to currentColor.
for elem in root.iter():
if "fill" in elem.attrib and elem.attrib["fill"] != "none":
elem.attrib["fill"] = "currentColor"
return ET.tostring(root, encoding="unicode")
