192f61bf0c
First, we used two caches. Turns out that lru_cache wasn't needed, the dict works perfectly fine on it's own. Second, we now also cache local images, so that we don't have to read them off the filesystem and convert them to base64 on every keystroke Maybe there should be a maximum size on that cache dict, but I doubt anyone would actually run into any trouble this cache taking too much ram.
139 lines
4.9 KiB
Python
139 lines
4.9 KiB
Python
""" Notice how this file is completely independent of sublime text
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I think it should be kept this way, just because it gives a bit more organisation,
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and makes it a lot easier to think about, and for anyone who would want to, test since
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markdown2html is just a pure function
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"""
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import os.path
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import concurrent.futures
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import urllib.request
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import base64
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import bs4
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from functools import partial
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from .lib.markdown2 import Markdown
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__all__ = ("markdown2html",)
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markdowner = Markdown(extras=["fenced-code-blocks"])
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# FIXME: how do I choose how many workers I want? Does thread pool reuse threads or
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# does it stupidly throw them out? (we could implement something of our own)
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executor = concurrent.futures.ThreadPoolExecutor(max_workers=5)
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images_cache = {}
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class LoadingError(Exception):
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pass
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def markdown2html(markdown, basepath, re_render, resources):
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""" converts the markdown to html, loads the images and puts in base64 for sublime
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to understand them correctly. That means that we are responsible for loading the
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images from the internet. Hence, we take in re_render, which is just a function we
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call when an image has finished loading to retrigger a render (see #90)
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"""
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html = markdowner.convert(markdown)
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soup = bs4.BeautifulSoup(html, "html.parser")
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for img_element in soup.find_all("img"):
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src = img_element["src"]
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# already in base64, or something of the like
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# FIXME: what other types are possible? Are they handled by ST? If not, could we
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# convert it into base64? is it worth the effort?
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if src.startswith("data:image/"):
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continue
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if src.startswith("http://") or src.startswith("https://"):
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path = src
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elif src.startswith("file://"):
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path = src[len("file://") :]
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else:
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# expanduser: ~ -> /home/math2001
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# realpath: simplify that paths so that we don't have duplicated caches
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path = os.path.realpath(os.path.expanduser(os.path.join(basepath, src)))
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try:
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base64 = get_base64_image(path, re_render)
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except FileNotFoundError as e:
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base64 = resources["base64_404_image"]
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except LoadingError:
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base64 = resources["base64_loading_image"]
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img_element["src"] = base64
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# remove comments, because they pollute the console with error messages
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for comment_element in soup.find_all(
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text=lambda text: isinstance(text, bs4.Comment)
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):
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comment_element.extract()
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# FIXME: how do tables look? should we use ascii tables?
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# pre aren't handled by ST3. The require manual adjustment
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for pre_element in soup.find_all("pre"):
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# select the first child, <code>
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code_element = next(pre_element.children)
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# FIXME: this method sucks, but can we do better?
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fixed_pre = (
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str(code_element)
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.replace(" ", '<i class="space">.</i>')
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.replace("\n", "<br />")
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)
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code_element.replace_with(bs4.BeautifulSoup(fixed_pre, "html.parser"))
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# FIXME: highlight the code using Sublime's syntax
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# FIXME: report that ST doesn't support <br/> but does work with <br />... WTF?
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return "<style>\n{}\n</style>\n\n{}".format(resources["stylesheet"], soup).replace(
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"<br/>", "<br />"
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)
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def get_base64_image(path, re_render):
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""" Gets the base64 for the image (local and remote images). re_render is a
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callback which is called when we finish loading an image from the internet
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to trigger an update of the preview (the image will then be loaded from the cache)
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"""
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def callback(path, future):
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# altering image_cache is "safe" to do because callback is called in the same
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# thread as add_done_callback:
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# > Added callables are called in the order that they were added and are always
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# > called in a thread belonging to the process that added them
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# > --- Python docs
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images_cache[path] = future.result()
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# we render, which means this function will be called again, but this time, we
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# will read from the cache
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re_render()
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if path in images_cache:
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return images_cache[path]
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if path.startswith("http://") or path.startswith("https://"):
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executor.submit(load_image, path).add_done_callback(partial(callback, path))
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raise LoadingError()
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with open(path, "rb") as fp:
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image = "data:image/png;base64," + base64.b64encode(fp.read()).decode("utf-8")
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images_cache[path] = image
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return image
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def load_image(url):
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with urllib.request.urlopen(url, timeout=60) as conn:
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content_type = conn.info().get_content_type()
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if "image" not in content_type:
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raise ValueError(
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"{!r} doesn't point to an image, but to a {!r}".format(
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url, content_type
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)
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)
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return "data:image/png;base64," + base64.b64encode(conn.read()).decode("utf-8")
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