Markdown highlighting is kinda slow

[suhr]

It should react instantly, but instead it takes about about 1-1.5 seconds to highlight something like *test*.

[pbek]

Thank you for the report, @suhr. The highlighting is done every second by a customized version of PEG Markdown Highlight. Do you think that is a problem?
I didn't want to highlight more than once a second because the possible load for huge files...

[suhr]

Do you think that is a problem?

Yes, editing doesn't feel smooth.

I didn't want to highlight more than once a second because the possible load for huge files...

You can parse markdown in a small window before parsing the whole file, for example.

[pbek]

You can parse markdown in a small window before parsing the whole file, for example.

Can you please explain in more detail what you are referring to. 😸

[suhr]

I'm not actually referring anything. Just a simple idea:

• Editing usually happens in a small area (even with multiple cursors), and parts of text with markup are usually quite short.
• Parsing small amounts of text is (or should be) quite cheap
• So we can have a small window around the cursor (for example, ~1024 bytes or even more) and parse&highlight text in it immediately on change
• You still have to parse the whole file, but you can do it less frequently

There're probably better ways to handle changing markdown (with something like incomplete syntax tree?), but I'm not aware of any.

[pbek]

That if the whole markdown file is one big code block (like I know some people are using it)?
And so far I only was able to parse the whole QTextDocument of the QTextEdit object with the highlighter. It has to set the styles directly in the document...
Do you have any suggestions for a better markdown highlighter for Qt QTextEditor that does everything we are currently doing. I wasn't aware of any so far.

[suhr]

Do you have any suggestions for a better markdown highlighter for Qt QTextEditor that does everything we are currently doing.

Um... Nope. I may know a bit about parsing, but I don't know Qt.

[pbek]

Currently the highlighting for the QTextEdit is done here: https://github.com/pbek/qmarkdowntextedit/blob/develop/highlighter.cpp in QMarkdownHighlighter::highlight().

[pbek]

Of course we can always make a setting that allows to set the ms time interval between highlighting commands, most systems would allow smaller intervals.

[pbek]

from the v16.06.3 changelog

• you can now set the markdown highlighting interval in the interface settings
  (for Issue #104)
  • if you set it to 0 the highlighting will be disabled
    (for Issue #197)

[pbek]

There now is a new release, could you please test it and report if the new features work for you?

[suhr]

It works. With a small highlighting interval it's much nicer to use, though it is still not instant like ghostwriter.

[pbek]

You are always welcome to write a faster one. 👍

[pbek]

@suhr @jd666

16.11.15

• a new markdown parser and highlighter was now implemented from
  the scratch to allow a higher parsing speed and more flexibility in
  the future
  • text will now be instantly highlighted, there is no
    highlighting-interval setting any more
  • now you also can change the styling in the settings or
    enable/disable the highlighting without re-starting the application
  • please report issues with the new highlighter if you find any
• markdown tables are now supported by the new markdown highlighter
  • the mono-space code font is used for it
  • you can change the highlighting color and other styles in the settings