undercurl support #828

undercurl is an alternate form of underline, with curls.
it looks like this in notcurses-info output on kitty: example from kitty.
on foot:
example from foot
i'm also curious what (削除) bce (削除ここまで)(erase with background color, apparently) and kbd are, but that doesn't matter here (or at all?)

Right now, we don't plan on implementing undercurlies. To do so would require us to add 4 bytes (to hold the curly's color) to each cell, which would increase run-time memory usage with ~33%.

kbd refers to the Kitty keyboard extension, and support for it is being worked on. Latest master has the initial bits, and there are PR's open for the next pieces, with more to come.

kbd refers to the Kitty keyboard extension,

ah, thank you!

To do so would require us to add 4 bytes (to hold the curly's color) to each cell, which would increase run-time memory usage with ~33%.

that sounds pretty bad- didn't know it would be. thank you for the information! in that case, feel free to disregard this until in the future where a better solution might be thought of.

Correct me if I'm wrong, but in absolute terms the increased memory usage wouldn't be that much.

On my 4k screen in foot I get 96 rows and 424 columns. So (96 rows) * (424 columns) * (4 bytes/cell) = 162,816 bytes = 0.163 megabytes.

So if you have a hundred instances of foot open you'd be using an additional 16.3 megabytes. On modern hardware that amount is negligible, and I think most users would trade the ram for undercurl support.

I get that foot is trying to be minimal, so maybe this feature could be enabled behind an option? Similar to #57

On my 4k screen in foot I get 96 rows and 424 columns. So (96 rows) * (424 columns) * (4 bytes/cell) = 162,816 bytes = 0.163 megabytes.

That's just for the visible grid though. If you include the (default) 1000 lines of scrollback it'd be 10x that. 1.6MB is still relatively small in terms of memory usage, but there's also cache usage to consider.

I'm kind of in favor of undercurls, since it's the most obvious styling for spelling errors in editors, but it seems a bit optimistic to say it'd only use 0.163MB.

Any updates on this? I saw #1099 but it hasn't been merged yet.