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Comment by leeoniya | Hacker News Reader

i wrote something similar for this purpose, but much simpler and in 2kb, without AI, about a year ago.

uWrap.js: https://news.ycombinator.com/item?id=43583478. it did not reach 11k stars overnight, tho :D

for ASCII text, mine finishes in 80ms, while pretext takes 2200ms. i haven't yet checked pretext for accuracy (how closely it matches the browser), but will test tonight - i expect it will do well.

let's see how close pretext can get to 80ms (or better) without adopting the same tricks.

https://github.com/chenglou/pretext/issues/18

there are already significant perf improvement PRs open right now, including one done using autoresearch.

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Looks like uWrap only handles latin characters and doesn't deal with things like soft hyphens or emoji correction, plus uWrap only handles white-space: pre-line while Pretext doesn't handle pre-line but does handle both normal and pre-wrap.

correct, it was meant for estimating row height for virtualizing a 100k row table with a latin-ish LTR charset (no emoji handling, etc). its scope is much narrower. still, the difference in perf is significant, which i have found to be true in general of AI-generated geenfield code.

I've worked with text and in my experience all of these things (soft hyphens, emoji correction, non-latin languages, etc) are not exceptions you can easily incorporate later, but rather the rules that end up foundational parts of the codebase.

That is to say, I wouldn't be so quick to call a library that only handles latin characters comparable to one that handles all this breath of things, and I also wouldn't be so quick to blame the performance delta on the assumption of greenfield AI-generated code.

no disagreement. i never claimed uWrap did anything more than it does. it was not meant for typography/text-layout but for line count estimation. it never needed to be perfect, and i did not claim equivalence to pretext. however, for the use case of virtualization of data tables -- a use case pretext is also targeted at -- and in the common case of latin alphabets, right now pretext is significantly slower. i hope that it can become faster despite its much more thorough support for "rest of the owl".

uWrap demo has text extending beyond text boxes all other the place on Safari, is that the price of simplicity?

i don't have a mac to test this with currently, so hopefully it's not the price but a matter of adding a Safari-specific adjustement :)

internally it still uses the Canvas measureText() API, so there's nothing fundamentally that should differ unless Safari has broken measureText, which tbh, would not be out of character for that browser.

Chrome is no different, for example, "RobertDowneyjr" is out of the box, so does "enthusiastic" in a couple of places.

ack, see my reply to sibling comment: https://news.ycombinator.com/item?id=47572206

prepare uses measure text, if it is in a for loop, it won't be fast. This library is meant to do prepare once and then layout many times. layout calls should be sub-1 ms.

it is not clear from the API/docs how i would use prepare() once on one text and then use layout() for completely different text.

i think the intended purpose is that your text is maybe large but static and your layout just changes quickly. this is not the case for figuring out the height of 100k rows of different texts in a table, for example.

I think for that to use pretext is to join each row with hard line break and then do prepare once, then walk each line. At least that will put the single layout performance into the best light.

I am skeptical getting row height of many items only once is the intended behavior though. It is probably the intended behavior to get row height of many items and enables you to resizing width many time later (which is pretty useful on desktop).

tried just doing a concat of the 100k sentences with line breaks, it wasnt much faster, ~1880ms.

There's a handful of perf related PRs open already so maybe it will be faster soon. I'm sure with enough focus on it we could have a hyper optimized version in a few hours.

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