hsluv VS Scrawl-canvas

Here's a potential solution to having consistent accessible color palettes in Koala: https://www.hsluv.org

If you want to take a step further, take a look into perceptually uniform color spaces, like HSL(uv) or LCh(uv).

Maxima enabled me to make my color space [HSLuv](https://www.hsluv.org/). I encoded CIELUV <-> RGB transformation functions into Maxima, ran `solve` and converted the output back into code. It's great to be able to commit [Maxima code](https://github.com/hsluv/hsluv/tree/master/math) into your repository and not leave the math as an "exercise to the reader".

If you want to make it more useful than a browser's built-in color picker, perhaps support other color spaces? Maybe HSLuv or CIE L*a*b*?

Chroma could be included, but as a minor criterion. When I look at color pickers that try to balance human perception against geometric simplicity like HSLuv and Okhsl, chroma is the property that gets distorted the most. Perceptual brightness and hue seem to be more important.

> Now, HSL isn't necessarily the best color mode to use in every situation; it tends to produce gradients that can be overly bright and vivid, because it doesn't take into account human perception.

Shout-out to to [HSLUV](https://www.hsluv.org/) which does exactly that.

I'm a little bit of a color freak. Allow me to leave some suggestions :)

- Picking from the 256 color pallete will likely give you colors with different brightness. This may hurt readability of darker colors on a dark background, and may make some color stand out unintentionally. Consider using something like HSLuv [1] to pick colors with the same lightness, then convert to the closest Xterm color [2].

- To make it obvious there is a gradient, I'd pick one lightness (assuming HSLuv) and one saturation (I usually stick to 100%), then pick a distance in hue for each step. For example if I expect to see a maximum of 7 steps on the screen at once, one way is to start at 0, then 30, then 60, etc. You may choose to go over 180, but keep in mind 360 will be the same as 0 so maybe stop at 240. Note how by picking adjacent colors from the table you are still picking a distance, but the distance is too small so it's hard to see.

- You may want to choose a different starting point than 0, and maybe different direction for the steps, depending on whether you want the colors to "mean" anything. For example red is commonly associated with warning, so you can arrange to have the top of the range aligned with red. Or arrange to avoid the red region if you don't want that association.

[1] https://www.hsluv.org/

Check out HSLuv as an alternative for UI design: https://www.hsluv.org/

HSLuv is a HSL alternative, which aims to maintain the perceived lightness of colors across the hue spektrum. It also includes a HPLuv variant, which additionally maintains saturation, at the cost of color coverage. Both are very useful for procedually generating or modifying colors. More Info: https://www.hsluv.org/comparison/

> working with glyphs and iterating them in reverse for RTL is brain-breaking. And line wrapping gets really complicated. It's also the most obscure because nobody has written down everything you need to know in one place

I can confirm this. I've been working on a (much simpler!) text layout engine for my canvas library over the past couple of months and the amount of complexity associated with just stamping some glyphs onto a canvas has left me screaming at my laptop on an almost daily basis. Getting a decent underline was a proud moment!

Question: did you ever find out what algorithm the various browsers are using to calculate how many words can fit on a given line? I'm almost there, except words will occasionally jump between lines when I scale the text. Really annoying!

The PR's still a work in progress, but I've got all the functionality I want in there (shaping lines to fit in non-rectangular containers, styling text, text along a non-straight line, dynamic updates, etc). Just need to test and document it all now ... https://github.com/KaliedaRik/Scrawl-canvas/pull/75

I've got myself organised and prepared a List Of Things To Do[1] to make my 2D Javascript library even better than it already is. Given that I've been working on the library for over 10 years now, and have never before set out such a list, I call this Progress!

[1] https://github.com/KaliedaRik/Scrawl-canvas/discussions/cate...

'Kay, I don't know if this anywhere close to what the OP wants, but this sort of live browser tab manipulation is possible to do using a mix of a a canvas element and the browser's Screen Capture API[1] (plus my JS canvas library, once I merge and publish the changes into its next release[2]).

This solution[3] shows the modified browser tab in a separate browser tab. I've got no idea whether it's possible to do the same sort of trick in the same tab (but probably not). I also have no idea how secure the Screen Capture API is - I'd get very nervous about doing this sort of thing when looking at my bank's online portal!

[1] https://developer.mozilla.org/en-US/docs/Web/API/Screen_Capt...

[2] https://github.com/KaliedaRik/Scrawl-canvas/pull/57

[3] Youtube video of the effect: https://www.youtube.com/watch?v=hCi6LmKMAo0

My canvas library's README[1] has a video embedded in it. FWIW I'm not convinced it adds anything to the library's sales pitch.

[1] https://github.com/KaliedaRik/Scrawl-canvas

> And I’m just mentioning some of the unfixable problems with this approach

I agree that using a canvas instead of leveraging existing accessibility supplied by HTML/CSS/JS and the DOM is an accessibility nightmare.

However, I disagree that canvas accessibility issues are "unfixable". Difficult? Yes. But not unfixable. In my view, the element works best in partnership with its wider environment (HTML/CSS/JS and the DOM), not as a replacement for it. With that in mind, we can start to tackle the accessibility issues you raise - fonts, links, interactions, etc.[1][2]

I have an ambition to one day become intelligent enough to understand/code in Rust, and I'm really glad to see that people are thinking about accessibility as a fundamental part of UIs being developed in Rust.

[1] - Which is what my JS 2d canvas library tries to do: https://scrawl-v8.rikweb.org.uk/

[2] - My thoughts on accessibility, and how I try to fix them using my library: https://scrawl-v8.rikweb.org.uk/learn/eleventh-lesson/

If, however, your company is set on this course, I very strongly suggest you use a canvas library - if only for the MVP. Here's my canvas library (spam alert!) ... even if you don't use it in your product, the library might help give you some ideas on how to overcome some of the responsive, interactive and accessibility issues you'll be facing.

Scrawl-canvas - example and another example (links to code at bottom of each page)

My personal experience as a library developer, who has written my library in JS, not TS ...

TS is an excellent choice for a lib dev starting a new project today. I can see the advantages of using TS for the library code - in particular for a library that gets popular and welcomes contributions from other developers. However TS is a nightmare for someone like me who: 1. started writing the library 9 years ago; 2. has let the library get "quite" big; and 3. has only learned to use TS in the past year (for the day job) and is nowhere near to becoming a types expert.

I've had experience of people suggesting I rewrite the library in TS. Sometimes those suggestions have been quite 'evangelical' in their tone. As an (essentially) solo developer I just don't have the time, capacity or willingness to do that work - however much the end results might please others.

I also understand that having type definitions file for the library's interface is, nowadays, a critical factor if the lib dev wants others to use the library in their projects. But writing a .d.ts file for a large, mature repo to at least help those potential users can quickly turn into a World of Hurt. I know this because I've done that work[1] and I never want to do it again.

As much as I know that TS is a Force for Good in the JS coding world, there are days when I detest it!

[1] - link to the Scrawl-canvas .d.ts file on GitHub - https://github.com/KaliedaRik/Scrawl-canvas/blob/master/sour...