Clamp RGB to sRGB gamut

[drwpow]

Changes

Fixes #9. Clamps colors to the RGB range.

Worth noting that this is the “bad” way to clamp; Björn Ottosen outlines keeping hue consistent and clamping lightness and chroma, which culori has implemented in their clampChroma(… 'oklch') method. I instead took the lazier approach of just clamping to (0, 1) as a first pass.

Culori’s clampRGB() function also takes the same lazy approach, but loads a bunch of converter methods for a total of 3.6 kB for what ends up being the same end result.

Alternative method

The alternate way of doing it the “right” way has a couple caveats:

• It adds ~ 3.8 kB of client weight. Which may not be much all things considered. Also worth noting that even though clampRGB() is a bit bloated, clampChroma() is not—it’s actually a complex calculation and does involve shifting a color through a couple color spaces to get the accuracy right.
• This only happens when the value changes externally (e.g. the slider), so you could argue that true gamut adjustment is outside the scope of this library. When colors are adjusted on the picker this problem doesn’t exist

But if the alternate method is preferred, it’s an easy swap

Reviewing

• See comments

[drwpow]

This seems a bit roundabout—converting to RGB just to clamp—but the problem isn’t really fixed otherwise. And I made it as performant as I could be by not clamping unless it’s actually needed (i.e. you can call clamp_color() for “free” on in-range colors)

[drwpow]

Alternate approach

Also, edited the PR notes, but if we wanted to do this the “correct” way, it’d just involve using Culori’s clampChroma(…, 'oklch') method here instead.

clampChroma() is the same method used on oklch.com for the “fallback” color which matches Björn’s implementation from my extensive testing.

So the tradeoff here is basically just is 3.8 kB of weight worth it to fix the problem? I could go either way, honestly

[drwpow]

Added a new /oklab page to test this out. Just a copy of the original RGB demo, just with the obvious colorspace change