alpha precision

[ferllings]

Hello,

When I parse hex values with alpha #000000aa
I get { model: 'rgb', color: [ 0, 0, 0 ], valpha: 0.67 }
The same valpha value is calculated for #000000ab

This is probably due to the rounding when converting from 255 base to 1 base.
Is there a way to access the intermediate 255 base value?

I understand the difference isn't much between both values, but the problem is that I can't retrieve the original hex value from the object... both giving #000000aa

Any idea?

[Qix-]

I don't quite understand what you're asking - can you show some code with expected output and what you're really getting?

[ferllings]

Color("#000000aa") returns
{ model: 'rgb', color: [ 0, 0, 0 ], valpha: 0.67 }

Color("#000000ab") returns
{ model: 'rgb', color: [ 0, 0, 0 ], valpha: 0.67 }

So 2 hexa values produce the same object

And of course when I'm trying to reconstitute the alpha value using the object I get the same result for both. "aa" which is not correct for #000000ab

[Qix-]

Wow, this is definitely a bug. Thank you for reporting.

I'm actually surprised we support RGBA as the constructor - I don't remember that ever being the case (though it has been a while since I've worked on this module).

I originally thought this could have been a precision error in the node prompt but doing a comparison of the two values shows that it is indeed the same value:

Color("#000000ab").valpha == Color("#000000aa").valpha
> true

[Qix-]

Okay so digging deep into color-string's history, this was a bug that was introduced as a solution to another bug.

• Hex support wasn't added until Qix-/color-string#33
• A bug was uncaught there that rounded the alpha to either 0 or 1, which was "fixed" in Qix-/color-string@eb857c2
• However, the real fix should have been simply to remove the Math.round. Not sure what the rationale was to lock it to two digit precision (perhaps for aesthetic? which I'm over now). But there was no technical reason for it that I can find, and the other string parsers do not make the same guarantee.

I'll fix this in color-string and release shortly. Apologies for the delay, the pandemic made life a lot harder.

EDIT: npm has insanely aggressive caching now apparently, so the newly pushed color-string version isn't showing up yet. I'll update color when it finally does.

[Qix-]

Released as 3.1.3, thanks again for the report and apologies for how long it took to address.

[ferllings]

Thanks a lot.
And no worries, I know what it's like to work on opensource projects.