feat: convertColors plugin ignore currentColor in 'mask' elements

[salvan13]

convertColors plugin ignore currentColor in mask elements since it makes them not working properly

fixes #2031

[SethFalco]

Hey hey! Thanks for submitting a pull request!

Rather than adding the param, imo the plugin should just internally ignore masks for the convertColor option.

This was a use-case that was overlooked when the option was added, but I don't see a use-case to convert a mask to currentColor at all. (If that comes up in future, we can amend the convertColor option or introduce a new one to include masks.)

An issue with this solution is that it calls visitSkip, which stops all optimization. This would also stop it from applying any of the other options too, like converting white to #fff, which is valid for masks and shaves 1 byte.

A better way to approach it would be to declare a counter at the top that increments when an open mask tag is hit, and decrements when a close mask tag is hit, then only apply convertColor when that counter is 0. (We're not inside a mask.)

How does that sound to you? If you have any feedback or want guidance, feel free to ask!

[salvan13]

Hello! Thanks for your reply, it sounds good to me!

I also think that there is no use case for mask to convert colors to currentColor, I'll try to implement it as you suggested without a config and with a counter to not apply currentColor to mask, I'll update the PR asap!

[salvan13]

Hello @SethFalco I updated the PR, now it seems working great 😃
the mask colors are optimized but not changed to currentColor.
Thanks for your review!

[SethFalco]

Looks good to me! I've raised a minor issues with the types/defensive checks, but the logic is sound.

[SethFalco]

Awesome, thank you very much for the contribution!

This will be releases in v4.0.0-rc.1, and eventually v4.0.0.