MFM: rendering of `fg` and `bg`

[Johann150]

Summary

In the rendering of $[fg ] and $[bg ], the default colors are #f00 for both. This means that if both functions are used on a piece of text, the text will have the same color as the background and will be unreadable. Maybe it would be better to have different default values for the two. For example, change the bg default color to #0f0.

Further, I think the color regex incorrectly matches 4 and 5 digit color codes: https://github.com/misskey-dev/misskey/blob/fb54c58a661bee64365b7ec0c52d456062aaa200/packages/frontend/src/components/global/MkMisskeyFlavoredMarkdown.ts#L208 Technically, 4 digit color codes do exist if you want to include the alpha channel, but then you should also accept 8 digit color codes. 5 digit color codes do not exist.

I suggest this alternative regex, which only matches 3 or 6 digit color codes: /^([0-9a-f]{3}){1,2}$/i

[futchitwo]

• related to #10683
• Transparent color codes may not be the intended specification, but in my opinion it would be better to be able to use 4 or 8 digit color codes as well since they are used by the community.

[Johann150]

Oh I didn't see that issue. I guess that can be handled there separately then. The only thing that remains here is changing the default color of bg then.

[EbiseLutica]

#xxx #xxxx #xxxxxx #xxxxxxxx に対応させるなら、 /^([0-9a-f]{3,4}){1,2}$/i かな

[Johann150]

That will also match 7 digit ones which do not exist because the 3,4 part can be different on repetitions. I think the shortest you can get is this: /^(([0-9a-f]{3}){1,2}|([0-9a-f]{4}){1,2})$/i

[acid-chicken]

/^([\da-f]{3}|([\da-f]{2}){2,4})$/i