Relax mod in osu!taiko is not implemented

[kawaemon]

Describe the bug:
If we pick Relax mod in osu!taiko, both of rim and centre key should hit all types of notes.
But it doesn't.

Screenshots or videos showing encountered issue:
https://streamable.com/e7s0a

osu!lazer version:
2020.215.0

[bdach]

It doesn't work because as far as I can tell, it currently is not implemented properly yet.

[quat1024]

I took a look at this, but I'm not sure where to start.

Afaik these are the things taiko Relax does in stable:

• If there's a tap note with an active hit window (including the early-miss window), the drum input is corrected to the color of the tap note.
  • The corrected input is shown on the left-side drum icon and the sound for the corrected input plays. I'm not sure whether the replay saves the real or corrected input...
  • The corrected input is on the same side of the drum; left rim gets corrected to left center. You can't get the bonus on a strong note by hitting both keys on the same side of the drum.
  • The second input on a strong note has to be within the 30ms window to be eligible for correction, I think?
• You don't have to time drum rolls very well, it's easy to complete them by mashing.
  • Wiki says that it gives "more lenient timing" but isn't specific on the details.
• Swells can be hit with any color sequence.

Some possible implementation paths:

• Littering the taiko drawable hit processing code with "is relax turned on" checks woooo
• Carefully placed magic booleans, like TaikoModClassic
• Swapping out the implementation of hit objects, kinda like OsuModStrictTracking
• Using IKeyBindHandlers, like InputBlockingMod. I messed with this and you can use it to cancel inputs, but I don't think you can correct inputs with them, especially not in a way that will fool the taiko game but not the key overlay or replay file

[smoogipoo]

Using IKeyBindHandlers, like InputBlockingMod.

Sounds like you want a combination of both InputBlockingMod and OsuModRelax. I.e. block the input and propagate the correct one.