Loop: beatloop_activate adopts rolling loop and quits slip mode

[ronso0]

While a rolling beatloop is active, press beatloop_activate to adopt this loop and quit slip mode.

This fixes #9445 for me.

• press and hold a looproll button for a transition, or just as filler
• notice I want to play with that loop, or simply need my looproll finger for other stuff, instead of holding the looproll button for the entire transition
• press beatloop_activate
  => loop becomes a regular loop, slip mode is deactivated (no seek!)
• release looproll button (nothin happens)
• do whatever I like with the loop

[github-actions]

This PR is marked as stale because it has been open 90 days with no activity.

[ronso0]

This works well, however fo convenience with mappings that don't have beatloop_activate but explicit loop controls (eg. beatloop_4_activate) we could add this functionality to the explicit loop controls, too.
Need to double-check what happens currently when activating a loop in a rolling loop though so we don't break any (valid) use cases.

edit
Explicit beatloops are unrelated. Currently they just change the beatlopp size but don't affect slip mode.
Will leave as is.

[acolombier]

I think this change makes sense - this is also a lacking aspect I have missed in the past. Does this need a manual update? Feels like it would be good to document it.

[ronso0]

Yup, we need to document it.
Will open a manual PR asap.

[ronso0]

Hmm, not sure how I tested back then and/or what changed since then, but this wasn't working as expected.

Now it works.

[ronso0]

Tested with keyboard mapping, controller test still pending.

The manual PR is mixxxdj/manual#766

[ronso0]

I almost went mad when I noticed that it works perfectly via GUI and keyboard but not with the Traktor Kontrol S4mk3 and my personal branch.

Then I realized that the S4 script does the same as #12475 🤦‍♂️

[acolombier]

Yeah, I had implemented this feature before it was a thing in the engine... I'll try a give this a go within the next few day but fee free to @ me if you haven't heard from my by the weekend!

[acolombier]

Tested and LGTM!