Undo BPM Grid Change

[SephReed]

Feature Description

I've messed up a few bpm grids by clicking something I didn't mean to. There's no way to go back. Sometimes I can never get them back to where my cues line up with the lines.

[SephReed]

I've also deleted cues off the wrong track multiple times, or set cues on the wrong track, or set cues at the wrong time, or move knobs and not liking the change.

There's a lot of actions that can be done imperfectly.

[mxmilkiib]

This is kind of the same as #12774 I think, storing the state of BPM+beatgrid for undo purposes

[ronso0]

The question is which beat state should be stored:

• the state from the database when Mixxx is started (wouldn't cover newly loaded / unanalyzed tracks)
• the state when the track is loaded (wouldn't cover library actions on unloaded tracks)
• the last beat change? might be the beat shift, so any state before the last change that would be lost

[ronso0]

or set cues on the wrong track, or set cues at the wrong time

or move knobs and not liking the change.

Well, how exactly should Mixxx help with user 'errors'?

[mxmilkiib]

Regarding library actions made on a track without loading it; is that "loading" as in to a deck? I.e. not the "loading" of it into memory/an analysis algorithm?

The case of reanalysing an entire, say, 50GB (or very much likely more in some cases) library is something to ponder about how an undo mechanism might work in relation to. (Aside from the other issues you raise, Ronso.) I.e. a lot of memory use, or a lot of disk writes, or both in the case of paging/swap.

This is certainly not a non-trivial thing, as handy as it would be!

[SephReed]

For my purposes, the state that it was in 5 seconds ago before I clicked something and broke it.

I had a variable BPM track and tried to nudge the BPM a bit, which broke everything. I've also tried tapping a BPM only to find myself in a worse off position with no way back.

[ronso0]

I understand. I doubt such short fixed time would work, for example if you stretch the beatgrid, then skip through the track to verify it matches the visual beats.

IIUC a revert option could work if the Track object holds a backup, it's just the question when to create that.

[m0dB]

Ideally it should be a stack with undoable (and redoable) actions.

[ronso0]

I'll close this as fixed, now that #12954 has been merged.

I've also deleted cues off the wrong track multiple times, or set cues on the wrong track, or set cues at the wrong time, or move knobs and not liking the change.

I think this is covered by #13307