"Spin the carousel!" button, or similar

[towerofnix]

Brought up by Jebb (#hsmusic-chat) and this particular idea pitched and detailed by Lan (#hsmusic-chat).

Related to #500, but this is a distinct idea.

It would be fun to have a way to almost totally randomize an album carousel (on group gallery pages). That is, you click a button and some sort of animation plays to conceal the current album selection (could just be a fade to dark; could be rapidly spinning the carousel's contents; could be "curtains" sweeping over—regardless, make it fun, but avoid eye/motion strain). Then the veil lifts and you get a totally new selection of albums.

Some details:

• This is essentially a feature of carousels, but it mainly makes sense when the carousel is showing a selection of a gallery which is literally present on the same page. So, it fits group gallery pages, but not the homepage, for example.
• We don't want to needlessly conflate the HTML structure of the carousel. If possible, we should dynamically "copy out" the relevant contents of the gallery and use those to structure the replaced details in the carousel. The carousel only makes use of link targets and images, so this should be OK.
• Exclude albums that don't have any cover art, boo hoo.
• Otherwise, maybe some special dynamics, maybe not. We are representing Fandom and Beyond here, mainly, and since those groups' contents are huge and not generally "balanced" in any particular way, we may want to use reasonable heuristic limits, courtesy FF (#hsmusic-misc).
  • E.g, up to two singles, up to three solo albums, the rest are randomly selected from the remaining albums. (These are FF's numbers and we can totally play around with them.)
  • That data is not currently encoded onto the page. We'd ideally compute it from the gallery, i.e. with data tags data-album-kind="solo single" or such.