Add animated loading indicator to explore and category pages

[FreddyFunk]

Adds simple loading indicator. Initial loading without any cached data can take a while on some systems so this gives the user at least some visual feedback that something is happening.

Please clear your cosmic-store cache before each test run to properly test. The cache can be cleared by running rm -rf ~/.cache/cosmic-store

[garrettjwilke]

loading the cosmic-store for the first time shows a Loading... with animated dots. clicking on "Updates" also shows a "Checking for Updates...` with animated dots.

the text shifts every time a new "dot animation" is added. it feels unpolished. it works, but if there is a way to make the string the full length of the animation regardless of how many dots are currently rendered would make it less abrasive.

[leviport]

Since this is a UI change, we should probably get UX's eyes on it. @garrettjwilke can you take a screen recording of the new animation and attach it here?

[garrettjwilke]

video capture of both the initial loading and the updates loading screens

cosmic-store.mp4

[FreddyFunk]

@garrettjwilke good point. I made the animation more stable/stationary now and the loading texts should no longer shift during animation.

[jackpot51]

This has a conflict in src/main.rs that needs to be resolved

[FreddyFunk]

rebased now

[maria-komarova]

I was about to comment about the words jumping because of the animation but it sounds like that was fixed. If someone could post the video with the fix I'd appreciate it.
I was wondering if the animation is a bit jittery but that could have been just the words.

[garrettjwilke]

updated animation video:

cosmic-store-fix.mp4

[maria-komarova]

Thanks @garrettjwilke, this helps.
I'd probably slow down the animation a bit to avoid having too much motion. It looks a little too fast and fragmented. We always strive to reduce motion. That should also make it look a bit more polished. It's a minor thing but since this animation is purely aesthetic we better get it right or not do it.
Also this will be replaced by the spinner once we have it so I don't know how much we want to change things now.

[maria-komarova]

It would also be great to add a delay before the word and animation appear to avoid the words flashing in case the page loads quickly. When I previously prototyped it I had 500ms delay.
For the animation duration we might try 1 second. Not sure what it is right now so difficult for me to gauge the exact timing but we might start with 1 second.

[FreddyFunk]

Also this will be replaced by the spinner once we have it so I don't know how much we want to change things now.

I think I will wait until a spinner is in libcosmic. Once it is, please ping me here, then I will update the pull request with the spinner and rebase it.

[defaultUser822]

Hello @FreddyFunk, sorry for the ping but I think that there is a spinner, it's the cosmic::widget::progress_bar::circular widget

Here's a short video of how it looks:

2026-04-14.13-11-46.mp4

Note: The video was recorded on GNOME, so that's why it might look different.