1392477 - Container bar animates smoothly, but tab loading spinner does not

Status: RESOLVED WORKSFORME

(Firefox :: General, enhancement)

Description

[:Atoll]

While looking for weird bugs in the UX, I noticed that the Container color bar animates smoothly in at my display's 60fps, but the loading spinner for tabs seems capped at a very low frame rate.

This eventually uncovered https://dxr.mozilla.org/mozilla-central/raw/browser/themes/shared/tabbrowser/pendingpaint.png which is a 12-frame APNG.

I wasn't sure how we made this APNG (there must be an SVG file somewhere, but I barely managed to get DXR to give me this result at all), but 12 frames probably isn't enough to make an animation as smooth as those we use in CSS directly above it.

Can we replace the loading spinner with something something acronym here other than APNG, so that it's smoothly animated like the rest of the tab bar UI?

Comment 1

[:Gijs (he/him)]

I'm slightly confused. The spinner you link to is the paint / process wait spinner, where we've switched to a tab and then that spinner displays right in the middle of the content area while we wait for the content process to render stuff.

But the summary talks about the "tab loading spinner", which I kind of assume is the spinner in the tab, pre bug 1352119. Which is this about?

Assuming this is actually about the spinner linked, Mike, is there a reason we're using a low-res-y thing here? Do we have a graphics stack available to do nice OMT paints at that point, or is that exactly what's busy getting us content data from the tab or whatever?

Comment 2

[:Atoll]

You're right, I linked the wrong spinner. I can't actually find what spinner we're using, sorry.

I'm definitely only talking about the spinner in the tab bar, but I guess I found a *second* spinner to ask the same question about!

Comment 3

[:Atoll]

Note that 60fps APNG is presumably spec-allowed, to offer a possible 'easy out' here; and, that the tab and content spinners are *apparently* different for reasons not yet defined.

Comment 4

[:Gijs (he/him)]

(In reply to Richard Soderberg  [:atoll] from comment #2)
> You're right, I linked the wrong spinner. I can't actually find what spinner
> we're using, sorry.

We switched in today's nightly (bug 1352119). Is it better in today's nightly?

Comment 5

[Mike Conley (:mconley) (:⚙️)]

ni?ing atoll for comment 4.

As for the tab switch spinner... yes, that's an APNG, and I suppose it might make sense to do something at 60 fps there... but ideally, we wouldn't show it at all, and I worry that rendering a high framerate animation while we're waiting for the content process to catch up might be counter productive, since that means we're spending more CPU cycles and thread time rendering the 60fps waiting animation rather than trying to clear whatever is blocking the main thread in the content process from proceeding.

Comment 6

[:Atoll]

The spinner seems improved in Nightly. As to the APNG spinner, no objections to leaving it alone. I was just in the wrong place.

Comment 7

[Mike Conley (:mconley) (:⚙️)]

Great, thanks!