Last Comment Bug 780340 - Allow compositor-drive animation of visibility
: Allow compositor-drive animation of visibility
Product: Core
Classification: Components
Component: Layout (show other bugs)
: unspecified
: All All
: -- normal (vote)
: mozilla17
Assigned To: David Zbarsky (:dzbarsky)
Depends on:
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Reported: 2012-08-03 19:50 PDT by David Zbarsky (:dzbarsky)
Modified: 2012-08-30 13:31 PDT (History)
5 users (show)
See Also:
Crash Signature:
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Iteration: ---
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Has Regression Range: ---
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Patch (980 bytes, patch)
2012-08-03 19:52 PDT, David Zbarsky (:dzbarsky)
matt.woodrow: review+
Details | Diff | Review

Description David Zbarsky (:dzbarsky) 2012-08-03 19:50:51 PDT
Visibility does not actually affect the animation, since the element is always visible except for possibly the start and end states.  When the element is hidden, that is handled by layout.  This allows transitions like to be async.
Comment 1 David Zbarsky (:dzbarsky) 2012-08-03 19:52:18 PDT
Created attachment 648934 [details] [diff] [review]
Comment 2 Ed Morley [:emorley] 2012-08-04 10:14:38 PDT
Backed out as part of the mass tree revert due to bustage caused by other landings:

Once the tree is open again, this can reland :-)
Comment 3 David Zbarsky (:dzbarsky) 2012-08-05 10:04:15 PDT
Comment 4 Ryan VanderMeulen [:RyanVM] 2012-08-05 17:40:16 PDT
Comment 5 David Baron :dbaron: ⌚️UTC-7 (review requests must explain patch) 2012-08-05 17:57:07 PDT
What if it's a CSS animation involving keyframes, and the visibility state needs to change somewhere in the middle due to what's specified in the keyframes (or due to repetition from animation-iteration-count)?
Comment 6 David Zbarsky (:dzbarsky) 2012-08-05 18:52:15 PDT
Are you talking about something like
That doesn't work in Firefox currently.  In my testing, I could only get visibility to work for transitions, never for animations.

However, in theory since the animation is also sampled by the main thread, layout will set the frame invisible if it needs to, which will rebuild the layer tree.
Comment 7 David Zbarsky (:dzbarsky) 2012-08-05 19:35:00 PDT
So when I fix the 30%% thing, it does actually work as expected, even with async animations, because of what I said in my previous comment.
Comment 8 David Baron :dbaron: ⌚️UTC-7 (review requests must explain patch) 2012-08-05 19:55:49 PDT
Maybe that's because we're not doing anything to suppress the animation running normally in addition to running on the compositor thread?  But once we do, won't it be a problem?
Comment 9 David Zbarsky (:dzbarsky) 2012-08-05 19:59:46 PDT
That is correct.  At that point we can just sample the visibility on the compositor and set a scale(0,0) transform matrix on the layer if it should be invisible.  Or do you think we should do that now?
Comment 10 David Baron :dbaron: ⌚️UTC-7 (review requests must explain patch) 2012-08-30 13:31:58 PDT
This was backed out in bug 784239 (which is good, I think).

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