Scrolling by page causes flicker with smooth scrolling disabled
Categories
(Core :: Panning and Zooming, defect, P3)
Tracking
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People
(Reporter: kalle, Unassigned)
References
Details
When smooth scrolling is not enabled, scrolling via the Page Up/Down actions causes approximately half of the page to flicker.
Skipping a page down using the keyboard causes flicker in the bottom half, and skipping up causes flicker in the top half.
Interestingly, clicking on the scroll bar with the mouse causes flicker in the opposite half. The effect is also slightly less prominent.
The flicker always affects the content being scrolled, and it may or may not affect elements whose position remains fixed. On StackOverflow, for example, the fixed top bar does not flicker but the sticky navbar on the left does. On MDN, only the main content flickers; neither sidebar does.
Hardware acceleration is enabled.
Here are two screen recordings:
https://drive.google.com/uc?export=download&id=1-tXd6NMA-OBSkMOcXOweSJTGrrMAf5je
https://drive.google.com/uc?export=download&id=104cD0Oou2tj05A5Rt-1pT4dJBvuGhvJK
The first is from a subreddit that is particularly badly affected due to some custom style it has. The second is from Bugzilla's search demonstrating a more typical outcome.
I just tested this on Firefox v100 with a fresh profile, and the issue is present there, too. Unless something has changed in macOS, it's quite possible that the phenomenon has always existed and I only started paying attention now that I experienced a severe enough case.
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Comment 1•2 years ago
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Thanks for the report.
This looks very similar to bug 1783681.
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Comment 2•2 years ago
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The severity field is not set for this bug.
:botond, could you have a look please?
For more information, please visit BugBot documentation.
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Comment 3•2 years ago
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Yeah this is similar to bug 1783681. That's said;
(In reply to bintoro from comment #0)
When smooth scrolling is not enabled, scrolling via the Page Up/Down actions causes approximately half of the page to flicker.
Skipping a page down using the keyboard causes flicker in the bottom half, and skipping up causes flicker in the top half.
This isn't reverse checkerboarding, it's normal checkerboarding. And
Interestingly, clicking on the scroll bar with the mouse causes flicker in the opposite half. The effect is also slightly less prominent.
This is reverse checkerboarding.
Bug 1783681 should mitigate it.
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Comment 4•2 years ago
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bintoro, would you mind trying the latest nightly to see whether the flicker still is there? Thanks!
Sadly, I’m unable to see any difference between v120 (release channel) and the current Nightly.
However, I noticed a detail I neglected before. When starting from the top of the page, the very first page down action does not cause a flash; only subsequent jumps do. And it’s the same thing with the first page up action when starting from the bottom.
Only on my main profile (Dev Edition), I do get a small (~45 logical px in height) flash on the first page down at https://old.reddit.com/r/MacOS/, which is the badly affected page I mentioned in my initial report. I tried disabling some extensions but couldn’t get rid of it. On the test instances running relatively fresh profiles, I can’t discern even a slight flash.
Description
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