2002194 - `box-shadow` on hover with `transition` was awkward and jerky

Status: RESOLVED WORKSFORME

(Core :: Graphics: WebRender, defect)

Description

[Alice0775 White]

When I test Bug 2001865 on windows11.
At least in the former case of https://bugzilla.mozilla.org/attachment.cgi?id=9528795, I found one regression range where the shadow transition was awkward and jerky.
https://hg-edge.mozilla.org/integration/autoland/pushloghtml?fromchange=b0db2e4d0cf239551ffb7387931818807d7b567a&tochange=81380415b3584bb66b648ece8ce4a569ab7d95c5

At the very least, it appears that the following patch is one of the causes that made this issue more apparent.
a7c479e0c45eb836fdef21f2c44b5ef387dcd505 Glenn Watson — Bug 1898625 - Pt 4 - remove snapping from box-shadow rect after spread + offset applied r=gfx-reviewers,aosmond

Comment 1

[Alice0775 White]

Attachment: about:support

Comment 2

[BugBot [:suhaib / :marco]]

:gw, since you are the author of the regressor, bug 1898625, could you take a look? Also, could you set the severity field?

For more information, please visit BugBot documentation.

Comment 3

[Alice0775 White]

Attachment: screencast

Comment 4

[Daniel Holbert [:dholbert]]

I see this on Linux (Ubuntu 25.04) as well, FWIW.

During the animation, the bottom edge of the shadow should be monotonically moving downwards, but instead it jumps/flickers backwards at various points, as shown in Alice0775 White's screencast.

Comment 5

[Glenn Watson [:gw]]

This is somewhat expected, for now. As we go through and fix / improve various snapping related functionality it's likely to unmask other snapping bandaids that we'll need to fix as follow ups.

Comment 6

[BugBot [:suhaib / :marco]]

The severity field is not set for this bug.
:gw, could you have a look please?

For more information, please visit BugBot documentation.

Comment 7

[Glenn Watson [:gw]]

This seems fixed for me on current nightly?

Comment 8

[Alice0775 White]

(In reply to Glenn Watson [:gw] from comment #7)

This seems fixed for me on current nightly?

Yes, it is ok on Nightly155.0 Windows11.

Fixed range:
https://hg-edge.mozilla.org/integration/autoland/pushloghtml?fromchange=5936467e838ae7972407f13b861ecaf2425f6c52&tochange=7529226c22904bba38f5b08607e0d522d9e14d06

It appears that this issue has also been fixed in Bug 2026399.