1641142 - CSS animation causes drop-shadow to flashes

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, defect, P3)

Description

[nayinain]

Attachment: testcase.html

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0

Steps to reproduce:

1. Open the textcase.html

Actual results:

The heart halo is flashing.

Expected results:

The heart halo should not flash.

Comment 1

[nayinain]

Attachment: Capture 2020-05-27 00-16-15.webm

Regression window:

2020-05-27T14:17:03.511000: INFO : application_version: 76.0a1
2020-05-27T14:17:03.511000: INFO : platform_buildid: 20200326002916
2020-05-27T14:17:03.511000: INFO : platform_changeset: 3feaf53352b86d01b4d5b2dfb667d17e4fc4d8e8
2020-05-27T14:17:03.511000: INFO : platform_repository: https://hg.mozilla.org/integration/autoland
2020-05-27T14:17:03.511000: INFO : platform_version: 76.0a1
2020-05-27T14:17:14.173000: INFO : Narrowed integration regression window from [8d8c518d, bb1f05bf] (3 builds) to [8d8c518d, 3feaf533] (2 builds) (~1 steps left)
2020-05-27T14:17:14.181000: DEBUG : Starting merge handling...
2020-05-27T14:17:14.182000: DEBUG : Using url: https://hg.mozilla.org/integration/autoland/json-pushes?changeset=3feaf53352b86d01b4d5b2dfb667d17e4fc4d8e8&full=1
2020-05-27T14:17:15.590000: DEBUG : Found commit message:
Bug 1618000: Part 2: Clamp blur radius based on scale factors r=gfx-reviewers,nical

Differential Revision: https://phabricator.services.mozilla.com/D65805

2020-05-27T14:17:15.591000: DEBUG : Did not find a branch, checking all integration branches
2020-05-27T14:17:15.591000: INFO : The bisection is done.
2020-05-27T14:17:15.591000: INFO : Stopped

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1618000

Comment 3

[Lee Salzman [:lsalzman]]

Connor, can you take a look? Looks like there was some rounding added in the patch that is causing the jitter behavior?

Comment 4

[Connor Brewster [:cbrewster]]

Attachment: Bug 1641142: Fix rounding error when clamping blur radius

Comment 5

[Connor Brewster [:cbrewster]]

Yup, looks like this is due to rounding error introduced by clamp_blur_radius:
https://searchfox.org/mozilla-central/rev/bc3600def806859c31b2c7ac06e3d69271052a89/gfx/wr/webrender/src/picture.rs#411-422

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/0f1e35bee574
Fix rounding error when clamping blur radius r=gfx-reviewers,nical

Comment 7

[Raul Gurzau (:RaulG)]

https://hg.mozilla.org/mozilla-central/rev/0f1e35bee574