Text on payun-payun parallax page disappears when it isn't fully in the viewport

RESOLVED FIXED in Firefox 64

Status

()

defect
P2
normal
RESOLVED FIXED
11 months ago
10 months ago

People

(Reporter: kats, Assigned: emilio)

Tracking

(Blocks 1 bug, {correctness, regression})

Other Branch
mozilla65
Unspecified
All
Points:
---
Dependency tree / graph
Bug Flags:
in-testsuite +

Firefox Tracking Flags

(firefox-esr60 unaffected, firefox63 unaffected, firefox64 fixed, firefox65 fixed)

Details

(Whiteboard: [gfx-noted][wptsync upstream])

Attachments

(4 attachments)

Go to https://belen-albeza.github.io/scroll-demos/parallax.html and start scrolling down. Observe the text-shadow on the "Payun-payun" header. As soon as the bounding box for that element hits the edge of the viewport the text shadow disappears.

I can reproduce on macOS and Windows. Happens even with APZ off.
Also related: the airplane that scrolls up from the bottom also disappears as soon as it encounters the edge of the viewport instead of getting clipped properly.
Keywords: correctness
OS: Unspecified → All
Priority: -- → P3
This sounds similar to the problem reported in this comment on github: https://github.com/servo/webrender/issues/3087#issuecomment-423595274

It seems that whenever 3d transformed elements are not visible in their entirety, we paint the wrong parts of the contents.
See Also: → 1492525
Priority: P3 → P2
(In reply to Kartikaya Gupta (email:kats@mozilla.com) from comment #1)
> Also related: the airplane that scrolls up from the bottom also disappears
> as soon as it encounters the edge of the viewport instead of getting clipped
> properly.

As of today, the airplane disappears, but some part of it is drawn in the tab-bar. 
Please see the screenshot attached
Posted image bug.png
see at the top of the tab-bar
The airplane looks fine now, it's only text what disappears.
AFAICS it's only text (shadows remain there correctly) and it's not only the header (other text like the "(Psttt… that browser is Firefox.)" also disappears.
Summary: Text shadow on header element payun-payun parallax page disappears when element isn't fully in the viewport → Text on payun-payun parallax page disappears when it isn't fully in the viewport
I'll take a look.
Assignee: nobody → emilio
Posted file Add a reftest.
Probably not the most reliable test to catch this (as it depends on
the font and such) but still fails here and I'd like WPT to have a test-case
for this. I'm looking into adding a WR test-case ATM, though fighting with
it way too much.
Posted file GitHub Pull Request
Still got to find a more reliable test-case for WR.
Backout by cbrindusan@mozilla.com:
https://hg.mozilla.org/integration/autoland/rev/3c25a0b6d269
Backed out changeset d44ae1668a70 as per emilio's request.
That is a linter bug, about:blank is a perfectly valid reference.
Flags: needinfo?(james)
Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/13487 for changes under testing/web-platform/tests
Whiteboard: [gfx-noted] → [gfx-noted][wptsync upstream]
Hmm, this was supposed to be fixed by https://github.com/web-platform-tests/wpt/pull/9421; I'll check what's going on.
Upstream PR was closed without merging
Whiteboard: [gfx-noted][wptsync upstream] → [gfx-noted][wptsync upstream error]
Whiteboard: [gfx-noted][wptsync upstream error] → [gfx-noted][wptsync upstream]
Whiteboard: [gfx-noted][wptsync upstream] → [gfx-noted][wptsync upstream error]
Whiteboard: [gfx-noted][wptsync upstream error] → [gfx-noted][wptsync upstream]
Upstream web-platform-tests status checks passed, PR will merge once commit reaches central.
https://hg.mozilla.org/mozilla-central/rev/2d5c8e9ca5a3
Status: NEW → RESOLVED
Closed: 10 months ago
Resolution: --- → FIXED
Target Milestone: --- → mozilla65
Upstream PR merged
Is this something we should consider backporting to Beta for the experiments running there or can this just ride the 65 train?
Flags: needinfo?(emilio)
Flags: in-testsuite+
Keywords: regression
I think the fix landed on beta, given https://github.com/servo/webrender/pull/3187 landed 20 days ago.
Flags: needinfo?(emilio)
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