Closed Bug 1336519 Opened 3 years ago Closed 3 years ago

[APZ] Wrong layerization (and missing content) with background-attachment:fixed

Categories

(Core :: Web Painting, defect)

defect
Not set

Tracking

()

VERIFIED FIXED
mozilla54
Tracking Status
firefox52 --- unaffected
firefox53 --- unaffected
firefox54 --- verified

People

(Reporter: mstange, Assigned: mstange)

References

(Depends on 1 open bug)

Details

(Keywords: regression)

Attachments

(2 files, 1 obsolete file)

Attached file testcase (obsolete) —
This is a regression from bug 1298218.

Steps to reproduce:
1. Load the testcase.
2. Scroll down until the blue bar is just offscreen.
3. Hover the scrollbar in order to trigger a main thread paint.
4. Scroll up.

The blue bar should become visible.

But it's not visible, because FrameLayerBuilder merged it into a layer below the fixed layer, because it thought the fixed layer was clipped by a scrolled clip the size of the viewport.
Assignee: nobody → mstange
Status: NEW → ASSIGNED
Comment on attachment 8833373 [details]
testcase

The bug doesn't happen with position:fixed.
Attachment #8833373 - Attachment is obsolete: true
Summary: [APZ] Wrong layerization (and missing content) with background-attachment:fixed / position:fixed → [APZ] Wrong layerization (and missing content) with background-attachment:fixed
Comment on attachment 8833380 [details]
Bug 1336519 - Don't try to detect scrolled clips using AGRs in non-APZ mode.

https://reviewboard.mozilla.org/r/109626/#review112200
Attachment #8833380 - Flags: review?(matt.woodrow) → review+
BTW, I believe I'm hitting this bug on the Mozilla phonebook (which has background-attachment:fixed on its <html> node).

STR:
 1. Visit https://phonebook.mozilla.org/?search/a (or probably any other long phonebook search-results page)
 2. Hit your "End" key.
 3. Scroll back up the page, with mousewheel scrolling or two-finger scrolling on trackpad (not arrow-keys or pageup).

ACTUAL RESULTS:
As you scrollback up, the top part of your viewport doesn't repaint right away as (particularly bits of newly-visible cards). It sometimes just stays blank indefinitely, until you force a repaint by switching windows/tabs/etc.

The regression range includes bug 1298218's changes, which is why I'm pretty sure it's this bug (a background-attachment:fixed regression from bug 1298218).
Pushed by mstange@themasta.com:
https://hg.mozilla.org/integration/autoland/rev/7796783a9de9
Don't try to detect scrolled clips using AGRs in non-APZ mode. r=mattwoodrow
https://hg.mozilla.org/mozilla-central/rev/7796783a9de9
Status: ASSIGNED → RESOLVED
Closed: 3 years ago
Resolution: --- → FIXED
Target Milestone: --- → mozilla54
Depends on: 1338579
Flags: qe-verify+
I reproduced this issue with both STR form comment 0 and comment 5, using an old Nightly build.

This is verified fixed on 54 beta 2 under Windows 10 x64.
Status: RESOLVED → VERIFIED
Flags: qe-verify+
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