1339925 - Text in scrollable frame is rendered outside the scrollable frame (not clipped properly) when displayport expires

Status: RESOLVED WORKSFORME

(Core :: Web Painting, defect, P3)

Description

[Kartikaya Gupta (email:[e-mail])]

Attachment: Screenshot

Latest Fennec Nightly on a Z3C with CM 12.1 (~Android 5.1.1). Load [1], scroll the attachment down to the bottom and wait 15 seconds for the displayport to expire. Expected: no visible change. Actual: text from the attachment is drawn outside the scrollable subframe. See attached screenshot.

[1] https://bugzilla.mozilla.org/attachment.cgi?id=8837566&action=edit

Comment 1

[Kartikaya Gupta (email:[e-mail])]

I don't see this in 52 beta or 53 aurora, so probably a recent regression. I'll mozregress it.

Comment 2

[Kartikaya Gupta (email:[e-mail])]

mozregression narrowed it down to this: https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=f985243bb630b2c78cd57731c8d8ab191aa09527&tochange=bf15d4078c2a6db7df37ab466d28a1e075c9eb4d

It was unable to find builds in taskcluster so couldn't bisect any further. However Markus' clipping patches are in that range and are a likely culprit.

Comment 3

[Milan Sreckovic [:milan] (needinfo for best results)]

Markus, is this something that looks like it'd fit in your 55 schedule?  Or, can you provide guidance for somebody else to fix it?

Comment 4

[Markus Stange [:mstange]]

Attachment: display list + layers dump

Stuff outside the iframe:
  asr(<0x85e7df10>)
  agr=0x85e7dca0
  clipChain()

Stuff inside the iframe:
  asr(<0x8e57fdc8>, <0x85e7df10>)
  agr=0x85e7dca0
  clipChain(<1290,12164,53608,24000> [0x85e7df10])

So in terms of asr, the contents are still layerized, but in terms of AGR they're not.
There's code in FrameLayerBuilder that is supposed to detect this discrepancy and apply any scroll clips that will not be set on the layer to the display items. It looks like that's not working properly here.

Comment 5

[Mike Taylor [:miketaylr]]

Unsure if we think this is important enough to fix for 57, or if it can wait.

Comment 6

[Ryan VanderMeulen [:RyanVM]]

Is this still reproducible for you?

Comment 7

[Kartikaya Gupta (email:[e-mail])]

Yes, still seeing this on current Nightly. Android 8.0, Sony Xperia XZ1 compact.

Comment 8

[Botond Ballo [:botond]]

This is fixed by the patch in bug 1486695.

Comment 9

[Botond Ballo [:botond]]

Unfortunately, the version of the patch in bug 1486695 that actually landed, does not fix this.

The previous version of the patch unintentionally tried to disable container scrolling for iframe RSFs; presumably it was that change that fixed this bug. However, that version was failing many tests. We do eventually want to disable container scrolling across the board, and that should fix this bug, but that's a larger change.

Comment 10

[Markus Stange [:mstange]]

This was probably fixed by WebRender.