1189746 - When async pan/zoom is on, bay12games.com/dwarves/ background glitches during scrolling

Status: RESOLVED DUPLICATE of bug 1166301

(Core :: Panning and Zooming, defect)

Description

[Finn Bryant]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:42.0) Gecko/20100101 Firefox/42.0
Build ID: 20150731030206

Steps to reproduce:

1. Start up nightly with the new pan&zoom turned on
2. Load up http://www.bay12games.com/dwarves/
3. Scroll up and down quickly


Actual results:

Sections of the background image down the sides of the central blog posts will get "pulled along" by the scrolling, before hopping back into place. If you scroll fast enough, you can see across the top or bottom edge that there's a fixed copy of the background underneath.


Expected results:

With async pan&zoom turned off, the entire background image remains fixed throughout scrolling.

(also tested in new profile)

It is possible that this is intended behaviour, an acceptable cost fo the performance boost, but given the site in question is using a fixed background image with no obvious javascript/unusual magic that might make async scrolling especially difficult, it seems like this is something that compositing layers should be able to deal with.

Comment 1

[Finn Bryant]

I'll add that the "glitching" only occurs *during* scrolling, and disappears when the user stops scrolling.

Comment 2

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

Thanks for filing this. This is definitely something we intend to fix. It looks like the site is using a background-attachment:fixed on the body, which is covered by bug  1166301. Ordinarily I would just dupe this bug over but this looks like a slightly special cause where there's a single background getting painted into different layers and so only part of the background is jittering, rather than the whole background. It will likely still be fixed by bug 1166301 but I'll mark it as dependent for now in case there's additional things that need to be fixed after that one is done.

Comment 3

[Botond Ballo [:botond]]

The rendering looks good with the patches in bug 1166301 applied!