945634 - Async zooming of fixed position, aligned content has regressed

Status: RESOLVED FIXED

(Core :: Panning and Zooming, defect)

Description

[Chris Lord [:cwiiis]]

It looks like the transform applied to fixed position content anchored to the bottom, right and/or top is applied twice now, as can be seen when zooming in at the given URL.

This seems to be a regression from either the fix in bug 941050 or bug 919144. Or maybe from some other bug (but I tested it prior to bug 919144 landing, and it was working then).

Let's track this, it makes async zooming of fixed content feel very weird/broken. I've only tested on Android, but this likely affects b2g and Metro too.

Comment 1

[Benjamin Kerensa [:bkerensa]]

roc, looks like some significant user impact regression. Can you look into this or assign someone to with possible backout?

Comment 2

[Robert O'Callahan (:roc) (email my personal email if necessary)]

I do not see this on my Nexus S on trunk.

I see what looks like a bug involving the vertical position of the pink div when I'm scrolling up. It's unrelated to zooming in. Everything else looks OK.

Did this get fixed by something else?

Comment 3

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Er, scrub that. I think I was testing the wrong build.

Comment 4

[Robert O'Callahan (:roc) (email my personal email if necessary)]

I think the problem is that anchor computation is busted.

Comment 5

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Attachment: fix

Comment 6

[Robert O'Callahan (:roc) (email my personal email if necessary)]

The anchor point is in the layer's coordinate system, whose 0,0 is the top-left of the fixed-pos frame.

Comment 7

[Robert O'Callahan (:roc) (email my personal email if necessary)]

https://hg.mozilla.org/integration/mozilla-inbound/rev/576dcc232795

Comment 8

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/576dcc232795

Comment 9

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Comment on attachment 8346320 [details] [diff] [review]
fix

[Approval Request Comment]
Bug caused by (feature/regressing bug #): 919144
User impact if declined: broken fixed-pos elements when zooming on mobile
Testing completed (on m-c, etc.): a little manual testing
Risk to taking this patch (and alternatives if risky): very low risk
String or IDL/UUID changes made by this patch: none

Comment 10

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-aurora/rev/e8523e7bddac