1210807 - Facebook page is incorrectly displayed when device is turned from portrait to landscape

Status: RESOLVED FIXED

(Firefox for Android Graveyard :: General, defect)

Description

[u549602]

Attachment: Screenshot_2015-10-02-15-51-26.png

Nightly 44.0a1
Device: Nexus 7(5.1.1), Sony Xperia Z2 (5.0.2)

Steps to reproduce
1.In portrait mode user taps on Awesomescreen
2.User enters Facebook and navigates to Fb "Log-in and Sign up" page
3.User flips device's orientation from portrait to lansdcape

Expected result:
The Facebook log-in page is correctly repainted in landscape mode 
Actual result:
The facebook page is incorrectly rendered in landscape mode 

Please note that this issue started reproducing with the 25th of August Nightly.
Also please note that before the 25th, on the Nightly builds the rendering was performed but with a minor delay
http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=8a6045d14d6bd348a3b5bfeb55a9321e680cc93e&tochange=04b8c412d9f58fb6194c58dcaa66bf278bbd53cf

Comment 1

[Michael Comella (:mcomella) [NI reported issues only: ex-Mozilla]]

Any ideas?

Comment 3

[James Willcox (:snorp) ([e-mail]) (he/him)]

Oops

Comment 4

[James Willcox (:snorp) ([e-mail]) (he/him)]

This looks like viewport-related badness, and Kats is in the pushlog there.

Comment 5

[Mark Finkle (:mfinkle) (use needinfo?)]

Assigning to snorp since kats is out for two weeks

Comment 6

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

Yeah looks like regression from my stuff. If this is still happening feel free to reassign to me.

Comment 7

[:Margaret Leibovic]

kats, it looks like this slipped through the cracks. Do you have time to look at this?

Comment 8

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

Hm, I don't have a device that can reproduce this. Does it still happen on Nightly or Aurora? (It might not happen on Nightly because APZ is enabled on Nightly, but if it affects current Aurora we should still fix it). I can put together a try push with extra logging once I know which channel to target.

Comment 9

[Kevin Brosnan [Ex-Mozilla]]

This only happens on aurora, beta and release. If you need a secondary testcase https://news.ycombinator.com with request desktop site or reddit.com homepage both reproduce this behavior.

Comment 10

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

Ah, thanks. I can repro using news.ycombinator on aurora. I'll look into it.

Comment 11

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

Attachment: WIP

So the problem here seems to be the order in which browser.js code gets invoked. On rotation, the MVM code runs and computes the correct resolution. That also triggers a reflow which runs the MozScrolledAreaChanged listener in browser.js, and that updates the displayport but using stale gScreenWidth/gScreenHeight values, and so it clobbers the resolution.

The attached patch is one possible fix, although I'm not sure what other side-effects it'll have.

Comment 12

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

I rebased and this patch doesn't fix it any more. Back to the drawing board.

Comment 13

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

I spent some more time banging my head against this and not getting anywhere. I'm inclined to just wait until APZ is shipping, since that seems to fix this.

Comment 15

[James Willcox (:snorp) ([e-mail]) (he/him)]

Actually moving this to 48 per comment #13

Comment 16

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

Seems to work fine in 48.