1516471 - Zoom location isn't restored after exiting fullscreen

Status: NEW

(Core :: Panning and Zooming, defect, P3)

Description

[csheany]

User Agent: Mozilla/5.0 (Android 7.1.1; Tablet; rv:66.0) Gecko/66.0 Firefox/66.0

Steps to reproduce:

 1. Open https://www.mozilla.org/en-US/firefox/
2. Zoom in on the right side
3. Enter fullscreen of a video 
4. Exit 


Actual results:

The page is zoomed in on the left


Expected results:

The page should still be zoomed in on right

Comment 1

[csheany]

Is this caused by Bug 1498812?

Comment 2

[Stefan Deiac]

Hi, thanks for your report. I can confirm this issue on all branches (Nightly 66.0a1 2018-12-26, Beta 65.0b5 and Release 64.0.1) using Samsung Galaxy Tab S3 (Android 8.0), Huawei P9 Lite (Android 6.0) and OnePlus 5T (Android 8.1.0). Also, I found that the scroll position is changed after exiting full-screen mode. This issue occurs on multiple sites not only on the link from the description.

Comment 3

[Botond Ballo [:botond]]

(In reply to csheany from comment #1)
> Is this caused by Bug 1498812?

Good question!

I believe that, unlike page navigation (bug 1509575), entering/exiting fullscreen mode does not involve the session store, and therefore, this is unrelated to bug 1498812.

Rather, this is a regression from bug 1493976. In that bug we changed the behaviour of entering/exiting fullscreen to zoom out when entering, and zoom back in when exiting. Zooming out and then back in can naturally lead to losing the visual scroll position (since the original scroll position may no longer be valid at the lower zoom level).

To fix this, we'll need to extend the approach taken in bug 1493976, to also save and restore the visual scroll position. As the relevant code runs on the main thread, restoring the visual scroll position depends on bug 1507279.

Comment 4

[Chris Peterson [:cpeterson]]

[geckoview:fenix:p3] because we should check whether this works in Fenix.

Comment 5

[Neha Kochar [:neha]]

Botond, is this something we can fix in 67?

Comment 6

[Botond Ballo [:botond]]

Given the other things I have in the queue for 67, I think 68 is more realistic. The regression seems to be fairly low impact, so I'd say shipping it in one more release is fine.

Comment 7

[csheany]

FWIW, since Bug 1423013 the page is technically zoomed in upon loading.

Comment 9

[Neha Kochar [:neha]]

Bulk change for all regression bugs with status-firefox67 as 'fix-optional' to be marked 'affected' for status-firefox68.

Comment 10

[csheany]

This is also a good test case

https://downloadfiletest-eab8a.firebaseapp.com/

Comment 11

[Liz Henry (:lizzard) (relman/hg->git project)]

Happy to take a patch for 70 but since this is triaged and set to P3 priority I'm setting it as fix-optional.
That will remove the bug from weekly regression triage.