1277712 - The URL bar hiding/unhiding causes the scroll position to jump around when directly viewing images

Status: RESOLVED WONTFIX

(Firefox for Android Graveyard :: Toolbar, defect, P3)

Description

[Jan Henning [:JanH]]

STR:1. Open some image directly within Firefox.2. Zoom in.3. Scroll up and down, so the URL bar hides/unhides.Actual:After the URL bar has become completely hidden/unhidden, the image makes a jump approximately the height of the URL bar in the opposite direction (i.e. if I'm scrolling towards the top of the picture, the viewport jumps back down and vice versa). The jump normally happens as soon as the URL bar has finished animating, although once it only occured after also lifting the finger.Expected :No jumping around.Note:Images are the most prominent example, but I can also reproduce this with the media controls that are displayed when directly opening e.g. an MP3 file. Normal web pages seem unaffected though.

Comment 1

[Jan Henning [:JanH]]

STR:
1. Open some image directly within Firefox.
2. Zoom in.
3. Scroll up and down, so the URL bar hides/unhides.

Actual:
After the URL bar has become completely hidden/unhidden, the image makes a jump approximately the height of the URL bar in the opposite direction (i.e. if I'm scrolling towards the top of the picture, the viewport jumps back down and vice versa). The jump normally happens as soon as the URL bar has finished animating, although once it only occured after also lifting the finger.

Expected:
No jumping around.

Note:
Images are the most prominent example, but I can also reproduce this with the media controls that are displayed when directly opening e.g. an MP3 file. Normal web pages seem unaffected though.
I can also reproduce this with and without APZ in all current Firefox versions.

Comment 2

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

Sample URL on which I can repro this.

Comment 3

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

FWIW I suspect this is because the toolbar show/hide resizes the height available to content, and the ImageDocument implementation probably uses that to position the image.

Comment 5

[BMO Automation]

Per policy at https://wiki.mozilla.org/Bug_Triage/Projects/Bug_Handling/Bug_Husbandry#Inactive_Bugs. If this bug is not an enhancement request or a bug not present in a supported release of Firefox, then it may be reopened.

Comment 8

[Oana Horvath [:ohorvath]]

The issue happens on this website too: https://www.mdr.de/mdr-klassik-radio/ipg/sendung805120_ipgctx-true_zc-4cd383ea.html. See Bug 1485540.

Comment 10

[jesbugduo]

Given this bug was reported 3 years ago, what's the ETA for a fix?

Comment 11

[Jan Henning [:JanH]]

No idea.

Comment 12

[Botond Ballo [:botond]]

(In reply to jesbugduo from comment #10)
> Given this bug was reported 3 years ago, what's the ETA for a fix?

I don't think we have a good way to fix this category of issues with the current implementation of toolbar hiding.

You can always work around it by disabling toolbar hiding in the settings (Settings -> General -> Full-screen browsing).

Firefox Focus has a different implementation of toolbar hiding which isn't susceptible to this problem, and that may replace the current implementation in Firefox for Android at some point, which would solve this problem. (Note that that implementation has other problems, like position:fixed elements attached to the bottom being partly or fully offscreen when the toolbar is shown. I don't think anyone has figured out how to implement a hiding toolbar without having bad interactions with _something_.)

Comment 13

[jesbugduo]

I tested the Dolphin browser, and it doesn't have this particular problem. So why shouldn't it be possible to fix the bug in Firefox?
I don't know how to fix the code myself, so I just hope everyone else affected can upvote this bug, so that someone can ultimately prioritize fixing the code.

Comment 14

[Botond Ballo [:botond]]

I guess it's possible that this particular issue could be fixed on the ImageDocument side. Would require some investigation.

It may not be worth spending time on that, though, if the toolbar hiding implementation is going to change anyways, to something that doesn't resize the height available to content.

Comment 15

[Jan Henning [:JanH]]

(In reply to Botond Ballo [:botond] from comment #14)
> I guess it's possible that this particular issue could be fixed on the
> ImageDocument side. Would require some investigation.

Given that normal HTML documents don't jump around, something should certainly be possible, especially given that for ImageDocuments (and I think also whatever standalone media files are using) we don't have to worry about possible side effects on position:fixed elements.

Comment 16

[Karl Dubost💡 :karlcow]

Could that be related to Bug 1514429 and Bug 1209426

Comment 18

[Botond Ballo [:botond]]

It was observed in bug 1544633 that this does not happen in Fenix.

Comment 19

[jesbugduo]

I see there is activity here.
Any news on the ETA?

Comment 20

[Randall Barker [:rbarker]]

(In reply to jesbugduo from comment #19)

I see there is activity here.
Any news on the ETA?

Not that I'm aware of.

Comment 21

[Botond Ballo [:botond]]

(In reply to Botond Ballo [:botond] from comment #18)

It was observed in bug 1544633 that this does not happen in Fenix.

As this issue is specific to Fennec, I don't think we're going to be fixing it.