1899648 - When Fenix reopens, it briefly becomes transparent and flashes my Android home-screen / icon-grid at me

Status: NEW

(Firefox for Android :: General, defect)

Description

[Daniel Holbert [:dholbert]]

[I'm not entirely sure about the STR or reproducibility here. This seems to repro after Fenix has gone into some sort of "suspended" state after I've let ~5+ minutes go by without opening it]

Steps to reproduce

1. Open some web page in Firefox on Android.
2. Swipe up from the bottom of your screen to return to your home screen.
3. Allow 5-10min to pass (I'm not sure what the exact threshold is)
4. Tap the Firefox icon on your home screen to reopen it.

Expected behavior

Firefox reopens and shows me the page I was looking at.

Actual behavior

I get a weird flash of my homescreen as Firefox reopens. Specifically:

• Android rapidly animates a Firefox app-window growing to fill my screen. (This window is partially-transparent when it's quite small, but it's fully opaque for most of the animation.)
• Then, when the Firefox window fills my screen, it briefly becomes transparent so my home-screen shines through it, and then it becomes opaque again. [EDIT: sometimes this happens just before Firefox fills the screen; see comment 7 and screenshot in comment 8.]

Device information

• Firefox version: 128.0a1
• Android device model: Pixel 8
• Android OS version: 14

Any additional information?

I have "Smooth Display" enabled in Android system settings, which activates a high refresh-rate. I haven't tested without that setting yet, so I'm not sure if it's related to the bug or not; but it might help with making the bug noticeable, since the bad rendering is so brief.

Comment 1

[Daniel Holbert [:dholbert]]

Attachment: screencast of bug (ends a bit early perhaps; use the other one)

Comment 2

[Daniel Holbert [:dholbert]]

Attachment: screencast of bug

Comment 3

[Daniel Holbert [:dholbert]]

Attachment: slow motion presentation of attached screencast

Comment 4

[Daniel Holbert [:dholbert]]

The attached slow-motion presentation makes this a bit easier to see. Near the very end of the screencast, you can see Firefox switch from being fully opaque to suddenly be partially-transparent, with the bottom row of homescreen app icons showing through (and the Firefox/Nightly home-screen icons showing through at the top left corner).

Comment 5

[Daniel Holbert [:dholbert]]

Attachment: screenshot of the moment in the screencast where the bug is visible (see red boxes around homescreen icons that become visible, when Firefox becomes partially transparent

Comment 6

[Daniel Holbert [:dholbert]]

Attachment: screencast with red background and smooth display turned off (default)

I have "Smooth Display" enabled in Android system settings [...] I haven't tested without that setting yet

Update: I just reproduced the bug with Smooth Display deactivated, and it was actually much more noticeable in this instance. I used a red homescreen background color to be extra-sure that the homescreen was visible.

Walking through this video:

• As Firefox Nightly opens, the web page content is visible.
• BUT, Firefox's web-content area fades to be fully-transparent as we complete the app-open transition. So you just see your homescreen instead of the web page content.
• Then the homescreen icons & google bar disappear, but the red background is still there, filling our web content area.
• Then the web content area turns black.
• Then the web content area turns gray (same color as the dynamic toolbar)
• Then the actual web page content reappears.

Comment 7

[Daniel Holbert [:dholbert]]

Attachment: screencast of bug on Pixel 4 Android 13

Here's a screencast of the bug reproducing on a freshly reimaged Pixel 4 (with Android 13, essentially-untouched install of Nightly, and Smooth Display enabled in system settings.)

In this case, the Firefox web-content area turns transparent before it reaches a fully maximized size.

Also: just as noted in comment 6, Firefox's toolbar still seems to remain opaque; it's just the web content area that becomes transparent.

Comment 8

[Daniel Holbert [:dholbert]]

Attachment: screenshot of the moment in Pixel 4 screencast where the bug is visible (web content area briefly transparent, partway through transition)

Comment 9

[Daniel Holbert [:dholbert]]

So far I haven't been able to repro on Firefox release 126, FWIW (though I did reproduce the black/gray intermediate renderings from comment 6 once on release; I'm not sure if it hit the transparent rendering as well, because I didn't capture that one in screen recorder).

Comment 10

[Daniel Holbert [:dholbert]]

It looks like the flashes that I'm seeing here (transparent and/or black) on app-restore are the same as what jnicol described in bug 1772871. His "without patch" screencast shows the same transparent-flash that I'm focused on here at about t=2s (very briefly).

So: it seems this isn't a new issue, and it's really dependent on the change that jnicol suggests in bug 1772871.

--> Marking as a dependency of that bug (It might just be a dupe, ultimately fixed-by that bug, but it's probably worth keeping separate just in case there ends up being more that we need to fix this).

Comment 11

[Jeff Boek [:boek]]

Attachment: Screen_recording_20240529_165511.webm

Comment 12

[Jeff Boek [:boek]]

Let's try to reproduce this in GeckoView example to narrow it down between a Fenix and GV/Gecko bug

Comment 13

[Florian Quèze [:florian]]

(In reply to Daniel Holbert [:dholbert] from comment #0)

[I'm not entirely sure about the STR or reproducibility here. This seems to repro after Fenix has gone into some sort of "suspended" state after I've let ~5+ minutes go by without opening it]

On my Android device I sometimes see a black flash when switching back to Firefox. I think that was when the GPU process had been killed by the OS for excessive CPU or memory use, but the content process for the foreground tab was still alive (if the content process had been killed too, I would see an entire page load when switching back). You might be able to check if this is what is happening for you by checking if there's anything related in adb logcat. (I don't remember the exact message, but I guess grep for keywords like 'gpu', 'kill', ...)

Comment 14

[Jamie Nicol [:jnicol]]

adb shell ps | grep mozilla is handy for that

And in a debuggable app like gve you can adb shell run-as org.mozilla.geckoview_example killall org.mozilla.geckoview_example:gpu to test it

But that seems to match my recollection when I looked at this a couple years ago

Comment 15

[Jamie Nicol [:jnicol]]

(In reply to Jeff Boek [:boek] from comment #12)

Let's try to reproduce this in GeckoView example to narrow it down between a Fenix and GV/Gecko bug

It's definitely a gecko bug, but as I wrote in https://bugzilla.mozilla.org/show_bug.cgi?id=1772871#c1 the potential solution I discovered didn't work in Fenix, so it may need a fix on both sides

Comment 16

[BugBot [:suhaib / :marco/ :calixte]]

The severity field is not set for this bug.
:amejia, could you have a look please?

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