1653773 - Zooming picture causes 95% scaling at 160%

Status: NEW

(Core :: Graphics: WebRender, defect, P3)

Description

[Wout B]

Attachment: Screencast from 07-18-2020 05:08:23 PM.webm

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0

Steps to reproduce:

I'm using Firefox 778.0.2-1 on Debian Unstable.

1. Open a 2560px wide PNG in Firefox on a 3840px wide monitor.
2. Zoom in (using Ctrl+scroll).

Actual results:

When I zoom in to 160%, the image gets scaled to 95% and thus isn't zoomed in further.

Expected results:

When I zoom in to 160%, the image scaling doesn't change, and thus I'm zoomed in further than with 150%.

Comment 1

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

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

Comment 2

[Jessie [:jbonisteel] pls NI]

Can you attach your about:support as a text file?

Comment 3

[Jessie [:jbonisteel] pls NI]

Rares, when you get a chance I'd be curious to see if this happens on Windows

Comment 4

[Wout B]

Attachment: about:support

Comment 5

[Darkspirit]

Can you upload Untitled.png to Bugzilla? Which desktop environment are you using?
Can you also check if latest Nightly is still affected?
$ sudo apt install python3-pip
$ pip3 install --upgrade mozregression
$ MOZ_ENABLE_WAYLAND=1 ~/.local/bin/mozregression --launch 2020-07-23 --pref gfx.webrender.all:true -a file:///home/woutjuh/Desktop/Untitled.png

or https://nightly.mozilla.org and start it with MOZ_ENABLE_WAYLAND=1 ./firefox

If it was fixed, could you try to find the fix range?
$ MOZ_ENABLE_WAYLAND=1 ~/.local/bin/mozregression --find-fix --bad 78 --good 2020-07-23 --pref gfx.webrender.all:true -a file:///home/woutjuh/Desktop/Untitled.png

Does it also reproduce with XWayland?
$ ~/.local/bin/mozregression --launch 2020-07-23 --pref gfx.webrender.all:true -a file:///home/woutjuh/Desktop/Untitled.png

If it's still reproducible, could you try to find the regression range?
$ ~/.local/bin/mozregression --good 76 --bad 78 --pref gfx.webrender.all:true -a file:///home/woutjuh/Desktop/Untitled.png

Comment 6

[Wout B]

Attachment: Untitled.png

This is Untitled.png, but like I said, it happens with any picture that is 2560 px wide.

I've tried it on both GNOME Shell and Sway, and it happens on both, as long as the Firefox window is 3840 px wide.

I'll try Nightly later.

Comment 7

[Rares Doghi, Desktop QA]

Hi, I was able to reproduce this issue on Windows as well with a 4k monitor but only if I would set the Scaling to 100% instead of the recommended 250%.
After setting the scaling to 100% on windows the issue occurs from 150% to 170% zoom level
When changing the scaling on windows to 125% on a 4k monitor the issue occurs at 120% to 133% zoom level