1811574 - Smooth scroll not used for touchpad scroll on Wayland

Status: NEW

(Core :: Widget: Gtk, defect, P3)

Description

[Linus Kardell]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:108.0) Gecko/20100101 Firefox/108.0

Steps to reproduce:

1. Run Firefox on Wayland
2. Scroll very slowly with two finger scroll on the touchpad

Operating System: openSUSE Tumbleweed 20230113
KDE Plasma Version: 5.26.5
KDE Frameworks Version: 5.101.0
Qt Version: 5.15.8
Kernel Version: 6.1.4-1-default (64-bit)
Graphics Platform: Wayland
Processors: 8 × AMD Ryzen 7 3700U with Radeon Vega Mobile Gfx
Memory: 29.3 Gibyte of RAM
Graphics Processor: AMD Radeon Vega 10 Graphics
Manufacturer: Acer
Product Name: Aspire A315-41
System Version: V1.18

Actual results:

It snaps instantly between each scroll step. This is a regression from X11, where it animates the transition between each step. It's not very noticeable unless you scroll very slowly, since the steps are very small, but there is a definite difference.

Mouse wheel scroll, keyboard scroll and kinetic scroll is still smooth on Wayland, only direct touchpad scroll is affected.

Expected results:

Touchpad scroll is smooth.

Comment 1

[Linus Kardell]

Scrolling by dragging the scrollbar isn't smooth either, though that's not smooth on X11 either, so that's no regression.

Comment 2

[Negritas Sergiu, Desktop QA]

Hello! I have tried to reproduce the issue with firefox 111.0a1(2023-01-26) on Ubuntu 22.04 on Wayland, unfortunately I don't know if I have managed to reproduce the issue. Could you please answer the following questions in order to further investigate this issue.

1. Does this issue happen with a new profile? Here is a link on how to create one: https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles
2. Does this issue happen in the latest nightly? Here is a link from where you can download it: https://www.mozilla.org/en-US/firefox/channel/desktop/
3. Do you have any addons installed if so can you list them?
4. Could you please attach a video with the issue you are encountering?

Comment 3

[Linus Kardell]

Attachment: Firefox Wayland.mp4

Comment 4

[Linus Kardell]

Attachment: Firefox X11.mp4

Comment 5

[Linus Kardell]

Attachment: Nightly Wayland.mp4

Comment 6

[Linus Kardell]

Attachment: Nightly X11.mp4

Comment 7

[Linus Kardell]

I've attached videos of the different combinations, Firefox/Nightly on Wayland/X11. All with fresh profiles.

Comparing Firefox stable on X11 vs Wayland, you can see that on X11 it scrolls smoothly, while on Wayland in snaps between steps. Nightly on Wayland behaves the same as stable. Nightly on X11 behaves differently from the others though, it's still smooth like stable on X11, but it scrolls in much larger steps.

Comment 8

[Negritas Sergiu, Desktop QA]

Hello! Thank you for posting these videos. I have managed to reproduce the issue on Ubuntu 22.04 LTS with firefox 111.0a1(2023-02-09) I will mark this issue as NEW and set a component for it in order for our developers to look more into it and provide a solution to it.

If it's not the right component please feel free to change it to an appropriate one.

Comment 9

[Jan Alexander Steffens [:heftig]]

Does this improve if you disable apz.gtk.pangesture.enabled (in about:config)? Scrolling feels better here after disabling pan gestures.

Enabling msdPhysics also seems to have no effect when pan gestures are enabled. Apparently wheel events are transformed into scrolling quite differently with and without the gesture handling.

Comment 10

[Linus Kardell]

Yes, it's better with apz.gtk.pangesture.enabled=false