Bug 491490

Summary:	Threshold for horizontal touchpad scrolling in carousel view is too high
Product:	[Applications] Discover	Reporter:	Eamonn Rea <eamonnrea>
Component:	discover	Assignee:	Plasma Bugs List <plasma-bugs-null>
Status:	CONFIRMED ---
Severity:	minor	CC:	aleixpol, john.kde, nate, tamaskrall42
Priority:	NOR	Keywords:	usability
Version First Reported In:	6.1.4
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Eamonn Rea 2024-08-09 16:12:34 UTC

SUMMARY
On the Application Page in Discover, I cannot swipe horizontally to the next screenshot image using the trackpad without clicking. When clicking and dragging I can move to the next image no problem though. In fact with enough momentum I can scroll multiple. But when using a two finger drag on the touchpad it doesn't work.

With the two finger gesture the image will actually move with my fingers, and if I use enough precision I can even begin to see the next image in the carousel, but when letting go it does not swipe to the next image. I can scroll and see a bit of it at best but it never actually moves over and springs back to the current screenshot.

A similar bug is present for the review "Quotes" section beside the rating, although it is significantly harder to activate the scroll behaviour to begin with.

This may be a problem with the specific (QML?) component Discover is using, but I encountered this problem in Discover.

STEPS TO REPRODUCE
1. Open an Application Page in Discover (e.g. for Firefox)
2. Swipe horizontally on a trackpad
3. The screenshot will move but it will never swipe to the next image, it will just spring back.

OBSERVED RESULT
Cannot use a horizontal swipe gesture to move to the next screenshot image on an Application Page in Discover.

EXPECTED RESULT
I should be able to use a horizontal swipe gesture to move to the next screenshot image, just like when clicking and dragging.

SOFTWARE/OS VERSIONS
Operating System: EndeavourOS
KDE Plasma Version: 6.1.4
KDE Frameworks Version: 6.4.0
Qt Version: 6.7.2
Kernel Version: 6.10.3-arch1-2 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 7840HS w/ Radeon 780M Graphics
Memory: 30.7 GiB of RAM
Graphics Processor: AMD Radeon 780M

ADDITIONAL INFORMATION
Although I am on my laptop right now, I would assume this happens on my PC as well if I were to connect a touchpad to it.

Comment 1 Nate Graham 2024-08-12 19:16:35 UTC

I can get it to work, but the threshold is indeed quite high, yeah. We can probably lower it to make this easier.

Comment 2 Nate Graham 2024-08-12 20:28:39 UTC

So the culprit is these two lines on the relevant files:

snapMode: ListView.SnapToItem
highlightRangeMode: ListView.StrictlyEnforceRange

Because the items are so large, you need to perform a large horizontal scroll to avoid the view snapping back to the original item.

We want the items large, of course, because large screenshots are pretty and easier to view than small screenshots. I could be wrong but I don't see a lot of API for tweaking the behaviors here. We might have to override the touchpad scroll behavior.

Comment 3 Nate Graham 2025-05-19 18:05:11 UTC

*** Bug 504514 has been marked as a duplicate of this bug. ***