Bug 449717 - When zooming with 2 fingers on a touchscreen, Okular also scrolls through the document, causing me to lose my place.
Summary: When zooming with 2 fingers on a touchscreen, Okular also scrolls through the...
Status: REPORTED
Alias: None
Product: okular
Classification: Applications
Component: general (show other bugs)
Version: 21.12.1
Platform: Arch Linux Linux
: NOR normal
Target Milestone: ---
Assignee: Okular developers
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2022-02-06 21:02 UTC by Ray Leon
Modified: 2023-03-02 17:17 UTC (History)
5 users (show)

See Also:
Latest Commit:
Version Fixed In:
Sentry Crash Report:


Attachments
Video of me zooming in and out on a digital copy of a textbook (3.72 MB, video/mp4)
2022-02-06 21:02 UTC, Ray Leon
Details
Video transcoded to .webm. Apologies, I skimmed the bug reporting guidelines a bit too fast. (1.74 MB, video/webm)
2022-02-06 21:24 UTC, Ray Leon
Details

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Description Ray Leon 2022-02-06 21:02:27 UTC
Created attachment 146357 [details]
Video of me zooming in and out on a digital copy of a textbook

SUMMARY
When zooming on a multi-page document with touchscreen gestures, Okular also scrolls through the document rather than staying in place.


STEPS TO REPRODUCE
1. Use a device with a Wacom touchscreen (I have a Lenovo Yoga c940)
2. Open a document with multiple pages in Okular.
3. Try to zoom using two fingers on the touchscreen.

OBSERVED RESULT
Other pages on the document zoom by. Zooming out increases the page number, while zooming in increases.

EXPECTED RESULT
The document stays on the same page, as it does when zooming with ctrl + / ctrl -

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux x86_64, with all packages up-to-date
(available in About System)
KDE Plasma Version: 5.23.5
KDE Frameworks Version: 5.90.0
Qt Version: 5.15.2
ADDITIONAL INFORMATION
Comment 1 Ray Leon 2022-02-06 21:24:34 UTC
Created attachment 146358 [details]
Video transcoded to .webm. Apologies, I skimmed the bug reporting guidelines a bit too fast.
Comment 2 Ray Leon 2022-03-20 17:32:21 UTC
This appears to only happen in browse mode (not when text selection or highlight are selected)
Comment 3 andreas.naumann 2022-04-01 19:05:31 UTC
In you videos, you show two pages side by side. Does it help, if you disable the "continous view" and show only one page? 
In that configuration, okular stays at the page and zooms only.

If I enable the view mode "overview", I get your behavior.  In that configuration, I would rather ask, what zoom in means to the developer.  
Looks to me, like okular increases the view starting from the upper left corner. 

It would feel more natural, if okular zooms into the area next to the finger position. Do we know the mouse position, when zooming?
Comment 4 Oliver Sander 2022-04-01 20:38:15 UTC
I reckon this is fixed by https://invent.kde.org/graphics/okular/-/merge_requests/134

Somebody would need to finish that.
Comment 5 Ray Leon 2022-09-29 21:04:45 UTC
(In reply to andreas.naumann from comment #3)
> In you videos, you show two pages side by side. Does it help, if you disable
> the "continous view" and show only one page? 
> In that configuration, okular stays at the page and zooms only.
> 
> If I enable the view mode "overview", I get your behavior.  In that
> configuration, I would rather ask, what zoom in means to the developer.  
> Looks to me, like okular increases the view starting from the upper left
> corner. 
> 
> It would feel more natural, if okular zooms into the area next to the finger
> position. Do we know the mouse position, when zooming?

Sorry for the late response. Disabling continuous view doesn't solve the problem, although I guess it makes it easier to manage since the view's only moving around on one page if that makes sense.
I also think you're right about the 'increasing view from the upper left corner' part.