Bug 420770

Summary: okular-20.04.0: very sluggish scrolling behavior
Product: [Applications] okular Reporter: Till Schäfer <till2.schaefer>
Component: generalAssignee: Okular developers <okular-devel>
Status: RESOLVED FIXED    
Severity: normal    
Priority: NOR    
Version First Reported In: 20.04.0   
Target Milestone: ---   
Platform: Gentoo Packages   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: example of the scrolling behaviour

Description Till Schäfer 2020-04-29 21:18:33 UTC
Created attachment 128014 [details]
example of the scrolling behaviour

When scrolling fast with the mouse wheel through a document in okular 20.04.0 it is now a very sluggish experience. When using the scrollbar on the other hand everything is very fast. 

I have attached an example video. You can see the jumpiness of the scroll bar, when using the mouse wheel. Furthermore, the wheel scroll speed is almost identical through this video. When it comes to the bottom of the document it slows down a lot. In the second part of the video, I am using the scroll bar. As you can see, the scrolling is much smoother. 

I am using 
Okular 20.04.0
Frameworks 5.69.0
Plasma 5.18.4.1

.. on a not so slow pc (i7-4790K, with Geforce GTX 970 (nvidia drivers 440.82)
Comment 1 Till Schäfer 2020-04-29 21:19:48 UTC
maybe related to Bug 420755
Comment 2 Till Schäfer 2020-04-30 21:12:33 UTC
this is fixed for me by the following commit 


Git commit 08d368c13b0fa7368be9720b8de1b7a67188b8e9 by Nate Graham, on behalf of Kezi Olio.
Committed on 29/04/2020 at 22:15.
Pushed by ngraham into branch 'release/20.04'.

Fix scroll speed with free-spinning mouse wheels
FIXED-IN: 1.10.1

This just removes the smooth mouse wheel scrolling, fixing that problem.

M  +4    -10   ui/pageview.cpp

https://invent.kde.org/kde/okular/commit/08d368c13b0fa7368be9720b8de1b7a67188b8e9