Bug 5760 - Scrolling in using a trackpad is too sensitive
Summary: Scrolling in using a trackpad is too sensitive
Alias: None
Product: ThinLinc
Classification: Unclassified
Component: Web Access (show other bugs)
Version: trunk
Hardware: All All
: P2 Normal
Target Milestone: 4.11.0
Assignee: Samuel Mannehed
Keywords: aleta_tester, nikle_tester, relnotes, upstream
Depends on: 7365
  Show dependency treegraph
Reported: 2015-12-18 15:42 CET by Samuel Mannehed
Modified: 2019-10-23 15:08 CEST (History)
4 users (show)

See Also:
Acceptance Criteria:


Description Samuel Mannehed cendio 2015-12-18 15:42:54 CET
We have had a report that scrolling is too sensitive in the HTML5 with a trackpad on Mac OS X. Scrolling with a normal mouse scrool-wheel also seems a bit too sensitive.

Could perhaps be related to Mac having a different resolution on the trackpad which we aren't handling properly.
Comment 2 Samuel Mannehed cendio 2015-12-22 16:11:23 CET
(In reply to comment #0)
> Scrolling with a normal mouse scrool-wheel also seems a bit too sensitive.

Disregard this, I have verified that this is not the case.

The issue with a trackpad remains unverified though. A trackpad from Apple will be ordered.
Comment 3 Samuel Mannehed cendio 2016-02-05 13:31:19 CET
I have reproduced the problem with the Apple Magic Trackpad using the HTML5 client running in Google Chrome and Safari on OSX 10.11.

Scrolling with the trackpad is extremely sensitive, it feels like maybe 10 times as sensitive in the HTML5 client compared to locally.

However, I can't reproduce the problem running the HTML5 client in Firefox on OSX 10.11.
Comment 4 Samuel Mannehed cendio 2016-02-05 13:39:45 CET
Upstream report:

Comment 5 Samuel Mannehed cendio 2016-11-29 13:51:49 CET
Also seems to happen on Chromebook
Comment 6 Samuel Mannehed cendio 2016-12-01 13:47:38 CET
(In reply to comment #5)
> Also seems to happen on Chromebook

Using the built-in touchpad that is.
Comment 7 Samuel Mannehed cendio 2017-09-12 15:47:07 CEST
Scrolling using the trackpad is way to sensitive on my laptop when running Windows as well. No problem in Linux on my laptop however.

This issue is not limited to Web Access. It stems from the nature of the RFB protocol where mouse wheel events are sent as clicks with a mouse up followed by a mouse down. The protocol does not have support for wheel delta or speed.

Currently both client implementations (TigerVNC's vncviewer and noVNC) send one mouse wheel event to the server for each wheel event no matter how small the wheel delta is. Trackpads seem to have a tendency for sending a lot of small delta events (delta ~= 0.01-1) while a regular mouse sends fewer larger delta events (delta ~= 4-60). VNC usage is only suitable for the latter case really.

One way to mitigate the problem with trackpads is to accumulate a number of small delta events in the client before sending an event to the server. A proposed patch that does just this for noVNC can be found here:

Comment 8 Pierre Ossman cendio 2019-10-08 11:03:00 CEST
Fixed in noVNC now. Will be resolved once we do a vendor drop.
Comment 9 Alex Tanskanen cendio 2019-10-22 16:55:27 CEST
This has now been implemented and works fine.

Works for MacOS when using trackpad on:
 ✓ Safari 13
 ✓ Chrome 77
 ✓ Firefox 69

Works fine on Linux laptop on:
 ✓ Firefox 69

Works on Windows 10 on:
 ✓ Edge 18
 ✓ Firefox 66

As for Chromebook, the scroll doesn't work on Firefox for Chromebook. See Bug 7405 for more information regarding this.
Comment 12 Niko Lehto cendio 2019-10-23 15:07:53 CEST
Verified that the problem existed on other platforms than just Windows 10 and macOS. Tested with apple magic trackpad on Fedora - Firefox 69.

So this issue is with high precision trackpads seemingly unrelated to OS, but the upstream fix solves this.

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