Bug 354248

Summary:	Freehand annotation confuses tablet and touch events
Product:	[Applications] okular	Reporter:	Oliver Sander <oliver.sander>
Component:	general	Assignee:	Okular developers <okular-devel>
Status:	CONFIRMED ---
Severity:	normal	CC:	daniel-other+kdebug, flo.hennig, postix
Priority:	NOR
Version First Reported In:	0.23.60
Target Milestone:	---
Platform:	Other
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Oliver Sander 2015-10-23 12:06:32 UTC

I am using the freehand annotation tool on a Thinkpad Yoga, which comes with a touch screen and a stylus.  These are separate input devices, and Qt is able to distinguish between them.  I can draw with the stylus, but here is the problem:
1) Open the freehand annotation tool
2) Start drawing with the stylus
3) While still drawing, tap the screen with your finger somewhere else.
Result: At the moment of tapping, a spurious line appears (and stays!) which connects stylus and finger.
Unfortunately, this situation is not nearly as obscure as it sounds:  When writing with the stylus, you will frequently want to rest your palm on the screen.  The palm then acts like the finger tap, and you get lots of artefacts between palm and stylus tip.

Reproducible: Always

Comment 1 tuxflo 2019-04-17 17:56:13 UTC

Kind of sad that there is no comment or update in more then 3 years about such an huge improvement...

Comment 2 tuxflo 2019-04-17 17:57:54 UTC

Does someone know exactly why the mentioned patch from https://git.reviewboard.kde.org/r/125847/ has the state "Discarded"?

Would be really nice if Okular finally gets touch and gesture support...

Comment 3 Oliver Sander 2019-04-17 18:41:32 UTC

The patch you link to has been in Okular for a number of years.  IIRC its state is 'discarded' because it was moved to phabricator for the final review.

As for the trouble with freehand drawing: I have a half-finished patch that allows to disable mouse/touchscreen/stylus drawing separately, but I don't currently have time to finish it.