Bug 396012

Summary: Relative mode inaccurate pen/cursor travel distance
Product: [Applications] systemsettings Reporter: Daniel <mayazcherquoi>
Component: kcm_wacomtabletAssignee: Valerii Malov <jazzvoid>
Status: CONFIRMED ---    
Severity: normal    
Priority: NOR    
Version First Reported In: unspecified   
Target Milestone: ---   
Platform: Arch Linux   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description Daniel 2018-06-30 09:03:44 UTC 
I really have no idea how to word this, but here goes.

I am using a Wacom Intuos Art Medium tablet, along with two monitors. I like to use relative mode, so the cursor doesn't jump all over the place across one or two monitors.

However, when using relative mode, the "bounds" of the tablet still seem to be derived from the screen(s). So the travel distance of the pen is still significantly larger than what it should be to allow for the user to move from one side of the tablet area to the other and in so doing will cause the cursor to traverse across one or both screens.

What I would ideally want, is for one centimetre of travel on the tablet, to also reflect one centimetre of travel on the screen, regardless of the size of the screen. This would allow for significantly more accurate drawing, without e.g. moving one centimetre along the horizontal causing the cursor to move quite a significant fraction (due to there being dual monitors) whereas moving along the vertical is much slower.

Sorry if that sounds confusing.

TL;DR: Moving the pen one centimetre in either the horizontal, vertical, or a combination of both directions, moves the cursor on the screen by that same amount.
Comment 1 Valerii Malov 2018-07-06 14:51:56 UTC 
Seems like slowing down cursor movements in relative mode can be achieved by doing one of two things:

* Setting "Device Accel Profile/Deceleration" properties
* Mapping to a much larger area than actual tablet area

Neither options are really currently supported by the KCM, but you can try setting them manually using xinput command. I'll probably add them in next version.

However specifically achieving 1:1 movement across multiple screens is non-trivial, if not impossible. As far as I understand this would require different movement speed for the cursor depending on the screen it is on, because different screens may have different DPI, and X11 probably does not support that.
Comment 2 Daniel 2018-07-17 08:14:46 UTC 
(In reply to Valeriy Malov from comment #1)
> Seems like slowing down cursor movements in relative mode can be achieved by
> doing one of two things:
> 
> * Setting "Device Accel Profile/Deceleration" properties
> * Mapping to a much larger area than actual tablet area
> 
> Neither options are really currently supported by the KCM, but you can try
> setting them manually using xinput command. I'll probably add them in next
> version.
> 
> However specifically achieving 1:1 movement across multiple screens is
> non-trivial, if not impossible. As far as I understand this would require
> different movement speed for the cursor depending on the screen it is on,
> because different screens may have different DPI, and X11 probably does not
> support that.

That's okay :-) If it can be locked to one screen (configurable) that's fine, because I never use the (Krita) drawing canvas across screens. I just need that 1:1 accuracy from tablet -> screen canvas (it would also be cool if there could be a fractional scaling modifier, too e.g. for a 0.9x or 1.1x scale to slow / speed up the cursor for precision drawing purposes).