[Bug]: Stylus pressure is not usable

[TudbuT]

Problem description

Related: #315

It seems like pressure/tilt is not working for me, despite #315 being closed as completed, which is supposed to have pressure as per issue description. GIMP sees an input device with pressure + tilt, but does not receive any events from it -> I can't use it.

My device is a Samsung Galaxy Tab S8 Ultra running [uname -a] ˋLinux localhost 5.10.168-android12-9-27940245-abX900XXS6CXB4 #1 SMP PREEMPT Mon Feb 19 06:14:03 UTC 2024 aarch64 Androidˋ.

Screenshot of the input device picker:

I am running gimp in archlinux-arm (the gimp provided by termux doesn't even see the input device).

What steps will reproduce the bug?

1. Install a proot archlinux-arm on termux: https://github.com/TermuxArch/TermuxArch
2. Install xf86-input-libinput, xf86-input-evdev, and gimp
3. Open gimp
4. No pressure detection is present
5. Go to Edit > Input Devices
6. Find the one with Pressure and Tilt
7. Select screen mode on it (and no others) to make it the exclusive input device
8. No drawing is possible

What is the expected behavior?

I should be able to use the pressure sensitive stylus for drawing in GIMP.

[twaik]

Currently real stylus support is not implemented. Termux:X11 can send only transform Android stylus events to X11 mouse events.

[twaik]

It seems like I found something that can help us.

[twaik]

Are you using old version? I've got rid of absolute mouse 9 commits ago.

[night-nl]

Are you using old version? I've got rid of absolute mouse 9 commits ago.

Is that meaning stylus is working properly responsing to pressure?

[twaik]

No. That means I've got rid of absolute mouse 9 commits ago.

[twaik]

I can not reproduce it on termux's gimp on the latest artifact. Devices other than core pointer are not even enumerated.

[TudbuT]

Are you using old version? I've got rid of absolute mouse 9 commits ago.

Probably. I haven't updated in a bit - will do now.

[TudbuT]

New version is installed. Absolute mouse is gone as expected.

I can not reproduce it on termux's gimp on the latest artifact. As I mentioned in the issue description: I am running gimp in archlinux-arm (the gimp provided by termux doesn't even see the input device).

Your termux gimp looks exactly like mine. Only the proot distro's gimp sees the individual devices.

Here's a comparison of what i see on each now:

[TudbuT]

The proot distro still sees pressure and tilt present in the Lorie mouse, but as before they do nothing (except now I can actually use gimp with that mouse set to Screen mode, unlike with the old absolute mouse).

[twaik]

For some reason it recognizes relative horizontal and vertical high precision scrolling axes as pressure and tilt. I opened issue for termux's gimp so device enumerating should be fixed. I am planning to check what I can do with stylus recognition on Sunday.

[TudbuT]

Delightful, thank you!

[twaik]

Do you have a usb tablet which can be connected to PC, with working tilt and rotation axes?

[TudbuT]

Yes: I have weylus and also an old XP-Pen tablet lying around somewhere.

Edit: oh you mean tilt and rotation? not entirely sure. pressure and tilt are definitely supported, not sure about rotation on the XP-Pen tho.

[twaik]

AFAIK XP-pen does not support tilt and orientation. And I am not sure if Weylus reports orientation, at least I did not find this part in its code. Do you know how to check if x tilt, y tilt and orientation are configured right? Probably you know what instruments to use in Gimp? Or other ways?

[twaik]

@TudbuT @parkerlreed @Revess @Dr4kzor @ephetic @mistune Sorry for the ping, but it seems like all of you participated in discussions related to stylus. Do you have real wacom tablet with x tilt, y tilt and orientation working out of the box? Or maybe you know how to check if these axes are configured right? I am implementing the full stylus support but it is a bit hard to test it without knowing how it should behave and without testing on a real device (which I do not have). Thank you.

[Revess]

I do have a Wacom Tablet, the Wacom Intuos M Bluetooth Black. I dont know the full capabilities to test. For my tablet I have a samsung Galaxy Tab S8+ with the SPen. Feel free to let me know the pen capabilities. In the last update (last year summer I think) the pen support was working :)

[twaik]

Do you know how to test tilt and rotation capabilities in Gimp or other software? I need to test if I messed up with tilt formulas transforming tilt and rotation from Android to regular X11 format. So I need to know if tilt and rotation behaviour is the same in both cases.

[twaik]

In the last update (last year summer I think) the pen support was working :)

Currently termux-x11 supports only transforming android stylus events to X11 mouse events. Currently I am working on real stylus event forwarding, but I need someone who can test it.

[parkerlreed]

Still have it setup here if you need anything! Thanks.

I can do GIMP with pressure. Samsung doesn't do tilt, angle, or eraser.

[twaik]

I can do GIMP with pressure. Samsung doesn't do tilt, angle, or eraser.

It is pretty much weird because currently termux-x11 does not pass stylus pressure to the X server.

Do you know how we can check tilts and orientation? Maybe special Gimp instruments or similar stuff?

[twaik]

I do have a Wacom Tablet, the Wacom Intuos M Bluetooth Black.

Can you please post a screenshot of https://patrickhlauke.github.io/touch/tracker/multi-touch-tracker-pointer-hud-pep.html while holding stylus on a tablet? With all the properties it prints?

[Revess]

Do you want me to do the same thing with the spen and with the wacom pen on the tablet?

[twaik]

Currently only in chrome on pc with wacom tablet please.

[Revess]

Sure thing, later today or tomorrow (CET +1) I will try it with the link you provided on my Wacom Tablet!

[TudbuT]

I can do GIMP with pressure. Samsung doesn't do tilt, angle, or eraser.

It certainly does tilt. Angle I'm not so sure. Here the angle only works when its on the screen. Sketchbook always sees it.

[RalfWerner]

9 seconds stylus. The stylus touches the screen in second 5. The Samsung menu appears in floating mode and stylus pressure. Which I have done several times in touch mode. Helpful?

https://github.com/termux/termux-x11/assets/45426380/31c96a28-7402-4307-8b45-72b454e7caec

[twaik]

@parkerlreed @Revess @TudbuT Can you please test the https://github.com/termux/termux-x11/actions/runs/9365902745 ?

[twaik]

No, wait. We can not build it since gitlab.freedesktop.org is currently under maintenance and builder can not obtain source code.

[twaik]

I am not so sure when gitlab.freedesktop.org will be back so there is apk for tests. app-universal-debug.zip

[twaik]

@parkerlreed @Revess @TudbuT can you please test it?

[twaik]

Ok, https://github.com/termux/termux-x11/actions/runs/9365902745 is available too.

[TudbuT]

Checking it out now.

[TudbuT]

that seems to work perfectly!

[twaik]

Good. So I think I will fix the bug with device enumeration and after this it will be merged.

[TudbuT]

perfect! I'll show the device enumeration here:

in proot: (this is what i used, works for drawing perfectly.)

in termux directly (DOES NOT WORK FOR DRAWING):

[twaik]

Termux's gimp should be rebuilt, I opened issue in termux-packages repo.

[TudbuT]

Wonderful! That's probably it for this issue then.

I'll probably be opening another soon: The captured events transform does nothing at present when using samsung's official cover.

I might take a small look at the code first tho to see if I can spot anything (in which case I'll open a PR instead of an issue).

[twaik]

https://github.com/termux/termux-x11/pull/650 is merged so I am closing this. Termux's Gimp problem is not related to termux-x11 plugin and it is one more reason I am closing this.