xppen_{3,4}: init at {3.4.9-240607,4.0.7-250117}; nixos/xppen: init

[gepbird]

Summary

Add the official XP Pen tablet drivers:xppen_3, xppen_4 packages and xppen NixOS module.

Prior work

This PR is based on #285660, thanks for @nasrally's, the reviewers' and the testers' work!

Closes #285660, closes #347984.
Related: #213263, #277176

Testing

I belive this was sufficiently tested by @damiankorcz, many thanks!

I don't have any XP Pen tablets, the most I can do is check whether the GUI opens. If you own a tablet, please test whether this works for you, feel free to ask for help if you're unsure how to do it.

cc @damiankorcz and @misumisumi for testing the version 3 driver
cc @HangedFool for testing the version 4 driver

To test it, you can build your system with this PR and with this extra config and you should see the xppentablet desktop entry or PenTablet binary:

programs.xppen = {
  enable = true;
  package = pkgs.xppen_3; # or `pkgs.xppen_4` for the newer driver
};

Things done

• Built on platform(s)
  • x86_64-linux
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 24.11 Release Notes (or backporting 23.11 and 24.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

---

Add a 👍 reaction to pull requests you find important.

[damiankorcz]

Hi @gepbird,
Thanks for picking this up! I finally got some time to test this and overall I could use this fine. Everything I'd need works and can be setup. There are a few issues but for most use cases it should suffice. I tested with the xppen_3 package (will see if the xppen_4 picks up this tablet) and used your repository to temporarily replace my nixpkgs (I don't really know how to individually overlay just these packages over my usual setup).

Here is a general summary:

Working

• The tablet and pen are detected.
• Changing button functions on the pen (2 buttons).
• Changing button functions on the tablet (8 buttons).
• Battery status displays correctly.
• Changing the Pressure settings: Hardness and displaying the Current pressure.
• Mouse mode.
• Changing Pen Tablet mapping: Full area and Customize active area. Rotation also works.
• Does seem to retain configuration changes that were saved when fully restarting the app.
• Exporting config.
• Checked with Krita: Pressure settings, Disabling pressure, Disable tilt, Disable message and Disable Function Keys options in the XP Pen app impact Krita.
• Diagnostic tool shows info correctly:
  

Issues

1. Can't seem to move the XP Pen app window around. If i use Meta + Left Click drag I can move the window around.
2. Importing config doesn't seem to work correctly. I only get this in terminal when selecting the file:

"/var/lib/pentablet/conf/xppen/config.xml"
"PenTableLists"
"1.5"
"PenTableLists"
"1.5"

Here is the exported settings that I created with the app then tried to reimport after setting everything back to default: PenTablet_Config_2024-10-27.pcfg.pcfg.zip

3. The Identity option in the Work area tab doesn't seem to put the screen identifier on each individual screen. It's just bunched up on the screen that the XP Pen app is on.
   

4. The Rotation labels seem to disappear when the window is focused:

Unfocused	Focused

5. The Work Area section isn't displaying the monitor layout (you can see that in the 2 screenshots above) but when clicking on Customize screen area option it does show the layout correctly:
   

I can also see the following messages when interacting with the monitor options in this section:

qt.qpa.wayland: Wayland does not support QWindow::requestActivate()
QPixmap::scaled: Pixmap is a null pixmap

So I guess this might be a Wayland issue?

6. Probably not an issue but when I rebuilt my Nix config and tried to run the app right away the font was missing completely and in some places the characters were replaced with squares. After rebooting the system it was fine since.

Notes

• I'm using KDE 6.2.2, Wayland, Kernel 6.11.3, Nvidia RTX 2080.
• Tablet used for testing: XP Pen Deco LW (I used it wirelessly with the provided dongle for all tests).
• At least on KDE 6.2.2:
  • Settings' Drawing Tablet tab shows that the pen functions are Application-defined.
  • You need to set Map to screen: option to All screens. This is necessary for the XP Pen app's Work area section to map correctly to all your displays. This will let you select which display (or all) you want the tablet to map to in the XP Pen app. If this is set to something else in KDE settings it will map incorrectly since it limits the available area to the screen selected and I guess fits all the calculations within that area. Basically it's broken that way. I doubt this is a NixOS issues and just how it interacts with the KDE settings.

[damiankorcz]

Just rebuilt with the xppen_4 package and it doesn't detect the tablet wired or wireless. Assuming that it's not listed on the XP Pen Deco LW page (yet) then this is probably intended and not supported.

[ghost]

Hey! I wrote a commend encouraging you to pick my work up in my PR but got distracted and didn't send it :D So, thanks for picking it up! Glad my work was at least somewhat valuable, really hope you can get it through! :)

[gepbird]

Thanks for your detailed testing @damiankorcz!

I'm happy most of the features work for you.

1. Can't seem to move the XP Pen app window around. If i use Meta + Left Click drag I can move the window around.

Sad that the app disables default window decorations for their custom design. On a window manager like dwm there are no default decorations and I'm used to using keyboard shortcuts to move a window. However on the first "plug in your tablet" screen I can move the window without the keyboard, by starting to drag it on the top (eg. next to the close button). I think that should work on Plasma, can you check that? Otherwise I'm pretty sure it's an upstream bug.

2. Importing config doesn't seem to work correctly. I only get this in terminal when selecting the file:

"/var/lib/pentablet/conf/xppen/config.xml"
"PenTableLists"
"1.5"
"PenTableLists"
"1.5"

Here is the exported settings that I created with the app then tried to reimport after setting everything back to default: PenTablet_Config_2024-10-27.pcfg.pcfg.zip

I'll try to do some research on the data you sent, but I think an strace output would also help. To minimize the output of strace, please attach it right before you click on the export/import button, and detach it with Ctrl+C after you observe the issue.

sudo strace -p $(pidof PenTablet | cut -f2) -ff 2> xppen-strace

I'll help with addressing the other issues later, I'm just short on time.

[damiankorcz]

Hi @gepbird,
Here's a stack trace.

xppen-strace.zip

I've clicked on the Settings cog -> Export config -> Navigated to my desktop and saved the file. Then I again clicked on the Settings cog -> Import config -> Selected the file I just exported.

[gepbird]

@damiankorcz Sorry for the late response, I've been busy this week and hopefully have more time next week.

From the strace (system call trace) you sent, I see a lot of access to ~/.config/PenTabletrc file, it seems like the currently loaded configuration. Can you also send that? I'm curious whether it has the same format as the exported .pcfg file. If it does, then we can find out whether the issue is with the exporting or the importing part of a .pcfg file checking how much it differs to the PenTabletrc file.

Does seem to retain configuration changes that were saved when fully restarting the app.

If it saves the config between app restarts, then it must save the modified config in your home folder and not in the priviliged /var/lib/pentablet directory. From the strace, when you import the config, it reads the config then tries to delete /var/lib/pentablet/conf/xppen/config.xml which fails due to permission denied:

@damiankorcz can you test again if after restarting the app/machine, does the modified config get loaded, or it reverts back to the default? If it works, then I assume they messed up the import config code and only that tries to modify the installed config, in that case try running it as a superuser and check if importing works.

[gepbird]

The Identity option in the Work area tab doesn't seem to put the screen identifier on each individual screen. It's just bunched up on the screen that the XP Pen app is on.

Seems like a Wayland issue. I'm not familiar with that, but my guess it xppen is running inside an Xwayland session, so the application doesn't see all your monitors but only the area it takes up on the screen.

The Rotation labels seem to disappear when the window is focused:

Weird issue, I have no clue how something like that happens.

The Work Area section isn't displaying the monitor layout (you can see that in the 2 screenshots above) but when clicking on Customize screen area option it does show the layout correctly:

Looks like another Wayland issue.

qt.qpa.wayland: Wayland does not support QWindow::requestActivate()
QPixmap::scaled: Pixmap is a null pixmap

Interesting, I'll look into this later.

If anyone has some suggestions about these (presumably) Wayland issues, please comment it. And reproduction attempts of these issues on X11 could also help.

[damiankorcz]

Hi @gepbird,
Thank you for taking the time on this! Much appreciated.

Here's the PenTabletrc file:
PenTabletrc.zip

It seems that the file keeps a reference to the last imported (or exported?) file here so just to be sure it wasn't somehow loading from it I deleted them and when I restarted the app and system, the app seems to keep the settings saved correctly regardless.

As far as I can tell, it is successfully saving and loading the config file to /var/lib/pentablet/conf/xppen/config.xml. In case you want to look into there, here are the 3 files in that folder:
Archive.zip

1. config.xml - As far as I can tell is the current app config it loads as it starts up. These are mentioned when running PenTablet in the terminal:

Function  LoadConfig success

*a little lower down*

open file "/var/lib/pentablet/conf/xppen/config.xml

2. language.ini - Translation strings for different languages.
3. name_config.ini - List of PIDs for all supported devices / dongles.

---

When trying to run the app as sudo from the terminal I get the following and the app doesn't start:

[damian@nixos-desktop:~]$ sudo PenTablet
[sudo] password for damian: 
QStandardPaths: XDG_RUNTIME_DIR not set, defaulting to '/tmp/runtime-root'
QtLockedFile::lock(): file is not opened
QtLockedFile::lock(): file is not opened

---

Looks like the app is actually running under Wayland not Xwayland. I did a simple test with xeyes and ran xlsclients -l to confirm this.

When I have a chance I'll try getting X11 on my system and see how much of this can be replicated so we know if Wayland is to blame.

[gepbird]

As far as I can tell, it is successfully saving and loading the config file to /var/lib/pentablet/conf/xppen/config.xml.

You're right, your config differs from the default. At first I thought only root can edit this file then I checked its permissions:

~ ❯ stat /var/lib/pentablet/conf/xppen/config.xml 
  File: /var/lib/pentablet/conf/xppen/config.xml
  Size: 191313    	Blocks: 376        IO Block: 4096   regular file
Device: 0,30	Inode: 350807306   Links: 1
Access: (0666/-rw-rw-rw-)  Uid: (    0/    root)   Gid: (    0/    root)
...
~ ❯ stat /var/lib/pentablet/conf/xppen           
  File: /var/lib/pentablet/conf/xppen
  Size: 74        	Blocks: 0          IO Block: 4096   directory
Device: 0,30	Inode: 350807305   Links: 1
Access: (0755/drwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
...

From this, other people can write to the file (that's why the app modifying this config works), but can't delete it (that's why importing doesn't work, it tries to delete the old config and put there the new one):

~ ❯ echo foo >> /var/lib/pentablet/conf/xppen/config.xml
~ ❯ rm /var/lib/pentablet/conf/xppen/config.xml     
rm: cannot remove '/var/lib/pentablet/conf/xppen/config.xml': Permission denied

I've updated the PR to set the permissions correctly. I know 777 looks insecure, but our other options are putting these files in the user's home (this should be done in home-manager, not in nixpkgs) or creating a user for xppen which seems like unnecessary complexity.

@damiankorcz Please either

1. fix the permission manually with sudo chmod 777 /var/lib/pentablet/conf/xppen
2. remove /var/lib/pentablet, force pull the changes to this PR and rebuild your system

Then try importing a config and see if it works.

[damiankorcz]

Hi @gepbird,
I did the sudo chmod 777 /var/lib/pentablet/conf/xppen command and importing now works correctly. I tested by exporting my current config, reseting everything back to default, restarting the app and importing the file. I saved it and restarted the app again and it persisted.

[gepbird]

@damiankorcz I checked some documentation related to OpenGL and Wayland in nixpkgs and added some dependencies. Can you check if it fixes any of the previous issues, for example the "screen identifier" or the "rotation labels" issue? If it does, would you mind narrowing it down to the specific dependency(ies) that fixed it?

[damiankorcz]

Hi @gepbird,

I've checked and at least on Wayland it didn't seem to make a difference to any of those issues.

I've also just switched to X11 to test and it looks like:

1. The Screen identifier does go to each screen correctly.
2. In the Work area tab and Customize screen area option, the monitors are displayed correctly as you can see in this screenshot:
   
   So I can only assume something on Wayland is stopping the app from capturing the screen content.
3. The rotation labels still disappear when the window is focused so it might be worth checking if that is a bug with the app on other distros.

Everything else seems to work fine like it does on Wayland.

[damiankorcz]

Worth pointing out that the issues on Wayland are mostly visual in the app but the options still work correctly. Just slightly inconvenient when selecting which monitor you want the tablet to map to. But the dropdown lists all monitors correctly and it works. Same with the rotation indicators. You can just click off the app and see which one you want and select it. For both cases (for me with 4 screens) I just have to trial and error 4 options. You will likely do this once and be set. Perfectly serviceable if we can't find a solution.

[gepbird]

Thanks a lot for testing, so apart from a few minor visual issues, the v3 driver seems to work well.

I don't think we have people who have time to test the v4 driver, a previous iteration of it was tested and worked with a few issues that the NixOS module solves.

Other than the xppen_3 and xppen_4 derivations being almost the same with with many duplicated code, I think this is done. This is also done.

[gepbird]

Fixed merge conflicts.

@damiankorcz I really appreciate your testing feedback, but unfortunately I don't have the time, skills and tablets to debug and resolve it. I think most of the driver is usable without that and it's not a blocker. Anyone knowledgeable feel free to open a PR to my branch or later a follow-up :)

@PlushIrony thanks for the ping, I kinda forgot about this. As an alternative until it's not merged, you have a some options to use it:

1. (self plug) if you are using flakes, in my opinion the easiest is installing nixpkgs-patcher and adding this PR as a patch:

# file: flake.nix
{
  inputs.nixpkgs-patch-add-xppen = {
    url = "https://github.com/NixOS/nixpkgs/pull/351647.diff";
    flake = false;
  };
  # your other inputs like nixpkgs, nixpkgs-patcher
  # your nixos config output
}

# file: configuration.nix
{ pkgs, lib, ... }:

{
  programs.xppen = {
    enable = true;
    # by default you get the version 4 driver, if you want the version 3:
    # package = pkgs.xppen_3;
  };

  # your other configuration
}

2. if you are using channels (this is the default after a fresh NixOS installation), then I believe this should work:

# file: /etc/nixos/configuration.nix
{ pkgs, lib, ... }:

let
  nixpkgs-xppen = builtins.fetchTarball {
    url = "https://github.com/gepbird/nixpkgs/archive/xppen-init-v3-v4-nixos-module.tar.gz";
    sha256 = ""; # you will get an error message with wrong hash, insert that hash here
  };
  pkgs-xppen = import nixpkgs-xppen {
    system = "x86_64-linux";
    config.allowUnfree = true;
  };
in
{
  imports = [
    "${nixpkgs-xppen}/nixos/modules/programs/xppen.nix"
  ];

  programs.xppen = {
    enable = true;
    # by default you get the version 4 driver, if you want the version 3:
    # package = pkgs-xppen.xppen_3;
  };

  # your other configuration
}

[nixos-discourse]

This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/prs-ready-for-review/3032/5752

[PlushIrony]

@gepbird
I am having trouble implementing your second suggestion, I am importing the following file into my config but when I try to build I get error: xppen_4 cannot be found in pkgs

configuration.nix

{ config, ... }:

{
    imports = [
        # various modules
        ./modules/devices/xp-pen.nix
    ];
}

xp-pen.nix

{ pkgs, lib, ... }:

let
    nixpkgs-xppen = builtins.fetchTarball {
        url = "https://github.com/gepbird/nixpkgs/archive/xppen-init-v3-v4-nixos-module.tar.gz";
        sha256 = "sha256:021szj48piyvb3aj3qivh29zfg4f7xgpxhsa93sg5w47c54j10r7";
    };
    pkgs-xppen = import nixpkgs-xppen {
        system = "x86_64-linux";
        config.allowUnfree = true;
    };
in
{
    imports = [
        "${nixpkgs-xppen}/nixos/modules/programs/xppen.nix"
    ];

    programs.xppen.enable = true;
}

[gepbird]

@PlushIrony apologies, I only tested setting when I set the package, turns out it is necessary, try this:

{
  programs.xppen = {
    enable = true;
    package = pkgs-xppen.xppen_4;
  };
}

(The reason is, by default it tries pkgs.xppen_4 which doesn't exist on your nixos-25.05 or nixos-unstable branch, so we need to specify pkgs-xppen.xppen_4to use it from this PR)

[PlushIrony]

@gepbird
That worked to build however I am now having trouble launching the actual app. It says on the app proper that I need root permissions to run the driver.

This is what I get in the terminal

╰─ PenTablet 
QLocale::English
QObject::connect: Incompatible sender/receiver arguments
        QDesktopWidget::primaryScreenChanged() --> MainWindow::onDeskScreenChanged(int)
QPixmap::scaled: Pixmap is a null pixmap
Function  EnumDisplay nScreenCount: 2
Device.AllScreen "All monitor(-1920,0,3840,1200)"
Device.Screen 1 : "Monitor1(0,0,1920,1080)"
Device.Screen 2 : "Monitor2(-1920,0,1920,1200)"
QObject::connect: No such slot MainWindow::on_radioButton_m_touch_clicked()
QObject::connect:  (sender name:   'radioButton_m_touch')
QObject::connect:  (receiver name: 'MainWindow')
QObject::connect: No such slot MainWindow::on_radioButton_m_wheel_clicked()
QObject::connect:  (sender name:   'radioButton_m_wheel')
QObject::connect:  (receiver name: 'MainWindow')
-------type: 2
hid_open_path Failed!

[damiankorcz]

@PlushIrony
This might help: https://github.com/damiankorcz/nix-config/blob/main/common%2Fsoftware%2Fxppen.nix

It's how I had it setup. I'm no longer using NixOS so I can't test going forward.

[gepbird]

@PlushIrony interesting, IIRC that should be fixed by adding it as a udev package, which is already done. Maybe it only applies after a system restart? On last resort run it as root with sudo PenTablet

[PlushIrony]

@gepbird
The solution was restarting thanks so much for your help!

@damiankorcz
I don't think I need this given that @gepbird figured it out for me but I did want to thank you none the less for providing a resource to me and anyone who needs a reference.

Now that I have it working (nothing seems immediately off) I am going to head off for a bit. However tomorrow I will comprehensively test the driver and report any issues I find.

[PlushIrony]

I believe I have pretty comprehensively tested everything and so here are the issues I have found. I will include my opinion on how important of an issue this is and my (amateur) take on whether this problem is due to packaging, the upstream application itself, or any other external factors.

Tested on: NixOS Hyprland (wayland) - Artist Pro (Gen2) - driver version 4.07

• The pen pressure testing area does not show the actual pressure being drawn.
• This is inconvenient because it makes it harder to find exact pressure balance that works for you however it is ultimately minor because you can just test it in an art program like krita and adjust from there.
• I think this is an issue with the program itself (probably wayland) because I remember this exact problem being on the AUR package. TLDR: wayland bug

---

• Various bugs with mouse mode, work area, and calibration.
• This is mainly just annoying as it requires various configuration in the window manager to resolve but once done is fully resolved.
• This is almost certainly an issue with hyprland because the solution comes from configuring hyprland and futhermore these bugs were not exhibited on Plasma 6 (wayland). TLDR: hyprland bug

---

• Prompts appear with the same properties as a normal window would, this include stealing focus, not anchoring themselves, etc.
• This is not a big deal as you can just disable prompts or you can setup window-rules to make them function in a desired way.
• This (once again) is almost certainly an issue with hyprland as these bugs were not exhibited on Plasma 6 (wayland). TLDR: hyprland bug

---

• When the shortcut remote's wheel is set to rotate it can only rotate in one direction.
• Of the issue I have found this is probably the least notable issue but it is masquerading as the most notable issue. It appears to be a genuine inconvenience as you seemingly do not have full access to the ability to rotate but as it turns out it is just that the rotate keys are misbound by default. You can just rebind them to functioning keys by replacing the rotate input with a custom input that uses the correct inputs. (I hate that I used the word input three times in a span of ten words)
• I can't say for sure but I find it very hard to imagine that this issue is caused by anything other then something being incorrectly set in the program itself. TLDR: driver bug

All in all, pretty good. Very few problems and the ones I found were either easy to work around or caused by my specific setup (*cough* *cough*, hyprland). So, as far as I can tell with my setup, their are no issue with the v4 package.

[PlushIrony]

It is insane that this still hasn't been merged upstream; this pr was opened a year ago.

That being said, I just wanted to report that after about 2 or 3 months of using this I still haven't encountered any issues (minus the things unrelated to the package that I documented earlier)

[gepbird]

It is insane that this still hasn't been merged upstream; this pr was opened a year ago.

Yeah, unfortunately there are not many mergers, and new packages and especially new NixOS modules are slower to get merged, because it introduces maintainance burden and it requires a more extensive review. I'll try pining a few more people.

That being said, I just wanted to report that after about 2 or 3 months of using this I still haven't encountered any issues (minus the things unrelated to the package that I documented earlier)

I'm happy it works for you after a more extensive testing, and thanks for reporting it :)

[drupol]

Let's stop wasting time and move on. 1 year waiting for a PR to be merged is unrealistic. Thanks for your contribution, hope you're not demotivated to contribute again !