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I would like to connect an external touchscreen to my laptop (Ubuntu 18.10, GNOME).

The touchscreen works fine when used as the only monitor (disabling Laptop screen). However, I would like to use the two monitors side-by-side.

What I already tried (and failed):

  • Rearrange monitors: Touch operations always go to the built-in monitor, independent of the monitor layout.
  • Setting WL_OUTPUT for the USB touch input in udev (as seen in that Tizen multi-monitor multi-touch documentation): It is being ignored (in fact, the weston source contains no reference to WL_OUTPUT; also, weston-info does not give any monitor names and I doubt the monitor names from xrandr are useful in this context).
  • Trying touchpad-edge-detector: Detects coordinates fine, but did not give any hints how to proceed.
  • Trying xinput_calibrator: Complains about illegal touch operations.
  • Using weston-touch-calibrator: Did not find it anywhere
  • I have not yet tried manually creating LIBINPUT_CALIBRATION_MATRIX, as I do not think this is the "good" way to do it (probably depends on monitor resolutions/arrangements/availability).

I think the Tizen approach would be best, i.e., to tell Weston which touchpad is related to which touchscreen. However, I cannot find a way to do this, including reading the libinput documentation and grepping through the weston source.

Having more than one monitor should not be so weird today anymore, should it? And having a touchscreen shouldn't be either?

Marcel Waldvogel
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  • It is not clear at all what is the behaviour you want. Have you tried this in Windows? – Nicolay77 Apr 22 '19 at 16:18
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    @Nicolay77 (a) I don't have any machines with Windows installed. (b) With multiple monitors in "join displays" mode, one of which is a touch screen, the touch events are mapped to a rectangle embedding both joint monitors. So, touching the middle of the touch screen will translate to an event in the middle of the combined (joint) display area, which is not under my finger. Please let me know if this makes it clearer. – Marcel Waldvogel Apr 23 '19 at 17:12
  • I don't think the issue has anything to do with Wayland in particular, as this fixed it for me: https://askubuntu.com/a/773812/140374 – Nicolay77 Apr 24 '19 at 21:05
  • I have a similar observation with gnome under wayland. When mirroring is used, it works well. If the external display is used as an independent monitor,touch events are sent to the internal laptop display, rather than to the external display, I confess I am using gnome 41 under fedora right now. – Tim Richardson Dec 16 '21 at 03:17
  • Marcel, I have been searching an answer for this question too, but no luck. Many people are using multiple touchscreens in their system, now they test on Ubuntu 20, and having a touch map to wrong video monitor. Why Wayland does not provide any solution for this? – Thai Nguyen Jul 21 '22 at 21:56
  • On X, it would just be a matter of using xinput --map-to-output and providing the screen and touchscreen devices. But on Wayland? Not sure how you'd do that. Adding a bounty as this is a good question that needs an answer. – ArrayBolt3 Jul 22 '22 at 06:21
  • Actually, not adding a bounty after all, since I think this is a lack of functionality, not a tricky problem. It might be worth a bug report on Launchpad.net. – ArrayBolt3 Jul 22 '22 at 06:34

1 Answers1

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Arch Linux Wiki documents this to be unsupported:

Wayland does not currently have a known method to lock touching to a specific display in any environment other than sway [...]

(Sway is a Wayland compositor for i3).

gaerfield
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