Enabling multi-touch (pinch-to-zoom) in QtDragon HD with Touchscreen

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23 Feb 2026 22:01 #343371 by Ferra
Hello everyone,I hope this is not a trivial question — I am still learning the Linux input stack and QtVCP internals, so please excuse any misunderstanding on my side.I am running LinuxCNC with QtDragon HD (QtVCP) on Debian RT.
My touchscreen hardware supports 15-point multi-touch (confirmed on Windows).
On Linux, the device is detected as
wch.cn TouchScreen
.What I would like to achieve is:
  • Two-finger pinch for zoom in the 3D preview
  • Possibly two-finger rotation/pan gestures
​​​​​​​Any guidance, even high-level direction, would be greatly appreciated.​​​​​​​Thank you for your patience and for the excellent work on LinuxCNC.​​​​​​​​​​​

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24 Feb 2026 03:55 - 24 Feb 2026 04:05 #343376 by tommylight
Either way, it is a Linux thing to recognize multiple fingers if your monitor supports it, so might be better to look in the Debian forums.
Last edit: 24 Feb 2026 04:05 by tommylight.

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24 Feb 2026 06:01 #343381 by Hakan
The OS support for multitouch is there, or can be enabled.
What about qtdragon? Does it know how to handle multitouch events or geastures?

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24 Feb 2026 14:45 #343400 by cmorley
Qtvcp does not know about multitouch.
I don't have a multitouch to test with and QtPy5 had very little examples the last time I looked.

If you would like to try...
Somewhere around here is where you would add the code:
github.com/LinuxCNC/linuxcnc/blob/master...mlin/qt5_graphics.py

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24 Feb 2026 16:06 #343406 by tommylight
Does QtVCP zoom with mouse wheel?
Multitouch should at least emulate mouse buttons and wheel, but i never tried it... there is something for Linux enabling multitouch but i forgot the name, comes preinstalled with System 76 laptops and their Linux distro, see if you can find any info about it. I did test it on a touchscreen laptop quite a while back and pinch to zoom worked for most stuff, i do not recall testing LinuxCNC with it.

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