framebuffer text console and touch calibration

[fvolk]

[moved to own thread because it appears to be not display specific]

framebuffer console/minimal image:
Installing gpm gives touch reactions, but it is seemingly not calibrated, so quite useless.

The desktop (X+MATE) image:
Touch is calibrated and works in an xterm (or other terminal) as expected

I'm still stuck with this.
I want to get rid of X and the overhead of a desktop environment, just run a text console.

In pure framebuffer console - how to calibrate the touchscreen so that gpm's mouse events work properly?
How does X calibrate to a touch monitor?

[mctom]

Once I dived really deep into a touchscreen support back when I wanted to penguinize a Windows tablet - not much luck.
Xorg has a coordinate transformation matrix in its config files. There is an open source tool for calibrating touch screens (generating matrices), can't remember its name.
But that doesn't solve a problem for you anyway.

From my experience in no-X world, I would like to offer you an alternative of Cage + foot terminal.
https://github.com/cage-kiosk/cage
https://codeberg.org/dnkl/foot

Cage lets you run Wayland programs by creating a minimal session with a program of choice maximized in it. Once the underlying programs exits, so does cage.
It works very well for me on my technically still no-X machine. The overhead of Cage is minimal, and it's as easy to use as cage foot, or cage wesnoth.
And it's nice to have a full color terminal that supports any font at any size.

Here is some information about stuffing calibration matrix into Wayland:
https://wayland.freedesktop.org/libinpu ... n-via-udev
As far as I know, Weston has a built in calibration tool, weston-calibrator, that could produce a matrix for you.

I trust Wayland has touch screen support sorted out in a more elegant way than Xorg does - much like everything else in Wayland.
So far the only downside of Wayland is slow adoption and lack of recognition as a viable alternative. A familiar argumentum ad Windowsum

[fvolk]

Xorg has a coordinate transformation matrix in its config files. There is an open source tool for calibrating touch screens (generating matrices), can't remember its name.
But that doesn't solve a problem for you anyway.

Let me rephrase that:
I use C4 with VU7C and Ubuntu Mate and... it just works! No need for config.
I tried with other screens and various versions.

How does X accept the touch of the screen in correct position as mouse input and how to replicate this on the plain framebuffer console?

[odroid]

If your touchscreen is a capacitive type, you might not need a calibration process.

Try running 'evtest' on the text console to check basic functionality first.

[mctom]

Just to clarify, I don't claim that all touch screens require calibration on per-unit basis.
The calibration matrix is a general way of transforming one coordinates system into another, regardless of a reason to do so.
in case of gdm, it may even receive pixel-correct coordinates from the touch panel driver, but translate them into a position on a character map rather than pixel map.

Good luck getting this to work in fb.