trackscreen/README.md

trackscreen

Use a laptop touchscreen as a real multitouch touchpad. Toggle between modes with a five-finger tap.

• Touchscreen mode (the default): nothing changes. trackscreen only reads the touchscreen passively, so the desktop keeps native multitouch.
• Trackpad mode: trackscreen grabs the touchscreen and re-emits its touches through a virtual touchpad ("Trackscreen Virtual Touchpad"). libinput handles it like any other touchpad, so you get relative pointer motion with acceleration, tap-to-click (1/2/3 fingers = left/right/middle), tap-and-drag, two-finger scrolling, pinch zoom, and 3/4-finger swipes. Configure these in your desktop's normal touchpad settings (KDE: System Settings -> Touchpad).

The grab exists only in trackpad mode. The kernel releases it if trackscreen exits or crashes, so the touchscreen can't get stuck. A pen or stylus is a separate device and is never affected.

Requirements

Linux with libinput (Wayland or X11), Python 3 and python-evdev.

Install

./install.sh            # udev rule (sudo) + systemd user service, starts it now

The udev rule gives the logged-in user access to touchscreens and /dev/uinput. You can join the input group instead, but that also exposes every keyboard.

To run it by hand instead: ./trackscreen.py --debug

Toggling

• Five-finger tap: fingers down and up within 0.6 s, without moving. Tuning: --toggle-fingers N (0 disables it), --tap-time, --tap-move.
• trackscreen.py --toggle, or pkill -USR1 -f trackscreen.py. Bind either to a keyboard shortcut if you like.

A desktop notification shows the new mode (disable with --no-notify).

Other laptops / tuning

• --list-devices shows the auto-detected touchscreen; --device picks one by path or name.
• Physical size comes from the kernel or from udev (ID_INPUT_WIDTH_MM), so pointer speed is consistent across machines. Override with --size 307x187.
• If the built-in display is rotated, use --rotate 90|180|270. A LIBINPUT_CALIBRATION_MATRIX set in udev is applied automatically (--matrix overrides it).
• --speed 1.5 scales pointer and gesture speed on top of the desktop settings.
• --start-mode trackpad starts in trackpad mode.

Caveats

• In touchscreen mode the five-finger tap also reaches the desktop as five touches. It is usually harmless, but it can tap whatever is under your fingers.
• If "disable touchpad when a mouse is connected" is on, it also applies to the virtual touchpad.