Weylus turns your tablet or smart phone into a graphic tablet/touch screen for your computer!

Weylus in action with Xournal++:

• Control your mouse with your tablet
• Mirror your screen to your tablet

The above features are available on all Operating Systems but Weylus works best on Linux. Additional features on Linux are:

• Support for a stylus/pen (supports pressure and tilt)
• Multi-touch: Try it with software that supports multi-touch, like Krita, and see for yourself!
• Capturing specific windows and only drawing to them
• Faster screen mirroring

Just grab the latest release for your OS from the releases page and install it on your computer. No apps except a modern browser are required on your tablet.

Start Weylus, preferably set a password in the password box and press the Start button. This will start a webserver running on your computer. To control your computer with your tablet you need to open the url http://<address of your computer>:<port set in the menu, default is 1701>, if possible Weylus will display to you the url you need to open.

Weylus uses the uinput interface to simulate input events on Linux. To enable stylus and multi-touch support /dev/uinput needs to be writable by Weylus. To make /dev/uinput permanently writable by your user, run:

sudo groupadd -r uinput
sudo usermod -aG uinput $USER
echo 'KERNEL=="uinput", MODE="0660", GROUP="uinput", OPTIONS+="static_node=uinput"' \
| sudo tee /etc/udev/rules.d/60-weylus.rules

Then, either reboot, or run

sudo udevadm control --reload
sudo udevadm trigger

then log out and log in again. To undo this, run:

sudo rm /etc/udev/rules.d/60-weylus.rules

This allows your user to synthesize input events system-wide, even when another user is logged in. Therefore, untrusted users should not be added to the uinput group.

Weylus needs some permissions to work properly, make sure you enable:

• Incoming connections
• Screen capturing
• Controlling your desktop

I am afraid but as of now Weylus has not been tested on Windows.

That is it, start drawing!

To build Weylus you need to install Rust, Typescript, make, git, a C compiler, nasm and bash. cargo build builds the project. On Linux some additional dependencies are required to build Weylus. On Debian or Ubuntu they can be installed via:

apt-get install -y libx11-dev libxext-dev libxft-dev libxinerama-dev libxcursor-dev libxrender-dev
libxfixes-dev libxtst-dev

Note that building for the first time may take a while as ffmpeg needs to be build. On windows only msvc is supported as C compiler.

In case you do not want to build ffmpeg and libx264 via the supplied build script you have to create the directory deps/dist yourself and copy static ffmpeg libraries built with support for libx264 and a static version of libx264 into deps/dist/lib. Additional deps/dist/include needs to be filled with ffmpeg's include header files. The build script will only try to build ffmpeg if the directory deps/dist does not exist.

Modern browsers expose so called PointerEvents that can convey not only mouse but additionally stylus/pen and touch information. Weylus sets up a webserver with the corresponding javascript code to capture these events. The events are sent back to the server using websockets. Weylus then processes these events using either the generic OS independent backend, which only supports controlling the mouse or on Linux the uinput backend can be used. It makes use of the uinput Linux kernel module which supports creating a wide range of input devices including mouse, stylus and touch input devices.

Either the generic backend is used which is less efficient and only captures the whole screen or on Linux xlib is used to connect to the X-server and do the necessary work of getting window information and capturing the window/screen. To make things fast the "MIT-SHM - The MIT Shared Memory Extension" is used to create shared memory images using XShmCreateImage. The images captured are then encoded to a video stream using ffmpeg. Fragmented MP4 is used as container format to enable browsers to play the stream via the Media Source Extensions API. The video codec used is H.264 as this is widely supported and allows very fast encoding as opposed to formats like AV1. To minimize dependencies ffmpeg is statically linked into Weylus.