Weylus
Weylus turns your tablet or smart phone into a graphic tablet/touch screen for your computer!
Table of Contents
Features
•
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
•
Hardware accelerated video encoding
•
Tablet as second screen
Installation
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.
Running
Start Weylus, preferably set an access code in the access code 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 and show a QR code with the encoded address. If you have a firewall running make sure to open a TCP port for the webserver (1701 by default) and the websocket connection (9001 by default).
Fullscreen
You may want to add a bookmark to your home screen on your tablet as this enables running Weylus in full screen mode (on iOS/iPadOS this needs to be done with Safari).
Linux
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
Plain Text
복사
Then, either reboot, or run
sudo udevadm control --reload
sudo udevadm trigger
Plain Text
복사
then log out and log in again. To undo this, run:
sudo rm /etc/udev/rules.d/60-weylus.rules
Plain Text
복사
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.
Hardware Acceleration
On Linux Weylus supports hardware accelerated video encoding through the Video Acceleration API (VAAPI) or Nvidia's NVENC. By default hardware acceleration is disabled as quality and stability of the hardware encoded video stream varies widely among different hardware and sufficient quality can not be guaranteed. If VAAPI is used it is possible to select a specific driver by setting the environment variable LIBVA_DRIVER_NAME. You can find possible values with the command ls /usr/lib/dri/ | sed -n 's/^\(\S*\)_drv_video.so$/\1/p'. Additionally you can specify the VAAPI device to use by setting WEYLUS_VAAPI_DEVICE; by default devices can be found in /dev/dri. Note that you may need to install the driver(s) first.
Nvidias NVENC is very fast but delivers a video stream of noticeably lower quality (at least on my GeForce GTX 1050 Mobile GPU) but more recent GPUs should provide higher quality. For this to work nvidia drivers need to be installed.
Weylus as Second Screen
On Linux Weylus can be used to turn your tablet into a second screen if your hardware supports it.
But first a word of waring: The following configuration may break starting the X server. This means you might end up without a graphical login or X may get stuck and just display a black screen. So make sure you know what you are doing or are at least able to recover from a broken X server.
You will need to install the xf86-video-intel driver and create the file /etc/X11/xorg.conf.d/20-intel.conf with the following contents:
Section "Device"
Identifier "intelgpu0"
Driver "intel"
# this adds two virtual monitors / devices
Option "VirtualHeads" "2"
# if your screen is flickering one of the following options might help
Option "TripleBuffer" "true"
Option "TearFree" "true"
Option "DRI" "false"
EndSection
Plain Text
복사
After a reboot xrandr will show two additional monitors VIRTUAL1 and VIRTUAL2 and can be used to configure them. To activate VIRTUAL1 with a screen size of 1112x834 and a refresh rate of 60 fps the following commands can be used:
> # this generates all input parameters xrandr needs
> #from a given screen resolution and refresh rate
> gtf 1112 834 60
# 1112x834 @ 60.00 Hz (GTF) hsync: 51.78 kHz; pclk: 75.81 MHz
Modeline "1112x834_60.00" 75.81 1112 1168 1288 1464 834 835 838 863 -HSync +Vsync
> # setup the monitor
> xrandr --newmode "1112x834_60.00" 75.81 1112 1168 1288 1464 834 835 838 863 -HSync +Vsync
> xrandr --addmode VIRTUAL1 1112x834_60.00
> xrandr --output VIRTUAL1 --mode 1112x834_60.00
> # check if everything is in order
> xrandr
Plain Text
복사
Now you should be able to configure this monitor in your system setting like a regular second monitor and for example set its position relative to your primary monitor.
After setting up the virtual monitor start Weylus and select it in the capture menu. You may want to enable displaying the cursor in this case. That is it!
macOS
Weylus needs some permissions to work properly, make sure you enable:
•
Incoming connections
•
Screen capturing
•
Controlling your desktop
Windows
I am afraid but as of now Weylus has not been tested on Windows.
Building
To build Weylus you need to install Rust, Typescript, make, git, a C compiler, nasm and bash. cargo build builds the project. By default Weylus is build in debug mode, if you want a release build run cargo build --release. 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 libxrandr-dev libxcomposite-dev libxi-dev libxv-dev autoconf libtool-bin \
nvidia-cuda-dev pkg-config libdrm-dev
Plain Text
복사
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.
Docker
It is also possible to build the Linux version inside a docker container. The Dockerfile used is located at docker/Dockerfile. This is also how the official release is built. Building works like this:
docker run -it hhmhh/weylus_build bash
root@f02164dbfa18:/# git clone https://github.com/H-M-H/Weylus
Cloning into 'Weylus'...
remote: Enumerating objects: 10, done.
remote: Counting objects: 100% (10/10), done.
remote: Compressing objects: 100% (7/7), done.
remote: Total 827 (delta 1), reused 6 (delta 0), pack-reused 817
Receiving objects: 100% (827/827), 5.38 MiB | 7.12 MiB/s, done.
Resolving deltas: 100% (431/431), done.
root@f02164dbfa18:/# cd Weylus/
root@f02164dbfa18:/Weylus# cargo deb
Compiling
...
Plain Text
복사
Once the build is finished you can for example copy the binary from the container to your file system like this:
docker cp f02164dbfa18:/Weylus/target/release/weylus ~/some/path/weylus
Plain Text
복사
The .deb is located at /Weylus/target/debian/. Please note that the container ID will most likely not be f02164dbfa18 if you run this yourself, replace it accordingly.
How does this work?
Stylus/Touch
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.
Screen mirroring & window capturing
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.
