remouseable

reMouseable

Use your reMarkable tablet as a mouse.

Overview

I'm a user of the reMarkable tablet. After using it for a while I started wondering if it could be used as an input for my computer so I could write and draw on digital whiteboards. It turns out, it can!

There's a great implementation of this feature written in Python at https://github.com/Evidlo/remarkable_mouse. I'm working on this implementation so that I can offer pre-built binaries that don't require a specific language to be installed on the host machine.

Code Documentation

This README contains how-to information for installing, configuration, and using the project. To view the code API documentation check out the godocs.

Usage

Most settings default to the correct values. The only value you should need to set in the common case is the SSH password for the tablet. This password value is found in the settings menu under Help and then Copyrights and licenses. Your password will be near the bottom of the page. If you have an older tablet that has not been updated to the latest software then your password may be found in the About tab of the tablet menu at the bottom of the General Information section. You may either give the password as text with

remouseable --ssh-password="XYZ123"

or you may choose to have a password prompt with:

remouseable --ssh-password="-"

Run one of these commands with your device connected over USB and your stylus will become a mouse. The stylus is actually active before it touches the screen. This means you can see your mouse move by hovering the stylus just above the writing surface but without directly touching the tablet. Once you touch the tablet surface with the stylus the computer mouse will click and hold down the left mouse button while you write or draw and then release the button when you lift the stylus.

OSX Privacy Settings

If you are using this on an Apple or OSX device then you will need to give the terminal or shell you are using permissions to control your mouse. Mouse permissions are treated as an accessibility feature. If you are not prompted by the operating system to update your permissions the first time you run the application then you can navigate to System Preferences -> Security & Privacy -> Privacy -> Accessibility. You will see your terminal or shell in the list of applications that have requested accessibility permissions.

reMarkable 2 Tablets

The application should work with both reMarkable and reMarkable 2 tablets. However, the reMarkable 2 requires that you add --event-file /dev/input/event1 when executing because of a slight change in where the stylus events are written in the new tablets. The full command should look like remousable --ssh-password="MYPASSWORD" --event-file="/dev/input/event1".

Wireless Tablet

The default expectation is that you will have your tablet connected over USB which makes the default 10.11.99.1 address available. However, it is also possible to access your device over wifi. If you attempt this method then you will need to arrange for a static, or at least consistent, IP address for the tablet. This is something you can usually do through configuring your router to assign a fixed IP address to the device based on the hardware MAC address.

If you cannot assign the same 10.11.99.1 address in your setup then you may override the default IP address when running the application:

Advanced SSH Setup

By default, the tablet only accepts the root password for authentication. It is possible, though, to install a custom public key on the device so that you can use either password-less authentication or use a key pair that is encrypted with the password of your choice rather than the device's default password.

If you'd like to create a key pair especially for accessing the reMarkable tablet then start with a guide like https://help.github.com/en/articles/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent that walks through creating a new key pair and registering it with your SSH agent. For even more advanced SSH users, such as those using the gpg-agent as the SSH agent, the remouseable application will talk to any valid SSH agent implementation so long as the SSH_AUTH_SOCK value is set correctly.

Once you have a key pair ready, copy the public key value from ssh-add -L for the key you want to use. Then copy the key over to your tablet with:

ssh root@10.11.99.1 # This will prompt for password.
mkdir -p ~/.ssh # This directory does not exist by default.
echo 'INSERT YOUR PUBLIC KEY HERE' >> ~/.ssh/authorized_keys

Now future connections over SSH will leverage your key pair and you can omit the usual password flag when running the application.

Note that windows builds cannot use this option due to incompatibilities with the current version of the windows ssh-agent.

Note that if you encounter the Invalid MIT-MAGIC-COOKIE-1 key error it means that most likely the ssh fingerprint of the device might have changed to an update of the tablet OS. Follow the ssh suggestion of removing the outdated fingerprint then if you are satisfied that your device is indeed the right one try connecting again.

remouseable --ssh-ip="192.168.1.110" # or other IP

All Options

$ remouseable -h
Usage of remouseable:
      --debug-events             Stream hardware events from the tablet instead of acting as a mouse. This is for debugging.
      --disable-drag-event       Disable use of the custom OSX drag event. Only use this drawing on an Apple device is not working as expected.
      --event-file string        The path on the tablet from which to read evdev events. Probably don't change this. (default "/dev/input/event0")
      --orientation string       Orientation of the tablet. Choices are vertical, right, and left (default "right")
      --pressure-threshold int   Change the click detection sensitivity. 1000 is when the pen makes contact with the tablet. Set higher to require more pen pressure for a click. (default 1000)
      --screen-height int        The max units per millimeter of the host screen height. Probably don't change this. (default 1080)
      --screen-width int         The max units per millimeter of the host screen width. Probably don't change this. (default 1920)
      --ssh-ip string            The host and port of a tablet. (default "10.11.99.1:22")
      --ssh-password string      An optional password to use when ssh-ing into the tablet. Use - for a prompt rather than entering a value. If not given then public/private keypair authentication is used.
      --ssh-socket string        Path to the SSH auth socket. This must not be empty if using public/private keypair authentication.
      --ssh-user string          The ssh username to use when logging into the tablet. (default "root")
      --tablet-height int        The max units per millimeter for the hight of the tablet. Probably don't change this. (default 15725)
      --tablet-width int         The max units per millimeter for the width of the tablet. Probably don't change this. (default 20967)
pflag: help requested
exit status 2

Building

There are pre-built binaries attached to each release that should work for all 64bit versions of linux, osx, and windows. However, if you prefer to generate your own build then the following sections detail building a binary on different platforms.

Linux

Linux builds are dependent on:

• gcc
• x11 dev headers
• xtst dev headers
• xorg dev headers

These package will vary by name depending on your chosen linux distro. Debian and Ubuntu users can install these with:

apt-get install -y gcc libc6-dev libx11-dev xorg-dev libxtst-dev

From there you run make build.

OSX

OSX builds will require xcode and the xcode command line tools. These must be installed through the Apple store.

Beyond xcode the build also requires installing support for gnu make if you want to use the Makefile for generating a build. Homebrew users can install this with:

brew install make coreutils findutils gnu-tar gnu-sed gawk gnutls gnu-indent gnu-getopt grep
export PATH="$(brew --prefix)/opt/make/libexec/gnubin:${PATH}"

From there you run make build.

Windows

Windows builds require a GCC implementation. I recommend https://jmeubank.github.io/tdm-gcc/. During installation you will be given the option to add the GCC install to your path. If you choose not to then you will need to temporarily add it to your path in PowerShell with:

$env:Path += ";C:\TDM-GCC-64\bin\"

The included Makefile contains too many bash specific commands to work in PowerShell but you can still generate a binary by running:

go build main.go

Windows On Linux

If you want to generate a windows build from a linux machine then you will need to install a MinGW implementation. Debian and Ubuntu users can do this with:

apt-get install -y gcc-multilib gcc-mingw-w64

The included Makefile does not have a build option for this but you can generate the binary with:

CC=x86_64-w64-mingw32-gcc GOOS=windows go build main.go

How It Works

The project is implemented as a set of successive layers that turn the tablet into a mouse. It follows as:

• SSH into the device and start streaming evdev data back to the host.
• Convert the raw byte stream into structured evdev data containers.
• Feed all events into a state machine that emits higher level state change events like "CLICK" and "MOVE".
• Use state change events as a trigger for moving or clicking the mouse on the host machine.

Each of these layers has an interface defined in the pkg/domain.go file.

The mouse interactions on the host are performed by using a modified version of https://github.com/go-vgo/robotgo. The pkg/internal/robotgo directory contains a stripped down version of robotgo that contains only the portions required to detect the screen dimensions and send mouse events. The actual robotgo project contains support for a much larger set of features such as taking screen shots and controlling windows on the screen. However, each of those additional features comes with additional system dependencies that make creating a portable binary build difficult.

License

remouseable is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License version 3 as published
by the Free Software Foundation.

remouseable is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with remouseable.  If not, see <https://www.gnu.org/licenses/>

Developing

This project is go1.16+ compatible. A Makefile is included to make some things easier. Some make targets of note:

• make generate

  Re-generate any automatically generated code. Note that there is a gomock bug making it necessary to manually modify the files after generation because it adds a cyclical import.

• make test

  Run all the unit tests and generate a coverage report in .coverage/.

• make lint

  Run the golangci-lint suite using the included configuration.

• make fmt

  Apply goimports formatting.

• make build

  Generate a binary from the current project state.

• make tools

  Generate a .bin/ directory that contains a built version of each of the tools used to build and test the project.

• make update / make updatetools

  Run go get -u for the project or for the project tooling.

• make clean / make cleantools / make cleancoverage

  Remove files generated by the Makefile. The top-level clean should remove all artifacts such as ./bin and ./coverage. The other are scoped to specific artifacts for cases where, for example, you want to remove old coverage reports and regenerate them.

Thanks

I used the https://github.com/gvalkov/golang-evdev project as a reference when implementing the evdev parser. I didn't use it directly because it is very much oriented towards directly opening and managing a file descriptor for a device. This project needs to read data from a remote device.

Future Features

The current state of this project fulfills all of my needs so I'm not planning on adding anything new for myself. However, I'm open to helping and reviewing contributions if you want add a new feature or make an improvement. Open an issue with your idea if you want to talk about how it would best be added.