I have had that as a low-intensive side project for the last three years. It's amazing how responsive a virtual touchpad you can create using touch events + HTML 5 + websockets!
Thank you :-) I have been silently reading linked articles and comments here for a couple of years; apparently I needed a reason to push my own semi dormant project as well as an actual computer to finally register.
https://github.com/moses-palmer/virtual-touchpad
Requires >= Python 3.5 though so I won't be trying it out just yet.
Oh, and welcome to Hacker News!