Each rally is written as a short code that describes the point shot by shot.
The notation comes from the Match Charting Project, a project that records pro matches by hand. If you're curious, here's their beginner's guide : https://www.tennisabstract.com/blog/2015/09/23/the-match-cha....
In that system a rally looks like "5f2f3b3b1w#", where each character is one shot : where it landed, forehand or backhand, and how the point finally ended.
For this project I picked the match-winning rallies they've recorded so far (the open dataset is here : https://github.com/JeffSackmann/tennis_MatchChartingProject), so every poster is the very last point of a match.
You can also type in any sequence you like and make your own custom poster.
You can then tweak the look. The shape of the curves, the court, the surface, and the colors, either by type of shot or by player.
Happy to hear your feedback on it. Have fun with it!