RaspberryPI Touch screen signature network server.
The drawing part of the code based on the "Drawing in response to input" example from developer.gnome.org
The start.c is server part (on RaspberryPI with touch screen).
The wyslij.c is example client part, sending signing requests to the
server and collecting the png image with signature.
Principle of operation described in file operating.md
The program works in three language versions, english, german and polish (my native language).
Instructions for adding new languages in file locale.txt
You can test this on any Linux computer, in the absence of a touch screen you can sign witch a mouse.
In 2.xx version linear interpolation of signature pixels changed to 3rd degree polynomial interpolation.