It looks like the waveshare e-paper screens are all SPI interface? The Xojo docs for the Pi show that it wraps the WiringPi library so as long as that is installed you should be able to use the SPI interface. More info on that here:
the install and setup for the wiringPi library you have probably already done or the thing might not work in the first place, but they are here:
I dont see any specific spi libraries for xojo, so Im not sure off the top of my head if there is something built in we can use or if we need to wrap the spi calls in a declare to the wiring pi library. The best example, actually the only example that I could find but I did not do an exhaustive search anywhere, was Einhugers talking to a barometric pressure sensor over SPI. He uses a declare to the wiringpi library.
If you have a look at the official Xojo GPIO module that also talks to the wiringpi library it also uses declares so perhaps that is the best way to go. You can download their classes and code and have a look at how they are doing it too, though these are not specifically SPI declares, they will show the format and what works and how to create a re-usable xojo class to talk to the thing:
now the tricky bit will be to rebuild code that will talk directly to the display. I don t know how its commands differ from a standard LCD or anything else but I doubt you can reuse any of that other code that might be out there. The low level commands are documented on the data sheet for the display which is here:
well, thats for the 2.7 inch, you may have to dig up the proper one for your display. Unfortunately they are pretty low level. You should be able to send them using the spi library and xojo but its not going to be particularly pretty to figure out and get working.
You can look at the very low level python code that talks directly to the display and it doesnt look like it would be too horrific of a job to port it to xojo. Those modules are in the waveshare github repository here:
pick the one that is for your particular device and start porting to xojo. Most of the stuff is pretty straight forward but I do see some low level bit manipulation in there that might be confusing to just read and convert.
If you create another open source github project and talk to people here on the list about it there might be some help forthcoming from the rest of the community But it wont happen overnight. I dont even have one of these displays to play with.