Writing screensavers.

Does anyone know where I can find information on invoking a screen saver and being able to configure it?
Many years ago, I used !Delerium quite successfully and was able to add my routines to the front end, but that is not now compatible.
I have managed to get something up and running in BASIC, using code from some of the supplied screen savers, but I would rather have a better understanding of the basics and write my own code, rather than rob someone elses. Although if the methods needed are fairly straightforward, then most code would look very similar.

The docs I have are from the initial dev (3.8/4)

http://www.4corn.co.uk/archive/Acorn_DeveloperSite/reference/ro4/api/html/screensaver.html

Someone else might have something newer?

Wow! That was quicker than I expected.
At first glance, it looks like what I was after.
Thanks.

I used !Delerium quite successfully and was able to add my routines to the front end, but that is not now compatible.

It isn’t? This page seems to say it is
http://www.filebase.org.uk/software/graphics/269

That page links to this sourceforge page: http://delirium-saver.sourceforge.net/

Ok, the version I had on my RPC didn’t work on the RPi when I copied it over.
I will follow up the !Delerium route if I’m struggling to achieve what I want directly.
Thanks.

No trouble.