How to determine that a screensaver is running?

Question

One solution that one could suggest is to periodically look for a special 'Screen-saver' desktop, and if it's present then count it as a running screensaver.

But apparently this is not the case for all screensavers as with some the mentioned desktop is always present.

Are there more reliable solutions for this?

Answer 1

See the WINAPI function SystemParametersInfo() with the SPI_GETSCREENSAVERRUNNING parameter. It's the only documented way to detect whether the screen saver is currently running. (You can also find out if a screen saver is even enabled, get and set the timeout value, and start the screen saver using this function.)

Answer 2

I think the key is to identify the screensaver by its window class ("WindowsScreenSaverClass"). I found this page How do I start, detect and stop screen savers? that has some code examples and explanations.