How to get the last windows active time by windows api

Question

In general, the Screensaver will run when we do nothing for a period of time.
Now i wanna know how to get the unactive time.
In another word,i want to make a progr

Answer 1

Look into CallNtPowerInformation() and request a SYSTEM_POWER_INFORMATION structure.

Answer 2

The CallNtPowerInformation() API is to get the last power information
I should use GetLastInputInfo()