Captures a part of the current render target and returns the data as a binary string in the given format.
Since the pixel buffer clears itself every frame, this will return a black screen outside of. To capture the user's final view, use GM:PostRender. This will not capture the Steam overlay or third-party injections (such as the Discord overlay, Overwolf, and advanced cheats) on the user's screen.
Issue Tracker: 2571
How you could use this to save a picture of your screen.
garrysmod/datafolder, containing a screenshot.