XSetScreenSaver man page

int XSetScreenSaver(Display *display, int timeout, int interval, int prefer_blanking, int allow_exposures);

int XForceScreenSaver(Display *display, int mode);

int XActivateScreenSaver(Display *display);

int XResetScreenSaver(Display *display);

int XGetScreenSaver(Display *display, int *timeout_return, int *interval_return, int *prefer_blanking_return, int *allow_exposures_return);

allow_exposures

Specifies the screen save control values. You can pass DontAllowExposures, AllowExposures, or DefaultExposures.

allow_exposures_return

Returns the current screen save control value (DontAllowExposures, AllowExposures, or DefaultExposures).

display

Specifies the connection to the X server.

interval

Specifies the interval, in seconds, between screen saver alterations.

interval_return

Returns the interval between screen saver invocations.

mode

Specifies the mode that is to be applied. You can pass ScreenSaverActive or ScreenSaverReset.

prefer_blanking

Specifies how to enable screen blanking. You can pass DontPreferBlanking, PreferBlanking, or DefaultBlanking.

prefer_blanking_return

Returns the current screen blanking preference (DontPreferBlanking, PreferBlanking, or DefaultBlanking).

timeout

Specifies the timeout, in seconds, until the screen saver turns on.

timeout_return

Returns the timeout, in seconds, until the screen saver turns on.

Timeout and interval are specified in seconds.  A timeout of 0 disables the screen saver  (but an activated screen saver is not deactivated), and a timeout of -1 restores the default. Other negative values generate a BadValue error. If the timeout value is nonzero,  XSetScreenSaver enables the screen saver. An interval of 0 disables the random-pattern motion. Both values are limited to a 16-bit signed integer range by the wire protocol, despite the C prototype. If no input from devices (keyboard, mouse, and so on) is generated  for the specified number of timeout seconds once the screen saver is enabled, the screen saver is activated.

For each screen,  if blanking is preferred and the hardware supports video blanking,  the screen simply goes blank.   Otherwise, if either exposures are allowed or the screen can be regenerated  without sending  Expose events to clients,  the screen is tiled with the root window background tile randomly  re-origined each interval seconds. Otherwise, the screens' state do not change,  and the screen saver is not activated. The screen saver is deactivated, and all screen states are restored at the next keyboard or pointer input or at the next call to XForceScreenSaver with mode ScreenSaverReset.

If the server-dependent screen saver method supports periodic change, the interval argument serves as a hint about how long the change period should be, and zero hints that no periodic change should be made. Examples of ways to change the screen include scrambling the colormap periodically, moving an icon image around the screen periodically, or tiling the screen with the root window background tile, randomly re-origined periodically.

XSetScreenSaver can generate a BadValue error.

If the specified mode is  ScreenSaverActive and the screen saver currently is deactivated, XForceScreenSaver activates the screen saver even if the screen saver had been disabled with a timeout of zero. If the specified mode is  ScreenSaverReset and the screen saver currently is enabled, XForceScreenSaver deactivates the screen saver if it was activated, and the activation timer is reset to its initial state  (as if device input had been received).

XForceScreenSaver can generate a BadValue error.

The XActivateScreenSaver function activates the screen saver.

The XResetScreenSaver function resets the screen saver.

The XGetScreenSaver function gets the current screen saver values.

BadValue

Some numeric value falls outside the range of values accepted by the request. Unless a specific range is specified for an argument, the full range defined by the argument's type is accepted.  Any argument defined as a set of alternatives can generate this error.

Xlib - C Language X Interface

XActivateScreenSaver(3), XForceScreenSaver(3), XGetScreenSaver(3) and XResetScreenSaver(3) are aliases of XSetScreenSaver(3).