typedef struct {
Window window; /* screen saver window */
int state; /* ScreenSaver{Off,On,Disabled} */
int kind; /* ScreenSaver{Blanked,Internal,External} */
unsigned long til_or_since; /* milliseconds */
unsigned long idle; /* milliseconds */
unsigned long eventMask; /* events */
} XScreenSaverInfo;
typedef struct {
int type; /* of event */
unsigned long serial; /* # of last request processed by server */
Bool send_event; /* true if this came frome a SendEvent request */
Display *display; /* Display the event was read from */
Window window; /* screen saver window */
Window root; /* root window of event screen */
int state; /* ScreenSaver{Off,On,Cycle} */
int kind; /* ScreenSaver{Blanked,Internal,External} */
Bool forced; /* extents of new region */
Time time; /* event timestamp */
} XScreenSaverNotifyEvent;
Current X server implementations typically provide at least one form of ``screen saver'' image. Historically, this has been a copy of the X logo drawn against the root background pattern. However, many users have asked for the mechanism to allow them to write screen saver programs that provide capabilities similar to those provided by other window systems. In particular, such users often wish to be able to display corporate logos, instructions on how to reactivate the screen, and automatic screen-locking utilities. This extension provides a means for writing such clients.
XScreenSaverQueryExtension returns True if the XScreenSaver extension is available on the given display. A client must call XScreenSaverQueryExtension before calling any other XScreenSaver function in order to negotiate a compatible protocol version; otherwise the client will get undefined behavior (XScreenSaver may or may not work).
If the extension is supported, the event number for ScreenSaverNotify events is returned in the value pointed to by event_base. Since no additional errors are defined by this extension, the results of error_base are not defined.
XScreenSaverQueryVersion returns True if the request succeeded; the values of the major and minor protocol versions supported by the server are returned in major_version_return and minor_version_return .
XScreenSaverAllocInfo allocates and returns an XScreenSaverInfo structure for use in calls to XScreenSaverQueryInfo. All fields in the structure are initialized to zero. If insufficient memory is available, NULL is returned. The results of this routine can be released using XFree.
XScreenSaverQueryInfo returns information about the current state of the screen server in saver_info and a non-zero value is returned. If the extension is not supported, saver_info is not changed and 0 is returned.
The state field specifies whether or not the screen saver is currently active and how the til-or-since value should be interpreted:
The kind field specifies the mechanism that either is currently being used or would have been were the screen being saved:
The idle field specifies the number of milliseconds since the last
input was received from the user on any of the input devices.
The event-mask field specifies which, if any, screen saver
events this client has requested using ScreenSaverSelectInput.
XScreenSaverSelectInput asks that events related to the screen saver be generated for this client. If no bits are set in event-mask, then no events will be generated. Otherwise, any combination of the following bits may be set:
XScreenSaverSetAttributes
sets the attributes to be used
the next time the external screen saver is activated.
If another client currently has the attributes set,
a BadAccess error is generated and the request is ignored.
Otherwise, the specified window attributes are checked as if
they were used in a core CreateWindow request whose
parent is the root.
The override-redirect field is ignored as it is implicitly set
to True.
If the window attributes result in an error according to the rules for
CreateWindow, the request is ignored.
Otherwise, the attributes are stored and will take effect on the next
activation that occurs when the server is not grabbed by another client.
Any resources specified for the
background-pixmap or cursor attributes may be
freed immediately.
The server is free to copy the background-pixmap or cursor
resources or to use them in place; therefore, the effect of changing
the contents of those resources is undefined.
If the specified colormap no longer exists when the screen saver
activates, the parent's colormap is used instead.
If no errors are generated by this request, any previous screen saver
window attributes set by this client are released.
When the screen saver next activates and the server is not grabbed by
another client, the screen saver window is
created, if necessary, and set to the specified attributes and events
are generated as usual.
The colormap associated with the screen saver window is installed.
Finally, the screen saver window is mapped.
The window remains mapped and at the top of the stacking order
until the screen saver is deactivated in response to activity on
any of the user input devices, a ForceScreenSaver request with
a value of Reset, or any request that would cause the window to be
unmapped.
If the screen saver activates while the server is grabbed by another
client, the internal saver mechanism is used.
The ForceScreenSaver request may be used with a value of Active
to deactivate the internal saver and activate the external saver.
If the screen saver client's connection to the server is broken
while the screen saver is activated and the client's close down mode has not
been RetainPermanent or RetainTemporary, the current screen saver
is deactivated and the internal screen saver is immediately activated.
When the screen saver deactivates, the screen saver window's colormap
is uninstalled and the window is unmapped (except as described below).
The screen saver XID is disassociated
with the window and the server may, but is not required to,
destroy the window along with any children.
When the screen saver is being deactivated and then immediately
reactivated (such as when switching screen savers), the server
may leave the screen saver window mapped (typically to avoid
generating exposures).
XScreenSaverUnsetAttributes instructs the server to discard any previous screen saver window attributes set by this client.
XScreenSaverRegister stores the given XID in the _SCREEN_SAVER_ID property (of the given type) on the root window of the specified screen. It returns zero if an error is encountered and the property is not changed, otherwise it returns non-zero.
XScreenSaverUnregister removes any _SCREEN_SAVER_ID from the root window of the specified screen. It returns zero if an error is encountered and the property is changed, otherwise it returns non-zero.
XScreenSaverGetRegistered returns the XID and type stored in the _SCREEN_SAVER_ID property on the root window of the specified screen. It returns zero if an error is encountered or if the property does not exist or is not of the correct format; otherwise it returns non-zero.
XScreenSaverSuspend
temporarily suspends the screensaver and DPMS timer if suspend
is 'True', and restarts the timer if suspend is 'False'.
This function should be used by applications that don't want the
screensaver or DPMS to become activated while they're for example in
the process of playing a media sequence, or are otherwise continuously
presenting visual information to the user while in a non-interactive
state. This function is not intended to be called by an external
screensaver application.
If XScreenSaverSuspend is called multiple times with suspend
set to 'True', it must be called an equal number of times with
suspend set to 'False' in order for the screensaver timer to be
restarted. This request has no affect if a client tries to resume the
screensaver without first having suspended it.
XScreenSaverSuspend can thus not be used by one client to resume
the screensaver if it's been suspended by another client.
If a client that has suspended the screensaver becomes disconnected from
the X server, the screensaver timer will automatically be restarted, unless
it's still suspended by another client. Suspending the screensaver timer
doesn't prevent the screensaver from being forceably activated with the
ForceScreenSaver request, or a DPMS mode from being set with the
DPMSForceLevel request.
XScreenSaverSuspend also doesn't deactivate the screensaver or DPMS
if either is active at the time the request to suspend them is received by
the X server. But once they've been deactivated, they won't automatically
be activated again, until the client has canceled the suspension.