Misc. Reference Manual Pages XScreenSaver(3xss)
NAME
XScreenSaver - X11 Screen Saver extension client library
SYNOPSIS
cc [ flag... ] file... -lXss [ library... ]
#include
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; Bool XScreenSaverQueryExtension(Display *dpy, int*event_base_return, int *error_base_return);
Status XScreenSaverQueryVersion(Display *dpy, int*major_version_return, int *minor_version_return);
XScreenSaverInfo *XScreenSaverAllocInfo(void);Status XScreenSaverQueryInfo(Display *dpy, Drawable draw-
able, XScreenSaverInfo *saver_info);
void XScreenSaverSelectInput(Display *dpy, Drawable draw-
able, unsigned long mask);void XScreenSaverSetAttributes(Display *dpy, Drawable draw-
able, int x, int y, unsigned int width, unsigned intheight, unsigned int border_width, int depth, unsigned
int class, Visual *visual, unsigned long valuemask, XSetWindowAttributes *attributes); void XScreenSaverUnsetAttributes(Display *dpy, Drawable drawable); X Version 11 Last change: libXScrnSaver 1.2.0 1 Misc. Reference Manual Pages XScreenSaver(3xss) void XScreenSaverSaverRegister(Display *dpy, int screen, XID xid, Atom type); Status XScreenSaverUnregister(Display *dpy, int screen);Status XScreenSaverGetRegistered(Display *dpy, int screen,
XID *xid, Atom *type); void XScreenSaverSuspend(Display *dpy, Bool suspend);DESCRIPTION
The X Window System provides support for changing the imageon a display screen after a user-settable period of inac-
tivity to avoid burning the cathode ray tube phosphors. However, no interfaces are provided for the user to control the image that is drawn. This extension allows an external ``screen saver'' client to detect when the alternate image is to be displayed and to provide the graphics. 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 providecapabilities similar to those provided by other window sys-
tems. In particular, such users often wish to be able to display corporate logos, instructions on how to reactivatethe screen, and automatic screen-locking utilities. This
extension provides a means for writing such clients. Assumptions This extension exports the notion of a special screen saver window that is mapped above all other windows on a display.This window has the override-redirect attribute set so that
it is not subject to manipulation by the window manager. Furthermore, the X identifier for the window is never returned by QueryTree requests on the root window, so it is typically not visible to other 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 Screen-
SaverNotify events is returned in the value pointed to byevent_base. Since no additional errors are defined by this
extension, the results of error_base are not defined.
X Version 11 Last change: libXScrnSaver 1.2.0 2 Misc. Reference Manual Pages XScreenSaver(3xss)XScreenSaverQueryVersion returns True if the request suc-
ceeded; the values of the major and minor protocol versionssupported by the server are returned in major_version_return
and minor_version_return .
XScreenSaverAllocInfo allocates and returns an XScreenSaver-
Info 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 currentstate 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 iscurrently active and how the til-or-since value should be
interpreted:Off The screen is not currently being saved; til-or-since
specifies the number of milliseconds until the screen saver is expected to activate.On The screen is currently being saved; til-or-since speci-
fies the number of milliseconds since the screen saver activated. DisabledThe screen saver is currently disabled; til-or-since is
zero. The kind field specifies the mechanism that either is currently being used or would have been were the screen being saved: Blanked The video signal to the display monitor was disabled. InternalA server-dependent, built-in screen saver image was
displayed; either no client had set the screen saver window attributes or a different client had the server grabbed when the screen saver activated. External The screen saver window was mapped with attributes set by a client using the ScreenSaverSetAttributes request. The idle field specifies the number of milliseconds since the last input was received from the user on any of the input devices. X Version 11 Last change: libXScrnSaver 1.2.0 3 Misc. Reference Manual Pages XScreenSaver(3xss)The event-mask field specifies which, if any, screen saver
events this client has requested using ScreenSaverSelectIn-
put. XScreenSaverSelectInput asks that events related to the screen saver be generated for this client. If no bits areset in event-mask, then no events will be generated. Other-
wise, any combination of the following bits may be set: ScreenSaverNotify If this bit is set, ScreenSaverNotify events are generated whenever the screen saver is activated or deactivated. ScreenSaverCycle If this bit is set, ScreenSaverNotify events are generated whenever the screen saver cycle interval passes. 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 parentis 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 thebackground-pixmap or cursor attributes may be freed immedi-
ately. The server is free to copy the background-pixmap or
cursor resources or to use them in place; therefore, theeffect of changing the contents of those resources is unde-
fined. 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 toactivity on any of the user input devices, a ForceScreen-
Saver request with a value of Reset, or any request that would cause the window to be unmapped. X Version 11 Last change: libXScrnSaver 1.2.0 4 Misc. Reference Manual Pages XScreenSaver(3xss) 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'sclose down mode has not been RetainPermanent or RetainTem-
porary, 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 immedi-
ately reactivated (such as when switching screen savers),the server may leave the screen saver window mapped (typi-
cally 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 itreturns 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, otherwiseit 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 encoun-
tered or if the property does not exist or is not of thecorrect 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 tothe user while in a non-interactive state. This function is
not intended to be called by an external screensaver appli-
cation. If XScreenSaverSuspend is called multiple times with suspend X Version 11 Last change: libXScrnSaver 1.2.0 5 Misc. Reference Manual Pages XScreenSaver(3xss) 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.ERRORS
XScreenSaverSelectInput, XScreenSaverQueryInfo, XScreen-
SaverSetAttributes and XScreenSaverUnsetAttributes will gen-
erate a BadDrawable error if drawable is not a valid draw-
able identifier. If any undefined bits are set in event-
mask, a BadValue error is generated by XScreenSaverSelectIn-
put . AVAILABILITY XScreenSaverSuspend is available in version 1.1 and later versions of the X Screen Saver Extension. Version 1.1 was first released with X11R7.1.SEE ALSO
X(5) AUTHORS Jim Fulton and Keith Packard. STABILITY This API is considered as experimental. The Xss library major revision may be incremented whenever incompatible changes are done to the API without notice. Use with care.ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes: X Version 11 Last change: libXScrnSaver 1.2.0 6 Misc. Reference Manual Pages XScreenSaver(3xss)____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Availability | x11/library/libxscrnsaver ||_____________________________|_____________________________|
| Interface Stability | Committed ||_____________________________|_____________________________|
| MT-Level | See XInitThreads(3X11) |
|_____________________________|_____________________________|
X Version 11 Last change: libXScrnSaver 1.2.0 7