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XScreenSaver(3)                                                XScreenSaver(3)




NAME

       XScreenSaver - X11 Screen Saver extension client library


SYNOPSIS

       #include <X11/extensions/scrnsaver.h>

       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_ver-
              sion_return, int *minor_version_return);

       XScreenSaverInfo *XScreenSaverAllocInfo(void);

       Status  XScreenSaverQueryInfo(Display *dpy, Drawable drawable, XScreen-
              SaverInfo *saver_info);

       void XScreenSaverSelectInput(Display *dpy, Drawable drawable,  unsigned
              long mask);

       void  XScreenSaverSetAttributes(Display *dpy, Drawable drawable, int x,
              int y, unsigned int width, unsigned  int  height,  unsigned  int
              border_width,  int  depth,  unsigned  int class, Visual *visual,
              unsigned long valuemask, XSetWindowAttributes *attributes);

       void XScreenSaverUnsetAttributes(Display *dpy, Drawable drawable);

       void XScreenSaverRegister(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 image on  a  dis-
       play screen after a user-settable period of inactivity 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  pro-
       grams that provide capabilities similar to those provided by other win-
       dow systems.  In particular, such users often wish to be able  to  dis-
       play corporate logos, instructions on how to reactivate the 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 manipula-
       tion by the window manager.  Furthermore, the X identifier for the win-
       dow  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 XScreenSaver-
       QueryExtension 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 struc-
       ture for use in calls to  XScreenSaverQueryInfo.   All  fields  in  the
       structure  are  initialized  to zero.  If insufficient memory is avail-
       able, 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:

       Off The screen is not currently being saved; til-or-since specifies the
           number of milliseconds until the screen saver is expected to  acti-
           vate.

       On  The  screen  is  currently  being saved; til-or-since specifies the
           number of milliseconds since the screen saver activated.

       Disabled
           The 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.

       Internal
           A  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 acti-
           vated.

       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.
       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:

       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  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; there-
       fore, the effect 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 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  chil-
       dren.
       When the screen saver is being deactivated and then immediately reacti-
       vated (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 previ-
       ous screen saver window attributes set by this client.

       XScreenSaverRegister stores the given XID in the _SCREEN_SAVER_ID prop-
       erty  (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 win-
       dow of the specified screen.  It returns zero if an  error  is  encoun-
       tered 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 with-
       out 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 force-
       ably 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 automati-
       cally be activated again, until the client has canceled the suspension.


ERRORS

       XScreenSaverSelectInput,    XScreenSaverQueryInfo,   XScreenSaverSetAt-
       tributes and XScreenSaverUnsetAttributes will  generate  a  BadDrawable
       error if drawable is not a valid drawable identifier.  If any undefined
       bits are set in event-mask, a BadValue error is generated by XScreenSa-
       verSelectInput .



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(7)


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.



X Version 11                  libXScrnSaver 1.2.3              XScreenSaver(3)

libXScrnSaver 1.2.3 - Generated Fri Aug 24 08:43:27 CDT 2018
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