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 event_mask; /* 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_versionp and minor_versionp .
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
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.