Manual Pages for UNIX Operating System command usage for man XGetEventData

XLIB FUNCTIONS                                XGetEventData(3x11)



NAME
     XGetEventData, XFreeEventData, XGenericEventCookie -
     retrieve and free additional event data through cookies.

SYNTAX
     cc [ flag... ] file... -lX11 [ library... ]

     Bool XGetEventData(Display *display, XGenericEventCookie
          *cookie);

     void XFreeEventData(Display *display, XGenericEventCookie
          *cookie);


ARGUMENTS
     display   Specifies the connection to the X server.

     cookie    Specifies the cookie to free or retrieve the data
               for.


STRUCTURES
     typedef struct {
          int type;
          unsigned long serial;
          Bool send_event;
          Display *display;
          int extension;
          int evtype;
          unsigned int cookie;
          void *data;
     } XGenericEventCookie;


DESCRIPTION
     Some extension XGenericEvents require additional memory to
     store information.  For these events, the library returns a
     XGenericEventCookie with a token ('cookie') unique to this
     event. The XGenericEventCookie's data pointer is undefined
     until XGetEventData is called.

     The XGetEventData function retrieves this extra data for the
     given cookie. No round-trip to the server is required. If
     the cookie is invalid or the event is not an event handled
     by cookie handlers, False is returned. If XGetEventData
     returns True, the cookie's data pointer points to the memory
     containing the event information. A client must call
     XFreeEventData to free this memory.  XGetEventData returns
     False for multiple calls for the same event cookie.

     The XFreeEventData function frees the data associated with a
     cookie. A client must call XFreeEventData for each cookie



X Version 11        Last change: libX11 1.3.5                   1






XLIB FUNCTIONS                                XGetEventData(3x11)



     claimed with XGetEventData.


EXAMPLE CODE
     XEvent event;
     XGenericEventCookie *cookie = &ev;

     XNextEvent(display, &event);
     if (XGetEventData(display, cookie)) {
         handle_cookie_event(cookie->data);
     } else
         handle_event(&event);
     }
     XFreeEventData(display, cookie);


NOTES
     A cookie is defined as unclaimed if it has been returned to
     the client through XNextEvent but its data has not been
     retrieved via XGetEventData.  Subsequent calls to XNextEvent
     may free memory associated with unclaimed cookies.  Multi-
     threaded X clients must ensure that XGetEventData is called
     before the next call to XNextEvent.


SEE ALSO
     XNextEvent(3x11),
     Xlib - C Language X Interface



ATTRIBUTES
     See attributes(5) for descriptions of the following attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Availability                | x11/library/libx11          |
    |_____________________________|_____________________________|
    | Interface Stability         | Committed                   |
    |_____________________________|_____________________________|
    | MT-Level                    | See XInitThreads(3X11)      |
    |_____________________________|_____________________________|











X Version 11        Last change: libX11 1.3.5                   2