NAME

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

SYNTAX

       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 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(3),
       Xlib - C Language X Interface

X Version 11                                      libX11 1.6.2                                  XGetEventData(3)