XmuDisplayQueue(Xmu)     X Version 11 (Release 5)       XmuDisplayQueue(Xmu)
                                6 January 1993


 Name

    XmuDisplayQueue - display queue functions

 Syntax


    cc  . . .  -lXmu


    #include <X11/Xmu/DisplayQue.h>

    XmuDisplayQueue *XmuDQCreate(closefunc, freefunc, data)
          int (*closefunc)();
          int (*freefunc)();
          caddr_t data;

    XmuDisplayQueueEntry *XmuDQAddDisplay(q, dpy, data)
          XmuDisplayQueue *q;
          Display *dpy;
          caddr_t data;

    XmuDisplayQueueEntry *XmuDQLookupDisplay(q, dpy)
          XmuDisplayQueue *q;
          Display *dpy;

    Bool XmuDQRemoveDisplay(q, dpy)
          XmuDisplayQueue *q;
          Display *dpy;

    Bool XmuDQDestroy(q, docallbacks)
         XmuDisplayQueue *q;
         Bool docallbacks;


 Arguments


    q            Specifies the queue to be acted on.

    dpy          Specifies the display to add, lookup or remove.

    data         Specifies private data for the function or free function.

    docallbacks  Specifies whether close functions should be called.

    closefunc    Specifies the close function.

    freefunc     Specifies the free function.


 Description

    The XmuDQCreate function creates and returns an empty XmuDisplayQueue
    (which is really just a set of displays, but is called a queue for his-
    torical reasons).  The queue is initially empty, but displays can be
    added using XmuAddDisplay.  The data value is simply stored in the queue
    for use by the closefunc and freefunc callbacks.  Whenever a display in
    the queue is closed using XCloseDisplay, the closefunc (if non-NULL) is
    called with the queue and the display's XmuDisplayQueueEntry as follows:

       (*closefunc) (queue,entry)

    The freeproc (if non-NULL) is called whenever the last display in the
    queue is closed, as follows:

       (*freefunc) (queue)

    The application is responsible for actually freeing the queue, by calling
    XmuDQDestroy.

    The XmuDQAddDisplay function adds the specified display to the queue.  If
    successful, the queue entry is returned, otherwise NULL is returned.  The
    data value is simply stored in the queue entry for use by the queue's
    freefunc callback.  This function does not attempt to prevent duplicate
    entries in the queue; the caller should use XmuDQLookupDisplay to deter-
    mine if a display has already been added to a queue.

    The XmuDQLookupDisplay function returns the queue entry for the specified
    display, or NULL if the display is not in the queue.

    This macro returns the number of displays in the specified queue.

       XmuDQNDisplays(q)

    The XmuDQRemoveDisplay function removes the specified display from the
    specified queue.  No callbacks are performed.  If the display is not
    found in the queue, False is returned, otherwise True is returned.

    The XmuDQDestroy function releases all memory associated with the speci-
    fied queue.  If docallbacks is True, then the queue's closefunc callback
    (if non-NULL) is first called for each display in the queue, even though
    XCloseDisplay is not called on the display.

 Structures


    typedef struct _XmuDisplayQueueEntry {
         struct _XmuDisplayQueueEntry *prev, *next;
         Display *display;
         CloseHook closehook;
         caddr_t data;
    } XmuDisplayQueueEntry;
    typedef struct _XmuDisplayQueue {
         int nentries;
         XmuDisplayQueueEntry *head, *tail;
         int (*closefunc)();
         int (*freefunc)();
         caddr_t data;
    } XmuDisplayQueue;


 See also

    XOpenDisplay(XS)
    Xlib - C Language X Interface