Linux Cubed Series 3: Developer Tools/Linux Cubed Series 3 - Developer Tools.iso/devel/lang/lisp/stk-3.002/stk-3/STk-3.1/Tk/unix/tkUnixEvent.c

C/C++ Source or Header | 1996-05-31 | 5.1 KB | 195 lines

/*
 * tkUnixEvent.c --
 *
 *    This file implements an event source for X displays for the
 *    UNIX version of Tk.
 *
 * Copyright (c) 1995 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * SCCS: @(#) tkUnixEvent.c 1.5 96/02/15 18:55:30
 */

#include "tkInt.h"
#include "tkUnixInt.h"
#include <signal.h>

/*
 * Prototypes for procedures that are referenced only in this file:
 */

static void        DisplayCheckProc _ANSI_ARGS_((ClientData clientData,
                int flags));
static void        DisplaySetupProc _ANSI_ARGS_((ClientData clientData,
                int flags));

/*
 *----------------------------------------------------------------------
 *
 * DisplaySetupProc --
 *
 *    This procedure is part of the event source for UNIX X displays.
 *    It is invoked by Tcl_DoOneEvent before it calls select to check
 *    for events on all displays.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    Tells the notifier which files should be waited for.
 *
 *----------------------------------------------------------------------
 */

static void
DisplaySetupProc(clientData, flags)
    ClientData clientData;        /* Not used. */
    int flags;                /* Flags passed to Tk_DoOneEvent:
                     * if it doesn't include
                     * TCL_WINDOW_EVENTS then we do
                     * nothing. */
{
    TkDisplay *dispPtr;
    static Tcl_Time dontBlock = {0, 0};

    if (!(flags & TCL_WINDOW_EVENTS)) {
    return;
    }

    for (dispPtr = tkDisplayList; dispPtr != NULL; dispPtr = dispPtr->nextPtr) {
    Tcl_File handle;
    XFlush(dispPtr->display);
    if (XQLength(dispPtr->display) > 0) {
        Tcl_SetMaxBlockTime(&dontBlock);
    }
    handle = Tcl_GetFile(
        (ClientData)ConnectionNumber(dispPtr->display), TCL_UNIX_FD);
    Tcl_WatchFile(handle, TCL_READABLE);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * DisplayCheckProc --
 *
 *    This procedure is the second part of the "event source" for
 *    X displays.  It is invoked by Tcl_DoOneEvent after it calls
 *    select (or whatever it uses to wait for events).
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    Makes entries on the Tcl event queue for all the events available
 *    from all the displays.
 *
 *----------------------------------------------------------------------
 */

static void
DisplayCheckProc(clientData, flags)
    ClientData clientData;        /* Not used. */
    int flags;                /* Flags passed to Tk_DoOneEvent:
                     * if it doesn't include
                     * TCL_WINDOW_EVENTS then we do
                     * nothing. */
{
    TkDisplay *dispPtr;
    XEvent event;
    int numFound;

    if (!(flags & TCL_WINDOW_EVENTS)) {
    return;
    }

    for (dispPtr = tkDisplayList; dispPtr != NULL; dispPtr = dispPtr->nextPtr) {
    Tcl_File handle;
    /*
     * Note: we should not need to do a flush of the output queues before
     * calling XEventsQueued because it was done by DisplaySetupProc.
     */

    handle = Tcl_GetFile(
        (ClientData) ConnectionNumber(dispPtr->display), TCL_UNIX_FD);
    if (Tcl_FileReady(handle, TCL_READABLE) != 0) {
        numFound = XEventsQueued(dispPtr->display, QueuedAfterReading);
        if (numFound == 0) {

        /*
         * Things are very tricky if there aren't any events readable
         * at this point (after all, there was supposedly data
         * available on the connection).  A couple of things could
         * have occurred:
         *
         * One possibility is that there were only error events in the
         * input from the server.  If this happens, we should return
         * (we don't want to go to sleep in XNextEvent below, since
         * this would block out other sources of input to the
         * process).
         *
         * Another possibility is that our connection to the server
         * has been closed.  This will not necessarily be detected in
         * XEventsQueued (!!), so if we just return then there will be
         * an infinite loop.  To detect such an error, generate a NoOp
         * protocol request to exercise the connection to the server,
         * then return.  However, must disable SIGPIPE while sending
         * the request, or else the process will die from the signal
         * and won't invoke the X error function to print a nice (?!)
         * message.
         */

        void (*oldHandler)();

        oldHandler = (void (*)()) signal(SIGPIPE, SIG_IGN);
        XNoOp(dispPtr->display);
        XFlush(dispPtr->display);
        (void) signal(SIGPIPE, oldHandler);
        }
    } else {
        numFound = XQLength(dispPtr->display);
    }

    /*
     * Transfer events from the X event queue to the Tk event queue.
     */

    while (numFound > 0) {
        XNextEvent(dispPtr->display, &event);
        Tk_QueueWindowEvent(&event, TCL_QUEUE_TAIL);
        numFound--;
    }
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TkCreateXEventSource --
 *
 *    This procedure is called during Tk initialization to create
 *    the event source for X Window events.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    A new event source is created.
 *
 *----------------------------------------------------------------------
 */

void
TkCreateXEventSource()
{
    static int initialized = 0;

    if (!initialized) {
    Tcl_CreateEventSource(DisplaySetupProc, DisplayCheckProc,
        (ClientData) NULL);
    initialized = 1;
    }
}