[micropolis] / src / tk / tkatom.c

/* 
 * tkAtom.c --
 *
 *      This file manages a cache of X Atoms in order to avoid
 *      interactions with the X server.  It's much like the Xmu
 *      routines, except it has a cleaner interface (caller
 *      doesn't have to provide permanent storage for atom names,
 *      for example).
 *
 * Copyright 1990 Regents of the University of California.
 * Permission to use, copy, modify, and distribute this
 * software and its documentation for any purpose and without
 * fee is hereby granted, provided that the above copyright
 * notice appear in all copies.  The University of California
 * makes no representations about the suitability of this
 * software for any purpose.  It is provided "as is" without
 * express or implied warranty.
 */

#ifndef lint
static char rcsid[] = "$Header: /user6/ouster/wish/RCS/tkAtom.c,v 1.6 92/05/07 09:51:06 ouster Exp $ SPRITE (Berkeley)";
#endif

#include "tkconfig.h"
#include "tkint.h"

/*
 * Forward references to procedures defined in this file:
 */

static void     AtomInit _ANSI_ARGS_((TkDisplay *dispPtr));
\f
/*
 *--------------------------------------------------------------
 *
 * Tk_InternAtom --
 *
 *      Given a string, produce the equivalent X atom.  This
 *      procedure is equivalent to XInternAtom, except that it
 *      keeps a local cache of atoms.  Once a name is known,
 *      the server need not be contacted again for that name.
 *
 * Results:
 *      The return value is the Atom corresponding to name.
 *
 * Side effects:
 *      A new entry may be added to the local atom cache.
 *
 *--------------------------------------------------------------
 */

Atom
Tk_InternAtom(tkwin, name)
    Tk_Window tkwin;            /* Window token;  map name to atom
                                 * for this window's display. */
    char *name;                 /* Name to turn into atom. */
{
    register TkDisplay *dispPtr;
    register Tcl_HashEntry *hPtr;
    int new;

    dispPtr = ((TkWindow *) tkwin)->dispPtr;
    if (!dispPtr->atomInit) {
        AtomInit(dispPtr);
    }

    hPtr = Tcl_CreateHashEntry(&dispPtr->nameTable, name, &new);
    if (new) {
        Tcl_HashEntry *hPtr2;
        Atom atom;

        atom = XInternAtom(dispPtr->display, name, False);
        Tcl_SetHashValue(hPtr, atom);
        hPtr2 = Tcl_CreateHashEntry(&dispPtr->atomTable, (char *) atom,
                &new);
        Tcl_SetHashValue(hPtr2, Tcl_GetHashKey(&dispPtr->nameTable, hPtr));
    }
    return (Atom) Tcl_GetHashValue(hPtr);
}
\f
/*
 *--------------------------------------------------------------
 *
 * Tk_GetAtomName --
 *
 *      This procedure is equivalent to XGetAtomName except that
 *      it uses the local atom cache to avoid contacting the
 *      server.
 *
 * Results:
 *      The return value is a character string corresponding to
 *      the atom given by "atom".  This string's storage space
 *      is static:  it need not be freed by the caller, and should
 *      not be modified by the caller.  If "atom" doesn't exist
 *      on tkwin's display, then the string "?bad atom?" is returned.
 *
 * Side effects:
 *      None.
 *
 *--------------------------------------------------------------
 */

char *
Tk_GetAtomName(tkwin, atom)
    Tk_Window tkwin;            /* Window token;  map atom to name
                                 * relative to this window's
                                 * display. */
    Atom atom;                  /* Atom whose name is wanted. */
{
    register TkDisplay *dispPtr;
    register Tcl_HashEntry *hPtr;

    dispPtr = ((TkWindow *) tkwin)->dispPtr;
    if (!dispPtr->atomInit) {
        AtomInit(dispPtr);
    }

    hPtr = Tcl_FindHashEntry(&dispPtr->atomTable, (char *) atom);
    if (hPtr == NULL) {
        char *name;
        Tk_ErrorHandler handler;
        int new;

        handler= Tk_CreateErrorHandler(dispPtr->display, BadAtom,
                -1, -1, (int (*)()) NULL, (ClientData) NULL);
        name = XGetAtomName(dispPtr->display, atom);
        if (name == NULL) {
            name = "?bad atom?";
        }
        Tk_DeleteErrorHandler(handler);
        hPtr = Tcl_CreateHashEntry(&dispPtr->nameTable, (char *) name,
                &new);
        Tcl_SetHashValue(hPtr, atom);
        name = Tcl_GetHashKey(&dispPtr->nameTable, hPtr);
        hPtr = Tcl_CreateHashEntry(&dispPtr->atomTable, (char *) atom,
                &new);
        Tcl_SetHashValue(hPtr, name);
    }
    return (char *) Tcl_GetHashValue(hPtr);
}
\f
/*
 *--------------------------------------------------------------
 *
 * AtomInit --
 *
 *      Initialize atom-related information for a display.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Tables get initialized, etc. etc..
 *
 *--------------------------------------------------------------
 */

static void
AtomInit(dispPtr)
    register TkDisplay *dispPtr;        /* Display to initialize. */
{
    dispPtr->atomInit = 1;
    Tcl_InitHashTable(&dispPtr->nameTable, TCL_STRING_KEYS);
    Tcl_InitHashTable(&dispPtr->atomTable, TCL_ONE_WORD_KEYS);
}