sh compatibility fixes

[micropolis] / src / tk / tkplace.c

/* 
 * tkPlace.c --
 *
 *      This file contains code to implement a simple geometry manager
 *      for Tk based on absolute placement or "rubber-sheet" placement.
 *
 * Copyright 1992 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 this copyright
 * notice appears 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/tkPlace.c,v 1.6 92/06/10 08:59:28 ouster Exp $ SPRITE (Berkeley)";
#endif /* not lint */

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

/*
 * Border modes for relative placement:
 *
 * BM_INSIDE:           relative distances computed using area inside
 *                      all borders of master window.
 * BM_OUTSIDE:          relative distances computed using outside area
 *                      that includes all borders of master.
 * BM_IGNORE:           border issues are ignored:  place relative to
 *                      master's actual window size.
 */

typedef enum {BM_INSIDE, BM_OUTSIDE, BM_IGNORE} BorderMode;

/*
 * For each window whose geometry is managed by the placer there is
 * a structure of the following type:
 */

typedef struct Slave {
    Tk_Window tkwin;            /* Tk's token for window. */
    struct Master *masterPtr;   /* Pointer to information for window
                                 * relative to which tkwin is placed.
                                 * This isn't necessarily the logical
                                 * parent of tkwin.  NULL means the
                                 * master was deleted or never assigned. */
    struct Slave *nextPtr;      /* Next in list of windows placed relative
                                 * to same master (NULL for end of list). */

    /*
     * Geometry information for window;  where there are both relative
     * and absolute values for the same attribute (e.g. x and relX) only
     * one of them is actually used, depending on flags.
     */

    int x, y;                   /* X and Y pixel coordinates for tkwin. */
    float relX, relY;           /* X and Y coordinates relative to size of
                                 * master. */
    int width, height;          /* Absolute dimensions for tkwin. */
    float relWidth, relHeight;  /* Dimensions for tkwin relative to size of
                                 * master. */
    Tk_Anchor anchor;           /* Which point on tkwin is placed at the
                                 * given position. */
    BorderMode borderMode;      /* How to treat borders of master window. */
    int flags;                  /* Various flags;  see below for bit
                                 * definitions. */
} Slave;

/*
 * Flag definitions for Slave structures:
 *
 * CHILD_REL_X -                1 means use relX field;  0 means use x.
 * CHILD_REL_Y -                1 means use relY field;  0 means use y;
 * CHILD_WIDTH -                1 means use width field;
 * CHILD_REL_WIDTH -            1 means use relWidth;  if neither this nor
 *                              CHILD_WIDTH is 1, use window's requested
 *                              width.
 * CHILD_HEIGHT -               1 means use height field;
 * CHILD_REL_HEIGHT -           1 means use relHeight;  if neither this nor
 *                              CHILD_HEIGHT is 1, use window's requested
 *                              height.
 */

#define CHILD_REL_X             1
#define CHILD_REL_Y             2
#define CHILD_WIDTH             4
#define CHILD_REL_WIDTH         8
#define CHILD_HEIGHT            0x10
#define CHILD_REL_HEIGHT        0x20

/*
 * For each master window that has a slave managed by the placer there
 * is a structure of the following form:
 */

typedef struct Master {
    Tk_Window tkwin;            /* Tk's token for master window. */
    struct Slave *slavePtr;     /* First in linked list of slaves
                                 * placed relative to this master. */
    int flags;                  /* See below for bit definitions. */
} Master;

/*
 * Flag definitions for masters:
 *
 * PARENT_RECONFIG_PENDING -    1 means that a call to RecomputePlacement
 *                              is already pending via a Do_When_Idle handler.
 */

#define PARENT_RECONFIG_PENDING 1

/*
 * The hash tables below both use Tk_Window tokens as keys.  They map
 * from Tk_Windows to Slave and Master structures for windows, if they
 * exist.
 */

static int initialized = 0;
static Tcl_HashTable masterTable;
static Tcl_HashTable slaveTable;

/*
 * Forward declarations for procedures defined later in this file:
 */

static void             SlaveStructureProc _ANSI_ARGS_((ClientData clientData,
                            XEvent *eventPtr));
static int              ConfigureSlave _ANSI_ARGS_((Tcl_Interp *interp,
                            Slave *slavePtr, int argc, char **argv));
static Slave *          FindSlave _ANSI_ARGS_((Tk_Window tkwin));
static Master *         FindMaster _ANSI_ARGS_((Tk_Window tkwin));
static void             MasterStructureProc _ANSI_ARGS_((ClientData clientData,
                            XEvent *eventPtr));
static void             PlaceRequestProc _ANSI_ARGS_((ClientData clientData,
                            Tk_Window tkwin));
static void             RecomputePlacement _ANSI_ARGS_((ClientData clientData));
static void             UnlinkSlave _ANSI_ARGS_((Slave *slavePtr));
\f
/*
 *--------------------------------------------------------------
 *
 * Tk_PlaceCmd --
 *
 *      This procedure is invoked to process the "place" Tcl
 *      commands.  See the user documentation for details on
 *      what it does.
 *
 * Results:
 *      A standard Tcl result.
 *
 * Side effects:
 *      See the user documentation.
 *
 *--------------------------------------------------------------
 */

int
Tk_PlaceCmd(clientData, interp, argc, argv)
    ClientData clientData;      /* Main window associated with interpreter. */
    Tcl_Interp *interp;         /* Current interpreter. */
    int argc;                   /* Number of arguments. */
    char **argv;                /* Argument strings. */
{
    Tk_Window tkwin;
    Slave *slavePtr;
    Tcl_HashEntry *hPtr;
    int length;
    char c;

    /*
     * Initialize, if that hasn't been done yet.
     */

    if (!initialized) {
        Tcl_InitHashTable(&masterTable, TCL_ONE_WORD_KEYS);
        Tcl_InitHashTable(&slaveTable, TCL_ONE_WORD_KEYS);
        initialized = 1;
    }

    if (argc < 3) {
        Tcl_AppendResult(interp, "wrong # args: should be \"",
                argv[0], " option|pathName args", (char *) NULL);
        return TCL_ERROR;
    }
    c = argv[1][0];
    length = strlen(argv[1]);

    /*
     * Handle special shortcut where window name is first argument.
     */

    if (c == '.') {
        tkwin = Tk_NameToWindow(interp, argv[1], (Tk_Window) clientData);
        if (tkwin == NULL) {
            return TCL_ERROR;
        }
        slavePtr = FindSlave(tkwin);
        return ConfigureSlave(interp, slavePtr, argc-2, argv+2);
    }

    /*
     * Handle more general case of option followed by window name followed
     * by possible additional arguments.
     */

    tkwin = Tk_NameToWindow(interp, argv[2], (Tk_Window) clientData);
    if (tkwin == NULL) {
        return TCL_ERROR;
    }
    if ((c == 'c') && (strncmp(argv[1], "configure", length) == 0)) {
        if (argc < 5) {
            Tcl_AppendResult(interp, "wrong # args: should be \"",
                    argv[0],
                    " configure pathName option value ?option value ...?\"",
                    (char *) NULL);
            return TCL_ERROR;
        }
        slavePtr = FindSlave(tkwin);
        return ConfigureSlave(interp, slavePtr, argc-3, argv+3);
    } else if ((c == 'd') && (strncmp(argv[1], "dependents", length) == 0)) {
        if (argc != 3) {
            Tcl_AppendResult(interp, "wrong # args: should be \"",
                    argv[0], " dependents pathName\"", (char *) NULL);
            return TCL_ERROR;
        }
        hPtr = Tcl_FindHashEntry(&masterTable, (char *) tkwin);
        if (hPtr != NULL) {
            Master *masterPtr;
            masterPtr = (Master *) Tcl_GetHashValue(hPtr);
            for (slavePtr = masterPtr->slavePtr; slavePtr != NULL;
                    slavePtr = slavePtr->nextPtr) {
                Tcl_AppendElement(interp, Tk_PathName(slavePtr->tkwin), 0);
            }
        }
    } else if ((c == 'f') && (strncmp(argv[1], "forget", length) == 0)) {
        if (argc != 3) {
            Tcl_AppendResult(interp, "wrong # args: should be \"",
                    argv[0], " forget pathName\"", (char *) NULL);
            return TCL_ERROR;
        }
        hPtr = Tcl_FindHashEntry(&slaveTable, (char *) tkwin);
        if (hPtr == NULL) {
            return TCL_OK;
        }
        slavePtr = (Slave *) Tcl_GetHashValue(hPtr);
        UnlinkSlave(slavePtr);
        Tcl_DeleteHashEntry(hPtr);
        Tk_DeleteEventHandler(tkwin, StructureNotifyMask, SlaveStructureProc,
                (ClientData) slavePtr);
        Tk_ManageGeometry(tkwin, (Tk_GeometryProc *) NULL, (ClientData) NULL);
        Tk_UnmapWindow(tkwin);
        ckfree((char *) slavePtr);
    } else if ((c == 'i') && (strncmp(argv[1], "info", length) == 0)) {
        char buffer[50];

        if (argc != 3) {
            Tcl_AppendResult(interp, "wrong # args: should be \"",
                    argv[0], " info pathName\"", (char *) NULL);
            return TCL_ERROR;
        }
        hPtr = Tcl_FindHashEntry(&slaveTable, (char *) tkwin);
        if (hPtr == NULL) {
            return TCL_OK;
        }
        slavePtr = (Slave *) Tcl_GetHashValue(hPtr);
        if (slavePtr->flags & CHILD_REL_X) {
            sprintf(buffer, "-relx %.4g", slavePtr->relX);
        } else {
            sprintf(buffer, "-x %d", slavePtr->x);
        }
        Tcl_AppendResult(interp, buffer, (char *) NULL);
        if (slavePtr->flags & CHILD_REL_Y) {
            sprintf(buffer, " -rely %.4g", slavePtr->relY);
        } else {
            sprintf(buffer, " -y %d", slavePtr->y);
        }
        Tcl_AppendResult(interp, buffer, (char *) NULL);
        if (slavePtr->flags & CHILD_REL_WIDTH) {
            sprintf(buffer, " -relwidth %.4g", slavePtr->relWidth);
            Tcl_AppendResult(interp, buffer, (char *) NULL);
        } else if (slavePtr->flags & CHILD_WIDTH) {
            sprintf(buffer, " -width %d", slavePtr->width);
            Tcl_AppendResult(interp, buffer, (char *) NULL);
        }
        if (slavePtr->flags & CHILD_REL_HEIGHT) {
            sprintf(buffer, " -relheight %.4g", slavePtr->relHeight);
            Tcl_AppendResult(interp, buffer, (char *) NULL);
        } else if (slavePtr->flags & CHILD_HEIGHT) {
            sprintf(buffer, " -height %d", slavePtr->height);
            Tcl_AppendResult(interp, buffer, (char *) NULL);
        }
        Tcl_AppendResult(interp, " -anchor ", Tk_NameOfAnchor(slavePtr->anchor),
                (char *) NULL);
        if (slavePtr->borderMode == BM_OUTSIDE) {
            Tcl_AppendResult(interp, " -bordermode outside", (char *) NULL);
        } else if (slavePtr->borderMode == BM_IGNORE) {
            Tcl_AppendResult(interp, " -bordermode ignore", (char *) NULL);
        }
        if ((slavePtr->masterPtr != NULL)
                && (slavePtr->masterPtr->tkwin != Tk_Parent(slavePtr->tkwin))) {
            Tcl_AppendResult(interp, " -in ",
                    Tk_PathName(slavePtr->masterPtr->tkwin), (char *) NULL);
        }
    } else {
        Tcl_AppendResult(interp, "unknown or ambiguous option \"", argv[1],
                "\": must be configure, dependents, forget, or info",
                (char *) NULL);
        return TCL_ERROR;
    }
    return TCL_OK;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * FindSlave --
 *
 *      Given a Tk_Window token, find the Slave structure corresponding
 *      to that token (making a new one if necessary).
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      A new Slave structure may be created.
 *
 *----------------------------------------------------------------------
 */

static Slave *
FindSlave(tkwin)
    Tk_Window tkwin;            /* Token for desired slave. */
{
    Tcl_HashEntry *hPtr;
    register Slave *slavePtr;
    int new;

    hPtr = Tcl_CreateHashEntry(&slaveTable, (char *) tkwin, &new);
    if (new) {
        slavePtr = (Slave *) ckalloc(sizeof(Slave));
        slavePtr->tkwin = tkwin;
        slavePtr->masterPtr = NULL;
        slavePtr->nextPtr = NULL;
        slavePtr->x = slavePtr->y = 0;
        slavePtr->relX = slavePtr->relY = 0.0;
        slavePtr->width = slavePtr->height = 0;
        slavePtr->relWidth = slavePtr->relHeight = 0.0;
        slavePtr->anchor = TK_ANCHOR_NW;
        slavePtr->borderMode = BM_INSIDE;
        slavePtr->flags = 0;
        Tcl_SetHashValue(hPtr, slavePtr);
        Tk_CreateEventHandler(tkwin, StructureNotifyMask, SlaveStructureProc,
                (ClientData) slavePtr);
        Tk_ManageGeometry(tkwin, PlaceRequestProc, (ClientData) slavePtr);
    } else {
        slavePtr = (Slave *) Tcl_GetHashValue(hPtr);
    }
    return slavePtr;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * UnlinkSlave --
 *
 *      This procedure removes a slave window from the chain of slaves
 *      in its master.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The slave list of slavePtr's master changes.
 *
 *----------------------------------------------------------------------
 */

static void
UnlinkSlave(slavePtr)
    Slave *slavePtr;            /* Slave structure to be unlinked. */
{
    register Master *masterPtr;
    register Slave *prevPtr;

    masterPtr = slavePtr->masterPtr;
    if (masterPtr == NULL) {
        return;
    }
    if (masterPtr->slavePtr == slavePtr) {
        masterPtr->slavePtr = slavePtr->nextPtr;
    } else {
        for (prevPtr = masterPtr->slavePtr; ;
                prevPtr = prevPtr->nextPtr) {
            if (prevPtr == NULL) {
                panic("UnlinkSlave couldn't find slave to unlink");
            }
            if (prevPtr->nextPtr == slavePtr) {
                prevPtr->nextPtr = slavePtr->nextPtr;
                break;
            }
        }
    }
    slavePtr->masterPtr = NULL;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * FindMaster --
 *
 *      Given a Tk_Window token, find the Master structure corresponding
 *      to that token (making a new one if necessary).
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      A new Master structure may be created.
 *
 *----------------------------------------------------------------------
 */

static Master *
FindMaster(tkwin)
    Tk_Window tkwin;            /* Token for desired master. */
{
    Tcl_HashEntry *hPtr;
    register Master *masterPtr;
    int new;

    hPtr = Tcl_CreateHashEntry(&masterTable, (char *) tkwin, &new);
    if (new) {
        masterPtr = (Master *) ckalloc(sizeof(Master));
        masterPtr->tkwin = tkwin;
        masterPtr->slavePtr = NULL;
        masterPtr->flags = 0;
        Tcl_SetHashValue(hPtr, masterPtr);
        Tk_CreateEventHandler(masterPtr->tkwin, StructureNotifyMask,
                MasterStructureProc, (ClientData) masterPtr);
    } else {
        masterPtr = (Master *) Tcl_GetHashValue(hPtr);
    }
    return masterPtr;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * ConfigureSlave --
 *
 *      This procedure is called to process an argv/argc list to
 *      reconfigure the placement of a window.
 *
 * Results:
 *      A standard Tcl result.  If an error occurs then a message is
 *      left in interp->result.
 *
 * Side effects:
 *      Information in slavePtr may change, and slavePtr's master is
 *      scheduled for reconfiguration.
 *
 *----------------------------------------------------------------------
 */

static int
ConfigureSlave(interp, slavePtr, argc, argv)
    Tcl_Interp *interp;         /* Used for error reporting. */
    Slave *slavePtr;            /* Pointer to current information
                                 * about slave. */
    int argc;                   /* Number of config arguments. */
    char **argv;                /* String values for arguments. */
{
    register Master *masterPtr;
    int c, length, result;
    double d;

    result = TCL_OK;
    for ( ; argc > 0; argc -= 2, argv += 2) {
        if (argc < 2) {
            Tcl_AppendResult(interp, "extra option \"", argv[0],
                    "\" (option with no value?)", (char *) NULL);
            result = TCL_ERROR;
            goto done;
        }
        length = strlen(argv[0]);
        c = argv[0][1];
        if ((c == 'a') && (strncmp(argv[0], "-anchor", length) == 0)) {
            if (Tk_GetAnchor(interp, argv[1], &slavePtr->anchor) != TCL_OK) {
                result = TCL_ERROR;
                goto done;
            }
        } else if ((c == 'b')
                && (strncmp(argv[0], "-bordermode", length) == 0)) {
            c = argv[1][0];
            length = strlen(argv[1]);
            if ((c == 'i') && (strncmp(argv[1], "ignore", length) == 0)
                    && (length >= 2)) {
                slavePtr->borderMode = BM_IGNORE;
            } else if ((c == 'i') && (strncmp(argv[1], "inside", length) == 0)
                    && (length >= 2)) {
                slavePtr->borderMode = BM_INSIDE;
            } else if ((c == 'o')
                    && (strncmp(argv[1], "outside", length) == 0)) {
                slavePtr->borderMode = BM_OUTSIDE;
            } else {
                Tcl_AppendResult(interp, "bad border mode \"", argv[1],
                        "\": must be ignore, inside, or outside",
                        (char *) NULL);
                result = TCL_ERROR;
                goto done;
            }
        } else if ((c == 'h') && (strncmp(argv[0], "-height", length) == 0)) {
            if (argv[1][0] == 0) {
                slavePtr->flags &= ~(CHILD_REL_HEIGHT|CHILD_HEIGHT);
            } else {
                if (Tk_GetPixels(interp, slavePtr->tkwin, argv[1],
                        &slavePtr->height) != TCL_OK) {
                    result = TCL_ERROR;
                    goto done;
                }
                slavePtr->flags &= ~CHILD_REL_HEIGHT;
                slavePtr->flags |= CHILD_HEIGHT;
            }
        } else if ((c == 'i') && (strncmp(argv[0], "-in", length) == 0)) {
            Tk_Window tkwin;
            Tk_Window ancestor;

            tkwin = Tk_NameToWindow(interp, argv[1], slavePtr->tkwin);
            if (tkwin == NULL) {
                result = TCL_ERROR;
                goto done;
            }

            /*
             * Make sure that the new master is either the logical parent
             * of the slave or a descendant of that window.
             */

            for (ancestor = tkwin; ; ancestor = Tk_Parent(ancestor)) {
                if (ancestor == Tk_Parent(slavePtr->tkwin)) {
                    break;
                }
                if (((Tk_FakeWin *) (ancestor))->flags & TK_TOP_LEVEL) {
                    Tcl_AppendResult(interp, "can't place ",
                            Tk_PathName(slavePtr->tkwin), " relative to ",
                            Tk_PathName(tkwin), (char *) NULL);
                    result = TCL_ERROR;
                    goto done;
                }
            }
            UnlinkSlave(slavePtr);
            slavePtr->masterPtr = FindMaster(tkwin);
            slavePtr->nextPtr = slavePtr->masterPtr->slavePtr;
            slavePtr->masterPtr->slavePtr = slavePtr;
        } else if ((c == 'r') && (strncmp(argv[0], "-relheight", length) == 0)
                && (length >= 5)) {
            if (Tcl_GetDouble(interp, argv[1], &d) != TCL_OK) {
                result = TCL_ERROR;
                goto done;
            }
            slavePtr->relHeight = d;
            slavePtr->flags |= CHILD_REL_HEIGHT;
            slavePtr->flags &= ~CHILD_HEIGHT;
        } else if ((c == 'r') && (strncmp(argv[0], "-relwidth", length) == 0)
                && (length >= 5)) {
            if (Tcl_GetDouble(interp, argv[1], &d) != TCL_OK) {
                result = TCL_ERROR;
                goto done;
            }
            slavePtr->relWidth = d;
            slavePtr->flags |= CHILD_REL_WIDTH;
            slavePtr->flags &= ~CHILD_WIDTH;
        } else if ((c == 'r') && (strncmp(argv[0], "-relx", length) == 0)
                && (length >= 5)) {
            if (Tcl_GetDouble(interp, argv[1], &d) != TCL_OK) {
                result = TCL_ERROR;
                goto done;
            }
            slavePtr->relX = d;
            slavePtr->flags |= CHILD_REL_X;
        } else if ((c == 'r') && (strncmp(argv[0], "-rely", length) == 0)
                && (length >= 5)) {
            if (Tcl_GetDouble(interp, argv[1], &d) != TCL_OK) {
                result = TCL_ERROR;
                goto done;
            }
            slavePtr->relY = d;
            slavePtr->flags |= CHILD_REL_Y;
        } else if ((c == 'w') && (strncmp(argv[0], "-width", length) == 0)) {
            if (argv[1][0] == 0) {
                slavePtr->flags &= ~(CHILD_REL_WIDTH|CHILD_WIDTH);
            } else {
                if (Tk_GetPixels(interp, slavePtr->tkwin, argv[1],
                        &slavePtr->width) != TCL_OK) {
                    result = TCL_ERROR;
                    goto done;
                }
                slavePtr->flags &= ~CHILD_REL_WIDTH;
                slavePtr->flags |= CHILD_WIDTH;
            }
        } else if ((c == 'x') && (strncmp(argv[0], "-x", length) == 0)) {
            if (Tk_GetPixels(interp, slavePtr->tkwin, argv[1],
                    &slavePtr->x) != TCL_OK) {
                result = TCL_ERROR;
                goto done;
            }
            slavePtr->flags &= ~CHILD_REL_X;
        } else if ((c == 'y') && (strncmp(argv[0], "-y", length) == 0)) {
            if (Tk_GetPixels(interp, slavePtr->tkwin, argv[1],
                    &slavePtr->y) != TCL_OK) {
                result = TCL_ERROR;
                goto done;
            }
            slavePtr->flags &= ~CHILD_REL_Y;
        } else {
            Tcl_AppendResult(interp, "unknown or ambiguous option \"",
                    argv[0], "\": must be -anchor, -bordermode, -height, ",
                    "-in, -relheight, -relwidth, -relx, -rely, -width, ",
                    "-x, or -y", (char *) NULL);
            result = TCL_ERROR;
            goto done;
        }
    }

    /*
     * If there's no master specified for this slave, use its Tk_Parent.
     * Then arrange for a placement recalculation in the master.
     */

    done:
    masterPtr = slavePtr->masterPtr;
    if (masterPtr == NULL) {
        masterPtr = FindMaster(Tk_Parent(slavePtr->tkwin));
        slavePtr->masterPtr = masterPtr;
        slavePtr->nextPtr = masterPtr->slavePtr;
        masterPtr->slavePtr = slavePtr;
    }
    if (!(masterPtr->flags & PARENT_RECONFIG_PENDING)) {
        masterPtr->flags |= PARENT_RECONFIG_PENDING;
        Tk_DoWhenIdle(RecomputePlacement, (ClientData) masterPtr);
    }
    return result;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * RecomputePlacement --
 *
 *      This procedure is called as a when-idle handler.  It recomputes
 *      the geometries of all the slaves of a given master.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Windows may change size or shape.
 *
 *----------------------------------------------------------------------
 */

static void
RecomputePlacement(clientData)
    ClientData clientData;      /* Pointer to Master record. */
{
    register Master *masterPtr = (Master *) clientData;
    register Slave *slavePtr;
    Tk_Window ancestor, realMaster;
    int x, y, width, height;
    int masterWidth, masterHeight, masterBW;

    masterPtr->flags &= ~PARENT_RECONFIG_PENDING;

    /*
     * Iterate over all the slaves for the master.  Each slave's
     * geometry can be computed independently of the other slaves.
     */

    for (slavePtr = masterPtr->slavePtr; slavePtr != NULL;
            slavePtr = slavePtr->nextPtr) {
        /*
         * Step 1: compute size and borderwidth of master, taking into
         * account desired border mode.
         */

        masterBW = 0;
        masterWidth = Tk_Width(masterPtr->tkwin);
        masterHeight = Tk_Height(masterPtr->tkwin);
        if (slavePtr->borderMode == BM_INSIDE) {
            masterBW = Tk_InternalBorderWidth(masterPtr->tkwin);
        } else if (slavePtr->borderMode == BM_OUTSIDE) {
            masterBW = -Tk_Changes(masterPtr->tkwin)->border_width;
        }
        masterWidth -= 2*masterBW;
        masterHeight -= 2*masterBW;

        /*
         * Step 2:  compute size of slave (outside dimensions including
         * border) and location of anchor point within master.
         */

        x = slavePtr->x;
        if (slavePtr->flags & CHILD_REL_X) {
            x = (slavePtr->relX*masterWidth) +
                ((slavePtr->relX > 0) ? 0.5 : -0.5);
        }
        x += masterBW;
        y = slavePtr->y;
        if (slavePtr->flags & CHILD_REL_Y) {
            y = (slavePtr->relY*masterHeight) +
                ((slavePtr->relY > 0) ? 0.5 : -0.5);
        }
        y += masterBW;
        if (slavePtr->flags & CHILD_REL_WIDTH) {
            width = (slavePtr->relWidth*masterWidth) + 0.5;
        } else if (slavePtr->flags & CHILD_WIDTH) {
            width = slavePtr->width;
        } else {
            width = Tk_ReqWidth(slavePtr->tkwin)
                    + 2*Tk_Changes(slavePtr->tkwin)->border_width;
        }
        if (slavePtr->flags & CHILD_REL_HEIGHT) {
            height = (slavePtr->relHeight*masterHeight) + 0.5;
        } else if (slavePtr->flags & CHILD_HEIGHT) {
            height = slavePtr->height;
        } else {
            height = Tk_ReqHeight(slavePtr->tkwin)
                    + 2*Tk_Changes(slavePtr->tkwin)->border_width;
        }

        /*
         * Step 3: adjust the x and y positions so that the desired
         * anchor point on the slave appears at that position.  Also
         * adjust for the border mode and master's border.
         */

        switch (slavePtr->anchor) {
            case TK_ANCHOR_N:
                x -= width/2;
                break;
            case TK_ANCHOR_NE:
                x -= width;
                break;
            case TK_ANCHOR_E:
                x -= width;
                y -= height/2;
                break;
            case TK_ANCHOR_SE:
                x -= width;
                y -= height;
                break;
            case TK_ANCHOR_S:
                x -= width/2;
                y -= height;
                break;
            case TK_ANCHOR_SW:
                y -= height;
                break;
            case TK_ANCHOR_W:
                y -= height/2;
                break;
            case TK_ANCHOR_NW:
                break;
            case TK_ANCHOR_CENTER:
                x -= width/2;
                y -= height/2;
                break;
        }

        /*
         * Step 4: if masterPtr isn't actually the X master of slavePtr,
         * then translate the x and y coordinates back into the coordinate
         * system of masterPtr.
         */

        for (ancestor = masterPtr->tkwin,
                realMaster = Tk_Parent(slavePtr->tkwin);
                ancestor != realMaster; ancestor = Tk_Parent(ancestor)) {
            x += Tk_X(ancestor) + Tk_Changes(ancestor)->border_width;
            y += Tk_Y(ancestor) + Tk_Changes(ancestor)->border_width;
        }

        /*
         * Step 5: adjust width and height again to reflect inside dimensions
         * of window rather than outside.  Also make sure that the width and
         * height aren't zero.
         */

        width -= 2*Tk_Changes(slavePtr->tkwin)->border_width;
        height -= 2*Tk_Changes(slavePtr->tkwin)->border_width;
        if (width <= 0) {
            width = 1;
        }
        if (height <= 0) {
            height = 1;
        }

        /*
         * Step 6: see if the window's size or location has changed;  if
         * so then tell X to reconfigure it.
         */

        if ((x != Tk_X(slavePtr->tkwin))
                || (y != Tk_Y(slavePtr->tkwin))
                || (width != Tk_Width(slavePtr->tkwin))
                || (height != Tk_Height(slavePtr->tkwin))) {
            Tk_MoveResizeWindow(slavePtr->tkwin, x, y,
                    (unsigned int) width, (unsigned int) height);
        }
        Tk_MapWindow(slavePtr->tkwin);
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * MasterStructureProc --
 *
 *      This procedure is invoked by the Tk event handler when
 *      StructureNotify events occur for a master window.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Structures get cleaned up if the window was deleted.  If the
 *      window was resized then slave geometries get recomputed.
 *
 *----------------------------------------------------------------------
 */

static void
MasterStructureProc(clientData, eventPtr)
    ClientData clientData;      /* Pointer to Master structure for window
                                 * referred to by eventPtr. */
    XEvent *eventPtr;           /* Describes what just happened. */
{
    register Master *masterPtr = (Master *) clientData;
    register Slave *slavePtr, *nextPtr;

    if (eventPtr->type == ConfigureNotify) {
        if ((masterPtr->slavePtr != NULL)
                && !(masterPtr->flags & PARENT_RECONFIG_PENDING)) {
            masterPtr->flags |= PARENT_RECONFIG_PENDING;
            Tk_DoWhenIdle(RecomputePlacement, (ClientData) masterPtr);
        }
    } else if (eventPtr->type == DestroyNotify) {
        for (slavePtr = masterPtr->slavePtr; slavePtr != NULL;
                slavePtr = nextPtr) {
            slavePtr->masterPtr = NULL;
            nextPtr = slavePtr->nextPtr;
            slavePtr->nextPtr = NULL;
        }
        Tcl_DeleteHashEntry(Tcl_FindHashEntry(&masterTable,
                (char *) masterPtr->tkwin));
        if (masterPtr->flags & PARENT_RECONFIG_PENDING) {
            Tk_CancelIdleCall(RecomputePlacement, (ClientData) masterPtr);
        }
        masterPtr->tkwin = NULL;
        ckfree((char *) masterPtr);
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * SlaveStructureProc --
 *
 *      This procedure is invoked by the Tk event handler when
 *      StructureNotify events occur for a slave window.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Structures get cleaned up if the window was deleted.
 *
 *----------------------------------------------------------------------
 */

static void
SlaveStructureProc(clientData, eventPtr)
    ClientData clientData;      /* Pointer to Slave structure for window
                                 * referred to by eventPtr. */
    XEvent *eventPtr;           /* Describes what just happened. */
{
    register Slave *slavePtr = (Slave *) clientData;

    if (eventPtr->type == DestroyNotify) {
        UnlinkSlave(slavePtr);
        Tcl_DeleteHashEntry(Tcl_FindHashEntry(&slaveTable,
                (char *) slavePtr->tkwin));
        ckfree((char *) slavePtr);
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * PlaceRequestProc --
 *
 *      This procedure is invoked by Tk whenever a slave managed by us
 *      changes its requested geometry.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The window will get relayed out, if its requested size has
 *      anything to do with its actual size.
 *
 *----------------------------------------------------------------------
 */

        /* ARGSUSED */
static void
PlaceRequestProc(clientData, tkwin)
    ClientData clientData;              /* Pointer to our record for slave. */
    Tk_Window tkwin;                    /* Window that changed its desired
                                         * size. */
{
    Slave *slavePtr = (Slave *) clientData;
    Master *masterPtr;

    if (((slavePtr->flags & (CHILD_WIDTH|CHILD_REL_WIDTH)) != 0)
            && ((slavePtr->flags & (CHILD_HEIGHT|CHILD_REL_HEIGHT)) != 0)) {
        return;
    }
    masterPtr = slavePtr->masterPtr;
    if (masterPtr == NULL) {
        return;
    }
    if (!(masterPtr->flags & PARENT_RECONFIG_PENDING)) {
        masterPtr->flags |= PARENT_RECONFIG_PENDING;
        Tk_DoWhenIdle(RecomputePlacement, (ClientData) masterPtr);
    }
}