shared_source/c_tk_base_7_5_w_mods/tkscale.c

/* $Header$ */

/* 
 * tkScale.c --
 *
 *      This module implements a scale widgets for the Tk toolkit.
 *      A scale displays a slider that can be adjusted to change a
 *      value;  it also displays numeric labels and a textual label,
 *      if desired.
 *      
 *      The modifications to use floating-point values are based on
 *      an implementation by Paul Mackerras.  The -variable option
 *      is due to Henning Schulzrinne.  All of these are used with
 *      permission.
 *
 * Copyright (c) 1990-1994 The Regents of the University of California.
 * Copyright (c) 1994-1997 Sun Microsystems, Inc.
 * Copyright (c) 1998-2000 by Scriptics Corporation.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tkscale.c,v 1.1.1.1 2001/06/13 05:07:45 dtashley Exp $
 */

#include "tkPort.h"
#include "default.h"
#include "tkInt.h"
#include "tclMath.h"
#include "tkScale.h"

/*
 * The following table defines the legal values for the -orient option.
 * It is used together with the "enum orient" declaration in tkScale.h.
 */

static char *orientStrings[] = {
    "horizontal", "vertical", (char *) NULL
};

/*
 * The following table defines the legal values for the -state option.
 * It is used together with the "enum state" declaration in tkScale.h.
 */

static char *stateStrings[] = {
    "active", "disabled", "normal", (char *) NULL
};

static Tk_OptionSpec optionSpecs[] = {
    {TK_OPTION_BORDER, "-activebackground", "activeBackground", "Foreground",
        DEF_SCALE_ACTIVE_BG_COLOR, -1, Tk_Offset(TkScale, activeBorder),
        0, (ClientData) DEF_SCALE_ACTIVE_BG_MONO, 0},
    {TK_OPTION_BORDER, "-background", "background", "Background",
        DEF_SCALE_BG_COLOR, -1, Tk_Offset(TkScale, bgBorder),
        0, (ClientData) DEF_SCALE_BG_MONO, 0},
    {TK_OPTION_DOUBLE, "-bigincrement", "bigIncrement", "BigIncrement",
        DEF_SCALE_BIG_INCREMENT, -1, Tk_Offset(TkScale, bigIncrement), 
        0, 0, 0},
    {TK_OPTION_SYNONYM, "-bd", (char *) NULL, (char *) NULL,
        (char *) NULL, 0, -1, 0, (ClientData) "-borderwidth", 0},
    {TK_OPTION_SYNONYM, "-bg", (char *) NULL, (char *) NULL,
        (char *) NULL, 0, -1, 0, (ClientData) "-background", 0},
    {TK_OPTION_PIXELS, "-borderwidth", "borderWidth", "BorderWidth",
        DEF_SCALE_BORDER_WIDTH, -1, Tk_Offset(TkScale, borderWidth), 
        0, 0, 0},
    {TK_OPTION_STRING, "-command", "command", "Command",
        DEF_SCALE_COMMAND, -1, Tk_Offset(TkScale, command),
        TK_OPTION_NULL_OK, 0, 0},
    {TK_OPTION_CURSOR, "-cursor", "cursor", "Cursor",
        DEF_SCALE_CURSOR, -1, Tk_Offset(TkScale, cursor),
        TK_OPTION_NULL_OK, 0, 0},
    {TK_OPTION_INT, "-digits", "digits", "Digits", 
        DEF_SCALE_DIGITS, -1, Tk_Offset(TkScale, digits), 
        0, 0, 0},
    {TK_OPTION_SYNONYM, "-fg", "foreground", (char *) NULL,
        (char *) NULL, 0, -1, 0, (ClientData) "-foreground", 0},
    {TK_OPTION_FONT, "-font", "font", "Font",
        DEF_SCALE_FONT, -1, Tk_Offset(TkScale, tkfont), 0, 0, 0},
    {TK_OPTION_COLOR, "-foreground", "foreground", "Foreground",
        DEF_SCALE_FG_COLOR, -1, Tk_Offset(TkScale, textColorPtr), 0, 
        (ClientData) DEF_SCALE_FG_MONO, 0},
    {TK_OPTION_DOUBLE, "-from", "from", "From", DEF_SCALE_FROM, -1, 
        Tk_Offset(TkScale, fromValue), 0, 0, 0},
    {TK_OPTION_BORDER, "-highlightbackground", "highlightBackground",
        "HighlightBackground", DEF_SCALE_HIGHLIGHT_BG_COLOR,
        -1, Tk_Offset(TkScale, highlightBorder), 
        0, (ClientData) DEF_SCALE_HIGHLIGHT_BG_MONO, 0},
    {TK_OPTION_COLOR, "-highlightcolor", "highlightColor", "HighlightColor",
        DEF_SCALE_HIGHLIGHT, -1, Tk_Offset(TkScale, highlightColorPtr),
        0, 0, 0},
    {TK_OPTION_PIXELS, "-highlightthickness", "highlightThickness",
        "HighlightThickness", DEF_SCALE_HIGHLIGHT_WIDTH, -1, 
        Tk_Offset(TkScale, highlightWidth), 0, 0, 0},
    {TK_OPTION_STRING, "-label", "label", "Label",
        DEF_SCALE_LABEL, -1, Tk_Offset(TkScale, label),
        TK_OPTION_NULL_OK, 0, 0},
    {TK_OPTION_PIXELS, "-length", "length", "Length",
        DEF_SCALE_LENGTH, -1, Tk_Offset(TkScale, length), 0, 0, 0},
    {TK_OPTION_STRING_TABLE, "-orient", "orient", "Orient",
        DEF_SCALE_ORIENT, -1, Tk_Offset(TkScale, orient), 
        0, (ClientData) orientStrings, 0},
    {TK_OPTION_RELIEF, "-relief", "relief", "Relief",
        DEF_SCALE_RELIEF, -1, Tk_Offset(TkScale, relief), 0, 0, 0},
    {TK_OPTION_INT, "-repeatdelay", "repeatDelay", "RepeatDelay",
        DEF_SCALE_REPEAT_DELAY, -1, Tk_Offset(TkScale, repeatDelay),
        0, 0, 0},
    {TK_OPTION_INT, "-repeatinterval", "repeatInterval", "RepeatInterval",
        DEF_SCALE_REPEAT_INTERVAL, -1, Tk_Offset(TkScale, repeatInterval),
        0, 0, 0},
    {TK_OPTION_DOUBLE, "-resolution", "resolution", "Resolution",
        DEF_SCALE_RESOLUTION, -1, Tk_Offset(TkScale, resolution),
        0, 0, 0},
    {TK_OPTION_BOOLEAN, "-showvalue", "showValue", "ShowValue",
        DEF_SCALE_SHOW_VALUE, -1, Tk_Offset(TkScale, showValue),
        0, 0, 0},
    {TK_OPTION_PIXELS, "-sliderlength", "sliderLength", "SliderLength",
        DEF_SCALE_SLIDER_LENGTH, -1, Tk_Offset(TkScale, sliderLength),
        0, 0, 0},
    {TK_OPTION_RELIEF, "-sliderrelief", "sliderRelief", "SliderRelief",
        DEF_SCALE_SLIDER_RELIEF, -1, Tk_Offset(TkScale, sliderRelief), 
        0, 0, 0},
    {TK_OPTION_STRING_TABLE, "-state", "state", "State",
        DEF_SCALE_STATE, -1, Tk_Offset(TkScale, state), 
        0, (ClientData) stateStrings, 0},
    {TK_OPTION_STRING, "-takefocus", "takeFocus", "TakeFocus",
        DEF_SCALE_TAKE_FOCUS, Tk_Offset(TkScale, takeFocusPtr), -1,
        TK_OPTION_NULL_OK, 0, 0},
    {TK_OPTION_DOUBLE, "-tickinterval", "tickInterval", "TickInterval",
        DEF_SCALE_TICK_INTERVAL, -1, Tk_Offset(TkScale, tickInterval),
        0, 0, 0},
    {TK_OPTION_DOUBLE, "-to", "to", "To",
        DEF_SCALE_TO, -1, Tk_Offset(TkScale, toValue), 0, 0, 0},
    {TK_OPTION_COLOR, "-troughcolor", "troughColor", "Background",
        DEF_SCALE_TROUGH_COLOR, -1, Tk_Offset(TkScale, troughColorPtr),
        0, (ClientData) DEF_SCALE_TROUGH_MONO, 0},
    {TK_OPTION_STRING, "-variable", "variable", "Variable",
        DEF_SCALE_VARIABLE, Tk_Offset(TkScale, varNamePtr), -1,
        TK_OPTION_NULL_OK, 0, 0},
    {TK_OPTION_PIXELS, "-width", "width", "Width",
        DEF_SCALE_WIDTH, -1, Tk_Offset(TkScale, width), 0, 0, 0},
    {TK_OPTION_END, (char *) NULL, (char *) NULL, (char *) NULL,
        (char *) NULL, 0, -1, 0, 0, 0}
};

/*
 * The following tables define the scale widget commands and map the 
 * indexes into the string tables into a single enumerated type used 
 * to dispatch the scale widget command.
 */

static char *commandNames[] = {
    "cget", "configure", "coords", "get", "identify", "set", (char *) NULL
};

enum command {
    COMMAND_CGET, COMMAND_CONFIGURE, COMMAND_COORDS, COMMAND_GET,
    COMMAND_IDENTIFY, COMMAND_SET
};

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

static void             ComputeFormat _ANSI_ARGS_((TkScale *scalePtr));
static void             ComputeScaleGeometry _ANSI_ARGS_((TkScale *scalePtr));
static int              ConfigureScale _ANSI_ARGS_((Tcl_Interp *interp,
                            TkScale *scalePtr, int objc,
                            Tcl_Obj *CONST objv[]));
static void             DestroyScale _ANSI_ARGS_((char *memPtr));
static void             ScaleCmdDeletedProc _ANSI_ARGS_((
                            ClientData clientData));
static void             ScaleEventProc _ANSI_ARGS_((ClientData clientData,
                            XEvent *eventPtr));
static char *           ScaleVarProc _ANSI_ARGS_((ClientData clientData,
                            Tcl_Interp *interp, char *name1, char *name2,
                            int flags));
static int              ScaleWidgetObjCmd _ANSI_ARGS_((ClientData clientData,
                            Tcl_Interp *interp, int objc, 
                            Tcl_Obj *CONST objv[]));
static void             ScaleWorldChanged _ANSI_ARGS_((
                            ClientData instanceData));
static void             ScaleSetVariable _ANSI_ARGS_((TkScale *scalePtr));

/*
 * The structure below defines scale class behavior by means of procedures
 * that can be invoked from generic window code.
 */

static TkClassProcs scaleClass = {
    NULL,                       /* createProc. */
    ScaleWorldChanged,          /* geometryProc. */
    NULL                        /* modalProc. */
};


/*
 *--------------------------------------------------------------
 *
 * Tk_ScaleObjCmd --
 *
 *      This procedure is invoked to process the "scale" Tcl
 *      command.  See the user documentation for details on what
 *      it does.
 *
 * Results:
 *      A standard Tcl result.
 *
 * Side effects:
 *      See the user documentation.
 *
 *--------------------------------------------------------------
 */

int
Tk_ScaleObjCmd(clientData, interp, objc, objv)
    ClientData clientData;      /* Either NULL or pointer to option table. */
    Tcl_Interp *interp;         /* Current interpreter. */
    int objc;                   /* Number of arguments. */
    Tcl_Obj *CONST objv[];      /* Argument values. */
{
    register TkScale *scalePtr;
    Tk_OptionTable optionTable;
    Tk_Window tkwin;

    optionTable = (Tk_OptionTable) clientData;
    if (optionTable == NULL) {
        Tcl_CmdInfo info;
        char *name;

        /*
         * We haven't created the option table for this widget class
         * yet.  Do it now and save the table as the clientData for
         * the command, so we'll have access to it in future
         * invocations of the command.
         */

        optionTable = Tk_CreateOptionTable(interp, optionSpecs);
        name = Tcl_GetString(objv[0]);
        Tcl_GetCommandInfo(interp, name, &info);
        info.objClientData = (ClientData) optionTable;
        Tcl_SetCommandInfo(interp, name, &info);
    }

    if (objc < 2) {
        Tcl_WrongNumArgs(interp, 1, objv, "pathName ?options?");
        return TCL_ERROR;
    }

    tkwin = Tk_CreateWindowFromPath(interp, Tk_MainWindow(interp),
            Tcl_GetString(objv[1]), (char *) NULL);
    if (tkwin == NULL) {
        return TCL_ERROR;
    }

    Tk_SetClass(tkwin, "Scale");
    scalePtr = TkpCreateScale(tkwin);

    /*
     * Initialize fields that won't be initialized by ConfigureScale,
     * or which ConfigureScale expects to have reasonable values
     * (e.g. resource pointers).
     */

    scalePtr->tkwin             = tkwin;
    scalePtr->display           = Tk_Display(tkwin);
    scalePtr->interp            = interp;
    scalePtr->widgetCmd         = Tcl_CreateObjCommand(interp,
            Tk_PathName(scalePtr->tkwin), ScaleWidgetObjCmd,
            (ClientData) scalePtr, ScaleCmdDeletedProc);
    scalePtr->optionTable       = optionTable;
    scalePtr->orient            = ORIENT_VERTICAL;
    scalePtr->width             = 0;
    scalePtr->length            = 0;
    scalePtr->value             = 0.0;
    scalePtr->varNamePtr        = NULL;
    scalePtr->fromValue         = 0.0;
    scalePtr->toValue           = 0.0;
    scalePtr->tickInterval      = 0.0;
    scalePtr->resolution        = 1.0;
    scalePtr->digits            = 0;
    scalePtr->bigIncrement      = 0.0;
    scalePtr->command           = NULL;
    scalePtr->repeatDelay       = 0;
    scalePtr->repeatInterval    = 0;
    scalePtr->label             = NULL;
    scalePtr->labelLength       = 0;
    scalePtr->state             = STATE_NORMAL;
    scalePtr->borderWidth       = 0;
    scalePtr->bgBorder          = NULL;
    scalePtr->activeBorder      = NULL;
    scalePtr->sliderRelief      = TK_RELIEF_RAISED;
    scalePtr->troughColorPtr    = NULL;
    scalePtr->troughGC          = None;
    scalePtr->copyGC            = None;
    scalePtr->tkfont            = NULL;
    scalePtr->textColorPtr      = NULL;
    scalePtr->textGC            = None;
    scalePtr->relief            = TK_RELIEF_FLAT;
    scalePtr->highlightWidth    = 0;
    scalePtr->highlightBorder   = NULL;
    scalePtr->highlightColorPtr = NULL;
    scalePtr->inset             = 0;
    scalePtr->sliderLength      = 0;
    scalePtr->showValue         = 0;
    scalePtr->horizLabelY       = 0;
    scalePtr->horizValueY       = 0;
    scalePtr->horizTroughY      = 0;
    scalePtr->horizTickY        = 0;
    scalePtr->vertTickRightX    = 0;
    scalePtr->vertValueRightX   = 0;
    scalePtr->vertTroughX       = 0;
    scalePtr->vertLabelX        = 0;
    scalePtr->fontHeight        = 0;
    scalePtr->cursor            = None;
    scalePtr->takeFocusPtr      = NULL;
    scalePtr->flags             = NEVER_SET;

    TkSetClassProcs(scalePtr->tkwin, &scaleClass, (ClientData) scalePtr);
    Tk_CreateEventHandler(scalePtr->tkwin,
            ExposureMask|StructureNotifyMask|FocusChangeMask,
            ScaleEventProc, (ClientData) scalePtr);

    if ((Tk_InitOptions(interp, (char *) scalePtr, optionTable, tkwin)
            != TCL_OK) ||
            (ConfigureScale(interp, scalePtr, objc - 2, objv + 2) != TCL_OK)) {
        Tk_DestroyWindow(scalePtr->tkwin);
        return TCL_ERROR;
    }

    Tcl_SetResult(interp, Tk_PathName(scalePtr->tkwin), TCL_STATIC);
    return TCL_OK;
}

/*
 *--------------------------------------------------------------
 *
 * ScaleWidgetObjCmd --
 *
 *      This procedure is invoked to process the Tcl command
 *      that corresponds to a widget managed by this module.
 *      See the user documentation for details on what it does.
 *
 * Results:
 *      A standard Tcl result.
 *
 * Side effects:
 *      See the user documentation.
 *
 *--------------------------------------------------------------
 */

static int
ScaleWidgetObjCmd(clientData, interp, objc, objv)
    ClientData clientData;              /* Information about scale
                                         * widget. */
    Tcl_Interp *interp;                 /* Current interpreter. */
    int objc;                           /* Number of arguments. */
    Tcl_Obj *CONST objv[];              /* Argument strings. */
{
    TkScale *scalePtr = (TkScale *) clientData;
    Tcl_Obj *objPtr;
    int index, result;

    if (objc < 2) {
        Tcl_WrongNumArgs(interp, 1, objv, "option ?arg arg ...?");
        return TCL_ERROR;
    }
    result = Tcl_GetIndexFromObj(interp, objv[1], commandNames,
            "option", 0, &index);
    if (result != TCL_OK) {
        return result;
    }
    Tcl_Preserve((ClientData) scalePtr);

    switch (index) {
        case COMMAND_CGET: {
            if (objc != 3) {
                Tcl_WrongNumArgs(interp, 1, objv, "cget option");
                goto error;
            }
            objPtr = Tk_GetOptionValue(interp, (char *) scalePtr,
                    scalePtr->optionTable, objv[2], scalePtr->tkwin);
            if (objPtr == NULL) {
                 goto error;
            } else {
                Tcl_SetObjResult(interp, objPtr);
            }
            break;
        }
        case COMMAND_CONFIGURE: {
            if (objc <= 3) {
                objPtr = Tk_GetOptionInfo(interp, (char *) scalePtr,
                        scalePtr->optionTable,
                        (objc == 3) ? objv[2] : (Tcl_Obj *) NULL,
                        scalePtr->tkwin);
                if (objPtr == NULL) {
                    goto error;
                } else {
                    Tcl_SetObjResult(interp, objPtr);
                }
            } else {
                result = ConfigureScale(interp, scalePtr, objc-2, objv+2);
            }
            break;
        }
        case COMMAND_COORDS: {
            int x, y ;
            double value;
            char buf[TCL_INTEGER_SPACE * 2];

            if ((objc != 2) && (objc != 3)) {
                Tcl_WrongNumArgs(interp, 1, objv, "coords ?value?");
                goto error;
            }
            if (objc == 3) {
                if (Tcl_GetDoubleFromObj(interp, objv[2], &value) 
                        != TCL_OK) {
                    goto error;
                }
            } else {
                value = scalePtr->value;
            }
            if (scalePtr->orient == ORIENT_VERTICAL) {
                x = scalePtr->vertTroughX + scalePtr->width/2
                        + scalePtr->borderWidth;
                y = TkScaleValueToPixel(scalePtr, value);
            } else {
                x = TkScaleValueToPixel(scalePtr, value);
                y = scalePtr->horizTroughY + scalePtr->width/2
                        + scalePtr->borderWidth;
            }
            sprintf(buf, "%d %d", x, y);
            Tcl_SetResult(interp, buf, TCL_VOLATILE);
            break;
        }
        case COMMAND_GET: {
            double value;
            int x, y;
            char buf[TCL_DOUBLE_SPACE];

            if ((objc != 2) && (objc != 4)) {
                Tcl_WrongNumArgs(interp, 1, objv, "get ?x y?");
                goto error;
            }
            if (objc == 2) {
                value = scalePtr->value;
            } else {
                if ((Tcl_GetIntFromObj(interp, objv[2], &x) != TCL_OK)
                        || (Tcl_GetIntFromObj(interp, objv[3], &y) 
                        != TCL_OK)) {
                    goto error;
                }
                value = TkScalePixelToValue(scalePtr, x, y);
            }
            sprintf(buf, scalePtr->format, value);
            Tcl_SetResult(interp, buf, TCL_VOLATILE);
            break;
        }
        case COMMAND_IDENTIFY: {
            int x, y, thing;

            if (objc != 4) {
                Tcl_WrongNumArgs(interp, 1, objv, "identify x y");
                goto error;
            }
            if ((Tcl_GetIntFromObj(interp, objv[2], &x) != TCL_OK)
                    || (Tcl_GetIntFromObj(interp, objv[3], &y) != TCL_OK)) {
                goto error;
            }
            thing = TkpScaleElement(scalePtr, x,y);
            switch (thing) {
                case TROUGH1:
                    Tcl_SetResult(interp, "trough1", TCL_STATIC);
                    break;
                case SLIDER:
                    Tcl_SetResult(interp, "slider", TCL_STATIC);
                    break;
                case TROUGH2:
                    Tcl_SetResult(interp, "trough2", TCL_STATIC);
                    break;
            }
            break;
        }
        case COMMAND_SET: {
            double value;

            if (objc != 3) {
                Tcl_WrongNumArgs(interp, 1, objv, "set value");
                goto error;
            }
            if (Tcl_GetDoubleFromObj(interp, objv[2], &value) != TCL_OK) {
                goto error;
            }
            if (scalePtr->state != STATE_DISABLED) {
              TkScaleSetValue(scalePtr, value, 1, 1);
            }
            break;
        } 
    }
    Tcl_Release((ClientData) scalePtr);
    return result;

    error:
    Tcl_Release((ClientData) scalePtr);
    return TCL_ERROR;
}

/*
 *----------------------------------------------------------------------
 *
 * DestroyScale --
 *
 *      This procedure is invoked by Tcl_EventuallyFree or Tcl_Release
 *      to clean up the internal structure of a button at a safe time
 *      (when no-one is using it anymore).
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Everything associated with the scale is freed up.
 *
 *----------------------------------------------------------------------
 */

static void
DestroyScale(memPtr)
    char *memPtr;       /* Info about scale widget. */
{
    register TkScale *scalePtr = (TkScale *) memPtr;

    scalePtr->flags |= SCALE_DELETED;

    Tcl_DeleteCommandFromToken(scalePtr->interp, scalePtr->widgetCmd);
    if (scalePtr->flags & REDRAW_PENDING) {
        Tcl_CancelIdleCall(TkpDisplayScale, (ClientData) scalePtr);
    }

    /*
     * Free up all the stuff that requires special handling, then
     * let Tk_FreeOptions handle all the standard option-related
     * stuff.
     */

    if (scalePtr->varNamePtr != NULL) {
        Tcl_UntraceVar(scalePtr->interp, Tcl_GetString(scalePtr->varNamePtr),
                TCL_GLOBAL_ONLY|TCL_TRACE_WRITES|TCL_TRACE_UNSETS,
                ScaleVarProc, (ClientData) scalePtr);
    }
    if (scalePtr->troughGC != None) {
        Tk_FreeGC(scalePtr->display, scalePtr->troughGC);
    }
    if (scalePtr->copyGC != None) {
        Tk_FreeGC(scalePtr->display, scalePtr->copyGC);
    }
    if (scalePtr->textGC != None) {
        Tk_FreeGC(scalePtr->display, scalePtr->textGC);
    }
    Tk_FreeConfigOptions((char *) scalePtr, scalePtr->optionTable,
            scalePtr->tkwin);
    scalePtr->tkwin = NULL;
    TkpDestroyScale(scalePtr);
}

/*
 *----------------------------------------------------------------------
 *
 * ConfigureScale --
 *
 *      This procedure is called to process an argv/argc list, plus
 *      the Tk option database, in order to configure (or
 *      reconfigure) a scale widget.
 *
 * Results:
 *      The return value is a standard Tcl result.  If TCL_ERROR is
 *      returned, then the interp's result contains an error message.
 *
 * Side effects:
 *      Configuration information, such as colors, border width,
 *      etc. get set for scalePtr;  old resources get freed,
 *      if there were any.
 *
 *----------------------------------------------------------------------
 */

static int
ConfigureScale(interp, scalePtr, objc, objv)
    Tcl_Interp *interp;         /* Used for error reporting. */
    register TkScale *scalePtr; /* Information about widget;  may or may
                                 * not already have values for some fields. */
    int objc;                   /* Number of valid entries in objv. */
    Tcl_Obj *CONST objv[];      /* Argument values. */
{
    Tk_SavedOptions savedOptions;
    Tcl_Obj *errorResult = NULL;
    int error;
    double oldValue = scalePtr->value;

    /*
     * Eliminate any existing trace on a variable monitored by the scale.
     */

    if (scalePtr->varNamePtr != NULL) {
        Tcl_UntraceVar(interp, Tcl_GetString(scalePtr->varNamePtr),
                TCL_GLOBAL_ONLY|TCL_TRACE_WRITES|TCL_TRACE_UNSETS,
                ScaleVarProc, (ClientData) scalePtr);
    }

    for (error = 0; error <= 1; error++) {
        if (!error) {
            /*
             * First pass: set options to new values.
             */

            if (Tk_SetOptions(interp, (char *) scalePtr,
                    scalePtr->optionTable, objc, objv,
                    scalePtr->tkwin, &savedOptions, (int *) NULL) != TCL_OK) {
                continue;
            }
        } else {
            /*
             * Second pass: restore options to old values.
             */

            errorResult = Tcl_GetObjResult(interp);
            Tcl_IncrRefCount(errorResult);
            Tk_RestoreSavedOptions(&savedOptions);
        }

        /*
         * If the scale is tied to the value of a variable, then set 
         * the scale's value from the value of the variable, if it exists
         * and it holds a valid double value.
         */

        if (scalePtr->varNamePtr != NULL) {
            double value;
            Tcl_Obj *valuePtr;

            valuePtr = Tcl_ObjGetVar2(interp, scalePtr->varNamePtr, NULL,
                    TCL_GLOBAL_ONLY);
            if ((valuePtr != NULL) &&
                    (Tcl_GetDoubleFromObj(NULL, valuePtr, &value) == TCL_OK)) {
                scalePtr->value = TkRoundToResolution(scalePtr, value);
            }
        }

        /*
         * Several options need special processing, such as parsing the
         * orientation and creating GCs.
         */

        scalePtr->fromValue = TkRoundToResolution(scalePtr, 
                scalePtr->fromValue);
        scalePtr->toValue = TkRoundToResolution(scalePtr, scalePtr->toValue);
        scalePtr->tickInterval = TkRoundToResolution(scalePtr,
                scalePtr->tickInterval);

        /*
         * Make sure that the tick interval has the right sign so that
         * addition moves from fromValue to toValue.
         */

        if ((scalePtr->tickInterval < 0)
                ^ ((scalePtr->toValue - scalePtr->fromValue) <  0)) {
          scalePtr->tickInterval = -scalePtr->tickInterval;
        }

        ComputeFormat(scalePtr);

        scalePtr->labelLength = scalePtr->label ? strlen(scalePtr->label) : 0;

        Tk_SetBackgroundFromBorder(scalePtr->tkwin, scalePtr->bgBorder);

        if (scalePtr->highlightWidth < 0) {
            scalePtr->highlightWidth = 0;
        }
        scalePtr->inset = scalePtr->highlightWidth + scalePtr->borderWidth;
        break;
    }
    if (!error) {
        Tk_FreeSavedOptions(&savedOptions);
    }

    /*
     * Set the scale value to itself;  all this does is to make sure
     * that the scale's value is within the new acceptable range for
     * the scale.  We don't set the var here because we need to make
     * special checks for possibly changed varNamePtr.
     */

    TkScaleSetValue(scalePtr, scalePtr->value, 0, 1);

    /*
     * Reestablish the variable trace, if it is needed.
     */

    if (scalePtr->varNamePtr != NULL) {
        Tcl_Obj *valuePtr;

        /*
         * Set the associated variable only when the new value differs
         * from the current value, or the variable doesn't yet exist
         */
        valuePtr = Tcl_ObjGetVar2(interp, scalePtr->varNamePtr, NULL,
                TCL_GLOBAL_ONLY);
        if ((valuePtr == NULL) || (scalePtr->value != oldValue)
                || (Tcl_GetDoubleFromObj(NULL, valuePtr, &oldValue) != TCL_OK)
                || (scalePtr->value != oldValue)) {
            ScaleSetVariable(scalePtr);
        }
        Tcl_TraceVar(interp, Tcl_GetString(scalePtr->varNamePtr),
                TCL_GLOBAL_ONLY|TCL_TRACE_WRITES|TCL_TRACE_UNSETS,
                ScaleVarProc, (ClientData) scalePtr);
    }

    ScaleWorldChanged((ClientData) scalePtr);
    if (error) {
        Tcl_SetObjResult(interp, errorResult);
        Tcl_DecrRefCount(errorResult);
        return TCL_ERROR;
    } else {
        return TCL_OK;
    }
}

/*
 *---------------------------------------------------------------------------
 *
 * ScaleWorldChanged --
 *
 *      This procedure is called when the world has changed in some
 *      way and the widget needs to recompute all its graphics contexts
 *      and determine its new geometry.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Scale will be relayed out and redisplayed.
 *
 *---------------------------------------------------------------------------
 */
 
static void
ScaleWorldChanged(instanceData)
    ClientData instanceData;    /* Information about widget. */
{
    XGCValues gcValues;
    GC gc;
    TkScale *scalePtr;

    scalePtr = (TkScale *) instanceData;

    gcValues.foreground = scalePtr->troughColorPtr->pixel;
    gc = Tk_GetGC(scalePtr->tkwin, GCForeground, &gcValues);
    if (scalePtr->troughGC != None) {
        Tk_FreeGC(scalePtr->display, scalePtr->troughGC);
    }
    scalePtr->troughGC = gc;

    gcValues.font = Tk_FontId(scalePtr->tkfont);
    gcValues.foreground = scalePtr->textColorPtr->pixel;
    gc = Tk_GetGC(scalePtr->tkwin, GCForeground | GCFont, &gcValues);
    if (scalePtr->textGC != None) {
        Tk_FreeGC(scalePtr->display, scalePtr->textGC);
    }
    scalePtr->textGC = gc;

    if (scalePtr->copyGC == None) {
        gcValues.graphics_exposures = False;
        scalePtr->copyGC = Tk_GetGC(scalePtr->tkwin, GCGraphicsExposures,
            &gcValues);
    }
    scalePtr->inset = scalePtr->highlightWidth + scalePtr->borderWidth;

    /*
     * Recompute display-related information, and let the geometry
     * manager know how much space is needed now.
     */

    ComputeScaleGeometry(scalePtr);

    TkEventuallyRedrawScale(scalePtr, REDRAW_ALL);
}

/*
 *----------------------------------------------------------------------
 *
 * ComputeFormat --
 *
 *      This procedure is invoked to recompute the "format" field
 *      of a scale's widget record, which determines how the value
 *      of the scale is converted to a string.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The format field of scalePtr is modified.
 *
 *----------------------------------------------------------------------
 */

static void
ComputeFormat(scalePtr)
    TkScale *scalePtr;                  /* Information about scale widget. */
{
    double maxValue, x;
    int mostSigDigit, numDigits, leastSigDigit, afterDecimal;
    int eDigits, fDigits;

    /*
     * Compute the displacement from the decimal of the most significant
     * digit required for any number in the scale's range.
     */

    maxValue = fabs(scalePtr->fromValue);
    x = fabs(scalePtr->toValue);
    if (x > maxValue) {
        maxValue = x;
    }
    if (maxValue == 0) {
        maxValue = 1;
    }
    mostSigDigit = (int) floor(log10(maxValue));

    /*
     * If the number of significant digits wasn't specified explicitly,
     * compute it. It's the difference between the most significant
     * digit needed to represent any number on the scale and the
     * most significant digit of the smallest difference between
     * numbers on the scale.  In other words, display enough digits so
     * that at least one digit will be different between any two adjacent
     * positions of the scale.
     */

    numDigits = scalePtr->digits;
    if (numDigits <= 0) {
        if  (scalePtr->resolution > 0) {
            /*
             * A resolution was specified for the scale, so just use it.
             */

            leastSigDigit = (int) floor(log10(scalePtr->resolution));
        } else {
            /*
             * No resolution was specified, so compute the difference
             * in value between adjacent pixels and use it for the least
             * significant digit.
             */

            x = fabs(scalePtr->fromValue - scalePtr->toValue);
            if (scalePtr->length > 0) {
                x /= scalePtr->length;
            }
            if (x > 0){
                leastSigDigit = (int) floor(log10(x));
            } else {
                leastSigDigit = 0;
            }
        }
        numDigits = mostSigDigit - leastSigDigit + 1;
        if (numDigits < 1) {
            numDigits = 1;
        }
    }

    /*
     * Compute the number of characters required using "e" format and
     * "f" format, and then choose whichever one takes fewer characters.
     */

    eDigits = numDigits + 4;
    if (numDigits > 1) {
        eDigits++;                      /* Decimal point. */
    }
    afterDecimal = numDigits - mostSigDigit - 1;
    if (afterDecimal < 0) {
        afterDecimal = 0;
    }
    fDigits = (mostSigDigit >= 0) ? mostSigDigit + afterDecimal : afterDecimal;
    if (afterDecimal > 0) {
        fDigits++;                      /* Decimal point. */
    }
    if (mostSigDigit < 0) {
        fDigits++;                      /* Zero to left of decimal point. */
    }
    if (fDigits <= eDigits) {
        sprintf(scalePtr->format, "%%.%df", afterDecimal);
    } else {
        sprintf(scalePtr->format, "%%.%de", numDigits-1);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * ComputeScaleGeometry --
 *
 *      This procedure is called to compute various geometrical
 *      information for a scale, such as where various things get
 *      displayed.  It's called when the window is reconfigured.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Display-related numbers get changed in *scalePtr.  The
 *      geometry manager gets told about the window's preferred size.
 *
 *----------------------------------------------------------------------
 */

static void
ComputeScaleGeometry(scalePtr)
    register TkScale *scalePtr;         /* Information about widget. */
{
    char valueString[PRINT_CHARS];
    int tmp, valuePixels, x, y, extraSpace;
    Tk_FontMetrics fm;

    Tk_GetFontMetrics(scalePtr->tkfont, &fm);
    scalePtr->fontHeight = fm.linespace + SPACING;

    /*
     * Horizontal scales are simpler than vertical ones because
     * all sizes are the same (the height of a line of text);
     * handle them first and then quit.
     */

    if (scalePtr->orient == ORIENT_HORIZONTAL) {
        y = scalePtr->inset;
        extraSpace = 0;
        if (scalePtr->labelLength != 0) {
            scalePtr->horizLabelY = y + SPACING;
            y += scalePtr->fontHeight;
            extraSpace = SPACING;
        }
        if (scalePtr->showValue) {
            scalePtr->horizValueY = y + SPACING;
            y += scalePtr->fontHeight;
            extraSpace = SPACING;
        } else {
            scalePtr->horizValueY = y;
        }
        y += extraSpace;
        scalePtr->horizTroughY = y;
        y += scalePtr->width + 2*scalePtr->borderWidth;
        if (scalePtr->tickInterval != 0) {
            scalePtr->horizTickY = y + SPACING;
            y += scalePtr->fontHeight + SPACING;
        }
        Tk_GeometryRequest(scalePtr->tkwin,
                scalePtr->length + 2*scalePtr->inset, y + scalePtr->inset);
        Tk_SetInternalBorder(scalePtr->tkwin, scalePtr->inset);
        return;
    }

    /*
     * Vertical scale:  compute the amount of space needed to display
     * the scales value by formatting strings for the two end points;
     * use whichever length is longer.
     */

    sprintf(valueString, scalePtr->format, scalePtr->fromValue);
    valuePixels = Tk_TextWidth(scalePtr->tkfont, valueString, -1);

    sprintf(valueString, scalePtr->format, scalePtr->toValue);
    tmp = Tk_TextWidth(scalePtr->tkfont, valueString, -1);
    if (valuePixels < tmp) {
        valuePixels = tmp;
    }

    /*
     * Assign x-locations to the elements of the scale, working from
     * left to right.
     */

    x = scalePtr->inset;
    if ((scalePtr->tickInterval != 0) && (scalePtr->showValue)) {
        scalePtr->vertTickRightX = x + SPACING + valuePixels;
        scalePtr->vertValueRightX = scalePtr->vertTickRightX + valuePixels
                + fm.ascent/2;
        x = scalePtr->vertValueRightX + SPACING;
    } else if (scalePtr->tickInterval != 0) {
        scalePtr->vertTickRightX = x + SPACING + valuePixels;
        scalePtr->vertValueRightX = scalePtr->vertTickRightX;
        x = scalePtr->vertTickRightX + SPACING;
    } else if (scalePtr->showValue) {
        scalePtr->vertTickRightX = x;
        scalePtr->vertValueRightX = x + SPACING + valuePixels;
        x = scalePtr->vertValueRightX + SPACING;
    } else {
        scalePtr->vertTickRightX = x;
        scalePtr->vertValueRightX = x;
    }
    scalePtr->vertTroughX = x;
    x += 2*scalePtr->borderWidth + scalePtr->width;
    if (scalePtr->labelLength == 0) {
        scalePtr->vertLabelX = 0;
    } else {
        scalePtr->vertLabelX = x + fm.ascent/2;
        x = scalePtr->vertLabelX + fm.ascent/2
            + Tk_TextWidth(scalePtr->tkfont, scalePtr->label,
                    scalePtr->labelLength);
    }
    Tk_GeometryRequest(scalePtr->tkwin, x + scalePtr->inset,
            scalePtr->length + 2*scalePtr->inset);
    Tk_SetInternalBorder(scalePtr->tkwin, scalePtr->inset);
}

/*
 *--------------------------------------------------------------
 *
 * ScaleEventProc --
 *
 *      This procedure is invoked by the Tk dispatcher for various
 *      events on scales.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      When the window gets deleted, internal structures get
 *      cleaned up.  When it gets exposed, it is redisplayed.
 *
 *--------------------------------------------------------------
 */

static void
ScaleEventProc(clientData, eventPtr)
    ClientData clientData;      /* Information about window. */
    XEvent *eventPtr;           /* Information about event. */
{
    TkScale *scalePtr = (TkScale *) clientData;

    if ((eventPtr->type == Expose) && (eventPtr->xexpose.count == 0)) {
        TkEventuallyRedrawScale(scalePtr, REDRAW_ALL);
    } else if (eventPtr->type == DestroyNotify) {
        DestroyScale((char *) clientData);
    } else if (eventPtr->type == ConfigureNotify) {
        ComputeScaleGeometry(scalePtr);
        TkEventuallyRedrawScale(scalePtr, REDRAW_ALL);
    } else if (eventPtr->type == FocusIn) {
        if (eventPtr->xfocus.detail != NotifyInferior) {
            scalePtr->flags |= GOT_FOCUS;
            if (scalePtr->highlightWidth > 0) {
                TkEventuallyRedrawScale(scalePtr, REDRAW_ALL);
            }
        }
    } else if (eventPtr->type == FocusOut) {
        if (eventPtr->xfocus.detail != NotifyInferior) {
            scalePtr->flags &= ~GOT_FOCUS;
            if (scalePtr->highlightWidth > 0) {
                TkEventuallyRedrawScale(scalePtr, REDRAW_ALL);
            }
        }
    }
}

/*
 *----------------------------------------------------------------------
 *
 * ScaleCmdDeletedProc --
 *
 *      This procedure is invoked when a widget command is deleted.  If
 *      the widget isn't already in the process of being destroyed,
 *      this command destroys it.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The widget is destroyed.
 *
 *----------------------------------------------------------------------
 */

static void
ScaleCmdDeletedProc(clientData)
    ClientData clientData;      /* Pointer to widget record for widget. */
{
    TkScale *scalePtr = (TkScale *) clientData;
    Tk_Window tkwin = scalePtr->tkwin;

    /*
     * This procedure could be invoked either because the window was
     * destroyed and the command was then deleted (in which case tkwin
     * is NULL) or because the command was deleted, and then this procedure
     * destroys the widget.
     */

    if (!(scalePtr->flags & SCALE_DELETED)) {
        scalePtr->flags |= SCALE_DELETED;
        Tk_DestroyWindow(tkwin);
    }
}

/*
 *--------------------------------------------------------------
 *
 * TkEventuallyRedrawScale --
 *
 *      Arrange for part or all of a scale widget to redrawn at
 *      the next convenient time in the future.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      If "what" is REDRAW_SLIDER then just the slider and the
 *      value readout will be redrawn;  if "what" is REDRAW_ALL
 *      then the entire widget will be redrawn.
 *
 *--------------------------------------------------------------
 */

void
TkEventuallyRedrawScale(scalePtr, what)
    register TkScale *scalePtr; /* Information about widget. */
    int what;                   /* What to redraw:  REDRAW_SLIDER
                                 * or REDRAW_ALL. */
{
    if ((what == 0) || (scalePtr->tkwin == NULL)
            || !Tk_IsMapped(scalePtr->tkwin)) {
        return;
    }
    if (!(scalePtr->flags & REDRAW_PENDING)) {
        scalePtr->flags |= REDRAW_PENDING;
        Tcl_DoWhenIdle(TkpDisplayScale, (ClientData) scalePtr);
    }
    scalePtr->flags |= what;
}

/*
 *--------------------------------------------------------------
 *
 * TkRoundToResolution --
 *
 *      Round a given floating-point value to the nearest multiple
 *      of the scale's resolution.
 *
 * Results:
 *      The return value is the rounded result.
 *
 * Side effects:
 *      None.
 *
 *--------------------------------------------------------------
 */

double
TkRoundToResolution(scalePtr, value)
    TkScale *scalePtr;          /* Information about scale widget. */
    double value;               /* Value to round. */
{
    double rem, new, tick;

    if (scalePtr->resolution <= 0) {
        return value;
    }
    tick = floor(value/scalePtr->resolution);
    new = scalePtr->resolution * tick;
    rem = value - new;
    if (rem < 0) {
        if (rem <= -scalePtr->resolution/2) {
            new = (tick - 1.0) * scalePtr->resolution;
        }
    } else {
        if (rem >= scalePtr->resolution/2) {
            new = (tick + 1.0) * scalePtr->resolution;
        }
    }
    return new;
}

/*
 *----------------------------------------------------------------------
 *
 * ScaleVarProc --
 *
 *      This procedure is invoked by Tcl whenever someone modifies a
 *      variable associated with a scale widget.
 *
 * Results:
 *      NULL is always returned.
 *
 * Side effects:
 *      The value displayed in the scale will change to match the
 *      variable's new value.  If the variable has a bogus value then
 *      it is reset to the value of the scale.
 *
 *----------------------------------------------------------------------
 */

    /* ARGSUSED */
static char *
ScaleVarProc(clientData, interp, name1, name2, flags)
    ClientData clientData;      /* Information about button. */
    Tcl_Interp *interp;         /* Interpreter containing variable. */
    char *name1;                /* Name of variable. */
    char *name2;                /* Second part of variable name. */
    int flags;                  /* Information about what happened. */
{
    register TkScale *scalePtr = (TkScale *) clientData;
    char *resultStr;
    double value;
    Tcl_Obj *valuePtr;
    int result;

    /*
     * If the variable is unset, then immediately recreate it unless
     * the whole interpreter is going away.
     */

    if (flags & TCL_TRACE_UNSETS) {
        if ((flags & TCL_TRACE_DESTROYED) && !(flags & TCL_INTERP_DESTROYED)) {
            Tcl_TraceVar(interp, Tcl_GetString(scalePtr->varNamePtr),
                    TCL_GLOBAL_ONLY|TCL_TRACE_WRITES|TCL_TRACE_UNSETS,
                    ScaleVarProc, clientData);
            scalePtr->flags |= NEVER_SET;
            TkScaleSetValue(scalePtr, scalePtr->value, 1, 0);
        }
        return (char *) NULL;
    }

    /*
     * If we came here because we updated the variable (in TkScaleSetValue),
     * then ignore the trace.  Otherwise update the scale with the value
     * of the variable.
     */

    if (scalePtr->flags & SETTING_VAR) {
        return (char *) NULL;
    }
    resultStr = NULL;
    valuePtr = Tcl_ObjGetVar2(interp, scalePtr->varNamePtr, NULL, 
            TCL_GLOBAL_ONLY);
    result = Tcl_GetDoubleFromObj(interp, valuePtr, &value);
    if (result != TCL_OK) {
        resultStr = "can't assign non-numeric value to scale variable";
        ScaleSetVariable(scalePtr);
    } else {
        scalePtr->value = TkRoundToResolution(scalePtr, value);

        /*
         * This code is a bit tricky because it sets the scale's value before
         * calling TkScaleSetValue.  This way, TkScaleSetValue won't bother 
         * to set the variable again or to invoke the -command.  However, it
         * also won't redisplay the scale, so we have to ask for that
         * explicitly.
         */

        TkScaleSetValue(scalePtr, scalePtr->value, 1, 0);
    }
    TkEventuallyRedrawScale(scalePtr, REDRAW_SLIDER);

    return resultStr;
}

/*
 *--------------------------------------------------------------
 *
 * TkScaleSetValue --
 *
 *      This procedure changes the value of a scale and invokes
 *      a Tcl command to reflect the current position of a scale
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      A Tcl command is invoked, and an additional error-processing
 *      command may also be invoked.  The scale's slider is redrawn.
 *
 *--------------------------------------------------------------
 */

void
TkScaleSetValue(scalePtr, value, setVar, invokeCommand)
    register TkScale *scalePtr; /* Info about widget. */
    double value;               /* New value for scale.  Gets adjusted
                                 * if it's off the scale. */
    int setVar;                 /* Non-zero means reflect new value through
                                 * to associated variable, if any. */
    int invokeCommand;          /* Non-zero means invoked -command option
                                 * to notify of new value, 0 means don't. */
{
    value = TkRoundToResolution(scalePtr, value);
    if ((value < scalePtr->fromValue)
            ^ (scalePtr->toValue < scalePtr->fromValue)) {
        value = scalePtr->fromValue;
    }
    if ((value > scalePtr->toValue)
            ^ (scalePtr->toValue < scalePtr->fromValue)) {
        value = scalePtr->toValue;
    }
    if (scalePtr->flags & NEVER_SET) {
        scalePtr->flags &= ~NEVER_SET;
    } else if (scalePtr->value == value) {
        return;
    }
    scalePtr->value = value;
    if (invokeCommand) {
        scalePtr->flags |= INVOKE_COMMAND;
    }
    TkEventuallyRedrawScale(scalePtr, REDRAW_SLIDER);

    if (setVar && scalePtr->varNamePtr) {
        ScaleSetVariable(scalePtr);
    }
}

/*
 *--------------------------------------------------------------
 *
 * ScaleSetVariable --
 *
 *      This procedure sets the variable associated with a scale, if any.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Other write traces on the variable will trigger.
 *
 *--------------------------------------------------------------
 */

static void
ScaleSetVariable(scalePtr)
    register TkScale *scalePtr; /* Info about widget. */
{
    if (scalePtr->varNamePtr != NULL) {
        char string[PRINT_CHARS];
        sprintf(string, scalePtr->format, scalePtr->value);
        scalePtr->flags |= SETTING_VAR;
        Tcl_ObjSetVar2(scalePtr->interp, scalePtr->varNamePtr, NULL,
                Tcl_NewStringObj(string, -1), TCL_GLOBAL_ONLY);
        scalePtr->flags &= ~SETTING_VAR;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TkScalePixelToValue --
 *
 *      Given a pixel within a scale window, return the scale
 *      reading corresponding to that pixel.
 *
 * Results:
 *      A double-precision scale reading.  If the value is outside
 *      the legal range for the scale then it's rounded to the nearest
 *      end of the scale.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

double
TkScalePixelToValue(scalePtr, x, y)
    register TkScale *scalePtr;         /* Information about widget. */
    int x, y;                           /* Coordinates of point within
                                         * window. */
{
    double value, pixelRange;

    if (scalePtr->orient == ORIENT_VERTICAL) {
        pixelRange = Tk_Height(scalePtr->tkwin) - scalePtr->sliderLength
                - 2*scalePtr->inset - 2*scalePtr->borderWidth;
        value = y;
    } else {
        pixelRange = Tk_Width(scalePtr->tkwin) - scalePtr->sliderLength
                - 2*scalePtr->inset - 2*scalePtr->borderWidth;
        value = x;
    }

    if (pixelRange <= 0) {
        /*
         * Not enough room for the slider to actually slide:  just return
         * the scale's current value.
         */

        return scalePtr->value;
    }
    value -= scalePtr->sliderLength/2 + scalePtr->inset
                + scalePtr->borderWidth;
    value /= pixelRange;
    if (value < 0) {
        value = 0;
    }
    if (value > 1) {
        value = 1;
    }
    value = scalePtr->fromValue +
                value * (scalePtr->toValue - scalePtr->fromValue);
    return TkRoundToResolution(scalePtr, value);
}

/*
 *----------------------------------------------------------------------
 *
 * TkScaleValueToPixel --
 *
 *      Given a reading of the scale, return the x-coordinate or
 *      y-coordinate corresponding to that reading, depending on
 *      whether the scale is vertical or horizontal, respectively.
 *
 * Results:
 *      An integer value giving the pixel location corresponding
 *      to reading.  The value is restricted to lie within the
 *      defined range for the scale.
 *
 * Side effects:
 *      None.
 *
 *----------------------------------------------------------------------
 */

int
TkScaleValueToPixel(scalePtr, value)
    register TkScale *scalePtr;         /* Information about widget. */
    double value;                       /* Reading of the widget. */
{
    int y, pixelRange;
    double valueRange;

    valueRange = scalePtr->toValue - scalePtr->fromValue;
    pixelRange = ((scalePtr->orient == ORIENT_VERTICAL)
            ? Tk_Height(scalePtr->tkwin) : Tk_Width(scalePtr->tkwin))
        - scalePtr->sliderLength - 2*scalePtr->inset - 2*scalePtr->borderWidth;
    if (valueRange == 0) {
        y = 0;
    } else {
        y = (int) ((value - scalePtr->fromValue) * pixelRange
                  / valueRange + 0.5);
        if (y < 0) {
            y = 0;
        } else if (y > pixelRange) {
            y = pixelRange;
        }
    }
    y += scalePtr->sliderLength/2 + scalePtr->inset + scalePtr->borderWidth;
    return y;
}

/* End of tkscale.c */