[micropolis] / src / tk / tkscrbar.c

/* 
 * tkScrollbar.c --
 *
 *      This module implements a scrollbar widgets for the Tk
 *      toolkit.  A scrollbar displays a slider and two arrows;
 *      mouse clicks on features within the scrollbar cause
 *      scrolling commands to be invoked.
 *
 * Copyright 1990-1992 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 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/tkScrollbar.c,v 1.35 92/05/22 16:57:27 ouster Exp $ SPRITE (Berkeley)";
#endif

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

/*
 * A data structure of the following type is kept for each scrollbar
 * widget managed by this file:
 */

typedef struct {
    Tk_Window tkwin;            /* Window that embodies the scrollbar.  NULL
                                 * means that the window has been destroyed
                                 * but the data structures haven't yet been
                                 * cleaned up.*/
    Tcl_Interp *interp;         /* Interpreter associated with scrollbar. */
    Tk_Uid orientUid;           /* Orientation for window ("vertical" or
                                 * "horizontal"). */
    int vertical;               /* Non-zero means vertical orientation
                                 * requested, zero means horizontal. */
    int width;                  /* Desired narrow dimension of scrollbar,
                                 * in pixels. */
    char *command;              /* Command prefix to use when invoking
                                 * scrolling commands.  NULL means don't
                                 * invoke commands.  Malloc'ed. */
    int commandSize;            /* Number of non-NULL bytes in command. */
    int repeatDelay;            /* How long to wait before auto-repeating
                                 * on scrolling actions (in ms). */
    int repeatInterval;         /* Interval between autorepeats (in ms). */

    /*
     * Information used when displaying widget:
     */

    int borderWidth;            /* Width of 3-D borders. */
    Tk_3DBorder bgBorder;       /* Used for drawing background. */
    Tk_3DBorder fgBorder;       /* For drawing foreground shapes. */
    Tk_3DBorder activeBorder;   /* For drawing foreground shapes when
                                 * active (i.e. when mouse is positioned
                                 * over element).  NULL means use fgBorder. */
    GC copyGC;                  /* Used for copying from pixmap onto screen. */
    int relief;                 /* Indicates whether window as a whole is
                                 * raised, sunken, or flat. */
    int offset;                 /* Zero if relief is TK_RELIEF_FLAT,
                                 * borderWidth otherwise.   Indicates how
                                 * much interior stuff must be offset from
                                 * outside edges to leave room for border. */
    int arrowLength;            /* Length of arrows along long dimension of
                                 * scrollbar.  Recomputed on window size
                                 * changes. */
    int sliderFirst;            /* Pixel coordinate of top or left edge
                                 * of slider area, including border. */
    int sliderLast;             /* Coordinate of pixel just after bottom
                                 * or right edge of slider area, including
                                 * border. */
    int mouseField;             /* Indicates which scrollbar element is
                                 * under mouse (e.g. TOP_ARROW;  see below
                                 * for possible values). */
    int pressField;             /* Field in which button was pressed, or -1
                                 * if no button is down. */
    int pressPos;               /* Position of mouse when button was
                                 * pressed (y for vertical scrollbar, x
                                 * for horizontal). */
    int pressFirstUnit;         /* Value of "firstUnit" when mouse button
                                 * was pressed. */

    /*
     * Information describing the application related to the scrollbar.
     * This information is provided by the application by invoking the
     * "set" widget command.
     */

    int totalUnits;             /* Total dimension of application, in
                                 * units. */
    int windowUnits;            /* Maximum number of units that can
                                 * be displayed in the window at
                                 * once. */
    int firstUnit;              /* Number of last unit visible in
                                 * application's window. */
    int lastUnit;               /* Index of last unit visible in window. */

    /*
     * Miscellaneous information:
     */

    Cursor cursor;              /* Current cursor for window, or None. */
    Tk_TimerToken autoRepeat;   /* Token for auto-repeat that's
                                 * currently in progress.  NULL means no
                                 * auto-repeat in progress. */
    int flags;                  /* Various flags;  see below for
                                 * definitions. */
} Scrollbar;

/*
 * Legal values for "mouseField" field of Scrollbar structures.  These
 * are also the return values from the ScrollbarPosition procedure.
 */

#define TOP_ARROW       1
#define TOP_GAP         2
#define SLIDER          3
#define BOTTOM_GAP      4
#define BOTTOM_ARROW    5
#define OUTSIDE         6

/*
 * Flag bits for scrollbars:
 * 
 * REDRAW_PENDING:              Non-zero means a DoWhenIdle handler
 *                              has already been queued to redraw
 *                              this window.
 */

#define REDRAW_PENDING          1

/*
 * Information used for argv parsing.
 */


static Tk_ConfigSpec configSpecs[] = {
    {TK_CONFIG_BORDER, "-activeforeground", "activeForeground", "Background",
        DEF_SCROLLBAR_ACTIVE_FG_COLOR, Tk_Offset(Scrollbar, activeBorder),
        TK_CONFIG_COLOR_ONLY},
    {TK_CONFIG_BORDER, "-activeforeground", "activeForeground", "Background",
        DEF_SCROLLBAR_ACTIVE_FG_MONO, Tk_Offset(Scrollbar, activeBorder),
        TK_CONFIG_MONO_ONLY},
    {TK_CONFIG_BORDER, "-background", "background", "Background",
        DEF_SCROLLBAR_BG_COLOR, Tk_Offset(Scrollbar, bgBorder),
        TK_CONFIG_COLOR_ONLY},
    {TK_CONFIG_BORDER, "-background", "background", "Background",
        DEF_SCROLLBAR_BG_MONO, Tk_Offset(Scrollbar, bgBorder),
        TK_CONFIG_MONO_ONLY},
    {TK_CONFIG_SYNONYM, "-bd", "borderWidth", (char *) NULL,
        (char *) NULL, 0, 0},
    {TK_CONFIG_SYNONYM, "-bg", "background", (char *) NULL,
        (char *) NULL, 0, 0},
    {TK_CONFIG_PIXELS, "-borderwidth", "borderWidth", "BorderWidth",
        DEF_SCROLLBAR_BORDER_WIDTH, Tk_Offset(Scrollbar, borderWidth), 0},
    {TK_CONFIG_STRING, "-command", "command", "Command",
        DEF_SCROLLBAR_COMMAND, Tk_Offset(Scrollbar, command), 0},
    {TK_CONFIG_ACTIVE_CURSOR, "-cursor", "cursor", "Cursor",
        DEF_SCROLLBAR_CURSOR, Tk_Offset(Scrollbar, cursor), TK_CONFIG_NULL_OK},
    {TK_CONFIG_SYNONYM, "-fg", "foreground", (char *) NULL,
        (char *) NULL, 0, 0},
    {TK_CONFIG_BORDER, "-foreground", "foreground", "Foreground",
        DEF_SCROLLBAR_FG_COLOR, Tk_Offset(Scrollbar, fgBorder),
        TK_CONFIG_COLOR_ONLY},
    {TK_CONFIG_BORDER, "-foreground", "foreground", "Foreground",
        DEF_SCROLLBAR_FG_MONO, Tk_Offset(Scrollbar, fgBorder),
        TK_CONFIG_MONO_ONLY},
    {TK_CONFIG_UID, "-orient", "orient", "Orient",
        DEF_SCROLLBAR_ORIENT, Tk_Offset(Scrollbar, orientUid), 0},
    {TK_CONFIG_RELIEF, "-relief", "relief", "Relief",
        DEF_SCROLLBAR_RELIEF, Tk_Offset(Scrollbar, relief), 0},
    {TK_CONFIG_INT, "-repeatdelay", "repeatDelay", "RepeatDelay",
        DEF_SCROLLBAR_REPEAT_DELAY, Tk_Offset(Scrollbar, repeatDelay), 0},
    {TK_CONFIG_INT, "-repeatinterval", "repeatInterval", "RepeatInterval",
        DEF_SCROLLBAR_REPEAT_INTERVAL, Tk_Offset(Scrollbar, repeatInterval), 0},
    {TK_CONFIG_PIXELS, "-width", "width", "Width",
        DEF_SCROLLBAR_WIDTH, Tk_Offset(Scrollbar, width), 0},
    {TK_CONFIG_END, (char *) NULL, (char *) NULL, (char *) NULL,
        (char *) NULL, 0, 0}
};

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

static void             ComputeScrollbarGeometry _ANSI_ARGS_((
                            Scrollbar *scrollPtr));
static int              ConfigureScrollbar _ANSI_ARGS_((Tcl_Interp *interp,
                            Scrollbar *scrollPtr, int argc, char **argv,
                            int flags));
static void             DestroyScrollbar _ANSI_ARGS_((ClientData clientData));
static void             DisplayScrollbar _ANSI_ARGS_((ClientData clientData));
static void             EventuallyRedraw _ANSI_ARGS_((Scrollbar *scrollPtr));
static void             ScrollbarEventProc _ANSI_ARGS_((ClientData clientData,
                            XEvent *eventPtr));
static void             ScrollbarMouseProc _ANSI_ARGS_((ClientData clientData,
                            XEvent *eventPtr));
static void             ScrollbarNewField _ANSI_ARGS_((Scrollbar *scrollPtr,
                            int field));
static int              ScrollbarPosition _ANSI_ARGS_((Scrollbar *scrollPtr,
                            int x, int y));
static void             ScrollbarTimerProc _ANSI_ARGS_((
                            ClientData clientData));
static int              ScrollbarWidgetCmd _ANSI_ARGS_((ClientData clientData,
                            Tcl_Interp *, int argc, char **argv));
static void             ScrollCmd _ANSI_ARGS_((Scrollbar *scrollPtr,
                            int unit));
\f
/*
 *--------------------------------------------------------------
 *
 * Tk_ScrollbarCmd --
 *
 *      This procedure is invoked to process the "scrollbar" 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_ScrollbarCmd(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 = (Tk_Window) clientData;
    register Scrollbar *scrollPtr;
    Tk_Window new;

    if (argc < 2) {
        Tcl_AppendResult(interp, "wrong # args:  should be \"",
                argv[0], " pathName ?options?\"", (char *) NULL);
        return TCL_ERROR;
    }

    new = Tk_CreateWindowFromPath(interp, tkwin, argv[1], (char *) NULL);
    if (new == NULL) {
        return TCL_ERROR;
    }

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

    scrollPtr = (Scrollbar *) ckalloc(sizeof(Scrollbar));
    scrollPtr->tkwin = new;
    scrollPtr->interp = interp;
    scrollPtr->command = NULL;
    scrollPtr->bgBorder = NULL;
    scrollPtr->fgBorder = NULL;
    scrollPtr->activeBorder = NULL;
    scrollPtr->copyGC = None;
    scrollPtr->mouseField = OUTSIDE;
    scrollPtr->pressField = -1;
    scrollPtr->totalUnits = 0;
    scrollPtr->windowUnits = 0;
    scrollPtr->firstUnit = 0;
    scrollPtr->lastUnit = 0;
    scrollPtr->cursor = None;
    scrollPtr->autoRepeat = NULL;
    scrollPtr->flags = 0;

    Tk_SetClass(scrollPtr->tkwin, "Scrollbar");
    Tk_CreateEventHandler(scrollPtr->tkwin, ExposureMask|StructureNotifyMask,
            ScrollbarEventProc, (ClientData) scrollPtr);
    Tk_CreateEventHandler(scrollPtr->tkwin, EnterWindowMask|LeaveWindowMask
            |PointerMotionMask|ButtonPressMask|ButtonReleaseMask,
            ScrollbarMouseProc, (ClientData) scrollPtr);
    Tcl_CreateCommand(interp, Tk_PathName(scrollPtr->tkwin), ScrollbarWidgetCmd,
            (ClientData) scrollPtr, (void (*)()) NULL);
    if (ConfigureScrollbar(interp, scrollPtr, argc-2, argv+2, 0) != TCL_OK) {
        goto error;
    }

    interp->result = Tk_PathName(scrollPtr->tkwin);
    return TCL_OK;

    error:
    Tk_DestroyWindow(scrollPtr->tkwin);
    return TCL_ERROR;
}
\f
/*
 *--------------------------------------------------------------
 *
 * ScrollbarWidgetCmd --
 *
 *      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
ScrollbarWidgetCmd(clientData, interp, argc, argv)
    ClientData clientData;      /* Information about scrollbar
                                         * widget. */
    Tcl_Interp *interp;                 /* Current interpreter. */
    int argc;                           /* Number of arguments. */
    char **argv;                        /* Argument strings. */
{
    register Scrollbar *scrollPtr = (Scrollbar *) clientData;
    int result = TCL_OK;
    int length;
    char c;

    if (argc < 2) {
        Tcl_AppendResult(interp, "wrong # args: should be \"",
                argv[0], " option ?arg arg ...?\"", (char *) NULL);
        return TCL_ERROR;
    }
    Tk_Preserve((ClientData) scrollPtr);
    c = argv[1][0];
    length = strlen(argv[1]);
    if ((c == 'c') && (strncmp(argv[1], "configure", length) == 0)) {
        if (argc == 2) {
            result = Tk_ConfigureInfo(interp, scrollPtr->tkwin, configSpecs,
                    (char *) scrollPtr, (char *) NULL, 0);
        } else if (argc == 3) {
            result = Tk_ConfigureInfo(interp, scrollPtr->tkwin, configSpecs,
                    (char *) scrollPtr, argv[2], 0);
        } else {
            result = ConfigureScrollbar(interp, scrollPtr, argc-2, argv+2,
                    TK_CONFIG_ARGV_ONLY);
        }
    } else if ((c == 'g') && (strncmp(argv[1], "get", length) == 0)) {
        if (argc != 2) {
            Tcl_AppendResult(interp, "wrong # args: should be \"",
                    argv[0], " get\"", (char *) NULL);
            goto error;
        }
        sprintf(interp->result, "%d %d %d %d", scrollPtr->totalUnits,
                scrollPtr->windowUnits, scrollPtr->firstUnit,
                scrollPtr->lastUnit);
    } else if ((c == 's') && (strncmp(argv[1], "set", length) == 0)) {
        int totalUnits, windowUnits, firstUnit, lastUnit;

        if (argc != 6) {
            Tcl_AppendResult(interp, "wrong # args: should be \"",
                    argv[0],
                    " set totalUnits windowUnits firstUnit lastUnit\"",
                    (char *) NULL);
            goto error;
        }
        if (Tcl_GetInt(interp, argv[2], &totalUnits) != TCL_OK) {
            goto error;
        }
        if (totalUnits < 0) {
            sprintf(interp->result, "illegal totalUnits %d", totalUnits);
            goto error;
        }
        if (Tcl_GetInt(interp, argv[3], &windowUnits) != TCL_OK) {
            goto error;
        }
        if (windowUnits < 0) {
            sprintf(interp->result, "illegal windowUnits %d", windowUnits);
            goto error;
        }
        if (Tcl_GetInt(interp, argv[4], &firstUnit) != TCL_OK) {
            goto error;
        }
        if (Tcl_GetInt(interp, argv[5], &lastUnit) != TCL_OK) {
            goto error;
        }
        if (totalUnits > 0) {
            if (lastUnit < firstUnit) {
                sprintf(interp->result, "illegal lastUnit %d", lastUnit);
                goto error;
            }
        } else {
            firstUnit = lastUnit = 0;
        }
        scrollPtr->totalUnits = totalUnits;
        scrollPtr->windowUnits = windowUnits;
        scrollPtr->firstUnit = firstUnit;
        scrollPtr->lastUnit = lastUnit;
        ComputeScrollbarGeometry(scrollPtr);
        EventuallyRedraw(scrollPtr);
    } else {
        Tcl_AppendResult(interp, "bad option \"", argv[1],
                "\":  must be configure, get, or set", (char *) NULL);
        goto error;
    }
    Tk_Release((ClientData) scrollPtr);
    return result;

    error:
    Tk_Release((ClientData) scrollPtr);
    return TCL_ERROR;
}
\f
/*
 *----------------------------------------------------------------------
 *
 * DestroyScrollbar --
 *
 *      This procedure is invoked by Tk_EventuallyFree or Tk_Release
 *      to clean up the internal structure of a scrollbar at a safe time
 *      (when no-one is using it anymore).
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Everything associated with the scrollbar is freed up.
 *
 *----------------------------------------------------------------------
 */

static void
DestroyScrollbar(clientData)
    ClientData clientData;      /* Info about scrollbar widget. */
{
    register Scrollbar *scrollPtr = (Scrollbar *) clientData;

    if (scrollPtr->command != NULL) {
        ckfree(scrollPtr->command);
    }
    if (scrollPtr->bgBorder != NULL) {
        Tk_Free3DBorder(scrollPtr->bgBorder);
    }
    if (scrollPtr->fgBorder != NULL) {
        Tk_Free3DBorder(scrollPtr->fgBorder);
    }
    if (scrollPtr->activeBorder != NULL) {
        Tk_Free3DBorder(scrollPtr->activeBorder);
    }
    if (scrollPtr->copyGC != None) {
        Tk_FreeGC(scrollPtr->copyGC);
    }
    if (scrollPtr->cursor != None) {
        Tk_FreeCursor(scrollPtr->cursor);
    }
    ckfree((char *) scrollPtr);
}
\f
/*
 *----------------------------------------------------------------------
 *
 * ConfigureScrollbar --
 *
 *      This procedure is called to process an argv/argc list, plus
 *      the Tk option database, in order to configure (or
 *      reconfigure) a scrollbar widget.
 *
 * Results:
 *      The return value is a standard Tcl result.  If TCL_ERROR is
 *      returned, then interp->result contains an error message.
 *
 * Side effects:
 *      Configuration information, such as colors, border width,
 *      etc. get set for scrollPtr;  old resources get freed,
 *      if there were any.
 *
 *----------------------------------------------------------------------
 */

static int
ConfigureScrollbar(interp, scrollPtr, argc, argv, flags)
    Tcl_Interp *interp;                 /* Used for error reporting. */
    register Scrollbar *scrollPtr;      /* Information about widget;  may or
                                         * may not already have values for
                                         * some fields. */
    int argc;                           /* Number of valid entries in argv. */
    char **argv;                        /* Arguments. */
    int flags;                          /* Flags to pass to
                                         * Tk_ConfigureWidget. */
{
    int length;
    XGCValues gcValues;

    if (Tk_ConfigureWidget(interp, scrollPtr->tkwin, configSpecs,
            argc, argv, (char *) scrollPtr, flags) != TCL_OK) {
        return TCL_ERROR;
    }

    /*
     * A few options need special processing, such as parsing the
     * orientation or setting the background from a 3-D border.
     */

    length = strlen(scrollPtr->orientUid);
    if (strncmp(scrollPtr->orientUid, "vertical", length) == 0) {
        scrollPtr->vertical = 1;
    } else if (strncmp(scrollPtr->orientUid, "horizontal", length) == 0) {
        scrollPtr->vertical = 0;
    } else {
        Tcl_AppendResult(interp, "bad orientation \"", scrollPtr->orientUid,
                "\": must be vertical or horizontal", (char *) NULL);
        return TCL_ERROR;
    }

    if (scrollPtr->command != NULL) {
        scrollPtr->commandSize = strlen(scrollPtr->command);
    } else {
        scrollPtr->commandSize = 0;
    }

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

    if (scrollPtr->copyGC == None) {
        gcValues.graphics_exposures = False;
        scrollPtr->copyGC = Tk_GetGC(scrollPtr->tkwin, GCGraphicsExposures,
            &gcValues);
    }

    /*
     * Register the desired geometry for the window (leave enough space
     * for the two arrows plus a minimum-size slider, plus border around
     * the whole window, if any).  Then arrange for the window to be
     * redisplayed.
     */

    ComputeScrollbarGeometry(scrollPtr);
    EventuallyRedraw(scrollPtr);
    return TCL_OK;
}
\f
/*
 *--------------------------------------------------------------
 *
 * DisplayScrollbar --
 *
 *      This procedure redraws the contents of a scrollbar window.
 *      It is invoked as a do-when-idle handler, so it only runs
 *      when there's nothing else for the application to do.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Information appears on the screen.
 *
 *--------------------------------------------------------------
 */

static void
DisplayScrollbar(clientData)
    ClientData clientData;      /* Information about window. */
{
    register Scrollbar *scrollPtr = (Scrollbar *) clientData;
    register Tk_Window tkwin = scrollPtr->tkwin;
    XPoint points[7];
    Tk_3DBorder border;
    int relief, width, fieldLength;
    Pixmap pixmap;

    if ((scrollPtr->tkwin == NULL) || !Tk_IsMapped(tkwin)) {
        goto done;
    }

    if (scrollPtr->vertical) {
        width = Tk_Width(tkwin) - 2*scrollPtr->offset;
    } else {
        width = Tk_Height(tkwin) - 2*scrollPtr->offset;
    }

    /*
     * In order to avoid screen flashes, this procedure redraws
     * the scrollbar in a pixmap, then copies the pixmap to the
     * screen in a single operation.  This means that there's no
     * point in time where the on-sreen image has been cleared.
     */

    pixmap = XCreatePixmap(Tk_Display(tkwin), Tk_WindowId(tkwin),
            Tk_Width(tkwin), Tk_Height(tkwin),
            Tk_DefaultDepth(Tk_Screen(tkwin)));
    Tk_Fill3DRectangle(Tk_Display(tkwin), pixmap, scrollPtr->bgBorder,
            0, 0, Tk_Width(tkwin), Tk_Height(tkwin),
            scrollPtr->borderWidth, scrollPtr->relief);

    /*
     * Draw the top or left arrow.  The coordinates of the polygon
     * points probably seem odd, but they were carefully chosen with
     * respect to X's rules for filling polygons.  These point choices
     * cause the arrows to just fill the narrow dimension of the
     * scrollbar and be properly centered.
     */

    if (scrollPtr->mouseField == TOP_ARROW) {
        border = scrollPtr->activeBorder;
        relief = scrollPtr->pressField == TOP_ARROW ? TK_RELIEF_SUNKEN
                : TK_RELIEF_RAISED;
    } else {
        border = scrollPtr->fgBorder;
        relief = TK_RELIEF_RAISED;
    }
    if (scrollPtr->vertical) {
        points[0].x = scrollPtr->offset - 1;
        points[0].y = scrollPtr->arrowLength + scrollPtr->offset;
        points[1].x = width + scrollPtr->offset;
        points[1].y = points[0].y;
        points[2].x = width/2 + scrollPtr->offset;
        points[2].y = scrollPtr->offset - 1;
        Tk_Fill3DPolygon(Tk_Display(tkwin), pixmap, border,
                points, 3, scrollPtr->borderWidth, relief);
    } else {
        points[0].x = scrollPtr->arrowLength + scrollPtr->offset;
        points[0].y = scrollPtr->offset - 1;
        points[1].x = scrollPtr->offset;
        points[1].y = width/2 + scrollPtr->offset;
        points[2].x = points[0].x;
        points[2].y = width + scrollPtr->offset;
        Tk_Fill3DPolygon(Tk_Display(tkwin), pixmap, border,
                points, 3, scrollPtr->borderWidth, relief);
    }

    /*
     * Display the bottom or right arrow.
     */

    if (scrollPtr->mouseField == BOTTOM_ARROW) {
        border = scrollPtr->activeBorder;
        relief = scrollPtr->pressField == BOTTOM_ARROW ? TK_RELIEF_SUNKEN
                : TK_RELIEF_RAISED;
    } else {
        border = scrollPtr->fgBorder;
        relief = TK_RELIEF_RAISED;
    }
    if (scrollPtr->vertical) {
        points[0].x = scrollPtr->offset;
        points[0].y = Tk_Height(tkwin) - scrollPtr->arrowLength
                - scrollPtr->offset;
        points[1].x = width/2 + scrollPtr->offset;
        points[1].y = Tk_Height(tkwin) - scrollPtr->offset;
        points[2].x = width + scrollPtr->offset;
        points[2].y = points[0].y;
        Tk_Fill3DPolygon(Tk_Display(tkwin), pixmap, border,
                points, 3, scrollPtr->borderWidth, relief);
    } else {
        points[0].x = Tk_Width(tkwin) - scrollPtr->arrowLength
                - scrollPtr->offset;
        points[0].y = scrollPtr->offset - 1;
        points[1].x = points[0].x;
        points[1].y = width + scrollPtr->offset;
        points[2].x = Tk_Width(tkwin) - scrollPtr->offset;
        points[2].y = width/2 + scrollPtr->offset;
        Tk_Fill3DPolygon(Tk_Display(tkwin), pixmap, border,
                points, 3, scrollPtr->borderWidth, relief);
    }

    /*
     * Display the slider.
     */

    if (scrollPtr->mouseField == SLIDER) {
        border = scrollPtr->activeBorder;
        relief = scrollPtr->pressField == SLIDER ? TK_RELIEF_SUNKEN
                : TK_RELIEF_RAISED;
    } else {
        border = scrollPtr->fgBorder;
        relief = TK_RELIEF_RAISED;
    }
    fieldLength = (scrollPtr->vertical ? Tk_Height(tkwin) : Tk_Width(tkwin))
            - 2*(scrollPtr->arrowLength + scrollPtr->offset);
    if (fieldLength < 0) {
        fieldLength = 0;
    }
    if (scrollPtr->vertical) {
        Tk_Fill3DRectangle(Tk_Display(tkwin), pixmap, border,
                1 + scrollPtr->offset, scrollPtr->sliderFirst,
                width-2, scrollPtr->sliderLast - scrollPtr->sliderFirst,
                scrollPtr->borderWidth, relief);
    } else {
        Tk_Fill3DRectangle(Tk_Display(tkwin), pixmap, border,
                scrollPtr->sliderFirst, 1 + scrollPtr->offset,
                scrollPtr->sliderLast - scrollPtr->sliderFirst, width-2,
                scrollPtr->borderWidth, relief);
    }

    /*
     * Copy the information from the off-screen pixmap onto the screen,
     * then delete the pixmap.
     */

    XCopyArea(Tk_Display(tkwin), pixmap, Tk_WindowId(tkwin),
        scrollPtr->copyGC, 0, 0, Tk_Width(tkwin), Tk_Height(tkwin), 0, 0);
    XFreePixmap(Tk_Display(tkwin), pixmap);

    done:
    scrollPtr->flags &= ~REDRAW_PENDING;
}
\f
/*
 *--------------------------------------------------------------
 *
 * ScrollbarEventProc --
 *
 *      This procedure is invoked by the Tk dispatcher for various
 *      events on scrollbars.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      When the window gets deleted, internal structures get
 *      cleaned up.  When it gets exposed, it is redisplayed.
 *
 *--------------------------------------------------------------
 */

static void
ScrollbarEventProc(clientData, eventPtr)
    ClientData clientData;      /* Information about window. */
    XEvent *eventPtr;           /* Information about event. */
{
    Scrollbar *scrollPtr = (Scrollbar *) clientData;

    if ((eventPtr->type == Expose) && (eventPtr->xexpose.count == 0)) {
        EventuallyRedraw(scrollPtr);
    } else if (eventPtr->type == DestroyNotify) {
        Tcl_DeleteCommand(scrollPtr->interp, Tk_PathName(scrollPtr->tkwin));
        scrollPtr->tkwin = NULL;
        if (scrollPtr->flags & REDRAW_PENDING) {
            Tk_CancelIdleCall(DisplayScrollbar, (ClientData) scrollPtr);
        }
        Tk_EventuallyFree((ClientData) scrollPtr, DestroyScrollbar);
    } else if (eventPtr->type == ConfigureNotify) {
        ComputeScrollbarGeometry(scrollPtr);
    }
}
\f
/*
 *----------------------------------------------------------------------
 *
 * ComputeScrollbarGeometry --
 *
 *      After changes in a scrollbar's size or configuration, this
 *      procedure recomputes various geometry information used in
 *      displaying the scrollbar.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      The scrollbar will be displayed differently.
 *
 *----------------------------------------------------------------------
 */

static void
ComputeScrollbarGeometry(scrollPtr)
    register Scrollbar *scrollPtr;      /* Scrollbar whose geometry may
                                         * have changed. */
{
    int width, fieldLength;

    if (scrollPtr->relief == TK_RELIEF_FLAT) {
        scrollPtr->offset = 0;
    } else {
        scrollPtr->offset = scrollPtr->borderWidth;
    }
    width = (scrollPtr->vertical) ? Tk_Width(scrollPtr->tkwin)
            : Tk_Height(scrollPtr->tkwin);
    scrollPtr->arrowLength =
                (((width - 2*scrollPtr->offset)*173) + 100) / 200;
    fieldLength = (scrollPtr->vertical ? Tk_Height(scrollPtr->tkwin)
            : Tk_Width(scrollPtr->tkwin))
            - 2*(scrollPtr->arrowLength + scrollPtr->offset);
    if (fieldLength < 0) {
        fieldLength = 0;
    }
    if (scrollPtr->totalUnits <= 0) {
        scrollPtr->sliderFirst = 0;
        scrollPtr->sliderLast = fieldLength;
    } else {
        scrollPtr->sliderFirst = (fieldLength*scrollPtr->firstUnit
                + scrollPtr->totalUnits/2)/scrollPtr->totalUnits;
        scrollPtr->sliderLast = (fieldLength*(scrollPtr->lastUnit+1)
                + scrollPtr->totalUnits/2)/scrollPtr->totalUnits;

        /*
         * Adjust the slider so that some piece of it is always
         * displayed in the scrollbar and so that it has at least
         * a minimal width (so it can be grabbed with the mouse).
         */

        if (scrollPtr->sliderFirst > (fieldLength - 2*scrollPtr->borderWidth)) {
            scrollPtr->sliderFirst = fieldLength - 2*scrollPtr->borderWidth;
        }
        if (scrollPtr->sliderFirst < 0) {
            scrollPtr->sliderFirst = 0;
        }
        if (scrollPtr->sliderLast < (scrollPtr->sliderFirst
                + 2*scrollPtr->borderWidth)) {
            scrollPtr->sliderLast = scrollPtr->sliderFirst
                    + 2*scrollPtr->borderWidth;
        }
        if (scrollPtr->sliderLast > fieldLength) {
            scrollPtr->sliderLast = fieldLength;
        }
    }
    scrollPtr->sliderFirst += scrollPtr->arrowLength + scrollPtr->offset;
    scrollPtr->sliderLast += scrollPtr->arrowLength + scrollPtr->offset;

    /*
     * Register the desired geometry for the window (leave enough space
     * for the two arrows plus a minimum-size slider, plus border around
     * the whole window, if any).  Then arrange for the window to be
     * redisplayed.
     */

    if (scrollPtr->vertical) {
        Tk_GeometryRequest(scrollPtr->tkwin,
                scrollPtr->width + 2*scrollPtr->offset,
                2*(scrollPtr->arrowLength + scrollPtr->borderWidth
                + scrollPtr->offset));
    } else {
        Tk_GeometryRequest(scrollPtr->tkwin,
                2*(scrollPtr->arrowLength + scrollPtr->borderWidth
                + scrollPtr->offset), scrollPtr->width + 2*scrollPtr->offset);
    }
    Tk_SetInternalBorder(scrollPtr->tkwin, scrollPtr->borderWidth);

}
\f
/*
 *--------------------------------------------------------------
 *
 * ScrollbarPosition --
 *
 *      Determine the scrollbar element corresponding to a
 *      given position.
 *
 * Results:
 *      One of TOP_ARROW, TOP_GAP, etc., indicating which element
 *      of the scrollbar covers the position given by (x, y).  If
 *      (x,y) is outside the scrollbar entirely, then OUTSIDE is
 *      returned.
 *
 * Side effects:
 *      None.
 *
 *--------------------------------------------------------------
 */

static int
ScrollbarPosition(scrollPtr, x, y)
    register Scrollbar *scrollPtr;      /* Scrollbar widget record. */
    int x, y;                           /* Coordinates within scrollPtr's
                                         * window. */
{
    int length, width, tmp;

    if (scrollPtr->vertical) {
        length = Tk_Height(scrollPtr->tkwin);
        width = Tk_Width(scrollPtr->tkwin);
    } else {
        tmp = x;
        x = y;
        y = tmp;
        length = Tk_Width(scrollPtr->tkwin);
        width = Tk_Height(scrollPtr->tkwin);
    }

    if ((x < 0) || (x > width) || (y < 0)) {
        return OUTSIDE;
    }

    /*
     * All of the calculations in this procedure mirror those in
     * DisplayScrollbar.  Be sure to keep the two consistent.
     */

    if (y < (scrollPtr->offset + scrollPtr->arrowLength)) {
        return TOP_ARROW;
    }
    if (y < scrollPtr->sliderFirst) {
        return TOP_GAP;
    }
    if (y < scrollPtr->sliderLast) {
        return SLIDER;
    }
    if (y >= (length - (scrollPtr->arrowLength + scrollPtr->offset))) {
        return BOTTOM_ARROW;
    }
    return BOTTOM_GAP;
}
\f
/*
 *--------------------------------------------------------------
 *
 * ScrollbarMouseProc --
 *
 *      This procedure is called back by Tk in response to
 *      mouse events such as window entry, window exit, mouse
 *      motion, and button presses.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      This procedure implements the "feel" of the scrollbar
 *      by issuing scrolling commands in response to button presses
 *      and mouse motion.
 *
 *--------------------------------------------------------------
 */

static void
ScrollbarMouseProc(clientData, eventPtr)
    ClientData clientData;              /* Information about window. */
    register XEvent *eventPtr;          /* Information about event. */
{
    register Scrollbar *scrollPtr = (Scrollbar *) clientData;

    Tk_Preserve((ClientData) scrollPtr);
    if (eventPtr->type == EnterNotify) {
        if (scrollPtr->pressField == -1) {
            ScrollbarNewField(scrollPtr,
                    ScrollbarPosition(scrollPtr, eventPtr->xcrossing.x,
                    eventPtr->xcrossing.y));
        }
    } else if (eventPtr->type == LeaveNotify) {
        if (scrollPtr->pressField == -1) {
            ScrollbarNewField(scrollPtr, OUTSIDE);
        }
    } else if (eventPtr->type == MotionNotify) {
        if (scrollPtr->pressField == SLIDER) {
            int delta, length, newFirst;

            if (scrollPtr->vertical) {
                delta = eventPtr->xmotion.y - scrollPtr->pressPos;
                length = Tk_Height(scrollPtr->tkwin)
                        - 2*(scrollPtr->arrowLength + scrollPtr->offset);
            } else {
                delta = eventPtr->xmotion.x - scrollPtr->pressPos;
                length = Tk_Width(scrollPtr->tkwin)
                        - 2*(scrollPtr->arrowLength + scrollPtr->offset);
            }

            /*
             * Do the division with positive numbers to avoid
             * differences in negative-number truncation on different
             * machines.
             */

            if (delta >= 0) {
                newFirst = scrollPtr->pressFirstUnit
                        + ((delta * scrollPtr->totalUnits) + (length/2))
                        / length;
            } else {
                newFirst = scrollPtr->pressFirstUnit
                        - (((-delta) * scrollPtr->totalUnits) + (length/2))
                        / length;
            }
            ScrollCmd(scrollPtr, newFirst);
        } else if (scrollPtr->pressField == -1) {
            ScrollbarNewField(scrollPtr,
                    ScrollbarPosition(scrollPtr, eventPtr->xmotion.x,
                    eventPtr->xmotion.y));
        }
    } else if ((eventPtr->type == ButtonPress)
            && (eventPtr->xbutton.state == 0)) {
        scrollPtr->pressField = scrollPtr->mouseField;
        if (scrollPtr->pressField != SLIDER) {
            scrollPtr->autoRepeat = Tk_CreateTimerHandler(
                    scrollPtr->repeatDelay,
                    ScrollbarTimerProc, (ClientData) scrollPtr);
        }
        if (scrollPtr->vertical) {
            scrollPtr->pressPos = eventPtr->xbutton.y;
        } else {
            scrollPtr->pressPos = eventPtr->xbutton.x;
        }
        scrollPtr->pressFirstUnit = scrollPtr->firstUnit;
        if (scrollPtr->pressFirstUnit <= -scrollPtr->windowUnits) {
            scrollPtr->pressFirstUnit = 1-scrollPtr->windowUnits;
        }
        if (scrollPtr->pressFirstUnit >= scrollPtr->totalUnits) {
            scrollPtr->pressFirstUnit = scrollPtr->totalUnits-1;
        }
        EventuallyRedraw(scrollPtr);
    } else if (eventPtr->type == ButtonRelease) {
        if (scrollPtr->pressField == scrollPtr->mouseField) {
            switch (scrollPtr->pressField) {
                case TOP_ARROW:
                    ScrollCmd(scrollPtr, scrollPtr->firstUnit-1);
                    break;
                case TOP_GAP:
                    if (scrollPtr->windowUnits <= 1) {
                        ScrollCmd(scrollPtr, scrollPtr->firstUnit - 1);
                    } else {
                        ScrollCmd(scrollPtr, scrollPtr->firstUnit
                                - (scrollPtr->windowUnits-1));
                    }
                    break;
                case BOTTOM_GAP: {
                    if (scrollPtr->windowUnits <= 1) {
                        ScrollCmd(scrollPtr, scrollPtr->firstUnit + 1);
                    } else {
                        ScrollCmd(scrollPtr, scrollPtr->firstUnit
                                + (scrollPtr->windowUnits-1));
                    }
                    break;
                }
                case BOTTOM_ARROW:
                    ScrollCmd(scrollPtr, scrollPtr->firstUnit+1);
                    break;
            }
        }
        if (scrollPtr->autoRepeat != NULL) {
            Tk_DeleteTimerHandler(scrollPtr->autoRepeat);
            scrollPtr->autoRepeat = NULL;
        }
        EventuallyRedraw(scrollPtr);
        scrollPtr->pressField = -1;
        ScrollbarNewField(scrollPtr,
                ScrollbarPosition(scrollPtr, eventPtr->xbutton.x,
                eventPtr->xbutton.y));
    }
    Tk_Release((ClientData) scrollPtr);
}
\f
/*
 *--------------------------------------------------------------
 *
 * ScrollCmd --
 *
 *      This procedure takes care of invoking a scrolling Tcl
 *      command and reporting any error that occurs in it.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      A Tcl command is invoked, and an additional error-processing
 *      command may also be invoked.
 *
 *--------------------------------------------------------------
 */

static void
ScrollCmd(scrollPtr, unit)
    register Scrollbar *scrollPtr;      /* Scrollbar from which to issue
                                         * command. */
    int unit;                           /* Unit position within thing being
                                         * being displayed that should appear
                                         * at top or right of screen. */
{
    char string[20];
    int result;

    if ((unit == scrollPtr->firstUnit) || (scrollPtr->command == NULL)) {
        return;
    }
    sprintf(string, " %d", unit);
    result = Tcl_VarEval(scrollPtr->interp, scrollPtr->command, string,
            (char *) NULL);
    if (result != TCL_OK) {
        TkBindError(scrollPtr->interp);
    }
}
\f
/*
 *--------------------------------------------------------------
 *
 * EventuallyRedraw --
 *
 *      Arrange for one or more of the fields of a scrollbar
 *      to be redrawn.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      None.
 *
 *--------------------------------------------------------------
 */

static void
EventuallyRedraw(scrollPtr)
    register Scrollbar *scrollPtr;      /* Information about widget. */
{
    if ((scrollPtr->tkwin == NULL) || (!Tk_IsMapped(scrollPtr->tkwin))) {
        return;
    }
    if ((scrollPtr->flags & REDRAW_PENDING) == 0) {
        Tk_DoWhenIdle(DisplayScrollbar, (ClientData) scrollPtr);
        scrollPtr->flags |= REDRAW_PENDING;
    }
}
\f
/*
 *--------------------------------------------------------------
 *
 * ScrollbarNewField --
 *
 *      This procedure is called to declare that the mouse is in
 *      a particular field of the scrollbar (e.g. top arrow), so
 *      that the field can be highlighed and the previous field
 *      can be returned to normal display.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Fields may be redisplayed.
 *
 *--------------------------------------------------------------
 */

static void
ScrollbarNewField(scrollPtr, field)
    register Scrollbar *scrollPtr;      /* Information about widget. */
    int field;                          /* Identifies field under mouse,
                                         * e.g. TOP_ARROW. */
{
    if (field == scrollPtr->mouseField) {
        return;
    }
    EventuallyRedraw(scrollPtr);
    scrollPtr->mouseField = field;
}
\f
/*
 *--------------------------------------------------------------
 *
 * ScrollbarTimerProc --
 *
 *      This procedure is invoked as a Tk timer handler for actions
 *      that auto-repeat (mouse presses in an arrow or gap).  It
 *      performs the auto-repeat action.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Whatever action corresponds to the current mouse button
 *      is repeated, and this procedure is rescheduled to execute
 *      again later.
 *
 *--------------------------------------------------------------
 */

static void
ScrollbarTimerProc(clientData)
    ClientData clientData;      /* Information about widget. */
{
    register Scrollbar *scrollPtr = (Scrollbar *) clientData;

    Tk_Preserve((ClientData) scrollPtr);
    switch(scrollPtr->pressField) {
        case TOP_ARROW:
            ScrollCmd(scrollPtr, scrollPtr->firstUnit-1);
            break;
        case TOP_GAP:
            ScrollCmd(scrollPtr, scrollPtr->firstUnit
                    - (scrollPtr->windowUnits-1));
            break;
        case BOTTOM_GAP: {
            ScrollCmd(scrollPtr, scrollPtr->firstUnit
                    + (scrollPtr->windowUnits-1));
            break;
        }
        case BOTTOM_ARROW:
            ScrollCmd(scrollPtr, scrollPtr->firstUnit+1);
            break;
    }
    if (scrollPtr->tkwin != NULL) {
        scrollPtr->autoRepeat = Tk_CreateTimerHandler(
                scrollPtr->repeatInterval, ScrollbarTimerProc,
                (ClientData) scrollPtr);
    }
    Tk_Release((ClientData) scrollPtr);
}