path: root/macosx/tkMacOSXScrlbr.c

/* 
 * tkMacOSXScrollbar.c --
 *
 *        This file implements the Macintosh specific portion of the scrollbar
 *        widget.  The Macintosh scrollbar may also draw a windows grow
 *        region under certain cases.
 *
 * Copyright (c) 1996 by Sun Microsystems, Inc.
 * Copyright 2001, Apple Computer, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tkMacOSXScrlbr.c,v 1.6 2003/11/16 01:01:32 vincentdarley Exp $
 */

#include "tkScrollbar.h"
#include "tkMacOSXInt.h"

#include <Carbon/Carbon.h>

#include "tkMacOSXDebug.h"
/*
 * The following definitions should really be in MacOS
 * header files.  They are included here as this is the only
 * file that needs the declarations.
 */
typedef pascal void (*ThumbActionFunc)(void);

typedef ThumbActionFunc ThumbActionUPP;

enum {
    uppThumbActionProcInfo = kPascalStackBased
};

#define NewThumbActionProc(userRoutine) ((ThumbActionUPP) (userRoutine))

/*
 * Minimum slider length, in pixels (designed to make sure that the slider
 * is always easy to grab with the mouse).
 */

#define MIN_SLIDER_LENGTH       5
#define MIN_SCROLLBAR_VALUE     0
#define MAX_SCROLLBAR_VALUE     1000
#define MAX_SCROLLBAR_DVALUE    1000.0

/*
 * Declaration of Windows specific scrollbar structure.
 */

typedef struct MacScrollbar {
    TkScrollbar info;            /* Generic scrollbar info */
    ControlRef  sbHandle;        /* Opaque handle to the Scrollbar contol struct */
    int         macFlags;        /* Various flags; see below */
} MacScrollbar;

/* Handle to the Scrollbar control structure */
        

/*
 * Flag bits for scrollbars on the Mac:
 * 
 * ALREADY_DEAD:                Non-zero means this scrollbar has been
 *                                destroyed, but has not been cleaned up.
 * IN_MODAL_LOOP:                Non-zero means this scrollbar is in the middle
 *                                of a modal loop.
 * ACTIVE:                        Non-zero means this window is currently
 *                                active (in the foreground).
 * FLUSH_TOP:                        Flush with top of Mac window.
 * FLUSH_BOTTOM:                Flush with bottom of Mac window.
 * FLUSH_RIGHT:                        Flush with right of Mac window.
 * FLUSH_LEFT:                        Flush with left of Mac window.
 * SCROLLBAR_GROW:                Non-zero means this window draws the grow
 *                                region for the toplevel window.
 * AUTO_ADJUST:                        Non-zero means we automatically adjust
 *                                the size of the widget to align correctly
 *                                along a Mac window.
 * DRAW_GROW:                        Non-zero means we draw the grow region.
 */

#define ALREADY_DEAD             1
#define IN_MODAL_LOOP            2
#define ACTIVE                   4
#define FLUSH_TOP                8
#define FLUSH_BOTTOM             16
#define FLUSH_RIGHT              32
#define FLUSH_LEFT               64
#define SCROLLBAR_GROW           128
#define AUTO_ADJUST              256
#define DRAW_GROW                512

/*
 * Globals uses locally in this file.
 */
static ControlActionUPP scrollActionProc = NULL; /* Pointer to func. */
static ThumbActionUPP thumbActionProc = NULL;    /* Pointer to func. */
static TkScrollbar *activeScrollPtr = NULL;        /* Non-null when in thumb */
                                                 /* proc. */
/*
 * Forward declarations for procedures defined later in this file:
 */

static pascal void ScrollbarActionProc _ANSI_ARGS_((ControlRef theControl, ControlPartCode partCode));
static int         ScrollbarBindProc _ANSI_ARGS_((ClientData clientData,
    Tcl_Interp *interp, XEvent *eventPtr,
    Tk_Window tkwin, KeySym keySym));
static void        ScrollbarEventProc _ANSI_ARGS_(( ClientData clientData, XEvent *eventPtr));
static pascal void ThumbActionProc _ANSI_ARGS_((void));
static void        UpdateControlValues _ANSI_ARGS_((MacScrollbar *macScrollPtr));
                    
/*
 * The class procedure table for the scrollbar widget.  Leave the proc fields
 * initialized to NULL, which should happen automatically because of the scope
 * at which the variable is declared.
 */

Tk_ClassProcs tkpScrollbarProcs = {
    sizeof(Tk_ClassProcs)        /* size */
};

/*
 *----------------------------------------------------------------------
 *
 * TkpCreateScrollbar --
 *
 *        Allocate a new TkScrollbar structure.
 *
 * Results:
 *        Returns a newly allocated TkScrollbar structure.
 *
 * Side effects:
 *        None.
 *
 *----------------------------------------------------------------------
 */

TkScrollbar *
TkpCreateScrollbar(
    Tk_Window tkwin)        /* New Tk Window. */
{
    MacScrollbar * macScrollPtr;
    TkWindow *winPtr = (TkWindow *)tkwin;
    
    if (scrollActionProc == NULL) {
        scrollActionProc = NewControlActionUPP (ScrollbarActionProc);
        thumbActionProc = NewThumbActionProc(ThumbActionProc);
    }

    macScrollPtr = (MacScrollbar *) ckalloc(sizeof(MacScrollbar));
    macScrollPtr->sbHandle = NULL;
    macScrollPtr->macFlags = 0;

    Tk_CreateEventHandler(tkwin, ActivateMask|ExposureMask|
        StructureNotifyMask|FocusChangeMask,
        ScrollbarEventProc, (ClientData) macScrollPtr);

    if (!Tcl_GetAssocData(winPtr->mainPtr->interp, "TkScrollbar", NULL)) {
        Tcl_SetAssocData(winPtr->mainPtr->interp, "TkScrollbar", NULL, (ClientData)1);
        TkCreateBindingProcedure(winPtr->mainPtr->interp,
            winPtr->mainPtr->bindingTable,
            (ClientData)Tk_GetUid("Scrollbar"), "<ButtonPress>",
            ScrollbarBindProc, NULL, NULL);
    }
    return (TkScrollbar *) macScrollPtr;
}

/*
 *--------------------------------------------------------------
 *
 * TkpDisplayScrollbar --
 *
 *        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.
 *
 *--------------------------------------------------------------
 */

void
TkpDisplayScrollbar(
    ClientData clientData)        /* Information about window. */
{
    TkScrollbar *scrollPtr = (TkScrollbar *) clientData;
    MacScrollbar *macScrollPtr = (MacScrollbar *) clientData;
    Tk_Window tkwin = scrollPtr->tkwin;
    
    MacDrawable *macDraw;
    CGrafPtr saveWorld;
    GDHandle saveDevice;
    GWorldPtr destPort;
    WindowRef windowRef;
    
    if ((scrollPtr->tkwin == NULL) || !Tk_IsMapped(tkwin)) {
        goto done;
    }

    /*
     * Draw the focus or any 3D relief we may have.
     */
    if (scrollPtr->highlightWidth != 0) {
        GC fgGC, bgGC;

        bgGC = Tk_GCForColor(scrollPtr->highlightBgColorPtr,
            Tk_WindowId(tkwin));

        if (scrollPtr->flags & GOT_FOCUS) {
            fgGC = Tk_GCForColor(scrollPtr->highlightColorPtr,
                Tk_WindowId(tkwin));
            TkpDrawHighlightBorder(tkwin, fgGC, bgGC, scrollPtr->highlightWidth,
                Tk_WindowId(tkwin));
        } else {
            TkpDrawHighlightBorder(tkwin, bgGC, bgGC, scrollPtr->highlightWidth,
                Tk_WindowId(tkwin));
        }
    }
    Tk_Draw3DRectangle(tkwin, Tk_WindowId(tkwin), scrollPtr->bgBorder,
        scrollPtr->highlightWidth, scrollPtr->highlightWidth,
        Tk_Width(tkwin) - 2*scrollPtr->highlightWidth,
        Tk_Height(tkwin) - 2*scrollPtr->highlightWidth,
        scrollPtr->borderWidth, scrollPtr->relief);

    /*
     * Set up port for drawing Macintosh control.
     */
    macDraw = (MacDrawable *) Tk_WindowId(tkwin);
    destPort = TkMacOSXGetDrawablePort(Tk_WindowId(tkwin));
    GetGWorld(&saveWorld, &saveDevice);
    SetGWorld(destPort, NULL);
    TkMacOSXSetUpClippingRgn(Tk_WindowId(tkwin));

    if (macScrollPtr->sbHandle == NULL) {
        Rect r;
        SInt16 initialValue;
        SInt16 minValue;
        SInt16 maxValue;
        SInt16 procID;
        WindowRef frontNonFloating;
        
        r.left = r.top = 0;
        r.right = r.bottom = 1;

        minValue = MIN_SCROLLBAR_VALUE;
        maxValue = MAX_SCROLLBAR_VALUE;
        initialValue = (minValue + maxValue)/2;
        procID = kControlScrollBarLiveProc;

        windowRef = GetWindowFromPort(destPort);
        CreateScrollBarControl(windowRef, &r, initialValue,
                                minValue, maxValue,
                                maxValue - minValue, true,
                                NULL, &(macScrollPtr->sbHandle));
        SetControlReference(macScrollPtr->sbHandle, (SInt32) scrollPtr);
        
        /*
         * If we are foremost then make us active.
         */
        
        frontNonFloating = FrontNonFloatingWindow();
        
        if ((windowRef == FrontWindow()) || TkpIsWindowFloating(windowRef)) {
            macScrollPtr->macFlags |= ACTIVE;
        }
    }

    /*
     * Adjust the control size based on its width...
     */

    if (macScrollPtr->info.width < 13) {
        SetControlData(macScrollPtr->sbHandle, kControlNoPart, kControlSizeTag,
                sizeof(kControlSizeSmall), (void *) kControlSizeSmall);
    } else {
        SetControlData(macScrollPtr->sbHandle, kControlNoPart, kControlSizeTag,
                sizeof(kControlSizeSmall), (void *) kControlSizeLarge);
    }        
    
    /*
     * Update the control values before we draw.
     */
    windowRef  = GetControlOwner (macScrollPtr->sbHandle);
    UpdateControlValues(macScrollPtr);
    
    if (macScrollPtr->macFlags & ACTIVE) {
        Draw1Control(macScrollPtr->sbHandle);
        if (macScrollPtr->macFlags & DRAW_GROW) {
            DrawGrowIcon(windowRef);
        }
    } else {
        HiliteControl (macScrollPtr->sbHandle, 255 );
        Draw1Control(macScrollPtr->sbHandle);
        if (macScrollPtr->macFlags & DRAW_GROW) {
            DrawGrowIcon(windowRef);
            Tk_Fill3DRectangle(tkwin, Tk_WindowId(tkwin), scrollPtr->bgBorder,
                Tk_Width(tkwin) - 13, Tk_Height(tkwin) - 13,
                Tk_Width(tkwin), Tk_Height(tkwin),
                0, TK_RELIEF_FLAT);
        }
    }
    
    SetGWorld(saveWorld, saveDevice);
     
    done:
    scrollPtr->flags &= ~REDRAW_PENDING;
}

/*
 *----------------------------------------------------------------------
 *
 * TkpConfigureScrollbar --
 *
 *        This procedure is called after the generic code has finished
 *        processing configuration options, in order to configure
 *        platform specific options.
 *
 * Results:
 *        None.
 *
 * Side effects:
 *        None.
 *
 *----------------------------------------------------------------------
 */

void
TkpConfigureScrollbar(scrollPtr)
    register TkScrollbar *scrollPtr;        /* Information about widget;  may or
                                             * may not already have values for
                                             * some fields. */
{
}

/*
 *----------------------------------------------------------------------
 *
 * TkpComputeScrollbarGeometry --
 *
 *        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.
 *
 *----------------------------------------------------------------------
 */

void
TkpComputeScrollbarGeometry(
    register TkScrollbar *scrollPtr)        /* Scrollbar whose geometry may
                                             * have changed. */
{
    MacScrollbar *macScrollPtr = (MacScrollbar *) scrollPtr;
    int width, fieldLength, adjust = 0;

    if (scrollPtr->highlightWidth < 0) {
        scrollPtr->highlightWidth = 0;
    }
    scrollPtr->inset = scrollPtr->highlightWidth + scrollPtr->borderWidth;
    width = (scrollPtr->vertical) ? Tk_Width(scrollPtr->tkwin)
            : Tk_Height(scrollPtr->tkwin);
    scrollPtr->arrowLength = width - 2*scrollPtr->inset + 1;
    fieldLength = (scrollPtr->vertical ? Tk_Height(scrollPtr->tkwin)
            : Tk_Width(scrollPtr->tkwin))
            - 2*(scrollPtr->arrowLength + scrollPtr->inset);
    if (fieldLength < 0) {
        fieldLength = 0;
    }
    scrollPtr->sliderFirst = fieldLength * scrollPtr->firstFraction;
    scrollPtr->sliderLast = fieldLength * scrollPtr->lastFraction;

    /*
     * 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
            + MIN_SLIDER_LENGTH)) {
        scrollPtr->sliderLast = scrollPtr->sliderFirst + MIN_SLIDER_LENGTH;
    }
    if (scrollPtr->sliderLast > fieldLength) {
        scrollPtr->sliderLast = fieldLength;
    }
    scrollPtr->sliderFirst += scrollPtr->arrowLength + scrollPtr->inset;
    scrollPtr->sliderLast += scrollPtr->arrowLength + scrollPtr->inset;

    /*
     * 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) {
        if ((macScrollPtr->macFlags & AUTO_ADJUST) &&
            (macScrollPtr->macFlags & (FLUSH_RIGHT|FLUSH_LEFT))) {
            adjust--;
        }
        Tk_GeometryRequest(scrollPtr->tkwin,
            scrollPtr->width + 2*scrollPtr->inset + adjust,
            2*(scrollPtr->arrowLength + scrollPtr->borderWidth
            + scrollPtr->inset));
    } else {
        if ((macScrollPtr->macFlags & AUTO_ADJUST) &&
            (macScrollPtr->macFlags & (FLUSH_TOP|FLUSH_BOTTOM))) {
            adjust--;
        }
        Tk_GeometryRequest(scrollPtr->tkwin,
            2*(scrollPtr->arrowLength + scrollPtr->borderWidth
            + scrollPtr->inset), scrollPtr->width + 2*scrollPtr->inset + adjust);
    }
    Tk_SetInternalBorder(scrollPtr->tkwin, scrollPtr->inset);
}

/*
 *----------------------------------------------------------------------
 *
 * TkpDestroyScrollbar --
 *
 *        Free data structures associated with the scrollbar control.
 *
 * Results:
 *        None.
 *
 * Side effects:
 *        None.
 *
 *----------------------------------------------------------------------
 */

void
TkpDestroyScrollbar(
    TkScrollbar *scrollPtr)        /* Scrollbar to destroy. */
{
    MacScrollbar *macScrollPtr = (MacScrollbar *)scrollPtr;

    if (macScrollPtr->sbHandle != NULL) {
        if (!(macScrollPtr->macFlags & IN_MODAL_LOOP)) {
            DisposeControl(macScrollPtr->sbHandle);
            macScrollPtr->sbHandle = NULL;
        }
    }
    macScrollPtr->macFlags |= ALREADY_DEAD;
}

/*
 *--------------------------------------------------------------
 *
 * TkpScrollbarPosition --
 *
 *        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.
 *
 *--------------------------------------------------------------
 */

int
TkpScrollbarPosition(
    TkScrollbar *scrollPtr,        /* Scrollbar widget record. */
    int x, int y)                /* Coordinates within scrollPtr's
                                 * window. */
{
    MacScrollbar *macScrollPtr = (MacScrollbar *) scrollPtr;
    GWorldPtr destPort;
    int length, width, tmp, inactive = false;
    ControlPartCode part;
    Point where;
    Rect bounds;
    int  x0, y0;

    x0 = x;
    y0 = y;

    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 < scrollPtr->inset) || (x >= (width - scrollPtr->inset))
            || (y < scrollPtr->inset) || (y >= (length - scrollPtr->inset))) {
        return OUTSIDE;
    }

    /*
     * All of the calculations in this procedure mirror those in
     * DisplayScrollbar.  Be sure to keep the two consistent.  On the 
     * Macintosh we use the OS call TestControl to do this mapping.
     * For TestControl to work, the scrollbar must be active and must
     * be in the current port.
     */

    destPort = TkMacOSXGetDrawablePort(Tk_WindowId(scrollPtr->tkwin));
    SetGWorld(destPort, NULL);
    UpdateControlValues(macScrollPtr);
    if ( GetControlHilite(macScrollPtr->sbHandle) == 255 ) {
        inactive = true;
        HiliteControl(macScrollPtr->sbHandle, 0 );
    }

    TkMacOSXWinBounds((TkWindow *) scrollPtr->tkwin, &bounds);                
    where.h = x0 + bounds.left;
    where.v = y0 + bounds.top;
    part = TestControl(((MacScrollbar *) scrollPtr)->sbHandle, where);
    if (inactive) {
        HiliteControl(macScrollPtr->sbHandle, 255 );
    }
    switch (part) {
        case kControlUpButtonPart:
            return TOP_ARROW;
        case kControlPageUpPart:
            return TOP_GAP;
        case kControlIndicatorPart:
            return SLIDER;
        case kControlPageDownPart:
            return BOTTOM_GAP;
        case kControlDownButtonPart:
            return BOTTOM_ARROW;
        default:
            return OUTSIDE;
    }
}

/*
 *--------------------------------------------------------------
 *
 * ThumbActionProc --
 *
 *        Callback procedure used by the Macintosh toolbox call
 *        TrackControl.  This call is used to track the thumb of
 *        the scrollbar.  Unlike the ScrollbarActionProc function
 *        this function is called once and basically takes over
 *        tracking the scrollbar from the control.  This is done
 *        to avoid conflicts with what the control plans to draw.
 *
 * Results:
 *        None.
 *
 * Side effects:
 *        May change the display.
 *
 *--------------------------------------------------------------
 */

static pascal void
ThumbActionProc()
{
    register TkScrollbar *scrollPtr = activeScrollPtr;
    register MacScrollbar *macScrollPtr = (MacScrollbar *) activeScrollPtr;
    Tcl_DString cmdString;
    int origValue, trackBarPin;
    double thumbWidth, newFirstFraction, trackBarSize;
    char valueString[40];
    Point currentPoint = { 0, 0 };
    Rect trackRect;
    Tcl_Interp *interp;
    MouseTrackingResult trackingResult;
    OSErr err;
    
    if (scrollPtr == NULL) {
        return;
    }

    Tcl_DStringInit(&cmdString);
    
    /*
     * First compute values that will remain constant during the tracking
     * of the thumb.  The variable trackBarSize is the length of the scrollbar
     * minus the 2 arrows and half the width of the thumb on both sides
     * (3 * arrowLength).  The variable trackBarPin is the lower starting point
     * of the drag region.
     *
     * Note: the arrowLength is equal to the thumb width of a Mac scrollbar.
     */

    origValue = GetControlValue(macScrollPtr->sbHandle);
    GetControlBounds(macScrollPtr->sbHandle, &trackRect);
    if (scrollPtr->vertical == true) {
        trackBarSize = (double) (trackRect.bottom - trackRect.top
            - (scrollPtr->arrowLength * 3));
        trackBarPin = trackRect.top + scrollPtr->arrowLength
            + (scrollPtr->arrowLength / 2);
        InsetRect(&trackRect, -25, -113);
        
    } else {
        trackBarSize = (double) (trackRect.right - trackRect.left
            - (scrollPtr->arrowLength * 3));
        trackBarPin = trackRect.left + scrollPtr->arrowLength
            + (scrollPtr->arrowLength / 2);
        InsetRect(&trackRect, -113, -25);
    }

    /*
     * Track the mouse while the button is held down.  If the mouse is moved,
     * we calculate the value that should be passed to the "command" part of
     * the scrollbar.
     */

    do {
        err = TrackMouseLocationWithOptions(NULL,
                kTrackMouseLocationOptionDontConsumeMouseUp,
                kEventDurationForever,
                &currentPoint,
                NULL,
                &trackingResult);
            
        if ((err==noErr) 
                && ((trackingResult == kMouseTrackingMouseDragged)
                || (trackingResult == kMouseTrackingMouseMoved))) {
        /*
         * Calculating this value is a little tricky.  We need to calculate a
         * value for where the thumb would be in a Motif widget (variable
         * thumb).  This value is what the "command" expects and is what will
         * be resent to the scrollbar to update its value.
         */
            thumbWidth = scrollPtr->lastFraction - scrollPtr->firstFraction;
            if (PtInRect(currentPoint, &trackRect)) {
                if (scrollPtr->vertical == true) {
                    newFirstFraction =  (1.0 - thumbWidth) *
                        ((double) (currentPoint.v - trackBarPin) / trackBarSize);
                } else {
                    newFirstFraction =  (1.0 - thumbWidth) *
                        ((double) (currentPoint.h - trackBarPin) / trackBarSize);
                }
            } else {
                newFirstFraction = ((double) origValue / MAX_SCROLLBAR_DVALUE)
                   * (1.0 - thumbWidth);
            }
            sprintf(valueString, "%g", newFirstFraction);
            Tcl_DStringSetLength(&cmdString, 0);
            Tcl_DStringAppend(&cmdString, scrollPtr->command,
                scrollPtr->commandSize);
            Tcl_DStringAppendElement(&cmdString, "moveto");
            Tcl_DStringAppendElement(&cmdString, valueString);
            interp = scrollPtr->interp;
            Tcl_Preserve((ClientData) interp);
            Tcl_GlobalEval(interp, cmdString.string);
            Tcl_Release((ClientData) interp);
            Tcl_DStringSetLength(&cmdString, 0);
            Tcl_DStringAppend(&cmdString, "update idletasks",
                strlen("update idletasks"));
            Tcl_Preserve((ClientData) interp);
            Tcl_GlobalEval(interp, cmdString.string);
            Tcl_Release((ClientData) interp);
        }
    } while ((err==noErr) && trackingResult!=kMouseTrackingMouseReleased );

    Tcl_DStringFree(&cmdString);
    return;
}

/*
 *--------------------------------------------------------------
 *
 * ScrollbarActionProc --
 *
 *        Callback procedure used by the Macintosh toolbox call
 *        TrackControl.  This call will update the display while
 *        the scrollbar is being manipulated by the user.
 *
 * Results:
 *        None.
 *
 * Side effects:
 *        May change the display.
 *
 *--------------------------------------------------------------
 */

static pascal void
ScrollbarActionProc(
    ControlRef theControl,         /* Handle to scrollbat control */
    ControlPartCode partCode)        /* Part of scrollbar that was "hit" */
{
    TkScrollbar *scrollPtr = (TkScrollbar *) GetControlReference(theControl);
    Tcl_DString cmdString;
    
    Tcl_DStringInit(&cmdString);
    Tcl_DStringAppend(&cmdString, scrollPtr->command,
            scrollPtr->commandSize);

    if ( partCode == kControlUpButtonPart ||
         partCode == kControlDownButtonPart ) {
        Tcl_DStringAppendElement(&cmdString, "scroll");
        Tcl_DStringAppendElement(&cmdString,
                (partCode == kControlUpButtonPart ) ? "-1" : "1");
        Tcl_DStringAppendElement(&cmdString, "unit");
    } else if (partCode == kControlPageUpPart || partCode == kControlPageDownPart ) {
        Tcl_DStringAppendElement(&cmdString, "scroll");
        Tcl_DStringAppendElement(&cmdString,
                (partCode == kControlPageUpPart ) ? "-1" : "1");
        Tcl_DStringAppendElement(&cmdString, "page");
    }
    Tcl_Preserve((ClientData) scrollPtr->interp);
    Tcl_DStringAppend(&cmdString, "; update idletasks",
        strlen("; update idletasks"));
    Tcl_GlobalEval(scrollPtr->interp, cmdString.string);
    Tcl_Release((ClientData) scrollPtr->interp);

    Tcl_DStringFree(&cmdString);
}

/*
 *--------------------------------------------------------------
 *
 * ScrollbarBindProc --
 *
 *        This procedure is invoked when the default <ButtonPress>
 *        binding on the Scrollbar bind tag fires.
 *
 * Results:
 *        None.
 *
 * Side effects:
 *        The event enters a modal loop.
 *
 *--------------------------------------------------------------
 */

static int
ScrollbarBindProc(
    ClientData clientData,        /* Not used. */
    Tcl_Interp *interp,           /* Interp with binding. */
    XEvent *eventPtr,             /* X event that triggered binding. */
    Tk_Window tkwin,              /* Target window for event. */
    KeySym keySym)                /* The KeySym if a key event. */
{
    TkWindow *winPtr = (TkWindow*)tkwin;
    TkScrollbar *scrollPtr = (TkScrollbar *) winPtr->instanceData;
    MacScrollbar *macScrollPtr = (MacScrollbar *) winPtr->instanceData;

    Tcl_Preserve((ClientData)scrollPtr);
    macScrollPtr->macFlags |= IN_MODAL_LOOP;
    
    if (eventPtr->type == ButtonPress) {
            Point where;
            Rect bounds;
            int part, x, y, dummy;
            unsigned int state;
        CGrafPtr saveWorld;
        GDHandle saveDevice;
        GWorldPtr destPort;
        Window window;

        /*
         * To call Macintosh control routines we must have the port
         * set to the window containing the control.  We will then test
         * which part of the control was hit and act accordingly.
         */
        destPort = TkMacOSXGetDrawablePort(Tk_WindowId(scrollPtr->tkwin));
        GetGWorld(&saveWorld, &saveDevice);
        SetGWorld(destPort, NULL);
        TkMacOSXSetUpClippingRgn(Tk_WindowId(scrollPtr->tkwin));

        TkMacOSXWinBounds((TkWindow *) scrollPtr->tkwin, &bounds);                
            where.h = eventPtr->xbutton.x + bounds.left;
            where.v = eventPtr->xbutton.y + bounds.top;
        part = TestControl(macScrollPtr->sbHandle, where);
        if (part == kControlIndicatorPart && scrollPtr->jump == false) {
            /*
             * Case 1: In thumb, no jump scrolling.  Call track control
             * with the thumb action proc which will do most of the work.
             * Set the global activeScrollPtr to the current control
             * so the callback may have access to it.
             */
            activeScrollPtr = scrollPtr;
            part = TrackControl(macScrollPtr->sbHandle, where,
                    (ControlActionUPP) thumbActionProc);
            activeScrollPtr = NULL;
        } else if (part == kControlIndicatorPart) {
            /*
             * Case 2: in thumb with jump scrolling.  Call TrackControl
             * with a NULL action proc.  Use the new value of the control
             * to set update the control.
             */
            part = TrackControl(macScrollPtr->sbHandle, where, NULL);
            if (part == kControlIndicatorPart) {
                    double newFirstFraction, thumbWidth;
                Tcl_DString cmdString;
                char valueString[TCL_DOUBLE_SPACE];

                /*
                 * The following calculation takes the new control
                 * value and maps it to what Tk needs for its variable
                 * thumb size representation.
                 */
                thumbWidth = scrollPtr->lastFraction
                     - scrollPtr->firstFraction;
                newFirstFraction = (1.0 - thumbWidth) *
                    ((double) GetControlValue(macScrollPtr->sbHandle) / MAX_SCROLLBAR_DVALUE);
                sprintf(valueString, "%g", newFirstFraction);

                Tcl_DStringInit(&cmdString);
                Tcl_DStringAppend(&cmdString, scrollPtr->command,
                        strlen(scrollPtr->command));
                Tcl_DStringAppendElement(&cmdString, "moveto");
                Tcl_DStringAppendElement(&cmdString, valueString);
                Tcl_DStringAppend(&cmdString, "; update idletasks",
                        strlen("; update idletasks"));
                
                interp = scrollPtr->interp;
                Tcl_Preserve((ClientData) interp);
                Tcl_GlobalEval(interp, cmdString.string);
                Tcl_Release((ClientData) interp);
                Tcl_DStringFree(&cmdString);                
            }
        } else if (part != 0) {
            /*
             * Case 3: in any other part of the scrollbar.  We call
             * TrackControl with the scrollActionProc which will do
             * most all the work.
             */
            TrackControl(macScrollPtr->sbHandle, where, scrollActionProc);
            HiliteControl(macScrollPtr->sbHandle, 0);
        }
        
        /*
         * The TrackControl call will "eat" the ButtonUp event.  We now
         * generate a ButtonUp event so Tk will unset implicit grabs etc.
         */
        GetMouse(&where);
        XQueryPointer(NULL, None, &window, &window, &x,
            &y, &dummy, &dummy, &state);
        window = Tk_WindowId(scrollPtr->tkwin);
        TkGenerateButtonEvent(x, y, window, state);

        SetGWorld(saveWorld, saveDevice);
    }

    if (macScrollPtr->sbHandle && (macScrollPtr->macFlags & ALREADY_DEAD)) {
        DisposeControl(macScrollPtr->sbHandle);
        macScrollPtr->sbHandle = NULL;
    }
    macScrollPtr->macFlags &= ~IN_MODAL_LOOP;
    Tcl_Release((ClientData)scrollPtr);
    
    return TCL_OK;
}

/*
 *--------------------------------------------------------------
 *
 * 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 clientData,        /* Information about window. */
    XEvent *eventPtr)             /* Information about event. */
{
    TkScrollbar *scrollPtr = (TkScrollbar *) clientData;
    MacScrollbar *macScrollPtr = (MacScrollbar *) clientData;

    if (eventPtr->type == UnmapNotify) {
        TkMacOSXSetScrollbarGrow((TkWindow *) scrollPtr->tkwin, false);
    } else if (eventPtr->type == ActivateNotify) {
        macScrollPtr->macFlags |= ACTIVE;
        TkScrollbarEventuallyRedraw((ClientData) scrollPtr);
    } else if (eventPtr->type == DeactivateNotify) {
        macScrollPtr->macFlags &= ~ACTIVE;
        TkScrollbarEventuallyRedraw((ClientData) scrollPtr);
    } else {
        TkScrollbarEventProc(clientData, eventPtr);
    }
}

/*
 *--------------------------------------------------------------
 *
 * UpdateControlValues --
 *
 *        This procedure updates the Macintosh scrollbar control
 *        to display the values defined by the Tk scrollbar.
 *
 * Results:
 *        None.
 *
 * Side effects:
 *        The Macintosh control is updated.
 *
 *--------------------------------------------------------------
 */

static void
UpdateControlValues(
    MacScrollbar *macScrollPtr)                /* Scrollbar data struct. */
{
    TkScrollbar *scrollPtr = (TkScrollbar *) macScrollPtr;
    Tk_Window tkwin = scrollPtr->tkwin;
    MacDrawable * macDraw = (MacDrawable *) Tk_WindowId(scrollPtr->tkwin);
    WindowRef windowRef  = GetControlOwner(macScrollPtr->sbHandle);
    double middle;
    SInt32 viewSize;
    int flushRight = false;
    int flushBottom = false;
    Rect contrlRect, portRect;
    UInt8 contrlHilite;

    /*
     * We can't use the Macintosh commands SizeControl and MoveControl as these
     * calls will also cause a redraw which in our case will also cause
     * flicker.  To avoid this we adjust the control record directly.  The
     * Draw1Control command appears to just draw where ever the control says to
     * draw so this seems right.
     *
     * NOTE: changing the control record directly may not work when
     * Apple releases the Copland version of the MacOS (or when hell is cold).
     */
     
    contrlRect.left   = macDraw->xOff + scrollPtr->inset;
    contrlRect.top    = macDraw->yOff + scrollPtr->inset;
    contrlRect.right  = macDraw->xOff + Tk_Width(tkwin) - scrollPtr->inset;
    contrlRect.bottom = macDraw->yOff + Tk_Height(tkwin) - scrollPtr->inset;
        
    SetControlBounds(macScrollPtr->sbHandle, &contrlRect );
    
    /*
     * To make Tk applications look more like Macintosh applications without 
     * requiring additional work by the Tk developer we do some cute tricks.
     * The first trick plays with the size of the widget to get it to overlap
     * with the side of the window by one pixel (we don't do this if the placer
     * is the geometry manager).  The second trick shrinks the scrollbar if it
     * it covers the area of the grow region ao the scrollbar can also draw
     * the grow region if need be.
     */
    if (!strcmp(macDraw->winPtr->geomMgrPtr->name, "place")) {
        macScrollPtr->macFlags &= ~AUTO_ADJUST;
    } else {
        macScrollPtr->macFlags |= AUTO_ADJUST;
    }
    GetPortBounds ( GetWindowPort ( windowRef ), &portRect );
    if ( portRect.left == contrlRect.left ) {
        if (macScrollPtr->macFlags & AUTO_ADJUST) {
            contrlRect.left--;
            SetControlBounds ( macScrollPtr->sbHandle, &contrlRect );
        }
        if (!(macScrollPtr->macFlags & FLUSH_LEFT)) {
            macScrollPtr->macFlags |= FLUSH_LEFT;
            if (scrollPtr->vertical) {
                TkpComputeScrollbarGeometry(scrollPtr);
            }
        }
    } else if (macScrollPtr->macFlags & FLUSH_LEFT) {
        macScrollPtr->macFlags &= ~FLUSH_LEFT;
        if (scrollPtr->vertical) {
            TkpComputeScrollbarGeometry(scrollPtr);
        }
    }
    
    if (portRect.top == contrlRect.top) {
        if (macScrollPtr->macFlags & AUTO_ADJUST) {
            contrlRect.top--;
        }
        if (!(macScrollPtr->macFlags & FLUSH_TOP)) {
            macScrollPtr->macFlags |= FLUSH_TOP;
            if (! scrollPtr->vertical) {
                TkpComputeScrollbarGeometry(scrollPtr);
            }
        }
    } else if (macScrollPtr->macFlags & FLUSH_TOP) {
        macScrollPtr->macFlags &= ~FLUSH_TOP;
        if (! scrollPtr->vertical) {
            TkpComputeScrollbarGeometry(scrollPtr);
        }
    }
        
    if (portRect.right == contrlRect.right) {
        flushRight = true;
        if (macScrollPtr->macFlags & AUTO_ADJUST) {
            contrlRect.right++;
        }
        if (!(macScrollPtr->macFlags & FLUSH_RIGHT)) {
            macScrollPtr->macFlags |= FLUSH_RIGHT;
            if (scrollPtr->vertical) {
                TkpComputeScrollbarGeometry(scrollPtr);
            }
        }
    } else if (macScrollPtr->macFlags & FLUSH_RIGHT) {
        macScrollPtr->macFlags &= ~FLUSH_RIGHT;
        if (scrollPtr->vertical) {
            TkpComputeScrollbarGeometry(scrollPtr);
        }
    }
        
    if (portRect.bottom == contrlRect.bottom) {
        flushBottom = true;
        if (macScrollPtr->macFlags & AUTO_ADJUST) {
            contrlRect.bottom++;
        }
        if (!(macScrollPtr->macFlags & FLUSH_BOTTOM)) {
            macScrollPtr->macFlags |= FLUSH_BOTTOM;
            if (! scrollPtr->vertical) {
                TkpComputeScrollbarGeometry(scrollPtr);
            }
        }
    } else if (macScrollPtr->macFlags & FLUSH_BOTTOM) {
        macScrollPtr->macFlags &= ~FLUSH_BOTTOM;
        if (! scrollPtr->vertical) {
            TkpComputeScrollbarGeometry(scrollPtr);
        }
    }

    /*
     * If the scrollbar is flush against the bottom right hand corner then
     * it may need to draw the grow region for the window so we let the
     * wm code know about this scrollbar.  We don't actually draw the grow
     * region, however, unless we are currently resizable.
     */
    macScrollPtr->macFlags &= ~DRAW_GROW;
    if (flushBottom && flushRight) {
        TkMacOSXSetScrollbarGrow((TkWindow *) tkwin, true);
        if (TkMacOSXResizable(macDraw->toplevel->winPtr)) {
            if (scrollPtr->vertical) {
                contrlRect.bottom -= 14;
            } else {
                contrlRect.right -= 14;
            }
            macScrollPtr->macFlags |= DRAW_GROW;
        }
    } else {
        TkMacOSXSetScrollbarGrow((TkWindow *) tkwin, false);
    }
    
    /*
     * Given the Tk parameters for the fractions of the start and
     * end of the thumb, the following calculation determines the
     * location for the fixed sized Macintosh thumb.
     */
    middle = scrollPtr->firstFraction / (scrollPtr->firstFraction +
            (1.0 - scrollPtr->lastFraction));
    
    viewSize = (SInt32) ((scrollPtr->lastFraction - scrollPtr->firstFraction) 
            * MAX_SCROLLBAR_DVALUE
	    /(1 - (scrollPtr->lastFraction - scrollPtr->firstFraction)));
    
    SetControlViewSize(macScrollPtr->sbHandle,viewSize);
    SetControlValue(macScrollPtr->sbHandle, 
            (short) (middle * MAX_SCROLLBAR_VALUE) );
    contrlHilite = GetControlHilite(macScrollPtr->sbHandle);
    SetControlMinimum(macScrollPtr->sbHandle, 0);
    if ( contrlHilite == 0 || contrlHilite == 255) {
        if (scrollPtr->firstFraction == 0.0 &&
                scrollPtr->lastFraction == 1.0) {
            SetControlMinimum(macScrollPtr->sbHandle, MAX_SCROLLBAR_VALUE);
        } else {
            HiliteControl(macScrollPtr->sbHandle, 0);
        }
    }
    
    if ( !IsControlVisible (macScrollPtr -> sbHandle) ) {
        SetControlVisibility(macScrollPtr->sbHandle,TRUE,FALSE);
    }
}