Apple Developer Connection 1998 Fall: Game Toolkit/Disc.iso/SDKs/PCI Driver Development Kit/• Tools/Utility/DisplayNameRegistry 950412/Src/TwistDownList.c

C/C++ Source or Header | 1997-02-27 | 66.2 KB | 2,194 lines | [TEXT/MPCC]

/*                                    TwistDownList.c                                */
/*
 * List In A List Sample
 * TwistDownList.c
 * Copyright © 1993-94 Apple Computer Inc. All rights reserved.
 *
 * TwistDownList manages all aspects of the "twist-down" list, a one-column text
 * list where each row contains a triangular button. The button may be in one of
 * two states: closed and opened. When opened, sub-elements to this row are
 * displayed. The twist-down list is generally based on code from NewsWatcher
 * by Steve Falkenburg, but Steve says that the code was originally written by
 * John Norstad.
 *
 * Applications must provide a LDEF stub resource by adding the following (or
 * something equivalent) to the resource definition file:
 *        #ifndef LDEF_Stub
 *        #define LDEF_Stub    1024
 *        #endif
 *        type 'LDEF' {
 *        unsigned hex longint = $41FA0006;    //    lea        pc+8,a0    ; a0 -> ProcPtr
 *        unsigned hex int = $2050;            //    movea.l    (a0),a0    ; a0 -> LDEF
 *        unsigned hex int = $4ED0;            //    jmp        (a0)    ; jump to it
 *        unsigned hex longint = 0;            //    dc.l    0        ; LDEF ProcPtr
 *        };
 *        resource 'LDEF' (LDEF_Stub, "Stub LDEF", preload, locked) { };
 *
 * Because of the way that the callback LDEF is managed, TwistDownList.c must be
 * in the application's root segment. If this is inappropriate, the segement
 * resource must be marked "preload" and "locked" -- otherwise, your program will
 * crash. (Note that this applies only to 68000 code.)
 */
#include <stdio.h>
#include "TwistDownList.h"
#include "Palettes.h"
#include "IntlResources.h"
#include "Script.h"
#include "TextUtils.h"
#include "SegLoad.h"
#include "FixMath.h"
#include "ToolUtils.h"
#include "Gestalt.h"
#include "Resources.h"
#include "Packages.h"
#ifdef __powerc
/*
 * PowerPC System area locations in "Get" and "Set" functions. They are
 * defined in LowMem.h
 */
#include <LowMem.h>
#else
#ifdef MPW
/*
 * MPW requires a reference to a low memory global to set hiliting
 * Think C and MetroWorks includes SysEqu.h in the default MacHeaders file.
 */
#include <SysEqu.h>
#endif
#endif

#define UNUSED(what) do {    \
            what;            \
        } while (0)

#ifndef MONOCHROME_FILL
#define MONOCHROME_FILL    0
#endif

#define LIST    (**theList)
/*
 * A common List Selection flag variation that equates Shift and Command keys.
 */
#define SELECTION_FLAGS    \
    (lUseSense | lNoRect | lNoExtend | lNoNilHilite | lDoVAutoscroll)
/*
 * SELECTION_FLAGS, by default, allows a single list cell to be selected.
 */
#ifndef SELECTION_FLAGS
#define SELECTION_FLAGS (lOnlyOne | lNoNilHilite | lDoVAutoscroll)
#endif

enum {
    kScrollBarWidth            = 16,
    kScrollBarOffset        = kScrollBarWidth - 1,
    kActiveControl            = 0,                    /* Normal button, no hilite    */
    kDisabledControl        = 255,                    /* Disabled button hilite    */
    kZeroIndent                = 4                        /* Indent if scrollbar == 0    */
};
/*
 * This is a nominal value for the maximum cell width. It might be better as a
 * user-settable parameter.
 */
#define kMaxHorizontalScroll    (CharWidth('M') * 255)

/*
 * kAnimationDelay is the number of ticks to display the intermediate
 * "twisting" glyph.
 */
#define kAnimationDelay        3L
/*
 * The triangle gap parameters define the amount of space to display to the
 * left and right of the twist-down triangle. The "outside gap" is to the left
 * on Roman-alphabet scripts and on the right on Hebrew or Arabic scripts.
 * The default values are suitable for small font sizes, but could be increased
 * for large sizes.
 */
#define kTriangleOutsideGap        (1)                    /* From margin to button    */
#define kTriangleInsideGap        (2)                    /* From button to text        */
#define kScrollBarWidth            (16)                /* Width of a scroll bar    */

/*
 * Parameters for the print handler.
 */
#define kPrintoutHeaderFont        "\pHelvetica"
#define kPrintoutHeaderFontSize    9
#define kPrintoutHeaderGap        4
#define kPrintoutHeaderStyle    bold

/*
 * The List's userHandle contains our private context information. The PolyHandles
 * are used to draw the "triangle" buttons. Note that they are drawn to the list
 * cell height. When it changes, the triangles will be reconstructed. The fontSize,
 * fontNumber, and isLeftJustify variables are used to draw the list cell content.
 */
struct TwistDownPrivateRecord {
        TwistDownDrawProc    drawProc;                /* This draws the cell data    */
        PolyHandle            openTriangle;            /* The "expanded" button    */
        PolyHandle            closedTriangle;            /* The "closed" button        */
        PolyHandle            intermediateTriangle;    /* The "expanding" button    */
        ControlHandle        hScroll;                /* List's horiz. scrollbar    */
        short                tabIndent;                /* NewTwistDownList param    */
        short                fontSize;                /* for TextSize                */
        short                fontNumber;                /* for TextFont                */
        Boolean                canHiliteSelection;        /* TRUE if hilite ok        */
        Boolean                isLeftJustify;            /* GetSysJust value            */
        short                triangleWidth;            /* Twist-down button width    */
};
typedef struct TwistDownPrivateRecord    TwistDownPrivateRecord,
        *TwistDownPrivatePtr, **TwistDownPrivateHdl;

/*
 * The de-referenced private data record is too long to type each time it appears
 * so it will be defined by the PRIVATE macro.
 */
#define PRIVATE            (**((TwistDownPrivateHdl) (LIST.userHandle)))
/*
 * These macros simplify access to the flag word in the list element.
 */
#define SetTDFlag(elementHdl, mask)        ((**elementHdl).flag |= (mask))
#define ClearTDFlag(elementHdl, mask)    ((**elementHdl).flag &= ~(mask))
#define InvertTDFlag(elementHdl, mask)    ((**elementHdl).flag ^= (mask))
#define TestTDFlag(elementHdl, mask)    (((**elementHdl).flag & (mask)) != 0)

#define SIBLING            (*twistDownSiblingSetPtr)

/*
 * The proper way to build a compiled-in LDEF is to plug a transfer address into a
 * stub code resource. The StubRecord must track any changes in the LDEF resource.
 */
#ifdef __powerc
#pragma options align=mac68k
#endif
struct StubRecord {
    long            lea;            /*    Lea            (pc)+8,a0                    */
    short            movea;            /*    Movea.l        (a0),a0                        */
    short            jmp;            /*    jmp            (a0)                        */
    ListDefUPP        ldefAddress;    /*    dc.l        0                            */
};
typedef struct StubRecord    **StubHandle;
#ifdef __powerc
#pragma options align=reset
#endif

/*
 * Local (private) functions.
 */
/*
 * Dispose of a PolyHandle. This must be a macro. The argument
 * may not have side-effects.
 */
#define ForgetPoly(thePoly) do {        \
        if (thePoly != NULL) {             \
            KillPoly(thePoly);            \
            thePoly = NULL;                \
        }                                \
    } while (0)
#define height(r)        ((r).bottom - (r).top)
#define width(r)        ((r).right - (r).left)

static short                CountVisibleElements(
        TwistDownHdl            twistDownHandle
    );
static void                 ClearSelectedElementBit(
        TwistDownHdl            twistDownHandle
    );
static void                    CopySelectionStateToList(
        ListHandle                theList,
        short                    selectedRow
    );
static void                    SetElementsInList(
        ListHandle                theList,
        TwistDownHdl            twistDownHandle,
        Cell                    *currentCell
    );
static pascal void            TwistDownLDEF(
        short                    listMessage,
        Boolean                    listSelect,
        Rect                    *listRect,
        Cell                    listCell,
        short                    listDataOffset,
        short                    listDataLen,
        ListHandle                listHandle
    );
static void                    DrawTriangle(
        PolyHandle                polyHandle,
        Point                    polyPoint,
        Boolean                    isSelected
    );
static pascal void            DefaultTwistDownDrawProc(
        ListHandle                theList,            /* The list itself            */
        TwistDownPtr            twistDownPtr,        /* Locked data handle        */
        const Rect                *viewRect            /* Draw in this area        */
    );

/*
 * Horizontal scrollbar stuff
 */
static void                    AdjustHorizontalScrollbar(
        ListHandle                theList
    );
static pascal void            ScrollTwistDownActionProc(
        register ControlHandle    theControl,
        short                    partCode
    );
static void                    ScrollTwistDownList(
        register ControlHandle    theControl
    );

static void                    pstrcpy(
        StringPtr                dst,
        ConstStr255Param        src
    );
static void                    pstrcat(
        StringPtr                dst,
        ConstStr255Param        src
    );

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * NewTwistDownList
 *
 * Create a twist-down list. Before calling, you must set the port to the current
 * window and specify the font and font size that is to be used to draw the list.
 * NewTwistDownList creates an empty one-column list with vertical and horizontal
 * scroll bars. Only one item may be selected at a time; but this could be changed
 * by the application without difficulty. The scrollbars are managed internally.
 *
 * Note: unlike the previous release of TwistDownList, the viewRect does not
 * include the scroll bars. For a fullscreen list, do the following:
 *        viewRect = FrontWindow()->portRect;
 *        viewRect.right -= kScrollBarWidth;
 *        viewRect.bottom -= kScrollBarWidth;
 *
 * The tabIndent parameter should be set to the amount to indent successive levels
 * (zero means no indentation). Setting it to the widMax value from the current
 * font seems reasonable.
 *
 * canHiliteSelection should be TRUE for normal selection (the selection is
 * hilited). It should be FALSE if you want to supress selection. Because
 * hirearchical lists often "select" by revealing a sub-topic, this may be
 * more reasonable in many cases.
 *
 * isLeftJustify should be set TRUE for systems using the Roman alphabet. It would
 * be set FALSE for right-to-left languages such as Arabic and Hebrew. It is used
 * to configure the direction of the buttons and the location of text within
 * the displayed list cell.
 *
 * We manage the horizontal scrollbar by some private trickery -- this lets the
 * list pane be smaller than the amount of text to be displayed.
 */
pascal ListHandle
NewTwistDownList(
        const Rect                *viewRect,
        TwistDownDrawProc        drawProc,
        unsigned short            tabIndent,
        Boolean                    canHiliteSelection,
        Boolean                    isLeftJustify,
        Boolean                    hasGrowBox
    )
{
        register TwistDownPrivatePtr    privatePtr;
        ListHandle                theList;
        short                    listHeight;
        Point                    cellSize;
        Rect                    dataBounds;
        Rect                    listRect;
        FontInfo                info;
        short                    listFontHeight;
        GrafPtr                    currentPort;
        ListDefUPP                listDefProc;
        StubHandle                stubHandle;

        theList = NULL;
        GetPort(¤tPort);
        GetFontInfo(&info);
        listFontHeight = info.ascent + info.descent + info.leading;
        /*
         * Define the list drawing area. If the list viewRect.bottom
         * is less than the portRect.bottom, adjust the list area height
         * integral number of rows will be drawn. If equal, the list
         * area abuts the bottom of the display window and we shouldn't
         * change the bottom or the scroll bars will look wierd.
         */
        listRect = *viewRect;
        SetPt(&cellSize, width(listRect), listFontHeight);
        if ((listRect.bottom + kScrollBarWidth) < currentPort->portRect.bottom) {
            listHeight = height(listRect);
            listHeight -= (listHeight % listFontHeight);
            listRect.bottom = listRect.top + listHeight;
        }
        /*
         * Define a one-column list.
         */
        listDefProc = NewListDefProc(TwistDownLDEF);
        stubHandle = (StubHandle) GetResource('LDEF', LDEF_Stub);
        if (stubHandle == NULL)
            goto exit;                    /* Failure                                */
        (**stubHandle).ldefAddress = listDefProc;
        HNoPurge((Handle) stubHandle);
        SetRect(&dataBounds, 0, 0, 1, 0);
        theList = LNew(
                &listRect,                /* Viewing area                            */
                &dataBounds,            /* Rows and col's                        */
                cellSize,                /* Element size                            */
                LDEF_Stub,                /* Callback defproc                        */
                currentPort,            /* Display window                        */
                TRUE,                    /* Draw it                                */
                hasGrowBox,                /* Grow box if TRUE                        */
                TRUE,                    /* Horizontal scroll                    */
                TRUE                    /* Vertical scroll                        */
            );
        if (theList == NULL)
            goto exit;
        LIST.selFlags = SELECTION_FLAGS;
        LIST.refCon = 0;                /* Paranoia                                */
        LIST.userHandle = NewHandleClear(sizeof (TwistDownPrivateRecord));
        if (LIST.userHandle == NULL)
            goto failure;
        privatePtr = (TwistDownPrivatePtr) (*LIST.userHandle);
#define PRIV (*privatePtr)
        PRIV.drawProc = (drawProc != NULL) ? drawProc : DefaultTwistDownDrawProc;
        PRIV.tabIndent = tabIndent;
        PRIV.canHiliteSelection = canHiliteSelection;
        PRIV.isLeftJustify = isLeftJustify;
        PRIV.fontNumber = currentPort->txFont;
        PRIV.fontSize = currentPort->txSize;
        /*
         * Grab the horizontal scrollbar and clear it from the list record then
         * link the horizontal scrollbar back to the list, and configure it.
         */
        PRIV.hScroll = LIST.hScroll;
        LIST.hScroll = NULL;
        SetControlReference(PRIV.hScroll, (long) theList);
        AdjustHorizontalScrollbar(theList);
#undef PRIV
        CreateTwistDownButtons(theList);
        goto exit;
failure:
        DisposeTwistDownList(theList);
        theList = NULL;
exit:    return (theList);
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * DisposeTwistDownList
 *
 * Dispose of the list and our private data.
 */
pascal void
DisposeTwistDownList(
        ListHandle                theList
    )
{
        if (theList != NULL) {
            if (LIST.userHandle != NULL) {
                LIST.hScroll = PRIVATE.hScroll;
                ForgetPoly(PRIVATE.openTriangle);
                ForgetPoly(PRIVATE.closedTriangle);
                ForgetPoly(PRIVATE.intermediateTriangle);
                DisposeHandle((Handle) LIST.userHandle);
                LIST.userHandle = NULL;
            }
            LDispose(theList);
        }
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * SetTwistDownListFont
 *
 * Change the display font and font size
 */
pascal void
SetTwistDownListFont(
        ListHandle                theList,
        short                    fontNumber,
        short                    fontSize
    )
{
        FontInfo                info;
        Rect                    listRect;
        Point                    cellSize;

        PRIVATE.fontNumber = fontNumber;
        PRIVATE.fontSize = fontSize;
        SetPort(LIST.port);
        TextFont(PRIVATE.fontNumber);
        TextSize(PRIVATE.fontSize);
        GetFontInfo(&info);
        listRect = LIST.rView;
        cellSize.h = width(listRect);
        cellSize.v = info.ascent + info.descent + info.leading;
        LIST.indent.v = info.ascent;
        LCellSize(cellSize, theList);
        CreateTwistDownButtons(theList);
        InvalRect(&listRect);
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * UpdateTwistDownList
 * Explicitly update the twistdown list. This is generally called only after
 * a Modal Dialog or Alert obscured the window.
 */
pascal void
UpdateTwistDownList(
        ListHandle                theList
    )
{
        WindowPtr                theWindow;
        GrafPtr                    savePort;
        Rect                    viewRect;
        RgnHandle                listRgn;
        RgnHandle                clipRgn;

        if (theList != NULL) {
            theWindow = (WindowPtr) LIST.port;
            if (EmptyRgn(((WindowPeek) theWindow)->updateRgn) == FALSE) {
                viewRect = LIST.rView;
                if (LIST.hScroll != NULL || PRIVATE.hScroll != NULL)
                    viewRect.bottom += kScrollBarWidth;
                if (LIST.vScroll != NULL)
                    viewRect.right += kScrollBarWidth;
                listRgn = NewRgn();
                RectRgn(listRgn, &viewRect);
                SectRgn(listRgn, ((WindowPeek) theWindow)->updateRgn, listRgn);
                if (EmptyRgn(listRgn) == FALSE) {
                    /*
                     * Fake an update event handler
                     */
                    GetPort(&savePort);
                    SetPort(theWindow);
                    clipRgn = NewRgn();
                    GetClip(clipRgn);
                    SetClip(listRgn);
                    EraseRgn(listRgn);
                    DrawControls(theWindow);
                    DrawGrowIcon(theWindow);
                    InsetRect(&viewRect, -1, -1);
                    FrameRect(&viewRect);
                    LUpdate(listRgn, theList);
                    DisposeRgn(clipRgn);
                    ValidRgn(listRgn);
                    SetPort(savePort);
                }
                DisposeRgn(listRgn);
            }
        }
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * MoveTwistDownList
 * Move the list within the window.
 */
pascal void
MoveTwistDownList(
        ListHandle                theList,
        short                    leftEdge,
        short                    topEdge
    )
{
        Rect                    viewRect;

        if (LIST.rView.left != leftEdge || LIST.rView.top != topEdge) {
            viewRect = LIST.rView;
            InsetRect(&viewRect, -1, -1);
            InvalRect(&viewRect);
            OffsetRect(
                &LIST.rView,
                leftEdge - LIST.rView.left,
                topEdge - LIST.rView.top
            );
            viewRect = LIST.rView;
            InsetRect(&viewRect, -1, -1);
            InvalRect(&viewRect);
            MoveControl(
                LIST.vScroll,
                LIST.rView.right - kScrollBarOffset,
                LIST.rView.top - 1
            );
            MoveControl(
                PRIVATE.hScroll,
                LIST.rView.left - 1,
                LIST.rView.bottom - kScrollBarOffset
            );
        }
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * SizeTwistDownList
 * Resize the list. The viewRect is the list rectangle size and does not include
 * the scrollbars. To create a full-screen list, pass the window's portRect with
 * the scrollbars removed.
 */
pascal void
SizeTwistDownList(
        ListHandle                theList,
        short                    newWidth,
        short                    newHeight
    )
{
        Rect                    viewRect;
        Point                    cellSize;
        GrafPtr                    currentPort;
        GrafPtr                    listPort;

        GetPort(¤tPort);
        listPort = LIST.port;
        SetPort(listPort);
        viewRect = LIST.rView;
        InsetRect(&viewRect, -1, -1);
        InvalRect(&viewRect);
        /*
         * Put the horizontal scrollbar back into the list record so that
         * the list manager does the resizing for us.
         */
        LIST.hScroll = PRIVATE.hScroll;
        LSize(newWidth, newHeight, theList);
        LIST.hScroll = NULL;
        cellSize = LIST.cellSize;
        cellSize.h = width(LIST.rView);
        LCellSize(cellSize, theList);
        AdjustHorizontalScrollbar(theList);
        viewRect = LIST.rView;
        InsetRect(&viewRect, -1, -1);
        InvalRect(&viewRect);
        SetPort(currentPort);
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * CreateTwistDownButtons
 *
 * CreateTwistDownButtons
 * This function creates the three states of the twist-down button that are drawn
 * in the display list.
 *
 * CreateTwistDownButtons is called when the list is created. The application must
 * call it directly after changing the list cell height (by calling LSize).
 *
 * Note that the port and text drawing characteristics must have been set.
 */
pascal void
CreateTwistDownButtons(
        ListHandle                theList
    )
{
        short                    buttonSize;
        short                    halfSize;
        short                    intermediateSize;
        FontInfo                info;

        ForgetPoly(PRIVATE.openTriangle);
        ForgetPoly(PRIVATE.closedTriangle);
        ForgetPoly(PRIVATE.intermediateTriangle);
        GetFontInfo(&info);
        buttonSize = info.ascent;                /* The "show sublist" button    */
        buttonSize &= ~1;                        /* Round down to an even number    */
        halfSize = buttonSize / 2;
        intermediateSize = (buttonSize * 3) / 4;
        PRIVATE.openTriangle = OpenPoly();
            MoveTo(0, halfSize);
            LineTo(buttonSize, halfSize);
            LineTo(halfSize, buttonSize);
            LineTo(0, halfSize);
        ClosePoly();
        if (PRIVATE.isLeftJustify) {            /* Roman alphabet triangles        */
            PRIVATE.closedTriangle = OpenPoly();
                MoveTo(halfSize, 0);
                LineTo(buttonSize, halfSize);
                LineTo(halfSize, buttonSize);
                LineTo(halfSize, 0);
            ClosePoly();
            PRIVATE.intermediateTriangle = OpenPoly();
                MoveTo(intermediateSize, 0);
                LineTo(intermediateSize, intermediateSize);
                LineTo(0, intermediateSize);
                LineTo(intermediateSize, 0);
            ClosePoly();
        }
        else {                                    /* Arabic/Hebrew triangles        */
            PRIVATE.closedTriangle = OpenPoly();
                MoveTo(buttonSize - halfSize, 0);
                LineTo(0, halfSize);
                LineTo(buttonSize - halfSize, buttonSize);
                LineTo(buttonSize - halfSize, 0);
            ClosePoly();
            PRIVATE.intermediateTriangle = OpenPoly();
                MoveTo(buttonSize - intermediateSize, 0);
                LineTo(buttonSize - intermediateSize, intermediateSize);
                LineTo(buttonSize, intermediateSize);
                LineTo(buttonSize - intermediateSize, 0);
            ClosePoly();
        }
        /*
         * Remember the width of the "button" area.
         */
        PRIVATE.triangleWidth =
                    (**PRIVATE.openTriangle).polyBBox.right
                    + kTriangleOutsideGap
                    + kTriangleInsideGap;
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * DoTwistDownClick
 *
 * DoTwistDownClick handles all processing after a click in the list window.
 * It returns an indication of the user action:
 *    kTwistDownNotInList
 *        The click was not in this list. Your application may ignore this click or
 *        take other appropriate action.
 *    kTwistDownNoClick
 *        The user released the mouse outside of the list area: this click should be
 *        ignored. (It may have been a click in the scroll bar.)
 *    kTwistDownButtonClick
 *        The user clicked on the twist-down button. The list will be expanded or
 *        contracted as appropriate.
 *    kTwistDownClick
 *        The user clicked (once) on a list datum. The application should treat this
 *        as an item selection.
 *    kTwistDownDoubleClick
 *        The user double-clicked on a list datum. The application should open this
 *        item or take other appropriate action.
 *
 * If DoTwistDownClick returns kTwistDownButtonClick, kTwistDownClick, or
 * kTwistDownDoubleClick, selectedListCell will be set to the cell that the user
 * clicked on.
 */
pascal TwistDownClickState
DoTwistDownClick(
        ListHandle                theList,
        const EventRecord        *eventRecordPtr,
        Cell                    *selectedListCell
    )
{
        Cell                    theCell;
        Rect                    hitRect;
        Boolean                    inHitRect;
        Boolean                    newInHitRect;
        short                    cellHeight;
        short                    visibleTop;
        TwistDownHdl            twistDownHandle;
        Point                    mousePt;
        TwistDownClickState        result;
        long                    finalTicks;
        short                    part;
        ControlHandle            theControl;
        static ControlActionUPP    controlActionUPP;

        mousePt = eventRecordPtr->where;
        GlobalToLocal(&mousePt);
        /*
         * We handle the horizontal scrollbar ourselves -- and do not pass
         * these clicks to LClick as the scrollbar isn't there anymore.
         */
        hitRect = (**PRIVATE.hScroll).contrlRect;
        if (PtInRect(mousePt, &hitRect)) {
            part = FindControl(
                        mousePt,
                        (**PRIVATE.hScroll).contrlOwner,
                        &theControl
                    );
            if (part >= 0 && theControl == PRIVATE.hScroll) {
                if (part == kInIndicatorControlPart) {
                    if (TrackControl(theControl, mousePt, NULL))
                        ScrollTwistDownList(theControl);
                }
                else {
                    if (controlActionUPP == NULL) {
                        controlActionUPP = NewControlActionProc(
                                    ScrollTwistDownActionProc
                                );
                    }
                    TrackControl(theControl, mousePt, controlActionUPP);
                }
            }
        }
        else {
            hitRect = LIST.rView;
            hitRect.right += kScrollBarWidth;
            if (PtInRect(mousePt, &hitRect) == FALSE)
                result = kTwistDownNotInList;
            else {
                /*
                 * Set hitRect to the area of the list that contains the
                 * twist-down triangle button. Note that this presumes a list
                 * where only column zero is displayed.
                 */
                if (PRIVATE.isLeftJustify) {
                    hitRect.right = LIST.rView.left
                            + LIST.indent.h
                            + PRIVATE.triangleWidth;
                }
                else {
                    hitRect.left = LIST.rView.right
                            - LIST.indent.h
                            - PRIVATE.triangleWidth;
                }
                inHitRect = FALSE;
                if (PtInRect(mousePt, &hitRect)) {
                    /*
                     * It's in a the triangle area. Find the selected cell and
                     * check whether this cell's element has a visible button.
                     */
                    visibleTop = LIST.visible.top;
                    cellHeight = LIST.cellSize.v;
                    theCell.h = 0;        /* This has the visual content            */
                    theCell.v =
                        ((mousePt.v - LIST.rView.top) / cellHeight)
                        + visibleTop;
                    /*
                     * Set inHitRect TRUE if there is a sub-list button here.\
                     * Note: it is possible to have a button but no actual
                     * sub-list (consider an empty folder in a disk hierarchy: the
                     * presence of the button tells the user "it's a folder").
                     */
                    twistDownHandle = GetTwistDownElementHandle(theList, theCell);
                    if (twistDownHandle != NULL
                     && TestTDFlag(twistDownHandle, kHasTwistDown))
                        inHitRect = TRUE;
                }
                if (inHitRect == FALSE) {
                    /*
                     * This cell doesn't have an expansion triangle, or the user
                     * did not click in the button area. Just call the  normal
                     * list click handler to manage the scroll bars. Set result
                     * appropriately.
                     */
                    result = (LClick(mousePt, eventRecordPtr->modifiers, theList))
                        ? kTwistDownDoubleClick
                        : kTwistDownClick;
                }
                else {
                    /*
                     * The user clicked on in the twist-down button area. Simulate
                     * a button click and track the mouse as it wanders in and out
                     * of the button area. (inHitRect is true at this point).
                     * Whenever the button selection state changes, call LDraw to
                     * redraw the twist-down triangle. This is the way to simulate
                     * TrackControl.
                     */
                    SetTDFlag(twistDownHandle,
                        (kDrawButtonFilled | kOnlyRedrawButton));
                    LDraw(theCell, theList);
                    /*
                     * Set hitRect to the dimensions of the twist-down button.
                     */
                    hitRect.top =
                        ((theCell.v - visibleTop) * cellHeight)
                        + LIST.rView.top;
                    hitRect.bottom = hitRect.top + cellHeight;
                    /*
                     * Track the mouse while it still down: if it moves into the
                     * triangle rectangle, redraw it filled, if it moves out of
                     * the triangle, redraw it unfilled.
                     */
                    if (StillDown()) {
                        while (WaitMouseUp()) {
                            GetMouse(&mousePt);
                            newInHitRect = PtInRect(mousePt, &hitRect);
                            if (newInHitRect != inHitRect) {
                                /*
                                 * The mouse moved in or out of the triangle.
                                 */
                                InvertTDFlag(twistDownHandle, kDrawButtonFilled);
                                LDraw(theCell, theList);
                                inHitRect = newInHitRect;
                            }
                        }
                    }
                    /*
                     * The user released the mouse.
                     */
                    if (inHitRect == FALSE) {
                        /*
                         * Normally, drawButtonFilled will be clear. It can be set,
                         * however, if the user clicks so briefly on the triangle
                         * that the StillDown() test above is FALSE.
                         */
                        if (TestTDFlag(twistDownHandle, kDrawButtonFilled)) {
                            ClearTDFlag(twistDownHandle, kDrawButtonFilled);
                            LDraw(theCell, theList);
                        }
                        result = kTwistDownNoClick;
                    }
                    else {
                        /*
                         * The user released the mouse in the expansion triangle.
                         * Draw an intermediate "animation" triangle. Then call
                         * ExpandOrCollapseTwistDownList which will redraw the
                         * button in its new state.
                         */
                        SetTDFlag(twistDownHandle,
                            (kDrawIntermediate | kEraseButtonArea));
                        LDraw(theCell, theList);
                        Delay(kAnimationDelay, &finalTicks);
                        ClearTDFlag(
                            twistDownHandle,
                            (  kDrawIntermediate
                             | kDrawButtonFilled
                             | kEraseButtonArea
                            )
                        );
                        ExpandOrCollapseTwistDownList(theList, theCell);
                        result = kTwistDownButtonClick;
                        *selectedListCell = theCell;
                    }
                    ClearTDFlag(twistDownHandle, kOnlyRedrawButton);
                }
            }
        }
        return (result);
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * ExpandOrCollapseTwistDownList
 *
 * ExpandOrCollapseTwistDownList modifies the "show sublist" flag for the selected
 * cell and rebuilds the visual display.
 */
pascal void
ExpandOrCollapseTwistDownList(
        ListHandle                theList,
        Cell                    selectedListCell
    )
{
        TwistDownHdl            twistDownHandle;

        twistDownHandle = GetTwistDownElementHandle(theList, selectedListCell);
        if (twistDownHandle != NULL
         && TestTDFlag(twistDownHandle, kHasTwistDown)) {
            InvertTDFlag(twistDownHandle, kShowSublist);
            /*
             * Redraw the twist-down button in its new state.
             */
            ClearTDFlag(twistDownHandle, kDrawButtonFilled);
            SetTDFlag(twistDownHandle, (kOnlyRedrawButton | kEraseButtonArea));
            LDraw(selectedListCell, theList);
            ClearTDFlag(twistDownHandle, (kOnlyRedrawButton | kEraseButtonArea));
            /*
             * If some other part of the list will change, rebuild the
             * List Manager list cells and redraw the list.
             */
            if ((**twistDownHandle).subElement != NULL)
                BuildVisibleList(theList, selectedListCell.v);
        }
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * CreateVisibleList
 *
 * CreateVisibleList is called when the list is created. It stores the list
 * head into cell [0, 0] and calls BuildVisibleList to instantiate the display.
 */
pascal void
CreateVisibleList(
        ListHandle                theList,
        TwistDownHdl            twistDownHandle
    )
{
        Cell                    theCell;

        if (LIST.dataBounds.bottom == 0) {
            /*
             * Add one row to the list so there is a place for the head element.
             */
            LSetDrawingMode(FALSE, theList);
            LAddRow(1, 0, theList);
            LSetDrawingMode(TRUE, theList);
        }
        SetPt(&theCell, 0, 0);
        LSetCell(&twistDownHandle, sizeof twistDownHandle, theCell, theList);
        BuildVisibleList(theList, 0);
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * BuildVisibleList
 *
 * BuildVisibleList is called when the list is created, or when the user clicks
 * on a twist-down button. selectedRow is the first row that needs to be redrawn.
 * To rebuild the entire list, store the list head into cell [0, 0] and call
 * with selectedRow = 0. Note: because people can be rebuilding the list from
 * within a larger sublist context, the list head must be stored in cell [0, 0].
 */
pascal void
BuildVisibleList(
        ListHandle                theList,
        short                    selectedRow
    )
{
        short                    nRows;            /* How many we need    to show        */
        short                    currentRows;    /* How many are in the list        */
        Rect                    viewRect;
        TwistDownHdl            listHead;
        Cell                    theCell;

        LSetDrawingMode(FALSE, theList);
        SetPt(&theCell, 0, 0);                        /* Get the list head        */
        listHead = GetTwistDownElementHandle(theList, theCell);
        ClearSelectedElementBit(listHead);
        CopySelectionStateToList(theList, selectedRow);
        nRows = CountVisibleElements(listHead);
        currentRows = LIST.dataBounds.bottom;
        if (currentRows > nRows)
            LDelRow(currentRows - nRows, nRows, theList);    /* Shrink the list    */
        else if (currentRows < nRows)
            LAddRow(nRows - currentRows, currentRows + 1, theList);    /* Grow it    */
        if (nRows != 0)
            SetElementsInList(theList, listHead, &theCell);
        LSetDrawingMode(TRUE, theList);
        /*
         * Redraw any elements that are greater than the inserted row.
         */
        viewRect = LIST.rView;
        viewRect.top += ((selectedRow + 1) - LIST.visible.top)
                    * LIST.cellSize.v;
        if (viewRect.top < viewRect.bottom)
            InvalRect(&viewRect);
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * CountVisibleElements
 *
 * CountVisibleElements is a recursive function that returns the number of visible
 * elements in the list. Call with the list head to process the entire list. Note:
 * list elements are visible, but sub-lists are visible only if the button state
 * requests visiblity. This function may be called with a NULL argument without
 * problems. Also note that we ignore the current List Manager cell data, working
 * only with the actual linked list structure. By convention, however, the list
 * head is stored in cell [0, 0].
 */
static short
CountVisibleElements(
        TwistDownHdl            twistDownHandle
    )
{
        short                    result;

        result = 0;
        while (twistDownHandle != NULL) {
            ++result;
            if (TestTDFlag(twistDownHandle, kShowSublist))
                result += CountVisibleElements((**twistDownHandle).subElement);
            twistDownHandle = (**twistDownHandle).nextElement;
        }
        return (result);
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * CountListElements
 *
 * CountListElements returns the number of elements in the list: it counts all
 * elements in all sub-lists, visible or not.
 */
pascal unsigned long
CountListElements(
        TwistDownHdl            twistDownHandle
    )
{
        unsigned long            result;

        result = 0;
        while (twistDownHandle != NULL) {
            ++result;
            if ((**twistDownHandle).subElement != NULL)
                result += CountVisibleElements((**twistDownHandle).subElement);
            twistDownHandle = (**twistDownHandle).nextElement;
        }
        return (result);
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * ClearSelectedElementBit
 *
 * When we expand or contract the visible list, the relationship between the
 * visual display and the actual data changes. In particular, the selected cell
 * may contain different data. To resolve this dilemna, we copy the current
 * selection from the display list to the data elements, then copy the information
 * back when the new elements are inserted into the list. This is a three-step
 * process. First, we clear out the kSelectedElement bit from the linked list.
 */
static void
ClearSelectedElementBit(
        TwistDownHdl            twistDownHandle
    )
{
        while (twistDownHandle != NULL) {
            ClearTDFlag(twistDownHandle, kSelectedElement);
            if ((**twistDownHandle).subElement != NULL)
                ClearSelectedElementBit((**twistDownHandle).subElement);
            twistDownHandle = (**twistDownHandle).nextElement;
        }
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * CopySelectionStateToList
 *
 * After clearing the kSelectedElementBit from the element list, we save the
 * "is selected" bit from the display list into the associated element. Note that
 * the cell will be deselected but selection state is restored when the list is
 * rebuilt. The function starts with the row after the selected (clicked on) cell
 * as that cell is not redrawn and, presumably, is correctly hilited.
 */
static void
CopySelectionStateToList(
        ListHandle                theList,
        short                    selectedRow
    )
{
        TwistDownHdl            twistDownHandle;
        Cell                    theCell;

        SetPt(&theCell, 0, selectedRow + 1);
        while (LGetSelect(TRUE, &theCell, theList)) {
            twistDownHandle = GetTwistDownElementHandle(theList, theCell);
            if (twistDownHandle != NULL)
                SetTDFlag(twistDownHandle, kSelectedElement);
            LSetSelect(FALSE, theCell, theList);
            ++theCell.v;
        }
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * SetElementsInList
 *
 * This is a recursive function that copies visible list elements from the linked
 * list to the List Manager list. The List Manager list was extended so it holds
 * all visible cells. Note that currentCell is a "global" that always contains
 * the current List Manager cell. To process the entire list, set currentCell to
 * [0, 0] and call with the list head. If the list element is selected (from
 * CopySelectionStateToList above), select this list cell.
 */
static void
SetElementsInList(
        ListHandle                theList,
        TwistDownHdl            twistDownHandle,
        Cell                    *currentCell
    )
{
        while (twistDownHandle != NULL) {
            LSetCell(
                &twistDownHandle, sizeof twistDownHandle, *currentCell, theList);
            if (TestTDFlag(twistDownHandle, kSelectedElement))
                LSetSelect(TRUE, *currentCell, theList);
            ++currentCell->v;
            if (TestTDFlag(twistDownHandle, kShowSublist)) {
                SetElementsInList(
                    theList,
                    (**twistDownHandle).subElement,
                    currentCell
                );
            }
            twistDownHandle = (**twistDownHandle).nextElement;
        }
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * GetTwistDownElementHandle
 *
 * GetTwistDownElementHandle returns the TwistDownHdl that is stored in a List
 * cell. It will return NULL if the cell is out of bounds.
 */
pascal TwistDownHdl
GetTwistDownElementHandle(
        ListHandle                theList,
        Cell                    theCell
    )
{
        TwistDownHdl            twistDownHandle;
        short                    dataSize;

        dataSize = sizeof twistDownHandle;
        LGetCell(&twistDownHandle, &dataSize, theCell, theList);
        if (dataSize != sizeof twistDownHandle)
            twistDownHandle = NULL;
        return (twistDownHandle);
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * NewTwistDownSiblingSet
 *
 * Initialize a sibling set.
 */
pascal void
NewTwistDownSiblingSet(
        TwistDownSiblingSetPtr    twistDownSiblingSetPtr
    )
{
        SIBLING.thisElement = NULL;
        SIBLING.firstElement = NULL;
        SIBLING.previousElement = NULL;
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * MakeTwistDownSibling
 *
 * Add a new element (by calling MakeTwistDownElement) to the end of the current
 * linked list. Also, handle the bookkeeping needed for the first element.
 */
pascal OSErr
MakeTwistDownSibling(
        TwistDownSiblingSetPtr    twistDownSiblingSetPtr,
        short                    indentLevel,
        unsigned short            dataLength,
        const Ptr                dataPtr
    )
{
        OSErr                    status;

        status = MakeTwistDownElement(
                    SIBLING.previousElement,
                    indentLevel,
                    dataLength,
                    dataPtr,
                    &SIBLING.thisElement
                );
        if (status == noErr) {
            SIBLING.previousElement = SIBLING.thisElement;
            if (SIBLING.firstElement == NULL)
                SIBLING.firstElement = SIBLING.thisElement;
        }
        return (status);
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * MakeTwistDownElement
 *
 * Adds an element to a linked list. It is designed to create elements in a
 * hierarchical linked-list where each element may be followed by a successor
 * (on the same "level") and/or by a child list (on a lower "level"). Note that
 * MakeTwistDownElement is only concerned with the linked list. It does not
 * change the List Manager list.
 *
 * The parameters are as follows:
 *    previousElement
 *        This is a handle to the predecessor to this element. previousElement is
 *        NULL If this is the first element in a list or the first on a level.
 *    indentLevel
 *        This is the indentation-level of this list element. It is only
 *        used to tab the list elements on the visual display. If you don't
 *        want tabbing, set tabIndent to zero when the list was created.
 *    dataLength
 *        This is the length of the list element datum.
 *    dataPtr
 *        This is a pointer to the first byte of the list element datum. If NULL,
 *        a data block of the requisite size will be created, but the caller is
 *        responsible for filling it in.
 *    result
 *        If MakeElement succeeds, result will will contain a handle to the
 *        list element it created. This is needed to create a successor
 *        element.
 */
pascal OSErr
MakeTwistDownElement(
        TwistDownHdl            previousElement,
        short                    indentLevel,
        unsigned short            dataLength,
        const Ptr                dataPtr,
        TwistDownHdl            *result
    )
{
        TwistDownHdl            twistDownHandle;

        twistDownHandle = (TwistDownHdl) NewHandle(
                    sizeof (TwistDownRecord)
                    - sizeof (unsigned char)
                    + dataLength
                );
        if (twistDownHandle != NULL) {
            if (previousElement != NULL)
                (**previousElement).nextElement = twistDownHandle;
            (**twistDownHandle).nextElement = NULL;
            (**twistDownHandle).subElement = NULL;
            (**twistDownHandle).flag = 0;
            (**twistDownHandle).indentLevel = indentLevel;
            (**twistDownHandle).dataLength    = dataLength;
            if (dataPtr != NULL)
                BlockMoveData(dataPtr, (**twistDownHandle).data, dataLength);
            *result = twistDownHandle;
        }
        return (MemError());
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * DisposeTwistDownHdl
 *
 * Dispose of the linked list that has the argument at its head, and of all
 * sublists linked to this list. Note that it presumes that the list element does
 * not, itself, contain Ptr or Handle data that must be disposed. The userProc,
 * if provided, will be called on each element.
 */
pascal void
DisposeTwistDownHdl(
        TwistDownHdl            twistDownHandle,
        DisposeTwistDownCallback userProc,
        void                    *userData
    )
{
        TwistDownHdl            nextElement;
        TwistDownHdl            subElement;

        while (twistDownHandle != NULL) {
            nextElement = (**twistDownHandle).nextElement;
            subElement = (**twistDownHandle).subElement;
            if (userProc != NULL)
                (*userProc)(twistDownHandle, userData);
            DisposeHandle((Handle) twistDownHandle);
            if (subElement != NULL)
                DisposeTwistDownHdl(subElement, userProc, userData);
            twistDownHandle = nextElement;
        }
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * AppendTwistDownList
 *
 * Append the second list to the first list. Return the first list.
 */
pascal TwistDownHdl
AppendTwistDownList(
        TwistDownHdl            dstTwistDownHdl,
        TwistDownHdl            srcTwistDownHdl
    )
{
        TwistDownHdl            result;

        if ((result = dstTwistDownHdl) == NULL)
            result = srcTwistDownHdl;
        else {
            while ((**dstTwistDownHdl).nextElement != NULL)
                dstTwistDownHdl = (**dstTwistDownHdl).nextElement;
            (**dstTwistDownHdl).nextElement = srcTwistDownHdl;
        }
        return (result);
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * TwistDownLDEF
 *
 * Draw the twist-down list cell. Note that we have to draw the expansion button
 * in one of five states: (expanded/compressed), (normal/selected), and an
 * animation state.
 */
pascal void
TwistDownLDEF(
        short                    listMessage,
        Boolean                    listSelect,
        Rect                    *listRect,
        Cell                    listCell,
        short                    listDataOffset,
        short                    listDataLen,
        ListHandle                theList
    )
{
        short                    indent;
        TwistDownHdl            twistDownHandle;
        register TwistDownPtr    twistDownPtr;
        GrafPtr                    grafPtr;
        short                    saveFontNumber;
        short                    saveFontSize;
        short                    cellSize;
        PolyHandle                polyHandle;
        Point                    polyPoint;
        Rect                    viewRect;
        signed char                elementLockState;
        Boolean                    onlyRedrawButton;
        FontInfo                info;
#define TestFlag(flagBit)    (((*twistDownPtr).flag & (flagBit)) != 0)

        UNUSED(listDataOffset);
        switch (listMessage) {
        case lInitMsg:
            /*
             * Initialize the list indentation values. Since the userHandle
             * (which has the TwistDown private data) hasn't been setup yet,
             * we let the current font and font size establish the indentation.
             */
            LIST.indent.h = 4;
            GetFontInfo(&info);
            LIST.indent.v = info.ascent;
            break;
        case lCloseMsg:
            if (LIST.userHandle != NULL) {
                ForgetPoly(PRIVATE.openTriangle);
                ForgetPoly(PRIVATE.closedTriangle);
                ForgetPoly(PRIVATE.intermediateTriangle);
                DisposeHandle(LIST.userHandle);
                LIST.userHandle = NULL;
            }
            break;
        case lDrawMsg:
            onlyRedrawButton = FALSE;
            if (listDataLen > 0 && LIST.userHandle != NULL) {
                /*
                 * Get the cell content. This is the handle that has the list
                 * element. We check that the userHandle has been setup correctly.
                 * Note that we don't use LFind (or similar) because the data
                 * might not be aligned in the list cell storage. Actually, the
                 * data is aligned as we only store Handles in the cells.
                 */
                cellSize = sizeof twistDownHandle;
                LGetCell(&twistDownHandle,    &cellSize, listCell, theList);
                if (cellSize == sizeof twistDownHandle
                 && twistDownHandle != NULL) {
                    elementLockState = HGetState((Handle) twistDownHandle);
                    HLock((Handle) twistDownHandle);
                    twistDownPtr = (*twistDownHandle);
                    onlyRedrawButton = TestFlag(kOnlyRedrawButton);
                    viewRect = *listRect;
                    if (onlyRedrawButton) {
                        if (PRIVATE.isLeftJustify) {
                            viewRect.right = viewRect.left
                                        + LIST.indent.h
                                        + PRIVATE.triangleWidth;
                        }
                        else {
                            viewRect.left = viewRect.right
                                    - LIST.indent.h
                                    - kTriangleOutsideGap
                                    - PRIVATE.triangleWidth;
                        }
                    }
                    if (onlyRedrawButton == FALSE || TestFlag(kEraseButtonArea))
                        EraseRect(&viewRect);
                    if (TestFlag(kHasTwistDown)) {
                        /*
                         * Draw the expansion triangle in one of
                         * its three states.
                         */
                        polyPoint.v = listRect->top + 1;
                        if (PRIVATE.isLeftJustify) {
                            polyPoint.h = listRect->left
                                        + LIST.indent.h
                                        + kTriangleOutsideGap;
                        }
                        else {
                            polyPoint.h = listRect->right
                                        - LIST.indent.h
                                        - PRIVATE.triangleWidth
                                        + kTriangleInsideGap;
                        }
                        if (TestFlag(kDrawIntermediate))
                            polyHandle = PRIVATE.intermediateTriangle;
                        else if (TestFlag(kShowSublist))
                            polyHandle = PRIVATE.openTriangle;
                        else {
                            polyHandle = PRIVATE.closedTriangle;
                        }
                        DrawTriangle(
                            polyHandle,
                            polyPoint,
                            TestFlag(kDrawButtonFilled)
                        );
                    }
                    if (onlyRedrawButton == FALSE
                     && (*twistDownPtr).dataLength > 0) {
                        /*
                         * Indent the text to show the depth of the hierarchy.
                         */
                        indent = LIST.indent.h
                            + PRIVATE.triangleWidth
                            + (PRIVATE.tabIndent * (*twistDownPtr).indentLevel);
                        viewRect = *listRect;
                        /*
                         * Build a display rectangle for the cell text and set the
                         * pen to the leftmost position of the text. Note that
                         * this right-justifies text for Arabic and Hebrew.
                         */
                        if (PRIVATE.isLeftJustify)
                            viewRect.left += indent;
                        else {
                            viewRect.right -= indent;
                        }
                        GetPort(&grafPtr);
                        saveFontNumber = grafPtr->txFont;
                        saveFontSize = grafPtr->txSize;
                        TextFont(PRIVATE.fontNumber);
                        TextSize(PRIVATE.fontSize);
                        (PRIVATE.drawProc)(theList, twistDownPtr, &viewRect);
                        TextFont(saveFontNumber);
                        TextSize(saveFontSize);
                    }                            /* Drawing cell                    */
                    HSetState((Handle) twistDownHandle, elementLockState);
                }                                /* Have list element            */
            }                                    /* Have cell data                */
            if (listSelect == FALSE || onlyRedrawButton)
                break;
            /* Continue to do hilite */
        case lHiliteMsg:
            if (PRIVATE.canHiliteSelection) {
                LMSetHiliteMode(LMGetHiliteMode() & ~(1 << hiliteBit));
                viewRect = *listRect;
                if (PRIVATE.isLeftJustify)
                    viewRect.left += (LIST.indent.h * PRIVATE.triangleWidth);
                else {
                    viewRect.right -= (LIST.indent.h * PRIVATE.triangleWidth);
                }
                InvertRect(&viewRect);
            }
            break;
        }
#undef TestFlag
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * DrawTriangle
 *
 * Draw the polygon and fill it so it looks a bit like the Finder. If isSelected
 * is TRUE, the polygon is always black-filled. Else, on color monitors, a light
 * gray is chosen.
 *
 * DrawTriangle uses the DeviceLoop available with System 7 to draw across
 * multiple screens.
 */

typedef struct TriangleInfo {
    PolyHandle        polyHandle;
    Point            polyPoint;
} TriangleInfo, *TriangleInfoPtr;

static pascal void            DrawThisTriangle(
        short                    depth,
        short                    deviceFlags,
        GDHandle                targetDevice,
        TriangleInfoPtr            triangleInfoPtr
    );

static void
DrawTriangle(
        PolyHandle                polyHandle,
        Point                    polyPoint,
        Boolean                    isSelected
    )
{
        TriangleInfo            triangleInfo;
        RgnHandle                drawingRgn;
        long                    savedA5;
        static DeviceLoopDrawingUPP drawingProcUPP;
        /*
         * Refresh A5 so we can use the QuickDraw globals, even if we're called
         * in a non-application context.
         */
        savedA5 = SetCurrentA5();
        triangleInfo.polyHandle = polyHandle;
        triangleInfo.polyPoint = polyPoint;
        OffsetPoly(polyHandle, polyPoint.h, polyPoint.v);
        if (isSelected)
            FillPoly(polyHandle, &qd.black);
        else {
            drawingRgn = NewRgn();
            OpenRgn();
            FramePoly(polyHandle);
            CloseRgn(drawingRgn);
            if (drawingProcUPP == NULL)
                drawingProcUPP = NewDeviceLoopDrawingProc(DrawThisTriangle);
            DeviceLoop(drawingRgn, drawingProcUPP, (long) &triangleInfo, 0);
            DisposeRgn(drawingRgn);
        }
        /*
         * A thicker pen might look better for large font sizes, but it needs
         * to be done in a way that looks good for both button orientations.
         */
        FramePoly(polyHandle);
        OffsetPoly(polyHandle, -polyPoint.h, -polyPoint.v);
        SetA5(savedA5);
}

static pascal void
DrawThisTriangle(
        short                    depth,
        short                    deviceFlags,
        GDHandle                targetDevice,
        TriangleInfoPtr            triangleInfoPtr
    )
{
        RGBColor                foreColor;
        RGBColor                saveForeColor;
        RGBColor                backColor;
        short                    i;
        Rect                    polyRect;
#define TRI    (*triangleInfoPtr)

        UNUSED(deviceFlags);
        UNUSED(targetDevice);
        polyRect = (**TRI.polyHandle).polyBBox;
        LocalToGlobal(& ((Point *) &polyRect)[0]);
        LocalToGlobal(& ((Point *) &polyRect)[1]);
        if (depth > 1) {
            /*
             * We are drawing on a color device (or devices). Fill the unselected
             * triangle with a very light gray. The Finder extends this by filling
             * using the icon color instead of black.
             */
            GetForeColor(&foreColor);
            saveForeColor = foreColor;
            GetBackColor(&backColor);
            /*
             * This loop sets foreColor to a very light gray.
             */
            for (i = 0; i < 8; i++) {
                if (GetGray(GetGDevice(), &backColor, &foreColor) == FALSE)
                    break;
            }
            RGBForeColor(&foreColor);
            FillPoly(TRI.polyHandle, &qd.black);
            RGBForeColor(&saveForeColor);
        }
        else {
#if MONOCHROME_FILL
            /*
             * We really don't need to do this, but it was useful in debugging
             * the algorithm on a machine with multiple displays. This fills
             * the polygon with a light gray texture on monochrome displays.
             * This is different from the Finder algorithm.
             */
            FillPoly(TRI.polyHandle, (ConstPatternParam) &qd.ltGray);
#else
            /*
             * Normally, we need only erase the interior of the polygon.
             */
            ErasePoly(TRI.polyHandle);
#endif
#undef TRI
        }
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * SortTwistDownList
 *
 * Sort a list according to the comparison function. Algorithm adapted from
 * Numerical Recipes in C (Press, Flannery, Teukolsky, & Vetterling),
 * ISBN 0-521-35465-X. Algorithm 8.2 "Heapsort"
 *
 * This is *not* a recursive procedure. It allocates a temporary array that holds
 * a oopy of the list. The algorithm, then, is:
 *    1. Count the number of elements in the list - don't count sublists, though.
 *    2. Allocate a vector to hold the list handles and copy the list handles
 *        into the vector.
 *    3. Heapsort.
 *    4. The "Promotion" phase creates a new list set.
 * The function returns noErr on success, or a memory allocation error. By using
 * a non-recursive function, we avoid a problem where an ordered input list chews
 * up the application stack, which could lead to bizarre crashes.
 */
pascal OSErr
SortTwistDownList(
        TwistDownHdl            *twistDownHdlPtr,
        TwistDownSortCompareProc sortCompareProc,
        void                    *refCon
    )
{
        OSErr                    status;
        unsigned long            nElements;
        unsigned long            i;
        unsigned long            j;
        unsigned long            siftIndex;
        unsigned long            lastIndex;
        TwistDownHdl            twistDownHdl;
        TwistDownHdl            *heapVector;    /* One-origin vector        */

        nElements = 0;
        status = noErr;
        for (twistDownHdl = *twistDownHdlPtr;    /* Count list elements        */
                twistDownHdl != NULL;
                twistDownHdl = (**twistDownHdl).nextElement) {
            ++nElements;
        }
        if (nElements > 1) {            /* 0 or 1 elements aren't sorted    */
            heapVector = (TwistDownHdl *)
                        NewPtr((nElements + 1) * sizeof (TwistDownHdl));
            if (heapVector == NULL)
                status = MemError();
            else {
                /*
                 * Copy the list into the vector. Note that the vector is one-
                 * origin (this prevents an infinite loop if the index is zero).
                 */
                for (i = 1, twistDownHdl = *twistDownHdlPtr;
                        twistDownHdl != NULL;
                        twistDownHdl = (**twistDownHdl).nextElement) {
                    heapVector[i++] = twistDownHdl;
                }
                siftIndex = (nElements >> 1) + 1;
                lastIndex = nElements;
                for (;;) {
                    if (siftIndex > 1)        /* Still in hiring phase?        */
                        twistDownHdl = heapVector[--siftIndex];
                    else {                    /* Else, in promotion phase?    */
                        /*
                         * Clear a space at the end of the vector, retire the
                         * top of the heap into it, if we're done with the
                         * last promotion, store the "least competent"
                         * worker, and exit.
                         */
                        twistDownHdl = heapVector[lastIndex];
                        heapVector[lastIndex] = heapVector[1];
                        if (--lastIndex <= 1) {
                            heapVector[1] = twistDownHdl;
                            break;            /* Exit the for (;;) loop        */
                        }
                    }
                    /*
                     * Whether we are in the hiring or promotion phase, we
                     * continue here to sift the current element into its
                     * proper position.
                     */
                    i = siftIndex;
                    j = siftIndex << 1;
                    while (j <= lastIndex) {
                        if (j < lastIndex
                         && (*sortCompareProc)(
                                    refCon,
                                    heapVector[j],
                                    heapVector[j + 1]
                                ) < 0) {
                            ++j;
                        }
                        if ((*sortCompareProc)(
                                    refCon, twistDownHdl, heapVector[j]
                                ) < 0) {
                            heapVector[i] = heapVector[j];
                            i = j;
                            j += i;
                        }
                        else {
                            break;
                        }
                    }
                    heapVector[i] = twistDownHdl;
                }
                /*
                 * heapVector has the sorted list. Build the result list.
                 */
                *twistDownHdlPtr = heapVector[1];
                for (i = 2; i <= nElements; i++)
                    (**(heapVector[i - 1])).nextElement = heapVector[i];
                (**(heapVector[nElements])).nextElement = NULL;
                DisposePtr((Ptr) heapVector);
            }
        }
        return (status);

}


/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * AdjustHorizontalScrollbar
 *
 * This is called when the user clicks in the horizontal scrollbar that was
 * created when the list was created. Note that we handle the scrollbar here,
 * as it is not stored within the ListManager list record.
 */
static void
AdjustHorizontalScrollbar(
        ListHandle                theList
    )
{
        short                    horizontalMax;
        ControlHandle            theControl;

        theControl = PRIVATE.hScroll;
        horizontalMax = kMaxHorizontalScroll - width((**theControl).contrlRect);
        if (horizontalMax < 0)
            horizontalMax = 0;
        SetControlMinimum(theControl, 0);
        SetControlMaximum(theControl, horizontalMax);
        HiliteControl(
            theControl,
            (horizontalMax == 0) ? kDisabledControl : kActiveControl
        );
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * ScrollTwistDownActionProc
 *
 * This is called by TrackControl when the user clicks in the horizontal
 * scrollbar that was created when the list was created. Note that we handle
 * the scrollbar here, as it is not stored within the ListManager list record.
 */
static pascal void
ScrollTwistDownActionProc(
        register ControlHandle    theControl,
        short                    partCode
    )
{
        short                    delta;

        delta = (width((**theControl).contrlRect) * 7) / 8;
        switch (partCode) {
        case kInUpButtonControlPart:    delta = -CharWidth('M');        break;
        case kInPageUpControlPart:        delta = (-delta);                break;
        case kInDownButtonControlPart:    delta = CharWidth('M');            break;
        case kInPageDownControlPart:    /* All set */                    break;
        default:                        return;            /* Mouse exited control    */
        }
        SetControlValue(theControl, GetControlValue(theControl) + delta);
        ScrollTwistDownList(theControl);
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * ScrollTwistDownList
 *
 * This is called when the user clicks in the horizontal scrollbar that was
 * created when the list was created. This is the function that modifies the
 * scrollbar.
 */
static void
ScrollTwistDownList(
        register ControlHandle    theControl
    )
{
        ListHandle                theList;
        short                    delta;
        RgnHandle                clipRgn;
        RgnHandle                updateRgn;
        Rect                    viewRect;

        theList = (ListHandle) GetControlReference(theControl);
        /*
         * LIST.indent.h is negative when the cell is scrolled left. Get its
         * current amount (as a positive value) and set delta to the amount
         * that must be scrolled. Delta will be positive to scroll right
         * (meaning that the scroll bar moved left). This probably won't
         * work for a right-to-left language.
         */
        delta = kZeroIndent - LIST.indent.h - GetControlValue(theControl);
        if (delta != 0) {
            /*
             * We must scroll the list. Get a clip rectangle so the scrolling
             * is limited to the drawing area, scroll it, and update anything
             * that came into view. Hmm, should the buttons ever scroll?
             */
            viewRect = LIST.rView;
            clipRgn = NewRgn();
            updateRgn = NewRgn();
            GetClip(clipRgn);
            ClipRect(&viewRect);
            ScrollRect(&viewRect, delta, 0, updateRgn);
            LIST.indent.h += delta;
            LUpdate(updateRgn, theList);
            SetClip(clipRgn);
            DisposeRgn(updateRgn);
            DisposeRgn(clipRgn);
        }
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * Print Manager
 *
 * The following section lets the user print a twistdown list.
 */

static pascal OSErr            DefaultTwistDownPrintSetupProc(
        ListHandle                theList,
        THPrint                    hPrint,
        void                    *clientData,
        StringPtr                dateString
    );
static pascal OSErr            DefaultTwistDownPrintImageProc(
        ListHandle                theList,
        THPrint                    hPrint,
        void                    *clientData,
        StringPtr                dateString,
        const Rect                *pageRect,
        short                    pageNumber
    );

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * PrintTwistDownList
 *
 * Mainline print handler. This calls task-specific routines to count the number
 * of pages and to image each page. The caller may provide special routines for
 * these tasks, or use the default calls (that presume text-only list elements).
 * This is modified from Rich Siegel's generic print driver.
 */
pascal OSErr
PrintTwistDownList(
        ListHandle                theList,
        THPrint                    *printHandlePtr,
        Boolean                    doStyleDialog,
        TwistDownPrintSetupProc    twistDownPrintSetupProc,
        TwistDownPrintImageProc    twistDownPrintImageProc,
        TwistDownPrintExitProc    twistDownPrintExitProc,
        void                    *clientData
    )
{
        OSErr                    status;            /* Current error                */
        THPrint                    hPrint;            /* Copy of *printHandlePtr        */
        Boolean                    printIsOpen;    /* PROpen ... PRClose            */
        Boolean                    docIsOpen;        /* PROpenDoc ... PRCloseDoc        */
        short                    nCopies;        /* Number of copies to print    */
        short                    iCopy;            /* Which copy are we printing?    */
        short                    pageNumber;        /* Which page are we printing?    */
        Rect                    pageRect;        /* Current page image rectangle    */
        short                    printDevice;    /* What kind of printer?        */
        Boolean                    draftMode;        /* Draft or spool?                */
        TPPrPort                printPort;        /* The print port                */
        TPrStatus                printStatus;    /* PrPicFile status info        */
        GrafPtr                    savePort;        /* Old GrafPort                    */
        unsigned long            now;            /* When we're called            */
        Str255                    dateString;        /* Handy date + time string        */
#ifndef bDevCItoh
#define bDevCItoh            1
#endif
#ifndef bDevLaser
#define bDevLaser            3
#endif
        enum {
            kImageWriter        = bDevCItoh,
            kLaserWriter        = bDevLaser
        };
/*
 * This macro exits the print handler on any error.
 */
#define CheckError(stat) do {                    \
        if ((status = (stat)) != noErr)            \
            goto exit;                            \
    } while (0)
#if 1 /* Debug only */
#define CHECK(stat, why) do {                                    \
        OSErr                checkStat;                            \
        extern short NonFatalError(OSErr, ConstStr255Param);    \
        if ((checkStat = (stat)) != noErr)                        \
            NonFatalError(checkStat, why);                        \
    } while (0)
#else
#define CHECK(stat, why) /* Nothing */
#endif

        GetPort(&savePort);
        status = noErr;
        printIsOpen = FALSE;
        docIsOpen = FALSE;
        if (twistDownPrintSetupProc == NULL)
            twistDownPrintSetupProc = DefaultTwistDownPrintSetupProc;
        if (twistDownPrintImageProc == NULL)
            twistDownPrintImageProc = DefaultTwistDownPrintImageProc;
        /*
         * Set the date and time
         */
        GetDateTime(&now);
        IUDateString(now, abbrevDate, dateString);
        dateString[++dateString[0]] = ' ';
        dateString[++dateString[0]] = '/';
        iCopy = ++dateString[0];
        IUTimeString(now, FALSE, &dateString[iCopy]);
        dateString[0] += (dateString[iCopy] + 1);
        dateString[iCopy] = ' ';
        /*
         * If there is no Print Handle, allocate one and fail on errors. On exit,
         * the print handler is retained so that multiple printouts retain the
         * same user selections.
         */
        PrOpen();
        status = PrError();
        CHECK(status, "\pCan't open print manager");
        CheckError(status);
        printIsOpen = TRUE;
        if (*printHandlePtr == NULL) {
            *printHandlePtr = (THPrint) NewHandle(sizeof (TPrint));
            if (*printHandlePtr == NULL) {
                status = MemError();
                CHECK(status, "\pNewHandle(sizeof (TPrint)) failed");
                goto exit;
            }
            PrintDefault(*printHandlePtr);
        }
        hPrint = (*printHandlePtr);
        /*
         * Validate the Print Handle and call the Print Style dialog if necessary.
         * If the user cancels, exit (noErr). Then call the job dialog to get the
         * number of copies (exit on cancel here, too). Note that we don't exit
         * with userCanceledErr, as this is merely informative.
         */
        if (PrValidate(hPrint) || doStyleDialog) {
            if (PrStlDialog(hPrint) == FALSE) {
                CHECK(userCanceledErr, "\pUser canceled style dialog");
                goto exit;
            }
        }
        if (PrJobDialog(hPrint) == FALSE) {
            CHECK(userCanceledErr, "\pUser canceled job dialog");
            goto exit;
        }
        /*
         * Setup is done, call the user's setup procedure and exit on errors.
         * The setup function must set the number of pages in the document and
         * return noErr to continue.
         */
        SetCursor(*GetCursor(watchCursor));
        status = (*twistDownPrintSetupProc)
                    (theList, hPrint, clientData, dateString);
        CHECK(status, "\pUser setup function failed");
        if (status != noErr)
            goto exit;
        /*
         * Grab some information for the loops that follow.
         * printDevice is the printing device. This is only interesting for
         * ImageWriter (StyleWriter?) compatibility, and hasn't been tested
         * in many years.
         */
        printDevice = ((**hPrint).prStl.wDev >> 8) & 0xFF;
        draftMode = (**hPrint).prJob.bJDocLoop == bDraftLoop;
        if (draftMode && printDevice == kImageWriter)
            nCopies = (**hPrint).prJob.iCopies;
        else {
            nCopies = 1;
        }
        /*
         * Printing begins here.
         */
        printPort = PrOpenDoc(hPrint, NULL, NULL);
        docIsOpen = TRUE;
        status = PrError();
        CHECK(status, "\pCan't open document to print");
        CheckError(status);
        /*
         * Note: if you select "Print to EPS file", you can only image
         * one page, the first in this case.
         */
        for (iCopy = 1; iCopy <= nCopies; iCopy++) {
            for (pageNumber = (**hPrint).prJob.iFstPage;
                    pageNumber <= (**hPrint).prJob.iLstPage;
                    pageNumber++) {
                SetCursor(*GetCursor(watchCursor));
                PrOpenPage(printPort, NULL);
                status = PrError();
                if (status == noErr) {
                    pageRect = (**hPrint).prInfo.rPage;
                    status = (*twistDownPrintImageProc)(
                                theList,
                                hPrint,
                                clientData,
                                dateString,
                                &pageRect,
                                pageNumber
                            );
                }
                PrClosePage(printPort);
                if (status == noErr)
                    status = PrError();
                CHECK(status, "\pPrint page error");
                CheckError(status);
            }
        }
        /*
         * Normal exit
         */
        SetPort(savePort);
        PrCloseDoc(printPort);
        docIsOpen = FALSE;
        status = PrError();
        CHECK(status, "\pCan't close document after printing complete");
        CheckError(status);
        if (draftMode == FALSE) {
            PrPicFile(hPrint, NULL, NULL, NULL, &printStatus);
            status = PrError();
            CHECK(status, "\pCan't spool document after printing complete");
        }
        /*
         * Everyone exits here.
         */
exit:    SetPort(savePort);
        if (docIsOpen)
            PrCloseDoc(printPort);
        if (printIsOpen)
            PrClose();
        if (twistDownPrintExitProc != NULL)
            status = (*twistDownPrintExitProc)(theList, clientData, status);
        InitCursor();
        return (status);
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * DefaultTwistDownPrintSetupProc
 *
 * This will be called if the user didn't provide a print setup procedure. Our
 * default output page will have the date on the top-left and the page number on
 * the top right (both in 9 pt Helvetica Bold). This function must set the actual
 * number of pages that are to be printed.
 *
 * Note: the print functions have not been upgraded for right-to-left languages.
 */
static pascal OSErr
DefaultTwistDownPrintSetupProc(
        ListHandle                theList,
        THPrint                    hPrint,
        void                    *clientData,
        StringPtr                dateString
    )
{
        unsigned short            lineHeight;
        unsigned short            linesInPrintout;
        unsigned short            linesPerPage;
        unsigned short            nPages;
        unsigned short            headerHeight;
        Rect                    printRect;
        FontInfo                info;
        short                    fontNumber;

        UNUSED(clientData);
        UNUSED(dateString);
        SetPort(LIST.port);
        GetFNum(kPrintoutHeaderFont, &fontNumber);
        TextFont(fontNumber);
        TextSize(kPrintoutHeaderFontSize);
        GetFontInfo(&info);
        headerHeight = info.ascent + info.descent + info.leading;
        /*
         * Get the display page rectangle, remove the header, and determine
         * the number of lines that will fit on one page and, from that,
         * the number of pages in the printout. If this is less than the
         * default (999), adjust the print record.
         */
        printRect = (**hPrint).prInfo.rPage;
        printRect.top += (headerHeight + kPrintoutHeaderGap);
        linesInPrintout = height(LIST.dataBounds);
        TextFont(PRIVATE.fontNumber);
        TextSize(PRIVATE.fontSize);
        TextFace(normal);
        GetFontInfo(&info);
        lineHeight = info.ascent + info.descent + info.leading;
        linesPerPage = height(printRect) / lineHeight;
        nPages = (linesInPrintout + linesPerPage - 1) / linesPerPage;
        /*
         * We want to print nPages. Set this into the print record if the
         * caller asked for more (i.e. for the default "all pages").
         */
        if ((**hPrint).prJob.iLstPage > nPages)
            (**hPrint).prJob.iLstPage = nPages;
        return (noErr);
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * DefaultTwistDownPrintImageProc
 *
 * Image the current page. This must duplicate some of the code from the
 * print setup function (above). This needs work for right-to-left languages.
 *
 * The page is imaged using the currently selected display font and font size.
 */
static pascal OSErr
DefaultTwistDownPrintImageProc(
        ListHandle                theList,
        THPrint                    hPrint,
        void                    *clientData,
        StringPtr                dateString,
        const Rect                *pageRect,
        short                    pageNumber
    )
{
        unsigned short            i;
        unsigned short            lastRow;
        unsigned short            linesPerPage;
        unsigned short            headerHeight;
        Rect                    printRect;
        short                    lineHeight;
        Cell                    listCell;
        FontInfo                info;
        short                    fontNumber;
        Str255                    work;
        short                    cellSize;
        TwistDownHdl            twistDownHandle;
        register TwistDownPtr    twistDownPtr;
        signed char                elementLockState;

        UNUSED(clientData);
        UNUSED(hPrint);
        /*
         * First, image the header.
         */
        GetFNum(kPrintoutHeaderFont, &fontNumber);
        TextFont(fontNumber);
        TextSize(kPrintoutHeaderFontSize);
        TextFace(kPrintoutHeaderStyle);
        GetFontInfo(&info);
        headerHeight = info.ascent + info.descent + info.leading;
        MoveTo(pageRect->left, pageRect->top + info.ascent);
        DrawString(dateString);
        pstrcpy(work, "\pPage: ");
        i = work[0];
        NumToString(pageNumber, &work[i]);
        work[0] += work[i];
        work[i] = ' ';
        MoveTo(pageRect->right - StringWidth(work), pageRect->top + info.ascent);
        DrawString(work);
        printRect = *pageRect;
        printRect.top += (headerHeight + kPrintoutHeaderGap);
        /*
         * Now, do the list data itself.
         */
        TextFont(PRIVATE.fontNumber);
        TextSize(PRIVATE.fontSize);
        TextFace(normal);
        GetFontInfo(&info);
        lineHeight = info.ascent + info.descent + info.leading;
        linesPerPage = height(printRect) / lineHeight;
        listCell.h = 0;
        listCell.v = (pageNumber - 1) * linesPerPage + LIST.dataBounds.top;
        lastRow = listCell.v + linesPerPage;
        if (lastRow > LIST.dataBounds.bottom)
            lastRow = LIST.dataBounds.bottom;
        printRect.bottom = printRect.top + lineHeight;
        while (listCell.v < lastRow) {
            cellSize = sizeof twistDownHandle;
            LGetCell(&twistDownHandle,    &cellSize, listCell, theList);
            if (cellSize == sizeof twistDownHandle && twistDownHandle != NULL) {
                elementLockState = HGetState((Handle) twistDownHandle);
                HLock((Handle) twistDownHandle);
                twistDownPtr = (*twistDownHandle);
                (PRIVATE.drawProc)(theList, twistDownPtr, &printRect);
                HSetState((Handle) twistDownHandle, elementLockState);
            }
            OffsetRect(&printRect, 0, lineHeight);
            ++listCell.v;
        }
        return (noErr);
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * DefaultTwistDownDrawProc
 *
 * Draw the current list element in the viewRect. The caller has setup the font
 * information.
 */
static pascal void
DefaultTwistDownDrawProc(
        ListHandle                theList,            /* The list itself            */
        TwistDownPtr            twistDownPtr,        /* Locked data handle        */
        const Rect                *viewRect            /* Draw in this area        */
    )
{
        short                    textWidth;
#define ELEM (*twistDownPtr)

        if (PRIVATE.isLeftJustify)
            MoveTo(viewRect->left, viewRect->top + LIST.indent.v);
        else {
            textWidth = TextWidth(ELEM.data, 0, ELEM.dataLength);
            MoveTo(viewRect->right - textWidth, viewRect->top + LIST.indent.v);
        }
        DrawText(ELEM.data, 0, ELEM.dataLength);
#undef ELEM
}

static void
pstrcpy(
        StringPtr                dst,
        ConstStr255Param        src
    )
{
        BlockMoveData(src, dst, src[0] + 1);
}

static void
pstrcat(
        StringPtr                dst,
        ConstStr255Param        src
    )
{
        short                    length;

        length = 255 - dst[0];
        if (length > src[0])
            length = src[0];
        BlockMoveData(&src[1], &dst[1] + dst[0], length);
        dst[0] += length;
}