Dragging Multiple Objects

By Jörg Langowski, MacTutor Editorial Board

“C++/MacApp - dragging multiple objects”

We’ll continue the C++/MacApp drawing example this month, which we had left off in V6#12. As promised, although a little late because of the intervening Fortran review, we’ll add multiple shape selections. Also, we’ll define some different shapes, so that we don’t have to draw boring boxes all the time.

As before, the example code contains only those routines and definitions that have been changed with respect to the last example; reprinting the whole example each time would take up too much space. You’ll find the full code on the source code disk.

Shape subclasses

The easy part first: we’ll define some subclasses of TBox that correspond to ovals, rectangles and rounded rectangles. Common to all these objects is that their frame and contents will be drawn with certain patterns and a certain pen size, so we derive one new subclass of TBox, TShape, which contains the instance variables fPenSize, fPenPat and fFillPat.

There is also a new instance variable in the TBox class, fSelected; if I had designed the example properly from the start, we would never have to touch our subclasses again, but you see a program being developed here. So we’ll add this new instance variable; TBox will be our general class that corresponds to any object displayed in our window, occupying a certain space (fLocation) and being selected or not (fSelected).

From TShape, we derive three subclasses: TRect, TOval and TRoundRect. Of these, TRoundRect needs two more new instance variables to describe the corner curvature. We’ll define the new drawing methods (listing 2), and initializations for TBox and TShape [note that a Pattern is actually an 8-byte array and has to be copied explicitly, as shown in TShape::IBox]. In TBox::DrawShape, we’ll also check whether the shape has been selected and draw a black frame around it if so.

The CalcDiskSpace methods have to be modified to include the space for the new instance variables. I have, however, not yet changed the Read and Write methods to include the new information; therefore, Open and Save will not work as expected yet. We’ll work on that in a later column.

This would be all we need to do to work with the new shape objects, except that so far there is no way to draw them. We have to include three new selections in the palette; this is done by modifying code in TTEApplication and TPaletteView (see Listing 2). Later, we could make the code a little more general here and include a variable that defines the number of selections in the palette. Three new icons are included in the TEDrag.rsrc file (source code disk). Finally, TSketcher::TrackMouse had to be modified to include the new shapes.

Selecting and dragging multiple shapes

The main modification to our example is the selection of multiple shapes, like in MacDraw, and simultaneous dragging. For this we have to modify the TDragger and TSketcher command objects.

The way selections take place in our example is implemented in TSketcher::DoMouseCommand (see listing):

When you have chosen a drawing tool (rectangle, round rectangle or oval) from the palette, and click on an object that already exists, it will be selected (indicated by a black rectangular frame). When you click on another object, that object will be selected and the previous one deselected. Holding down the Shift key allows you to click on other objects and select/deselect them, without affecting the objects already selected. Clicking on one of the selected objects without the Shift key allows you to drag the selection.

How do we drag a multiple selection? (See TDragger::DoMouseCommand in the listing). For the drag feedback, we would like to have something like in MacDraw; an outline of all the shapes being drawn. Therefore, we first create a region that contains all the shapes, save the region handle, and create a picture that draws the outline of that region in patXOr mode. That will be our feedback picture.

For doing and undoing the command, we need to save the total distance that the selection has been moved in the new instance variable fDelta. We have to play around again with a global procedure, MoveSelected, that is passed to the ForEachShapeDo method as a parameter. How C++ simulates the Pascal way of passing procedures as parameters has been described in V6#11.

That’s all. Note that, although the example listing is again rather long, we did not have to touch most of the code, one of the advantages of MacApp. In the next of these articles, we’ll straighten out the disk I/O and maybe add some more bells and whistles to the drawing part of the program. Also, sometime we’ll modify the text edit part, so that our text is written in a nice box, draggable and resizeable.

NEON news

For you faithful Forth readers: It has finally happened, NEON is now in the public domain. But it’s not called NEON anymore. Here’s what Bob Loewenstein wrote over the network:

After a long negotiation period with Kriya Systems, I have received written permission to release Neon into the public domain. The letter from Kriya reads:

“Kriya Systems, Inc. gives you [me] the permission to freely distribute for scientific and educational purposes the programming language formerly known as Neon, including the distribution of the source which has been released to you. You do not have the right to use the name Neon, as it apparently had prior use by another company and is not a valid trademark of Kriya Systems. All commercial distribution rights are reserved by Kriya Systems, Inc.”

Since a few of us at the University of Chicago have modified the language somewhat, and to comply with Kriya’s wishes, we have renamed the language Yerk, which is at least not an acronym for anything, but rather stands for Yerkes Observatory, part of the Department of Astronomy and Astrophysics at U of C. [I’m pleased to note that “Yerk” also corresponds more or less to the German pronunciation of my name - JL].

For those who don’t know about Neon, it was an object oriented, Macintosh targeted language based on a Forth Kernel with some major modifications. It was developed and sold as a product by Kriya Systems from 1985 to 1988. Because it is an extensible language, it was possible for us to keep it compatible with new toolkit calls, new Mac managers, etc. We have modified the nucleus to make improvements, but it is still an evolving language. We are releasing it at this time because it is a very useable and powerful language/environment for the mac.

We have written many data acquisition and display programs with Yerk, as well as graphical interfaces for instrument control (both telescopes and instruments). While not part of this release, we have written interfaces for Color Quickdraw for image processing programs, and a MacTCP interface for network interface. These and other interfaces will probably be made available on request, with the understanding that they were written for specific applications and not as general support interfaces.

Some features of the language are:

- defaulted early binding, with ability to late bind in almost any circumstance

- inheritance (not multiple)

- floating point (SANE)

- many system classes and objects for Mac interfacing:

windows, controls, events, files, arrays, ordered-columns, menus, hierarchical and popup menus, handles, strings, mouse, Quickdraw, modal dialogs, offscreen bitmaps, VBL, time manager, etc.

- module (overlay) creation that are loaded only when necessary and may be purged from application heap memory.

Some forth extensions are:

- local input parameters

- named input variables

- multiple cfa words (including vectors and values)

- CASE

- SELECT

- 68000 assembler

We have used the language on the following macs:

Mac+,SE,SE30,MacII,IIci,IIx,IIcx. There is no reason to believe that it won’t work on any Mac+ or beyond. Any system >= 6.0 is recommended.

The complete source files, an executable Yerk environment, and update manual (MS Word 4.0 format) are available with anonymous ftp at oddjob.uchicago.edu in ~ftp/pub/Yerk directory. They are compressed with Stuffit and then binhexed. Please try to download these files in the evening hours. In the near future, these files may be added to the MacTutor source code disk.

If anyone has any questions, feel free to contact me:

Bob Loewenstein

-- the end of Bob’s letter --

I have requested the Yerk files through network mail. They are rather long, and I don’t know whether they will arrive in time to be put on the source code disk before this month’s deadline. Anyway, they’ll be available in the near future. Again, if you have problems accessing the ftp server, you can drop me E-mail at langowski@frembl51.bitnet.

See you again next month.

Listing 1: Changes in TEDrag.h after V6#12

class TBox : public TObject {
public:
 Rect fLocation;
 BooleanfSelected;
 virtual pascal void IBox(Rect *itsLocation);
 virtual pascal void DrawShape();
 virtual pascal void NeedDiskSpace(long *data);
 virtual pascal void Read(short aRefNum);
 virtual pascal void Write(short aRefNum);
#ifdef qDebug
 virtual pascal void Fields(pascal void (*DoToField) 
 (StringPtr fieldName, Ptr fieldAddr,
 short fieldType, void *link), void *link);
#endif
};

class TShape : public TBox {
public:
 short  fPenSize;
 PatternfPenPat;
 PatternfFillPat;
 virtual pascal void NeedDiskSpace(long *data);
 virtual pascal void IBox(Rect *itsLocation);

#ifdef qDebug
 virtual pascal void Fields(pascal void (*DoToField) 
 (StringPtr fieldName, Ptr fieldAddr,
 short fieldType, void *link), void *link);
#endif
};

class TRect : public TShape {
public:
 pascal void DrawShape();
 pascal void NeedDiskSpace(long *data);
#ifdef qDebug
 virtual pascal void Fields(pascal void (*DoToField) 
 (StringPtr fieldName, Ptr fieldAddr,
 short fieldType, void *link), void *link);
#endif
};

class TOval : public TShape {
public:
 pascal void DrawShape();
 pascal void NeedDiskSpace(long *data);
#ifdef qDebug
 virtual pascal void Fields(pascal void (*DoToField) 
 (StringPtr fieldName, Ptr fieldAddr,
 short fieldType, void *link), void *link);
#endif
};

class TRoundRect : public TShape {
public:
 short  fOvalWidth;
 short  fOvalHeight;
 
 pascal void IBox(Rect *itsLocation);
 pascal void DrawShape();
 pascal void NeedDiskSpace(long *data);
#ifdef qDebug
 virtual pascal void Fields(pascal void (*DoToField) 
 (StringPtr fieldName, Ptr fieldAddr,
 short fieldType, void *link), void *link);
#endif
};

class TDragger : public TCommand {
public:
 TTEDocument   *fTEDocument;
 TTextView*fTextView;
 TBox   *fBox;
 Rect   oldLocation; 
 Rect   newLocation; PointfDelta;  // offset moved
 PicHandlefFeedbackPicture; Rect   fPictureBounds;

pascal void IDragger (TBox *itsBox, 
 TTEDocument *itsDocument, TTextView *itsView);
 pascal struct TCommand *TrackMouse
 (TrackPhase aTrackPhase, VPoint *anchorPoint, 
 VPoint *previousPoint, VPoint *nextPoint, 
 Boolean mouseDidMove);
 pascal void TrackFeedback(VPoint *anchorPoint, 
 VPoint *nextPoint, Boolean turnItOn, 
 Boolean mouseDidMove);
 pascal void DoIt();
 pascal void RedoIt();
 pascal void UndoIt();
#ifdef qDebug
 virtual pascal void Fields(pascal void (*DoToField) 
 (StringPtr fieldName, Ptr fieldAddr, 
 short fieldType, void *link), void *link);
#endif
};

// -- global definitions --

// support for dragging, JL 9/90
struct FindBoxStruct {
 Point theMouse;
 TBox *myBox;
};

// support for selections, JL 1/91
struct SelectStruct {
 TTextView *myTextView;
};

// support for moves, JL 1/91
struct MoveStruct {
 Point delta;
};

Listing 2: Changes in TEDrag.cp after V6#12

pascal void TBox::IBox(Rect *itsLocation)
 {    fLocation = *itsLocation;  
 fSelected = false;}

pascal void TBox::DrawShape()
{if (fSelected)
 { PenSize (1,1);
 ForeColor(blackColor);
 FrameRect(&fLocation);   ForeColor(kBoxColor);   }
}

pascal void TBox::NeedDiskSpace(long *data)
{data = data + sizeof(fLocation) + sizeof(fSelected);
}

#ifdef qDebug
pascal void TBox::Fields
 (pascal void (*DoToField) (StringPtr fieldName,
 Ptr fieldAddr, short fieldType, void *link), void *link)
{
 DoToField(“\pTBox”, nil, bClass, link);
 DoToField(“\pfLocation”, (Ptr) &fLocation, bRect, link);
 DoToField(“\pfSelected”, 
 (Ptr) &fSelected, bBoolean, link);
 inherited::Fields(DoToField, link);
}
#endif

pascal void TShape::NeedDiskSpace(long *data)
{inherited::NeedDiskSpace(data);
 data = data + sizeof(fPenSize) 
 + sizeof(fPenPat) + sizeof(fFillPat);
}

pascal void TShape::IBox(Rect *itsLocation)
 { fLocation = *itsLocation;  
 fPenSize = 1;
 
 for (int i = 0; i<8 ; i++)
 { fPenPat[i]  = qd.black[i];
   fFillPat[i] = qd.gray[i];   }
 inherited::IBox(itsLocation);
 }

#ifdef qDebug
pascal void TShape::Fields
 (pascal void (*DoToField) (StringPtr fieldName,
 Ptr fieldAddr, short fieldType, void *link), void *link)
{
 DoToField(“\pTShape”, nil, bClass, link);
 DoToField(“\pfPenSize”, 
 (Ptr) &fPenSize, bInteger, link);
 DoToField(“\pfPenPat”,
 (Ptr) &fPenPat, bPattern, link);
 DoToField(“\pfFillPat”, (Ptr) &fFillPat, bPattern, link);
 inherited::Fields(DoToField, link);
}
#endif

pascal void TRect::DrawShape()
{PenSize (fPenSize,fPenSize);
 PenPat (fPenPat);
 FillRect(&fLocation,fFillPat);
 FrameRect(&fLocation);
 inherited::DrawShape();
}

pascal void TRect::NeedDiskSpace(long *data)
{inherited::NeedDiskSpace(data);
}

#ifdef qDebug
pascal void TRect::Fields
 (pascal void (*DoToField) (StringPtr fieldName,
 Ptr fieldAddr, short fieldType, void *link), void *link)
{
 DoToField(“\pTRect”, nil, bClass, link);
 inherited::Fields(DoToField, link);
}
#endif


pascal void TOval::DrawShape()
{PenSize (fPenSize,fPenSize);
 PenPat (fPenPat);
 FillOval(&fLocation,fFillPat);
 FrameOval(&fLocation);
 inherited::DrawShape();
}

pascal void TOval::NeedDiskSpace(long *data)
{inherited::NeedDiskSpace(data);
}

#ifdef qDebug
pascal void TOval::Fields
 (pascal void (*DoToField) (StringPtr fieldName,
 Ptr fieldAddr, short fieldType, void *link), void *link)
{
 DoToField(“\pTOval”, nil, bClass, link);
 inherited::Fields(DoToField, link);
}
#endif

pascal void TRoundRect::IBox(Rect *itsLocation)
 { fOvalWidth = 10;
 fOvalHeight = 10;
 inherited::IBox(itsLocation);
 }

pascal void TRoundRect::DrawShape()
{PenSize (fPenSize,fPenSize);
 PenPat (fPenPat);
 FillRoundRect(&fLocation,
 fOvalWidth,fOvalHeight,fFillPat);
 FrameRoundRect(&fLocation,
 fOvalWidth,fOvalHeight);
 inherited::DrawShape();
}

pascal void TRoundRect::NeedDiskSpace(long *data)
{inherited::NeedDiskSpace(data);
 data = 
 data + sizeof(fOvalWidth) + sizeof(fOvalHeight);
}

#ifdef qDebug
pascal void TRoundRect::Fields
 (pascal void (*DoToField) (StringPtr fieldName,
 Ptr fieldAddr, short fieldType, void *link), void *link)
{
 DoToField(“\pTRoundRect”, nil, bClass, link);
 DoToField(“\pfOvalWidth”, 
 (Ptr) &fOvalWidth, bInteger, link);
 DoToField(“\pfOvalHeight”, 
 (Ptr) &fOvalHeight, bInteger, link);
 inherited::Fields(DoToField, link);
}
#endif
pascal void TTEApplication::ITEApplication(OSType itsMainFileType)
{
 gColorArray[cBlack-cBlack] = blackColor; 
 gColorArray[cBlue-cBlack]  = blueColor;
 gColorArray[cGreen-cBlack] = greenColor;
 gColorArray[cRed-cBlack] = redColor;
 gColorArray[cWhite-cBlack] = whiteColor;
 SetRect(&gIconRect[kBox-kBox], 0, 0, kIconWidth, kIconWidth); // left 
 top  right  bottom
 SetRect(&gIconRect[kText-kBox], kIconWidth, 0, 2 * kIconWidth, kIconWidth);
 SetRect(&gIconRect[kRect-kBox], 2 * kIconWidth, 0, 3 * kIconWidth, kIconWidth); 

 SetRect(&gIconRect[kRRect-kBox], 3 * kIconWidth, 0, 4 * kIconWidth, 
kIconWidth);
 SetRect(&gIconRect[kOval-kBox], 4 * kIconWidth, 0, 5 * kIconWidth, kIconWidth); 

 IApplication(itsMainFileType);

 InitPrinting();
}

pascal void TPaletteView::Draw(Rect *area)
{
 Rect aFrame;
 Point  aPenSize;
 Handle aHandle;
 
 ForeColor(kPaletteColor);
 
 aHandle = GetIcon(kBoxIconID);
 FailNILResource(aHandle);
 PlotIcon(&gIconRect[kBox-kBox], aHandle);
 
 aHandle = GetIcon(kTextIconID);
 FailNILResource(aHandle);
 PlotIcon(&gIconRect[kText-kBox], aHandle);
 
 aHandle = GetIcon(kRectIconID);
 FailNILResource(aHandle);
 PlotIcon(&gIconRect[kRect-kBox], aHandle);
 
 aHandle = GetIcon(kRRectIconID);
 FailNILResource(aHandle);
 PlotIcon(&gIconRect[kRRect-kBox], aHandle);
 
 aHandle = GetIcon(kOvalIconID);
 FailNILResource(aHandle);
 PlotIcon(&gIconRect[kOval-kBox], aHandle);
 
 ForeColor(blackColor);
 GetQDExtent(&aFrame);
 SetPt(&aPenSize, 1, 1);
 Adorn(&aFrame, aPenSize, adnLineBottom);
}

pascal struct TCommand 
 *TPaletteView::DoMouseCommand(Point *theMouse,
 EventInfo *info, Point *hysteresis)
{int  index;
 index = int(theMouse->h / kIconWidth);
 
 if ((index > 0) && (index < 5) 
 && (index != fIconSelected)) 
 { if (Focus()) { DoHighlightSelection(hlOn, hlOff);           
 };
 fIconSelected = index;
 if (Focus()) { DoHighlightSelection(hlOff, hlOn);             
 };
 };
 return gNoChanges;}

pascal void Deselect(TBox *aBox, SelectStruct *aSelectStruct)
{aBox->fSelected = false;
 aSelectStruct->myTextView->
 InvalidRect(&aBox->fLocation);  }

pascal struct TCommand 
 *TTextView::DoMouseCommand(Point *theMouse, 
 EventInfo *info, Point *hysteresis)
{  TSketcher *aSketcher;
 TDragger  *aDragger;
 FindBoxStruct aFindBoxStruct;
 SelectStruct aSelectStruct;
 
 if (fPaletteView->fIconSelected > kText-kBox) 
 {
 // dragging support, JL 9/90
 // multiple selections, JL 1/91
 aFindBoxStruct.theMouse = *theMouse;
 aFindBoxStruct.myBox = nil;
 aSelectStruct.myTextView = 
 fTEDocument->fTextView;
 
 fTEDocument->ForEachShapeDo
 ((DoToObject)FindBox,&aFindBoxStruct);
 
 if (aFindBoxStruct.myBox != nil)
 { 
 if (aFindBoxStruct.myBox->fSelected)
 {
 if (info->theShiftKey) 
 { aFindBoxStruct.myBox->fSelected
 = false;
 InvalidRect
 (&aFindBoxStruct.myBox->fLocation);
 return inherited::DoMouseCommand
 (theMouse,info,hysteresis);
 }
 else
 { aDragger = new TDragger;
 FailNIL(aDragger);
 aDragger->IDragger
 (aFindBoxStruct.myBox, 
  fTEDocument, this);
 return aDragger;
 }
 }
 else
 { if (!info->theShiftKey) 
 { fTEDocument->ForEachShapeDo
 ((DoToObject)Deselect,&aSelectStruct); }
 aFindBoxStruct.myBox->fSelected = 
 true;
 InvalidRect
 (&aFindBoxStruct.myBox->fLocation);
 return inherited::DoMouseCommand
 (theMouse,info,hysteresis);
 }
 }
 else
 { fTEDocument->ForEachShapeDo
 ((DoToObject)Deselect,&aSelectStruct);
 aSketcher = new TSketcher;
 FailNIL(aSketcher);
 aSketcher->ISketcher(fTEDocument, this);
 return aSketcher;
 }
 }
 else
 return inherited::DoMouseCommand
 (theMouse,info,hysteresis);
}

pascal void DrawYourself(TBox *aBox, void *link)
{
 aBox->DrawShape();
}

pascal struct TCommand 
 *TSketcher::TrackMouse(TrackPhase aTrackPhase,
 VPoint *anchorPoint, VPoint *previousPoint, 
 VPoint *nextPoint, Boolean mouseDidMove)
{Rect  newRect;  TBox  *aBox;
 
 if (aTrackPhase == trackRelease)
 { if (!EqualPt(fTextView->ViewToQDPt
 (anchorPoint),
 fTextView->ViewToQDPt(nextPoint)) )
 { Pt2Rect(
 fTextView->ViewToQDPt(anchorPoint), 
 fTextView->ViewToQDPt(nextPoint), 
 &newRect);

 switch (fTextView->
 fPaletteView->fIconSelected)
 { case kBox-kBox:
 case kRect-kBox:
 aBox = new TRect; break;
 case kRRect-kBox:
   aBox = new TRoundRect; break;
 case kOval-kBox:
 aBox = new TOval; break;
 default: aBox = nil;    }
 
 FailNIL(aBox);
 aBox->IBox(&newRect);
 fBox = aBox;    fBoxLocation = newRect;
 }
 else
 { return gNoChanges;    }
 }
 return this;
}

pascal void DrawSelected(TBox *aBox, void *link)
{
 if (aBox->fSelected)
 { aBox->fSelected = false;
 aBox->DrawShape();
 aBox->fSelected = true;  }
}

pascal void MoveSelected(TBox *aBox, MoveStruct    *aMoveStruct)
{if (aBox->fSelected)
 { OffsetRect(&aBox->fLocation,
 aMoveStruct->delta.h,
 aMoveStruct->delta.v);   }
}

pascal struct TCommand 
 *TDragger::TrackMouse(TrackPhase aTrackPhase,
 VPoint *anchorPoint, VPoint *previousPoint, 
 VPoint *nextPoint, Boolean mouseDidMove)
{void   *link; Rectr;
 RgnHandleoldClip; RgnHandle  DragRgn;
 PenState oldState; MoveStruct  aMoveStruct;
 
 if (aTrackPhase == trackPress)
 { oldClip = MakeNewRgn();
 DragRgn = MakeNewRgn();
 GetClip(oldClip);
 GetPenState(&oldState);

// create outline of shapes being drawn
 OpenRgn();
 fTEDocument->ForEachShapeDo
 ((DoToObject)DrawSelected,link);
 CloseRgn(DragRgn);

// get enclosing rectangle & make picture
 r = (*DragRgn)->rgnBBox;
 fFeedbackPicture = OpenPicture(&r);
 FailNIL(fFeedbackPicture);
 ClipRect(&r);
 PenNormal();
 PenMode(patXor);
 FrameRgn(DragRgn);
 ClosePicture();
 fPictureBounds = r;
// initialize old and new update rectangles
 oldLocation = r;
 newLocation = r;
// reset old states
 DisposeRgn(DragRgn);SetClip(oldClip);
 DisposeRgn(oldClip);
 SetPenState(&oldState);
 
 if (EmptyRect(&(*fFeedbackPicture)->picFrame))
 { KillPicture(fFeedbackPicture);
 fFeedbackPicture = nil;
 FailNIL(fFeedbackPicture);   }
 }

 if ((aTrackPhase == trackMove) && mouseDidMove)
 { fDelta = fTextView->ViewToQDPt(nextPoint);
 SubPt(fTextView->ViewToQDPt(previousPoint),
 &fDelta);
 OffsetRect(&fPictureBounds,fDelta.h,fDelta.v);
 }

 if ((aTrackPhase == trackRelease) 
 && mouseDidMove)
 { fDelta = fTextView->ViewToQDPt(nextPoint);
 SubPt(fTextView->ViewToQDPt(anchorPoint),
 &fDelta);
 
 if ((fDelta.h == 0) && (fDelta.v == 0))
 { return gNoChanges;   }
 OffsetRect(&newLocation,fDelta.h,fDelta.v);
 
 aMoveStruct.delta = fDelta;
 fTEDocument->ForEachShapeDo
 ((DoToObject)MoveSelected,&aMoveStruct);
 
 if (fFeedbackPicture != nil)  // being paranoid
 { KillPicture(fFeedbackPicture);
 fFeedbackPicture = nil;   }
 }
 return this;
}

pascal void TDragger::DoIt()
{
 fTextView->InvalidRect(&newLocation);
 fTextView->InvalidRect(&oldLocation);
}

pascal void TDragger::RedoIt()  
{  
 MoveStruct aMoveStruct;
 aMoveStruct.delta = fDelta;
 fTEDocument->ForEachShapeDo
 ((DoToObject)MoveSelected,&aMoveStruct);
 DoIt(); 
}

pascal void TDragger::UndoIt()
{
 MoveStruct aMoveStruct;
 aMoveStruct.delta.h = -fDelta.h;
 aMoveStruct.delta.v = -fDelta.v;
 fTEDocument->ForEachShapeDo
 ((DoToObject)MoveSelected,&aMoveStruct);
 DoIt(); 
}

#ifdef qDebug
pascal void TDragger::Fields
 (pascal void (*DoToField) (StringPtr fieldName,
 Ptr fieldAddr, short fieldType, void *link), void *link)
{
 DoToField(“\pTDragger”, nil, bClass, link);
 DoToField(“\pfTEDocument”, 
 (Ptr) &fTEDocument, bObject, link);
 DoToField(“\pfTextView”, 
 (Ptr) &fTextView, bObject, link);
 DoToField(“\pfBox”, (Ptr) &fBox, bObject, link);
 DoToField(“\poldLocation”, 
 (Ptr) &oldLocation, bRect, link);
 DoToField(“\pnewLocation”, 
 (Ptr) &newLocation, bRect, link);
 DoToField(“\pfDelta”, (Ptr) &fDelta, bPoint, link);
 DoToField(“\pfFeedbackPicture”, 
 (Ptr) &fFeedbackPicture, bHandle, link);
 DoToField(“\pfPictureBounds”,
 (Ptr) &fPictureBounds, bRect, link);
 inherited::Fields(DoToField, link);
}
#endif