Letters

By David E. Smith, Editor & Publisher, MacTutor

Another Way To Post Events

Matthew Snyder

In reference to Joel McNamara’s article in the July issue, there’s another way to post command key events, but you wouldn’t know about it unless you’d read a somewhat obscure 1 page chapter in Inside Macintosh Vol. IV. PPostEvent posts an event just like PostEvent, but it “returns a pointer to the created queue entry.”

Here’s an example of its use. Like Joel, I needed to post an event and then fix the modifier field. This is an FKEY I wrote because too many times I found myself in a situation (like a dialog box) where ordinary paste did not work. Because the command and shift keys are down while the FKEY executes, just using PostEvent would result in all the posted events being command-shifted.

/* 1 */

#include<EventMgr.h>
#include <OSUtil.h>

main() {
 long length, offset;
 int index;
 char **tHandle;
 char *tPtr;
 EvQElPtr MyEventPtr;

if (TEGetScrapLen() > 0) {
 ZeroScrap();
 TEToScrap();
 }

tHandle = (char **) NewHandle(0);
length = GetScrap(tHandle, ‘TEXT’, &offset);
if (length > 0) {
 HLock(tHandle);
 tPtr = *tHandle;
 for (index = 0; index < length; index++) {
 PPostEvent((short) keyDown, (int) tPtr[index], &MyEventPtr);
 MyEventPtr_>evtQModifiers = 0;
 }
 }

DisposHandle(tHandle);
}

By the way, I very much liked Joel’s sentiment that as programmers we can rise above the mere end user; we’re not at the mercy of the “software gods.” It is a good feeling.

Take A Bow, Joel

I. Peter Sealy

I have just purchased a copy of MacTutor (June 1989) on the advice of the Lightspeed C user’s manual, and it has proved very valuable. I was especially impressed by Joel West’s “20 Steps to Printing Incompatibility” which explained maybe 50% of the problems we have had with the Mac. In particular, Excel’s infuriating refusal to work with anything but virgin memory (extremely annoying when you have an expensive 4MB sitting there vacant). More software houses should adopt Joel’s sensitivity to the amount of money that users have spent on their systems.

LSC vs. MPW

Andy Baird

Will Flor (“MPW vs. LSC,” MacTutor June 1989) is of course entitled to his opinions about the relative merits of MPW and Lightspeed C, but I had to laugh when he compared LSC to a tricycle and said “For very simple programs, perhaps LSC works adequately.” In case you’re unaware of it, Mr. Flor, a few of the “very simple” programs created with LSC are FoxBASE Mac, PageMaker and Digital Darkroom. If those are simple, I’d hate to see what you think is complex!

Hex Conversion

Temple M. Sarles

I enjoyed inputting and getting to run the “ADB Demo” for LS pascal 2.0 from your volume 5 number 3 in March 1989. Programs like these give dabblers like me some necessary insight into interfacing with the toolbox and really making things work.

It was a bit of a disappointment to find in procedure QuerySystem the line “str1 := concat(‘System Version (must convert to hex) = ‘, str2, chr(13));”. (emphasis added) Well, I did. Enclosed find the listing of a test program with the function ToHex which accepts a long integer and returns a string representing the value in hexadecimal. I think the code with its comments pretty well explains itself. There were two surprises. I idly tried a negative number, only to get unexpected results. I forgot that negative numbers are represented in two’s complement. An easy solution using the toolbox is presented in lines 21 & 22.

Not really solved is the need to make the string of hex digits a variable instead of a constant. If Hex_Char = ‘0123456789ABCDE’ is declared as a constant then line 27 ( , Hex_Char [Work + 1] ) gets a compile error of “Too many indices are being applied to a variable or expression.” The reason for this is not clear, but making it a string variable works well enough.

To apply this to ADB Demo, add function ToHex to MyADBStuff in the IMPLEMENTATION section ahead of procedure QuerySystem. In QuerySystem, replace the lines:

 NumToString(LongInt(theWorld.systemVersion), str2, chr(13));
 str1 := concat(‘System Version (must convert to hex) = ‘, str2, chr(13));

with:

{2}

 str2 := ToHex(LongInt(theWorld.systemVersion));  {convert to hex string}
 str2 := concat(copy(str2, 1, length(str2) - 2),
 ‘.’, copy(str2, length(str2) - 1, 2));{put in period}
 str1 := concat(‘System Version = ‘, str2, chr(13));

Appropriate credit should be given to Think Technology for their excellent implementation of Pascal and especially for their outstanding development environment (DEC & Apollo could take lessons).

{3}

program Test;    {Just a place to try things out}
 var
 T1: integer;    {The value as an integer}
 T2: string;{What it looks like as a string}

 function ToHex (Number_In: LongInt): string;      {This does the job}
 var
 Accumulate: string; {I never work into return value}
 Hex_Char: string; {The set of Hexadecimal digits}
 Shift: Integer; {Offset into the LongInt}
 Suppress_Zero: boolean;  
 {A switch to suppress leading zeroes}
 Work: LongInt;  {The clipped byte from the Number_In}

 begin
 Accumulate := ‘’; {Start with a blank string}
 Hex_Char := ‘0123456789ABCDEF’; 
 {Somehow this doesn’t work as a Const}
 Suppress_Zero := True; 
 {To start with suppress leading zeroes}

{First take care of sign bit, dispose of two’s complement }
{ and then deal with short three bit high-order hex number}

 if BitTst(@Number_In, 0) then{The sign bit is set!}
 begin
 Accumulate := ‘-’;
 Number_In := BitNot(Number_In); 
 {Two’s Complement cleared}
 Number_In := Number_In + $1
 {It’s always one shy - back to DP101}
 end;
 Work := BitShift(Number_In, 1);   
 {Bang to left  - IM/I-472}
 Work := BitShift(Work, -29); 
 {Back to right - IM/I-472}
 if Work > 0 then
 Accumulate := concat(Accumulate, Hex_Char[Work + 1]);

 Shift := 4;{Start with bit 5 - the 2nd digitd}
 repeat {Now a loop for the other 7 digitd}
 Work := BitShift(Number_In, shift); 
 {Bang to left  - IM/I-472}
 Work := BitShift(Work, -28); 
 {Back to right - IM/I-472}
 if Suppress_Zero then
 if Work > 0 then {The beginning of what we want}
 begin
 Suppress_Zero := False;  
 {A digit - No more leading zeroes}
 Accumulate := concat(Accumulate, Hex_Char[Work + 1])
 end
 else   {Don’t do anything!!}
 else
 Accumulate := concat(Accumulate, Hex_Char[Work + 1]);
 Shift := Shift + 4; {Move over one byte}
 until Shift = 32; {Bit 33 is out of bounds}

 ToHex := Accumulate {Put the result into return value}
 end;   {of function ToHex}

begin
 T1 := 1538;{A famous number now-a-days}
 T2 := ToHex(LongInt(T1));{Let’s see what it is}

{The next line inserts the period needed to make theWorld.systemVersion 
human readable}

 T2 := concat(copy(T2, 1, length(T2) - 2), ‘.’, copy(T2, length(T2) - 
1, 2));
 writeln(‘T1 = ‘, T1, ‘:  T2 = ‘, T2)
end.    {of program Test}

Fill Rectangle Tool

Kevin Parichan

In the article I wrote showing how to do the Spray Can and Paint Bucket tools I mentioned that there was a unit on GEnie that implemented these and other tools. That unit is no longer available, so I thought that I would give away the source for the standard filled rectangle tool. I rewrote the code in C so as to show that I don’t play favorites. With the routine given as is, you can easily modify it for ovals and round rectangles, filled or not. The routine uses the current grafport to get the fill pattern and the widths for the frame. Enjoy.

/* 4 */

#define NULL0L

Ptr NewBitMap(theBitMap,theRect)
   BitMap *theBitMap;
   Rect *theRect;
{
   theBitMap->rowBytes = ((theRect->right - theRect->left + 15) / 16) 
* 2;
   theBitMap->baseAddr = NewPtr(theBitMap->rowBytes * (theRect->bottom 
- theRect->top));
   theBitMap->bounds = *theRect;
   if (MemError() == noErr)
      return(theBitMap->baseAddr);
   return(NULL);
}

RectTool_Filled(where,workRect)
   Pointwhere;
   Rect *workRect;
{
   GrafPtrworkPort;
   BitMap workBits;
   PenState workState;
   BitMap oldBits,tempBits;
   Rect tempRect,theRect,aRect;
   PointnewLoc,pivot;
   long position;
   
   GetPort(&workPort);
   workBits = workPort->portBits;
   
   if (NewBitMap(&oldBits,workRect) == NULL)
      return;
   if (NewBitMap(&tempBits,workRect) == NULL)
   {
      DisposPtr(oldBits.baseAddr);
      return;
   }
   
   CopyBits(&workBits,&oldBits,workRect,workRect,srcCopy,NULL);
   
   tempRect = *workRect;
   tempRect.right = tempRect.right + 1;
   tempRect.bottom = tempRect.bottom + 1;
   
   GetPenState(&workState);
   PenNormal();
   PenSize(workState.pnSize.h,workState.pnSize.v);
   
   pivot = newLoc = where;
   SetRect(&theRect,where.h,where.v,where.h,where.v);
   
   while (Button()) {
      GetMouse(&newLoc);
      position = PinRect(&tempRect,newLoc);
      newLoc.v = HiWord(position);
      newLoc.h = LoWord(position);
      if (!EqualPt(newLoc,where))
      {
         Pt2Rect(newLoc,pivot,&theRect);
         Pt2Rect(where,pivot,&aRect);
         UnionRect(&theRect,&aRect,&aRect);
         CopyBits(&oldBits,&tempBits,workRect,workRect,srcCopy,NULL);
         SetPortBits(&tempBits);
         FillRect(&theRect,workState.pnPat);
         FrameRect(&theRect);
         SetPortBits(&workBits);
         CopyBits(&tempBits,&workBits,&aRect,&aRect,srcCopy,NULL);
         where = newLoc;
      }
   }
   
   DisposPtr(tempBits.baseAddr);
   DisposPtr(oldBits.baseAddr);
   SetPenState(&workState);
}

Stop The Press!

Kirk Chase

Well, the Splitbar CDEF indicator dragging bug is fixed, thanks to Alexander S. Colwell of Redondo Beach, CA andMurat N. Konar of Minneapolis, MN. Each one suggests that the Quickdraw global DragPattern at $A34 should be stuffed with a gray pattern. Murat suggests this be done in the initialization procedure, and Alexander says in the doCalc procedure when the thumb region is requested.

It seems that the varialble is initialized to black instead of gray as the Window Manager implies in Inside Macintosh Vol. I on page 294 and 295. It states that " DragGrayRgn pulls a dotted (gray) outline of the region around " and "If you want the region's outline to be drawn in a pattern other than gray, you can store the pattern in the global varialbe DragPattern and then invoke the macro _DragTheRgn." But it looks as if the standard CDEF initializes the global even though we are told by Apple not to write to low memory globals. Oh, well. Hopefully this bug(?) will be fixed later on.

On a side note, I became a father for the first time on July 10, 1989 at 11:36 AM. My wife gave birth to a 5lb. boy named, "Brandon Lee Chase." I like to thank those, especially the staff at MacTutor, for putting up with me at this time. I would also like to thank my wife, Sylvia Lue, for putting up with me. I married simply the best.