TweetFollow Us on Twitter

File Package
Volume Number:1
Issue Number:7
Column Tag:MacPascal

Standard File Package, unpack & copy the bits

By Alan Wootton

Here is a program to view MacPaint documents from MacPascal (like “showpage”). I use the File Manager, the Standard File Package, the toolbox procedure UnPackBits, and QuickDraw’s CopyBits to display the image loaded in memory.

In MacTutor #5, Gary Palmer asked about loading MacPaint files in MacPascal. Well, I remembered once running across a description of MacPaint docs by Bill Atkinson. After some digging, I found the description in part of a mailing from tech support to developers dated Dec. 1983.

Atkinson explains that the resource fork is not used and that a 512 byte header precedes the packed bitmap data. The header is an array of patterns and some empty space. To simply view the picture we can ignore the header. The MacPaint ‘page’ is 720 lines of 72 bytes each. This is almost 51K and since we wish to load this into memory, a FatMac will probably be required. Atkinson gives a short routine to decode the data into a page. He uses UnpackBits, which is on page 7 of ToolBox Utilities.

Reading the data was a problem. I tried to use the file I/O routines provided with MacPascal. One must either read data byte-at-a-time, which takes forever, or, if you read large blocks, you can never get the last partially filled block. At this point I decided that Real Programmers use the low level File Manager routines. In other words PBOpen, PBRead, and then PBClose.

Another MacPascal shortcoming is the GetOldFile function. Once again, Real Programmers go straight past the limitations of the language and consult the bible (Inside Mac). We shall use the Standard File Package.

The Standard File Package

MacPascal’s function GetOldName will only select files of type TEXT. To select MacPaint docs it will be necessary to call the Standard File Package directly (OldPaintName in following program). On page 30 of Packages in “Inside Macintosh”, the procedure SFGetFile is described. To call it, use trap $A9EA, which is Pack3, and be sure to push a 2, the ‘selector’, on the stack last. You must type in the SFReply record on page 25. [For a complete description of SFReply, see the Assembly Column in this issue.] Since our type list will just be one type (PNTG) it will not be necessary to declare an array. Pass nil for filefilter and dlghook. There is an argument to pass a prompt string that Inside Mac says is historical only. I find that it works fine.

Low Level File Manager

The filecall interface in the following program simulates the PB calls of the File Manager. This is an example of the OS call I presented in MacTutor #6. [Please refer to issue #6 for details on calling OS routines from Pascal.] Before you can use the the PB routines, you must type the lengthy Parameter Block declarations. There are four variant parts to this record. I have only used the ioParam part here because that is all that was needed in this example. You should type the whole thing and save it somewhere for later use. Note that 8 bit types do not come out right, so one must take care that the declaration has the correct length. The routine descriptions (starting on page 31 of the File Manager) give a nice list of those parameters that must be set before calling (assembly programmers note: in some places ioRefNum is listed as 22, but the correct number is 24). You should carefully check that each parameter is set correctly before calling. The exception is ioCompletion, which can be ignored since we will be making synchronous calls. If ioNamePtr is not nil then the File Manager assumes that its value is the address of a string. This could badly mess up memory. In MacPascal, declared variables are cleared to 0’s so you can get away with this, but later, when you compile, nasty bugs pop up (this actually happened to me).

UnPackBits

UnPackBits is actually very simple. I have complicated things by not reading all the data into memory at once. The scheme used is to read 1024 bytes into memory (skipping the header) and when the first 512 bytes are used I slide the upper 512 bytes down and add 512 bytes onto the end. The program unpacks 72 bytes at a time for 720 lines. For faster operation you can unpack 4 lines at a time. Change 720 to 180 and 72 to 288.

After the page array is filled, it would be nice to take a look at it. Copybits is used to move the image onto the drawing window. The nice thing about copybits is that it will scale the image to fit. Simply setup a Quickdraw Bitmap record for page, set destrect to the desired size, and call copybits as shown. If you change 144 to 576 and 180 to 720 you can see the painting full size.

To write a MacPaint document (not done in this program) it is necessary to know the format of the header. The header is a 4 byte version number (default = 2) and then 38*8 = 304 bytes of patterns and then 204 unused bytes for a total of 512. However, Atkinson’s example writes 512 zeros for a header so I guess that would work. To pack the data you use the reverse of the unpack procedure. Things can be made simpler though because you can use one destination buffer and then write it out after every PackBits.

It is my contention that everything in Inside Mac can be demonstrated and used from MacPascal (except things like Vertical Retrace routines). If there is anything that you have trouble with and would like to see in MacTutor, write a letter to MacTutor and I will see if there isn’t a way to do it.


program Read_MacPaint_doc;{by Alan Wootton 4/85}
           { This program reads a MacPaint file and shows            
        the picture 1/4 size in Drawing }
 uses
  Quickdraw2;
 type
  ptr = ^integer;
  OStype = longint;

  SFReply = record { this is used by the standard file               
                           package, see Packages }
    good : integer;
    ftype : OSType;
    vrefNum : integer;
    version : integer;
    fname : string[63];
   end;

{ Parameter Block information contained in File Manager 
chapter of Inside Macintosh.  Note that MacPascal won’t do 8 bit fields 
right }

  ParamBlkPtr = ^ParamBlockRec;
  ParamBlockRec = record
{ data structure of File Manager }
    qLink : Ptr;
    qType : integer;
    ioTrap : integer;
    ioCmdAddr : ptr;
    ioCompletion : ptr;
    ioResult : integer;
    ioNamePtr : ^str255;
    ioVrefNum : integer;
{  case ParamBlkType of  ...  ioParam:  }
    ioRefNum : integer;
{       ioVersNum : byte;  }
    ioPermssn : integer;{ byte }
    ioMisc : ptr;
    ioBuffer : ptr;
    ioReqCount : longint;
    ioActCount : longint;
    ioPosMode : integer;
    ioPosOffset : longint;
   end;

  diskBlock = packed array[0..511] of char;

  paintPage = array[0..35, 0..719] of integer;
{  576*720 bitmap  = 72 bytes * 720 lines =  51,840           bytes }




 var
  reply : SFReply;{ used by OldPaintName, declared here              
                   to access vRefNum }
  filename : str255;
  fileblock : ParamBlockRec;
  buff : array[0..1] of diskblock;{ 1K }

  Page : paintPage;{ Huge variable, almost 52K  }

  srcPnt : ^diskBlock;
  destPnt : ^paintPage;

  lines, err : integer;

  curport : Grafptr;
  pageBits : bitmap;
  destRect : Rect;


{ common OS trap code, could be done with ‘Generic’ call}
{see MacTutor Vol. 1 No. 6 for assembly source code}
 function filecall (Pb : ParamBlkPtr;
         trap : integer) : integer;
  var
   access : array[0..12] of integer;
   d0, a0 : longint;
 begin
  stuffHex(@access, ‘2848548C41FA000C309F245F265F20522013FFFF224826804ED4’);
  a0 := ord(pb);
  inlineP($4E75, @d0, @a0, trap, @access);
  filecall := loword(d0);
 end;

{ The following File Manager calls work just like   }
{ those described in Inside Macintosh for the Lisa Pascal Workshop.  
}
{ Except that the async parameter is a dummy; all calls are sync }

 function PBOpen (Pb : ParamBlkPtr;
         async : boolean) : integer;
 begin
  PBOpen := filecall(pb, $A000);
 end;

 function PBClose (Pb : ParamBlkPtr;
         async : boolean) : integer;
 begin
  PBClose := filecall(pb, $A001);
 end;

 function PBRead (Pb : ParamBlkPtr;
         async : boolean) : integer;
 begin
  PBRead := filecall(pb, $A002);
 end;


{  same as OldFileName, only for MacPaint docs }
 function OldPaintName (prompt : str255) : str255;
  var
   where : point;
   typelist : longint;
 begin
  reply.good := 0;
  typelist := $504E5447;{ ‘PNTG’ }
  setPT(where, 100, 100);
  inlineP($A9EA, where, @prompt, nil, 1, @typelist, nil, @reply, 2);
{ $A9EA is pack3 ,  2 is SFGetFile, see Packages  }
  if reply.good <> 0 then
   OldPaintName := reply.Fname
  else
   OldPaintName := ‘’;
 end;


{  This procedure moves buff[1] down onto buff[0], adjusts srcPnt to 
point at it’s same data and tacks more data on end in buff[1].     }
 procedure Refill_Buffer;
 begin
  blockmove(@buff[1], @buff[0], 512);
  srcPnt := pointer(ord(srcPnt) - 512);
  fileBlock.ioBuffer := @buff[1];
  fileBlock.ioReqCount := 512;
  fileBlock.ioPosMode := 0;
  err := PBRead(@fileBlock, false);{ fill buff[1] }
 end;


begin { main }
 ShowDrawing;
 fileName := OldPaintName(‘ Select Painting to examine’);
 while filename <> ‘’ do
  begin
   fileBlock.ioVrefNum := reply.vrefnum;
   fileBlock.ioNamePtr := @fileName;
   fileBlock.ioPermssn := 1;{ read only, version number              
                                   is in upper byte and is 0 }
   fileBlock.ioMisc := nil;
   if PBOpen(@fileBlock, false) = 0 then
    begin
     refill_buffer;{  first block is skipped }
     refill_buffer;{   fill 1 }
     refill_buffer;{ 1 onto 0, refill 1 }

     srcPnt := @buff[0];{ <-- pointer to start of data }
     destPnt := @Page;{ <----  pointer to Page bitmap }

{------> This is the part that actually decodes the packed MacPaint data 
<------}
{ $A8D0 is UnPackBits, see page 7 in Toolbox Utilities   }
{ srcPnt and destPnt are updated by UnPackBits so use @}
     for lines := 1 to 720 do{ 720 lines in paint doc }
      begin
       inlineP($A8D0, @srcPnt, @destPnt, 72);
                                     { UnPackBits for 72 bytes }
       if ord(srcpnt) >= ord(@buff[1]) then
        Refill_Buffer; { if src no longer in buff[0] }
      end;{ of 720 lines }

     if PBClose(@fileBlock, false) <> 0 then
      writeln(‘close error’);

{  now show drawing  in current port  (drawing window) }
     GetPort(curPort);

 
{  set up bitmap record }
    pagebits.baseaddr := pointer(ord(@page));
    pagebits.rowbytes := 72;
    setRect(pagebits.bounds, 0, 0, 576, 720);

     setRect(destRect, 0, 0, 144, 180);
{ 144,180 =1/4 normal, image will be squashed to fit }

     copyBits(pagebits, curport^.portbits, pagebits.bounds,          
           destRect, srcCopy, nil);
     moveto(4, 190);
     drawstring(‘Click to open another MacPainting’);
     repeat
     until button;

    end;{ if no Open error }
   fileName := OldPaintName(‘ Select another Painting ?’);
  end;{ if name<>’’ loop }
end.
 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Latest Forum Discussions

See All

How to evolve Eevee in Pokemon GO
By now, almost everyone should be hip to how to evolve Pokemon in Pokemon GO (and if not, there's a guide for that). Just gather enough candy of the appropriate type, feed them all to the Pokemon, and evolution happens. It's a miracle that would... | Read more »
CSR Racing 2: Guide to all game modes
It might not seem like there are all that many ways to go fast in a straight line, but CSR Racing 2 begs to differ. [Read more] | Read more »
Bulb Boy (Games)
Bulb Boy 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Multi-award winning 2D point & click horror adventure about a boy with a glowing head. | Read more »
5 top free emoji keyboard apps
If we're not at peak emoji yet as a society, it feels like we definitely should be. The emoji concept has gone far beyond what anyone in Japan could have envisioned when the people there unleashed it on an unsuspecting world, but the West has... | Read more »
How to unlock more characters in Disney...
One of the big charms of Disney Emoji Blitz is seeing a wide variety of beloved Disney and Pixar characters transformed into smiling emojis. Even someone like the sneaky Randall from Monsters Inc., who probably never cracked a smile on film, is... | Read more »
Cubway (Games)
Cubway 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Cubway is a journey with an abstract story of lifecycle of rebirth, called Samsara. Guide the cube through the long way full of dangers... | Read more »
Colorcube (Games)
Colorcube 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Turn pieces and blend colours in this minimal yet visually stunning puzzler.Over 200 handcrafted and challenging levels. Features... | Read more »
Doodle God Griddlers (Games)
Doodle God Griddlers 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: | Read more »
Crusader Kings: Chronicles (Games)
Crusader Kings: Chronicles 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: Crusader Kings: Chronicles is an interactive text based game that puts you in the shoes of Guy de Rose as you make... | Read more »
Roads of Rome: New Generation (Games)
Roads of Rome: New Generation 1.0 Device: iOS Universal Category: Games Price: $5.99, Version: 1.0 (iTunes) Description: | Read more »

Price Scanner via MacPrices.net

Charitybuzz Set to Auction Unique Apple-1 Com...
Offering an opportunity to own the computer that sparked a revolution, on Monday, July 25, leading online charity auction platform Charitybuzz will auction what is claimed to be the world’s most... Read more
MacBook Airs on sale for up to $150 off MSRP
Amazon has 11″ and 13″ MacBook Airs on sale for up to $150 off MSRP for a limited time. Shipping is free: - 13″ 1.6GHz/128GB MacBook Air (sku MMGF2LL/A): $899.99 $100 off MSRP - 13″ 1.6GHz/256GB... Read more
Apple refurbished 13-inch Retina MacBook Pros...
Apple has Certified Refurbished 13″ Retina MacBook Pros available for up to $270 off the cost of new models. An Apple one-year warranty is included with each model, and shipping is free: - 13″ 2.7GHz... Read more
Apple refurbished 11-inch MacBook Airs availa...
Apple has Certified Refurbished 11″ MacBook Airs (the latest models), available for up to $170 off the cost of new models. An Apple one-year warranty is included with each MacBook, and shipping is... Read more
Apple iPad Pro Sales Far Outpacing Microsoft...
A report on Appleinsider notes that despite Microsoft Surface tablet PC sales growing by 9 percent year over year, revenues remained below $1 billion, and are down sequentially from the $1.1 billion... Read more
DEVONthink 2.9 Features Ultra-fast, Robust, A...
DEVONthink 2.9 allows users to keep databases synchronized using many means of transport. It transmits them between Macs on the local network or stores them in a syncable form on removable hard... Read more
12-inch WiFi Apple iPad Pros on sale for up t...
B&H Photo has 12″ WiFi iPad Pros on sale for up to $100 off MSRP, each including free shipping. B&H charges sales tax in NY only: - 12″ Space Gray 32GB WiFi iPad Pro: $749 $50 off MSRP - 12″... Read more
Apple refurbished 15-inch Retina MacBook Pros...
Apple has Certified Refurbished 2015 15″ Retina MacBook Pros available for up to $380 off the cost of new models. An Apple one-year warranty is included with each model, and shipping is free: - 15″ 2... Read more
Apple refurbished Mac minis available for up...
Apple has Certified Refurbished Mac minis available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: - 1.4GHz Mac mini: $419 $80 off MSRP - 2.6GHz Mac... Read more
Apple Mac Sales Finally Colliding With ‘Innov...
After successfully swimming against a tide of diminishing PC sales through 2014 and 2015, it appears that Apple has finally stopped defying gravity and is running up against the unwritten “innovate... Read more

Jobs Board

*Apple* Solutions Consultant - APPLE (United...
Job Summary As an Apple Solutions Consultant, you'll be the link between our future customers and our products. You'll showcase your entrepreneurial spirit as you Read more
*Apple* Professional Learning Specialist - A...
Job Summary The Apple Professional Learning Specialist is a full-time position for one year with Apple in the Phoenix, AZ area. This position requires a high Read more
*Apple* Picker - Apple Hill Orchard (United...
Apple Hill Orchard, Co. Rte. 21,Whitehall, NY 9/7/16-10/228/16. Pick fresh market or processing apples Productivity of 60 boxes and 80 boxes processing fruit per Read more
*Apple* Solutions Consultant - APPLE (United...
Job Summary As an Apple Solutions Consultant, you'll be the link between our future customers and our products. You'll showcase your entrepreneurial spirit as you Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description:SalesSpecialist - Retail Customer Service and SalesTransform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.