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PICT to RMaker
Volume Number:3
Issue Number:5
Column Tag:Toolbox Techniques

PICT to RMaker Source in MacForth

ArticleSubhead

By Larry Tannenbaum, Long Beach, CA

This program illustrates calling traps, using dialog boxes, the desk scrap, and the memory manager from MacFORTH. It takes a picture from the clipboard and converts it to RMaker resource format. The converted picture is put back into the desk scrap, so you can paste it into your resource file, using MockWrite or other editor.

Dialog boxes make programs more Mac-like and more "attractive", but they can be a bit tricky in MacFORTH. The reason is that the MacFORTH window always executes an ABORT when it is activated, and it is always activated when the dialog box is erased, if it was active before the dialog was drawn (To see what else is done when the MacFORTH window is activated, try SYS.WINDOW +ON.ACTIVATE W@. Use the forth decompiler from MacTutor Vol 1,#2 to decompile this token). For example, you start your program that calls a modal dialog box by typing the highest-level word in the MacFORTH window. When the dialog box is drawn in front, the MacFORTH window is de-activated. When the dialog is disposed of, the MacFORTH window is automatically activated and your program is aborted. This program works because all processing is done, before the dialog box is disposed of.

A couple of words in the program are from Thinking Forth:

: \  >IN @ 3C0 AND C/L + >IN ! ;  IMMEDIATE  (skips rest of line)
: ASCII  BL WORD 1+ C@ COMPILING IF [COMPILE] LITERAL THEN ;

IMMEDIATE  (leaves ascii value of following character on stack, or compiles 
it as a literal if used within a definition)

I also used one naming convention from Thinking Forth. Word names starting with "/" imply "bytes per", so /Row means bytes per row. I also tried to use descriptive names and ample comments. Forth can be hard to decipher, but doesn't have to be.

MacFORTH provides several pre-defined words for defining your own trap-calling words. What they do is compile machine code into your definitions that formats the stack for you, such as converting items that are supposed to be integers from the 32 bits that MacFORTH uses for everything, to 16 bits, or taking all of the arguments off the stack, reserving space for a returned result, then putting the arguments back on the stack. They also compile the trap code into the word.

Fig. 1 Pict to RMaker source Dialog Box

These pre-defined words are listed in table 1 along with the argument patterns they work for. Since the "FUNC" words must reserve space on the stack for a returned value underneath the arguments, they are for very specific cases only; the "MT" words are more general. For example, W>MT may be used with a trap that needs one 16-bit item on top of any number of 32-bit items, but W>FUNC>L must be used with a trap that takes one 16-bit argument only. If the trap you want to use doesn't fit any of these patterns, you must format the stack yourself and use MT for your definition.

Blocks 1 to 4 contain examples of calling traps from MacFORTH. The word WAdj, in Block 1, converts 32-bit items to 16 bits; it adds 2 to the stack pointer, essentially chopping off the two most significant bytes of the top stack item. I couldn't get OPEN.RSRC, supplied by MacFORTH 1.2 K2.3, to work, so I defined my own word, OpenRFile, to do the job. The 2nd line of code in block 2 is executed while the file is loading. It takes the name of the loading file as the resource file name. This way, if you rename the file, the resource fork will be opened properly without changing the code.

How do you get resources into a block's file? First, compile the resources with RMaker. The type and creator of the output file should be BLKS M4TH. Go to MacFORTH and open the new resource file with OPEN" rfilename". You have just opened the empty data fork of the file. Append enough blocks to it to hold the program (APPEND.BLOCKS). Either type in the program, or use XFER.BLOCKS (block 12 of Forth Blocks) to transfer it from another block's file. It's easier to use separate resource and blocks files, when developing a program. Finally, change the name of your completed file, because RMaker will delete it, if you recompile the resources.

I decided to use the desk scrap for the input and output of this program so that I could paste the picture resource into the middle of an existing file. It's also easy to select a portion of a picture with Paint Grabber or similar desk accessory and retrieve it from the desk scrap using GET.SCRAP.

Table 1: MacForth trap calling defining words

GET.SCRAP copies the scrap data to a handle that you pass to it. The handle is automatically sized, so it can be any length, including zero. You must also specify the type of data you are looking for. The most common types are text and pictures. Use the constant "TEXT or "PICT to designate the type you want. If the data in the scrap is different from the type you asked for, error code -102 is returned. An error code of zero indicates no error.

PUT.SCRAP works similarly. Give it the address and length of the data, and the data type. It will copy your data to the end of the desk scrap and return a result code.

ZERO.SCRAP deletes all data in the desk scrap and sets the scrap length to zero. You must execute ZERO.SCRAP before the first time you execute PUT.SCRAP, and before putting data into the scrap of the same type that is already there. This last restriction is necessary because GET.SCRAP always returns the first block of data of the type requested. If more than one chunk of data of a particular type is in the scrap, only the first one that was written is accessible.

Two other words help conserve memory: LOAD.SCRAP and UNLOAD.SCRAP. UNLOAD.SCRAP writes the desk scrap to the clipboard file on disk, releasing the memory used by the scrap. LOAD.SCRAP "knows" whether the scrap data is on disk or not and reads it into memory, if necessary. GET.SCRAP apparently will not get the data from the disk, even though Inside Macintosh says it will, so call LOAD.SCRAP first, if there is the possibility of it being in the clipboard file.

SCRAP.HANDLE returns the address where the handle to the desk scrap is stored. SCRAP.COUNTER returns the number of times the scrap has been zeroed since system start-up. According to Inside Macintosh, you can check to see if this value has changed during the operation of a desk accessory. If so, the accessory has probably put some data into the scrap.

SCRAP.LEN returns the address containing the length of the scrap data. This length includes 8 bytes for the scrap header. Sometimes the scrap is 8 bytes longer than the picture length, and sometimes it is 9 bytes longer. I suspect this has to do with whether the picture size is odd or even. The program needs the length of the picture. The easiest way to get it is from the first two bytes of the picture itself, so I don't use SCRAP.LEN. Block 8 contains the definitions using the scrap interface words.

Block 5 holds the memory manager interface definitions. Many programs in MacTutor have dealt with getting, releasing, resizing, locking, and unlocking handles, so I won't go into detail. The MacFORTH words that do these things have explicit names, except maybe FROM.HEAP, which gets a handle, and TO.HEAP, which releases one.

The program uses only one handle. GET.SCRAP copies the picture into it, then the handle is resized to hold the ascii. To avoid overwriting the data, the program starts converting from the end of the picture.

Blocks 9 and 10 contain the code that actually does the conversion. The constant /Row, in block 9, determines how many bytes of the picture are represented on each row of text. It can be changed to any convenient value.

Using this program, you can personalize your dialog and alert boxes, and keep the pictures in your source, rather than having to paste them in after compilation with ResEdit. The output format could also be changed to MDS or MacASM.

( Block 0    ***********Instructions*********** )

To use this program:
    1.  Cut or copy picture to be used as resource so it will
        be in the ClipBoard.
    2.  Load this file.
    3.  Execute Pict>Rsrc. The PICT in the clipboard
        will be converted to type TEXT in RMaker hex format.
    4.  Using MockWrite or other editor, paste the data from
        the clipboard into the RMaker file.

( Block #1   ***********Toolbox interface***********)

HEX

Create WAdj -2 Allot 548F { ADDQ.L #2,SP} W, 4ED4 W,

A997 L>FUNC>W <OpenRFile>        A99A W>MT <CloseRFile>
A97C MT <GetNewDlog>             A983 MT <DisposDlog>
A98D MT <GetDItem>               A991 MT <ModalDlog>
A990 MT <GetIText>               A98F MT <SetIText>
A95F MT <SetCTitle>              A95D W>MT <HiliteControl>
A987 MT <NoteAlert>

DECIMAL
    2 11 Thru

( Block #2   ******ToolBox InterfaceVariables*********)

Create   RFileName    30 Allot \ same name as this file
Block-File @ @File.Name    Dup C@ 1+ RFileName Swap CMove
Variable RFileRefNum           \ returned by OpenRFile
Variable DlogPtr               \ returned by GetNewDlog
Create   ItemHit 2 Allot       \ returned by ModalDlog
Create   ItemType 2 Allot      \ returned by GetDItem
Variable ItemHandle            \ returned by GetDItem
Create   ItemRect 8 Allot      \ returned by GetDItem
Create   Item$ 30 Allot        \ for manipulating text items
Create   Ok$ ," Done"          \ new title for control
1 Constant ConvertButton       \ compared to ItemHit when
                               \ ModalDlog returns

( Block #3    ***********Resource File/Alert***********)

: OpenRFile    RFileName <OpenRFile> Dup 0>
    If   RFileRefNum !
    Else Abort" Couldn't open resource file!" Then ;
: CloseRFile   RFileRefNum @ <CloseRFile> ;
: NoPictAlert  128 WAdj ( id) 0 ( filter proc) <NoteAlert> ;

( Block #4    ***********Dialog Interface***********)

: GetDlog    0 ( reserve stack space for returned dptr)
    128 WAdj ( id) 0 ( on heap) -1 ( in front)
    <GetNewDlog>    DlogPtr ! ;
: DisposeDlog  DlogPtr @ <DisposDlog> ;
: ModalDlog    0 ( filter proc) ItemHit <ModalDlog> ;
: GetDItem    ( item#)    DlogPtr @ Swap WAdj
    ItemType  ItemHandle ItemRect <GetDItem> ;
: GetIHandle  ( item#--handle)    GetDItem ItemHandle @ ;
: GetIText    ( $\item#)    GetIHandle Swap <GetIText> ;
: SetIText    ( item#)    GetIHandle Item$ <SetIText> ;
: Ok>Done  1  ( item#) GetIHandle Ok$ <SetCTitle> ;
: Can'tCancel 2 ( item#) GetIHandle 255 <HiliteControl> ;

( Block #5    ***********Memory Manager***********)

Variable DataH    \ holds handle to data

: GetH ( size--handle)    From.Heap Dup DataH ! Dup 0=
    If DisposeDlog CloseRFile
        1 Abort" Handle Allocation Error!" Then ;
: DataPtr ( --ad of data)    DataH @@ Mask.Handle ;
: /Data ( --data size in bytes)    DataH @ Handle.Size ;
: ResizeH ( new size--)    DataH @ Dup Rot Resize.Handle
        0< If   DisposeDlog CloseRFile
            1 Abort" Handle Resize Error!"
        Else Lock.Handle Then ;
: ReleaseH
   /Data 0< Not If DataH @ Dup Unlock.Handle To.Heap Then ;

( Block #6    ***********PICT Resource Header***********)

13 Constant CRet    \ ascii for carriage return
: AddCR ( ad--)     Count 1- +    CRet Swap C! ;
\ Asterisk in string is place holder for carriage return
Create Type$ ," TYPE PICT = GNRL*"  Type$ AddCR
Create Hex$  ," .H*"                Hex$  AddCR
Create Name$ 25 Allot
Create ID#$  10 Allot
: /Header ( --n)    Type$ C@ Hex$ C@ Name$ C@ ID#$ C@ + + + ;
: (Header>Text) ( ptr\$--updated ptr)
    Count >R Over R@ CMove R> + ;
: !Header    DataPtr            Type$ (Header>Text)
             Name$ (Header>Text) Id#$  (Header>Text)
             Hex$  (Header>Text) Drop ;

( Block #7    ***********Get/Set Dialog Items***********)

: Num>Str ( n)       <# #S #> Item$ 2Dup C!    1+ Swap Cmove ;
: AddChar ( $\char)  Over Count + C!    Dup C@ 1+ Swap C! ;
: SetPictSize        DataPtr W@ Num>Str 9 SetIText ;
: SetPictWidth
    DataPtr Dup 8+ W@ Swap 4+ W@ - Num>Str 11 SetIText ;
: SetPictHeight
    DataPtr Dup 6+ W@ Swap 2+ W@ - Num>Str 13 SetIText ;
: GetPictName    Name$ Dup 5 GetIText Ascii , AddChar ;
: GetPictID#     ID#$ Dup 7 GetIText CRet AddChar ;
: GetHeader      GetPictName    GetPictID# ;
: SetUpDlog
    GetDlog SetPictSize SetPictWidth SetPictHeight ModalDlog ;
: DoneDlog       Ok>Done Can'tCancel ModalDlog ;

( Block #8    ***********Desk Scrap Interface***********)

: ScrapErr? ( result code--)
    0< IF ReleaseH DisposeDlog CloseRfile
          1 Abort" Scrap Error!" Then ;
: /Pict ( --bytes)
    Scrap.Handle @ Dup 0< If Drop 0 Else @ 4+ @ Then ;
: PictFromScrap ( --result code)   Load.Scrap ScrapErr?
    /Pict GetH    "PICT Get.Scrap ;
: Text>Scrap    Zero.Scrap ScrapErr?
    DataPtr /Data "TEXT Put.Scrap ScrapErr?
    ReleaseH    Unload.Scrap ScrapErr? ;

( Block #9    ***********Picture conversion***********)

16 Constant /Row   \ 1 row of text represents 16 bytes of pict
: #CR'S ( pict size--# of CR's in text )
    /Row W/Mod Swap If 1+ Then ;
: /Text ( --text size) /Pict Dup 2* Swap #CR'S + /Header + ;
: PictEnd ( --ad)    DataPtr /Pict + 1- ;
: TextEnd ( --ad)    DataPtr /Text + 1- ;
    Create Char$ ," 123456789ABCDEF"    Ascii 0 Char$ C!
:  >Ascii ( nybble--char)    Char$ + C@ ;
: !Byte  ( ad\byte--new ad)    Dup>R 15 And >Ascii Over C! 1-
                               R> 16/    >Ascii Over C! 1- ;
: !Cr    ( ad--new ad)    CRet Over C! 1- ;

( Block #10   ***********Picture conversion***********)

Variable PictAd

: RowLimits ( #bytes--limit\index)
    PictAd @ Dup Rot - Dup PictAd ! 1+ Swap ;
: !Row    ( dest ad\#bytes--new dest ad)
    RowLimits Do IC@ !Byte -1 +Loop ;
: !Pict    PictEnd PictAd !    TextEnd
    1 /Pict Do !Cr   I /Row Min !Row  /Row Negate +Loop Drop ;
: Pict>Text    Watch Set.Cursor  GetHeader
        /Text ResizeH    !Pict !Header   Init.Cursor ;

( Block #11    ***********User Interface***********)

: Convert?    ItemHit W@ ConvertButton = If
    Pict>Text Text>Scrap DoneDlog Then ;
: ConvertPict    SetUpDlog Convert? DisposeDlog ;
: Pict>Rsrc      OpenRFile PictFromScrap
    0< If   NoPictAlert
       Else ConvertPict
       Then CloseRFile ;
 

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