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WINDOID Issue #5

A Publication for the Informed HyperCard User
and the Newsletter for the  Apple HyperCard User Group

Editor -- David Leffler

In the fifth issue of WINDOID, Sioux Lacy gives you important information about
HyperCard external commands (XCMD's) and external functions (XFCN's) .  These
are the "Magic Hooks" that can written in "C", Pascal, or 68000 assembly
language , and used to create exciting extensions to HyperCard functionality.
Additionally, Phil Wyman has given us more HyperCard User Tips, Robin Shank
explains some HyperCard features, James Redfern gives us an explanation of some
HyperTalk concepts, and Paul Foraker teaches us how to Show hidden buttons and
fields and how to Set scripts of objects on the fly.

I have had many requests for issues of WINDOID.  If you would like a copy, or
copies, please send a Self Addressed Stamped Envelope (SASE) to the address
listed on THE FORM for each issue.
Thank you  for your continued interest in WINDOID.
==========

Editors Choice
By David Leffler

Color, a XCMD written by Bill Tuttle is an incredible voyage into the world of
color HyperCard!  This stack will only be truly appreciated by Macintosh II
users with at least 16 colors but it is a delicious taste of what can be done
with XCMDs.
==========

About XCMDs and XFCNs....
by Sioux Lacy
Tips & Techniques for Users of External Code Resources

Many of you may not be aware of yet another tool HyperCard has provided for the
stack designer/user.  External commands or functions can be used to create an
extension to HyperCard functionality.   Accessed much in the same manner that
user-defined commands and functions are, "XCMD"s and "XFCN"s are code resources
that can be attached to any stack.

Several external commands are included with the HyperCard product:
"Flash" is an XCMD that will flash the screen (invert black and white, then
invert back again).  Its attached to the HyperCard application so it can be
accessed from any stack with the command "Flash", followed by the number of
times you would like the screen to flash.

If you look in the Documents Representative stack, you will find another
example of an external command:  "Getdocs".  It is called by the "Update"
button's script.  A line in the "mouseUp" handler reads:

          getdocs line i of documents

This is a call to the "getdocs" command, passing it one argument which is a
folder name from the Documents card in your Home stack.  "Getdocs" responds by
creating the cards in the Documents stack.

Already some interesting external commands have appeared as shareware.  Some of
them provide the user with a button that will attach the external code to your
stack, but if you discover one that hasn't, you can use the following method to
do so:

To attach an existing external command to one of your stacks, you will need to
use a resource mover, like ResEdit, to copy it from its current stack, and
paste it into your stack.  In ResEdit, this procedure works as follows:
1) Launch ResEdit
2) Find the stack with the external command or function that you want to copy,
and open that stack
3) You will see a resource type of XCMD (or XFCN)
4) Select and copy the resource
5) Then find and open your stack
6) It will probably ask you if you want to open a "resource fork" for your
stack (unless it already has one).
7) Click "Ok", ResEdit will open a window into which you can paste the
resource.

About XCMDs....
Tips & Techniques for Writers of External Code Resources

For you Pascal, C, or 68000 assembly language programmers who want to write
your own external commands, here are a couple hints:

1  Most importantly, do get the "HyperCard Developer's Toolkit" package from
APDA, Apple Programmer's & Developer's Association is located at:
   290 SW 43rd Street
   Renton, WA 98055
This package includes a disk, called "Magic Hooks", with sample source files in
Pascal and C, and preliminary documentation.

2  Don't declare any global or static variables.  Externals cannot share
HyperCard's global data space.  You can allocate space on the heap with
"NewHandle" or "NewPtr" calls, but be sure to dispose of that space before you
return to HyperCard.

3  Some of the callback glue routines also return handles to the caller.
(specifically, PasToZero, EvalExpr, GetGlobal, GetFieldByName, GetFieldByNum,
and GetFieldByID)  In these cases, HyperCard has allocated the space associated
with these handles, and your code is responsible for deallocating it once
you've examined its contents.

4  The rule about disposing handles and pointers that your code allocates has
one exception:  if you allocate space in order to return a string to HyperCard
in the "returnValue" element of the XCmd parameter block.  HyperCard has not
pre-allocated any heapspace for that handle.  You must do the allocation in
your code, then copy your return message into that allocated space.  HyperCard
will dispose of the space for you.

An example that combines usage of a callback routine, and assignment to a
returnValue follows.  Note that in this case, you do not deallocate the handle.
This example uses the "PasToZero" callback routine to copy a string and
zero-terminate it for return to HyperCard.

paramPtr^.returnValue :=  PasToZero('An error has occurred.');

5  For testing externals, one useful technique is to call your code repeatedly
from Hyper-Card, and "put the heapspace" in between the calls.  If you see a
rapidly diminishing heap, you might suspect that your external is allocating
space and forgetting to dispose of it.

6  An error in the "Magic Hooks" documentation: the callback routines,
"ExtToStr" and "StrToExt" convert floating point numbers to strings and vise
versa -- not to convert extended long integers.  Oops, sorry about the error.

7  HyperCard stores strings as zero-terminated arrays of any length.  This is
consistent with the way 'C' handles strings, but not Pascal.  So, for example,
when a Pascal code resource receives parameters, it will need to convert the
strings to Pascal strings (beginning with a length byte, and no
zero-terminator).  Read the documentation for the callback glue routines
carefully.  Some of those routines return zero-terminated strings, and others
return Pascal strings.  Your code will need to convert if appropriate.

Also, remember that a Pascal string is limited in length to 255 characters.
So, for example, if you have a zero-terminated string that is longer than that,
and you call ZeroToPas to convert it for you, HyperCard will truncate your
string to 255 characters.

8  If you're writing external code in MPW 'C', there are some additional
constraints that you need to be aware of regarding string literals.  In an
environment that has global and static data initialization, you can copy a
string to the space referenced by a handle in this manner:

myHndl = NewHandle( STRINGSIZE );
strcpy( *myHndl, "Hello world" );     /* probably should lock this handle */
                                    /* and unlock it after the strcpy call */

In an MPW C (see Lightspeed note below) external code resource, you cannot use
a string literal.  Instead you must create an STR# resource that contains your
strings (use ResEdit to do this), and then retrieve them with a call to
GetIndString:

char myString[ STRINGSIZE ];           /* make an array large enough */

GetIndString( myString, RESOURCE_ID,  STRING_NUM );

9  It is not necessary to initialize the various Tool Managers in your external
code.  HyperCard has already done this, and in some cases, such as the
GrafPort, reinitialization can be hazardous.

Note:  LightSpeed C will allow the string literal to be passed as an argument.
==========

HyperCard User Tips
by Phil Wyman

1.  There is a form of the Repeat command which works with "down to". "Down to"
is two words in this syntax. This form of the repeat command will iterate your
variable downward each step through the loop.

   repeat with x = 100 down to 1
     put x into field 1
     go next card
   end repeat

An example of a useful application of the "repeat down to" command is if you're
deleting all the buttons or deleting all the fields of a card or background.
For instance,

   put the number of buttons of this card into var
   repeat with x = var down to 1
     choose button tool
     click at the loc of button x
     doMenu "Cut Button"
   end repeat

If you had done this with "x = 1 to var" instead of "x = var down to 1" then
soon you would be clicking at a button that didn't exist.

2.  There's a nice debugging feature in the HomeStack Script. The handler is
called searchscript, and its two parameters are first the string you are
searching for, and second the stack that you are going to be searching for that
string.  What if, for example, you had hundreds of cards with scripts, and you
found you misspelled a word in one script. You could then search all your
scripts to find which ones had the same misspelling error. You would say in the
message box:

   searchscript "mispelled word","stackname"

3.  You do not have to have your cursor at the end of your message in the
message window in order to execute your message.  In the message window, you
may be typing along on the fifth word and found that you've made a typing error
on the first word.  You click on the first word and correct your error.  Now
the cursor is in the first word. At this point you can still hit the return or
enter keys to execute the message window, even though your cursor is not at the
end of the message.

4.  An easy way to copy a current background in your stack into a new
background in the same stack is:

Copy card, go to a temporary stack, paste Card. Immediately copy card, go to
original stack and paste the card.  This should create a new background in your
stack that is exactly like your old one.

If you need to copy the foreground of a card to the current background, try the
free utility stack "Foregnd to Bkgnd".
==========

"It's a Feature"
Explanations of some HyperCard features
by Robin Shank

Drawing through scripts:
Because  the Polygon tool is controlled differently than the other drawing
tools, the Drag From command won't work in this tool.  If you need to plot
irregular shapes, use the Curve tool, or the Line tool instead.  The Lasso
tool depends on an enclosing movement to select something, but a script will
only drag in a straight line.

In many cases when you draw through a script, you will want to set the
dragSpeed down to around 500.  With the dragSpeed at the default setting, the
Spray tool will only show the starting and ending points, because the spray
cycle is slower than the movement on the screen.  Also, with Draw Multiple on,
you won't see any multiples unless the dragSpeed is slowed down.

Printing Notes:
Background fields that are overlapped by another object or card picture will
print at 72 dpi on the LaserWriter.  A piece of card paint whose rect overlaps
a background field will cause that background field to print at 72 dpi.  (The
rect can be shown by the rectangle formed by the marching ants when drawn by
the selection rectangle.)  One exception:  if a transparent button that
does not show a name or icon covers a background field, that field will still
print at high resolution.

After printing a stack or report,  the format is saved as the default.
However, when printing cards through a script using Open printing with dialog,
the dialog will show the default format determined by the last Print Stack, but
changes to the printing format are not saved and affect only that one print
job.

MultiFinder...
750K is the absolute minimum memory configuration recommended to run HyperCard
under MultiFinder.  If you run HC under MultiFinder on a 1 Mb machine, you will
be limited to Typing UserLevel and processes that need more memory (such as
pasting graphics or printing) will, at the least complain, and at the worst,
exit grumpily back to the Finder.  (who said crash??)

When printing under MultiFinder with Background Printing ON, Print stack sends
copious amounts of data to the LaserWriter in a very short period of time.  If
a spooler of any kind is catching that before sending it to the printer, it is
likely to fill up very quickly.  A MultiFinder Spool folder for a 10 card, 20K
stack could easily be over 1 Mb.  (500K + per card is being sent to the
LaserWriter)
==========

Some Things Useful
by James Redfern

This is a short explanation of some concepts that are useful in using
HyperTalk:

 A container is what you put your information into.  Containers are: "it",
"selection", the message box, a field, or a variable.  Containers can be
thought of as open or closed.  An open container displays information on the
screen; the contents of a closed container can not be viewed.  Variables and
"it" are closed containers.  The number of characters in an open container must
be less than 32K, probably less than 30K to be safe, and less than 5K if a
scrolling field is to respond quickly.  The number of characters in a closed
container are limited by available memory.  (An exception is the use of the
prepositions "before" or "after" with a closed container, which limits the
number of characters to 64K.)

 Information is represented as a string of characters.  Strings can sometimes
be further interpreted as numbers or the logical values: "true" and "false".  A
number can be further interpreted as an integer or unsigned integer.

 When HyperCard performs an operation that requires numbers as operators, such
as addition, it will try to interpret, i.e. convert, the strings as numbers.
If the resulting number is put into a closed container, the container will
retain the full precision of the internal representation.  If the resulting
number is put into an open container, the number must be represented, i.e.
converted, as a string.  HyperTalk uses the current value of the numberFormat
property to format the string representation.

 When HyperCard performs an operation that requires strings as operators, such
as concatenation, it will first represent any numbers as strings using
numberFormat.  The resulting string will remain a string even if it is put into
a closed container.

 Constants, such as "pi" or "zero", represent strings of digits, and are not
interpreted as numbers unless forced to by an operation.  Therefore, "put pi"
results in "3.141592653..." but "put pi + 0" results in "3.141593" (the "+"
forced "pi" to be converted to a number, which had to be converted back to a
string since the message box is an open container, so numberFormat was used to
round to six fractional decimal places).

 Comparison is an operation that will try to interpret strings as numbers.
Therefore, "3" > "20" is false, but "*3" > "*20" is true:  If the goal is a
string comparison and the values could be interpreted as numbers, then a
non-numeric character must be concatenated to both values, such as 'if "*" &
variable1 > "*" & variable2 then...' to prevent interpretation as a number.
Remember that equality comparisons, "=" and "<>", use only primary ordering of
characters, so case and diacriticals are ignored.  Magnitude comparisons use
both primary and secondary ordering.
==========

Showing and Setting
by Paul Foraker

--Please remember that a  is an Option-Return in ASCII TEXT
--format.   Editor

Lost and Found

In the process of designing your own stacks, once in a while youre likely to
forget things. If youve ever hidden a field or a button from yourself, you
might appreciate this little script.

-- make a new button anywhere on your card
-- (youll delete it later) & put this script in it:
on mouseUp
  repeat with i = 1 to the number of fields
    -- or bkgnd buttons, or card fields, or buttons
  show field i
    -- or bkgnd button i, etc.
  end repeat
end mouseUp

Now, when you click on this temporary button, all your hidden fields or buttons
will come into view.

Setting Scripts of Objects on the Fly

There are times when you want a HyperTalk script to make new objects (like
buttons or fields) and put scripts into them. The command for getting scripts
into objects is set script of <object> to <source>.  This command can be used
in a number of different ways. Lets look at some examples (for the sake of
simplicity, Ive assumed that were using a simple button mouseUp handler to
set the script of a button named, target.):

-- getting the new script directly from the executing handler
-- (remember not to use Option-Return inside a quoted string)
on mouseUp
  set script of button "target" to "on mouseUp" &
  return & "go next card" & return & "end mouseUp" & return
end mouseUp

--getting the new script from a field
on mouseUp
  set script of button "target" to field 1
end mouseUp

--getting the new script from another object
on mouseUp
  set script of button "target" to script of button 2
end mouseUp

--modifying an existing script
--lets say we think the old script was simply (on mouseUp) "go next
--card", but we're not sure; it might already have a visual effect,
--and we want to add a visual effect:
on mouseUp
    --first check for a visual effect & get out if there is one
  if script of button "target" contains "visual" then exit mouseUp
    -- if not, then modify the script
  put script of button "target" into temp
  put return & "visual effect wipe left" after line 1 of temp
  set script of button "target" to temp
end mouseUp

[Thanks to Linda Donovan for the suggestions.]
==========

Wanted:
StackWare Reviews and Recommendations for Whole Earth Catalog
by Tim Oren


The Whole Earth Catalog rides again!  Apple and the Point Foundation have
collaborated on a HyperCard version of the Whole Earth Catalog which was shown
at MacWorld and gained significant media  attention.  Now we are beginning
phase two of this project, which will incorporate reviews and recommendations
of StackWare and HyperCard tools and accessories.  Because of the rapid
proliferation of stacks, we must rely on you, the users, to bring significant
developments to our attention.  Particularly, we are looking for
recommendations or short reviews of:

 HyperCard Tools:  These can take the form of stacks incorporating significant
extensions to HyperCard, in the form of scripts or XCMDs.  Examples might be
online service frontends, techniques for scrolling links, resource moving and
conversion utilities, generalized text import or export techniques.  Non-stack
tools might include: useful DAs or companion programs to assist in building
stacks, data import devices (scanners, digitizers, ...) which help convert
material into stack format, and books, magazines, and teaching aids which help
in learning or using HyperCard.

 Stacks with significant content:  HyperCard was designed as a information
vehicle for the non-programmer.  Many significant stacks may not show a lot of
programming "flash" but will contain vital data.  For example, star catalogs,
pharmaceutical directories, industry guides, and so on.  Let us know what's out
there.

 Stackware as a new media artform:  We are beginning to see stacks that use
HyperCard as a fusion artform, collaging graphics, sound, stored dynamics, and
browsing into an interactive experience.  We are interested in stacks leading
in this direction of "information as art".

 Things we've missed:  This area is moving so fast that we have undoubtedly
overlooked major categories and themes.  Please bring them to our attention.

Keep in mind that we are in the early days of stackware development.  The items
we include should have "staying power" - they should be of such a quality that
they will still be of interest in a year, let's say.  We encourage electronic
submission of reviews - please include the stack or tool itself if it is
freeware or shareware, otherwise please give us the full reference to the
publisher so that we may verify pricing and availability information.

All submissions will be considered, though not all will be used.  Submissions
used will earn you a byline in the first-ever electronic Whole Earth Catalog
and the knowledge that you have done a Good Deed for the HyperCard user
community.  Submissions may also be considered for inclusion in the Whole Earth
Review magazine, which carries a monetary reward as well.

Here are our addresses:

Uucp:  ucbvax!well!hank
Compuserve:  leave message in WEC sig
AppleLink:  OREN1
SnailMail:
  Whole Earth Stackware Toolbox
  27 Gate Five Rd.
  Sausalito, CA  94965
==========

We hope you have enjoyed reading WINDOID and have found it to be interesting
and informative. We care enough to take the time to give you the most
up-to-date information about HyperCard, and we would like to make a request for
a little of your time. There is a form that follows this editorial; please fill
it out if you will. We are very interested in hearing from you. What sort of
stacks are you using, what kind of stacks are you creating, and what are your
joys and frustrations in using HyperCard.

You have the unique opportunity to communicate directly with Bill, Dan, and the
entire HyperCard development team. We really want to know what you would like
to see in HyperCard and are more than willing to give you what you want. What
we need to make this happen is your input. Let us know what you think. We can
address it in WINDOID or perhaps the next revision of HyperCard. You can make a
difference in the world by communicating with us. Dont pass up the
opportunity!
==========

If you have a bug, suggestion, comment, or just want to know
the best way to do something in HyperCard, you can fill out the form and send
it to:

AHUG c/o David Leffler
Apple Computer, Inc.
MS/27-AQ
20525 Mariani Ave.
Cupertino, CA 95014

Or copy the format and
Apple-Link it to:
HYPERBUG$

TELL HYPERCARD
You can use this form to notify the HyperCard team of problems, bugs, and
enhancement requests.

THE FORM:

Please use the following form to make a difference in the world:

Date:
Name:
Address:
Phone #:
Versions of:
 a.  HyperCard:
 b.  Associated software:
 c.  System Software:
     1. System
     2. Finder
     3. ImageWriter file
     4. LaserWriter file
     5. Any others
Type of Macintosh:
Peripherals:
Description of problem, suggestions or comments:


Please fill this form out as completely as possible and send it to us.  You
will be glad you did!




--

Apple's HyperCard Grievance Center
"Give us your bugs, your comments, your gentle criticisms..."

UUCP:  {pyramid!sun,voder,nsc,ucbvax!mtxinu,dual,decwrl,amdahl}!apple!hyperbug