MacGS-510
 
A port of Aladdin Ghostscript to the Macintosh

Version 503 ‹ Oct 18th, 1997

Version 510 ‹ Dec 1st, 1997

Ghostscript by L. Peter Deutsch
MacGS  & Macintosh drivers by Jeff Schindall

Copyright © 1988-1995, 1997 Aladdin Enterprises,
Menlo Park, CA.  All rights reserved.
Very Quick Introduction to Ghostscript

Ghostscript is a PostScript interpreter.  PostScript is a language, not a 
graphic file format.  A PostScript file is really a program, not graphical 
data.  The difference is that by looking at a PostScript file you (or an 
application) cannot easily tell what the file represents.  Instead, you 
must run the file to see what it does.  Generally, the result of running a 
PostScript program is to draw marks on a graphical page.  (There are 
PostScript programs that don't draw anything at all!  Some are even 
distributed as test files with Ghostscript.)  This works well for printers 
but is a bit odd for interactive window systems.

Think of MacGS as a virtual printer: Every time you open a file, asking 
Ghostscript to run it as a PostScript program, the application creates a 
new sheet of 'paper' and displays it in a window.  You can see the program 
execute as it places marks on the 'paper' in the window (unless your 
computer is much faster than mine!)  Once the program is done, the page is 
'ejected' from the printer.  However, the application leaves the window on 
the screen so you can continue to look at it (and scroll it, save it, 
etc.).  But remember, at this point, the page is out of the printer and 
Ghostscript can no longer change it.  If you want to change some parameter 
(such as scaling), you must change the parameter and then re-open, and thus 
re-run, the PostScript file.

Please see the file readme and the files that end in .txt in the doc 
folder for more information.

Unpacking

The release consists of the following files:

  macgs-510-files.sit  ‹ Ghostscript files and documentation
  macgs-510-68k.sit    ‹ the application compiled for 68020 or better
  macgs-510-ppc.sit    ‹ the application compiled for PPC machines
  macgs-510-fat.sit     ‹ the application compiled for both 68k and PPC machines
  macgs-510-fonts.sit  ‹ the standard Ghostscript 5.xx fonts
  macgs-510-src.sit    ‹ the source files

These files are StuffIt archives.  If you do not have a program to expand 
these, you should get the free StuffIt Expander program from your favorite 
Macintosh archive.

For users who have limited memory, the following executables are provided:

  macgs-lite-510-68k.sit    ‹ the application compiled for 68020 or better
  macgs-lite-510-ppc.sit    ‹ the application compiled for PPC machines
  macgs-lite-510-fat.sit     ‹ the application compiled for both 68k and PPC machines

The "Lite" version of MacGS contains only the macintosh rendering device, 
and the pdfwriter device.

[ 1 ] Unstuff macgs-510-files.sit.  It will create a folder named 
Ghostscript on your disk.

[ 2 ] Unstuff one of the two application files, macgs-510-68k.sit or 
macgs-510-ppc.sit into the Ghostscript folder.  Remember to only unstuff 
one of them!  The Finder gets confused if you have more than one version of 
an application on a disk.

[ 3 ] Unstuff macgs-510-fonts.sit into the Ghostscript folder as well.  
This exactly the same collection of fonts as 
ghostscript-fonts-std-3.0.tar.gz, just in a format most Macintosh users can 
handle.
 
You will only need macgs-510-src.sit if you are planning on compiling the 
program yourself.  See the chapter "Building It" for more details.



Starting

Launch the application.  By default, it will show you the Ghostscript 
console window, where you can see messages to and from Ghostscript.  After 
a few seconds, all initialization will be done and you will see the ŒGS>Ή 
prompt in the console window.  You donΉt actually have to wait for the 
prompt to begin using the program, anything that needs to wait for the 
prompt will do so automatically if you do it too early.



Getting Help

The program makes extensive use of Balloon Help.  Turn it on and explore!

Rendering a PostScript File

Choosing 'Open' from the 'File' menu lets you choose any TEXT or EPSF file.  
When you open a file this way, a new window is created, it is presented to 
Ghostscript for interpretation.  This (usually) results in rendering the 
first page of the file into the window.

If there are more pages in the file, you will see a small alert box with 
two buttons: 'Next Page' and 'Interrupt'.  Clicking the first will clear 
the window and let Ghostscript continue on with the next page in the file.  
Clicking the second asks Ghostscript to cancel processing the rest of the 
file.

Once a file has been rendered, it stays on the screen.  You can resize, 
scroll it, save it (as a PICT file), copy it (to the clipboard).  You can 
have as many windows open as memory allows.

Printing a PostScript File

After opening a document, you may print it by choosing the command 'Print' 
from the 'File' menu.   A "settings" dialog is presented for you to adjust the
imaging options.  Next, the standard print dialog appears and the user may
set the page range or print the entire document.  If a page range is selected, 
then the MacGS make take some time and consume a considerable amount of 
memory skipping to the pages to be printed.


Settings

You can change the settings of output media with the "Settings" dialog.  
Open this dialog by choosing "Settings..."  from the "Edit" menu.  There 
are three major sections:

Page Size lets you set the size of the 'logical' page.  This is the size 
that the PostScript file works with.

Scaling lets you enlarge or reduce the 'logical' page to produce the actual 
output you see.  This scaling happens conceptually after the page is 
printed.  However, Ghostscript is aware of this final scaling and will 
adjust some parameters accordingly (such as halftone screen, or any other 
parameters that are in 'device coordinates').

Image Options let you select options that pertain to how the image is 
rendered and recorded.

For example, if you want to render a document that was designed for a 
Letter size paper, but you want the output to be reduced to half size, then 
choose "US Letter" for the Page Size and "Half" for the Scaling.

There are too many controls and options in this dialog to discuss here: 
Turn on balloon help and explore it!

The options apply to all devices (see below), except Image Options which 
only apply to the 'mac' device.


Using MacGS as a Web Helper Application

You can use MacGS as a helper application for your web browser.  The 
following steps show how to configure the Netscape browser.  If you are 
using a different browser, the configuration will be similar:

[ 1 ] In the Preferences section called Helper Applications, check to see 
if there is a Mime type application/postscript.  If there isn't, then click 
New...  and create one: In the dialog that appears, set the type to 
application, and the subtype to postscript, then click OK.

[ 2 ] Select the application/postscript Mime type by clicking on it.

[ 3 ] Set the extensions by typing ai,eps,ps into the Extensions field.

[ 4 ] Set the application by clicking the Browse...  button.  In the dialog 
that appears, choose the MacGS application and click OK. Then choose the 
File type TEXT from the pop-up menu.

[ 5 ] Set the action to Launch Application.

[ 6 ] Click OK in the Preferences window to save the changes.

Some browsers, though not Netscape, may need to be restarted before the 
change will take effect.

IMPORTANT: Postscript includes operators for manipluating files.  A buggy 
or malicious postscript file could damage the files on your harddisk.  To 
minimize this risk, you should start MacGS and set the command line in the 
Preferences to: -dSAFER

This disable a number of file operations in Ghostscript.  Note that there 
are two problems with this: (a) This option does not claim to be fool proof 
- Postscript is very powerful and this option can't guard against all 
possible problems.  (b) You will be unable to render to any of the file 
devices when this is set.  However, you still be able to save what you 
render to the screen as PICT files.

To turn off this feature, you need to remove -dSAFER from the command line 
in the Preferences dialog, then quit and restart MacGS. Rendering to a File

Ghostscript supports a large number of graphic output formats.  Ghostscript 
calls these devices.  When your copy of the Macintosh port of Ghostscript 
was built, some devices were chosen to be included.  Since there are over a 
hundred devices, generally not all were included.  When you run the 
application, the devices that are included are listed in the 'Devices' 
menu.  The first one is always 'mac', which is the device for rendering 
into a Macintosh window.

To use another device, and cause Ghostscript to render into a graphic file, 
choose the device from the Device menu, and then open the file as normal.  
This time, instead of a new window appearing, you will be asked to named a 
file to hold the output.  The settings dialog can be used to set the page 
size and scaling options.  Note that the image options have no effect on 
other devices.  To switch back to rendering into a window, just choose 
'mac' from the 'Devices' menu.

Stopping the Application

You can attempt to interrupt Ghostscript from whatever it is doing with the 
<command><period> key sequence (it is also available as 'Interrupt' in the 
'Ghostscript' menu).  Interrupting a PostScript program is inherently 
unpredictable.  This is because a PostScript file can trap the 
user-interrupt and refuse to stop!  Interrupt is implemented so that it 
should work smoothly in most cases, but you can't be sure.  If it doesn't 
work, hit it a few more times.

Similarly, Quit is also something that a PostScript program can refuse to 
do!  Sometimes, Ghostscript may not appear not to quit.  Always give it a 
few seconds to try.  If it just won't quit, the work around is to type: 
<option><command><escape> (all at once) to invoke the System 7 Forced Quit 
dialog.

About Rendering

Ghostscript interprets PostScript programs and renders the graphics that 
they output.  The resulting output image is invariably device dependent.  
Indeed, the original PostScript file is the device independent form of the 
image.

Even though the images that Ghostscript renders can be saved in PICT files 
or on the clipboard in PICT format, these are still device dependent 
versions of the image: they will not scale well, nor will they display well 
with different numbers of available colors.  These PICT images are simply 
pixel graphics, not object-oriented graphics.  (If you examine these PICT 
files in a graphics program, you will notice that they are just a single 
large pixel map.)

 The Macintosh device currently renders to any of the following 
 characteristics (which you control in the Settings dialog): 72 dpi 1, 4, 
 or 8 bits per pixel standard Macintosh palettes for 4-bit gray, or 8-bit 
 color

These choices must be made at the time Ghostscript renders an image so that 
Ghostscript can do its best.  For example, Ghostscript will use halftone 
screens to achieve colors not in the palette.

Though the scaling options may change the dpi from the point of view of the 
PostScript program, the resulting image on the screen (obviously, as we 
can't change your hardware on the fly!)  and as saved in a PICT file, is 
72dpi.  For example: If you choose a scaling option of a "Third", the 
PostScript program appears to render on a 24dpi device, as 24 pixels make 
up an inch.  On the screen, however, 24 pixels make up a third of an inch 
at 72dpi, thus achieving the 'Third' scaling factor.

The standard Macintosh 8-bit palette is a color cube of 6x6x6 values in RGB 
space.  In addition, it adds evenly spaced ramps of 16 values each of red, 
green, blue, and gray.  Using this palette allows Ghostscript to render 
with out having the change the palette of a normal 8-bit display system.

Preferences

There are a number of application settings that can be set with 
"Preferences" dialog.  Open this dialog by choosing "Preferences..."  from 
the "File" menu.  There are three major sections:

Command Line lets you choose what the command line is for starting 
Ghostscript.  Generally leaving it empty is fine.  You can also choose to 
have the program ask you each time the program starts.

Windows and Dialogs let you set which windows are shown at start up, and 
how to handle the Next Page condition.  You can choose to have either a 
sound play or a small dialog appear, or both, when Ghostscript is waiting 
to display another page.

Remember lets you choose what information is remembered from one invocation 
of the application to the next.


Command Line

By default, Ghostscript is started with a blank command line.  This can be 
changed in two ways.  First, you can set the command line in the 
preferences.  Second, you can set the preferences to ask you each time the 
application starts.  In this mode, when you start the program, you will see 
a prompt for command line options in the console window.

Almost everything that can be set on a command line can be set after 
Ghostscript is running either through the Settings dialog, or by typing 
into the console window.  However, there are few command line options that 
can be useful:

 -v      prints version information and then quits
 -?      prints help information and then quits
 -dDEBUG turns on debugging during initialization

Do not set either of the first two as part of a default command line in the 
Preferences dialog, or each time you start it, Mac GS will display the 
information and quit.

Building MacGS

If you want to build the release (so you can configure Ghostscript to
your liking), you will need the current Ghostscript release and
the macintosh specific files.

From the standard Ghostscript ftp site, obtain the following files:

in directory /ghost/aladdin:
    
    gs5xx.tar.gz - .ps and .doc files - source files - headers and make files
    ghostscript-fonts-std-5xx.tar.gz - the fonts

where xx is the latest version of Ghostscript.  The fonts listed above are 
identical to the ones in the Macintosh distribution.

in directory /ghost/aladdin/mac:
    
    macgs-510-src.sit - source files

in directory /ghost/aladdin/510:
    
    ghostscript-5.03jpeg.tar.gz
    ghostscript-5.03libpng.tar.gz
    ghostscript-5.03zlib.tar.gz

In the standard method of building Ghostscript, all of these files (except 
the jpeg/libpng/zlib) get unpacked into one big directory.  The supporting library
stuff gets unpacked into a directory called jpeg-5a in the main directory.  The 
macintosh stuff also gets unpacked into its own directory, called 'Mac 
Specific'.  However, if you like (and I do) you can divide up all these 
files into the following hierarchy:

    Ghost Dev
        files -- all *.ps, *.doc, and other non-build files
        fonts -- all the fonts
        gs5.03 -- *.c, *.h, *.mak
        jpeg-6a -- the jpeg files
        libpng-0.96 -- the libpng files
   	   zlib-1.0.4 -- the zlib files
        Mac Specific -- the mac files

Once you get everything laid out, take a look at the file Worksheet in the 
mac specific folder for steps to build the system.


Known Bugs

‹ If a PostScript redefines 'quit' or if Ghostscript is seriously locked in 
an infinite loop you won't be able to quit.

‹ Preferences files moved to a machine with a smaller screen may have 
problems if window positions were remembered

‹ Open AppleEvent doesn't do a sanity check on file type

‹ Quit AppleEvent processing should be more intelligent

‹ The font and file directories can't be aliases

‹ Low-memory situations are not always handled gracefully.  If it crashes 
on you, try changing the Settings to use less memory per image, not opening 
as many images at a time, and/or increasing the memory allocated to the 
application.

‹ There is a rare symptom whereby the windows of the Finder redraw into the 
graphic windows.  A crash often follows.


Coming Enhancements

Features for future releases that I'm considering (these are in no 
particular order):

‹ Handling of Macintosh installed Type 1 Fonts
‹ Using QuickDraw to render TrueType fonts
‹ Printing (by sending the PS source)
‹ Offer Page menu on PDF files
‹ Scrolling the image via the HyperCard/MacPaint hand user interface
‹ Page settings as a 'windoid' palette
‹ Better dialog box look and layout for all dialogs
‹ Option key on Open AppleEvent to mean ask for settings first 
‹ Rotation and Cropping as device settings
‹ AppleEvents for controling settings and sending PostScript
‹ Command files (non-rendering script files)
‹ Mac device image options: 8bit gray scale and 4bit & 24bit color

Credits

MacGS-510 was written by Jeff Schindall.  While it is a substantially 
updated port of Ghostscript to the Macintosh, the previous port by Mark 
Lentczner served as inspiration and a starting point.

Mac GS Viewer 1.0 was written by Mark Lentczner of Glyphic Technology.  
While it is a substantially a new port of Ghostscript to the Macintosh, the 
previous port by Martin Fong served as inspiration and a starting point.

Ghostscript was created by L. Peter Deutsch of Aladdin Enterprises.  Please 
see the document README in the files directory of the release for more 
information.

MacGS could not have happend without the faithful help of over fifty beta 
testers.  A tip'o'the mouse to them !


MacGS is distributed under the Aladdin Ghostscript Free Public License.  
See the file PUBLIC in the files directory of the relase for the full text.  
As a piece of free software, neither Aladdin Enterprises.  If you have 
questions please try the news group comp.lang.postscript, where Ghostscript 
is discussed.

If you are interested in licensing all or any part of the Ghostscript 
system, including MacGS, please the information in the file README in the 
files directory of the release.



Contacts

MacGS is part of the Ghostscript system which is discussed on the Internet 
news group: comp.lang.postscript

Ghostscript's public FTP site is:
    ftp.cs.wisc.edu
in the directory:
    /pub/ghost

Information on Ghostscript can be found on-line at:
    http://www.cs.wisc.edu/~ghost/index.html

Aladdin Systems can be reached at:
    ghost@aladdin.com

Macintosh related questions should be directed to
    mac-gs@aladdin.com