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MacGS-510
A port of Aladdin Ghostscript to the Macintosh
Version 5.10 - December 15th, 1997
Ghostscript by L. Peter Deutsch
MacGS-510 & Macintosh drivers by Jeff Schindall
Copyright (c) 1997 Aladdin Enterprises, Menlo Park, CA.
All rights reserved.
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-510 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 '.doc' in the
'files' folder for more information.
The release consists of the following files:
- macgs-510.sit
- Ghostscript application, files, fonts, and documentation
- 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.
- Unstuff macgs-510.sit. It will create a folder named
Ghostscript on your disk.
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.
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 'GS>' prompt in the console window. You don't 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.
The program makes extensive use of Balloon Help. Turn it on and
explore!
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.
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.
Choosing 'ps2pdf' from the 'Ghostscript' menu lets you choose any TEXT or
EPSF file for pdf distillation. Next you will be prompted for an output
file save location. When you open a file this way, a pdf file is created,
and the input is presented to Ghostscript for distillation. This (usually)
results in the creation of a pdf file.
You can also distill to a pdf file by dragging a file to the
MacGS-510 icon while holding down the option key.
Once a file has been distilled, the ghostscript command line prompt
appears in the console window.
Choosing 'ps2ascii' from the 'Ghostscript' menu lets you choose any TEXT,
PDF or EPSF file for text extraction. Next you will be prompted for an
output file save location. When you open a file this way, a TEXT file is
created.
Once the operation has concluded, the ghostscript command line prompt
appears in the console window.
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.
You can use MacGS-510 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:
- 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.
- Select the application/postscript Mime type by clicking on it.
- Set the extensions by typing ai,eps,ps into the Extensions field.
- Set the application by clicking the Browse... button. In the
dialog that appears, choose the MacGS-510 application and click OK.
Then choose the File type TEXT from the pop-up menu.
- Set the action to Launch Application.
- 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 manipulating files. A
buggy or malicious postscript file could damage the files on your
harddisk. To minimize this risk, you should start MacGS-510 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-510.
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.
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.
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.
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.
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.
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:
- gs5xxlib.tar.gz - .ps and .doc files
gs5xxsr1.tar.gz - headers and make files
gs5xxsr2.tar.gz - source files
ghostscript-fonts-std-5.0.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:
- jpegsrc.v6a.tar.gz - the jpeg library
- zlib.tar.gz - the zlib library
- libpng.tar.gz - the libpng library
In the standard method of building Ghostscript, all of these files
(except the jpeg) get unpacked into one big directory. The jpeg stuff
gets unpacked into a directory called jpeg-6a 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
- src
- *.c, *.h, *.mak
- jpeg-6a
- the jpeg files Mac
- Specific
- the mac files MPW
- Build
- empty directory used for building under MPW
Once you get everything laid out, take a look at the file Worksheet in
the mac specific folder for steps to build the system.
- 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. Avoid
settings that require more memory than you have allocated to the
application.
- There is a rare symptom whereby the windows of the Finder redraw into
the graphic windows. A crash often follows.
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
- Better handling of file include search path
- Parse DSC comments & Offer a Page menu
- Offer Page menu on PDF files
- Scrolling the image via the HyperCard/MacPaint hand user interface
- Console scroll back
- Console cut & paste and text file read & write
- Drivers and plug-in resources (would need support in GS)
- 'nn' style user interface for multi-page documents
- 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 controlling settings and sending PostScript
- Command files (non-rendering script files)
- Mac device image options: 8bit gray scale and 4bit & 24bit color
MacGS-510 is written by Jeff Schindall and is based on previous work
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-510 could not have happend without the faithful help of over
fifty beta testers. A tip'o'the mouse to them :)
MacGS-510 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 nor Glyphic Technology can offer any direct support for it.
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-510, please the information in the file
README in the files directory of the release.
- MacGS-510 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 Enterprises can be reached at:
- ghost@aladdin.com
- Jeff Schindall can be reached at:
- mac-gs@aladdin.com