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Almathera Ten Pack 2: CDPD 1
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DPS
Version 1.1
Author: Allen Norskog
April 23, 1989
PUBLIC DOMAIN NOTICE
This program is placed in Public Domain. It may be freely copied.
I developed this program to suit my own needs. I hope it will be
useful to others. The source is included so that you can make
modifications to suit your own needs. I would appreciate any comments
or bug reports.
DESCRIPTION
DPS is designed to work with the PrintScript program by Pixelations
to provide a page previewer. PrintScript is a PostScript interpreter.
Presently, PrintScript does not include a screen previewer. This
program addresses this shortcoming. PrintScript does have the ability
to write a "bitmap" picture to a file. This program reads in such
a file and displays the "page" on the screen.
The main motivation behind DPS, was to have a tool that would show
one's mistakes, such as printing off the page, or not getting things
centered. For this, one would like something quick. Generating
a file for DPS is not really quick, but can be two to three times
faster than actually printing.
DPS uses a lower resolution picture than what you will probably
finally print. The advantage here is that the smaller picture takes
less time to compute. Also, the picture file takes less disk or
memory space than if you generated a hi-res image file.
Presently, DPS is set to display one fixed page size -- 8.5 by 11 inches.
How it appears on the screen is dependent of course on your monitor.
With a standard Amiga monitor, it will actually be a bit larger. Also
the image will be slightly tall - you will notice this a bit, for
example, when drawing a circle.
Originally, what I thought I wanted was a full page overview, like that
in the "Overview" window. Since I couldn't get PrintScript to generate
less than 72 dpi, I had approximately twice as many dots (pixels) in each
direction than what I originally wanted. Having the dots available
anyway, I did the larger main window, and have generally liked it
better. One can see the details much more clearly in the main window.
The Overview window is compressed 2X in both directions compared to the
main window. Each pixel in the Overview image represents 2x2 pixels
in the main window. If any of the pixels in the 2x2 square is black,
the corresponding pixel in the Overview window will be black. This
makes sure that (normal black) lines don't disappear -- if you are
going to be printing something in that area, you will see something
on the screen. However, gray areas get darker (or totally black)
on the Overview window.
CONFIGURING PRINTSCRIPT
DPS uses the file output feature of PrintScript. This file describes
the image in a run-length-encoded manner documented in the PrintScript
manual. For DPS to work properly, you need to specify that you are
going to use an 8.5 by 11 inch page, with no margins, and at 72 dots
per inch.
You need to run the configuration program on the PrintScript disk to
create a configuration file (Config.ps) that tells PrintScript to write
to a file. See the manual for information. Below is a sample session:
1> configure
Screen frequency (10-360)? 10 (You may choose from 10 to 72)
Screen angle (0-90)? 45 (You may choose 0 to 90)
Are you using a preferences printer (Y or N)? N
Width of printable page in inches (1.0 - 14.0)? 8.5
Height of printable page inches (1.0 - 14.0)? 11
Horizontal dots per inch (72-360)? 72
Vertical dots per inch (72-360)? 72
Printer port name or filename (par:, ser: or file)? ram:dps_file
Name of printer driver? File
Unprintable left margin in inches (0.0 - 1.0)? 0.0
Unprintable bottom margin in inches (0.0 - 1.0)? 0.0
You may choose a file name other than ram:dps_file. Just remember
what you called it so you know where to find it. The file generated
will generally not be too large because of the low resolution
and the compression used. Thus, you should be able to usually write it
to ram: to speed things up.
The first two questions in the configuration example shown above
relate to settings for half-tone images. You may want to experiment
with values here. See the PrintScript manual or a PostScript manual
for more info.
After you run PrintScript on your PostScript file, the output file
should be available to use in DPS.
RUNNING DPS
DPS can be run from either the CLI (like PrintScript), or from the
Workbench.
From the CLI:
You simply type dps followed by the file name. If you ran the
configuration as described above, you would enter at the cli prompt:
1> dps ram:dps_file
From the Workbench:
The file that DPS will be looking for is given in the ToolTypes for
the DPS icon (info file). Find the DPS icon. Click on it once.
Select the Workbench-Info menu item from the Workbench screen.
Change the ToolTypes line, so "FILE" is pointed to the file you
want. For example, if you used the above configuration, you would
set the line to be:
FILE=ram:dps_file
Save the changes you made to the info file. Now the DPS icon is
ready for use. Double click on the icon to run DPS.
When the DPS program is first loaded, it checks if the file specified
is really a PrintScript file. If the file is okay, it will build an
image for display. DPS will open a custom interlace screen. A gray
page was chosen to reduce flicker. The writing on the page will be
black. A page outline is displayed, so you can see where the "edges"
will be. If you write to the edge, that area of the edge will be
reversed, so you can tell that you are attempting to write there.
You are probably too close for what your printer will do.
A slider along the right allows you to scroll up and down the page.
You can exit DPS by hitting the "close button" in the DPS window, or
use the "Quit" menu option.
Another menu item is labeled "Overview". Selecting this will bring
up what was intended to be a full page view on the screen. Actually,
it is a couple lines short, so a slider bar is also provided in the
Overview window as well. The image in the Overview window is half
as wide and half as tall as the image in the main DPS window. Closing
the Overview window returns you to the main DPS window.
ERRORS
The file you specify will be checked to see if it is a PrintScript
type file. If the beginning of the file is not set up like it expects
(see the header definition in the PrintScript manual), it will assume
that you are trying to read a non-PrintScript file. DPS will display
a message describing the problem and the program will exit. Actually
DPS will only require that the "version" be 1 and that "flags" be 1.
All the other fields are ignored for now, so it is important that you
use the setup described above.
If DPS is started from the CLI, any error messages will be displayed
in your CLI window. Thus, you can have a log of any error messages.
If the program is started from the Workbench, error messages may
be displayed in requestors, or a text window that displays briefly.
MISCELLANEOUS
To let you try the DPS program, an example file (dps.circle) is
included. This file was generate with PrintScript using an adaptation
of one of the example programs in the Adobe "PostScript Language
Tutorial and Cookbook". To try it type at the the CLI prompt:
1> dps dps.circle
OR double click on the dps icon. The icon has the ToolType set for
"FILE=dps.circle", so that the demo can be readily seen. Change
the Tool Type entry as described above for actual use.
Allen Norskog
900 Whaler's Way
Fort Collins, CO 80525
--------------------------
Trademark acknowledgements
PrintScript is a trademark of Pixelations
PostScript is a trademark of Adobe Systems, Inc.