Rob McDougall writes:
> Wirt, would you mind detailing a couple of examples of those things that
> cannot be created on a PCL printer? With the addition of HP-GL to PCL5
> (several years ago), all the obvious things like shaded/rotated text
> became possible. I'm not aware of any functionality that would be of
> use to a forms user that is missing from PCL.
Clipping paths, which are very useful for any number of graphic constructions,
including elaborate text constructions, are just one obvious item that's
missing from PCL. But constraining the discussion to only those items that are
more likely to appear on a standard business form, I've included the
PostScript fragment that generates our company logo. Logos are clearly a very
important feature of a standard business form. Our particular logo is a
stylized Easter Island statue, incorporating a number of rounded corners, set
in a box with the word, "AICS", appearing at the base.
More importantly, the logo, as an object, is scalable to any size, postage
stamp to football field, and will never appear with any greater jaggies in the
image than the rendering printer generates at its maximum resolution. More
importantly yet, it is a drop-on object that does not disturb the graphics
state -- and allows itself to be presented at any rotation, in any color
scheme the user wishes to present it.
[As an explanatory note, the code below uses two variables named "lcolor"
(light color) and "dcolor" (dark color). They are the only two color variables
used in this example and are set by the user on the spreadsheet when he or she
specifies the logo's position and scale factor on the page].
I'm reasonably familiar with PCL 5, but I would very much like to see someone
create this logo in PCL, replete with all of these salutory attributes.The
rendering time for this logo is almost instantaneous, as is obviously its
download time.
=======================================
/l {lineto} def /m {moveto} def /c {curveto} def
/n {newpath} def
/logo {0 -324 translate 4 4 scale 0 setlinejoin 0.4 setlinewidth
n 0 0 m 0 81 l 53 81 l 53 0 l closepath gsave lcolor fill
grestore dcolor stroke 1 setlinejoin .8 setlinewidth
5 21 m 5 76 l 48 76 l 48 21 l closepath dcolor fill
20 27 m 28 27 37 34 37 35 c 33 70 l 26 70 20 69 20 68 c
18 60 l 20.5 59.5 l 18 48.5 l 20 48 l 18.2 40 l 18.2 39.7 18.7 39.5
19 39.4 c 21 39.5 l closepath lcolor stroke
20.5 59.5 m 26 58.5 l 26 58 25 57.5 23.5 57.5 c 22 57.5 21 58 21 59 c
closepath lcolor gsave fill grestore stroke
20 48 m 23.3 47.3 l 19.5 46 l closepath lcolor gsave fill
grestore stroke
21 39.5 m 29 41 l 29 40 22 35 21 35 c closepath
gsave fill grestore stroke
/AvantGarde-Book findfont 17 scalefont setfont dcolor
7 4 m (AICS) show} def
gsave logo grestore
========================================
Rob also writes the following about my claim that PCL is rarely (if ever) used
for professional publications:
> I think this statistic is misleading. I don't believe that the fact
> that high end publications are produced using Postscript is directly
> related to the quality of its output. It's more related to history than
> anything else. Postscript was in use within the printing industry long
> before the first LaserJet rolled off the assembly line in Boise. Like
> our faithful HP3000, it works and nothing substantially better has come
> along so there's no reason to switch. High end layout packages all
> support Postscript because that's what the high end printing presses
> support. The only reason they support Postscript is because that's what
> they've always supported.
As a bit of highly personalized history of these two printing languages, let
me say these few words: PCL is older than PostScript -- and is about the same
age as JAM (PostScript's progenitor), thus age can't be used as a complete
explanation.
I've paid close attention to both languages for twenty years now. In about
1980 (plus or minus a bit), when the first LaserJet appeared, I went to our
local HP office to see what all of the new excitement was about, but I came
back quite disappointed. Because the then-brand-new LaserJet's bitmapped fonts
were simply digitized photographs of letters, the quality was terrible. I came
back that day and told my wife that Benjamin Franklin would have considered
this "advance" a step backwards in printing technology.
However, within six months to a year of that first appearance, Bitstream
straightened up the HP LaserJet's fonts by simply taking more care in putting
the fonts together -- and that improvement more than made the first LaserJets
acceptable substitutes for line printers. But that's basically all they were.
However -- and it was a big however -- a few years later, in late 1983, I saw
my first Macintosh and was blown away by the quality of John Warnock's
PostScript printing language.
At about the same time, HP announced that they were going to adopt the Imagen
DDL printing language as their new page description language. Given the
extraordinary quality of PostScript, I thought that they were making a
substantial mistake and spent much of the early part of 1984 calling various
people at HP. I strongly advocated PostScript as the direction where they
should be moving.
Two things worked against my advice having any affect. I was quite naive in
those days on how to politely request change -- and HP was in a phase where
listening to users was not particularly high on their list, as Alfredo, Steve
Cooper, and others on this list will readily tell you. Rather, HP assured me
that Imagen DDL was going to be the full equivalent of PostScript and that
their support of Imagen was 100%. And they resolutely maintained that level of
commitment for a full six months before they dropped it.
In Imagen's place, HP began elaborating the escape control sequences that they
had put into the early laserjets (which are the same control sequences that
were used in the HP264x series of terminals) and named this collection,
"Printer Control Language."
As I said, I thought that this was a fundamental mistake, given the
extraordinary differences in quality that existed between PostScript and the
then-minimal capabilities of PCL. But I was dead wrong. In fact, I consider my
early, strong advocacy of PostScript to be one of my greatest miscalls to
date.
Adode Systems is not an easy company to deal with even today -- and in the
early days, they were far too greedy. An Apple LaserWriter (a PostScript
printer) cost $4500. An HP LaserJet II cost $2500. As a result, HP printers
outsold Apple printers at the rate of 100 to 1. If Adobe had understood what
it had -- and priced PostScript in the same manner that Bill Gates prices his
products -- PCL wouldn't exist now.
Quality matters -- but price matters much more.
Because of the LaserJet's explosive success, and because at the time, the
"one-vendor solution" (the complete opposite of today's "open systems"), was
all the rage, we too dropped PostScript and supported only HP's PCL through
versions PCL II, PCL 3, PCL 4, and finally PCL 5. However, I continued to
write polite letters to HP pointing out the deficiencies of PCL. I was
ultimately told to wait for PCL 5. It would be "the equivalent of PostScript."
When PCL 5 did finally arrive, I was again greatly disappointed. But HP
continued to promote PCL 5 as the equivalent of PostScript and scheduled a
talk at the 1990(?) Interex Orlando conference with precisely that title. I
wrote the author a letter a month or so before the conference, detailing all
of the deficiencies of PCL 5 vis-a-vis PostScript and outlining my
disappointment. He never responded. His only reaction was to cancel his talk.
Nonetheless, we felt we had no alternative but to continue to support PCL
encoded graphics. But in ca. 1992, HP finally brought genuine Adobe PostScript
to the LaserJet III as an inexpensive plug-in cartridge -- and that was enough
for us to decide to switch over entirely to PostScript.
PostScript on the LaserJet III didn't work well. It was slow and buggy. But HP
got PostScript dead right on the LaserJet IV. It took us two years to scrub
all of the PCL code out of QueryCalc and convert it over exclusively to
PostScript, but it's a decision I've never regretted. It has made life
enormously easier for us and for our customers. But more than that, we've
extremely well positioned for the future for five years now, which is very
high quality, easy to maintain color laser printers. This is what business
people want -- and the prices of the new printers are getting to point that
resistance is going break as a rush of new products appears.
Wirt Atmar
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