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From: ajq@mace.cc.purdue.edu (John O'Malley)
Newsgroups: comp.sys.mac
Subject: Re: How do you tell a laser font?
Message-ID: <2371@mace.cc.purdue.edu>
Date: 11 May 89 15:29:00 GMT
References: <1796@husc6.harvard.edu>
Reply-To: ajq@mace.cc.purdue.edu (John O'Malley)
Organization: Purdue University Computing Center
Lines: 68

In article <1796@husc6.harvard.edu> hellerst@husc4.UUCP (Joe Hellerstein)
writes:
>Short of a visit to the friendly neighborhood laserwriter, how does one
>ascertain whether a given font has info. built in to make it nice
>and smooth on the laser writer?  Anything involved in making sure the
>font gets downloaded to the LWII besides having it installed in the System
>(using 6.0.2)?
>
>Joe Hellerstein

Here's my longish explanation of how fonts are printed on ImageWriters and
LaserWriters.  Netters, please post corrections to my explanation, if
necessary.

As I understand it, there are two major kinds of fonts:  screen fonts and
printer fonts.

The LaserWriter has 11 printer fonts built-in to it, such as Times,
Helvetica, Avante Garde, Palatino, Zaph Chancery, & Zaph Dingbats.

The ImageWriter has no fonts built-in to it, for all practical purposes.
Yes, it does have a couple of standard draft-mode fonts, but these are
more or less useless to Mac users (see below).

A screen font is that which you have installed in the System file on your
Macintosh.

To print a font on an ImageWriter, a Macintosh takes the screen font's
double, scales it down 50%, and then prints it.  That's how it achieves
fairly-good looking font output.  Example:  You have both 12- and 24-point
New York installed in your System file.  You want to print a document done
in 12-point New York.  You tell the Mac to print in "best" quality mode.
The Mac takes the 24-point screen font, scales it down 50% to 12-point,
and then sends the page to the ImageWriter.

So, when the double-size of a font isn't present, the Mac has to make
approximations.  This explains why a 12-point printout doesn't look very
good when the 24-point screen font isn't installed in your System.

A key point to recognize is that when you print a document on the
ImageWriter, the Macintosh does all the thinking.  It creates a bitmap
picture of the document within its memory, and then slowly spits out this
picture to the printer for printing.

When you tell your Mac to print in "draft" mode, it doesn't send any font
info at all to the printer.  It uses the built-in draft font.  That's
why you can't see New York output in draft mode.  The ImageWriter does the
thinking, so to speak.

To print a font on the LaserWriter, a Macintosh looks at the screen font
that you've used and sees if the equivalent printer font is installed in
the LaserWriter.  If so, then it sends the document to the LaserWriter,
which in turn uses its PostScript brain and built-in printer font to print
the page.  The major work is done by the LaserWriter, not the Mac.

If the equivalent font is NOT installed in the LaserWriter, you'll see a
message saying that a bitmap version of the font is being created for the
LaserWriter.  That's when the LaserWriter needs a "picture" (bitmap) of
the screen font in order to print it, since no built-in printer font is
available.  

New York and Venice are not built-in printer fonts on the LaserWriter.
Try printing out documents made with those fonts.  Then redo the same
documents using Times and Zaph Chancery and compare the results.


John O'Malley           / Macintosh  / Purdue University / (317)
mace.cc.purdue.edu!ajq / Specialist / Computing Center  / 494-1787