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From: ldo@waikato.ac.nz (Lawrence D'Oliveiro, Waikato University)
Newsgroups: comp.sys.mac.system
Subject: TrueType versus ATM
Message-ID: <1991Mar20.164934.3177@waikato.ac.nz>
Date: 20 Mar 91 03:49:34 GMT
Organization: University of Waikato, Hamilton, New Zealand
Lines: 55

I've been doing some rough speed tests to see how TrueType compares with
Adobe Type Manager 2.0.

For my tests, I created a HyperCard 2.0 stack with a single text field and
a single card. I filled the field with about 760 characters (repetitions
of "The quick brown fox..."), selected the entire contents of the field,
and then checked out what happened on different choices of text font
and size.

My machine is a vintage Mac II running System 6.0.7. I've got the
TrueType versions of Courier, Helvetica, Symbol and Times installed,
while ATM handles the imaging for Avant Garde, Bookman, N Helvetica
Narrow, New Century Schlbk (sic), Palatino, Zapf Chancery and Zapf
Dingbats. The ATM cache size setting is its default 96K, with "preserve
line spacing" enabled. I have the 68020/68881 version of ATM loaded.

I should point out that all my timings are pretty rough, since they're
based on the seconds display on my wristwatch, and estimating half
seconds. But the differences in speed I observed I can definitely
vouch for.

The first time I chose a new ATM font, it took about 3 seconds to
redraw the text in the new font. For TrueType, this time was about
1.5 seconds. The update appeared all at once, which is probably
because HyperCard does the initial drawing off-screen.

Having chosen a font (initially in a 12-point size), I then changed
the text to 13 point, and then 14 point, 15 point etc. Changing
from 12 to 13 point invoked the same delay: 3 seconds for ATM,
1.5 seconds for TrueType. Subsequent changes showed a different
behaviour: TrueType kept updating at the same rate, while ATM started
updating in only a fraction of a second! It looks to me like ATM has
some kind of "lookahead" heuristic which says that, once I've used
two sizes of the same font, I'm likely to use a third.

I tried choosing a couple of other fonts for each of ATM and TrueType,
and observed the same behaviour in each case. Naturally, the second
time I choose the same font/size combination, the cache comes into
play, and redrawing goes a lot faster for both--in fact, there's no
difference in performance that I can discern in this case, nor is
there a loss of speed as compared to a bitmap font.

I haven't tried restarting my machine and redoing the tests a second
time, just to be sure. Would other people like to do their own tests,
and either confirm my observations, or show me up for
the dummy that I am?

I'm trying to get a discussion going here, so--comments welcomed...

Lawrence D'Oliveiro                       fone: +64-71-562-889
Computer Services Dept                     fax: +64-71-384-066
University of Waikato            electric mail: ldo@waikato.ac.nz
Hamilton, New Zealand    37^ 47' 26" S, 175^ 19' 7" E, GMT+12:00
To every glyph, kern, kern, kern,
There is a width and a side bearing, kern, kern, kern...