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Re: LY1 & 8r Encodings unsound!?!?


At 03:35 AM 1/2/98 -0800, Melissa O'Neill wrote:

>As many of you know, I've been playing with TFM files, Encodings and
>the like lately. Imagine my surprise then, when I found that some
>files that I'd made perfectly printable PostScript from, using a
>slight variant of the LY1 encoding wouldn't make good PDF. 
>When viewed
>on a Macintosh, the ff and fl ligatures were missing, and so were the
>quote characters.

Presumably you mean fi and fl, since Helvetica doesn't have ff-ligatures :-)

The Macintosh Acrobat Reader has in various versions exhibit variuous
bugs.  It has always been the winner in the Acrobat bug contest :-)
This is particularly true if you have the fonts that appear in the
PDF file also installed locally.  Sometimes you can work around
the problem by disabling the local fonts (using ATM or SuitCase II).

You may want to try the experiment with a font other than one you 
have installed on your machine or the ones built into the Reader
(Times, Helvetica, Courier, Symbol).

Also make sure you are not using 0, 9, 10, 13, 15 character codes.
Some DVI-PS drivers can avoid using `control characters'
for some fonts by mapping these character codes higher up automatically.

>To investigate further, I made some Encoding test files, not with TeX,
>but based on some handwritten PostScript I had, which draws a table
>with all the characters in the encoding. When I did this, I found that
>the PDF made from both the TexBase1 encoding and the TeXnANSI encoding
>didn't view correctly on the Macintosh Acrobat reader (although it
>printed fine).

>I've put my various test files (PS and PDF) on my web site, in
>``http://www.cs.sfu.ca/~oneill/personal/encodings/''. If you want to

Very nice.  They all look fine here on NT.

By the way, surround the http....encodings with white space, then most mailers
give you a clickable link :-)  Avoid putting quotes or periods and commas
before and after.  Some mailers are too dumb to cope with that.

>view them on your own Mac, bear in mind that you *must* quit Acrobat
>Exchange between each PDF file, because one file can influence the next.

>This looks like a horrible bug in Acrobat Exchange 3.01 for the
>Macintosh (and so clearly not our fault), and it's certainly a bug that
>doesn't always show up. Nevertheless, that it shows up at all seems
>like a problem, and casts a shadow of doubt over both these encodings.

It cast a shadow of doubt on any encoding that uses the control character
range (0-31).  but then without that you are down to 224 glyphs - just not
enough.  Adobe should fix the problem.  We have reported it to them many
times over the past few years.  Please bug them some more!

Regards, Berthold

Berthold K.P. Horn
MIT AI Laboratory
mailto: bkph@ai.mit.edu