Typophile

FontLab, OpenType, Mac and AAT?

robertm

Using my brand new copy of FontLab, I've put together my first OpenType font. Unfortunately, I don't think I understand everything yet and I have a few questions for the experts. (Please forgive me if these questions sound a little stupid.)

My font is a basic CFF .otf font with upper case characters and alternate figures. I use the aalt and salt OpenType features and it works in the FontLab preview on Panther.

1) I was surprised to see that 1/3rd of my applications have no idea what OpenType might be at all (Word, etc.). 1/3rd work just fine and I can access the alternate characters (these are Adobe applications which seem to use their own font engine) and the last third of my applications (such as TextEdit, or Freeway) claim that there are "no typographic features" in the font (but I can use the character palette's glyph input to see the alternates) . It seems that Apple wants me to put AAT tables in the font, but how can I add these tables? The Apple tools apparently only like TrueType flavored OpenType fonts? Help!
My salt feature is really simple (and accesses two FontLab classes):
feature salt { # Stylistic Alternates
sub @figures by @altfigures;
} salt;

2) To make the font more usable, I want to "copy" the upper case glyphs to lower case. I tried adding additional Unicode indexes as per page 95 of the FontLab manual. FontLab proudly shows the little "D" icon at both locations and the preview seems to indicate everything is fine. Unfortunately, applications only seem to display the first index and either nothing (Adobe) or the default Font (Apple) for the lower case!? I can of course cheat and just duplicate the glyph (or use a "composite" with only one component).

3) When I add the OpenType "size" feature, FontLab crashes when compiling the features. Does anyone know whether that's a known problem (or something FontLab just doesn't support), or should I report this?
The following is the example from the Adobe web site. I removed the sizemenunames.
feature size {
parameters 100 # design size (decipoints)
3 # subfamily identifier
80 # range start (exclusive, decipoints)
139; # range end (inclusive, decipoints)
} size;


Thanks for your time!
Robert

robertm

I've since found a very inconvenient answer to #1. But it works and it could be automated (anyone?).

1) Use TTX 2.0b1 http://sourceforge.net/projects/fonttools/ to dump the original OpenType font. The resulting .ttx file will have <glyphorder> at the top which maps GlyphIDs to names. Get the IDs for the glyphs that will be substituted.

2) Create a "mif" file with the following contents (the list is the substitution list) 

 
Type          Noncontextual 
Name          Character Alternates 
Namecode      17 
Setting       No Alternates 
Settingcode   0 
Default       yes 
Orientation   HV 
Forward       yes 
Exclusive     yes 
 
Type          Noncontextual 
Name          Character Alternates 
Namecode      17 
Setting       Alternates 
Settingcode   1 
Default       no 
Orientation   HV 
Forward       yes 
Exclusive     yes 
 
        10      58 
        11      63 
        12      57 
        13      66 
        14      61 
        15      60 
        16      65 
        17      64 
        18      59 
        19      62


Unfortunately, I haven't fgured out a way to use my fancy names ("zero.2") instead of the GlyphIDs which might change when messing around with the font too much in FontLab.

3) Run ftxenhancer -m miffile myfont.otf
(Apple font tools, http://developer.apple.com/fonts/)

The resulting CFF OpenType file will work in AAT aware applications as well as in OpenType applications.

Ian Blair

Apple's font tool DumpPOST creates a text file with the Postscript names for all the characters in the font. The PS names can be changed in a text editor and appended to the font with the AAT Font Tool. These are 'classic', pre-OSX applications. In OSX, ftxdumperfuser may do the same job (I've not used it).

robertm

The post resource version 3 doesn't have glyph names; I think I'll stick with ttx (I'm using the latest from CVS).

There was one additional hurdle: Panther ignores the OpenType kerning information when AAT information is present.

To fix this, I simply add a 'kern' table to the font which FontLab conveniently generates when it saves a PC TrueType font.

1) In FontLab, save font as PC ttf AND CFF-otf

2) Run magic script: 

 
#!/bin/sh 
NAME=MyFont 
 
ttx -t kern $NAME.ttf 
sed -e 's/ttFont sfntVersion=\"\x00\x01\x00\x00\"/ttFont sfntVersion=\"OTTO\"/'  <$name.ttx> $NAME.kern 
rm $NAME.ttx 
 
mv $NAME.otf $NAME.otf.fl 
ttx -m $NAME.otf.fl $NAME.kern 
rm $NAME.kern 
 
echo "Adding 'morx'  table..." 
ftxenhancer -m $NAME.mif $NAME.otf 
 
echo "*** BUILD COMPLETE ***"


3) Trash the PC ttf.

Robert

John Hudson

Robert, how are you making fonts with version 3 post tables? Just interested to know what your procedure is.

robertm

FontLab (4.6, Mac) just did it, it didn't ask (I've only used the program for a couple of hours and I'm still somewhat mystified by its functionality).

I use File->Generate Font->OpenType-CFF. The display next to the Options box says: "Type 1 options: make PFM, make AFM; Unicode encoding; TT/OTF options: hinted (keep, autohint, visual); export Unicode;
I think that these options aren't relevant when writing OT/CFF.

See picture for the FontLab OpenType preferences dialog.

Robert

OT preferences

John Hudson

FontLab (4.6, Mac) just did it, it didn't ask...

It may be that, if making a PS OTF, FontLab writes the glyph names to the CFF table (I believe there is a place to store them there) and so writes a version 3 post table. That actually makes sense. I mainly work with TrueType fonts, for which FontLab writes a version 2 post table. I recently had to make a TT font with a version 3 table, and ended up needing another tool to do this.

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