Extracting FEA from a opentype font

Sami Artur Mandelbaum

I am trying to extract all the GSUB, GPOS and GDEF tables from a font.
I am using adobe source code pro (open source) and this font has Characther Variants features with featureParams.
I have tryed exporting using fontlab VI, DTL Otmaster 6.3 and even AFDKO spot.
Fontlab VI and DTL OtMaster 6.3 cant export character variants features with featureparams.
AFDKO spot show the featureparams but when I import in OtMaster I need to do a lot of changes.
Please, Is there a program or a line command to extract the FEA and importing in OtMaster withou a pain?
I am trying to use ft2fea.py but I don't know how to use or install.
Any help is apreciated.
Sami

Mark Simonson

Sorry, but that's like trying to extract the source code from a compiled binary app.

Simon Cozens

Away from my computer so I can't give a full answer, but I've had the best results doing this from FontForge. Short description how to do it here: https://simoncozens.github.io/fonts-and-layout//features.html

Try fontforge, and look into getting ft2fea working if that doesn't do what you want. The previous chapter of my book also tells you how to install fonttools, which is a prerequisite for ft2fea. Let me know if you have any problems getting fonttools installed and we can take it from there.

Sami Artur Mandelbaum

Mark Simonson said:

Sorry, but that's like trying to extract the source code from a compiled binary app.

Hi Mark,
the reason I chose this this font is because it has SIL Open Font License.
I believe the purpose of this type of font licence is You learn how to make and improve a font.
I have no intention to use this kind of hacking in a comercial font.

Hi Simon,
I am a windows 7 user and I dont know how install fontools.
I use afdko because it has a windows version with "bat" and "exe" files.
But without an installer I am lost.
Please your help is more than welcome.
Regards
Sami

Paul van der Laan

Why do you need to extract this data from the binaries if Adobe has made all the source files for this font available?

Mark’s comment has nothing to do with copyright infringement. If you extract data from a generated font binary you won't always get the original source code. Some things, such as OpenType features, need to be disassembled.

Sami Artur Mandelbaum

Paul van der Laan said:

Why do you need to extract this data from the binaries if Adobe has made all the source files for this font available?

Hi Paul, thank's for the link, but in this link I didn't find the GSUB.fea only GPOS (mark and mkmk).
I would like to see the how adobe does the character variants features with featureparams.

Khaled Hosny

The GSUB stuff is in the top level family.fea file that other files include: https://github.com/adobe-fonts/source-code-pro/blob/master/family.fea#L292

Sami Artur Mandelbaum

Khaled Hosny said:

The GSUB stuff is in the top level family.fea file that other files include: https://github.com/adobe-fonts/source-code-pro/blob/master/family.fea#L292

Thank You Khaled!

Sami Artur Mandelbaum

I did some tests and only AFDKO can compile correctly CVxx with featureparams.
Fontlab VI and DTL OTMaster failed in compile the original GSUB from adobe source code pro and Fontforge didn't even show the CVxx lookups.
Is there any font program can compiled correctly CVxx with featureparams?
Maybe it's too soon for me to worry about these feature and I am loosing my time
Even adobe does not care about to put this opentype feature accessible in Indesign.

Erwin Denissen

FontCreator allows you to open and save fonts while preserving 99% of the OpenType features. It has full support for character variants (cvXX).

You can visually edit the OpenType layout features:


You can also edit the feature code:

Sami Artur Mandelbaum

Hi Erwin,
I have downloaded your evaluation version of Fontcreator 10.1.
I have tryed to import the orginal GSUb.fea from Adobe source code pro but the program couldn't compile.
What is the difference from your .otlfd format from fea format?
Regards
Sami

Erwin Denissen

Our feature code format is based on OpenType Compiler. It is similar but not equal to VOLT or AFDKO, but since FontCreator can decompile the binaries from the font, it is far easier to just open the font and go from there.