Mappings in a New FCP file

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ClintGoss
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Mappings in a New FCP file

Post by ClintGoss » Tue Apr 09, 2019 9:01 pm

I'm hoping to someone can point me to the specification or rationale for how FCP maps glyphs in a new font file. I am exporting my font with 'cmap' tables for platforms 0-2 (Unicode/Uni 2.0BMP, Mac/Roman, and Windows/UniBMP).

The first four glyphs are .notdef, .null, nonmarkingreturn, and space, as expected.

As expected:
  • .null is mapped to U+0000, which maps to x00 in the Mac/Roman and Win/UniBMP cmaps.
  • space is mapped to U+0020, which maps to x20 in the Mac/Roman and Win/UniBMP cmaps.
  • space is also mapped to U+00A0 (non-breaking space), which maps to xCA (nonBreak space) in the Mac/Roman cmap and xA0 on the Win/UniBMP cmap.
What I can't figure out are these mappings:
  1. .null to 0x08 (BS) which is **only output to the Mac/Roman cmap** (??)
  2. .null to 0x1D (GS) which is mapped in all 3 cmap tables
  3. nonmarkingreturn to 0x09 (HT) and 0x0D (CR), which are **only output to the Mac/Roman cmap** (??)
I'm not clear on the rational for these three items, and whether I should / need to carry them forward into the fonts I am creating ...

Any help / insight would be appreciated!!

-Clint

Bhikkhu Pesala
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Re: Mappings in a New FCP file

Post by Bhikkhu Pesala » Tue Apr 09, 2019 9:07 pm

Null and nonmarkingreturn glyphs are now obsolete. You could simply delete them.
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Erwin Denissen
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Re: Mappings in a New FCP file

Post by Erwin Denissen » Tue Apr 09, 2019 9:19 pm

It seems you are using a very old version of FontCreator. Why would you take so much time on these things, while recent versions of FontCreator take care of these mapping issues, so you can focus on font design?
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ClintGoss
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Re: Mappings in a New FCP file

Post by ClintGoss » Tue Apr 09, 2019 11:14 pm

I am using FCPro 11.5.0.2430 (64-bit) on Win7x64.

I realize that the FontCreator 11.5 manual Page 41 (p48 in the PDF) indicates that these are "obsolete glyphs". However, the OpenType spec 1.8.3 does call for .null at least - see the specs for the COLR table:
Fonts using COLR and CPAL tables must implement glyph ID 1 as the .null glyph.
SIL's Best Practices document at https://silnrsi.github.io/FDBP/en-US/Gl ... _0020.html currently calls for no encodings below U_0020:
We recommend that fonts not encode in the cmap characters below U+0020 SPACE.
... and this document continues with some use-case problems caused by these encodings ...

I am wondering ... is there a particular reason why FCPro takes a different approach ... and which way I should go to avoid problems down the line for the fonts I am producing ...

Erwin Denissen
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Re: Mappings in a New FCP file

Post by Erwin Denissen » Wed Apr 10, 2019 1:36 pm

We're just moving forward, and those recommendations, guidelines, and requirements are no longer in place as far as we know.

Do let us know if you've encountered specific issues related to the .null glyph. Also let us know if your fonts fail to work if the lack the .null glyph at all.
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ClintGoss
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Re: Mappings in a New FCP file

Post by ClintGoss » Wed Apr 10, 2019 2:31 pm

Thanks Erwin!

In the flock of specs, recommendations, and documentation available, it is daunting to figure out what is current and correct vs. info that is deprecated, superseded, or just plain wrong.

I'm running multiple pipelines on development and can keep a parallel line of a few fonts that carry these conditions as test cases.

Again, your feedback is appreciated!

-Clint

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