Corretto – Font Post-Processing for Glyphs

A Note About Glyphs Versions

Which Glyphs version is the best for solid results?

Most of this only applies to producing TrueType fonts with Glyphs.

My guess is that there are very few people using all the TrueType features in Glyphs (as opposed to OTF export), so when an update accidentally breaks things, the bug can go unnoticed for a while.

These are personal recommendations by me, Jens Kutílek, and your experience may be different.

Glyphs 3.1

The latest (or really only) version I can recommend to use for TrueType hinting and production is the latest version of the 3.1 series, Glyphs 3.1.2 (Build 3151).

It has a bug which causes any delta instructions that occur in glyph programs to be applied at a wrong ppem size. Corretto applies an automatic fix for this.

Glyphs 3.1 also always sets the maximum stack depth for TrueType fonts to 100, which may crash the TrueType interpreter if your font uses a large number of delta instructions. This limit can be increased by Corretto.

Glyphs 3.2

In Glyphs 3.2, the TrueType hinting output has changed under the hood. Rounding stems to full pixels, and influencing this rounding by stem deltas, doesn’t work reliably anymore.

The full pixel stems mode was most commonly used in Adobe apps, notably InDesign and Acrobat (Reader). So it affected not only designers, but many ordinary users viewing PDFs in Acrobat Reader on all platforms. TrueType fonts exported from Glyphs 3.2+ don’t use the full pixel stem mode anymore when rendered in those apps, so the lack of control over stem rounding is less of an issue.

Still, this rendering mode may be selected, for example in Windows when your gasp table disables symmetric smoothing for a ppem range.

Therefore, if there is a slight chance that your TrueType fonts will be displayed with stems rounded to full pixels, I recommend to stick to Glyphs 3.1.2.

Glyphs 3.3

Known Issues in Cutting Edge Versions

3317

Corretto can not work because Glyphs does not pass the full path of the exported fonts along when calling Corretto.