UFO default layer with custom name

[moyogo]

The layer name public.default indicates that the default layer has no user defined name.
glyphsLib should store the user defined default layer name and round-trip it to UFOs.

The layer lib is now stored in the master userData instead of the font userData.
When several UFOs each have a layer with the same name, their lib may be different and cannot be stored in the font userData under the same key.

This now uses master.userData["com.schriftgestaltung.Glyphs.layerLib.<layer.name>"]["com.schriftgestaltung.Glyphs.layerName"], one per layer, instead of font.userData["com.schriftgestaltung.Glyphs.layerLib.<layer.name>"]["com.schriftgestaltung.Glyphs.layerName"], one for all layers with the same name across UFOs.

[belluzj]

I was going to comment that along with updating where the UFO layer lib is stored on the Glyphs side, we should also update my diagram that explains that: https://github.com/googlefonts/glyphsLib/blob/main/tests/builder/lib_and_user_data.png

But actually my diagram seems to already be describing the new situation, so I must have implemented my own diagram wrong when I was working on this? 🙄

[madig]

Does this in any way interact with Glyphs.app layer/master names? I remember newer G2 versions letting you set the master name. Does this transport into UFo or is it a separate thing?

[moyogo]

Does this in any way interact with Glyphs.app layer/master names? I remember newer G2 versions letting you set the master name. Does this transport into UFo or is it a separate thing?

I'm not able to rename the master default layer (through the UI or the API), it just uses the name of the master.

[schriftgestalt]

Master layers are not supposed to have its own name. If a files happens to have one anyway, you can ignore it. Keeping the name around is less important in Glyphs 3 files as the important information moved to layer.attributs.