Opening Font Files
Glyphs can open compiled font files of the following formats:
OpenType, PostScript/CFF flavor (.otf)
OpenType, TrueType flavor (.ttf)
OpenType Collection, TrueType flavor (.ttc)
Adobe Type 1, PostScript Font Binary (.pfb)
Glyphs cannot reverse-engineer all the information inside a compiled font file. Opening such a file and exporting it again will produce a font file different from the original. For example, some hinting information and OpenType tables are lost when importing a compiled font. Compiled fonts are opened in a view-only mode. Choose File → Save As… (Cmd-Shift-S) to save it to one of the source formats.
The order of the glyphs is written into a
glyphOrder custom parameter in File → Font Info… → Font.
Plug-ins can add support for opening additional font formats; see Plug-ins.
Font File Importing Behaviors
When opening a font file, Glyphs will try to apply its built-in naming scheme and sync the metrics of composite glyphs with their base glyphs. These behaviors can be disabled in the settings; see User Settings for Keep Glyph Names from Imported Files and Disable Automatic Alignment for Imported Files.
Opening TrueType Font
TrueType flavor OpenType fonts are imported, maintaining their quadratic Bézier curves. Glyphs can edit, but not create quadratic curves. Convert them to PostScript/CFF flavor cubic curves with Path → Other → Convert to Cubic. This command applies to all selected paths, layers, or glyphs. Components contained in TrueType fonts are kept.
Importing Multiple Fonts Files into a Glyphs File
Import fonts as masters by choosing File → Font Info… → Masters → → Add Other Font. See Managing Masters for details. If the newly added masters are interpolated, ensure they are compatible (see Outline Compatibility).
Importing OpenType Features
Some OpenType features cannot be reconstructed when opening a compiled OpenType file. The features in File → Font Info… → Features show a list of features that should be imported. Lookups used from multiple features are placed in a prefix named Prefix. Kerning and kerning groups are mostly preserved, but contextual kerning is not.
Importing PostScript Hints
Most glyph-level PostScript hints are preserved. Alignment zones and standard stems are also preserved. However, most glyph-level hints are not connected to nodes anymore. In a Multiple Masters setup, drag the blue circle and triangle onto outline nodes that fit the hint. See Stem Hints for details.