The OpenType Layout Feature specification describes eight types of substitution lookups in the glyph substitution table (GSUB) which are all supported by FontCreator:
# |
Type |
Description |
|---|---|---|
1 |
Single |
Substitute a single glyph by another single glyph (a -> b) |
2 |
Multiple |
Substitute a single glyph by other multiple glyphs (a -> xyz) |
3 |
Alternate |
Substitute a single glyph by one of multiple alternates (a -> x or y or z) |
4 |
Ligature |
Substitute multiple glyphs by a single ligature (f f i -> ffi) |
5 |
Context |
Substitute one or more glyphs in context |
6 |
Chaining Context |
Substitute context specific glyphs (3rd -> 3rd) |
7 |
Extension Substitution |
See * below |
8 |
Reverse chaining context |
Applied in reverse order, replace single glyph in chaining context |
The OpenType Layout Feature specification describes nine types of positioning lookups in the glyph positioning table (GPOS) which are all supported by FontCreator:
# |
Type |
Description |
|---|---|---|
1 |
Single adjustment |
Change the position of a single glyph (sub/superscript) |
2 |
Pair adjustment |
Mostly used to define kerning pairs |
3 |
Cursive attachment |
Used for scripts that require glyphs to attach to the previous glyphs at exit and entry points |
4 |
Mark‑to‑Base attachment |
Attach a combining mark such as a diacritic to a base glyph |
5 |
Mark‑to‑Ligature attachment |
Attach a combining mark to a ligature |
6 |
Mark‑to‑Mark attachment |
Attach a combining mark to another mark |
7 |
Context Positioning |
Position one or more glyphs in context |
8 |
Chained Context Positioning |
Position one or more glyphs in chained context |
9 |
Extension Substitution |
See * below |
* Extension substitution is a special kind of lookup that is only used for fonts with a lot of features. FontCreator will automatically include such lookup if needed.
In addition FontCreator also supports all feature parameters currently defined.
So basically FontCreator supports all OpenType Layout Features. For an up-to-date list of things currently not fully supported, please visit our forums at https://forum.high-logic.com/viewtopic.php?f=4&t=5098
