This is to be able to ignore tricky glyphs that sometimes trip up Skia PathOps.Simplify operation.
We have no idea how to fix this upstream (short of having the glyphs redrawn), and perfect is the enemy of good..
See pull request: https://github.com/fonttools/fonttools/pull/2326
The new module `otlLib.optimize.gpos` provides `compact` functions that
can reduce the file size of GPOS PairPos lookups by splitting subtables
in a smart way to avoid storing zero-valued pairs.
The compaction methods are called from `otlLib.builder` and
`varLib.merger` so that static and variable fonts can benefit from the
optimization at compile time.
The new module `otlLib.optimize` is also executable, to allow running
the optimization on existing fonts.
The optimization is a trade-off because on the one hand it can reduce
significantly the byte size of the GPOS table (up to 50% in random
Google Fonts) but on the other hand it adds to the compilation time and
may make fonts very slightly bigger once compressed to WOFF2 (because
WOFF2 doesn't mind about zero values and compresses them very well).
As such, the optimization is off by default, and you can activate it by
providing the environment variable `FONTTOOLS_GPOS_COMPACT_MODE=5` for
example (values from 0 = off to 9 = max file size savings, but many more
subtables).
The full optimizer in varLib.varStore still needs to be updated.
But this pretty much enables building 32bit VarStores, even if they
won't be fully optimal.
Part of https://github.com/fonttools/fonttools/issues/2279
I suggested Cosimo add that code in
https://github.com/fonttools/fonttools/pull/1528
Upon further inspection now, that code is unnecessary and even wrong in
cases where different masters have different ascent, because that would
result in encoding variations for vertical phantom points, which will
be then either be unused or double-apply on top of ascent etc.
* Replaced all from ...py23 import * with explicit name imports, or removed completely when possible.
* Replaced tounicode() with tostr()
* Changed all BytesIO ans StringIO imports to from io import ..., replaced all UnicodeIO with StringIO.
* Replaced all unichr() with chr()
* Misc minor tweaks and fixes
