Before this change, feaLib had assigned a lookup index at the same
time as compiling each lookup. For chains, the implicit assumption was
that the chain's targets would always come before the contexual chain.
Normally this was indeed the case, but feaLib (and also makeotf)
sometimes merge several chain targets into one single lookup,
and then this assumption was not true anymore.
In the new version, the lookups get compiled in a separate pass,
after assigning lookup indices.
https://github.com/behdad/fonttools/issues/463
No changes in the compiled binary representation, this just affects XML.
After this change, the XML for empty ValueRecords is identical to the
output from makeotf.
https://github.com/behdad/fonttools/issues/471
On Windows, some Python versions format "Jan 01" while others
format "Jan 1"; this caused test failures on the build farm.
By using a date without leading zeros (2011-12-13), we can
work around this.
https://github.com/behdad/fonttools/issues/455
Before this change, feaLib did not handle feature files that specified
`feature aalt` whose block just was referring to other features without
defining any lookups on its own. After this change, we can handle it.
Resolves https://github.com/behdad/fonttools/issues/441
The current OpenType Feature File specification is silent about
what the proper behavior should be when a single glyph has multiple
LigatureCaretByPos or LigatureCaretByIndex statements. After
this change, we match the behavior of Adobe's `makeotf` tool.
Arguably, `makeotf` might not be optimal in its current behavior,
but it seems better to match the existing toolchain than to have
two conflicting interpretations of an ambiguous spec. Once the
specification gets clarified, we will of course follow.
See https://github.com/adobe-type-tools/afdko/issues/95 for the
spec discussion.
In earlier versions of the OpenType Feature File Format specification,
the example was mal-formed so we had invented our own test case.
Adobe has kindly fixed the format specification:
https://github.com/adobe-type-tools/afdko/issues/88
This change revealed a bug in the parser where mark classes did
not get recognized as glyph classes; this is now fixed, too.
https://github.com/behdad/fonttools/issues/445
Not sure whether it makes much sense to define a contextual chain
that points to a GSUB type 3, but the OpenType feature file syntax
does not explicitly forbid it. Adobe's `makeotf` tool rejects this
kind of input with "Contextual alternate rule not yet supported";
this implies that the construct is valid (albeit definitely exotic).
Before this change, the compiler had (essentially) implemented lookup
references by inlining the statements of the invoked lookup into the
current feature block. After this change, the lookup gets compiled
separately, and any call sites make explicit calls.
Resolves https://github.com/behdad/fonttools/issues/445 for single
substitutions. The compact forms for chaining to other GSUB types
are not yet supported; these will get fixed in follow-up changes.
Before this change, the compiler would enumerate only the first
glyph class of a kerning pair. However, that behavior did not match
the behavior of the `makeotf` tool.
However, not sure how to build the otTables object graph for emitting
GPOS tables with device values; the current code thus silently strips
off any device values. Left a TODO comment for implementing this.
