Currently unused but will be super helpful for optimizing the formats of contextual lookups.
* Splits the rules of a class contextual lookup based on explicit subtable breaks
* Returns various properties on the ruleset to help determine appropriate layout format.
* (More properties, such as "touched glyphs", planned - will be added when needed.)
* Introduce a new subclass for chained contextual (sub and pos)
* Rename .substitutions to .rules in subst builders to allow for code reuse
* Make format of subtable break marker tuple common between sub/pos
Note that prior to this patch, add_subtable_break in a Subst builder adds:
(self.SUBTABLE_BREAK_, self.SUBTABLE_BREAK_, self.SUBTABLE_BREAK_, self.SUBTABLE_BREAK_)
while add_subtable_break in a Pos builder adds:
(self.SUBTABLE_BREAK_, self.SUBTABLE_BREAK_, self.SUBTABLE_BREAK_, [self.SUBTABLE_BREAK_])
This is messy. If we read the first element from the tuple instead of the last one to test if a rule is a subtable break, we can make the marker tuple the same.
* And now the subtable break code can be hoisted into superclass
* These helper methods will make the build routine common
* Hoist common build method to superclass
The diff doesn’t show it very clearly because it’s being too clever, but all I’ve done is moved one method. Everything works apart from the error message, which comes next.
* Fix the error message
Refactors feaLib, moving code which builds OpenType lookups into otlLib. Note that this changes feaLib's concept of `location` from a tuple to an object.
Fix for #1985:
* ensure that the AxisNameID in the STAT table is not less than 256. This needed an additional argument to the addMultiLingualName() name table method.
* fvar axis name IDs must also not be less than 256, just like STAT axis names.
The following sed command can be used to update TTX sources for the LookupType
change:
$ sed -i'~' 's/<!-- LookupType=\(.\) -->/<LookupType value="\1"\/>/g' *.ttx
Before this change, feaLib would group glyph-based pair positionings
by value formats. After this change, this logic happens in otlLib.
But clients can still do their own grouping if they wish, by calling
the buildPairPosGlyphsSubtable() method directly.
Not sure if empty ComponentRecords can be optimized away.
For the time being, leaving the output unchanged so that
the refactoring has no effect on the generated files.
Although the compiler (and now XML writer) assume None if an attribute
is not set, it's extremely frustrating for other code to have to check
before accessing an attribute. So, explicitly set please!
