For the test, I used the Tests/varLib/data/Build.designspace as starting point, modified the 'a' glyph so that 1 on-curve point (the first one) becomes impliable for all the masters.
* 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
os.path.relpath requires that src and dst be on the same mount drive; GH Actions windows runner create the temporary directory on a different drive than the one where the source is cloned.
* Add designspace lib key to specify a custom feature tag for feature variations, as discussed in #2079
* Added comment for the lib key
* if the lib key is present, the 'processing' flag should be ignored completely
* Allow feature variations to be active across the entire space
* Add test with empty condition set
* Skip initial box instead of removing it
* Correct comment
Nothing clever, if the source font has a CFF2 table use it as if it were
a CFF table (i.e. non-variable, not sure what would happen in the source
CFF2 was variable already).
The SingleMaster.designspace contains only one source master, so there is no real
variation data.
Still, and empty HVAR table is added (with RegionAxisCount == fvar.AxisCount).
The gvar and cvar table are not added in this case, since they are empty and
not required.
When building a variable font, varLib.build must make sure that
the OS/2.usWeightClass is equal to the wght axis default location,
that the OS/2.usWidthClass is set to the equivalent value (1-9) of
the wdth axis default location, and finally that post.italicAngle
is set to the same default value as slnt axis.
Sometimes the base master doesn't have these values correctly
set leading to discrepancies between OS/2 and post, on the one
hand, and the fvar axes' default values.
This required a fix to fontTools/cffLib. When reading a CFF2 variable font (VF) from XML, the VF state in FontDict and PrivateDict does not get set. I made a temporary fix by adding a loop to set PrivateDict.vstore for all the PrivateDict objects after the XML file has been read. This should not be necessary, and in the near future I will revisit both this issue, and the related use of isCFF2 when compiling/decompiling.
* Added getter (in the form of a property decorator) for T2Charstring.vsindex. Fixes endless compile loop in some circumstances.
Fixed bug in mutator: need to remove vsindex from snapshotted charstrings, plus formatting clean up
* Fix for subsetting HVAR tables that have an AdvanceWidthMap when the --retain-gid option is used. Needed to make subset_test.py::test_retain_gids_cff2 tests pass.
* in varLib/cffLib.py, add support for sparse sources, and sources with more than one model, and hence more than one VarData element in the VarStore.
CFF2 source fonts with multiple FontDicts in the FDArray need some extra work. With sparse fonts, some of the source fonts may have a fewer FontDicts than the default font. The getfd_map function() builds a map from the FontDict indices in the default font to those in each region font. This is needed when building up the blend value lists in the master font FontDict PrivateDicts, in order to fetch PrivateDict values from the correct FontDict in each region font.
In specializer.py, add support for CFF2 CharStrings with blend operators. 1) In generalizeCommands, convert a blend op to a list of args that are blend lists for the following regular operator. A blend list as a default font value, followed by the delta tuple. 2) In specializeCommands(), convert these back to blend ops, combining as many successive blend lists as allowed by the stack limit.
Add test case for sparse CFF2 sources.
The test font has 55 glyphs. 2 glyphs use only 2 sources (weight = 0 and 100). The rest use 4 source fonts: the two end points of the weight axis, and two intermediate masters. The intermediate masters are only 1 design space unit apart, and are used to change glyph design at the point in design space. For the rest, at most 2 glyphs use the same set of source fonts. There are 12 source fonts.
Add test case for specializer programToCommands() and commandsToProgram by converting each CharString.program in the font to a command list, and back again, and comparing original and final versions.
* Revert "load_masters: actually assign font attributes"
This reverts commit ef1d4cd02d1e46f5dac3914f547a6e4275cf3077, which caused a
crash in `interpolate_layout()` when `deepcopy`ing OTFs.
Amend code and tests while I work on a real fix.
in a designspace document, the sources' filename attribute can now contain
a relative path to a .TTX file for that master, in addition to .TTF or .UFO
(the latter, resolved through a master_finder callable as before).
