@bedhad
Address issues raised in #1403
I do think setting the dummy CFF2 PrivateDict nominalWidthX and defaultWidthX to None, which leads to the charstring.width also being None, is a good idea. I originally set them to 0, which produces a charstring width of 0, in order to avoid problems with logic that assumes that the field is good for math. However, I now think that it is better to find errors around charstring type assumptions earlier than later.
"drop_hints()" is actually not wrong - I did look at this when making the changes. For CFF2 charstrings, self.width is always equal to self.private.defaultWidthX, so the width is never inserted. This is because in psCharstrings.py::T2WidthExtractor.popallWidth(), the test "evenOdd ^ (len(args) % 2)" is alway False. Left to myself, I would not change this code. If the CFF2 charstring is correct, there is not a problem. if the CFF2 charstring is not correct, then both in drop_hints() and in T2WidthExtractor.popallWidth(), the logic will stack dump. I did add asserts, but am not totally sure it is worth the extra calls.
It is useful to re-order the CFF2 master font list to match the sorted location order, but doing so means touching internal fields of the model, so we'll move this into the VariationModel class.
Added interpolation of glyph advance width, from HVAR/hmtx, and derivation of new LSB.
Updated tests to match.
Needed to cherrypick from another branch an update for psCharstrings to allow the CFFSubr.draw() method to work.
varStore.py. Commit the correct function references.
psCharstrings.py. Add decompiler class specifically for flattening subroutinized charstrings.
mutator.py. Flatten the subroutinized charstrings, delete the Subrs.
TestCFF2VF.otf, Updated to version with subroutinization. Updated expected ttx output.
varLib.py. restore import of 'fontTools.misc.py23 import *'
varStore.py. Rename 'applyScalar' to 'interpolateFromDeltasAndScalars', and refactor common code with __git__item to a static method.
mutator.py. Update to reflect function name change to interpolateFromDeltasAndScalars. Changed some logic from one line to several lines for readability, and i to avoid flake8 warnings about line too long.
Fix syntax error reported by build system: can't mix string string types when doing literal concatenation
Fix local import reference - doesn't work in Python3.
Addressed issues raised by @msousa for PR 1345 yesterday.
Will change cff2_merge_funcs.py and cff2mergePen.py from tab to space indentations after the current comments are resolved.
Add various improvements from comments:
- do not edit the post table under varLib.build(). Setting post table format 2 or 3 is now expected to be managed by whatever calls varLib.build().
- In the t2CharStringPen module, rename closure _round() nested in makeRoundFunc to an exportable function, and use it in cff2mergePen.
- remove TypeSupply copyright from cff2mergePen.
- use modulo function to convert float to int when it is meant to be 0 in cff2mergePen.
cff2_merge_funcs.py:merge_PrivateDicts() should only be blending the hint related fields in the PrivateDict. This oversight that was surfaced by @madig reporting an error building his Cantrell font. The bug appeared when the font was subroutinized, as the pen draw method then has to interpret the Subr field in order to access T2Charstring subroutines.
Fix expected ttx output file. When I removed the logic to add glyph names to the post table, glyph names in the ttx file changed.
Miguel prefers a simple list for readability in cff2_merge_funs.py:138.
