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[Variable Fonts] Check fonttools.varLib.mutator can generate a static instance from a variable font

See original GitHub issue

This test is needed because the GF Team want to generate font instances from variable fonts.

One of our variable test fonts, MarkaziText-VF.ttf (will email it to you @felipesanches ), failed in mutator with the following cli input

$./fonttools varLib.mutator MarkaziText-VF.ttf wght=500

Which produced the following traceback

Location: {'wght': 500.0}
Loading variable font
Normalized location: {'wght': 0.33331298828125}
Mutating glyf/gvar tables
Mutating GDEF/GPOS/GSUB tables
Building interpolated tables
Removing variable tables
Saving instance font MarkaziText-VF-instance.ttf
ERROR: Glyph 'uni0615' has negative advance width
ERROR: Glyph 'uniFBB4' has negative advance width
ERROR: Glyph 'uni0655' has negative advance width
Traceback (most recent call last):
  File "./fonttools", line 12, in <module>
    sys.exit(main())
  File "/usr/local/google/home/nyshadhr/src/fonttools/Lib/fontTools/__main__.py", line 29, in main
    runpy.run_module(mod, run_name='__main__')
  File "/usr/lib/python2.7/runpy.py", line 180, in run_module
    fname, loader, pkg_name)
  File "/usr/lib/python2.7/runpy.py", line 72, in _run_code
    exec code in run_globals
  File "/usr/local/google/home/nyshadhr/src/fonttools/Lib/fontTools/varLib/mutator.py", line 156, in <module>
    sys.exit(main())
  File "/usr/local/google/home/nyshadhr/src/fonttools/Lib/fontTools/varLib/mutator.py", line 150, in main
    varfont.save(outfile)
  File "/usr/local/google/home/nyshadhr/src/fonttools/Lib/fontTools/ttLib/ttFont.py", line 166, in save
    writer_reordersTables = self._save(tmp)
  File "/usr/local/google/home/nyshadhr/src/fonttools/Lib/fontTools/ttLib/ttFont.py", line 205, in _save
    self._writeTable(tag, writer, done, tableCache)
  File "/usr/local/google/home/nyshadhr/src/fonttools/Lib/fontTools/ttLib/ttFont.py", line 615, in _writeTable
    self._writeTable(masterTable, writer, done, tableCache)
  File "/usr/local/google/home/nyshadhr/src/fonttools/Lib/fontTools/ttLib/ttFont.py", line 619, in _writeTable
    tabledata = self.getTableData(tag)
  File "/usr/local/google/home/nyshadhr/src/fonttools/Lib/fontTools/ttLib/ttFont.py", line 637, in getTableData
    return self.tables[tag].compile(self)
  File "/usr/local/google/home/nyshadhr/src/fonttools/Lib/fontTools/ttLib/tables/_h_m_t_x.py", line 96, in compile
    % (self.tableTag, self.advanceName))
fontTools.ttLib.TTLibError: 'hmtx' table can't contain negative advance widths

More info in the following fonttools pr https://github.com/fonttools/fonttools/pull/1198

cc @nyshadhr9

Issue Analytics

State:
Created 6 years ago
Comments:15 (10 by maintainers)

Top GitHub Comments

1reaction

felipesanchescommented, Mar 20, 2018

That’s what people call regression testing. To make sure it never creeps up back again unnoticed 😉

1reaction

m4rc1ecommented, Mar 20, 2018

Here you go MarkaziVFs.zip

Since GF may use mutator in the future to gen instances, I’d like to dump a load of VF’s through the new fonttools and see any other unforeseen issues come up. We’re a bit too light on tests for VFs atm.

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