def _glyphIsRtl(self, name):
"""Return whether the closest-associated unicode character is RTL."""
delims = ('.', '_')
uv = self.font[name].unicode
while uv is None and any(d in name for d in delims):
name = name[:max(name.rfind(d) for d in delims)]
if name in self.font:
uv = self.font[name].unicode
if uv is None:
return False
return unicodedata.bidirectional(unichr(uv)) in ('R', 'AL')
def _glyphIsRtl(self, name):
"""Return whether the closest-associated unicode character is RTL."""
delims = ('.', '_')
uv = self.font[name].unicode
while uv is None and any(d in name for d in delims):
name = name[:max(name.rfind(d) for d in delims)]
if name in self.font:
uv = self.font[name].unicode
if uv is None:
return False
return unicodedata.bidirectional(unichr(uv)) in ('R', 'AL')
def getPairItemDirection(self, item):
"""
Return one of: "LTR", "RTL", "MIX", False
Note that when mentioning "groups" that includes single glyphs.
A single item is treated as a group with just one member.
This was the initial description
* Associate each glyph to a Unicode character,
* Exclude from RTL kern table all glyphs associated
with Unicode characters that have Bidi_Type=L,
* Exclude from LTR kern table all glyphs associated
with Unicode characters that have Bidi_Type=R or Bidi_Type=AL.
However, the exclusion model got altered into an inclusion model
because groups could define mixed directions and thus would have
to stay in all kern tables.
An alternative way could be to break up the groups and reorder
them to create a couple of better defined groups.
FILTERING:
Only if all memnbers of a group are `False` the whole group and
subsequently pair is dissmissed. Alternativeley we could dismiss
the whole group when at least one member is `False`. But I believe
that would create more problems.
Rather: we should filter the group contents much earlier in
KernFeatureWriter.getPairs or KernFeatureWriter.getGroups
See also: the docs for options.ignoreMissingUnicodeInGroupItems
in __init__
"""
# Note: KernFeatureWriter.getPairs should already have filtered
# empty groups and nonexisting pairs, thus it is not checked here.
if item.startswith(side1FeaPrefix) or item.startswith(side2FeaPrefix):
groups = self.side1Groups if item.startswith(side1FeaPrefix) \
else self.side2Groups
names = groups[item]
else:
names = [item]
writingDirs = set()
for name in names:
unicodeChar = self.getUnicodeFromGlyphName(name)
# http://unicode.org/reports/tr9/#Table_Bidirectional_Character_Types
if unicodeChar == False:
if not self.options['ignoreMissingUnicodeInGroupItems']:
# may result in a "MIX" pair if this is a bigger group
writingDirs.add(False)
continue
bidiType = unicodedata.bidirectional(unicodeChar)
# L: Left-to-Right
if bidiType == 'L':
writingDirs.add('LTR')
# R: Right-to-Left
# AL: Right-to-Left Arabic
elif bidiType in ('R', 'AL'):
writingDirs.add('RTL')
# AN: Arabic Number
# FIXME: remove bidiType == 'AN' this from kerning? This
# filtering should rather happen earlier, somewhere in
# KernFeatureWriter.getPairs or KernFeatureWriter.getGroups
# elif bidiType == 'AN':
# writingDirs.add(False)
else:
writingDirs.add('MIX')
# if writingDirs.has(False)
# return False
if len(writingDirs) > 1:
return 'MIX'
elif len(writingDirs) == 0:
return False
return writingDirs.pop() # "LTR", "RTL", "MIX" or False
def getPairItemDirection(self, item):
"""
Return one of: "LTR", "RTL", "MIX", False
Note that when mentioning "groups" that includes single glyphs.
A single item is treated as a group with just one member.
This was the initial description
* Associate each glyph to a Unicode character,
* Exclude from RTL kern table all glyphs associated
with Unicode characters that have Bidi_Type=L,
* Exclude from LTR kern table all glyphs associated
with Unicode characters that have Bidi_Type=R or Bidi_Type=AL.
However, the exclusion model got altered into an inclusion model
because groups could define mixed directions and thus would have
to stay in all kern tables.
An alternative way could be to break up the groups and reorder
them to create a couple of better defined groups.
FILTERING:
Only if all memnbers of a group are `False` the whole group and
subsequently pair is dissmissed. Alternativeley we could dismiss
the whole group when at least one member is `False`. But I believe
that would create more problems.
Rather: we should filter the group contents much earlier in
KernFeatureWriter.getPairs or KernFeatureWriter.getGroups
See also: the docs for options.ignoreMissingUnicodeInGroupItems
in __init__
"""
# Note: KernFeatureWriter.getPairs should already have filtered
# empty groups and nonexisting pairs, thus it is not checked here.
if item.startswith(side1FeaPrefix) or item.startswith(side2FeaPrefix):
groups = self.side1Groups if item.startswith(side1FeaPrefix) \
else self.side2Groups
names = groups[item]
else:
names = [item]
writingDirs = set()
for name in names:
unicodeChar = self.getUnicodeFromGlyphName(name)
# http://unicode.org/reports/tr9/#Table_Bidirectional_Character_Types
if unicodeChar == False:
if not self.options['ignoreMissingUnicodeInGroupItems']:
# may result in a "MIX" pair if this is a bigger group
writingDirs.add(False)
continue
bidiType = unicodedata.bidirectional(unicodeChar)
# L: Left-to-Right
if bidiType == 'L':
writingDirs.add('LTR')
# R: Right-to-Left
# AL: Right-to-Left Arabic
elif bidiType in ('R', 'AL'):
writingDirs.add('RTL')
# AN: Arabic Number
# FIXME: remove bidiType == 'AN' this from kerning? This
# filtering should rather happen earlier, somewhere in
# KernFeatureWriter.getPairs or KernFeatureWriter.getGroups
# elif bidiType == 'AN':
# writingDirs.add(False)
else:
writingDirs.add('MIX')
# if writingDirs.has(False)
# return False
if len(writingDirs) > 1:
return 'MIX'
elif len(writingDirs) == 0:
return False
return writingDirs.pop() # "LTR", "RTL", "MIX" or False
