[feaLib] Support GPOS type 2, format 2: Class-based kerning tables
This commit is contained in:
Sascha Brawer
parent
26c02e4d95
commit
6254974112
@ -471,8 +471,8 @@ class Builder(object):
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def add_class_pair_pos(self, location, glyphclass1, value1,
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glyphclass2, value2):
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raise FeatureLibError("Class-based kerning is not yet implemented",
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location)
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lookup = self.get_lookup_(location, ClassPairPosBuilder)
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lookup.add_pair(location, glyphclass1, value1, glyphclass2, value2)
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def add_specific_pair_pos(self, location, glyph1, value1, glyph2, value2):
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lookup = self.get_lookup_(location, SpecificPairPosBuilder)
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@ -1046,6 +1046,107 @@ class SingleSubstBuilder(LookupBuilder):
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return self.buildLookup_([subtable])
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class ClassPairPosSubtableBuilder(object):
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def __init__(self, builder, valueFormat1, valueFormat2):
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self.builder_ = builder
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self.classDef1_, self.classDef2_ = None, None
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self.coverage_ = set()
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self.values_ = {} # (glyphclass1, glyphclass2) --> (value1, value2)
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self.valueFormat1_, self.valueFormat2_ = valueFormat1, valueFormat2
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self.forceSubtableBreak_ = False
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self.subtables_ = []
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def addPair(self, gc1, value1, gc2, value2):
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mergeable = (not self.forceSubtableBreak_ and
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self.classDef1_ is not None and
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self.classDef1_.canAdd(gc1) and
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self.classDef2_ is not None and
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self.classDef2_.canAdd(gc2))
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if not mergeable:
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self.flush_()
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self.classDef1_ = ClassDefBuilder(otTables.ClassDef1)
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self.classDef2_ = ClassDefBuilder(otTables.ClassDef2)
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self.coverage_ = set()
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self.values_ = {}
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self.classDef1_.add(gc1)
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self.classDef2_.add(gc2)
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self.coverage_.update(gc1)
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self.values_[(gc1, gc2)] = (value1, value2)
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def addSubtableBreak(self):
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self.forceSubtableBreak_ = True
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def subtables(self):
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self.flush_()
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return self.subtables_
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def flush_(self):
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if self.classDef1_ is None or self.classDef2_ is None:
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return
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st = otTables.PairPos()
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st.Format = 2
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st.Coverage = self.builder_.buildCoverage_(self.coverage_)
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st.ValueFormat1 = self.valueFormat1_
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st.ValueFormat2 = self.valueFormat2_
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st.ClassDef1 = self.classDef1_.build(omit_class_zero=True)
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st.ClassDef2 = self.classDef2_.build(omit_class_zero=False)
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classes1 = self.classDef1_.classes()
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classes2 = self.classDef2_.classes()
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st.Class1Count, st.Class2Count = len(classes1), len(classes2)
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st.Class1Record = []
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for c1 in classes1:
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rec1 = otTables.Class1Record()
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rec1.Class2Record = []
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st.Class1Record.append(rec1)
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for c2 in classes2:
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rec2 = otTables.Class2Record()
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val1, val2 = self.values_.get((c1, c2), (None, None))
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rec2.Value1, rec2.Value2 = val1, val2
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rec1.Class2Record.append(rec2)
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self.subtables_.append(st)
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class ClassPairPosBuilder(LookupBuilder):
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SUBTABLE_BREAK_ = "SUBTABLE_BREAK"
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def __init__(self, font, location):
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LookupBuilder.__init__(self, font, location, 'GPOS', 2)
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self.pairs = [] # [(location, gc1, value1, gc2, value2)*]
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def add_pair(self, location, glyphclass1, value1, glyphclass2, value2):
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self.pairs.append((location, glyphclass1, value1, glyphclass2, value2))
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def add_subtable_break(self, location):
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self.pairs.append((location,
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self.SUBTABLE_BREAK_, self.SUBTABLE_BREAK_,
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self.SUBTABLE_BREAK_, self.SUBTABLE_BREAK_))
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def equals(self, other):
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return (LookupBuilder.equals(self, other) and
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self.pairs == other.pairs)
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def build(self):
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builders = {}
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builder = None
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for location, glyphclass1, value1, glyphclass2, value2 in self.pairs:
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if glyphclass1 is self.SUBTABLE_BREAK_:
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if builder is not None:
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builder.addSubtableBreak()
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continue
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val1, valFormat1 = makeOpenTypeValueRecord(value1)
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val2, valFormat2 = makeOpenTypeValueRecord(value2)
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builder = builders.get((valFormat1, valFormat2))
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if builder is None:
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builder = ClassPairPosSubtableBuilder(
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self, valFormat1, valFormat2)
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builders[(valFormat1, valFormat2)] = builder
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builder.addPair(glyphclass1, val1, glyphclass2, val2)
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subtables = []
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for key in sorted(builders.keys()):
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subtables.extend(builders[key].subtables())
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return self.buildLookup_(subtables)
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class SinglePosBuilder(LookupBuilder):
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def __init__(self, font, location):
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LookupBuilder.__init__(self, font, location, 'GPOS', 1)
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@ -1126,38 +1227,47 @@ class SinglePosBuilder(LookupBuilder):
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class ClassDefBuilder(object):
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"""Helper for building ClassDef tables."""
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def __init__(self, otClass):
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self.classes = set()
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self.glyphs = {}
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self.otClass = otClass
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self.classes_ = set()
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self.glyphs_ = {}
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self.otClass_ = otClass
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def canAdd(self, glyphs):
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glyphs = frozenset(glyphs)
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if glyphs in self.classes:
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if glyphs in self.classes_:
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return True
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for glyph in glyphs:
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if glyph in self.glyphs:
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if glyph in self.glyphs_:
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return False
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return True
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def add(self, glyphs):
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glyphs = frozenset(glyphs)
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if glyphs in self.classes:
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if glyphs in self.classes_:
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return
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self.classes.add(glyphs)
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self.classes_.add(glyphs)
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for glyph in glyphs:
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assert glyph not in self.glyphs
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self.glyphs[glyph] = glyphs
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assert glyph not in self.glyphs_
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self.glyphs_[glyph] = glyphs
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def build(self):
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def classes(self):
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# In ClassDef1 tables, class id #0 does not need to be encoded
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# because zero is the default. Therefore, we use id #0 for the
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# glyph class that has the largest number of members.
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#
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# TODO: Instead of counting the number of glyphs in each class,
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# we should determine the encoded size. If the glyphs in a large
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# class form a contiguous range, the encoding is actually quite
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# compact, whereas a non-contiguous set might need a lot of
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# bytes in the output file.
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return sorted(self.classes_, key=len, reverse=True)
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def build(self, omit_class_zero):
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glyphClasses = {}
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# Class id #0 does not need to be encoded because zero is the default
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# when no class is specified. Therefore, we use id #0 for the glyph
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# class that has the largest number of members.
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classes = sorted(self.classes, key=len, reverse=True)
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for classID, glyphs in enumerate(classes):
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if classID != 0:
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for glyph in glyphs:
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glyphClasses[glyph] = classID
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classDef = self.otClass()
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for classID, glyphs in enumerate(self.classes()):
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if classID == 0 and omit_class_zero:
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continue
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for glyph in glyphs:
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glyphClasses[glyph] = classID
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classDef = self.otClass_()
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classDef.classDefs = glyphClasses
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return classDef
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@ -168,7 +168,7 @@ class BuilderTest(unittest.TestCase):
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self.expect_ttx(font, self.getpath("%s.ttx" % name))
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def test_GPOS(self):
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for name in "1 2 3 4 5 6 8".split():
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for name in "1 2 2b 3 4 5 6 8".split():
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font = makeTTFont()
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addOpenTypeFeatures(self.getpath("GPOS_%s.fea" % name), font)
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self.expect_ttx(font, self.getpath("GPOS_%s.ttx" % name))
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@ -318,16 +318,27 @@ class ClassDefBuilderTest(unittest.TestCase):
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builder.add({"a", "b"})
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builder.add({"c"})
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builder.add({"e", "f", "g", "h"})
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cdef = builder.build()
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cdef = builder.build(omit_class_zero=True)
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self.assertIsInstance(cdef, otTables.ClassDef2)
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# The largest class {"e", "f", "g", "h"} should become class ID #0.
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# Zero is the default class ID, so it does not get encoded at all.
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self.assertEqual(cdef.classDefs, {
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"a": 1,
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"b": 1,
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"c": 2
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})
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cdef = builder.build(omit_class_zero=False)
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self.assertIsInstance(cdef, otTables.ClassDef2)
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self.assertEqual(cdef.classDefs, {
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"a": 1,
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"b": 1,
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"c": 2,
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"e": 0,
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"f": 0,
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"g": 0,
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"h": 0,
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})
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def test_canAdd(self):
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b = ClassDefBuilder(otTables.ClassDef1)
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b.add({"a", "b", "c", "d"})
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9
Lib/fontTools/feaLib/testdata/GPOS_2b.fea
vendored
Normal file
9
Lib/fontTools/feaLib/testdata/GPOS_2b.fea
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@ -0,0 +1,9 @@
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@PUNC = [comma semicolon period];
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feature kern {
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pos [A] @PUNC 1;
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pos [B C] [comma] 2;
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pos [D E F] [comma] 3;
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pos [D E F] [semicolon period] 4;
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pos [G] @PUNC <5 5 5 5>;
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} kern;
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119
Lib/fontTools/feaLib/testdata/GPOS_2b.ttx
vendored
Normal file
119
Lib/fontTools/feaLib/testdata/GPOS_2b.ttx
vendored
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@ -0,0 +1,119 @@
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<?xml version="1.0" encoding="UTF-8"?>
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<ttFont>
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<GPOS>
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<Version value="1.0"/>
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<ScriptList>
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<!-- ScriptCount=1 -->
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<ScriptRecord index="0">
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<ScriptTag value="DFLT"/>
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<Script>
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<DefaultLangSys>
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<ReqFeatureIndex value="65535"/>
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<!-- FeatureCount=1 -->
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<FeatureIndex index="0" value="0"/>
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</DefaultLangSys>
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<!-- LangSysCount=0 -->
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</Script>
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</ScriptRecord>
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</ScriptList>
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<FeatureList>
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<!-- FeatureCount=1 -->
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<FeatureRecord index="0">
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<FeatureTag value="kern"/>
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<Feature>
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<!-- LookupCount=1 -->
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<LookupListIndex index="0" value="0"/>
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</Feature>
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</FeatureRecord>
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</FeatureList>
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<LookupList>
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<!-- LookupCount=1 -->
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<Lookup index="0">
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<!-- LookupType=2 -->
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<LookupFlag value="0"/>
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<!-- SubTableCount=3 -->
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<PairPos index="0" Format="2">
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<Coverage>
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<Glyph value="A"/>
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</Coverage>
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<ValueFormat1 value="4"/>
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<ValueFormat2 value="0"/>
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<ClassDef1>
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</ClassDef1>
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<ClassDef2>
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<ClassDef glyph="comma" class="0"/>
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<ClassDef glyph="period" class="0"/>
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<ClassDef glyph="semicolon" class="0"/>
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</ClassDef2>
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<!-- Class1Count=1 -->
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<!-- Class2Count=1 -->
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<Class1Record index="0">
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<Class2Record index="0">
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<Value1 XAdvance="1"/>
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</Class2Record>
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</Class1Record>
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</PairPos>
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<PairPos index="1" Format="2">
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<Coverage>
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<Glyph value="B"/>
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<Glyph value="C"/>
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<Glyph value="D"/>
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<Glyph value="E"/>
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<Glyph value="F"/>
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</Coverage>
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<ValueFormat1 value="4"/>
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<ValueFormat2 value="0"/>
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<ClassDef1>
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<ClassDef glyph="B" class="1"/>
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<ClassDef glyph="C" class="1"/>
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</ClassDef1>
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<ClassDef2>
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<ClassDef glyph="comma" class="1"/>
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<ClassDef glyph="period" class="0"/>
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<ClassDef glyph="semicolon" class="0"/>
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</ClassDef2>
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<!-- Class1Count=2 -->
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<!-- Class2Count=2 -->
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<Class1Record index="0">
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<Class2Record index="0">
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<Value1 XAdvance="4"/>
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</Class2Record>
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<Class2Record index="1">
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<Value1 XAdvance="3"/>
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</Class2Record>
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</Class1Record>
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<Class1Record index="1">
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<Class2Record index="0">
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</Class2Record>
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<Class2Record index="1">
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<Value1 XAdvance="2"/>
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</Class2Record>
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</Class1Record>
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</PairPos>
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<PairPos index="2" Format="2">
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<Coverage>
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<Glyph value="G"/>
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</Coverage>
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<ValueFormat1 value="15"/>
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<ValueFormat2 value="0"/>
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<ClassDef1>
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</ClassDef1>
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<ClassDef2>
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<ClassDef glyph="comma" class="0"/>
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<ClassDef glyph="period" class="0"/>
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<ClassDef glyph="semicolon" class="0"/>
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</ClassDef2>
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<!-- Class1Count=1 -->
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<!-- Class2Count=1 -->
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<Class1Record index="0">
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<Class2Record index="0">
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<Value1 XPlacement="5" YPlacement="5" XAdvance="5" YAdvance="5"/>
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</Class2Record>
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</Class1Record>
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</PairPos>
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</Lookup>
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</LookupList>
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</GPOS>
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</ttFont>
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